The present invention relates to substituted
piperazine compounds.
The present invention relates to compounds useful as
pharmaceuticals, to pharmaceutical compositions comprising
the compounds, to a process for preparing the compounds, to
intermediates useful in the preparation of the compounds,
and to use of the compounds as pharmaceuticals.
Cardiovascular disease continues to present a major
worldwide health problem, and is a common cause of serious
illness and death.
One line of investigation being pursued by researchers
in the search for new treatments for cardiovascular disease
is based upon the hypothesis that an inhibitor of the serine
protease, Factor Xa, may be useful as an anticoagulant agent
in the treatment of thrombotic disease.
Inhibitors of Factor Xa are known. For example,
WO 01/96323 disclose certain compounds containing an
atomatic group, a glycine residue that bears a cyclic group
and a 4-substituted piperazinyl group. The cyclic group may
be a cycloalkyl group, such as cyclopentyl or cyclohexyl,
but a preference is expressed for compounds in which the
cyclic group is a phenyl group.
Surprisingly, it has now been found that by selecting
from within the scope of WO 01/96323 a 4-methcxyphenyl or
3-fluoro-4-methoxyphenyl group as the aromatic group, a
cyclopropylglycine group as the glycine residue and a
l-methylpiperidin-4-ylpiperazinyl group as the 4-substituted
piperazinyl group, compounds may be obtained that are
selective Factor Xa inhibitors and have particularly
advantageous properties.
Accordingly, the present invention provides a compound
of formula (I)


in which R represents a hydrogen atom or a fluorine atom, or
a pharmaceutically acceptable salt thereof.
The compounds of formula (I) have been found to be
potent and selective inhibitors of the serine protease,
Factor Xa, to have good anticoagulant activity in human
plasma, to have good plasma exposure upon oral
administration to mammals, and to possess particularly
advantageous pharmacological and toxicological profiles of
activity.
The compounds of formula (I) may also be referred to by
the chemical names 1-(4-methoxybenzoyl-D-cyclopropyl-
glycinyl)-4-(l-methylpiperidin-4-yl)piperazine and 1-(3-
fluoro-4-methoxybenzoyl-D-cyclopropyl-glycinyl)-4-
(l-methylpiperidin-4-yl)piperazine.
It will be appreciated that the compounds of formula
(I) contain a center of asymmetry that has the (D)
configuration. The compounds may therefore exist and be
isolated in a mixture with the corresponding (L) isomer,
such as a racemic mixture, or separately. Preferably the
compounds are isolated substantially free of the (L)
isomers.
It will also be appreciated that the compounds of
formula (I) or their pharmaceutically acceptable salts may
be isolated in the form of solvates, and accordingly that

any such solvate is included within the scope of the present
invention.
Examples of pharmaceutically acceptable salts include
hydrochloride, fumarate and maleate acid addition salts.
It will be appreciated that the compounds of formula
(I) contain two basic nitrogen atoms and may therefore form
mono and di-acid addition salts.
One group of compounds of formula (I) is that in which
R is a hydrogen atom.
Particular compounds in which R represents a hydrogen
atom are:-
1- (4-methoxybenzoyl-D-cyclopropylglycinyl)-4-
(l~methylpiperidin-4-yl)piperazine and the hydrochloride,
fumarate and maleate acid addition salts thereof, especially
the dihydrochloride, difumarate and dimaleate acid addition
salts.
Crystalline dihydrochloride, difumarate and dimaleate
acid addition salts have been prepared and characterized by
differential scanning calorimetry (DSC):-
dihydrochloride: decomposes before melting;
difumarate: 222.8°C (onset), 225.4°C (peak); and
dimaleate: 195.S°C (onset), 202.0°C (peak).
Particular mention is made of 1-(4-methoxybenzoyl-D-
cyclopropylglycinyl)-4-(l-methylpiperidin-4-yl)piperazine
difumarate in crystalline form.
Another group of compounds of formula (I) is that in
which R is a fluorine atom.
Particular compounds in which R represents a fluorine
atom are:-
1- (3-fluoro-4-methoxybenzoyl-D-cyclopropylglycinyl)-4-
(l-methylpiperidin-4-yl)piperazine; and the hydrochloride
acid addition salts.

