FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003
COMPLETE
SPECIFICATION
(See Section 10; Rule 13)
CATALYSTS
ECONIC TECHNOLOGIES LTD,
a British Company of,
Level 1 Bessemer Building
Imperial College London SW7 2AZ,
Great Britain
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES
THE INVENTION AND THE MANNER IN WHICH IT IS TO BE
PERFORMED.
2
FIELD OF THE INVENTION
The present invention relates to the field of polymerisation catalysts, and
systems comprising said catalysts for polymerising carbon dioxide and an
epoxide, a lactide and/or lactone, and/or an epoxide and an anhydride.
BACKGROUND
Environmental and economic concerns associated with depleting oil resources
have triggered a growing interest in the chemical conversion of carbon dioxide
(CO2), so as to enable its use as a renewable carbon source. CO2 is, despite its
low reactivity, a highly attractive carbon feedstock, as it is inexpensive, virtually
non-toxic, abundantly available in high purity and non-hazardous. Therefore,
CO2 could be a promising substitute for substances such as carbon monoxide,
phosgene or other petrochemical feedstocks in many processes. One of the
developing applications of CO2 is the copolymerization with epoxides to yield
aliphatic polycarbonates. The development of effective catalysts to make such a
process profitable is the subject of continuous research.
In WO2009/130470, the contents of which are incorporated herein by reference
in their entirety, the copolymerisation of an epoxide with CO2 using a catalyst of
a class represented by formula (I) was described:
E1
R1
N
R4
E2
R4N
E1
R1
R4
N
NR4
E2
M M
X
X
R3 R3
R2 R2
R2 R2
(I)
WO2013/034750, the contents of which are incorporated herein by reference in
their entirety, discloses the copolymerisation of an epoxide with CO2 in the
3
presence of a chain transfer agent using a catalyst of a class represented by
formula (I):
(I)
Various compounds according to formula (I) above were tested for their ability to
catalyse the reaction between different epoxides and carbon dioxide.
In each of these tested catalysts, both occurrences of R3 were the same and all
occurrence of R4 were the same (referred to hereinafter as symmetric catalysts).
Among the epoxides employed in the copolymerization reactions of the prior art,
cyclohexene oxide (CHO) received special interest, as the product,
poly(cyclohexene carbonate) (PCHC) shows a high glass transition temperature
and reasonable tensile strength. Ethylene oxide, propylene oxide and butylene
oxide have also received interest as they produce polymers (polyalkylene
carbonates, such as PPC) with elastomeric properties which are useful in many
applications e.g. films.
The inventors have now surprisingly found that the asymmetric catalysts referred
to herein represent a novel and inventive means of catalysing the polymerisation
of carbon dioxide with various monomers to produce useful polymer products
with good activity and selectivity. .
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, there is provided a catalyst of
formula (I):
4
wherein:
M1 and M2 are independently selected from Zn(II), Cr(II), Co(II), Cu(II), Ni(II),
Mn(II), Mg(II), Fe(II), Ti(II), V(II), Cr(III)-X, Co(III)-X, Ni(III)-X, Mn(III)-X, Fe(III)-X,
Ca(II), Ge(II), Al(III)-X, Ti(III)-X, V(III)-X, Ge(IV)-(X)2 or Ti(IV)-(X)2;
R1 and R2 are independently selected from hydrogen, halide, a nitro group, a
nitrile group, an imine, an amine, an ether group, a silyl group, a silyl ether
group, a sulfoxide group, a sulfonyl group, a sulfinate group or an acetylide
group or an optionally substituted alkyl, alkenyl, alkynyl, haloalkyl, aryl,
heteroaryl, alkoxy, aryloxy, alkylthio, arylthio, alicyclic or heteroalicyclic group;
R3A and R3B are independently selected from optionally substituted alkylene,
alkenylene, alkynylene, heteroalkylene, heteroalkenylene, heteroalkynylene,
arylene, heteroarylene or cycloalkylene, wherein alkylene, alkenylene,
alkynylene, heteroalkylene, heteroalkenylene and heteroalkynylene, may
optionally be interrupted by aryl, heteroaryl, alicyclic or heteroalicyclic;
R5 is independently selected from H, or optionally substituted aliphatic,
heteroaliphatic, alicyclic, heteroalicyclic, aryl, heteroaryl, alkylheteroaryl or
alkylaryl;
E1 is C, E2 is O, S or NH or E1 is N and E2 is O;
E3, E4, E5 and E6 are each independently selected from N, NR4, O and S,
wherein when any of E3, E4, E5 or E6 are N, is , and wherein when
any of E3, E4, E5 or E6 are NR4, O or S, is ; R4 is independently
selected from H, or optionally substituted aliphatic, heteroaliphatic, alicyclic,
heteroalicyclic, aryl, heteroaryl, alkylheteroaryl or alkylaryl;
5
X is independently selected from OC(O)Rx
, OSO2R
x
, OSORx
, OSO(Rx
)2, S(O)Rx
,
ORx
, phosphinate, halide, nitrate, hydroxyl, carbonate, amino, amido or
optionally substituted aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or
heteroaryl;
Rx is independently hydrogen, or optionally substituted aliphatic, haloaliphatic,
heteroaliphatic, alicyclic, heteroalicyclic, aryl, alkylaryl or heteroaryl; and
G is absent or independently selected from a neutral or anionic donor ligand
which is a Lewis base;
and wherein:
i) R3A is different from R3B; and/or
ii) at least one occurrence of E3, E4, E5 and E6 is different to a remaining
occurrence of E3, E4, E5 and E6.
According to a second aspect of the present invention, there is provided a ligand
of formula (II):
(II)
wherein:
R1 and R2 are independently selected from hydrogen, halide, a nitro group, a
nitrile group, an imine, an amine, an ether group, a silyl group, a silyl ether
group, a sulfoxide group, a sulfonyl group, a sulfinate group or an acetylide
group or an optionally substituted alkyl, alkenyl, alkynyl, haloalkyl, aryl,
heteroaryl, alkoxy, aryloxy, alkylthio, arylthio, alicyclic or heteroalicyclic group;
6
R3A and R3B are independently selected from optionally substituted alkylene,
alkenylene, alkynylene, heteroalkylene, heteroalkenylene, heteroalkynylene,
arylene, heteroarylene or cycloalkylene, wherein alkylene, alkenylene,
alkynylene, heteroalkylene, heteroalkenylene and heteroalkynylene, may
optionally be interrupted by aryl, heteroaryl, alicyclic or heteroalicyclic;
R5 is independently selected from H, or optionally substituted aliphatic,
heteroaliphatic, alicyclic, heteroalicyclic, aryl, heteroaryl, alkylheteroaryl or
alkylaryl;
E1 is C, E2 is OY, S or NH or E1 is N and E2 is O;
Y is hydrogen or an alkali metal;
E3, E4, E5 and E6 are each independently selected from N, NR4, O and S,
wherein when any of E3, E4, E5 or E6 are N, is , and wherein when
any of E3, E4, E5 or E6 are NR4, O or S, is ; R4 is independently
selected from H, or optionally substituted aliphatic, heteroaliphatic, alicyclic,
heteroalicyclic, aryl, heteroaryl, alkylheteroaryl or alkylaryl;
and wherein:
i) R3A is different from R3B; and/or
ii) at least one occurrence of E3, E4, E5 and E6 is different to a remaining
occurrence of E3, E4, E5 and E6.
In a third aspect of the present invention, the invention extends to methods of
preparation of ligands, complexes and catalysts according to the second aspect
and first aspect respectively or as otherwise defined herein.
In a fourth aspect of the present invention, there is provided a process of
asymmetric N-substitution of a symmetrical ligand having a tetraaminophenol
coordination sphere, the process comprising the following steps:
a) protecting the amino groups of the coordination sphere of the
symmetrical ligand with an optionally substituted alkylene;
b) asymmetrically N-substituting one or more of the protected amino groups
of the product of step (a) with a substituent.
7
In a fifth aspect of the invention, there is provided a process for the reaction of (i)
carbon dioxide with an epoxide, (ii) an anhydride and an epoxide, and/or (iii) a
lactide and/or a lactone in the presence of a catalyst according to the first
aspect, optionally in the presence of a chain transfer agent.
The sixth aspect of the invention provides a product of the process of the fifth
aspect of the invention.
DEFINITIONS
For the purpose of the present invention, an aliphatic group is a hydrocarbon
moiety that may be straight chain or branched and may be completely saturated,
or contain one or more units of unsaturation, but which is not aromatic. The term
“unsaturated” means a moiety that has one or more double and/or triple bonds.
The term “aliphatic” is therefore intended to encompass alkyl, alkenyl or alkynyl
groups, and combinations thereof. An aliphatic group is preferably a C1-
20aliphatic group, that is, an aliphatic group with 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
12, 13, 14, 15, 16, 17, 18, 19 or 20 carbon atoms. Preferably, an aliphatic group
is a C1-15aliphatic, more preferably a C1-12aliphatic, more preferably a C1-
10aliphatic, even more preferably a C1-8aliphatic, such as a C1-6aliphatic group.
An alkyl group is preferably a “C1-20 alkyl group”, that is an alkyl group that is a
straight or branched chain with 1 to 20 carbons. The alkyl group therefore has 1,
2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 carbon atoms.
Preferably, an alkyl group is a C1-15alkyl, preferably a C1-12alkyl, more preferably
a C1-10alkyl, even more preferably a C1-8alkyl, even more preferably a C1-6alkyl
group. Specifically, examples of “C1-20 alkyl group“ include methyl group, ethyl
group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, sec-butyl
group, tert-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl
group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, ntridecyl
group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, nheptadecyl
group, n-octadecyl group, n-nonadecyl group, n-eicosyl group, 1,1-
dimethylpropyl group, 1,2-dimethylpropyl group, 2,2-dimethylpropyl group, 1-
ethylpropyl group, n-hexyl group, 1-ethyl-2-methylpropyl group, 1,1,2-
trimethylpropyl group, 1-ethylbutyl group, 1-methylbutyl group, 2-methylbutyl
8
group, 1,1-dimethylbutyl group, 1,2-dimethylbutyl group, 2,2-dimethylbutyl group,
1,3-dimethylbutyl group, 2,3-dimethylbutyl group, 2-ethylbutyl group, 2-
methylpentyl group, 3-methylpentyl group and the like.
Alkenyl and alkynyl groups are preferably “C2-20alkenyl” and “C2-20alkynyl”, more
preferably “C2-15alkenyl” and “C2-15alkynyl”, even more preferably “C2-12alkenyl”
and “C2-12alkynyl”, even more preferably “C2-10alkenyl” and “C2-10alkynyl”, even
more preferably “C2-8alkenyl” and “C2-8alkynyl”, most preferably “C2-6alkenyl” and
“C2-6alkynyl” groups, respectively. Alkene and alkyne should be understood
accordingly.
A heteroaliphatic group is an aliphatic group as described above, which
additionally contains one or more heteroatoms. Heteroaliphatic groups therefore
preferably contain from 2 to 21 atoms, preferably from 2 to 16 atoms, more
preferably from 2 to 13 atoms, more preferably from 2 to 11 atoms, more
preferably from 2 to 9 atoms, even more preferably from 2 to 7 atoms, wherein at
least one atom is a carbon atom. Particularly preferred heteroatoms are
selected from O, S, N, P and Si. When heteroaliphatic groups have two or more
heteroatoms, the heteroatoms may be the same or different.
An alicyclic group is a saturated or partially unsaturated cyclic aliphatic
monocyclic or polycyclic (including fused, bridging and spiro-fused) ring system
which has from 3 to 20 carbon atoms, that is an alicyclic group with 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 carbon atoms. Preferably, an
alicyclic group has from 3 to 15, more preferably from 3 to 12, even more
preferably from 3 to 10, even more preferably from 3 to 8 carbon atoms, even
more preferably from 3 to 6 carbons atoms. The term “alicyclic” encompasses
cycloalkyl, cycloalkenyl and cycloalkynyl groups. It will be appreciated that the
alicyclic group may comprise an alicyclic ring bearing one or more linking or nonlinking
alkyl substituents, such as –CH2-cyclohexyl. Specifically, examples of the
C3-20 cycloalkyl group include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,
cycloheptyl, adamantyl and cyclooctyl.
9
A heteroalicyclic group is an alicyclic group as defined above which has, in
addition to carbon atoms, one or more ring heteroatoms, which are preferably
selected from O, S, N, P and Si. Heteroalicyclic groups preferably contain from
one to four heteroatoms, which may be the same or different. Heterocyclic
groups preferably contain from 5 to 20 atoms, more preferably from 5 to 14
atoms, even more preferably from 5 to 12 atoms.
An aryl group is a monocyclic or polycyclic ring system having from 5 to 20
carbon atoms. An aryl group is preferably a “C6-12 aryl group” and is an aryl
group constituted by 6, 7, 8, 9, 10, 11 or 12 carbon atoms and includes
condensed ring groups such as monocyclic ring group, or bicyclic ring group and
the like. Specifically, examples of “C6-10 aryl group” include phenyl group,
biphenyl group, indenyl group, naphthyl group or azulenyl group and the like. It
should be noted that condensed rings such as indan and tetrahydro naphthalene
are also included in the aryl group.
A heteroaryl group is an aryl group having, in addition to carbon atoms, from one
to four ring heteroatoms which are preferably selected from O, S, N, P and Si. A
heteroaryl group preferably has from 5 to 20, more preferably from 5 to 14 ring
atoms. Specifically, examples of a heteroaryl group include pyridine, imidazole,
methylimidazole and dimethylaminopyridine.
Examples of alicyclic, heteroalicyclic, aryl and heteroaryl groups include but are
not limited to cyclohexyl, phenyl, acridine, benzimidazole, benzofuran,
benzothiophene, benzoxazole, benzothiazole, carbazole, cinnoline, dioxin,
dioxane, dioxolane, dithiane, dithiazine, dithiazole, dithiolane, furan, imidazole,
imidazoline, imidazolidine, indole, indoline, indolizine, indazole, isoindole,
isoquinoline, isoxazole, isothiazole, morpholine, napthyridine, oxazole,
oxadiazole, oxathiazole, oxathiazolidine, oxazine, oxadiazine, phenazine,
phenothiazine, phenoxazine, phthalazine, piperazine, piperidine, pteridine,
purine, pyran, pyrazine, pyrazole, pyrazoline, pyrazolidine, pyridazine, pyridine,
pyrimidine, pyrrole, pyrrolidine, pyrroline, quinoline, quinoxaline, quinazoline,
quinolizine, tetrahydrofuran, tetrazine, tetrazole, thiophene, thiadiazine,
10
thiadiazole, thiatriazole, thiazine, thiazole, thiomorpholine, thianaphthalene,
thiopyran, triazine, triazole, and trithiane.
The term “halide” or “halogen” are used interchangeably and, as used herein
mean a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the
like, preferably a fluorine atom, a bromine atom or a chlorine atom, and more
preferably a fluorine atom.
A haloalkyl group is preferably a “C1-20 haloalkyl group”, more preferably a “C1-15
haloalkyl group”, more preferably a “C1-12 haloalkyl group”, more preferably a “C1-
10 haloalkyl group”, even more preferably a “C1-8 haloalkyl group”, even more
preferably a “C1-6 haloalkyl group” and is a C1-20 alkyl, a C1-15 alkyl, a C1-12 alkyl,
a C1-10 alkyl, a C1-8 alkyl, or a C1-6 alkyl group, respectively, as described above
substituted with at least one halogen atom, preferably 1, 2 or 3 halogen atom(s).
Specifically, examples of “C1-20 haloalkyl group” include fluoromethyl group,
difluoromethyl group, trifluoromethyl group, fluoroethyl group, difluroethyl group,
trifluoroethyl group, chloromethyl group, bromomethyl group, iodomethyl group
and the like.
An alkoxy group is preferably a “C1-20 alkoxy group”, more preferably a “C1-15
alkoxy group”, more preferably a “C1-12 alkoxy group”, more preferably a “C1-10
alkoxy group”, even more preferably a “C1-8 alkoxy group”, even more preferably
a “C1-6 alkoxy group” and is an oxy group that is bonded to the previously
defined C1-20 alkyl, C1-15 alkyl, C1-12 alkyl, C1-10 alkyl, C1-8 alkyl, or C1-6 alkyl group
respectively. Specifically, examples of “C1-20 alkoxy group” include methoxy
group, ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, isobutoxy
group, sec-butoxy group, tert-butoxy group, n-pentyloxy group, isopentyloxy
group, sec-pentyloxy group, n-hexyloxy group, iso-hexyloxy group, , nhexyloxy
group, n-heptyloxy group, n-octyloxy group, n-nonyloxy group, ndecyloxy
group, n-undecyloxy group, n-dodecyloxy group, n-tridecyloxy group, ntetradecyloxy
group, n-pentadecyloxy group, n-hexadecyloxy group, nheptadecyloxy
group, n-octadecyloxy group, n-nonadecyloxy group, n-eicosyloxy
group, 1,1-dimethylpropoxy group, 1,2-dimethylpropoxy group, 2,2-
dimethylpropoxy group, 2-methylbutoxy group, 1-ethyl-2-methylpropoxy group,
11
1,1,2-trimethylpropoxy group, 1,1-dimethylbutoxy group, 1,2-dimethylbutoxy
group, 2,2-dimethylbutoxy group, 2,3-dimethylbutoxy group, 1,3-dimethylbutoxy
group, 2-ethylbutoxy group, 2-methylpentyloxy group, 3-methylpentyloxy group
and the like.
An aryloxy group is preferably a “C5-20 aryloxy group”, more preferably a “C6-12
aryloxy group”, even more preferably a “C6-10 aryloxy group” and is an oxy group
that is bonded to the previously defined C5-20 aryl, C6-12 aryl, or C6-10 aryl group
respectively.
An alkylthio group is preferably a “C1-20 alkylthio group”, more preferably a “C1-15
alkylthio group”, more preferably a “C1-12 alkylthio group”, more preferably a “C1-
10 alkylthio group”, even more preferably a “C1-8 alkylthio group”, even more
preferably a “C1-6 alkylthio group” and is a thio (-S-) group that is bonded to the
previously defined C1-20 alkyl, C1-15 alkyl, C1-12 alkyl, C1-10 alkyl, C1-8 alkyl, or C1-6
alkyl group respectively.
An arylthio group is preferably a “C5-20 arylthio group”, more preferably a “C6-12
arylthio group”, even more preferably a “C6-10 arylthio group” and is an thio (-S-)
group that is bonded to the previously defined C5-20 aryl, C6-12 aryl, or C6-10 aryl
group respectively.
An alkylaryl group is preferably a “C6-12 aryl C1-20 alkyl group”, more preferably a
preferably a “C6-12 aryl C1-16 alkyl group”, even more preferably a “C6-12 aryl C1-6
alkyl group” and is an aryl group as defined above bonded at any position to an
alkyl group as defined above. The point of attachment of the alkylaryl group to a
molecule may be via the alkyl portion and thus, preferably, the alkylaryl group is -
CH2-Ph or -CH2CH2-Ph. An alkylaryl group can also be referred to as “aralkyl”.
A silyl group is preferably a group –Si(Rs)3, wherein each Rs can be
independently an aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or
heteroaryl group as defined above. In certain embodiments, each Rs is
independently an unsubstituted aliphatic, alicyclic or aryl. Preferably, each Rs is
an alkyl group selected from methyl, ethyl or propyl.
