Field of the Invention:
The present invention relates to novel salts of 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine compound of general formula-1 and their use. 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine is one of the intermediate in the preparation of l-[[[3-[2-(dimethylamino)ethyl]-lH-indol-5-yl] methyl]sulfonyl] pyrrolidine, which is commonly known as "almotriptan".
Almotriptan binds with high affinity to 5-HTID, 5-HTIB and 5-HTIF receptors. The malate salt of almotriptan is indicated for the acute treatment of migraine with or without aura in adults. Almotriptan malate is commercially available under the brand name of AXERT® and ALMOGRAN®.
Background of the Invention:
Almotriptan and its pharmaceutically acceptable salts as well as process for their preparation are disclosed in US 5565447 and ES 2084560. ES 2084560 describes a process for the preparation of almotriptan based on Fisher indole synthesis using a phenyl hydrazine and 4-chloro-butyraldehyde diethyl acetal to provide l-[[3-(2-aminoethyl)-5-indolyl]methanesulfonyl]pyrrolidine, which is further treated with aqueous formaldehyde and then sodium borohydride to provide almotriptan. Thus obtained almotriptan is converted into DL-malate salt. This process provides almotriptan in poor yields. Moreover it was observed that the purity of the intermediates like 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine (herein after referred as "amino indole") and final products are not adequate and are having approximately 75-80% of purity by HPLC. Specifically the amino indole intermediate obtained as a residue and is not stable at ambient temperature.
WO 2006/129190 describes a process for the preparation almotriptan malate. The disclosed process comprises of treating 5-(l-pyrrolidinyl-sulfonylmethyl)-lH-indole-3-ethanol with methane sulfonyl chloride and then dimethylamine followed by column purification of almotriptan. Moreover the preparation of 5-(l-pyrrolidinyI-sulfonylmethyl)-lH-indole-3-ethanol involves the usage of n-butyl lithium. As this

process involves the usage of reagents like n-butyl lithium and purification techniques like column chromatography, they are commercially not recommendable.
WO 2008/151584 describes a process for the preparation of almotriptan malate, which involves the conversion of 4-(pyrrolidinylsulfonylmethyl) phenyl hydrazine 4-chloro-l-hydroxybutane-l-sulfonate or 4-(pyrrodinylsulfonylmethyl) phenyl hydrazine toluene sulfonate into crude almotriptan and then converting the crude almotriptan into its fiimarate salt. Thus formed almotriptan fumarate is converted into crystalline almotriptan free base. The crystalline free base was treated with malic acid to provide almotriptan malate. As per this reported process, almotriptan fimiarate obtained is in very poor purity of about 92% and the same has been utilized to convert back to almotriptan free base. The said process involves the isolation of almotriptan fi«e base in a crystalline form to get the almotriptan malate with the required purity but the process is time consuming.
In general, the reported processes for the preparation of almotriptan or its salts proceed through the amino indole intermediate in the form of crude with very less purity of about 75-80%. The said intermediate was not stable at ambient temperature and usage of same in further steps leads the final compound contaminated with high level of impurities. When the present inventors working to resolve these problems, the present inventors surprisingly found that the salts of amino indole intermediate make it highly stable at ambient condition and having the purity of greater than 97% by HPLC and does not require any specific equipment and temperature for storsge.
It has been observed that the almotriptan malate prepared as per the reported processes containing amino indole and mono methyl compounds as a major impurities in the range of 0.5 to 1% by HPLC along with other known and unknown impurities in the limit of more than 0.1% by HPLC. Hence it is necessary to have a process for the purification of almotriptan malate to eliminate the above said impurities.
The main aspect of the present invention is to provide a stable amino indole salts, its use and also a process for the purification of almotriptan malate.