The compounds of formula (I) and their pharmaceutically
acceptable salts may be prepared by a process which
comprises:
(a) reacting a compound of formula (II)

or a salt thereof (such as the trihydrochloride), with a
compound of formula (III)

or a reactive derivative thereof; or
(b) reacting a compound of formula (IV)

or a salt thereof (such as the dihydrobromide), with a
compound of formula (V)

or a reactive derivative thereof;
followed, if a pharmaceutically acceptable salt is
desired, by forming a pharmaceutically acceptable salt.

The reaction between the compound of formula (II) with
the compound of formula (III) may conveniently be performed
employing reagents and reaction conditions conventionally
used for the formation of an amide bond. The reaction is
conveniently carried out in the presence of a benzotriazole-
based reagent such as 1-hydroxybenzotriazole or l-hydroxy-7-
azabenzotriazole and a dehydrating agent such as
dicyclohexylcarbodiimide or 1-(3-dimethylaminopropyl)-3-
ethylcarbodiimide, in an inert organic solvent such as
dimethylformamide and/or methylene chloride. The reaction
is conveniently conducted at a temperature of from 0 to
50 °C, preferably at ambient temperature. If a salt of a
compound of formula (II) is used, the reaction is
conveniently performed in the additional presence of a base
such as triethylamine. Other suitable reagents and solvents
are known in the art, for example an acid halide, such as
p-anisoyl chloride in the presence of a base, such as
triethylamine.
The reaction between the compound of formula (IV) with
the compound of formula (V) may conveniently be performed
employing reagents and reaction conditions conventionally
used for the formation of an amide bond, for example as
described above for the reaction of a compound of formula
(II) with a compound of formula (III).
The compounds of formula (II) may be prepared by
reacting a compound of formula (IV) with a compound of
formula (VI)

in which R1 represents an amino protecting group, such as
t-butoxycarbonyl (Boc) to afford a compound of formula (VII)


followed by removing the protecting group.
The compound of formula (IV) is known, and is also
referred to as 1-(l-methylpiperidin-4-yl)piperazine.
The compounds of formula (V) may be prepared by
reacting a compound of formula (VIII)

in which R2 represents a carboxyl protecting group, for
example a (l-6C)alkyl group, such as methyl or ethyl, with a
compound of formula (III) to afford a compound of formula"
(IX)

followed by removing the protecting group.
The compounds of formulae (VI) and (VIII) are known or
may be prepared from (D)-cyclopropylglycine using
conventional methods for the protection of the carboxy or
amino group in an amino acid. (D)-Cyclopropylglycine may
conveniently be prepared from cyclopropanecarboxaldehyde

using (R)-(+)-α-methylbenzylamine by the method described in
United States patent number 6,090,982, or by using a
procedure referenced therein.
The compounds of formula (III) are well known.
The protection of amino and carboxylic acid groups is
described in McOmie, Protecting Groups in Organic Chemistry,
Plenum Press, NY, 1973, and Greene and Wuts, Protecting
Groups in Organic Synthesis, 2nd. Ed., John Wiley & Sons,
NY, 1991. Examples of carboxy protecting groups include
C1-C6 alkyl groups such as methyl, ethyl, t-butyl and
t-amyl; aryl(C1-C4)alkyl groups such as benzyl, 4-nitro-
. benzyl, 4-methoxybenzyl, 3,4-dimethoxybenzyl, 2,, 4-dimethoxy-
benzyl, 2,4,6-trimethoxybenzyl, 2,4,6-trimethylbeneyl,
benzhydryl and trityl; silyl groups such as trimethylsilyl
and t-butyldimethylsilyi; and allyl groups such as allyl and
1-(trimethylsilylmethyl)prop-l-en-3-yl.
Examples of amine protecting groups include acyl
groups, such as groups of formula R3CO in which R3
represents C1-6 alkoxy, phenyl C1-6 alkoxy, or a C3-10
cycloalkoxy, wherein a phenyl group may be optionally
substituted, for example by one or two of halogen, C1-C4
alkyl and C1-C4 alkoxy.
Preferred amino protecting groups include
benzyloxycarbonyl (CBz) and t-butoxycarbonyl (Boc).
Certain of the intermediates described herein, for
example the compounds of formulae (II) and (V), are believed
to be novel and accordingly are provided as further aspects
of the invention.
The compounds of the invention may be administered by
any convenient route, e.g. into the gastrointestinal tract
(e.g. rectally or orally), the nose, lungs, musculature or
vasculature or transdermally. The compounds may be
administered in any convenient administrative form, e.g.
tablets, powders, capsules, solutions, dispersions,