12
A silyl ether group is preferably a group OSi(R6)3 wherein each R6 can be
independently an aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or
heteroaryl group as defined above. In certain embodiments, each R6 can be
independently an unsubstituted aliphatic, alicyclic or aryl. Preferably, each R6 is
an optionally substituted phenyl or optionally substituted alkyl group selected
from methyl, ethyl, propyl or butyl (such as n-butyl or tert-butyl (tertiary butyl )).
Exemplary silyl ether groups include OSi(Me)3, OSi(Et)3, OSi(Ph)3,
OSi(Me)2(tertiary butyl ), OSi(tertiary butyl )3 and OSi(Ph)2(tertiary butyl ).
A nitrile group (also referred to as a cyano group) is a group CN.
An imine group is a group –CRNR, preferably a group –CHNR7 wherein R7 is an
aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or heteroaryl group as
defined above. In certain embodiments, R7 is unsubstituted aliphatic, alicyclic or
aryl. Preferably R7 is an alkyl group selected from methyl, ethyl or propyl.
An acetylide group contains a triple bond -C≡C-R9, preferably wherein R9 can be
hydrogen, an aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or heteroaryl
group as defined above. For the purposes of the invention when R9 is alkyl, the
triple bond can be present at any position along the alkyl chain. In certain
embodiments, R9 is unsubstituted aliphatic, alicyclic or aryl. Preferably R9 is
methyl, ethyl, propyl or phenyl.
An amino group is preferably -NH2, -NHR10 or -N(R10)2 wherein R10 can be an
aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, a silyl group, aryl or heteroaryl
group as defined above. It will be appreciated that when the amino group is
N(R10)2, each R10 group can be the same or different. In certain embodiments,
each R10 is independently an unsubstituted aliphatic, alicyclic, silyl or aryl.
Preferably R10 is methyl, ethyl, propyl, SiMe3 or phenyl.
An amido group is preferably –NR11C(O)- or –C(O)-NR11- wherein R11 can be
hydrogen, an aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or heteroaryl
group as defined above. In certain embodiments, R11 is unsubstituted aliphatic,
13
alicyclic or aryl. Preferably R11 is hydrogen, methyl, ethyl, propyl or phenyl. The
amido group may be terminated by hydrogen, an aliphatic, heteroaliphatic,
alicyclic, heteroalicyclic, aryl or heteroaryl group.
An ester group is preferably –OC(O)R12- or –C(O)OR12- wherein R12 can be
hydrogen, an aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or heteroaryl
group as defined above. In certain embodiments, R12 is unsubstituted aliphatic,
alicyclic or aryl. Preferably R12 is hydrogen, methyl, ethyl, propyl or phenyl. The
ester group may be terminated by hydrogen, an aliphatic, heteroaliphatic,
alicyclic, heteroalicyclic, aryl or heteroaryl group.
A sulfoxide is preferably –S(O)R13 and a sulfonyl group is preferably –S(O)2R13
wherein R13 can be hydrogen, an aliphatic, heteroaliphatic, alicyclic,
heteroalicyclic, aryl or heteroaryl group as defined above. In certain
embodiments, R13 is unsubstituted aliphatic, alicyclic or aryl. Preferably R13 is
hydrogen, methyl, ethyl, propyl or phenyl.
A carboxylate group is preferably -OC(O)R14, wherein R14 can be hydrogen, an
aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or heteroaryl group as
defined above. In certain embodiments, R14 is unsubstituted aliphatic, alicyclic or
aryl. Preferably R14 is hydrogen, methyl, ethyl, propyl, butyl (for example n-butyl,
isobutyl or tert-butyl), phenyl, pentafluorophenyl, pentyl, hexyl, heptyl, octyl,
nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl,
heptadecyl, octadecyl, nonadecyl, eicosyl, trifluoromethyl or adamantyl.
In an –alkylC(O)OR19 or –alkylC(O)R19 group, R19 can be hydrogen, an aliphatic,
heteroaliphatic, alicyclic, heteroalicyclic, aryl or heteroaryl group as defined
above. In certain embodiments, R19 is unsubstituted aliphatic, alicyclic or aryl.
Preferably R19 is hydrogen, methyl, ethyl, propyl, butyl (for example n-butyl,
isobutyl or tert-butyl), phenyl, pentafluorophenyl, pentyl, hexyl, heptyl, octyl,
nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl,
heptadecyl, octadecyl, nonadecyl, eicosyl, trifluoromethyl or adamantyl.
14
An acetamide is preferably MeC(O)N(R15)2 wherein R15 can be hydrogen, an
aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or heteroaryl group as
defined above. In certain embodiments, R15 is unsubstituted aliphatic, alicyclic or
aryl. Preferably R15 is hydrogen, methyl, ethyl, propyl or phenyl.
A phosphinate group is preferably a group –OP(O)(R16)2 or –P(O)(OR16) wherein
each R16 is independently selected from hydrogen, or an aliphatic,
heteroaliphatic, alicyclic, heteroalicyclic, aryl or heteroaryl group as defined
above. In certain embodiments, R16 is aliphatic, alicyclic or aryl, which are
optionally substituted by aliphatic, alicyclic, aryl or C1-6alkoxy. Preferably R16 is
optionally substituted aryl or C1-20 alkyl, more preferably phenyl optionally
substituted by C1-6alkoxy (preferably methoxy) or unsubstituted C1-20alkyl (such
as hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, stearyl).
A sulfinate group is preferably –OSOR17 wherein R17 can be hydrogen, an
aliphatic, heteroaliphatic, haloaliphatic, alicyclic, heteroalicyclic, aryl or heteroaryl
group as defined above. In certain embodiments, R17 is unsubstituted aliphatic,
alicyclic or aryl. Preferably R17 is hydrogen, methyl, ethyl, propyl or phenyl.
A carbonate group is preferably OC(O)OR18, wherein R18 can be hydrogen, an
aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or heteroaryl group as
defined above. In certain embodiments, R18 is optionally substituted aliphatic,
alicyclic or aryl. Preferably R18 is hydrogen, methyl, ethyl, propyl, butyl (for
example n-butyl, isobutyl or tert-butyl), phenyl, pentafluorophenyl, pentyl, hexyl,
heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl,
hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, trifluoromethyl, cyclohexyl,
benzyl or adamantyl.
It will be appreciated that where any of the above groups are present in a Lewis
base G, one or more additional R groups may be present, as appropriate, to
complete the valency. For example, in the context of an amino group, an
additional R group may be present to give RNHR10., wherein R is hydrogen, an
optionally substituted aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or
15
heteroaryl group as defined above. Preferably, R is hydrogen or aliphatic,
alicyclic or aryl.
Any of the aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl, heteroaryl,
haloalkyl, alkoxy, aryloxy, alkylthio, arylthio, alkylaryl, silyl, silyl ether, ester,
sulfoxide, sulfonyl, carboxylate, carbonate, imine, acetylide, amino, phosphinate,
sulfonate or amido groups wherever mentioned in the definitions above, may
optionally be substituted by halogen, hydroxy, nitro, carboxylate, carbonate,
alkoxy, aryloxy, alkylthio, arylthio, heteroaryloxy, alkylaryl, amino, amido, imine,
nitrile, silyl, silyl ether, ester, sulfoxide, sulfonyl, acetylide, phosphinate, sulfonate
or optionally substituted aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or
heteroaryl groups (for example, optionally substituted by halogen, hydroxy, nitro,
carbonate, alkoxy, aryloxy, alkylthio, arylthio, amino, imine, nitrile, silyl, sulfoxide,
sulfonyl, phosphinate, sulfonate or acetylide).
It will be appreciated that although in formula (I), the groups X and G are
illustrated as being associated with a single M1 or M2 metal centre, one or more
X and G groups may form a bridge between the M1 and M2 metal centres.
For the purposes of the present invention, the epoxide substrate is not limited.
The term epoxide therefore relates to any compound comprising an epoxide
moiety. Examples of epoxides which may be used in the present invention
include, but are not limited to, cyclohexene oxide, styrene oxide, propylene
oxide, butylene oxide, substituted cyclohexene oxides (such as limonene oxide,
C10H16O or 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, C11H22O), alkylene
oxides (such as ethylene oxide and substituted ethylene oxides) or substituted or
unsubstituted oxiranes (such as oxirane, epichlorohydrin, 2-(2-
methoxyethoxy)methyl oxirane (MEMO), 2-(2-(2-methoxyethoxy)ethoxy)methyl
oxirane (ME2MO), 2-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)methyl oxirane
(ME3MO), 1,2-epoxybutane, glycidyl ethers), vinyl-cyclohexene oxide, 3-phenyl-
1,2-epoxypropane, 1,2- and 2,3-epoxybutane, isobutylene oxide, cyclopentene
oxide, 2,3-epoxy-1,2,3,4-tetrahydronaphthalene, indene oxide, and
functionalized 3,5-dioxaepoxides. Examples of functionalized 3,5-dioxaepoxides
include:
16
.
The epoxide moiety may be a glycidyl ether, glycidyl ester or glycidyl carbonate.
Examples of glycidyl ethers, glycidyl esters and glycidyl carbonates include:
.
The epoxide substrate may contain more than one epoxide moiety, i.e. it may be
a bis-epoxide, a tris-epoxide, or a multi-epoxide containing moiety. Examples of
17
compounds including more than one epoxide moiety include bisphenol A
diglycidyl ether and 3,4-epoxycyclohexylmethyl 3,4-
epoxycyclohexanecarboxylate. It will be understood that reactions carried out in
the presence of one or more compounds having more than one epoxide moiety
may lead to cross-linking in the resulting polymer.
The skilled person will appreciate that the epoxide can be obtained from “green”
or renewable resources. The epoxide may be obtained from a (poly)unsaturated
compound, such as those deriving from a fatty acid and/or terpene, obtained
using standard oxidation chemistries.
The epoxide moiety may contain –OH moieties, or protected –OH moieties. The
–OH moieties may be protected by any suitable protecting group. Suitable
protecting groups include methyl or other alkyl groups, benzyl, allyl, tert-butyl,
tetrahydropyranyl (THP), methoxymethyl (MOM), acetyl (C(O)alkyl), benzolyl
(C(O)Ph), dimethoxytrityl (DMT), methoxyethoxymethyl (MEM), p-methoxybenzyl
(PMB), trityl, silyl (such as trimethylsilyl (TMS), t-Butyldimethylsilyl (TBDMS), tButyldiphenylsilyl
(TBDPS), tri-iso-propylsilyloxymethyl (TOM), and
triisopropylsilyl (TIPS)), (4-methoxyphenyl)diphenylmethyl (MMT),
tetrahydrofuranyl (THF), and tetrahydropyranyl (THP).
The epoxide preferably has a purity of at least 98%, more preferably >99%.
It will be understood that the term “an epoxide” is intended to encompass one or
more epoxides. In other words, the term “an epoxide” refers to a single epoxide,
or a mixture of two or more different epoxides. For example, the epoxide
substrate may be a mixture of ethylene oxide and propylene oxide, a mixture of
cyclohexene oxide and propylene oxide, a mixture of ethylene oxide and
cyclohexene oxide, or a mixture of ethylene oxide, propylene oxide and
cyclohexene oxide.
The skilled person will also understand that substituted and unsubstituted
oxetanes can be used in place of, and in addition to, the epoxides of the second
aspect of the invention. Suitable oxetanes include unsubstituted or substituted
18
oxetanes (preferably substituted at the 3-position by halogen, alkyl
(unsubstituted or substituted by –OH or halogen), amino, hydroxyl, aryl (e.g.
phenyl), alkylaryl (e.g. benzyl)). Exemplary oxetanes include oxetane, 3-ethyl-3-
oxetanemethanol, oxetane-3-methanol, 3-methyl-3-oxetanemethanol, 3-
methyloxetane, 3-ethyloxetane, etc.
The term anhydride relates to any compound comprising an anhydride moiety in
a ring system (i.e. a cyclic anhydride). Preferably, the anhydrides which are
useful in the present invention have the following formula:
Wherein m’’ is 1, 2, 3, 4, 5, or 6 (preferably 1 or 2), each Ra1, Ra2, Ra3 and Ra4 is
independently selected from hydrogen, halogen, hydroxyl, nitro, alkoxy, aryloxy,
heteroaryloxy, amino, alkylamino, imine, nitrile, acetylide, carboxylate or
optionally substituted aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl,
heteroaryl, alkylaryl or alkylheteroaryl; or two or more of Ra1, Ra2, Ra3 and Ra4
can be taken together to form a saturated, partially saturated or unsaturated 3 to
12 membered, optionally substituted ring system, optionally containing one or
more heteroatoms, or can be taken together to form a double bond. Each Q is
independently C, O, N or S, preferably C, wherein Ra3 and Ra4 are either present,
or absent, and can either be or , according to the valency of
Q. It will be appreciated that when Q is C, and is , Ra3 and Ra4 (or
two Ra4 on adjacent carbon atoms) are absent. The skilled person will appreciate
that the anhydrides may be obtained from “green” or renewable resources.
Preferable anhydrides are set out below.
19
, , , , ,
, , , , ,
, , , , .
The term lactone relates to any cyclic compound comprising a–C(O)O- moiety in
the ring. Preferably, the lactones which are useful in the present invention have
the following formula:
Wherein m is 1 to 20 (e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
18, 19 or 20), preferably 2, 4, or 5; and RL1 and RL2 are independently selected
from hydrogen, halogen, hydroxyl, nitro, alkoxy, aryloxy, heteroaryloxy, amino,
alkylamino, imine, nitrile, acetylide, carboxylate or optionally substituted aliphatic,
heteroaliphatic, alicyclic, heteroalicyclic, aryl, heteroaryl, alkylaryl or
alkylheteroaryl. Two or more of RL1 and RL2 can be taken together to form a
saturated, partially saturated or unsaturated 3 to 12 membered, optionally
substituted ring system, optionally containing one or more heteroatoms. When m
is 2 or more, the RL1 and RL2 on each carbon atom may be the same or different.
Preferably RL1 and RL2 are selected from hydrogen or alkyl. Preferably, the
lactone has the following structure:
, , . , , .
20
The term lactide is a cyclic compound containing two ester groups. Preferably,
the lactides which are useful in the present invention have the following formula:
Wherein m’ is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, (preferably 1 or 2, more preferably, 1)
and RL3 and RL4 are independently selected from hydrogen, halogen, hydroxyl,
nitro, alkoxy, aryloxy, heteroaryloxy, amino, alkylamino, imine, nitrile, acetylide,
carboxylate or optionally substituted aliphatic, heteroaliphatic, alicyclic,
heteroalicyclic, aryl, heteroaryl, alkylaryl or alkylheteroaryl. Two or more of RL3
and RL4 can be taken together to form a saturated, partially saturated or
unsaturated 3 to 12 membered, optionally substituted ring system, optionally
containing one or more heteroatoms, When m’ is 2 or more, the RL3 and RL4 on
each carbon atom may be the same or different or one or more RL3 and RL4 on
adjacent carbon atoms can be absent, thereby forming a double or triple bond. It
will be appreciated that while the compound has two moieties represented by (-
CRL3R
L4)m’, both moieties will be identical. Preferably, m’ is 1, RL4 is H, and RL3 is
H, hydroxyl or a C1-6alkyl, preferably methyl. The stereochemistry of the moiety
represented by (-CRL3R
L4)m’ can either be the same (for example RR-lactide or
SS-lactide), or different (for example, meso-lactide). The lactide may be a
racemic mixture, or may be an optically pure isomer. Preferably, the lactide has
the following formula:
, or .
The term “lactone and/or lactide” used herein encompasses a lactone, a lactide
and a combination of a lactone and a lactide. Preferably, the term “lactone
and/or lactide” means a lactone or a lactide.
21
Preferred optional substituents of the groups Ra1
, R
a2, Ra3, Ra4, RL1, RL2, RL3 and
R
L4 include halogen, nitro, hydroxyl, unsubstituted aliphatic, unsubstituted
heteroaliphatic unsubstituted aryl, unsubstituted heteroaryl, alkoxy, aryloxy,
heteroaryloxy, amino, alkylamino, imine, nitrile, acetylide, and carboxylate.
DETAILED DESCRIPTION
In the first aspect of the invention, there is provided a catalyst of formula (I):
(I)
wherein:
M1 and M2 are independently selected from Zn(II), Cr(II), Co(II), Cu(II), Mn(II),
Mg(II), Ni(II), Fe(II), Ti(II), V(II), Cr(III)-X, Co(III)-X, Ni(III)-X, Mn(III)-X, Fe(III)-X,
Ca(II), Ge(II), Al(III)-X, Ti(III)-X, V(III)-X, Ge(IV)-(X)2 or Ti(IV)-(X)2;
R1 and R2 are independently selected from hydrogen, halide, a nitro group, a
nitrile group, an imine, an amine, an ether group, a silyl group, a silyl ether
group, a sulfoxide group, a sulfonyl group, a sulfinate group or an acetylide
group or an optionally substituted alkyl, alkenyl, alkynyl, haloalkyl, aryl,
heteroaryl, alkoxy, aryloxy, alkylthio, arylthio, alicyclic or heteroalicyclic group;
R3A and R3B are independently selected from optionally substituted alkylene,
alkenylene, alkynylene, heteroalkylene, heteroalkenylene, heteroalkynylene,
arylene, heteroarylene or cycloalkylene, wherein alkylene, alkenylene,
alkynylene, heteroalkylene, heteroalkenylene and heteroalkynylene, may
optionally be interrupted by aryl, heteroaryl, alicyclic or heteroalicyclic;
22
R5 is independently selected from H, or optionally substituted aliphatic,
heteroaliphatic, alicyclic, heteroalicyclic, aryl, heteroaryl, alkylheteroaryl or
alkylaryl;
E1 is C, E2 is O, S or NH or E1 is N and E2 is O;
E3, E4, E5 and E6 are each independently selected from N, NR4, O and S,
wherein when any of E3, E4, E5 or E6 are N, is , and wherein when
any of E3, E4, E5 or E6 are NR4, O or S, is ; R4 is independently
selected from H, or optionally substituted aliphatic, heteroaliphatic, alicyclic,
heteroalicyclic, aryl, heteroaryl, alkylheteroaryl or alkylaryl;
X is independently selected from OC(O)Rx
, OSO2R
x
, OSORx
, OSO(Rx
)2, S(O)Rx
,
ORx
, phosphinate, halide, nitrate, hydroxyl, carbonate, amino, amido or
optionally substituted aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or
heteroaryl;
Rx is independently hydrogen, or optionally substituted aliphatic, haloaliphatic,
heteroaliphatic, alicyclic, heteroalicyclic, aryl, alkylaryl or heteroaryl; and
G is absent or independently selected from a neutral or anionic donor ligand
which is a Lewis base;
and wherein:
i) R3A is different from R3B; and/or
ii) at least one occurrence of E3, E4, E5 and E6 is different to a remaining
occurrence of E3, E4, E5 and E6.
Preferably, each of the occurrences of the groups R1 and R2 may be the same or
different. Preferably R1 and R2 are independently selected from hydrogen,
halide, amino, nitro, sulfoxide, sulfonyl, sulfinate, silyl, silyl ether and an
optionally substituted alkyl, alkenyl, aryl, heteroaryl, alkoxy, aryloxy or alkylthio.
Preferably each occurrence of R2 is the same. Preferably, each occurrence of R2
is the same, and is hydrogen.
