FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; Rule 13)
TITLE
PROCESS FOR THE SYNTHESIS OF PROPARGYLATED AMINOINDAN DERIVATIVES
APPLICANT
CIPLA LIMITED
AN INDIAN COMPANY
OF 289 BELLASIS ROAD, MUMBAI CENTRAL,MUMBAI 400 008,
MAHARASHTRA
INDIA
The following specification particularly describes the nature of the invention and the manner in which it is performed.

Process for the synthesis of propargvlated aminoindan derivatives.
Field of the Invention
5 The present invention relates to a improved and industrially safe process for the synthesis of propargylated aminoindan derivatives. More particularly it relates to (iR)-N-prop-2-ynyl-2,3-dihydro-1H-inden-1-amine.
Background of the Invention.
10
(1R)-N-prop-2-Ynyl-2,3-dihydro-1H-inden-1-amine (I) also termed as Rasagiline or (R) N-propargyl 1-indanamine is an irreversible inhibitor of monoamine oxidase used as a monotherapy in early Parkinson's disease or as an adjunct therapy in more advanced cases.
15

Racemic propargyl-1-aminoindan hydrochloride was described in GB1003676, GB1037014, US3513244. In the prior art the racemic mixture of propargyl-1-20 aminoindane was prepared by reacting l-chloroindane or l-bromoindane with propargylamine
The R-enantiomer of rasagiline was described in EP0436492 and EP0812190 and the process disclosed comprises reacting optically active R-enantiomer of 1-25 aminoindan with propargyl bromide or propargyl chloride in presence of an organic or inorganic base and optionally in the presence of a solvent.
US 5532415 discloses rasagiline R(+)-N-propargyl-1-aminoindan, its preparation, and various pharmaceutically acceptable salts thereof. US 5532415 discloses that an enantiomerically pure aminoindan derivatives may be obtained by optical resolution

of racemic mixtures of R-and S-enantiomers of propargyl aminoindan derivatives. Such a resolution can be accomplished by any conventional resolution method well known to a person skilled in the art. For example, the resolution may be carried out by preparative chromatography on a chiral column.
5 US 5532415 further describes how an enantiomerically pure propargyl aminoindan can also be prepared directly from the optically active R-enantiomer of l-aminoindan by reaction with propargyl bromide or propargyl chloride or a propargyl sulfonate ester in the presence of an organic or inorganic base, like triethylamine, pyridine, alkali metal carbonates, and bicarbonates and optionally in the presence of a suitable 10 solvent chosen from, e.g., toluene, methylene chloride, and acetonitrile.
The process for preparation and separation of aminoindan derivatives described in the prior art have their shortcomings. Chromatography is difficult to scale up because of the large quantities of solvents used, which are difficult to dispose of. It is very difficult to carry out distillation of the high boiling aminoindan derivatives. 15 Further use of propargyl chloride or bromide is a very difficult because it is highly toxic flammable liquid. It is decompose explosively with shock and heat hence is not suitable for an industrial scale up.
The aim of the present invention is to provide an alternative and improved process which helps to overcome the shortcomings associated with the prior art processes.
Summary of the invention.
It is an object of the present invention to provide an improved process for the synthesis of propargylated aminoindan derivatives and their salts.
It is another object of the present invention to provide an industrially safe process for the preparation of rasagiline or its salts, which excludes the use of toxic reagents.

Detailed Description of the invention.
The above objects are achieved in accordance with various aspects of the present invention.
According to one aspect the present invention provides a process which comprises reacting racemic aminoindan of formula (II) or its enantiomer with an allyl halide preferably allybromide in presence of a base and an organic solvent, preferably at a temperature ranging from 25 °C to the reflux temperature of the solvent, to give compound of formula (III). The compound of formula (III) may be optionally isolated as an acid addition salt preferably an organic acid like succinic acid, methanesulphonic acid, tartaric acid, benzoic acid, most preferably oxalic acid.