suspensions, syrups, sprays, suppositories, gels, emulsions,
patches etc. Such compositions may contain components
conventional in pharmaceutical preparations, e.g. diluents,
carriers, pH modifiers, sweeteners, bulking agents, and
further active agents. If parenteral administration is
desired, the compositions will be sterile and in a solution
or suspension form suitable for injection or infusion. Such
compositions form a further aspect of the invention.
Viewed from this aspect the invention provides a
pharmaceutical composition, which comprises the compound of
formula (I) or a pharmaceutically acceptable salt thereof,
together, with a pharmaceutically acceptable diluent or
carrier.
According to another aspect, the present invention
provides the compound of formula (I) or a pharmaceutically
acceptable salt thereof, for use in therapy.
According to another aspect, the present invention
provides the use of the compound of formula (I) or a
pharmaceutically acceptable salt thereof, for the
manufacture of a medicament for the treatment of a
thrombotic disorder.
According to another aspect, the present invention
provides a method of treating a thrombotic disorder in a
subject requiring treatment, which comprises administering
an effective amount of a compound of formula (I) or a
pharmaceutically acceptable salt thereof.
The subject may be a human or a non-human animal, such
as a non-human mammal, for example a cat, dog, horse, cow or
sheep.
The thrombotic disorder may be, for example, venous
thrombosis, pulmonary embolism, arterial thrombosis,
myocardial ischaemia, myocardial infarction or cerebral
thrombosis. The compounds may also be used in accordance
with the method of the invention in the treatment of acute

vessel closure associated with thrombolytic therapy and
restenosis, for example after transluminal coronary
angioplasty or bypass grafting of the coronary or peripheral
arteries, and in the maintenance of vascular access patency
in long term hemodialysis patients.
The dosage of the compound of formula (I) will depend
upon the nature and severity of the condition being treated,
the administration route and the size and species of the
subject. In general, quantities in the range of from 0.01
to 100 µM/kg bodyweight will be administered.
As used herein, the term "treatment" includes
prophylactic use. The term "effective amount" refers to the
amount of the compound of formula (I) that is effective to
reduce or inhibit the development of the symptoms of the
thrombotic disorder being treated.
The compound according to the invention may be
administered alone or in combination with an anticoagulant
having a different mode of action or with a thrombolytic
agent.
The following Examples illustrate the invention.
Abbreviations used follow IUPAC-IUB nomencalture. The
following abbreviations are used throughout: Boc (tertiary-
butyloxycarbonyl), Calcd (calculated), DMSO (dimethyl •
sulfoxide, perdeuterated if for NMR), EDCI
(1-(3-dimethylaminopropyl)-3-ethylcarbodiimide
hydrochloride) , ES-MS (electron spray ioniazation mass
spectrum), HOBt (1-hydroxy-benzotriazole), HPLC (high-
performance liquid chromatography with tr as retention
time), MeOH (methanol), NMR (nuclear magnetic resonance),'
TEA (trifluoroacetic acid).
Example 1
1- (4-Methoxybenzoyl-D-cyclopropylglycinyl) -4- (1-methyl-
piperidin-4-yl)piperazine.