Even more preferably, R2 is hydrogen and R1 is independently selected from
hydrogen, halide, amino, nitro, sulfoxide, sulfonyl, sulfinate, silyl ether and
optionally substituted alkyl, alkenyl, aryl, heteroaryl, alkoxy, aryloxy, alkylthio,
arylthio, such as hydrogen, C1-6alkyl (e.g. haloalkyl), alkoxy, aryl, halide, nitro,
23
sulfonyl, silyl and alkylthio, for example, tertiary butyl, isopropyl, methyl,
methyloxy, hydrogen, nitro, dimethylsulfoxide, trialkylsilyl for example triethylsilyl,
silyl ether, halogen or phenyl. Most preferably R1 is tertiary butyl and R2 is
hydrogen.
Each occurrence of R1 can be the same or different, and R1 and R2 can be the
same or different. Preferably each occurrence of R1 is the same. Preferably,
each occurrence of R1
is the same, and each occurrence of R2 is the same, and
R1 is different to R2. The skilled person will appreciate that when each
occurrence of R1 is different, this adds to the asymmetry of the catalyst.
It will be appreciated that the groups R3A and R3B can be a disubstituted alkyl,
alkenyl, alkynyl, heteroalkyl, heteroalkenyl or heteroalkynyl group which may
optionally be interrupted by an aryl, heteroaryl, alicyclic or heteroalicyclic group,
or may be a disubstituted aryl or cycloalkyl group which acts as a bridging group
between two nitrogen centres in the catalyst of formula (I). Thus, where R3A or
R3B is an alkylene group, such as dimethylpropylene, the R3A or R3B group has
the structure –CH2-C(CH3)2-CH2-. The definitions of the alkyl, aryl, cycloalkyl etc
groups set out above therefore also relate respectively to the alkylene, arylene,
cycloalkylene etc groups set out for R3A or R3B, and may be optionally
substituted. Exemplary options for R3A and R3B include ethylene, 2,2-
dimethylpropylene, 2,2-fluoropropylene, propylene, butylene, phenylene,
cyclohexylene or biphenylene, more preferably 2,2-dimethylpropylene, 2,2-
fluoropropylene, propylene, cyclohexylene or phenylene. When R3A or R3B is
cyclohexylene, it can be the racemic, RR- or SS- forms. Preferably R3A or R3B
are selected from ethylene, propylene, a substituted propylene, such as 2,2-
di(alkyl)propylene, phenylene, or cyclohexylene, more preferably R3A or R3B are
2,2-di(methyl)propylene.
When each occurrence of E3, E4, E5 and E6 is the same, R3A is different to R3B. It
will also be appreciated that when at least one occurrence of E3, E4, E5 and E6 is
different to a remaining occurrence of E3, E4, E5 and E6, R3A can be the same as,
or different to R3B.
24
Preferably, when R3A is different to R3B, R3A can be optionally substituted
alkylene (for example, optionally substituted propylene, e.g. 2,2-
dimethylpropylene, 2,2-fluoropropylene or propylene), or optionally substituted
cycloalkylene (such as cyclohexylene), and R3B can be optionally substituted
arylene (such as phenylene or biphenylene), or optionally substituted alkylene
(for example, optionally substituted propylene, e.g. 2,2-dimethylpropylene, 2,2-
fluoropropylene, ethylene or propylene).
In a first preferred embodiment, R3A is 2,2-dimethylpropylene, and R3B is
phenylene.
In a second preferred embodiment, R3A is a disubstituted cycloalkylene which
acts as a bridging group between two nitrogen centres in the catalyst of formula
(I), and R3B is 2,2-dimethylpropylene.
In a third preferred embodiment, R3A is 2,2-dimethylpropylene, and R3B is
propylene or ethylene.
In a fourth preferred embodiment, R3A is propylene, and R3B is 2,2-
dimethylpropylene.
E3, E4, E5 and E6 are each independently selected from N, NR4, O or S. The
skilled person will understand that when any of E3, E4, E5 or E6 are N, is
. It will also be understood that when any of E3, E4, E5 or E6 are NR4, O or
S, is .
When R3A and R3B are the same, at least one occurrence of E3, E4, E5 or E6 is
different to a remaining occurrence of E3, E4, E5 and E6.
Preferably when at least one occurrence of E3, E4, E5 or E6 is different to a
remaining occurrence of E3, E4, E5 and E6, each E3, E4, E5 and E6 is NR4, but at
least one of the R4 groups is different from a remaining R4 groups.
Alternatively, when at least one occurrence of E3, E4, E5 or E6 is different to a
remaining occurrence of E3, E4, E5 and E6, and at least one occurrence of E3, E4,
25
E5 or E6 is NR4, at least one of the remaining E3, E4, E5 and E6 groups is selected
from N, O or S.
It will be understood that when R3A is different to R3B, each E3, E4, E5 and E6 may
be the same or different.
Preferably, when R3A is different to R3B, each E3, E4, E5 and E6 are the same.
When each of E3, E4, E5 and E6 are the same, preferably each of E3, E4, E5 and
E6 are NR4, more preferably each of E3, E4, E5 and E6 are NH.
It will be understood that E3 and E5 may be the same, E3 and E4 may be the
same, E4 and E6 may be the same, E4 and E5 may be the same, E5 and E6 may
be the same, and/or E3 and E6 may be the same.. It is preferred that E3 and E5
are the same, and E4 and E6 are the same, and E3 and E5 are different to E4 and
E6, preferably E3 and E5 are S or O and E4 and E6 are N or NR4 (such as NH).
Alternatively, E3 and E4 can be the same, and E5 and E6 can be the same, and
E3 and E4 are different to E5 and E6, preferably E3 and E4 are S and E5 and E6
are N or NR4 (such as NH).
Preferably each R4 is independently selected from hydrogen, and an optionally
substituted alkyl, alkenyl, alkynyl, aryl, heteroalkyl, heteroalkenyl, heteroalkynyl
or heteroaryl. Preferably, at least one R4 is hydrogen. At least one R4 is may be
different to a remaining R4 group/s. When each R4 is the same, it is preferably
selected from hydrogen, and an optionally substituted alkyl, alkenyl, alkynyl, aryl,
heteroalkyl, heteroalkenyl, heteroalkynyl or heteroaryl. Exemplary options for R4
include hydrogen, methyl, ethyl, n-propyl, n-butyl, isopropyl, tertiary butyl, benzyl,
phenyl, –alkyl-C(O)-OR19 (as defined hereinabove for example methyl
propanoate), alkyl nitrile of the formula –alkyl-C≡N or alkyl ketone/aldehyde of
the formula alkyl-C(O)-R19. A further exemplary option is methylpyridine.
Preferably each E3, E4, E5 and E6 is NR4, and one of the R4 groups is different,
preferably E4 is different. More preferably one of the R4 groups is selected from
an optionally substituted alkyl or heteroalkyl. Still more preferably one of the R4
groups is selected from methyl, ethyl, propyl, butyl or–alkyl- C(O)-OR19 as
26
defined hereinabove, for example methyl propanoate. Preferably the remaining
R4 groups are hydrogen.
Preferably each E3, E4, E5 and E6 is NR4, and two of the R4 groups are different,
preferably E3 and E5 are different or E4 and E5 are different. More preferably two
of the R4 groups are selected from an optionally substituted alkyl or heteroalkyl.
Still more preferably two of the R4 groups are selected from methyl, ethyl, propyl,
butyl or –alkyl-C(O)-OR19 as defined hereinabove, for example methyl
propanoate . Preferably the remaining R4 groups are hydrogen.
Preferably two of E3, E4, E5 and E6 are NR4, and two of E3, E4, E5 and E6 are N.
More preferably two of E3, E4, E5 and E6 are NH and two of E3, E4, E5 and E6 are
N. Still more preferably, E4 and E6 are NH and E3 and E5 are N, or E3 and E5 are
NH and E4 and E6 are N.
Preferably two of E3, E4, E5 and E6 are S, and two of E3, E4, E5 and E6 are NR4.
More preferably two of E3, E4, E5 and E6 are S, and two of E3, E4, E5 and E6 are
NH. Still more preferably E3 and E5 are S, and , E4 and E6 are NH.
Preferably each R5 is independently selected from hydrogen, and optionally
substituted aliphatic or aryl. More preferably, each R5 is independently selected
from hydrogen, and optionally substituted alkyl or aryl. Even more preferably,
each R5 is the same, and is selected from hydrogen, and optionally substituted
alkyl or aryl. Exemplary R5 groups include hydrogen, methyl, ethyl, phenyl and
trifluoromethyl, preferably hydrogen, methyl or trifluoromethyl. Even more
preferably, each R5 is hydrogen.
Preferably both occurrences of E1 are C and both occurrences of E2 are the
same, and selected from O, S or NH. Even more preferably, both occurrences of
E1 are C and both occurrences of E2 are O.
Each X is independently selected from OC(O)Rx
, OSO2R
x
, OS(O)Rx
, OSO(Rx
)2,
S(O)Rx
, ORx
, phosphinate, halide, nitro, hydroxyl, carbonate, amino, amido and
optionally substituted aliphatic, heteroaliphatic (for example silyl), alicyclic,
27
heteroalicyclic, aryl or heteroaryl. Preferably each X is independently OC(O)Rx
,
OSO2R
x
, OS(O)Rx
, OSO(Rx
)2, S(O)Rx
, ORx
, halide, nitrate, hydroxyl, carbonate,
amino, nitro, amido, alkyl (e.g. branched alkyl), heteroalkyl, (for example silyl),
aryl or heteroaryl. In particularly preferred embodiments, each X is
independently OC(O)Rx
, ORx
, halide, carbonate, amino, nitro, alkyl, aryl,
heteroaryl, phosphinate or OSO2R
x
. Preferred optional substituents for when X is
aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or heteroaryl include
halogen, hydroxyl, nitro, cyano, amino, or substituted or unsubstituted aliphatic,
heteroaliphatic, alicyclic, heteroalicyclic, aryl or heteroaryl. Each X may be the
same or different and preferably each X is the same.
R
x
is independently hydrogen, or optionally substituted aliphatic, haloaliphatic,
heteroaliphatic, alicyclic, heteroalicyclic, aryl, alkylaryl or heteroaryl. Preferably,
R
x
is alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl or alkylaryl. Preferred
optional substitutents for Rx
include halogen, hydroxyl, cyano, nitro, amino,
alkoxy, alkylthio, or substituted or unsubstituted aliphatic, heteroaliphatic,
alicyclic, heteroalicyclic, aryl or heteroaryl (e.g. optionally substituted alkyl, aryl,
or heteroaryl).
Exemplary options for X include acetate, trifluoroacetyl, octanoate, carbonate, 2-
ethylhexanoate, cyclohexylbutyrate, dimethyl sulfonyl, ethyl, methyl, methyloxy,
isopropyloxy, tertiary butyloxy, halogen (such as chloride, bromide, iodide,
flouride), diisopropylamide or bis(trimethylsilyl)amide, phenoxy, n-butyloxy,
salicylate, dioctyl phosphinate, diphenyl phosphinate etc. Preferably X is acetate.
M1 and M2 are independently selected from Zn(II), Cr(III), Cr(II), Co(III), Co(II),
Cu(II), Ni(II), Ni(III), Mn(III), Mn(II), Mg(II), Fe(II), Fe(III), Ca(II), Ge(II), Ti(II),
Al(III), Ti(III), V(II), V(III), Ge(IV) or Ti(IV). Preferably, M1 and M2 are
independently selected from Zn(II), Cr(III), Co(II), Mn(II), Mg(II), Ni(II), Ni(III),
Fe(II) and Fe(III), even more preferably, M1 and M2 are independently selected
from Zn(II), Cr(III), Co(II), Mn(II), Ni(II), Ni(III), Mg(II), Fe(II), and Fe(III), and even
more preferably, M1 and M2 are independently selected from Zn(II), Ni(II), Ni(III)
and Mg(II). Still more preferably M1 and M2 are independently selected from
28
Ni(II), Ni(III), or Mg(II) .Preferably M1 and M2 are the same. Most preferably M1
and M2 are the same and are Ni(II) or Mg(II).
It will be appreciated that when M1 or M2 is Cr(III), Co(III), Mn(III), Ni(III) or Fe(III),
the catalyst of formula (I) will contain an additional X group co-ordinated to the
metal centre, wherein X is as defined above. It will also be appreciated that
when M1 or M2is Ge(IV) or Ti(IV), the catalyst of formula (III) will contain two
additional X group co-ordinated to the metal centre, wherein X is as defined
above. It will be understood that when M1 or M2 is Ge(IV) or Ti(IV), both G may
be absent.
When G is not absent, it is a group which is capable of donating a lone pair of
electrons (i.e. a Lewis base). G can be a nitrogen-containing Lewis base. Each
G may be neutral or negatively charged. If G is negatively charged, then one or
more positive counterions will be required to balance out the charge of the
complex. Suitable positive counterions include group 1 metal ions (Na+
, K+
, etc),
group 2 metal ions (Mg2+, Ca2+, etc), imidazolium ions, a positively charged
optionally substituted heteroaryl, heteroaliphatic or heteroalicyclic group,
ammonium ions (i.e. N(R12)4
+
), iminium ions (i.e. (R12)2C=N(R12)2
+
, such as
bis(triphenylphosphine)iminium ions) or phosphonium ions (P(R12)4
+
), wherein
each R12 is independently selected from hydrogen or optionally substituted
aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or heteroaryl. Exemplary
counterions include [H-B]+ wherein B is selected from triethylamine, 1,8-
diazabicyclo[5.4.0]undec-7-ene and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-
ene.
G is preferably independently selected from an optionally substituted
heteroaliphatic group, an optionally substituted heteroalicyclic group, an
optionally substituted heteroaryl group, a halide, hydroxide, hydride, a
carboxylate and water. More preferably, G is independently selected from water,
an alcohol (e.g methanol), a substituted or unsubstituted heteroaryl (imidazole,
methyl imidazole (for example, N-methyl imidazole), pyridine, 4-
dimethylaminopyridine, pyrrole, pyrazole, etc), an ether (dimethyl ether,
diethylether, cyclic ethers, etc), a thioether, carbene, a phosphine, a phosphine
29
oxide, a substituted or unsubstituted heteroalicyclic (morpholine, piperidine,
tetrahydrofuran, tetrahydrothiophene, etc), an amine, an alkyl amine
trimethylamine, triethylamine, etc), acetonitrile, an ester (ethyl acetate, etc), an
acetamide (dimethylacetamide, etc), a sulfoxide (dimethylsulfoxide, etc), a
carboxylate, a hydroxide, hydride, a halide, a nitrate, a sulfonate, etc. It will be
appreciated that one or both instances of G can be independently selected from
optionally substituted heteroaryl, optionally substituted heteroaliphatic, optionally
substituted heteroalicyclic, halide, hydroxide, hydride, an ether, a thioether,
carbene, a phosphine, a phosphine oxide, an amine, an alkyl amine, acetonitrile,
an ester, an acetamide, a sulfoxide, a carboxylate, a nitrate or a sulfonate. G
may be a halide; hydroxide; hydride; water; a heteroaryl, heteroalicyclic or
carboxylate group which are optionally substituted by alkyl, alkenyl, alkynyl,
alkoxy, halogen, hydroxyl, nitro or nitrile. Preferably, G is independently
selected from halide; water; a heteroaryl optionally substituted by alkyl (e.g.
methyl, ethyl etc), alkenyl, alkynyl, alkoxy (preferably methoxy), halogen,
hydroxyl, nitro or nitrile. It will be understood that one or both instances of G may
be negatively charged (for example, halide). Preferably, one or both instances
of G is an optionally substituted heteroaryl. Exemplary G groups include
chloride, bromide, pyridine, methylimidazole (for example N-methyl imidazole)
and dimethylaminopyridine (for example, 4-methylaminopyridine).
It will be appreciated that when a G group is present, the G group may be
associated with a single M metal centre as shown in formula (I), or the G group
may be associated with both metal centres and form a bridge between the two
metal centres, as shown below in formula (Ia):
30
(Ia)
Wherein R1, R2, R3A, R3B, R4, E1, E2, E3, E4, E5, E6, R5, M, G and X, are as
defined for formula (I). It will also be appreciated that X may form a bridge
between the two metal centres.
The skilled person will understand that, in the solid state, the catalysts of the first
aspect may be associated with solvent molecules such as water, or alcohol (e.g.
methanol or ethanol). It will be appreciated that the solvent molecules may be
present in a ratio of less than 1:1 relative to the molecules of catalyst of the first
aspect (i.e. 0.2:1, 0.25:1, 0.5:1), in a ratio of 1:1, relative to the molecules of
catalyst of the first aspect, or in a ratio of greater than 1:1, relative to the
molecules of catalyst of the first aspect.
The skilled person will understand that, in the solid state, the catalysts of the first
aspect may form aggregates. For example, the catalyst of the first aspect may
be a dimer, a trimer, a tetramer, a pentamer, or higher aggregate.
It will be appreciated that the preferred features described above for the catalyst
of the first aspect may be present in combination mutatis mutandis.
For example, each occurrence of R2 and R5 are H, E1 is C and E2 is O, S or NH
(preferably E2 is O).
31
Preferably, both occurrences of R1 are the same, and are selected from
hydrogen, halide, amino, nitro, sulfoxide, sulfonyl, sulfinate, silyl, silyl ether and
an optionally substituted alkyl, alkenyl, aryl, heteroaryl, alkoxy, aryloxy or
alkylthio; R2 is hydrogen; R3A and R3B are the same or different, and are selected
from substituted or unsubstituted alkylene, substituted or unsubstituted
cycloalkylene and substituted or unsubstituted arylene; E3 to E6 are the same or
different and are selected from NR4, S, N or O; R4 is hydrogen, an optionally
substituted alkyl or heteroalkyl; each X is the same, and is selected from
OC(O)Rx
, ORx
, halide, carbonate, amino, nitro, alkyl, aryl, heteroaryl,
phosphinate or OSO2R
x
, Rx
is alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl
or alkylaryl; Rx
is alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl or alkylaryl;
each G (where present) is independently selected from halide; water; a
heteroaryl optionally substituted by alkyl, alkenyl, alkynyl, alkoxy, halogen,
hydroxyl, nitro or nitrile; M1 and M2 are independently selected from Mg(II),
Zn(II), Cr(II), Cr(III)-X, Co(II), Co(III)-X, Mn(II), Ni(II), Ni(III)-X, Fe(II), and Fe(III)-
X, preferably M1 and M2 are independently selected from Mg(II), Ni(II), Ni(III)-X
and Zn(II). Preferably M1 and M2 are the same, and are selected from Ni(II) or
Mg(II).
Preferably, both occurrences of R1 are the same, and are selected from
hydrogen, halide, amino, nitro, sulfoxide, sulfonyl, sulfinate, silyl, silyl ether and
an optionally substituted alkyl, alkenyl, aryl, heteroaryl, alkoxy, aryloxy or
alkylthio; R2 is hydrogen; R3A is a substituted or unsubstituted cycloalkylene or
alkylene and R3B is a substituted or unsubstituted alkylene or arylene; each
occurrence of E3 to E6 is NR4; R4 is hydrogen; each X is the same, and is
selected from OC(O)Rx
, ORx
, halide, carbonate, amino, nitro, alkyl, aryl,
heteroaryl, phosphinate or OSO2R
x
, Rx
is alkyl, alkenyl, alkynyl, heteroalkyl, aryl,
heteroaryl or alkylaryl; Rx
is alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl or
alkylaryl; each G (where present) is independently selected from halide; water; a
heteroaryl optionally substituted by alkyl, alkenyl, alkynyl, alkoxy, halogen,
hydroxyl, nitro or nitrile; M1 and M2 are independently selected from Mg(II),
Zn(II), Cr(II), Cr(III)-X, Co(II), Co(III)-X, Mn(II), Ni(II), Ni(III)-X, Fe(II), and Fe(III)-
X, preferably M1 and M2 are independently selected from Mg(II), Ni(II), Ni(III)-X
and Zn(II). Still more preferably M1 and M2 are independently selected from
32
Ni(II), Ni(III), or Mg(II). Preferably M1 and M2 are the same, and are selected
from Ni(II) or Mg(II).