Brief Description of the Invention:
The first aspect of the present invention is to provide novel salts of 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine compound of general formula-l and their use in the preparation of highly pure almotriptan and its pharmaceutically acceptable salts.
The second aspect of the present invention is to provide a process for the preparation of novel salts compound of general formula-l, which comprises of reacting the 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine with a suitable acid in a suitable solvent to provide the corresponding salt compound of formula-l.
The third aspect of the present invention is to provide a process for the preparation of highly pure almotriptan compound of formula-2 through the novel salt compound of formula-l, which comprises of the following steps;
a) treating the l-(4-hydrazinylbenyzlsulfonyl)pyrroUdine or its salt compound of formula-3 with protected derivative of 4-chlorobutraldehyde compound of formula-4 in presence of disodium hydrogen phosphate and acid in a suitable solvent, followed by treating the obtained compound with a suitable acid to provide the corresponding salt of 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine compounds of general formula-l,
b) reacting the salt compounds of general formula-l with a suitable base in a suitable solvent to provide free base of compound of formula-l, which on in-situ reaction with formalin in presence of sodiumborohydride in aqueous sodium hydroxide, in a suitable solvent to provide almotriptan, which on in-situ treatment with malic acid in a suitable solvent provides almotriptan malate compoimd of formula-2a,
c) optionally purifying the obtained almotriptan malate compoimd of formula-2a.
The fourth aspect of the present invention is to provide novel crystalline form of 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine oxalate compound of formula-la and process for its preparation. The novel crystalline form of the present invention is characterized by its powder X-ray diffractogram.

The fifth aspect of the present invention is to provide an improved process for the purification of almotriptan malate compound of fonnula-2a, which comprises of treating almotriptan malate compound of fomiula-2aa with suitable base in a suitable solvent to provide almotriptan, which on in-situ treatment with malic acid in a suitable solvent provides almotriptan malate compound of formula-2a.
Brief Description of the Drawings:
Figure-1: Illustrates the PXRD of crystalline compound of formula-la
Detailed Description of the Invention:
As used herein the term "alcoholic solvent" refers to methanol, ethanol, n-propanol, isopropnol, n-butanol and isobutanol; "chloro solvent" refers to methylene chloride, chloroform and ethylene dichloride; "ketone solvent" refers to acetone, methyl ethyl ketone, methyl isobutyl ketone; "hydrocarbon solvent" refers to toluene, hexane, heptane and cyclohexane; "nitrile solvent" refers to acetonitrile; "ester solvent" refers to ethyl acetate, methyl acetate and isopropyl acetate; "ether solvent" refers to tetrahydrofiiran, diethyl ether and methyl tert-butyl ether; "polar solvent" refers to water.
As used herein the term "suitable base" refers to the bases selected from alkali metal hydroxide like sodium hydroxide, potassium hydroxide; alkali metal carbonate like sodium carbonates, potassium carbonate and bicarbonates like sodium bicarbonate, potassium bicarbonate; ammonia or their aqueous solution.
The present invention relates to novel salts of 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine compound of general formula-1 and their use in the preparation of highly pure almotriptan compound of fonnula-2.
Accordingly the first aspect of the present invention provides novel salts of 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine compounds of general formula-1


wherein "Acid" is an acid group which is capable of forming acid addition salt with 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine and is selected from group comprising of oxalic acid, succinic acid, fumaric acid, malonic acid, malic acid, maleic acid, d-tartaric acid, 1-tartaric acid, dl-tartaric acid, citric acid, methanesulfonic acid, paratoluene sulfonic acid, acetic acid, sulfuric acid, phosphoric acid or hydrobromic acid and hydrochloric acid.
The novel salts of 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl) ethanamine compound of general formula-1 of the present invention is highly stable and having high purity when compared to the free base obtained as per the prior art. It also used to prepare pure 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine free base, almotriptan and its pharmaceutically acceptable salts thereof
The second aspect of the present invention provides a process for the preparation of novel salts compound of general formula-1, which comprises of treating the 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine with a suitable acid as defined above, in a suitable solvent selected from alcohol solvents, ester solvents, hydrocarbon solvent, ketone solvents, nitrile solvents, chloro solvents or mixtures thereof, to provide the corresponding salt compound of general formula-1.
The third aspect of the present invention provides a process for the preparation of highly pure almotriptan compound of formula-2 through novel salts compound of general formula-1, which comprises of the following steps;
a) reacting the l-(4-hydrazinylbenzylsulfonyl)pyrrolidine hydrochloride compound of formula-3
with 4-chloro butyraldehyde diethyl acetal compound of formula-4