A. D-Cyclopropylglycine
The amino acid is obtained from cyclopropane-
carboxaldehyde, conveniently by using (R) - ( + ) -α-methyl-
benzylamine and the procedure of US Patent 6,090,982, or by
using a procedure referenced therein.
B. Boc-D-cyclopropylglycine
A solution of D-cyclopropylglycine (46.1 g, 0.4 mol) in
a mixture of dioxane (600 mL) , water (300 mL) and 1 N NaOH
(480 mL, 0.48 mol) is stirred cooled to 0-5 °C in an ice
bath. Di-tert-butyl dicarbonate (105 g, 0.48 mol) is added
slowly, and stirring is continued at room temperature for
0.5 h. The solution is concentrated in vacuo to about
500 mL, cooled in an ice-water bath, covered with a layer of
ethyl acetate (500 mL) and acidified with a dilute aqueous
solution of KHSO4 to pH 2-3. The aqueous phase is extracted
with ethyl acetate (500 mL) and the extraction repeated
until no product remains. The ethyl acetate extracts are
pooled, washed with water (0.5 L), brine (0.5 L), dried over
Na2SO4, filtered and concentrated to give a white solid
(78 g, 90.6 %) . [α]D20 = -31° (c=1.02, MeOH).
1H NMR (CDCI3) δ 5.9 (sb, 1H) , 5.09 (sb, 1H) , 3.-75 (m, 1H),
1.42 (s, 9H), 1.10 (d, 1H), 0.4-0.7 (m, 4H).
C. 1-(Boc-D-cyclopropylglycinyl)-4-(l-methylpiperidin-4-
yl)piperazine
Boc-D-cyclopropylglycine (216 g, 1.0 mol) and
1-(l-methylpiperidin-4-yl)piperazine (192 g, 1.05 mol) are
slurried in anhydrous CH2CI2 (3.2 L) under N2- The mixture
is then cooled to 0-5 °C in an ice bath. To this mixture,
1-hydroxybenzotriazole (HOBt) monohydrate (149 g, 1.1 mol)
and diisopropylethylamine (136 g, 1.05 mol) are added,
followed by slow addition of 1-[3-(dimethylamino)propyl]-3-

ethylcarbodiimide hydrochloride (EDCI) (211 g, 1.1 mol)
maintaining temp at 0-5 °C for 1 h. The reaction mixture is
allowed to warm to room temperature overnight. The reaction
is then quenched with the addition of saturated (satd)
aqueous NaHCO3 (3 L) and extracted with methylene chloride
(2 L). The layers are separated. The organic layer is
washed again with satd NaHCO3 (3 L) , brine (2 L) , dried over
MgSO4, filtered and concentrated to give the crude product
as a viscous oil (415 g, 109%) which is used directly.
1H NMR (DMSO-d6) 5 6.91 (d, 1H) , 3.97 (t, 1H) , 3.41 '(sb,
4H), 2.74 (d, 2H), 2.40 (sb, 4H), 2.10 (m, 1H), 2.09 (s,
3H), 1.79 (t, 2H), 1.65 (d, 2H) , 1.40 (m, 2H) 1.36 (s, 9H),
1.05 (m, 1H), 0.93 (d, 1H), 0.40 (m, 2H) , 0.26 (m, 1H) .
D. 1-(D-Cyclopropylglycinyl)-4-(l-methylpiperidin-4-yl)-
piperazine trihydrochloride
1-(Boc-D-cyclopropylglycinyl)-4-(l-methylpiperidin-4-
yl)piperazine (crude, 415 g, 1.0 mol) is dissolved in
anhydrous methanol (1.5 L). To this solution is added HC1-
MeOH (380 g/1.5 L, 10.4 mol) solution at 0 °C. The reaction
mixture is stirred and slowly warmed to room temperature for
2 h. Ethyl acetate (2 L) is then added with stirring.
Stirring is continued for 1 h at 0-5 °C, and product
precipitates out as a white powder which is filtered and
dried under vacuum at 45 °C to give the title compound as a
white solid (357 g, 91.7%).
1H NMR (DMSO-d6+D20) 5 8.4 (bs, 1H), 4.5 (bs, 2H) , 3.0 (t,
4H), 2.78 (m, 1H), 2.74 (s, 3H), 2.35 (m, 2H), 2.20 (m, 1H),
2.08 (m, 2H), 1.06 (bd, 1H), 0.60 (m, 4H).
E. 1-(4-Methoxybenzoyl-D-cyclopropylglycinyl)-4-(1-methyl-
piperidin-4-yl)piperazine