Preferably, both occurrences of R1 are the same, and are selected from
hydrogen, halide, amino, nitro, sulfoxide, sulfonyl, sulfinate, silyl, silyl ether and
an optionally substituted alkyl, alkenyl, aryl, heteroaryl, alkoxy, aryloxy or
alkylthio; R2 is hydrogen; R3A and R3B are the same and are substituted or
unsubstituted alkylene; each of E3, E4, E5 and E6 is NR4 wherein one of the R4
groups is different from a remaining R4 group and is selected from an optionally
substituted alkyl or heteroalkyl and the remaining R4 group/s are hydrogen; each
X is the same, and is selected from OC(O)Rx
, ORx
, halide, carbonate, amino,
nitro, alkyl, aryl, heteroaryl, phosphinate or OSO2R
x
, Rx
is alkyl, alkenyl, alkynyl,
heteroalkyl, aryl, heteroaryl or alkylaryl; Rx
is alkyl, alkenyl, alkynyl, heteroalkyl,
aryl, heteroaryl or alkylaryl; each G (where present) is independently selected
from halide; water; a heteroaryl optionally substituted by alkyl, alkenyl, alkynyl,
alkoxy, halogen, hydroxyl, nitro or nitrile; M1 and M2 are independently selected
from Mg(II), Zn(II), Cr(II), Cr(III)-X, Co(II), Co(III)-X, Mn(II), Ni(II), Ni(III)-X, Fe(II),
and Fe(III)-X, preferably M1 and M2 are independently selected from Mg(II),
Ni(II), Ni(III)-X and Zn(II). Still more preferably M1 and M2 are independently
selected from Ni(II), Ni(III), or Mg(II). Preferably M1 and M2 are the same, and
are selected from Ni(II) or Mg(II).
Preferably both occurrences of R1 are the same, and are selected from
hydrogen, halide, amino, nitro, sulfoxide, sulfonyl, sulfinate, silyl, silyl ether and
an optionally substituted alkyl, alkenyl, aryl, heteroaryl, alkoxy, aryloxy or
alkylthio; R2 is hydrogen; R3A and R3B are selected from substituted or
unsubstituted alkylene, substituted or unsubstituted cycloalkylene and
substituted or unsubstituted arylene; E3 to E6 are selected from N, NR4, S or O;
R4 is selected from hydrogen, or optionally substituted alkyl or heteroalkyl; each
X is the same, and is selected from OC(O)Rx
, ORx
, or OSO2R
x
, Rx
is alkyl,
alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl or alkylaryl; each G (where present)
is independently selected from halide; water; a heteroaryl optionally substituted
by alkyl, alkenyl, alkynyl, alkoxy, halogen, hydroxyl, nitro or nitrile; M1 and M2 are
independently selected from Mg(II), Zn(II), Cr(II), Cr(III)-X, Co(II), Co(III)-X,
33
Mn(II), Ni(II), Ni(III)-X, Fe(II), and Fe(III)-X, preferably M1 and M2 are
independently selected from Mg(II), Ni(II), Ni(III)-X and Zn(II). Still more
preferably M1 and M2 are independently selected from Ni(II), Ni(III), or Mg(II).
Preferably M1 and M2 are the same, and are selected from Ni(II) or Mg(II);
wherein:
i) R3A is different from R3B; and/or
ii) at least one occurrence of E3, E4, E5 and E6 is different to a
remaining occurrence of E3, E4, E5 and E6.
More preferably, both occurrences of R1 are the same, and are selected from an
optionally substituted alkyl; R2 is hydrogen; R3A and R3B are selected from
substituted or unsubstituted alkylene, substituted or unsubstituted cycloalkylene,
and substituted or unsubstituted arylene; each occurrence of E3 to E6 is NR4; R4
is selected from hydrogen, or optionally substituted alkyl or heteroalkyl; each X is
the same, and is selected from OC(O)Rx
, ORx
, or OSO2R
x
, Rx
is alkyl, alkenyl,
alkynyl, heteroalkyl, aryl, heteroaryl or alkylaryl; M1 and M2 are independently
selected from Mg(II), Ni(II), Ni(III)-X and Zn(II). Still more preferably M1 and M2
are independently selected from Ni(II), Ni(III), or Mg(II). Preferably M1 and M2
are the same, and are selected from Ni(II) or Mg(II); wherein:
i) R3A is different from R3B; and/or
ii) at least one occurrence of E3, E4, E5 and E6 is different to a
remaining occurrence of E3, E4, E5 and E6.
Still more preferably, both occurrences of R1 are the same, and are tertiary butyl
; R2 is hydrogen; R3A and R3B are selected from butylene, benzylene, ethylene,
propylene, 2,2-dimethylpropylene; each occurrence of E3 to E6 is NR4; R4 is
selected from hydrogen, methyl, ethyl, propyl, butyl, or –alkyl-C(O)-OR19 as
defined hereinabove, preferably methyl propanoate; each X is the same, and is
OAc; M1 and M2 are independently selected from Mg(II), Ni(II), Ni(III)-X and
Zn(II). Still more preferably M1 and M2 are independently selected from Ni(II),
Ni(III), or Mg(II). Preferably M1 and M2 are the same, and are selected from Ni(II)
orMg(II); wherein:
i) R3A is different from R3B; and/or
34
ii) at least one occurrence of E3, E4, E5 and E6 is different to a
remaining occurrence of E3, E4, E5 and E6.
Exemplary catalysts of the first aspect are as follows:
, , ,
35
36
37
More preferably the catalyst of formula (I) is:
38
In the second aspect of the invention, there is provided a ligand of formula (II):
(II)
wherein:
R1 and R2 are independently selected from hydrogen, halide, a nitro group, a
nitrile group, an imine, an amine, an ether group, a silyl group, a silyl ether
group, a sulfoxide group, a sulfonyl group, a sulfinate group or an acetylide
group or an optionally substituted alkyl, alkenyl, alkynyl, haloalkyl, aryl,
heteroaryl, alkoxy, aryloxy, alkylthio, arylthio, alicyclic or heteroalicyclic group;
R3A and R3B are independently selected from optionally substituted alkylene,
alkenylene, alkynylene, heteroalkylene, heteroalkenylene, heteroalkynylene,
39
arylene, heteroarylene or cycloalkylene, wherein alkylene, alkenylene,
alkynylene, heteroalkylene, heteroalkenylene and heteroalkynylene, may
optionally be interrupted by aryl, heteroaryl, alicyclic or heteroalicyclic;
R5 is independently selected from H, or optionally substituted aliphatic,
heteroaliphatic, alicyclic, heteroalicyclic, aryl, heteroaryl, alkylheteroaryl or
alkylaryl;
E1 is C, E2 is OY, S or NH or E1 is N and E2 is O;
Y is hydrogen or an alkali metal;
E3, E4, E5 and E6 are each independently selected from N, NR4, O and S,
wherein when any of E3, E4, E5 or E6 are N, is , and wherein when
any of E3, E4, E5 or E6 are NR4, O or S, is ; R4 is independently
selected from H, or optionally substituted aliphatic, heteroaliphatic, alicyclic,
heteroalicyclic, aryl, heteroaryl, alkylheteroaryl or alkylaryl;
and wherein:
i) R3A is different from R3B; and/or
ii) at least one occurrence of E3, E4, E5 and E6 is different to a remaining
occurrence of E3, E4, E5 and E6.
All of the preferred features defined hereinabove in relation to the first aspect
apply in relation to the second aspect. In particular, all of the preferred features
in relation to the groups R1, R2, R3A, R3B, R4, R5, E1, E2, E3, E4, E5, and E6 apply
equally to the second aspect.
Preferably Y is selected from hydrogen, lithium, sodium, potassium, rubidium,
caesium, or francium. More preferably Y is either hydrogen or lithium.
Preferably both occurrences of R1 are the same, and are selected from
hydrogen, halide, amino, nitro, sulfoxide, sulfonyl, sulfinate, silyl, silyl ether and
an optionally substituted alkyl, alkenyl, aryl, heteroaryl, alkoxy, aryloxy or
alkylthio; R2 is hydrogen; R3A and R3B are selected from substituted or
unsubstituted alkylene, substituted or unsubstituted cycloalkylene and
substituted or unsubstituted arylene; E3 to E6 are N, NR4, S or O; R4 is selected
from hydrogen, or optionally substituted alkyl or heteroalkyl;
40
wherein:
iii) R3A is different from R3B; and/or
iv) at least one occurrence of E3, E4, E5 and E6 is different to a
remaining occurrence of E3, E4, E5 and E6.
More preferably, both occurrences of R1 are the same, and are selected from an
optionally substituted alkyl; R2 is hydrogen; R3A and R3B are selected from
substituted or unsubstituted alkylene, substituted or unsubstituted cycloalkylene,
and substituted or unsubstituted arylene; each occurrence of E3 to E6 is NR4; R4
is selected from hydrogen, or optionally substituted alkyl or heteroalkyl;
wherein:
i) R3A is different from R3B; and/or
ii) at least one occurrence of E3, E4, E5 and E6 is different to a
remaining occurrence of E3, E4, E5 and E6.
Still more preferably, both occurrences of R1 are the same and are tertiary butyl ;
R2 is hydrogen; R3A and R3B are selected from tertiary butylene, benzylene,
ethylene, propylene, 2,2-dimethylpropylene; each occurrence of E3 to E6 is NR4;
R4 is selected from hydrogen, methyl, ethyl, propyl, butyl, or–alkyl-C(O)-OR19 as
defined hereinabove, preferably methyl propanoate ;
wherein:
i) R3A is different from R3B; and/or
ii) at least one occurrence of E3, E4, E5 and E6 is different to a
remaining occurrence of E3, E4, E5 and E6.
More preferably still, the ligand of formula (II) is:
41
(IIa)
wherein:
R1 is tertiary butyl; R2 is hydrogen; R3 is 2,2-dimethylpropylene; and R4 is
selected from methyl, ethyl, propyl, or butyl;
or the ligand of formula (II) is:
(IIb)
or the ligand of formula (II) is:
(IIc)
or the ligand of formula (II) is:
42
(IId)
or the ligand of formula (II) is:
(IIe)
wherein:
R3 is selected from 2,2-dimethylpropylene, propylene, or ethylene;
or the ligand of formula (II) is:
(IIf)
or the ligand of formula (II) is:
43
(IIg)
or the ligand of formula (II) is:
(IIh)
wherein:
R is methyl or hydrogen;
or the ligand of formula (II) is:
(IIi)
or the ligand of formula (II) is:
44
(IIj)
wherein:
R1 is tertiary butyl; R2 is hydrogen; R3 is 2,2-dimethylpropylene; and R4 is methyl,
ethyl, propyl, or butyl. Preferably R4 is methyl.
More preferably still, the ligand of formula (II) comprises at least one Nsubstituent,
and may be selected from:
(IIa)
wherein:
R1 is tertiary butyl; R2 is hydrogen; R3 is 2,2-dimethylpropylene; and R4 is
selected from methyl, ethyl, propyl, or butyl;
or:
45
(IIg)
or:
(IIh)
or:
(IIj)
Wherein
R1 is tertiary butyl; R2 is hydrogen; R3 is 2,2-dimethylpropylene; and R4 is methyl,
ethyl, propyl, or butyl. Preferably R4 is methyl.
46
In the third aspect, the invention extends to methods of preparation of ligands,
complexes and catalysts according to the second aspect and first aspect
respectively or as otherwise defined herein.
In the fourth aspect of the present invention, there is provided a process of
asymmetric N-substitution of a symmetrical ligand having a tetraaminophenol
coordination sphere, the process comprising the following steps:
a) protecting at least two of the amino groups of the coordination sphere of
the symmetrical ligand with an optionally substituted alkylene;
b) asymmetrically N-substituting one or more of the protected amino groups
of the product of step (a) with a substituent.
Preferably the symmetrical ligand comprises formula (IV):
(IV)
wherein:
R1 and R2 are as defined above in relation to the second aspect, and R3 is
defined as R3A or R3B in relation to the second aspect.
More preferably therefore, the symmetrical ligand of formula (IVa) is:
47
(IVa)
Preferably the optionally substituted alkylene is selected from an optionally
substituted methylene or ethylene.
Preferably the optionally substituted alkylene is derived from a protecting
reagent. Preferably therefore step (a) comprises reacting the symmetrical ligand
with a protecting reagent comprising an optionally substituted alkyl group.
Preferably the protecting reagent is an aldehyde, more preferably an aldehyde
selected from formaldehyde or benzaldehyde.
Preferably step (a) comprises protecting two or more of the amino groups of the
coordination sphere of the symmetrical ligand by forming bridging groups
between the adjacent amino or phenolic groups. Preferably the bridging groups
are the optionally substituted alkylene, and are selected from an optionally
substituted methylene or ethylene.
Preferably the product of step (a) comprises a pair of optionally substituted
alkylene bridges between adjacent nitrogen atoms of the coordination sphere.
Preferably step (a) is conducted in the presence of a solvent which may be any
suitable solvent for the protecting reagent, for example methanol or THF.
Preferably step (a) comprises contact with the protecting reagent for sufficient
time to complete or substantially complete the reaction. Suitable contact times
48
are between 30 minutes and 15 hours, more preferably for between 2 hours and
8 hours, most preferably for around 6 hours.
Preferably step (a) is conducted at a suitable temperature. Suitable
temperatures may be in the range -25 to 75°C, for example 0 to 50°C, typically
15-30°C such as room temperature (around 21°C).
Preferably step (b) comprises asymmetrically N-substituting one or more of the
protected amino groups of the product of step (a) with an N-substituting agent by
for example hydroamination with an alkene (such as an acrylate or acrylonitrile)
or by using an alkylating agent.
Preferably the substituent is an R4 group, as defined hereinabove. Preferably
therefore, one or more of the amino groups is substituted to form an NR4 group.
Preferably step (b) comprises asymmetrically N-substituting one or more of the
protected amino groups of the product of step (a) with a substituent. More
preferably step (b) comprises asymmetrically N-substituting one or more of the
protected amino groups of the product of step (a) with a substituent by reacting
the product of step (a) with an N-substituting agent.
Preferably the N-substituting agent is an alkylating agent or an alkene such as
an activated alkene for example an alkyl acrylate, alkyl methacrylate, alkyl vinyl
ketone or acrylonitrile, more preferably the alkylating agent comprises the
formula R4X. Preferably X is a halide, tosylate or triflate, more preferably X is
iodine. In one preferred embodiment, R4X is selected from iodomethane,
iodoethane, 1-iodopropane or 1-iodobutane.
Preferably step (b) is conducted in the presence of a solvent which may be any
suitable solvent for N-substituting agent ,for example methanol,
dichloromethane, or THF.
Preferably step (b) comprises contact with the N-substituting agent for sufficient
time to complete or substantially complete the reaction. Suitable contact times
49
are between 12 and 22 hours, more preferably between 14 and 18 hours, most
preferably for around 16 hours.
Preferably step (b) is conducted at a suitable temperature. Suitable
temperatures may be between 20°C to 90°C, more preferably between 23°C to
80°C, most preferably at around 25-50°C.

The method may further comprise step (c) hydrolysing the optionally substituted
alkylene bridging groups between the adjacent amino groups.
Preferably the hydrolysing of step (c) is performed by reacting the product of
step (b) with an acid, more preferably with HCl and subsequently isolating the
material
Optionally, the method may further comprise upstream steps of formation of the
symmetrical ligand having a tetraaminophenol coordination sphere.
Preferably the method further comprises upstream steps of formation of the
symmetrical ligand comprising formula (IV):
(IV)
wherein:
R1 and R2 are as defined above in relation to the second aspect, and R3 is
defined as R3A or R3B in relation to the second aspect.
More preferably therefore, the method further comprises upstream steps of
formation of the symmetrical ligand comprising formula (IVa):
50
(IVa)
Preferably the upstream steps comprise (1) formation of a symmetrical ligand
having a tetraiminophenol coordination sphere, and (2) reduction of the imine
groups to amine groups.
Preferably upstream step (1) comprises formation of a symmetrical ligand having
a tetraiminophenol coordination sphere from a compound of formula (III):
(III)
wherein R1 and R2 are as defined hereinabove.
More preferably upstream step (1) comprises reacting a compound of formula
(III) with an amine of formula H2N-R3-NH2, wherein R3 is as defined hereinabove.
Upstream step (1) may be conducted in the presence of a suitable solvent, an
acid and an electrolyte.
The solvent may be any suitable solvent for the reactants of upstream step (1) ,
for example methanol or THF. More preferably the solvent is methanol.
51
Preferably upstream step (2) comprises reacting the product of upstream step
(1) with a reducing agent.
Suitable reducing agents are known to those skilled in the art, for example
sodium borohydride or hydrogen.
Preferably upstream step (2) is conducted in the presence of a solvent, which
may be any suitable solvent for the reactants of upstream step (2), for example
methanol or THF. More preferably the solvent is methanol.
In one preferred embodiment, the process comprises the following steps:
(a) forming a symmetrical ligand having a tetraiminophenol coordination
sphere;
(b) reducing the imino groups of the product of step (a) to amino groups;
(c) protecting the amino groups of the product of step (b) with an
optionally substituted alkylene;
(d) asymmetrically N-substituting one or more of the protected amino
groups of the product of step (c) with a substituent;
(e) hydrolysing the optionally substituted alkylene groups of the product
of step (d) to remove the alkylene bridging group;
(f) optional neutralisation of the product of step (e).
In a more preferred embodiment, the process comprises the following steps:
(a) reacting a compound of formula (III) with an amine of formula H2N-R3-
NH2 to form a ligand having a tetraiminophenol coordination sphere;
(III)
(b) reducing the imino groups of the product of step (a) to amino groups;
52
(c) protecting the amino groups of the product of step (b) by forming
bridging groups between the adjacent amino groups, wherein the
bridging groups are optionally substituted alkylenes;
(d) asymmetrically N-substituting one or more of the protected amino
groups of the product of step (c) with an N-substituting agent;
(e) hydrolysing the optionally substituted alkylene groups of the product
of step (d);;
(f) optional neutralisation of the product of step (e);
wherein R1, R2, R3, R4 and X are as defined in relation to the second
aspect.
Preferably the asymmetrical ligand produced is that according to the second
aspect.
Preferably, the ligand according to the second aspect is that of formula (IIa):
(IIIa)
wherein:
R1 is tertiary butyl; R2 is hydrogen; R3 is2,2-dimethylpropylene; and R4 is
selected from methyl, ethyl, propyl, or butyl.
Preferably in formula IV, R1 is tertiary butyl; R2 is hydrogen; R3 is 2,2-
dimethylpropylene.
In a fifth aspect of the invention, the catalysts of the first aspect are capable of
polymerising (i) carbon dioxide and an epoxide, (ii) an epoxide and an
anhydride, and (iii) a lactide and/or a lactone. Therefore, in a fifth aspect of the
53
invention there is provided a process for the reaction of carbon dioxide with an
epoxide, an anhydride with an epoxide, or a lactide and/or a lactone in the
presence of a catalyst according to the first aspect.