in presence of disodium hydrogenphosphate and a suitable acid in a suitable solvent followed by treating the obtained product with suitable acid in a suitable polar or alcohol solvent to provide the corresponding acid addition salt of 2-(5-((pyrrolidin-l-yl-sulfonyl)methyl)-lH-indol-3-yl)ethanamine compound of general formula-1

b) treating the salt compounds of general formula-1 with a suitable base in a suitable solvent to provide 2-(5-((pyrrolidin-l-yl-sulfonyl)methyl)-lH-mdol-3-yl)ethanamine, which on in-situ reaction with formalin in presence of sodiumborohydride in aqueous sodium hydroxide, in a suitable solvent to provide ahnotriptan, followed on in-situ treatment with malic acid in a suitable solvent provides corresponding almotriptan malate compound of formula-2a,

In a preferred embodiment, improved process for the preparation of highly pure almotriptan malate compoimd of formula-2a comprises of the following steps; a) reacting the l-(4-hydrazinylbenzylsulfonyl)pyrrolidine hydrochloride compound of formula-3

with 4-chloro butyraldehyde diethyl acetal compound of formula-4


in presence of disodium hydrogen phosphate, aqueous hydrochloric acid in methanol provides 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl) ethanamme, which on-insitu treatment with oxalic acid in water provides the 2-(5-((pyrrolidin-l-yl-sulfonyl)methyl)-lH-indol-3-yl)ethanamine oxalate compound of formula-la

b) treating oxalate salt compound of formula-la with aqueous ammonia and extracting the obtained 2-(5-((pyrrolidin-l-yl-sulfonyl)methyl)-lH-indol-3-yl)ethanamine into methylene chloride, which on in-situ reaction with formalin in presence of sodium borohydride in aqueous sodium hydroxide, in methanol provides almotriptan, followed by treating it in-situ with malic acid in a methanol provides almotriptan malate compound of formula-2a.
The fourth aspect of the present invention provides novel crystallme form of 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine oxalate salt represented by the following structural formula-la

The novel crystalline oxalate salt of the present invention is characterized by its powder X-ray diffractogram having peaks at about 7.97, 14.06, 16.52,16.85,17.28,18.26,19.45, 19.94,21.16,22.74,24.52,25.13,26.29,30.08,33.41,36.28 and 39.91 ± 0.2 degrees 26. The novel crystalline form of formula-la of the present invention is used to prepare highly pure almotriptan or its pharmaceutically acceptable salts.
The fifth aspect of the present invention provides a process for the purification of almotriptan malate compound of fonnula-2a, which comprises of treating the almotritpan malate with a suitable base selected fi-om alkali metal hydroxides like sodium hydroxide, potassium hydroxide; alkali metal carbonates like sodium carbonate, potassium carbonate