1-(D-Cyclopropylglycinyl)-4-(l-methylpiperidin-4-yl)-
piperazine trihydrochloride (300 g, 0.77 mol) is slurried in
anhydrous CH2CI2 (3 L) under N2 The mixture is then cooled
to 0-5 °C in an ice bath. Triethylamine (450 mL, 3.23 mol)
is added slowly while maintaining the temperature at 0-5 °C,
followed by slow addition of p-anisoyl chloride (142 g, 0.83
mol), again maintaining the temperature at 0-5 °C. The
reaction mixture is allowed to warm to room temperature for
2 h. The reaction is then quenched with the addition of
satd NaHCO3 (1 L) , and the layers are separated. The
aqueous layer is then extracted with CH2CI2 (2 L). The
organic layers are combined, washed with brine (1 L), dried
over MgSO4, filtered and concentrated to give the title
compound (326 g, 102%).
1H NMR (DMSO-d6) 5 8.55 (d, J = 7.7 Hz, 1H), 7.88 (d, 2H) ,
6.96 (d, 2H), 4.39 (t, 1H), 3.79 (s, 3H) , 3.45 (s, 4H), 2.74
(d, 2H), 2.40 (m, 4H) , 2.09 (s, 3H) , 2.08 (m, 1H), 1-79 (dt,
2H), 1.62 (d, 2H), 1.38 (m, 2H), 1.26 (m, 1H), 0.43 (m, 2H),
0.35 (m, 2H) .
Example la
1- (4-Methoxyben.zoyl-D-cyclopropylglycinyl) -4- (1-methyl-
piperid.in-4-yl) piperazine difumarate
To a solution of 1-(4-methoxybenzoyl-D-cyclopropyI-
glycinyl)-4-(l-methylpiperidin-4-yl)piperazine (315 g, 0.76
mol) in 95% ethanol (4.2 L) warmed to 65 °C is added a
solution of fumaric acid (177 g, 1.52 mol) in hot ethanol
(at 65 °C, 2.8 L). The final clear solution is stirred at
65 °C and slowly cooled down to room temperature (over two
hours) and then to 0-5 °C. The white crystals are collected
by filtration, washed with 95% ethanol (1 L), and dried
under vacuum at 45 °C to provide the title salt (448 g,
91.2%), mp=205-207 °C.

1H NMR (DMSO-d6) δ 11.35 (s, 1H) , 8.58 (d, 1H) , 7.86 (d,
2H), 6.96 (d, 2H), 6.55 (s, 4H), 4.39 (t, 1H) , 3.79 (s, 3H) ,
3.45 (s, 4H), 3.20 (d, 2H) , 2.62 (t, 2H) , 2.55 (s, 3H), 2.42
(m, 6H) , 1.80 (d, 2H) , 1.62 (d, 2H) , 1.28 (m, 1H) , 0.43 (m,
2H), 0.35 (m, 2H).
[α]D20 = -37.7° (c=0.836, H2O) .
Example lb
1-(4-Methoxybenzoyl-D-cyclopropylglcinyl) -4-(1-methyl-
piperidin-4-yl)piperazine Hydrochloride.
1-(4-Methoxybenzoyl-D-cyclopropylglcinyl)-4-(1-methyl-
piperidin-4-yl)piperazine (3.04 g, 6.73 mmol) is dissolved
in approximately 0.2 M HC1 (37 mL) and lyophilized to give
2.98 g (quantitative) of the title compound.
Partial 1H NMR Spectrum (DMSO-d6) 5 10.63 (br, 1H) , 8.59
(br, 1H), 7.88 (d, 2H), 6.98 (d, 2H), 4.36 (br t, 1H), 3.82
(s, 3H) , 2.70 (s, 3H) , 1.29 (m, 1H) , 0.48 (m, 2H) , 0.36
(m, 2H).
ES-MS, m/z 415.5 (M+l)+.
Analysis for C23H34N4O3■1.25 HC1•1.0 H2O:
Calcd: C 57.78; H 7.85; N 11.72; CI 9.30;
Found: C 57.79; H 7.93; N 11.74; CI 9.64.
Analytical HPLC (Xterra RP18, 4.6x150 cm,
10% acetonitrile/water (0.1% TFA) through
50% acetonitrile/water (0.1 % TFA) over 40 min), 1 mL/min:
99%, tr = 10.66 min
Example 2
1-[(3-Fluoro-4-methoxybenzoyl)-D-cyclopropylglcinyl]-
4-(1-me thylpiperidin-4-yl)piperazine.