The invention also provides compounds of formulas (III) and (IV), which are new compounds.
The base is preferably an alkali metal hydroxide or carbonate, most preferably 20 potassium carbonate. The organic solvent is preferably a C1 to C4 alcohol, especially isopropyl alcohol, tetrahydrofuran or acetonitrile. The preferred solvent is acetonitrile.

Compound (III) is further reacted with a halogenating reagent, preferably bromine, in a suitable organic solvent to give a dihalo compound of formula (IV).
The halogenation may be carried out with a halogen other than bromine, if desired.

The solvent is preferably toluene, xylene, dioxan or dichloromethane, most preferably dichloromethane.
The dihalo compound (IV) is treated with a suitable base, like alkali or alkaline earth metal hydroxide or alkoxide, to give compound (V).

The base used to treat the dibromo compound (IV) is preferably an alkali or alkaline earth metal hydroxide, preferably potassium hydroxide. This reaction is preferably carried out in the presence of a solvent selected from C1 to C4 alcohol or a C1 to C4 alcohol-water mixture. The C1 to C4 alcohol is preferably isopropyl alcohol. The compound of formula (V) may be converted to a pharmaceutically acceptable salt.

In each of the above three reactions an enantiomer of the compounds (II), (III) or (IV) may be employed instead of the racemate, especially the R-enantiomer.
According to another aspect of the present invention there is provided an improved and safe synthesis of (R) N-propargyl 1-indanamine (I) which comprises reacting (R) l- aminoindan with allyl bromide using a base, preferably an alkali metal hydroxide or carbonate, most preferably potassium carbonate, in presence of an organic solvent, preferably at a temperature ranging from 25 °C to the reflux temperature of the solvent used, to give a R-(-)N-allyl-1-aminoindan which can be optionally isolated as an organic acid addition acid salt preferably oxalate salt. The organic solvent is preferably a C1 to C4 alcohol, especially isopropyl alcohol, tetrahydrofuran or acetonitrile. The preferred solvent is acetonitrile. Allyl chloride may be used as an alternative to allyl bromide.
R-(-) N-allyl-1-aminoindan is further reacted with bromine or chlorine in a suitable organic solvent, to get R-(-)N-(2,3-dibromo propyl)-1-aminoindan. The solvent is preferably toluene, xylene, dioxan or dichloromethane, most preferably dichloromethane.
The R-(-)N-(2,3-dibromo propyl)~i-aminomdan is then heated in a suitable solvent presence of base to give (R)- N-propargyl i-indanamine (I) which can be converted to its salts. The base is preferably an alkali or alkaline earth metal hydroxide, preferably potassium hydroxide. The solvent is preferably selected from C1 to C4 alcohol or a C1 to C4 alcohol-water mixture. The C1 to C4 alcohol is preferably
isopropyl alcohol. The compound of formula (V) may be converted to a pharmaceutically acceptable salt.
This aspect of the invention is presented in the scheme below


In another aspect (R) N-propargyl l-indan amine can be prepared by resolution of the racemic N-propargyl l-indanamine prepared by the process of the present invention using a suitable resolving agent, preferably L-tartaric acid. Typically in this aspect of the present invention (R) N-propargyl l-indanamine (I) is prepared by the process as described above, more particularly by reacting 1- aminoindan with allyl bromide using a base preferably potassium carbonate in presence of an organic solvent preferably acetonitrile at a temperature ranging from 25 °C to the reflux temperature
of the solvent used, to give N-allyl-1-aminoindan which can be optionally isolated as an organic acid addition acid salt preferably oxalate salt. N-allyl-l-aminoindan is further reacted with bromine in a suitable organic solvent preferably dichloromethane to get N-(2,3-dibromo propyl)-i-aminoindan which is then heated in a suitable solvent presence of base to give racemic N-propargyl l-indanamine,
which is resolved using a suitable resolving agent preferably L-tartaric acid to give (R) N-propargyl l-indanamine which can be converted to its pharmaceutically acceptable salts.
In another aspect the present invention provides a process for the resolution of the racemic intermediates (III) and (IV) using a chiral resolving agent selected from the corresponding chiral acid of tartaric acid, dipara toluyl tartaric acid, camphorsulphonic acid, mandelic acid and the like.