and bicarbonates like sodium bicarbonate, potassium bicarbonate; ammonia or their aqueous solution, in a suitable solvent selected from ester solvents, hydrocarbon solvents, chloro solvents or mixtures thereof, to provide aUnotriptan, which on in-situ treatment with malic acid in a suitable solvent selected from alcohols, ketones, nitirle or polar solvents or mixtures thereof, to provide highly pure ahnotriptan malate compound of formula-2a.
A process for the purification of almotriptan malate compound of formula-2a is provided to reduce the amount of impurities particularly amino indole impurity and monomethyl impurity present to the level of 0.5-1% by HPLC along with other impurities to the concentration of around 0.05% to levels of non detection. The said purification process comprises of the following steps;
a) treating the almotritpan malate with a suitable base in a suitable solvent selected from ester solvents, hydrocarbon solvents and chloro solvents,
b) separating the organic and aqueous layer,
c) distilling off the solvent from organic layer under reduced pressure,
d) dissolving the obtained residue in a suitable solvent or mixtures thereof at reflux temperature,
e) subjecting the reaction mixture to carbon treatment,
f) filtering the reaction mixture through hyflo,
g) adding malic acid or its solution in a suitable solvent to the filtrate,
h) cooling the reaction mixture,
i) filtering the solid and washing with a suitable solvent, j) drying the solid to get the highly pure almotriptan malate.
In a preferred embodiment, process for the purification of almotriptan malate compound of formula-2a comprises of the following steps,
a) treating the almotritpan malate in ethylacetate with aqueous ammonia,
b) separating the organic and aqueous layer,
c) distilling off the ethylacetate from organic layer under reduced pressure,
d) dissolving the obtained residue in a mixture of isopropyl alcohol and methanol at reflux temperature.

e) subjecting the reaction mixture to carbon treatment,
f) filtering the reaction mixture through hyflo,
g) adding malic acid solution in a mixture of isopropyl alcohol and methanol to the filtrate,
h) cooling the reaction mixture and stirring,
i) filtering the solid and washing with a mixture of isopropyl alcohol and methanol,
j) drying the solid to get the highly pure almotriptan malate.
The following impurities are the possible impurities as firee bases or their salts which are formed during the process for the preparation of almotriptan and its pharmaceutically acceptable salts.

One of the major focus of the invention was to control the impurities formed in the process to as minimum levels as possible in the final pharma. This is ensured by purification process involving the conversion of almotriptan malate into fi-ee base by treating it with base followed by extracting it with a suitable solvent and then subsequently subjecting it to carbon treatment and treating it mih malic acid to convert it into almotriptan malate with high purity. The major impurities formed in substantial

quantities were the amino indole impurity and mono methyl impurity which were purified from the levels of 0.5 to 1 % each to the level of non-detection and 0.02% respectively. All the above impurities are well controlled in the process to the levels of 2.0% which were reduced to the levels of 0.2% after purification. The each individual impurities are reduced to the levels of 0.1%, preferably to the level of 0.05% by the purification method.
As used herein the term "highly pure" refers to the compound with purity greater than 98 % by HPLC, preferably greater than 99 % by HPLC and more preferably greater than 99.50% by HPLC.
XRD analysis of 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl) ethanamine salts were carried out using SIEMENS/D-5000 X-Ray dif&actometer using Cu, Ka radiation of wavelength 1.54 A° and continuous scan speed of 0.045°/min.
The related substance of almotriptan malate and salts of 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl) ethanamine were analyzed by HPLC using the following conditions: Column: Symmetry CI8 250 x 4.6 mm, 5.0 mi; Flow rate: 1.6 ml/min; wavelength: 228 nm ; Temperature: 35°C; Load: 20 il; Run time: 50 min; Elution: gradient; and using mixture of buffer and acetonitrile as a diluent and mobile phase. The buffer is prepared by a mixture of triethylamine and water.