The process of the fifth aspect may be carried out in the presence of a chain
transfer agent. Suitable chain transfer agents include the chain transfer agents,
for example as defined by formula (II), in WO 2013/034750, the entire contents
of which are hereby incorporated by reference. For example, the chain transfer
agent may be water, or may comprise at least one amine (-NHR), alcohol (-OH)
or thiol (-SH) moiety.
Examples of chain transfer agents useful in the second aspect include water,
mono-alcohols (i.e. alcohols with one OH group, for example, 4-
ethylbenzenesulfonic acid, methanol, ethanol, propanol, butanol, pentanol,
hexanol, phenol, cyclohexanol), diols (for example, 1,2-ethanediol, 1-2-
propanediol, 1,3-propanediol, 1,2-butanediol, 1-3-butanediol, 1,4-butanediol, 1,5-
pentanediol, 1,6-hexanediol, 1,2-diphenol, 1,3-diphenol, 1,4-diphenol, catechol
and cyclohexenediol), triols (glycerol, benzenetriol, 1,2,4-butanetriol,
tris(methylalcohol)propane, tris(methylalcohol)ethane,
tris(methylalcohol)nitropropane, trimethylolpropane, preferably glycerol or
benzenetriol), tetraols (for example, calix[4]arene, 2,2-bis(methylalcohol)-1,3-
propanediol, di(trimethylolpropane)), polyols (for example, D-(+)-glucose,
dipentaerythritol or D-sorbitol), dihydroxy terminated polyesters (for example
polylactic acid), dihydroxy terminated polyethers (for example poly(ethylene
glycol)), acids (such as diphenylphosphinic acid), starch, lignin, mono-amines
(i.e. methylamine, dimethylamine, ethylamine, diethylamine, propylamine,
dipropylamine, butylamine, dibutylamine, pentylamine, dipentylamine,
hexylamine, dihexylamine), diamines (for example1,4-butanediamine), triamines,
diamine terminated polyethers, diamine terminated polyesters, mono-carboxylic
acids (for example, 3,5-di-tert-butylbenzoic acid), dicarboxylic acids (for
example, maleic acid, malonic acid, succinic acid, glutaric acid or terephthalic
acid, preferably maleic acid, malonic acid, succinic acid, glutaric acid),
tricarboxylic acids (for example, citric acid, 1,3,5-benzenetricarboxylic acid or
1,3,5-cyclohexanetricarboxylic acid, preferably citric acid), mono-thiols, dithoils,
54
trithiols, and compounds having a mixture of hydroxyl, amine, carboxylic acid
and thiol groups, for example lactic acid, glycolic acid, 3-hydroxypropionic acid,
natural amino acids, unnatural amino acids, monosaccharides, disaccharides,
oligosaccharides and polysaccharides (including pyranose and furanose forms).
Preferably, the chain transfer agent is selected from cyclohexene diol, 1,2,4-
butanetriol, tris(methylalcohol)propane, tri(methylalcohol)propane,
tri(methylalcohol)butane, pentaerythritol, poly(propylene glycol), glycerol, monoand
di- ethylene glycol, propylene glycol, tris(methylalcohol)nitropropane,
tris(methylalcohol)ethane, 2,2-bis(methylalcohol)-1,3-propanediol, 1,3,5-
benzenetricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid, 1,4-
butanediamine, 1,6-hexanediol, D-sorbitol, 1-butylamine, terephthalic acid, D-
(+)-glucose, 3,5-di-tert-butylbenzoic acid, and water.
The process of the fifth aspect may be carried out in the presence of a solvent.
Examples of solvents useful in the third aspect include toluene, diethyl
carbonate, dimethyl carbonate, dioxane, dichlorobenzene, methylene chloride,
propylene carbonate, ethylene carbonate, acetone, ethyl acetate,
tetrahydrofuran (THF), etc.
When the process of the fifth aspect involves the reaction of an epoxide, the
epoxide may be any compound comprising an epoxide moiety. The epoxide
may be purified (for example by distillation, such as over calcium hydride) prior
to reaction with carbon dioxide or the anhydride. For example, the epoxide may
be distilled prior to being added to the reaction mixture comprising the catalyst.
The process of the fifth aspect of the invention may be carried out at a pressure
of 1 to 100 atmospheres, preferably at 1 to 40 atmospheres, such as at 1 to 20
atmospheres, more preferably at 1 or 10 atmospheres. The catalysts used in
the process of the second aspect allow the reaction to be carried out at low
pressures.
The process of the fifth aspect of the invention may be carried out at a
temperature of about 0ºC to about 250ºC, preferably from about 40°C to about
160°C, even more preferably from about 50˚C to about 120˚C. The duration of
55
the process may be up to 168 hours, such as from about 1 minute to about 24
hours, for example from about 5 minutes to about 12 hours, e.g. from about 1 to
about 6 hours.
The process temperature, for copolymerisations of carbon dioxide and an
epoxide, may be used to control the product composition. When the temperature
of the process of the fifth aspect which involves reacting carbon dioxide and an
epoxide is increased, the selectivity of the catalyst towards the formation of
cyclic carbonate is also increased. The catalysts and processes may operate at
temperatures up to 250°C.
The process of the fifth aspect of the invention may be carried out at low
catalytic loading. For example, when the reaction involves copolymerisation of
carbon dioxide and an epoxide, the catalytic loading for the process is preferably
in the range of 1:1,000-300,000 catalyst:epoxide, more preferably in the region
of 1:10,000-100,000 catalyst:epoxide, even more preferably in the region of
1:50,000-100,000 catalyst:epoxide. When the process involves copolymerisation
of an epoxide and an anhydride, or the reaction of a lactide and/or lactone, the
catalytic loading for the process is preferably in the range of 1:1,000-300,000
catalyst: total monomer content, more preferably in the region of 1:10,000-
100,000 catalyst: total monomer content, even more preferably in the region of
1:50,000-100,000 catalyst:total monomer content. The ratios above are molar
ratios.
The catalysts of the first aspect, and in particular catalysts wherein both M1 and
M2 are selected from Ni(II) and Mg(II), have high activity and selectivity for
producing polycarbonates by reacting carbon dioxide and an epoxide, optionally
in the presence of a chain transfer agent, and preferably at temperatures
between about 40°C to about 160°C. Thus, the reaction times for the process of
the second aspect can be less than 12 hours, and preferably from about 2 to
about 6 hours.
The process of the fifth aspect can be carried out in a batch reactor or a
continuous reactor.
56
It will be appreciated that the various features described above for the process of
the fifth aspect may be present in combination mutatis mutandis. All preferred
features of the first aspect apply equally to the fifth aspect and may be present in
combination mutatis mutandis.
The sixth aspect of the invention provides a product of the process of the fifth
aspect of the invention. All preferred features of the fifth aspect of the invention
apply to the sixth aspect of the invention mutatis mutandis.
When the process of the fifth aspect is carried out in the presence of a chain
transfer agent, it produces polymer chains which are terminated at substantially
all ends with hydroxyl groups (i.e. polycarbonate polyols or polyester polyols). By
“substantially”, it is meant that at least 90% of the resultant polymer chains,
preferably at least 95% of the resultant polymer chains, and even more
preferably at least 98%, and even more preferably at least about 99% of the
resultant polymer chains are terminated at all ends in hydroxyl groups. In order
for at least 90% of the resultant polymer chains to be terminated at all ends with
hydroxyl groups, it is preferred for the process of the second aspect to be carried
out in the presence of at least about 4 equivalents of chain transfer agent,
relative to the amount of catalyst. In order for at least 95% of the resultant
polymer chains to be terminated at all ends with hydroxyl groups, it is preferred
for the process of the second aspect to be carried out in the presence of at least
about 10 equivalents of chain transfer agent, relative to the amount of catalyst.
In order for at least 98% of the resultant polymer chains to be terminated at all
ends with hydroxyl groups, it is preferred for the process of the fifthaspect to be
carried out in the presence of at least about 20 equivalents of chain transfer
agent, relative to the amount of catalyst. Thus, polyols obtained by the process
of the fifth aspect are considered to form part of the sixth aspect of the
invention.
The chain transfer agent referred to in the fifth aspect may be used to control the
molecular weight (Mn) of the polymer products of the sixth aspect. Preferably,
the molecular weight (Mn) of the polymer products of the sixth aspect is greater
57
than about 200 g/mol. The molecular weight (Mn) of the polymer products of the
sixth aspect may be from about 200 g/mol to about 200,000 g/mol. The
molecular weight of the polymers produced by the fifth aspect can be measured
by Gel Permeation Chromatography (GPC) using, for example, a GPC-60
manufactured by Polymer Labs, using THF as the eluent at a flow rate of 1
ml/min on Mixed B columns, manufactured by Polymer Labs. Narrow molecular
weight polystyrene standards can be used to calibrate the instrument.
It is possible to produce polycarbonate polyols and polyester polyols having a Mn
of from about 200 g/mol to about 20,000 g/mol, preferably less than about
10,000 g/mol by adding a chain transfer agent to the process of the fifth aspect.
It is also possible to produce polymers having a Mn of greater than about 20,000
g/mol from the process of the fifth aspect. Preferably, the polymer having a Mn of
greater than about 20,000 g/mol is a polycarbonate or a polyester, even more
preferably a polycarbonate. Preferably, the polymer having a Mn of greater than
about 20,000 g/mol is a polycarbonate and is produced carrying out the process
of the fifth aspect without adding a chain transfer agent (CTA).
The polymers produced by the fifth aspect may be produced to have a
polydispersity index (PDI) of less than about 2, more preferably less than about
1.5, and even more preferably less than about 1.2. Furthermore, it is possible to
control the molecular weight distribution so as to produce multi-modal or broad
molecular weight distribution polymers by addition of one or more chain transfer
agent(s).
The polymers produced by the process of the fifth aspect (e.g. polycarbonates
such as PCHC or PPC), are useful building blocks in the preparation of various
copolymeric materials. The polymers produced by the process of the fifth aspect
may undergo further reaction, for example to produce polymeric products such
as polyureas or polyamines. These processes and reactions are well known to
the skilled person (for example, refer to WO2013/034750).
58
The polycarbonate or polyester polyols produced by the process of the fifth
aspect may be used in various applications and products which conventionally
use polyols, including adhesives (such as hot melt adhesives and structural
adhesives), a binder (such as forest product binders, foundry core binders and
rubber crumb binders), coatings (such as powder coatings, transport, e.g.
automotive or marine coatings, fast cure coatings, self-healing coatings, top
coats and primers, varnishes, and coatings for marine applications, e.g. oil rigs),
elastomers (such as cast elastomers, fibres/spandex elastomers, footwear
elastomers, RIM/RRIM elastomers, synthetic leather elastomers, technical
microcellular elastomers and TPU elastomers), flexible foams (such as
viscoelastic foams), rigid foams (such as rigid and flexible panels, moulded rigid
foams, aerosol gap filling foam, spray foams, refrigeration foams, pour-in-place
foams, and foam slabs) and sealants (such as glazing sealants for commercial,
industrial and transport (e.g. automotive) applications, and construction
sealants). The polyamines and polyureas can be processed using methods
standard techniques known in the art, such as foaming.
It will be understood that the polycarbonate and polyester polyols produced by
the process of the fifth aspect may be mixed with other polyols prior to further
use or reaction.
The polycarbonates, and in particular, polycarbonates having a Mn of greater
than about 20,000 g/mol (e.g. produced without adding chain transfer agent to
the process of the fifth aspect) may have a number of beneficial properties
including high strength, high toughness, high gloss, high transparency, low haze,
high gas (e.g. oxygen and carbon dioxide) or water barrier properties, flame
resistance, UV resistance, high durability, rigidity and stiffness, compatibility with
plasticizers, broad dimensional stability temperature, biodegradability and
biocompatibility, and modulus of elasticity and yield strength comparable to
LDPE. Thus, these polymers may be used in various applications and products,
such as electronic components, construction materials, data storage products,
automotive and aircraft products, security components, medical applications,
mobile phones, packaging (including bottles), optical applications (such as safety
glass, windscreens, etc).
59
Example
Example 1: Synthesis of asymmetric ligands H2L
1-4
Ligands H2L
1-4 were prepared by the following method:
A tetraaminophenol ligand may be formed by the following process (steps 1 and
2):
To a round-bottomed flask was added 4-tert-butyl-2,6-diformylphenol (1.20 g,
5.80 mmol), NaClO4 (2.81 g, 23.2 mmol), acetic acid (0.66 mL, 11.6 mmol) and
methanol (90 mL). This solution was heated to 70 °C whilst stirring, as the
solution started to boil, 2,2-dimethyl-1,3- propanediamine (0.70 mL, 5.8 mmol)
was added slowly in methanol (30 mL). The yellow reaction mixture was allowed
to cool to room temperature, and left stirring for 24 hours, after which a bright
orange precipitate was filtered and washed with cold (-78 °C) methanol (1.85 g,
95 %). The product was suspended in methanol (180 mL). The suspension was
cooled to 0 °C and NaBH4 (2.65 g, 69.9 mmol) was added slowly. As NaBH4 was
added, the red-orange suspension turned to a clear solution. Water was added
slowly, and the solution turned cloudy. Once precipitate started to form, the
mixture was left overnight and H2L
11 was filtered off as a white solid (1.21 g, 88
%).
60
To a solution of the resulting product (20.8 mmol) in methanol (500 mL) was
added a formaldehyde solution (37% in water, 104 mmol) at room temperature
(RT). The reaction was stirred at RT for 15 h after which the reaction mixture
was filtered and the filter cake was washed with MeOH and water. The resultant
white powder was transferred to a round bottom flask. Toluene was added and
evaporated under reduced pressure to azeotrope off the residual water giving
the desired product as a white powder (17.2 mmol). R4X (iodomethane,
iodoethane, 1-iodopropane or 1-iodobutane, 104 mmol) was added to a stirred
solution of this white powder (10.4 mmol) in anhydrous THF (120 mL) at 25 °C
until the reaction was deemed to be complete. A white precipitate formed in the
reaction mixture and was collected by suction filtration. The filter cake was
washed with THF. The resultant white powder was transferred to a round bottom
flask and dried under high vacuum for several hours. This was dissolved (7.3
mmol) in MeOH and concentrated HCl(aq) (1:1) and placed in a heating block set
to 75°C whilst refluxing and stirred for 15 h. After this time, the slightly yellow
solution was allowed to cool to RT and was neutralized with a saturated aqueous
solution of K2CO3, inducing the product to precipitate out of solution as a white
solid. This solid was collected and dried.
H2L
1
:
1H NMR (400 MHz, CDCl3) δ 7.05 (d, J = 2.4 Hz, 1H), 7.02 (d, J = 2.4 Hz,
1H), 6.89 (d, J = 2.5 Hz, 1H), 6.85 (d, J = 2.5 Hz, 1H), 3.74 (s, 2H), 3.61 (s, 2H),
3.54 (s, 2H), 3.51 (s, 2H), 2.50 (s, 2H), 2.39 (s, 2H), 2.37 (s, 2H), 2.29 (s, 2H),
2.27 (s, 3H), 1.30(3) (s, 9H), 1.29(6) (s, 9H), 0.93 (s, 6H), 0.92 (s, 6H).
MS (ESI) m/z: 567.5 ([M+H]+
, 100 %).
H2L
2
:
1H NMR (400 MHz, CDCl3) δ 7.08 (m, 2H), 6.87 (m, 2H), 3.77 (s, 2H), 3.58
(s, 2H), 3.53 (s, 4H), 2.55 (s, 2H), 2.53 (q, J = 7.0 Hz, 2H), 2.41 (s, 2H), 2.33 (s,
4H), 1.34 (s, 9H), 1.33 (s, 9H), 1.07 (t, J = 7.0 Hz, 3H), 0.94 (s, 6H), 0.92 (s, 6H).
MS (ESI) m/z: 581.5 ([M+H]+
, 100 %).
H2L
3
: 1H NMR (400 MHz, CDCl3) δ 7.11 (m, 2H), 6.84 (m, 2H), 3.76 (s, 2H), 3.52
(s, 2H), 3.50 (m, 4H), 2.54 (s, 2H), 2.48 (m, 2H), 2.38 (s, 2H), 2.32 (s, 2H), 2.30
(s, 2H), 2.20 (s, 2H), 1.59 (m, 2H), 1.34 (s, 18H), 0.93 (s, 6H), 0.91 (s, 6H).
MS (ESI) m/z: 595.5 ([M+H]+
, 100 %), 581.5 ([M-CH3+H]+
, 30 %).
61
H2L
4
: 1H NMR (400 MHz, CDCl3) δ 7.11 (m, 2H), 6.83 (m, 2H), 3.75 (s, 2H), 3.51
(m, 6H), 2.53 (s, 2H), 2.49 (m, 2H), 2.38 (s, 2H), 2.32 (s, 2H), 2.30 (s, 2H), 1.55
(m, 2H), 1.34 (s, 18H), 0.94 (q, J = 7.3 Hz, 3H), 0.93 (s, 6H), 0.91 (s, 6H).
MS (ESI) m/z: 609.5 ([M+H]+
, 100 %), 595.5 ([M-CH3+H]+
, 10 %), 581.5 ([MCH2CH3+H]+
, 10 %).
Example 2: synthesis of asymmetric ligand H2L
5
4-tert-butyl-2,6-diformylphenol (4 mmol) and 1,3-diamino-2,2-dimethylpropane (2
mmol) were each dissolved in EtOH (15 mL and 10 mL respectively). The
solutions were warmed to boiling then the solution of amine added dropwise with
stirring giving an immediate colour change to a deeper yellow. After stirring
overnight the precipitate was collected, washed with cold ethanol (2 x 5mL),
pentane (1 x 5 mL) then dried under vacuum, giving 4.
1H NMR (CDCl3) δ: 14.45
(br s, 2H), 10.56 (s, 2H), 8.45 (s, 2H), 7.94 (s, 2H), 7.55 (s, 2H), 3.58 (s, 4H),
1.34 (s, 18H), 1.15 (s, 6H).
4 (0.4 mmol) was dissolved in THF (10 mL) and treated with LiHMDS (0.8 mmol)
in THF (3 mL) causing the bright yellow solution to change to a greenish yellow
solution. After 30 mins a solution of 1,2-diaminobenzene (0.4 mmol) was added
in THF (10 mL) over 10 mins with rapid stirring. After stirring overnight the colour
had again returned to bright yellow. The solution was concentrated to 2 mL and
layered with heptane (10 mL) and allowed to stand. The yellow solid that
precipitated after 1 day was collected and washed with pentane (2 x 5 mL) then
62
dried under vacuum. . 1H NMR (CDCl3) δ: 9.51 (s, 2H), 7.91 (s, 2H), 7.45 (d, 2H),
7.38 (d, 2H), 6.74 (s, 4H), 3.4 (br s, 4H), 1.34 (s, 18H), 0.62 (s, 6H).
5 (0.2 mmol) was dissolved in dry MeOH (25 mL) under nitrogen in a dried 3-
neck round-bottomed flask. HCl in EtOH was added (1.2 mmol) and the solution
stirred for 10 minutes before NaBH4 (2 mmol) was added in portions. The
solution was stirred for 2 hours after which the solvent was removed under
vacuum. Water (20 mL) was added to the crude and the pH brought up to 6-7 by
adding AcOH dropwise. The product (H2L
510) was extracted with DCM (2x25
mL), dried over NaSO4 and the solvent removed under vacuum. .