To a stirring suspension of l-D-cyclopropylglcinyl-4-
(l-methylpiperidin-4-yl)piperazine trihydrochloride (1.5 g,
3.85 mmol) in dichloromethane (30 mL) is added triethylamine
(1.36 g, 13.5 mmol) followed by 3-fluoro-4-methoxybenzoic
acid (0.622 g, 3.66 mmol), HOBt (0.573 g, 4.24 mmol) and
EDCI (0.813 g, 4.24 mmol). After stirring overnight, the
mixture is partitioned between dichloromethane and saturated
aqueous sodium bicarbonate. The organic phase is then
washed again with saturated aqueous sodium bicarbonate,
followed by brine, then dried with MgSO4, filtered and
concentrated in vacuo. The residue is then dissolved in
dichloromethane and chromatographed over silica gel, eluting
with a'-tgradient of 0-12% 2 N ammonia/methanol in
dichloromethane. The pure product containing fractions are
combined and concentrated in vacuo to give 1.03 g (61%) of
the title compound.
ES-MS, m/z 433.5 (M+l)+.
Analytical HPLC (Vydac C18, 4.6x150 cm,
10% acetonitrile/water (0.1% TFA) through
50% acetonitrile/water (0.1 % TFA) over 40 min), 1 mL/min:
95%, tr = 13.16 min
Example 2 a
1- [ (3-Fluoro-4-methoxybenzoyl) -D-cyclopropylglcinyl] -
4- (l-methylpiperidin-4-yl) piperazine Hydrochloride .
1- [ (3-Fluoro-4-methoxybenzoyl)-D-cyclopropylglcinyl]-4-
(l-methylpiperidin-4-yl)piperazine (1 g, 2.31 mmol) is
dissolved in approximately 0.2 M HCl (12.7 mL) and
lyophilized to give 1.03 g (quantitative) of the title
compound.

Partial 1H NMR Spectrum (DMSO-d6) 5 10.36 (br, 1H), 8.73 (d,
1H), 7.75-7.83 (m, 2H) , 7.25 (t, 1H) , 4.36 (t, 1H), 3.90 (s,
3H), 2.70 (s, 3H), 1.28 (m, 1H) , 0.48 (m, 2H) , 0.36 (m, 2H) .
ES-MS, m/z 433.3 (M+l)+.
Analysis For C23H33FN4O3•1.6 HC1•0.5 H2O:
Calcd: C 55.26/ H 7.18; N 11.21; F 3.80; CI 11.35;
Found: C 55.31; H 7.24; N 11.38; F 3.64; CI 11.36.
Analytical HPLC (Xterra RP18, 4.6x150 cm,
10% acetonitrile/water (0.1% TFA) through
50% acetonitrile/water (0.1 1% TFA) over 40 min), 1 mL/min:
98%, tr = 8.067 min.
Enzyme Inhibition assays:
The ability of a test compound to inhibit factor Xa may
be evaluated in one or more of the following Enzyme
Inhibition assays, or in other standard assays known to
those skilled in the art.
Enzyme Inhibition Assay-
Human factor Xa and human thrombin are purchased from
Enzyme Research Laboratories (South Bend, Indiana, USA) .
Other proteases are from other commercial sources.
Chromogenic para-nitroanilide peptide protease substrates
are purchased from Midwest Biotech (Fishers, Indiana, USA).
The binding affinities for human factor Xa are were
measured as apparent association constants (Kass) derived
from protease inhibition kinetics as described
previously.a,b,c, d the apparent Kass values are obtained
using automated (BioMek-1000) dilutions of inhibitors (Kass
determinations are performed in triplicate at each of four-
eight inhibitor concentrations) into 96-well plates and
chromogenic substrate hydrolysis rates determined at 4 05 nm
using a Thermoraax plate reader from Molecular Devices (San
Francisco). For factor Xa inhibition, the assay protocol