The process described in the present invention was demonstrated in examples illustrated below. These examples are provided as illustration only and therefore should not be construed as limitation of the scope of the invention. Examples:
Example-1: Preparation of 2(5-((pyrroIidin-l-ylsuIfonyl)methyl)-lH-mdol-3-yl) ethanamine oxalate compound of formula-la:
A mixture of 4-chlorobutaraldehyde diethyl acetal (120 grams), hydrochloric acid (48 ml) and water (1050 ml) was stirred at 20-25°C. This mixture was added to a mixture of l-(4-hydrazinylbenzylsulfonyl)pyrrolidine hydrochloride (150 grams), water (450 ml) and methanol (1.2 1) at 10-15°C and stirred. The solid obtained was filtered and washed with water. Methanol followed by disodium hydrogen phosphate solution ((73 grams in 600 ml of water) was added to the solid and the acidified the reaction mixture with aqueous hydrochloric acid. The reaction mixture was heated to reflux and stirred at reflux. After completion of the reaction, methanol was distilled off completely under reduced pressure. The residue was cooled, water (1.5 L) and methylene chloride (450 ml) were added to it and basified with sodium carbonate solution. The aqueous layer was separated and expelled with nitrogen. Oxalic acid (51.8 grams) was added to it and stirred at 25-30°C. The reaction mixture was cooled to 5-10**C and stirred. The obtained solid was filtered, washed with water and dried to get the title compound. The PXRD of crystalline form of the obtained oxalate salt is represented in figure-1. Yield: 95 grams M.R: 128-133°C; Purity by HPLC: 98.95%
Example-2: Preparation of almotriptan malate:
A mixture of 2(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl) ethanamine oxalate compound of formula-la (50 grams), water (500 ml) and methylene chloride (250 ml) was stirred and basified it with aqueous ammonia then stirred. The organic layer was separated and solvent fi-om it was distilled off completely under reduced pressure. The residue was dissolved in methanol (770 ml) and cooled to 5-1 SC. Sodium borohydride (24 grams) in aqueous sodium hydroxide (0.77 grams in 335 ml of water) and formalin solution (161.4 ml) in methanol (161.4 ml) was added to the reaction mixture lotwise at

5-15°C and stirred. After completion of the reaction, quenched it with aqueous hydrochloric acid and stirred. The reaction mixture was basified with sodium bicarbonate solution and methanol was distilled off completely under reduced pressure. The reaction mixture was washed with ethylacetate and then basified with potassium carbonate. The reaction mixture was extracted into ethylacetate and then washed it with sodium chloride solution and then ethylacetate was distilled off completely under reduced pressure. Methanol was added to the obtained residue followed by malic acid (17.9 grams) and stirred for 45 minutes. The reaction mixture was heated to reflux and stirred. The reaction mixture was cooled to Q-5°C and stirred for an hour. The solid obtained was filtered and washed with methanol. The obtained wet solid was recrystallized fi-om methanol to get the title compound. Yield: 32 grams Purity by HPLC: 99.02 %; 0.06% (amino indole impurity); 0.13% (monomethylimpurity)
Example-3: Purification of almotriptan malate:
Almotriptan malate (having purity of 98.57% and containing 0.59% of aminoindole impurity & 0.40 % of monomethylimpurity) (100 grams) was dissolved in water (IL), added ethyl acetate (600 ml) and basified the reaction mixture with aqueous ammonia. The reaction mixture was stirred for 30 mmutes at 25-30°C and the ethyl acetate layer was separated. Aqueous layer was extracted with ethyl acetate and then total ethyl acetate layer was distilled off completely under reduced pressure at below 60°C. The residue was dissolved in methanol (200 ml) and subjected to carbon treatment, then filtered through hyflow. Malic acid (37.2 grams) was added to the filtrate and heated to reflux temperature then stirred for 30 minutes at reflux. The reaction mixture was cooled to 25"30°C and stirred for 2 hours. Filtered the solid, washed with methanol and dried to get the pure titie compound. Yield: 77 grams Purity by HPLC: 99.84%; 0.02% (amino indole impurity); 0.06% (monomethylimpurity)
£xample-4: Purification of almotriptan malate:
Almotriptan malate (having purity of 98.39% and containing 0.20% of aminoindole impurity & 0.60 % of monomethylimpurity) (55 grams) was dissolved in