1H NMR (CDCl3) δ: 7.2-7.35 (m, 2H), 7.19 (s, 1H), 7.01 (s, 1H), 6.85-6.95 (m,
4H), 4.32 (s, 4H), 4.26 (br s, 2H), 4.08 (s, 2H), 2.59 (s, 4H), 2.42 (s, 2H), 1.32 (s,
18H), 1.16 (s, 6H). 13C NMR (CDCl3) δ: 154.4, 141.7, 138.0, 129.2, 128.4, 126.9,
125.4, 125.1, 124.9, 122.4, 119.2, 111.3, 59.5, 54.2, 46.5, 35.1, 34.1, 31.7, 24.6.
Example 3: Synthesis of asymmetric ligand H2L
6
The asymmetric ligand H2L
6 was prepared using the following method:
B was formed by reacting 4-tert-butylsalicylaldehyde (15 mmol) with piperazine
(7.5 mmol) and formaldehyde (15 mmol) in glacial acetic acid (25mL) at 120 °C.
The white precipitate was collected and washed with ethanol and diethyl ether.
63
A solution of 2,2-dimethyl-1,3-propanediamine (6.4 mmol) in MeOH (60 mL) was
added dropwise over 6 h to a refluxing solution of B(6.4 mmol) in MeOH (300
mL). After a further 10 h reflux, the solution was cooled to RT and the bright
yellow supernatant decanted from a bright yellow solid. The residue was redissolved
in DCM and co-evaporated with MeOH until a yellow precipitate
formed. The resulting solids were collected by filtration, washed with MeOH,
pentane and dried under high vacuum for 2 h. This gave a yellow powder (5.0
mmol). A solution of this yellow powder in THF/MeOH (3:1) was treated with
solid NaBH4. The resulting white suspension was allowed to stir for 1 h at RT,
then partitioned between NaHCO3 (2M, aq) and DCM. The organic phase was
separated and dried over Na2SO4, then evaporated to dryness to yield H2L
6
.
H2L
6
:
1H NMR (400 MHz, CDCl3) δ 7.14 – 7.05 (m, 2H), 7.05 – 6.96 (m, 2H), 5.37
– 5.27 (s, 4H), 3.89 – 3.81 (s, 4H), 3.70 – 3.63 (s, 4H), 2.67 – 2.62 (s, 4H), 2.55
– 2.49 (s, 2H), 1.35 (s, 18H), 0.99 – 0.90 (s, 6H).
Example 4: Synthesis of asymmetric ligand H2L
7
The asymmetric ligand H2L
7 was prepared using the following method:
C was prepared by reacting 4-tert-butylsalicylaldehyde (129 mmol) with
formaldehyde (193 mmol) in HBr (48% aq, 970 mmol) with a few catalytic drops
of H2SO4 at 70 °C for 16 hours. The solution was cooled, diluted and extracted
with methylene chloride (30 mL), giving C.
64
N,N′-dimethyl-2,2-dimethyl-1,3-propanediamine was prepared by reaction of 2,2-
dimethyl-1,3-propanediamine (166 mmol) with ethyl formate (80 mL) followed by
reduction with LiAlH4 (10g) in diethyl ether (250 mL).
A solution of 3-(bromomethyl)-2-hydroxy-5-tert-butylbenzaldehyde C (48.4 mmol)
in THF (40 mL) was added to a stirred solution of N,N′-dimethyl-2,2-dimethyl-1,3-
propanediamine (22.0 mmol) in THF (20 mL) giving a yellow suspension. A
solution of triethylamine (61.6 mmol) in THF (10 mL) was added dropwise. The
reaction mixture was stirred for 2 h after which time it was partitioned between
EtOAc and water. The organic extracts were combined, and dried over Na2SO4
before evaporation to dryness to yield an orange oil. The crude product was
dissolved in MeOH (50 mL) and treated with a solution of LiOH (88 mmol) in
MeOH (75 mL). After standing overnight the yellow crystalline precipitate was
isolated by filtration, washed with ice cold MeOH and dried under high vacuum
overnight. This gave a yellow microcrystalline solid (27.6 mmol). A solution of
2,2-dimethyl-1,3-propanediamine (3.52 mmol) in EtOH (18 mL) was added
dropwise over 6 h to a suspension of the latter yellow microcrystalline solid (3.49
mmol) and the resulting yellow solution was allowed to stir for a further 8 h. The
solvent was removed completely and the yellow solid residue was suspended in
pentane and collected by filtration, washed with pentane and dried under high
vacuum for 2 h. This gave a yellow powder (2.8 mmol). A suspension of this
yellow powder in dry EtOH was treated with a solution of HCl in diethyl ether
(2M). Next, solid NaBH4 was added in one portion. The resulting white
suspension was allowed to stir for 1 h at RT then partitioned between NaHCO3
(2M, aq) and DCM. The organic phase was separated and dried over Na2SO4
then evaporated to dryness to yield H2L
7
.
H2L
7
:
1H NMR (400 MHz, CDCl3) δ 7.05 – 6.95 (m, 4H), 5.37 – 5.27 (s, 4H), 3.81
– 3.74 (s, 4H), 3.72 – 3.65 (s, 4H), 2.52 – 2.45 (s, 4H), 2.45 – 2.40 (s, 4H), 2.29
– 2.24 (s, 6H), 1.34 – 1.24 (s, 18H), 1.01 – 0.92 (d, J = 5.5 Hz, 6H).
Example 5: Synthesis of asymmetric ligands Li2Limine
8-10 and H2L
9-10
65
The asymmetric ligands Li2Limine
8-10 and H2L
9-10 were prepared using the
following method:
Preparation of Li2Limine
8-10: To a solution of D (56.3 mmol) in EtOH (500 mL) was
added 2,2-dimethyl-1,3-propanediamine (28.2 mmol) and MgSO4 (281.5 mmol).
Reaction mixture was stirred 3 h at RT. After this time, reaction medium was
filtered, filter cake was washed with DCM, and the mother liquor was evaporated
in vacuo to yield a yellow solid. The latter was solubilised in MeOH, and the
reaction medium was cooled to 0°C. NaBH4 (258.0 mmol) was added by portion.
Reaction mixture was allowed to stir overnight at RT. After this time, solvents
were evaporated in vacuo. DCM and water were added, phases were separated,
and the aqueous phase was extracted with DCM. The organic layers were
combined and dried over Na2SO4. Solvents were evaporated in vacuo to yield a
product that was purified by recrystallization (DCM / MeOH, 20.9 mmol). To a
solution of this purified product (17.5 mmol) in THF (200 mL) was added HCl
66
(1M, 400 mL). Reaction mixture was refluxed overnight. After this time, DCM
was added, phases were separated, and the aqueous phase was extracted with
DCM. The organic layers were combined and dried over Na2SO4. Solvents were
evaporated in vacuo to yield a crude product that was purified by recrystallization
(DCM / heptane, 15.9 mmol). The latter product (9 mmol) was next solubilised in
MeOH (150 mL) and LiOH (36 mmol) was added. Reaction mixture was stirred
for 1 h at RT. After this time, a yellow precipitate had formed, was collected by
filtration, and washed with ice-cold MeOH. To a suspension of this yellow
product (1 equiv.) in MeOH was added dropwise and over 6 h a solution of the
appropriate diamine (2,2-dimethyl-1,3-propanediamine, 1,3-propanediamine or
ethylenediamine, 1 equiv.) in MeOH at RT. Reaction mixture was then stirred
overnight at RT. After this time, a yellow precipitate had formed, was collected by
filtration, and washed with ice-cold MeOH. Products were identified as Li2Limine
8-
10
.
Preparation of H2L
9-10: To a suspension of Li2Limine
9-10 (1 equiv.) in MeOH was
added HCl (1.25M in EtOH, 6 equiv.) and NaBH4 (20 equiv.). Reaction mixture
was stirred overnight at RT. After this time, solvents were evaporated in vacuo.
DCM and water were added, phases were separated, and the aqueous phase
was extracted with DCM. The organic layers were combined, washed with brine
and dried over Na2SO4. Solvents were evaporated in vacuo to yield H2L
9-10
.
H2L
9
: 1H NMR (400 MHz, CDCl3) δ 6.96 (d, J = 2.5Hz, 2H), 6.95 (d, J = 2.5Hz,
2H), 3.83 (s, 8H), 2.65 (t, J = 6.5Hz, 4H), 2.51 (s, 4H), 1.78 – 1.73 (m, 2H), 1.25
(s, 18H), 1.01 (s, 6H).
MS (ESI) m/z: 525.4 ([M+H]+
, 100%)
H2L
10:
1H NMR (400 MHz, CDCl3) δ 6.97 (d, J = 2.5Hz, 2H), 6.95 (d, J = 2.5Hz,
2H), 3.82 (s, 4H), 3.80 (s, 4H), 2.84 (s, 4H), 2.52 (s, 4H), 1.26 (s, 18H), 0.97 (s,
6H). MS (ESI) m/z: 511.3 ([M+H]+
, 100%)
Example 6: synthesis of asymmetric ligands H2L
12-13
67
The asymmetric ligands H2L
12-13 were prepared using the following methods:
For the preparation of H2L
11, see example 1.
Preparation of H2L
12: To a solution of H2L
11 (5.4 mmol) in MeOH (100 mL) was
added benzaldehyde (6.5 mmol) and the reaction stirred at RT for 3 h. The white
precipitate formed was isolated by filtration and washed with cold MeOH (3.78
mmol). A solution of this white product (0.78 mmol) in MeOH (10 mL) and DCM
(5 mL) was treated with methyl acrylate (0.94 mmol) and the reaction stirred at
RT for 16 h after which the solvent was removed in vacuo to yield a white
powder (0.74 mmol). To a solution of this white powder (0.14 mmol) in THF (10
mL) was added aq. 1M HCl until pH 3 was obtained (ca. 4 mL) and the reaction
stirred at RT for 3 h. Neutralisation with aq. K2CO3 followed by extraction with
DCM afforded H2L
12 (0.04 mmol).
MS (ES/CI) m/z: 639.4 ([M+H]+
, 100 %)
IR (ʋC=O, cm-1
, neat): 3300, 2955, 2907, 2869, 1741, 1611, 1465, 1395, 1362,
1298, 1216.
68
Preparation of H2L
13: To a solution of H2L
11 (9.0 mmol) in MeOH (125 mL) was
added methyl acrylate (19.0 mmol) and the reaction stirred at RT for 16 h. The
white solid formed was isolated by filtration and washed with cold MeOH.
Recrystallisation from hot EtOH gave H2L
13
.
H2L
13: 1H NMR (400 MHz, CDCl3) δ 7.33 (d, J = 2.5 Hz, 2H), 6.75 (d, J = 2.5 Hz,
2H), 3.75 (s, 6H), 3.42 (br s, 4H), 3.20 (br s, 4H), 2.94 (br s, 4H), 2.69 (t, J = 2.7
Hz, 4H), 2.32 (br s, 4H), 1.42 (s, 18H), 0.88 (s, 12H), 0.24 (br s, 4H).
MS (ES/CI) m/z: 725.3 ([M]+
, 100 %)
IR (cm-1
, neat): 3301, 2955, 2907, 2869, 1741, 1480, 1216, 1100.
Example 7: synthesis of asymmetric ligands H2L
14-15
The ligands H2L
14-15 were prepared by the following method:
2,2-dimethyl-1,3-propanethiol (5 mmol) was added to a stirred and degassed
solution of KOH (20 mmol) in ethanol (50 ml). The mixture was stirred until all
components form a homogeneous solution. Then C (10 mmol) was added as a
solid to the reaction which slowly dissolves to form a bright yellow solution. The
reaction was allowed to stir under nitrogen atmosphere for 20 h. 1M HCl(aq) was
then added until the reaction mixture reached acidicity (pH ≈ 2) and formed a
white suspension. This mixture was extracted with DCM, the organic extracts
combined and concentrated in vacuo to give an oil. This was purified on silica. A
solution of 2,2-dimethyl-1,3-propanediamine (3.4 mmol) in MeOH (100 ml) was
added dropwise to a stirred solution of this purified oil (2.8 mmol) in MeOH (200
69
ml) at RT under air. The reaction was allowed to stir for 20 h at RT, during which
time a yellow precipitate formed. The precipitate was collected by filtration and
washed with cold MeOH, affording a yellow solid. A MeOH solution (50 mL) of
this yellow product (1.9 mmol) was prepared under nitrogen and allowed to stir
at RT. Under a flow of nitrogen, NaBH4 (19.0 mmol) was added portion-wise as a
solid and the mixture allowed to stir for a further 16 h. The resulting colourless
solution was then quenched by the addition of water. The mixture was extracted
with EtOAc, the organic fractions combined, washed with water and saturated
aqueous NaCl solution and all volatiles were removed in vacuo to afford H2L
14
.
H2L
14:
1H NMR (CDCl3, 400.1 MHz): δ 7.16 (m, 2H), 6.89 (m, 2H), 3.93 (m, 2H),
3.71 (m, 6H), 2.56 (s, 4H), 2.50 (s, 4H), 1.26 (s, 18H), 0.98 (d, 12H)
MS (CI) m/z: 587.4 [M+H]+
1,3-propanedithiol (0.56 mL, 5.5 mmol) was dissolved in EtOH (50 mL) in a
fumecupboard. A solution of C (3g, 11.1 mmol) in EtOH (50 mL) was added
dropwise over 15 minutes and the mixture stirred overnight. The solvent was
removed under vacuum and distilled water (50 mL) was added. The product was
extracted with DCM (2x30 mL), dried over NaSO4 and the solvent removed
under vacuum. The product (was purified by column chromatography (95:5
Cyclohexane:EtOAc) to give a light yellow oil (54%) 1H NMR (CDCl3) δ: 11.22 (s,
2H), 9.90 (s, 2H), 7.60 (d, 2H), 7.45 (d, 2H), 3.79 (s, 4H), 2.61 (t, 4H), 1.93 (q,
2H), 1.35 (s, 18H).
70
The half macrocycle (0.484g, 0.99 mmol) was dissolved in MeOH (35 mL). A
solution of 2,2-dimethyl-1,3-propane (0.12 mL, 0.99 mmol) in MeOH (25 mL) was
added dropwise over 30 minutes and the solution stirred overnight. A yellow
precipitate was filtered off and washed with MeOH. 1H NMR (CDCl3) δ: 13.74 (br
s, 2H), 8.34 (s, 2H), 7.37 (s, 2H), 7.17 (s, 2H), 3.83 (s, 4H), 3.48 (s, 4H), 2.64 (t,
4H), 1.98 (m, 2H), 1.31 (s, 18H), 1.08 (s, 6H).
The yellow precipitate (0.25 g, 0.44 mmol) was dissolved in dry MeOH (50 mL)
before NaBH4 (0.2g, 4.4mmol) was added in portions. The solution was stirred
for 2 hours after which the solvent was removed under vacuum. Water (50 mL)
was added to the crude and the pH brought up to 6-7 by adding AcOH dropwise.
The product (H2L
15) was extracted with DCM (2x25 mL), dried over NaSO4 and
the solvent removed under vacuum.
1H NMR (CDCl3) δ: 7.22 (s, 2H), 6.88 (s, 2H), 4.01 (s, 4H), 3.66 (s, 4H), 2.50 (s,
4H), 2.38 (t, 4H), 1.6 (q, 2H), 1.29 (s, 18H), 1.06 (s, 6H). 13C NMR (CDCl3) δ:
153.3, 141.6, 126.6, 125.3, 123.8, 121.0, 57.6, 54.0, 34.7, 34.0, 31.6, 30.3, 29.8,
29.5, 24.5. ESI-MS: 559.3 ([M+H]+
, 100%).
Example 8: Synthesis of [ L1-15M2(X2)] catalysts
The complexes [L1-15M2(X2)] were prepared using the following method:
General procedure: To a suspension of H2L
1-15 (1 equiv.) in MeOH was added
the appropriate metal precursor M(X)2 (2 equiv.; Ni(OAc)2.4H2O, Mg(OAc)2.4H2O
or Zn(OAc)2.2H2O). Reaction mixture was stirred overnight at RT. After this time,
71
solvents were evaporated and excess water/AcOH was removed by azeotrope
with toluene to yield the desired complexes [L1-15M2(X)2].
[L1Ni2(OAc)2]: MS (ES) m/z: 741.3 ([M - OAc]+
, 100 %).
IR (ʋC=O, cm-1
, neat): 1581, 1410.
[L2Ni2(OAc)2]: MS (ES/CI) m/z: 753.2 ([M - OAc]+
, 100 %).
IR (ʋC=O, cm-1
, neat): 1581, 1413.
[L2Zn2(OAc)2]: MS (ES/CI) m/z: 751.2 ([M - 2AcO-
+ HCO2
-
]
+
, 100 %).
IR (ʋC=O, cm-1
, neat): 1603, 1383.
[L3Ni2(OAc)2]: MS (ES/CI) m/z: 767.2 ([M - OAc]+
, 100 %).
IR (ʋC=O, cm-1
, neat): 1581, 1413.
[L3Mg2(OAc)2]: 1H NMR (400 MHz, MeOD) δ 7.02 (m, 4H), 3.74 (d, J = 18.9 Hz,
4H), 3.6 (d, J = 8.9 Hz, 4H), 2.46 (d, J = 8.7 Hz, 4H), 2.44 (m, 2H), 2.41 (d, J =
8.7 Hz, 2H), 1.90 (s, 6H), 1.54 (m, 2H), 1.30 (s, 9H), 1.28 (s, 9H), 0.96 (s, 6H),
0.95 (s, 6H), 0.84 (t, J = 7.3 Hz, 3H).
MS (ES/CI) m/z: 685.3 ([M - 2OAc]+
, 100 %).
IR (ʋC=O, cm-1
, neat): 1607, 1395.
[L4Ni2(OAc)2]: MS (ES/CI) m/z: 781.2 ([M - OAc]+
, 100 %).
IR (ʋC=O, cm-1
, neat): 1581, 1413.
[L7Ni2(OAc)2]: MS (ES/CI) m/z: 739.2 ([M - 2OAc + O2CH]+
, 100 %).
IR (ʋC=O, cm-1
, neat): 1581, 1414.
[L9Mg2(OAc)2]: 1H NMR (400 MHz, CD3OD) δ 7.01 (s, 4H), 4.00 (d, J = 3.6Hz,
2H), 3.97 (d, J = 3.7Hz, 2H), 3.27 (d, J = 12.0Hz, 2H), 3.21 (d, J = 12.0Hz, 2H),
3.05 – 2.99 (m, 2H), 2.79 – 2.70 (m, 4H), 2.64 (d, J = 11.6Hz, 2H), 1.94 – 1.76
(m, br, 4H), 1.25 (s, 18H), 1.23 (s, 3H), 1.01 (s, 3H).
MS (ESI) m/z: 615.3 ([M - 2AcO-
+ HCO2
-
]
+
, 100%).
[L9Ni2(OAc)2]: MS (ESI) m/z: 683.2 ([M - 2AcO-
+ HCO2
-
]
+
, 100%). IR (ʋC=O, cm-1
,
neat): 1566, 1477.
72
[L9Ni2(OAc)2]: MS (ESI) m/z: 683.2 ([M - 2AcO-
+ HCO2
-
]
+
, 100%). IR (ʋC=O, cm-1
,
neat): 1566, 1477.
[L10Ni2(OAc)2]: MS (ESI) m/z: 669.1 ([M- 2OAc + O2CH]+
, 100%). IR (ʋC=O, cm-1
,
neat): 1566, 1477.
[L13Ni2(OAc)2]: MS (ES/CI) m/z: 855.2 ([M - 2AcO-
- 2CH3 + HCO2
-
]
+
, 100 %),
809.2 ([M - 2AcO-
- 2CH3 + 1HCO2
-
]
+
, 80 %).