Another aspect of the present invention is to provide an alternate process for the synthesis of rasagiline which comprises reacting l-aminoindan with halo acetone to get compound of formula (VI) which is brominated to give dibromo intermediate of formula (VII) which when further treated with base give rasagiline as depicted in the scheme below.

Resolution of the intermediate of formula (VI and (VII) using a chiral resolving agent selected from the corresponding chiral acid of tartaric acid, dipara toluyl tartaric acid, camphorsulphonic acid, mandelic acid and the like and further converting it to the corresponding enantiomer of rasagiline forms another aspect of the present invention.
In yet another aspect the present invention provides an improved process for the synthesis of N-ethyl-N-methylcarbamic acid 3(i?)-(2-propylamino)-2,3-dihydro-1H-inden-5-yl ester L-tartrate (I) which comprises following the process as given in scheme below.


According to another aspect of the invention there is provided a process for preparing a compound of formula (III) fay reacting a compound of formula (II) with an allyl bromide or other allyl halide, in accordance with the following scheme:

According to another aspect of the invention there is provided a process for preparing a compound of formula (IV) by reacting a compound of formula (III) with a bromine or other halogen, in accordance with the following scheme:


According to another aspect of the invention there is provided a process for preparing a compound of formula (V) by treating a compound of formula (IV) with a suitable base, in accordance with the following scheme:

In each of the above three reactions an enantiomer of the compounds (II), (III) or (IV) may be employed instead of the racemate, especially the R-enantiomer. The conditions for the reactions are preferable the same as described above.
This invention will be better understood by the following examples. However, the examples illustrate, but do not limit the scope of the invention. Those skilled in the filed of the art will readily appreciate that the specific methods and results discussed are merely illustrative of the invention as described more in the claims that follow thereafter.

Examples
Example-1
To the stirred solution of (R)- 1-aminoindan (loogm) in 1000 ml of acetonitrile was added 100 gm of potassium carbonate. The resulting suspension was stirred at 60° C to 70°C. Allyl bromide (60 gm) was added dropwise to the reaction mass at 60-70 °C. The reaction mass stirred was further stirred at reflux temp for about 12-13 hrs. The reaction mass was then quenched in 2.5 lit of water and later extracted with 500 10 ml of ethyl acetate. The organic phase was dried over sodium sulphate. 125 gm of oxalic acid was added to the ethyl acetate layer at 25-30 °C. The resulting precipitate was at 25-30° C for 2 hrs & filtered. The solid was recrystalized from methanol to yield 100 gm of R(-)N-allyl-1-aminoindan oxalate.
Exarnple-2
R-(-)N-allyl-i-aminoindan oxalate salt (loogm) was suspended in 1000 ml of dichloromethane, 500ml of 10% NaOH solution was added to the suspension slowly.
The organic layer was washed with water and dried over sodium sulphate & concentrated under vacuum to about 500ml. To the organic phase was added bromine (6ogm dissolved in 250 ml of dichloromethane) at 0-5 °C dropwise After completion of addition the reaction mass was stirred at 25-30 °C for about lhr. The reaction mass was quenched into 2.5 lit water. Organic phase was separated and
washed with 250ml 10% NaOH solution, the organic phase was dried over sodium sulphate and concentrated to residue to yield (lisgm) of R-(-) N-(2,3 dibromo propylM-aminomdan
Example-3
R-(-)N-(2,3 dibromo propyl)-1-aminoindan (lisgm) was dissolved in 500 ml denatured industrial spirit, 100ml water was added followed by 100 gm potassium hydroxide. The mixture was heated to 80-90 C for 5 hrs. The reaction mass was