is: 50 μL buffer (0.06 M tris, 0.3 M NaCl, pH 7.4); 25 μL
inhibitor test solution (in MeOH) ; 25 μL human factor Xa
(32 nM in 0.03 M tris, 0.15 M NaCl, 1 mg/mL HSA); finally,
150 uL BzIleGluGlyArgpNA (0.3 mM in water) added within 2
min to start hydrolysis. Final [factor Xa] is 3.2 nM.
[Free Xa] and [bound Xa] are determined from linear standard
curves on the same plate by use of SoftmaxPro software for
each inhibitor concentration and apparent Kass calculated
for each inhibitor concentration which produced hydrolysis
inhibition between 20% and 80% of the control (3.2 nM factor
Xa) : apparent Kass = [E : I] / [Ef ] [If ] = [Eb] / [Ef ] [I°-Ib] .
The apparent Kass values so obtained are approximately the
inverse of the Ki for the respective inhibitors [1/appKass =
app Ki]. The variability of mean apparent Kass values
determined at the single substrate concentration is +/- 15%.
The assay system Km was measured as 0.347 +/- 0.031 mM
[n=4]; and Vmax was 13.11 +/- 0.7 6 fiM/min.
Kass values are determined with thrombin and other
proteases using the same protocol with the following enzyme
and substrate concentrations:
thrombin, 5.9 nM with 0.2 mM BzPheValArgpNA;
factor XIa, 1.2 nM with 0.4 mM pyroGluProArgpNA;
factor Xlla, 10 nM with 0.2 mM HDProPheArgpNA;
plasmin, 3.4 nM with 0.5 mM HDValLeuLyspNA;
nt-PA, 1.2 nM with 0.8 mM HDIleProArgpNA;
urokinase, 0.4 nM with 0.4 mM pyroGluGlyArgpNA;
aPC, 3 nM with 0.174 mM pyroGluProArgpNA;
plasma kallikrein, 1.9 nM with D-ProPheArgpNA; and
bovine trypsin, 1.4 nM with 0.18 mM BzPheValArgpNA.
Citations
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Chirgadze, DK Clawson, ML Denny, DD Giera, DS Gifford-

Moore, RW Harper, KL Hauser, VJ Klimkowski, TJ Kohn, H-
S Lin, JR McCowan, AD Palkowitz, GF Smith, ME Richett,
K Takeuchi, KJ Thrasher, JM Tinsley, BG Utterback, S-CB
Yan, M Zhang. Dibasic Benzo[b]thiophenes Derivatives
as a Novel Class of Active Site Directed Thrombin
Inhibitors. 1. Determination of the Serine Protease
Selectivity, Structure-Activity Relationships and
Binding Orientation. J Med Chem 40 3489-3493 (1997) .
(b) Smith GF, TJ Craft, DS Gifford-Moore, WJ Coffman, KD
Kurz, E Roberts, RT Shaman, GE Sandusky, ND Jones, N
Chirgadze, and CV Jackson. A Family,.of Arginal Thrombin
Inhibitors Related to Efegatran. Sem. Torombos. Hemost. 22,
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(c) Smith GF, DS Gifford-Moore, TJ Craft, N Chirgadze, KJ
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Snyder, K Takeuchi, JE Toth, M Zang. Diamino
Benzo[b]thiophene Derivatives as a Novel Class of Active
Site Directed Thrombin Inhibitors: 5. Potency, Efficacy
and Pharmacokinetic Properties of Modified C-3 Side Chain
Derivatives. J. Med. Chem., 43, 649-663 (2000).
The compounds of formula (I) exemplified herein have
been found to exhibit a Kass of about 14 x 106 to 35 x 106
L/mole in the enzyme inhibition assay.