IR (ʋC=O, cm-1
, neat): 1573, 1480.
[L14Ni2(OAc)2]: IR (ʋC=O, cm-1
, neat): 1566 and 1413.
[L15Ni2(OAc)2]: MS (CI) m/z: 717 ([M - 2AcO-
+ HCO2
-
]
+
, 100%).
IR (ʋC=O, cm-1
, neat): 1562 and 1410.
Example 9: Synthesis of [Limine
8Mg2(OAc)2] complex
The complex [Limine
8Mg2(OAc)2] was prepared using the following method:
Preparation of [Limine
8Mg2(OAc)2]: To a suspension of Li2Limine
8
(1 equiv.) in
MeOH was added Mg(OAc)2.4H2O (2 equiv.). Reaction mixture was stirred
overnight at RT. After this time, solvents were evaporated. Pentane was added
and the reaction mixture was filtered. Filtrate was evaporated to yield complex
[Limine
8Mg2(OAc)2] as a slightly yellow solid.
73
Limine
8Mg2(OAc)2: 1H NMR (400 MHz, CD3OD) δ 8.13 (d, J = 2.0Hz, 2H), 7.31 (d,
J = 2.7Hz, 2H), 7.26 (d, J = 2.7Hz, 2H), 4.09 – 4.03 (m, 4H), 3.31 – 3.26 (m, 2H),
2.86 – 2.79 (m, 2H), 2.66 (d, J = 11.3Hz, 2H), 2.22 – 2.14 (m, 2H), 1.90 – 1.40
(s, br, 6H), 1.31 (s, 18H), 1.21 (s, 3H), 1.16 (s, 3H), 1.14 (s, 3H), 1.02 (s, 3H).
MS (ESI) m/z: 639.3 ([M - 2AcO-
+ HCO2
-
]
+
, 100%).
Example 10: Polymerisation of CO2 and CHO at 100°C and 0.01 mmol of
[LM2(OAc)2].
[LM2(OAc)2] (0.01 or 0.025mmol) was dissolved in cyclohexene oxide (25 or 50
mmol) in a Schlenk. The vessel was degassed, charged with CO2 (1 bar) and
heated at 100 °C with magnetic stirring for the right time, giving
poly(cyclohexene carbonate). The polymer contained >99% carbonate linkages
and was produced with >99% selectivity in all cases. The asymmetric ligands L1-
L4 having N-substitution demonstrate superior activity, productivity (turnover
number) and activity under low loadings. All the asymmetric complexes
demonstrate excellent selectivity for polymer, activity under low pressures and
narrow polydispersity polymers. The results are shown in Table 1.
Catalyst cat:CH
O
Vol
CHO
(mL)
T
(°C)
P
(bar)
Time
(h)
Conversion
(PCHC+Cy
clic vs CHO
Selectivit
y
TON TOF PDI Mn
[L1Ni2(OAc)2] 1:5000 5 100 1 3 44% 100% 2203 734 1.254 12600
[L1Ni2(OAc)2] 1:1000 2.5 100 1 1.17 51.8 99.9% 518 443 1.018/
1.051
16300
/ 9200
[L2Ni2(OAc)2] 1:5000 5 100 1 3 44% 100% 2212 737 1.29 13100
[L3Ni2(OAc)2] 1:5000 5 100 1 3 47% 100% 2370 790 1.234 12900
[L4Ni2(OAc)2] 1:5000 5 100 1 3 48% 100% 2381 794 1.241 12900
[Limine
8Mg2(O
Ac)2]
1:1000 2.5 100 1 4 32.55% 100% 326 81
[L9Ni2(OAc)2] 1:1000 2.5 100 1 3 27.9% 99.5% 279 93 1.042/
1.095
12700
/ 5300
[L9Mg2(OAc)
2]
1:1000 2.5 100 1 3 43.23% 100% 432 144 1.035/
1.196
20400
/ 6600
Table 1: Copolymerisation of CHO and CO2 using [LM2(OAc)2]
75
Example 11: Polymerisation of CO2 and CHO at 130°C and high pressure with [LM2(OAc)2].
[LXM2(OAc)2] (0.0148 mmol) was added to a dried Schlenk tube and dried under vacuum for 60 minutes. CHO (15 mL, 148.26 mmol) was
added under N2 via a syringe, the mixture was transferred to a reactor under pressure 0.2 bar CO2. Reactor vessel was heated to 130 °C,
then pressured to 10 bar and stirred for 1-2 hours, after which the vessel was cooled to 5°C, the pressure slowly released and a sample
taken for GPC/NMR analysis. The results are shown in Table 2.
Catalyst cat:CH
O
Vol
CHO
(mL)
T
(°C)
P
(bar)
Time
(h)
Conversion
(PCHC+Cy
clic vs CHO
Selectivit
y
TON TOF PDI Mn
[L11Mg2(OAc
)2]
1:1000
0
15 130 10 2 44.2% 100% 4420 2210 1.192 15100
[L11Ni2(OAc)2
]
1:1000
0
15 130 10 2 51.6% 98.5% 5156 2578 1.264 29400
[L1Ni2(OAc)2] 1:1000
0
15 130 10 1 44.5% 99.8% 4450 4450 1.234 21300
Table 2: Comparison of catalytic activity of equivalent Ni and Mg complexes under identical conditions for CHO and CO2 (10 bar)
copolymerisation at 1:10,000 loading.
Although the symmetrical magnesium catalyst [L
11Mg2(OAc)2] and nickel catalyst
[L11Ni2(OAc)2] perform well and have high selectivity and activity (TOF) the
asymmetric catalyst [L1Ni2(OAc)2] has a far superior activity and produces the
5 same turn-over-number in half the time. This clearly demonstrates the unexpected
benefits that an asymmetric catalyst can give over a symmetric catalyst.Example 12:
Polymerisation of CO2 and PO with [LM2(OAc)2].
[LXM2(OAc)2] (0.0043 - 0.21 mmol) was dissolved in propylene oxide (211 mmol) in
a Schlenk tube and the solution transferred into a pre-dried 100 mL stainless steel
10 Parr pressure vessel using a syringe. The vessel was charged with CO2 (20 bar)
and heated to the desired temperature °C. The solution was stirred mechanically for
the desired time, giving poly(propylene carbonate) as a white solid with a high
selectivity for polymer and >99% carbonate linkages. The catalysts showed
excellent activity, producing a high yield of polymer. The catalysts demonstrated
15 significantly improved selectivity and activity when compared to symmetric catalyst
[L11Ni2(OAc)2] and could be used at a much lower catalyst loading. The results are
shown in
20
25
77
Table 3.
Catalyst cat:PO T
(°C
)
P
(bar
)
Tim
e
(h)
Selectivit
y for
polymer
Polyme
r yield
PDI Mn
[L1Ni2(OAc)2] 1:5000 80 20 9 85% 6.8g 1.02
7 /
1.03
2
3400
0 /
1690
0
[L2Ni2(OAc)2] 1:5000 80 20 9 89% 8g 1.02
7 /
1.03
0
4260
0 /
2120
0
[L3Ni2(OAc)2] 1:5000 80 20 9 87% 7.8g 1.02
5 /
1.02
8
3890
0 /
1930
0
[L1Ni2(OAc)2] 1:1000 70 20 16 87% 19g 1.03
4 /
1.03
0
4450
0 /
2230
0
[L1Ni2(OAc)2] 1:5000
0
90 20 16 80% 2.2g
1.1
1970
0
[L7Ni2(OAc)2] 1:1000 80 20 1 90% 8.5g
1.02/
1.03
1700
0
/8600
[L11Ni2(OAc)2
]
1:1000 80 20 16 75% 10.4g 1.12 1520
0
Table 3: Copolymerisation of PO and CO2 using [LM2(OAc)2]
78
Example 13: Polymerisation of CO2 and PO with [L1Ni2(OAc)2] in the presence of a
starter – PPG-425
[L1Ni2(OAc)2] (0.21 mmol) and PPG-425(4.3mmol) was dissolved in propylene
5 oxide (211 mmol) in a Schlenk tube and the solution transferred into a pre-dried 100
mL stainless steel Parr pressure vessel using a syringe. The vessel was charged
with CO2 (20 bar) and heated to the 80 °C. The solution was stirred mechanically for
the 6 hrs, giving a poly(propylenecarbonate) diol (9.2g) as a clear viscous oil with a
high selectivity for polymer and >99% carbonate linkages.
10
Example 14: Polymerisation of CO2 and PO with [L1Ni2(OAc)2] in the presence of a
starter – 1,6-hexanediol
[L1Ni2(OAc)2] (0.21 mmol) and 1,6-hexanediol (8.4mmol) was dissolved in
propylene oxide (211 mmol) in a Schlenk tube and the solution transferred into a
15 pre-dried 100 mL stainless steel Parr pressure vessel using a syringe. The vessel
was charged with CO2 (20 bar) and heated to the 80 °C. The solution was stirred
mechanically for 12 hrs, giving a poly(propylenecarbonate) diol (6.4g) as a clear
viscous oil with a high selectivity for polymer and >99% carbonate linkages.
Example 15: Polymerisation of CO2 and PO with [L1Ni2(OAc)2] in the presence of a
20 solvent – toluene
[L1Ni2(OAc)2] (0.021 mmol) was dissolved in propylene oxide (106 mmol) in a
Schlenk tube and a further 7.5mL of dry toluene was added and the solution
transferred into a pre-dried 100 mL stainless steel Parr pressure vessel using a
syringe. The vessel was charged with CO2 (20 bar) and heated to the 80 °C. The
25 solution was stirred mechanically for the 16 hrs, giving a toluene solution of
poly(propylenecarbonate) which was isolated (5g) as a white powder with a high
selectivity for polymer and >99% carbonate linkages.
79
Example 16: Polymerisation of CO2 and PO with [L1Ni2(OAc)2] in the presence of a
solvent – n-butyl acetate
[L1Ni2(OAc)2] (0.021 mmol) was dissolved in propylene oxide (106 mmol) in a
Schlenk tube and a further 7.5mL of dry n-butyl acetate was added and the solution
5 transferred into a pre-dried 100 mL stainless steel Parr pressure vessel using a
syringe. The vessel was charged with CO2 (20 bar) and heated to the 80 °C. The
solution was stirred mechanically for 16 hrs, giving an n-butyl acetate solution of
poly(propylenecarbonate) which was isolated (4.7g) as a white powder with a high
selectivity for polymer and >99% carbonate linkages.
Example 17: Polymerisation of CO2 and tert-butyl glycidyl ether with [L1
10 Ni2(OAc)2]
[L1Ni2(OAc)2] (0.105 mmol) was dissolved in tert-butyl glycidyl ether (105 mmol) in a
Schlenk tube and the solution transferred into a pre-dried 100 mL stainless steel
Parr pressure vessel using a syringe. The vessel was charged with CO2 (20 bar)
and heated to the 80 °C. The solution was stirred mechanically for 16 hrs, giving
15 poly(tert-butylether 1,2-glycerol carbonate) which was isolated (8.6g) as a white
powder with a high selectivity for polym for polymer and >99% carbonate linkages.
.
All of the features disclosed in this specification (including any accompanying
20 claims, abstract and drawings), and/or all of the steps of any method or process so
disclosed, may be combined in any combination, except combinations where at
least some of such features and/or steps are mutually exclusive.
Each feature disclosed in this specification (including any accompanying claims,
abstract and drawings) may be replaced by alternative features serving the same,
25 equivalent or similar purpose, unless expressly stated otherwise. Thus, unless
expressly stated otherwise, each feature disclosed is one example only of a generic
series of equivalent or similar features.
80
The invention is not restricted to the details of the foregoing embodiment(s). The
invention extends to any novel one, or any novel combination, of the features
disclosed in this specification (including any accompanying claims, abstract and
drawings), or to any novel one, or any novel combination, of the steps of any
5 method or process so disclosed
10
15
20
25
81
WE CLAIM:
1. A catalyst of formula (I):
(I)
wherein:
5 M1 and M2 are independently selected from Zn(II), Cr(II), Co(II), Cu(II), Mn(II), Ni(II),
Mg(II), Fe(II), Ti(II), V(II), Cr(III)-X, Co(III)-X, Ni(III)-X, Mn(III)-X, Fe(III)-X, Ca(II),
Ge(II), Al(III)-X, Ti(III)-X, V(III)-X, Ge(IV)-(X)2 or Ti(IV)-(X)2;
R1 and R2 are independently selected from hydrogen, halide, a nitro group, a nitrile
group, an imine, an amine, an ether group, a silyl group, a silyl ether group, a
10 sulfoxide group, a sulfonyl group, a sulfinate group or an acetylide group or an
optionally substituted alkyl, alkenyl, alkynyl, haloalkyl, aryl, heteroaryl, alkoxy,
aryloxy, alkylthio, arylthio, alicyclic or heteroalicyclic group;
R3A and R3B are independently selected from optionally substituted alkylene,
alkenylene, alkynylene, heteroalkylene, heteroalkenylene, heteroalkynylene,
15 arylene, heteroarylene or cycloalkylene, wherein alkylene, alkenylene, alkynylene,
heteroalkylene, heteroalkenylene and heteroalkynylene, may optionally be
interrupted by aryl, heteroaryl, alicyclic or heteroalicyclic;
82
R5 is independently selected from H, or optionally substituted aliphatic,
heteroaliphatic, alicyclic, heteroalicyclic, aryl, heteroaryl, alkylheteroaryl or alkylaryl;
E1 is C, E2 is O, S or NH or E1 is N and E2 is O;
E3, E4, E5 and E6 are each independently selected from N, NR4, O and S, wherein
5 when any of E3, E4, E5 or E6 are N, is , and wherein when any of E3,
E4, E5 or E6 are NR4, O or S, is ; R4 is independently selected from H,
or optionally substituted aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl,
heteroaryl, alkylheteroaryl or alkylaryl;
X is independently selected from OC(O)Rx
, OSO2R
x
, OSORx
, OSO(Rx
)2, S(O)Rx
,
ORx
10 , phosphinate, halide, nitrate, hydroxyl, carbonate, amino, amido or optionally
substituted aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl or heteroaryl;
Rx is independently hydrogen, or optionally substituted aliphatic, haloaliphatic,
heteroaliphatic, alicyclic, heteroalicyclic, aryl, alkylaryl or heteroaryl; and
G is absent or independently selected from a neutral or anionic donor ligand which
15 is a Lewis base;
and wherein:
i) R3A is different from R3B; and/or
ii) At least one occurrence of E3, E4, E5 and E6 is different to a remaining
occurrence of E3, E4, E5 and E6.
20 2. The catalyst of claim 1, wherein R3A is different from R3B, and each occurrence
of E3, E4, E5 and E6 is the same.
3. The catalyst of claim 1, wherein R3A is the same as R3B and at least one
occurrence of E3, E4, E5 and E6 is different to a remaining occurrence of E3, E4,
E5 and E6.
83
4. The catalyst of claim 1 or 2, wherein R3A is different from R3B and at least one
occurrence of E3, E4, E5 and E6 is different to a remaining occurrence of E3, E4,
E5 and E6.
5. The catalyst of any of claims 1, 3 or 4, wherein E3 and E5 are the same, and E4
5 and E6 are the same, and wherein E3 and E5 are different from E4 and E6,
preferably wherein E3 and E5 are S or O, and E4 and E6 are N or NR4, wherein
R4 is preferably H or optionally substituted alkyl.
6. The catalyst of any of claims 1, 3 or 4, wherein E3 and E4 are the same, and E5
and E6 are the same, and wherein E3 and E4 are different from E5 and E6.
10 7. The catalyst of any preceding claim, wherein R3A or R3B is selected from
substituted or unsubstituted alkylene, substituted or unsubstituted cycloalkylene
or optionally substituted arylene, preferably substituted or unsubstituted
propylene, substituted or unsubstituted cyclohexylene or substituted or
unsubstituted phenylene or biphenylene, even more preferably ethylene,
15 propylene, 2,2-dialkylpropylene such as 2,2-dimethylpropylene. 2,2-
difluoropropylene, cyclohexylene or phenylene, even more preferably 2,2-
dimethylpropylene.
8. The catalyst of any of claims 1, 2, 4, 5 or 6, wherein R3A is different from R3B, R3A
is substituted or unsubstituted alkylene, preferably substituted or unsubstituted
20 propylene, even more preferably propylene, 2,2-difluoropropylene or 2,2-
dimethylpropylene or optionally substituted cycloalkylene preferably
cyclohexylene, and R3B is substituted or unsubstituted arylene preferably
substituted or unsubstituted cyclohexylene, phenylene or biphenylene, or
optionally substituted alkylene, preferably optionally substituted propylene, even
25 more preferably 2,2-dialkylpropylene such as 2,2-dimethylpropylene., 2,2-
fluoropropylene, ethylene or propylene.
9. The catalyst of any of claims 1, 2, 4, 5, 6 or 8, wherein R3A is different from R3B
and wherein R3A is 2,2-dimethylpropylene and R3B is phenylene, or R3A is a
84
disubstituted cycloalkylene which acts as a bridging group between two
nitrogen centres in the catalyst of formula (I) and R3B is 2,2-dimethylpropylene,
or R3A is 2,2-dimethylpropylene and R3B is propylene or ethylene, or R3A is
propylene, and R3B is 2,2-dimethylpropylene.
5
10. The catalyst of any of claims 1, 3, 4, 5, 6, or 7, wherein each E3, E4, E5 and E6
is NR4, and one of the R4 groups is different, preferably E4 is different, preferably
one of the R4 groups is selected from an optionally substituted alkyl or
heteroalkyl, more preferably one of the R4 groups is selected from methyl, ethyl,
10 propyl, butyl or –alkyl- C(O)-OR19 such as methyl propanoate, preferably the
remaining R4 groups are hydrogen.
11. The catalyst of any of claims 1, 3, 4, 5, 6, or 7, wherein each E3, E4, E5 and E6
is NR4, and two of the R4 groups are different, such as E3 and E5, E3 and E4, E4
15 and E6, E4 and E5, E5 and E6, and/or E3 and E6, preferably E3 and E6 or E3 and
E5 are different, preferably two of the R4 groups are selected from an optionally
substituted alkyl or heteroalkyl, more preferably two of the R4 groups are
selected from methyl, ethyl, propyl, butyl or –alkyl-C(O)-OR19 such as methyl
propanoate, preferably the remaining R4 groups are hydrogen.
20
12. The catalyst of any of claims 1, 3, 4, 5, 6, or 7, wherein two of E3, E4, E5 and E6
are NR4, and two of E3, E4, E5 and E6 are N, preferably two of E3, E4, E5 and E6
are NH and two of E3, E4, E5 and E6 are N, more preferably, E4 and E6 are NH
and E3 and E5 are N, or E3 and E5 are NH and E4 and E6 are N.
25
13. The catalyst of any of claims 1, 3, 4, 5, 6, or 7, wherein two of E3, E4, E5 and E6
are S, and two of E3, E4, E5 and E6 are NR4, preferably two of E3, E4, E5 and E6
are S, and two of E3, E4, E5 and E6 are NH, more preferably E3 and E5 are S,
and , E4 and E6 are NH.
30
85
14. The catalyst of any preceding claim, wherein each occurrence of R2 and R5 are
H, E1 is C and E2 is O, S or NH, preferably E2 is O.