water (550 ml), added ethyl acetate (330 ml) and basified the reaction mixture with aqueous ammonia. The reaction mixture was stirred for 30 minute at 25-30''C and the ethyl acetate layer was separated. Aqueous layer was extracted with ethyl acetate and then total ethyl acetate layer was distilled off under reduced pressure at below 60°C. The residue was dissolved in a mixture of isopropylalcohol and methanol in the ratio of 6:4 (55 ml) and subjected to carbon treatment, then filtered through hyflow. Malic acid (9 grams) in a mixture of IPA:MeOH (220 ml) was added and heated to reflux temperature then stirred for 30 minutes at reflux. The reaction mixture was cooled to 25-30°C and stirred for 2 hours. Filtered the solid, washed with a mixture of isopropylalcohol and methanol and dried to get the pure title compound. Yield: 49 grams Purity by HPLC: 99.87%; 0.01% (amino indole impurity); 0.04% (monomethylimpurity)
Example-S: Preparation of 2(5-((pyrrolidin-l-ylsulfonyl)methyI)-lH-indoI-3-yl) ethanamine crude:
A mixture of 4-chlorobutaraldehyde diethyl acetal (120 grams), hydrochloric acid (48 ml) and water (1050 ml) was stirred at 20-25°C. This mixture was added to a mixture of l-(4-hydrazinylbenzylsulfonyl)pyrrolidine hydrochloride (150 grams), water (450 ml) and methanol (1.2 1) at 10-15°C and stirred. The solid obtained was filtered and washed with water. Methanol followed by disodium hydrogen phosphate solution ((73 grams in 600 ml of water) was added to the solid and the acidified the reaction mixture with aqueous hydrochloric acid. The reaction mixture was heated to reflux and stirred at reflux. After completion of the reaction, methanol was distilled off completely under reduced pressure. The residue was cooled, water (1.5 L) and methylene chloride (450 ml) was added to it and basified with sodium carbonate solution. The aqueous layer was separated, basified it with sodium carbonate and then product was extracted into methylene chloride. The methylene chloride layer was dried over sodium sulphate and distilled off completely under reduced pressure to get the title compound. Yield: 90 grams

£xampIe-6: Preparation of 2(5-((pyrrolidin-l-yIsulfonyl)methyI)-lH-indol-3-yI) ethanamine succinate:
A mixture of 2(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl) ethanamine crude prepared as per example-5 (2 grams) and ethanol (10 ml) was heated to 50-55°C and stirred. Succinic acid (0.77 grams) was added to the reaction mixture and stirred for an hour at 50-55°C. The reaction mixture was cooled to 25-30°C and stirred. The obtained solid was filtered, washed with ethanol and then dried to get the title compound. Yield: 2.2 grams M.R: 163-167°C; Purity by HPLC: 99.10%
Example-?: Preparation of 2(5-((pyrrolidin-l-yl8ulfonyI)methyl)-lH-lndol-3-yl) ethanamine malate:
A mixture of 2(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl) ethanamine crude prepared as per example-5 (2 grams) and ethanol (10 ml) was heated to SO-SSC and stirred. Malic acid (0.9 grams) was added to the reaction mixture and stirred for an hour at 50-55°C. The reaction mixture was cooled to 25-30°C and stirred. The obtained solid was filtered, washed with ethanol and then dried to get the title compound. Yield: 1.9 grams M.R: 167-171°C; Purity by HPLC: 98.87%
Example-S: Preparation of 2(5-((pyrrolidin-l-ylsuIfonyI)methyI)-lH-indoI-3-yl) ethanamine tartarate:
A mixture of 2(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl) ethanamine crude prepared as per example-5 (2 grams) and ethanol (10 ml) was heated to 50-55°C and stirred. Tartaric acid (0.97 grams) was added to the reaction mixture and stirred for an hour at 50-55°C. The reaction mixture was cooled to 25-30°C and stirred. The obtained solid was filtered, washed with ethanol and then dried to get the title compound. Yield: 2.3 grams M.R: 156-158°C; Purity by HPLC: 98.10%