quenched into 2.5 lit water and extracted with 250 ml ethyl acetate three times. The combined organic phase was dried over sodium sulphate & concentrated to about 500ml-100 gm oxalic acid was added to the ethyl acetate concentrate under stirring at 25-30° C and stirred for 1 hr. The resulting precipitated was isolated by filtration to yield 50 gm of (R)- N-propargyl 1-indanamine oxalate.
Example 4
1-aminoindan (loogm) was stirred in 1000 ml of acetonitrile 100 gm of potassium carbonate was added and was stirred at 60 °C to 70°C. Allyl bromide (60 gm) was added slowly to the reaction mass at 60-70 °C. The reaction mass was refluxed for about 12-13 hrs. The reaction mass was then quenched in 2.5 lit of water and later extracted with 500 ml of ethyl acetate. The organic phase was dried over sodium sulphate. 125 gm of oxalic acid was added to the ethyl acetate layer at 25-30°C. The resulting precipitate was at 25-30°C for 2 hrs & filtered. The solid was recrystalized from methanol to yield 100 gm of the N-allyl-1-aminoindan oxalate.
Example-.5
N-allyl-1-aminoindan oxalate salt (loogm) was suspended in 1000 ml of dichloromethane, 500ml of 10% NaOH solution was added to the suspension slowly. The organic layer was washed with water and dried over sodium sulphate & concentrated under vacuum to about 500ml. To the organic phase was added bromine (6ogm dissolved in 250 ml of dichloromethane) at 0-5 °C dropwise After
completion of addition the reaction mass was stirred at 25-30 °C for about lhr. The reaction mass was quenched into 2,5 lit water. Organic phase was separated and washed with 250ml 10% NaOH solution, the organic phase was dried over sodium sulphate and concentrated to residue to yield (lisgm) N-(2,3 dibromo propylV1-aminoindan.

Example -6
N-(2,3 dibrorno propyl)-1-aminoindan (100 gms) was dissolved in isopropyl alcohol (200ml) at 25-30C. L-tartaric acid (20 gm) dissolved in (250 ml) of water was added 5 at 25-30 C and the reaction mass was heated at 6o°C for 30 min. and cooled to 25-30 C under stirring. The resulting suspension was filtered. This solid was refiuxed under stiiring in a mixture of methanol: isopropyl alcohol 1 :1 (500ml). The slurry was cooled at 0-5 °C and filtered to give R-(-)N-(2,3 dibrorno propyl)-l-aminoindan as a tartrate salt. 10
Example- 7
N-allyl-1-aminoindan (10 gms) was dissolved in isopropyl alcohol (50ml) at 25-30C. L-tartaric acid (3.6 gm) dissolved in (5.5 ml) of water was added at 25-30 C and the 15 reaction mass was heated at 6o°C for 30 min. and cooled to 25-30 C under stirring. The resulting suspension was filtered. This solid was refiuxed under stiiring in a mixture of methanol : isopropyl alcohol 1 :1 (50ml). The slurry was cooled at 0-5 °C and filtered to give R-(-) N-allyl-1-aminoindan tartrate.
Example-8
N-(2,3 dibrorno propyl)-1-aminoindan (nsgm) was dissolved in 500 ml denatured industrial spirit, lOOml water was added followed by 100 gm potassium hydroxide. The mixture was heated to 80-90 C for 5 hrs. The reaction mass was quenched into
2.5 lit water and extracted with 250 ml ethyl acetate. The organic phase was dried & concentrated to residue. The residue was dissolved in isopropyl alcohol (160ml) at 25-30C. L-tartaric acid (13.5gm) dissolved in (20 ml ) of water was added at 25-30 C and the reaction mass was heated at 6o°C for 30 min. and cooled to 25-30 C under stirring. The resulting suspension was filtered. This solid was refiuxed under stiiring
in a mixture of methanol: isopropyl alcohol 1 :1 (300ml). The slurry was cooled at O-5 °C and filtered.This solid was further stirred with 10% sodium hydroxide solution and extracted with dichloro methane 250ml. The organic layer was separated, dried and concentrated under vacuum to residue. The residue is dissolved in isopropyl