15. The catalyst of any preceding claim wherein M1 or M2 is selected from Mg(II),
5 Ni(II), Ni(III)-X, Co(II), Co(III)-Xand Zn(II).
16. The catalyst of any preceding claim wherein M1 or M2 is selected from Ni(II) or
Mg(II).
10 17. The catalyst of any preceding claim wherein M1 and M2 are the same,
preferably wherein M1 and M2 are Mg(II), Ni(II), Ni(III)-X, Co(II), Co(III)-X or
Zn(II).
18. The catalyst of any preceding claim wherein M1 and M2 are the same and are
15 Ni(II) or Mg(II).
19. The catalyst of any of claims 1, 3, 4, 5, 6, 7, 10, 14, 15, 16, 17 or 18 wherein M1
and M2 are the same and are Ni(II), and each E3, E4, E5 and E6 is NR4, wherein
at least one of the R4 groups is different from a remaining occurrence of R4 and
20 is selected from an optionally substituted alkyl or heteroalkyl and preferably the
remaining R4 group/s are hydrogen.
20. The catalyst according to any preceding claim, wherein R1 is independently
selected from hydrogen, halide, amino, nitro, sulfoxide, sulfonyl, sulfinate, and
25 optionally substituted alkyl, alkenyl, aryl, heteroaryl, alkoxy or alkylthio,
preferably R1 is an optionally substituted alkyl, more preferably R1 is tertiary
butyl.
86
21. The catalyst of any preceding claim, wherein each occurrence of R1 is the
same.
22. The catalyst according to any preceding claim, wherein X is independently
OC(O)Rx
, OSO2R
x
, OS(O)Rx
, OSO(Rx
)2, S(O)Rx
, ORx
5 , halide, nitrate, hydroxyl,
carbonate, amino, nitro, amido, and optionally substituted alkyl, heteroalkyl, aryl
or heteroaryl, preferably X is OC(O)Rx
, more preferably X is acetate
23. The catalyst according to any preceding claim, wherein Rx
is independently
10 optionally substituted alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl or
alkylaryl.
24. The catalyst of claim 1, wherein both occurrences of R1 are the same, and are
selected from hydrogen, halide, amino, nitro, sulfoxide, sulfonyl, sulfinate, silyl,
15 silyl ether and an optionally substituted alkyl, alkenyl, aryl, heteroaryl, alkoxy,
aryloxy or alkylthio; R2 is hydrogen; R3A and R3B are the same or different, and
are selected from substituted or unsubstituted alkylene, substituted or
unsubstituted cycloalkylene and substituted or unsubstituted arylene; E3 to E6
are the same or different and are selected from NR4, S, N or O; R4 is hydrogen,
20 an optionally substituted alkyl or heteroalkyl; each X is the same, and is
selected from OC(O)Rx
, ORx
, halide, carbonate, amino, nitro, alkyl, aryl,
heteroaryl, phosphinate or OSO2R
x
, Rx
is alkyl, alkenyl, alkynyl, heteroalkyl,
aryl, heteroaryl or alkylaryl; Rx is alkyl, alkenyl, alkynyl, heteroalkyl, aryl,
heteroaryl or alkylaryl; each G (where present) is independently selected from
25 halide; water; a heteroaryl optionally substituted by alkyl, alkenyl, alkynyl,
alkoxy, halogen, hydroxyl, nitro or nitrile; M1 and M2 are independently selected
from Mg(II), Zn(II), Ni(II), Ni(III)-X, Cr(II), Cr(III)-X, Co(II), Co(III)-X Mn(II), Fe(II),
and Fe(III)-X, preferably M1 and M2 are independently selected from Mg(II),
87
Ni(II), Ni(III)-X, Co(II), Co(III)-X and Zn(II), preferably M1 and M2 are the same,
and are selected from Ni(II) or Mg(II).
25. The catalyst of claim 1, wherein both occurrences of R1 are the same, and are
5 selected from hydrogen, halide, amino, nitro, sulfoxide, sulfonyl, sulfinate, silyl,
silyl ether and an optionally substituted alkyl, alkenyl, aryl, heteroaryl, alkoxy,
aryloxy or alkylthio; R2 is hydrogen; R3A is a substituted or unsubstituted
cycloalkylene or alkylene and R3B is a substituted or unsubstituted alkylene, or
arylene; each occurrence of E3 to E6 is NR4; R4 is hydrogen; each X is the
same, and is selected from OC(O)Rx
, ORx
10 , halide, carbonate, amino, nitro,
alkyl, aryl, heteroaryl, phosphinate or OSO2R
x
, Rx
is alkyl, alkenyl, alkynyl,
heteroalkyl, aryl, heteroaryl or alkylaryl; Rx
is alkyl, alkenyl, alkynyl, heteroalkyl,
aryl, heteroaryl or alkylaryl; each G (where present) is independently selected
from halide; water; a heteroaryl optionally substituted by alkyl, alkenyl, alkynyl,
15 alkoxy, halogen, hydroxyl, nitro or nitrile; M1 and M2 are independently selected
from Mg(II), Zn(II), Ni(II), Ni(III)-X, Cr(II), Cr(III)-X, Co(II), Co(III)-X, Mn(II), Fe(II),
and Fe(III)-X, preferably M1 and M2 are independently selected from Mg(II),
Ni(II), Ni(III)-X, Co(II), Co(III)-X and Zn(II), preferably M1 and M2 are the same,
and are selected from Ni(II) or Mg(II).
20
26. The catalyst of claim 1, wherein both occurrences of R1 are the same, and are
selected from hydrogen, halide, amino, nitro, sulfoxide, sulfonyl, sulfinate, silyl,
silyl ether and an optionally substituted alkyl, alkenyl, aryl, heteroaryl, alkoxy,
aryloxy or alkylthio; R2 is hydrogen; R3A and R3B are the same and are
25 substituted or unsubstituted alkylene; each of E3, E4, E5 and E6 is NR4 wherein
one of the R4 groups is different and selected from an optionally substituted
alkyl or heteroalkyl and the remaining R4 groups are hydrogen; each X is the
same, and is selected from OC(O)Rx
, ORx
, halide, carbonate, amino, nitro,
alkyl, aryl, heteroaryl, phosphinate or OSO2R
x
, Rx
is alkyl, alkenyl, alkynyl,
heteroalkyl, aryl, heteroaryl or alkylaryl; Rx
30 is alkyl, alkenyl, alkynyl, heteroalkyl,
88
aryl, heteroaryl or alkylaryl; each G (where present) is independently selected
from halide; water; a heteroaryl optionally substituted by alkyl, alkenyl, alkynyl,
alkoxy, halogen, hydroxyl, nitro or nitrile; M1 and M2 are independently selected
from Mg(II), Zn(II), Cr(II), Cr(III)-X, Co(II), Co(III)-X, Mn(II), Ni(II), Ni(III)-X, Fe(II),
5 and Fe(III)-X, preferably M1 and M2 are independently selected from Mg(II),
Ni(II), Ni(III)-X, Co(II) and Co(III)-X and Zn(II), preferably M1 and M2 are the
same, and are selected from Ni(II) or Mg(II).
27. The catalyst of claim 1, wherein both occurrences of R1 are the same, and are
10 selected from hydrogen, halide, amino, nitro, sulfoxide, sulfonyl, sulfinate, silyl,
silyl ether and an optionally substituted alkyl, alkenyl, aryl, heteroaryl, alkoxy,
aryloxy or alkylthio; R2 is hydrogen; R3A and R3B are selected from substituted or
unsubstituted alkylene, substituted or unsubstituted cycloalkylene and
substituted or unsubstituted arylene; E3 to E6 are selected from N, NR4, S or O;
15 R4 is selected from hydrogen, or optionally substituted alkyl or heteroalkyl; each
X is the same, and is selected from OC(O)Rx
, ORx
, or OSO2R
x
, Rx
is alkyl,
alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl or alkylaryl; each G (where
present) is independently selected from halide; water; a heteroaryl optionally
substituted by alkyl, alkenyl, alkynyl, alkoxy, halogen, hydroxyl, nitro or nitrile;
20 M1 and M2 are independently selected from Mg(II), Zn(II), Cr(II), Cr(III)-X, Co(II),
Co(III)-X, Mn(II), Ni(II), Ni(III)-X, Fe(II), and Fe(III)-X, preferably M1 and M2 are
independently selected from Mg(II), Ni(II), Ni(III)-X, Co(II), Co(III)-X and Zn(II),
preferably M1 and M2 are the same, and are selected from Ni(II) or Mg(II); and
wherein:
25 (i) R3A is different from R3B; and/or
(ii) at least one occurrence of E3, E4, E5 and E6 is different to a remaining
occurrence of E3, E4, E5 and E6.
89
28. The catalyst of claim 1, wherein both occurrences of R1 are the same, and are
selected from an optionally substituted alkyl; R2 is hydrogen; R3A and R3B are
selected from substituted or unsubstituted alkylene, substituted or
unsubstituted cycloalkylene, and substituted or unsubstituted arylene; each
5 occurrence of E3 to E6 is NR4; R4 is selected from hydrogen, or optionally
substituted alkyl or heteroalkyl; each X is the same, and is selected from
OC(O)Rx
, ORx
, or OSO2R
x
, Rx
is alkyl, alkenyl, alkynyl, heteroalkyl, aryl,
heteroaryl or alkylaryl; M1 and M2 are independently selected from Mg(II), Ni(II),
Ni(III)-X Co(II), Co(III)-X and Zn(II). Preferably M1 and M2 are the same, and are
10 selected from Ni(II) or Mg(II); and wherein:
(i) R3A is different from R3B; and/or
(ii) at least one occurrence of E3, E4, E5 and E6 is different to a remaining
occurrence of E3, E4, E5 and E6.
15 29. The catalyst of claim 1, wherein both occurrences of R1 are the same, and are
tertiary butyl; R2 is hydrogen; R3A and R3B are selected from tertiary butylene,
benzylene, ethylene, propylene, 2,2-dimethylpropylene; each occurrence of E3
to E6 is NR4; R4 is selected from hydrogen, methyl, ethyl, propyl, butyl, or –alkylC(O)-OR19
such as methyl propanoate ; each X is the same, and is OAc; M1 and
20 M2 are independently selected from Mg(II), Ni(II), Co(II), Co(III)-X, Ni(III)-X and
Zn(II), preferably M1 and M2 are the same, and are selected from Ni(II) or
Mg(II); and wherein:
iii) R3A is different from R3B; and/or
iv) at least one occurrence of E3, E4, E5 and E6 is different to a remaining
25 occurrence of E3, E4, E5 and E6.
90
30. The catalyst of claim 1, of the formula:
, , ,
91
92
93
5 31. The catalyst of claim 1 of the formula:
94
, ,
95
32. A ligand of formula (II):
5 (II)
wherein:
R1 and R2 are independently selected from hydrogen, halide, a nitro group, a nitrile
group, an imine, an amine, an ether group, a silyl group, a silyl ether group, a
sulfoxide group, a sulfonyl group, a sulfinate group or an acetylide group or an
96
optionally substituted alkyl, alkenyl, alkynyl, haloalkyl, aryl, heteroaryl, alkoxy,
aryloxy, alkylthio, arylthio, alicyclic or heteroalicyclic group;
R3A and R3B are independently selected from optionally substituted alkylene,
alkenylene, alkynylene, heteroalkylene, heteroalkenylene, heteroalkynylene,
5 arylene, heteroarylene or cycloalkylene, wherein alkylene, alkenylene, alkynylene,
heteroalkylene, heteroalkenylene and heteroalkynylene, may optionally be
interrupted by aryl, heteroaryl, alicyclic or heteroalicyclic;
R5 is independently selected from H, or optionally substituted aliphatic,
heteroaliphatic, alicyclic, heteroalicyclic, aryl, heteroaryl, alkylheteroaryl or alkylaryl;
10 E1 is C, E2 is OY, S or NH or E1 is N and E2 is OY;
Y is hydrogen or an alkali metal;
E3, E4, E5 and E6 are each independently selected from N, NR4, O and S, wherein
when any of E3, E4, E5 or E6 are N, is , and wherein when any of E3,
E4, E5 or E6 are NR4, O or S, is ; R4 is independently selected from H,
15 or optionally substituted aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl,
heteroaryl, alkylheteroaryl or alkylaryl;
and wherein:
(i) R3A is different from R3B; and/or
20 (ii) at least one occurrence of E3, E4, E5 and E6 is different to a
remaining occurrence of E3, E4, E5 and E6.
33. The ligand of claim 32, wherein the groups R1, R2, R3A, R3B, R4, R5, E1, E2, E3,
E4, E5, and E6 are as defined in any of claims 2-23.
25
34. The ligand of claim 32, wherein both occurrences of R1 are the same, and are
selected from hydrogen, halide, amino, nitro, sulfoxide, sulfonyl, sulfinate, silyl,
silyl ether and an optionally substituted alkyl, alkenyl, aryl, heteroaryl, alkoxy,
aryloxy or alkylthio; R2 is hydrogen; R3A and R3B are selected from substituted or
30 unsubstituted alkylene, substituted or unsubstituted cycloalkylene and
97
substituted or unsubstituted arylene; E3 to E6 are N, NR4, S or O; R4 is selected
from hydrogen, or optionally substituted alkyl or heteroalkyl;
and wherein:
i) R3A is different from R3B; and/or
5 ii) at least one occurrence of E3, E4, E5 and E6 is different to a remaining
occurrence of E3, E4, E5 and E6.
35. The ligand of claim 32 wherein both occurrences of R1 are the same, and are
selected from an optionally substituted alkyl; R2 is hydrogen; R3A and R3B are
10 selected from substituted or unsubstituted alkylene, substituted or
unsubstituted cycloalkylene, and substituted or unsubstituted arylene; each
occurrence of E3 to E6 is NR4; R4 is selected from hydrogen, or optionally
substituted alkyl or heteroalkyl;
and wherein:
15 iii) R3A is different from R3B; and/or
iv) at least one occurrence of E3, E4, E5 and E6 is different to a remaining
occurrence of E3, E4, E5 and E6.
36. The ligand of claim 32, wherein both occurrences of R1 are the same, and are
20 tertiary butyl; R2 is hydrogen; R3A and R3B are selected from butylene,
benzylene, ethylene, propylene, 2,2-dimethylpropylene; each occurrence of E3
to E6 is NR4; R4 is selected from hydrogen, methyl, ethyl, propyl, butyl, or–alkylC(O)-OR19
such as methyl propanoate ;
and wherein:
25 i) R3A is different from R3B; and/or
ii) at least one occurrence of E3, E4, E5 and E6 is different to a remaining
occurrence of E3, E4, E5 and E6.
37. The ligand of claim 32 of the formula:
98
(IIa)
Wherein:
R1 is tertiary butyl; R2 is hydrogen; R3 is 2,2-dimethylpropylene; and R4 is selected
from methyl, ethyl, propyl, or butyl;
5 or:
(IIb)
or:
(IIc)
or:
99
(IId)
or:
(IIe)
5 wherein:
R3 is selected from 2,2-dimethylpropylene, propylene, or ethylene;
or:
(IIf)
10 or:
100
(IIg)
or:
(IIh)
wherein:
5 R is methyl or hydrogen;
or:
(IIi)
or:
101
(IIj)
wherein:
R1 is tertiary butyl; R2 is hydrogen; R3 is 2,2-dimethylpropylene; and R4 is methyl,
ethyl, propyl, or butyl, preferably R4 is methyl.
5
38. The ligand of claim 32, wherein the ligand comprises at least one N-substituent,
and is selected from:
(IIa)
10 wherein:
R1 is tertiary butyl; R2 is hydrogen; R3 is 2,2-dimethylpropylene; and R4 is selected
from methyl, ethyl, propyl, or butyl;
or
102
(IIg)
or
(IIh)
(IIj)
5 Wherein
R1 is tertiary butyl; R2 is hydrogen; R3 is 2,2-dimethylpropylene; and R4 is
methyl, ethyl, propyl, or butyl.
103
39. A process of asymmetric N-substitution of a symmetrical ligand having a
tetraaminophenol coordination sphere, the process comprising the following
steps:
c) Protecting at least two of the amino groups of the coordination sphere of the
5 symmetrical ligand with an optionally substituted alkylene;
d) asymmetrically N-substituting one or more of the protected amino groups of
the product of step (a) with a substituent.
40. A process according to claim 39, wherein step (a) comprises reacting the
10 symmetrical ligand with a protecting reagent comprising an optionally
substituted alkylene group, preferably the protecting reagent is an aldehyde,
more preferably an aldehyde selected from formaldehyde or benzaldehyde.
41. A process according to claims 39 or 40, wherein step (a) comprises protecting
15 the amino groups of the coordination sphere of the symmetrical ligand by
forming bridging groups between the adjacent amino groups or amino and
phenolic groups.
42. A process according to any of claims 39 to 41, wherein step (b) comprises
20 asymmetrically N-substituting one or more of the protected amino groups of the
product of step (a) with an N-substituting agent by for example hydroamination
with an alkene or by using an alkylating agent.
43. A process according to claim 42, wherein the N-substituting agent is an
25 alkylating agent or an alkene such as an activated alkene for example alkyl
acrylate, alkyl methacrylate, alkyl vinyl ketone or acrylonitrile, more preferably
the alkylating agent comprises the formula R4X, wherein preferably X is a
halide, tosylate or triflate, more preferably X is iodine.
104
44. A process according to any of claims 39-43, wherein the process further
comprises step (c) hydrolysing the optionally substituted alkylene bridging
groups between the adjacent amino groups.
5 45. A process according to any of claims 39-44, wherein the asymmetrical ligand
produced by the process is that according to claim 38.
46. A process for the reaction of:
(i) carbon dioxide with an epoxide;
10 (ii) an epoxide and an anhydride; and/or
(iii) a lactide and/or a lactone,
in the presence of a catalyst as claimed in any one of claims 1 to 31, optionally
wherein the process is carried out in the presence of a chain transfer agent.
47. The process of claim 46, wherein the process is carried out in a continuous flow
15 reactor, or a batch reactor.
48. The process of claim 47, wherein the reaction is carried out in a continuous flow
reactor, preferably wherein M1 and M2 are selected from Ni(II) and Mg(II).
49. A product of the process of any of claims 46 to 48.
50. A catalyst, product or process substantially as hereinbefore defined with
20 reference to one or more of the examples.
Dated this 12th day of January, 2017
MOHAN DEWAN
of R.K. DEWAN & COMPANY
25 APPLICANT’S PATENT ATTORNEY
ABSTRACT
CATALYSTS
The present invention relates to the field of polymerisation catalysts, and
systems comprising said catalysts for polymerising carbon dioxide and an
epoxide, a lactide and/or lactone, and/or an epoxide and an anhydride. The
catalyst is of formula (I):
(I)
Wherein M1 and M2 are independently selected from Zn(II), Cr(II), Co(II), Cu(II),
Mn(II), Ni(II), Mg(II), Fe(II), Ti(II), V(II), Cr(III)-X, Co(III)-X, Ni(III)-X, Mn(III)-X,
Fe(III)-X, Ca(II), Ge(II), Al(III)-X, Ti(III)-X, V(III)-X, Ge(IV)-(X)2 or Ti(IV)-(X)2. R3A
is different from R3B; and/or at least one occurrence of E3, E4, E5 and E6 is
different to a remaining occurrence of E3, E4, E5 and E6. A ligand, a process of
asymmetric N-substitution of a symmetrical ligand and a process for the reaction
of:(i) carbon dioxide with an epoxide;(ii) an epoxide and an anhydride; and/or (iii)
a lactide and/or a lactone, in the presence of a catalyst is also described.