The ability of a test compound to elongate Partial
Thromboplastin Time (Prothrombin Time) may be evaluated in
the following test protocols.
Partial Thromboplastin Time (Prothrombin) Test Protocol
Venous blood is collected into 3.2% (0.109 M) trisodium
citrate vacutainer tubes at 1 volume of anticoagulant to
nine volumes of blood. The blood cells are separated by
centrifugation at 700 g for ten minutes to yield plasma,
which is frozen at 70 °C until required.
To perform the test, 100 μL of plasma are pipetted into
in a glass test tube, 1 uL of test compound in DMSO is
wadded, and allowed to warm to 37 ° over two minutes. 100 μL
of warm (37 °) Manchester (tissue thromboplasin) reagent
(Helena Biosciences, UK) is added, allowed to equilibrate
for two minutes. 100 μL of warm (37 °) 25mM calcium
chloride solution is added to initiate clotting. The test
tube is tilted three times through a 90° angle every five
seconds to mix the reagents and the time to clot formation
recorded. Data from a series of observations and test
compound concentrations are analysed by a SAS statistical
analysis program and a CT2 (Concentration required to double
clotting time) for each compound is generated.
The compounds of the invention have been found to
significantly elongate the partial thromboplastin time
(Prothrombin time).
Alternative Prothrombin Time and APTT Protocols
Coagulation Determinations: Prothrombin Times and APTT
values are determined in HUMAN PLASMA with a STA instrument
(Stago). BioPT is a special non-plasma clotting assay
triggered with human tissue factor (Innovin). Possible
binding to albumen or to lipid are assessed by comparing the

BioPT effects in the presence/absence of 30 mg/mL human
albumen (HSA) and 1 mg/mL phosphatidyl choline (PC).
Inhibitors are delivered in 50% aqueous methanol vehicle.
APTT ASSAY
75 uL plasma Citrol Baxter-Dade Citrated Normal
Human Plasma
25 uL test solution
7 5 μL Actin Baxter-Dade Activated Cephaloplastin incubate 2
min min. @ 37 °C
75 μl CaCl2 (0.02 M)
PT ASSAY
7 5 μL plasma
25 μL test solution
75 μL saline incubate 1 min. @ 37° C
75 μL Innovin Baxter-Dade Recombinant Human Tissue Factor
Further advantageous properties of compounds of formula
(I) may be demonstrated by measuring their pharmacodynamic
(PD) and pharmacokinetic (PK) properties in-laboratory
animal species such as rats and dogs following oral dosing
in the fasted and in the fed state.


We Claim:
1. A compound of formula (1)

in which R represents a hydrogen atom, or a fluorine atom, or
a pharmaceutically acceptable salt thereof.
2. A compound as claimed in Claim 1, in which R represents
a hydrogen atom.
3. A compound as claimed in Claim 2, which is selected
from
1- (4-methoxybenzoyl-D-cyclopropylglycinyl> -4-
(l-methylpiperidin-4-yl)piperazine and the hydrochloride,
tumarate And. maleate acid addition salts thereof.
3. A compound as claimed in Claim 3, which is selected
from the dihydrochloride, difumrate and dimalcate acid
addition salts in crystalline form.
5. A compound as claimed in Claim 4, which is l-{4-
methoxybenzoyl-D-cyclopropylglycinyl)-4-(l-methylpiperidin-
4-yl)piperazine difumarate in crystalline form.
6. A compound as claimed in Claim 1, in which R represents
a fluorine atom.

7. A compound as claimed in Claim 6, which is selected
from:-
1-[3-fluoro-4-methoxybenzoyl-D-cyclopropylglycinyl)-4 -
(l-methylpiperidin-4-yl)piperazine; and the hydrochloride
acid addition salts thereof.
8. A pharmaceutical composition, which comprises a
compound as claimed in any one of Claims 1 to 7, together
with a pharmaceutically acceptable diluent or carrier.
9. A process for preparing a compound as claimed in any
one of Claims 1 to 7, which comprises:
(a) reacting a compound of formula (11)

or a salt thereof, with a compound of formula (III)

or a reactive derivative thereof; or
(b) reacting a compound of formula (IV)

or a salt thereof, with a compound of formula (V)


or a reactove derivative thereof;
followed, if a pharmaceutically acceptable salt is
desired, by forming a pharmaceutically acceptable salt.
10. A compound of formula (II)

or a salt thereof.
11. A compound of formula (V)

12. A compound of claimed in any one of Claims 1 to 7, for
the therepy.
13. A compound as claimed in claim 1, wherein the compound is
comprised in a medicament useful against thrombotic disorder.

The compounds of formula (I) in which R represents a hydrogen atom or a fluorine atom, or a pharmaceutically acceptable salt thereof are FactorXa inhibitors useful in the treatment of thrombotic disorders.