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alcohol and 5.7 ml methane sulphonic acid was added dropwise at 25-30 C. The resulting suspension was cooled to 0-5 °C and filtered. The solid was further recrystallised from isopropyl alcohol to get 10 gms (K) N-propargvl 1-indanamine mesylate HPLC (99.8%) Chiral purity (99.5%).

CLAIMS:
1. A process for preparing N-propargyl l-indanamine or its enantiomer, which
comprises:
(a) reacting racemic l-aminoindan or its enantiomer with an allyhalide in
presence of a base to give N-allyl-1-aminoindan or its enantiomer;
(b) halogenating the N-allyl-1-aminoindan or its enantiomer with a
halogenating agent in a suitable organic solvent to give N-(2,3 dihalo propyl)-1-
aminoindan or its enantiomer; and
(c) treating the N-(2,3-dihalo propyl)-1-aminoindan or its enantiomer with a
suitable base to give N-propargyl 1-indanamme or its enantiomer.
2. A process according to claim l, wherein the base used in step (a) is an alkali
metal carbonate.
3. A process according to claim 1 or 2, wherein the base used in step (a) is
potassium carbonate.
4. A process according to claim 1, 2 or 3, wherein the organic solvent used in step
(a) is a C1 to C4 alcohol, tetrahydrofuran or acetonitrile.
5. A process according to any preceding claim, wherein the organic solvent used
in step (b) is toluene, xylene, dioxan or dichloromethane.
6. A process according to any preceding claim, wherein the base used in step (c) is an alkali or alkaline earth metal hydroxide or alkoxide.
7. A process according to any preceding claim, wherein the base used in step (c)
is potassium hydroxide.
8. A process according to any preceding claim, wherein step (c) is carried out in
the presence of a solvent selected from C1 to C4 alcohol or a C1 to C4 alcohol-water
mixture.

g. A process according to any preceding claim, wherein the allyl halide is allyl bromide.
10. A process according to any preceding claim, wherein the halogen used in step (b) is bromine.
11. A process according to any preceding claim, wherein step (a) is carried out at a
temperature from 25°C up to the reflux temperature of the solvent used in step (a).
12. A process according to any preceding claim, wherein the N-allyl-1-aminoindan
is formed as an acid addition salt thereof.
13. A process according to any preceding claim, wherein the l-aminoindan is the
R-enantiomer thereof.
14. A process according to any one of claims 1 to 12, wherein the l-aminomdan is
the racemate, and further comprising treating the racemic N-propargyl 1-
indanamine produced in step (c) with a suitable resolving agent to produce (R)-N-
propargyl l-indanamine.
15. A process according to claim 14, wherein the resolving agent is L-tartaric acid.
16. A process for resolving racemic N-allyl-i-aminoindan, comprising treating the
the racemic N-allyl-i-aminoindan with a chiral resolving agent selected from the
corresponding chiral acid of tartaric acid, dipara toluyl tartaric acid, camphorsulphonic acid, mandelic acid and the like.
17. A process for resolving racemic N-(2,3 dihalo propyl)-1-aminoindan,
comprising treating the N-(2,3 dihalo propyl)-1-aminoindan with a chiral resolving
agent selected from the corresponding chiral acid of tartaric acid, dipara toluyl tartaric acid, camphorsulphonic acid, mandelic acid and the like.

16
18. N-C2,3 dihalo propyl)-1-aminoindan or its enantiomer thereof.
19. N-(2,3 dihalo propyl)-1-aminoindan substantially as herein described with reference to the examples.
20. A process for preparing Rasagiline substantially as herein described with
reference to the examples.