£xample-9: Preparation of 2(5-((pyrrolidiii-l-ylsuIfoiiyI)methyl)-lH-indol-3-yl) ethanamine fumarate:
A mixture of 2(5-((pyrrolidm-l-ylsulfonyl)methyl)-lH-indol-3-yl) ethanamine crude prepared as per example-5 (2 grams) and ethanol (10 ml) was heated to 50-55°C and stirred. Fumaric acid (0.76 grams) was added to the reaction mixture and stirred for an hour at 50-55°C. The reaction mixture was cooled to 25-30°C and stirred. The obtained solid was filtered, washed with ethanol and then dried to get the title compound. Yield: 1.5 grams M.R: 189-191°C; Purity by HPLC: 98.17%

We Claim:
1. Novel salts of 2-(5-((pyrroUdin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanainine
represented by the following general formula-1

wherein "Acid" is an acid group which is capable of forming acid addition salt with 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine and is selected from group comprising of oxalic acid, succinic acid, fumaric acid, malonic acid, malic acid, maleic acid, d-tartaric acid, 1-tartaric acid, dl-tartaric acid, citric acid, methanesulfonic acid, paratoluene sulfonic acid, acetic acid, sulfuric acid, phosphoric acid, hydrobromic acid and hydrochloric acid.
2. The process for the preparation of novel salts compound of general fdrmula-1 claimed in claim 1, which comprises of treating the 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine with a suitable acid as defined above in a suitable solvent selected from alcohol solvents, ester solvents, hydrocarbon solvent, ketone solvents, nitrile solvents, cWoro solvents or mixtures thereof, provides the corresponding salt compound of general formula-1.
3. Use of novel salts of 2-(5-((pyrroUdin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine compounds of general formula-1 as claimed in claim 1, in the preparation of highly pure 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine, almotriptan or its pharmaceutically acceptable salts.
4. A process for the preparation of highly pure ahnotriptan malate compound of formula-2a,


which comprises of the following steps;
a) treating the acid addition salt of 2-(5-((pyrrolidin-1 -yl-sulfonyl)methyl)-1 H-indol-
3-yl)ethanainine compound of general formula-1

with a suitable base in a suitable solvent to provide 2-(5-((pyrrolidin-l-yl-sulfonyl)methyl)-lH-indol-3-yl)ethanarame, which on in-situ reaction with formalin in presence of sodiumborohydride in aqueous sodium hydroxide, in a suitable solvent provides almotriptan, which on in-situ treatment with malic acid in a suitable solvent provides corresponding almotriptan malate compound of formula-2a.
5. An improved process for the preparation of highly pure almotriptan malate compound of formula-2a through novel salts compound of general formula-1, which comprises of the following steps;
b) reacting the l-(4-hydrazinylbenzylsulfonyl)pyrrolidine hydrochloride compound
offormula-3

with 4-chloro butyraldehyde diethyl acetal compound of fonnula-4


in presence of disodium hydrogen phosphate and acid in a suitable solvent followed by treating the obtained product with a suitable acid in a suitable solvent like alcohols or polar solvent or mixtures thereof, provides the corresponding acid addition salt of 2-(5-((pyrrolidin-l-yl-sulfonyl)methyl)-lH-indol-3-yl)ethanamine compound of general formula-1

c) treating the salt compounds of general formula-1 with a suitable base in a suitable solvent to provide 2-(5-((pyrrolidin-l-yl-sulfonyl)methyl)-lH-indol-3-yl)ethanamine, which on in-situ reaction with formalin in presence of sodiumborohydride in aqueous sodium hydroxide, in a suitable solvent provides almotriptan, which on in-situ treatment with malic acid in a suitable solvent provides corresponding almotriptan malate compound of formula-2a,

6. Crystalline form of 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine oxalate salt characterized by its powder X-ray dififractogram having peaks at about 7.97, 14.06, 16.52, 16.85, 17.28, 18.26, 19.45, 19.94, 21.16, 22.74, 24.52, 25.13, 26.29,30.08,33.41,36.28 and 39.91 ± 0.2 degrees 20.
7. Succinic acid, malic acid, fumaric acid and tartaric acid salts of 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine as a crystalline solid.

8. Use of crystalline salts of 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanainine as claimed in claim 6 & 7 in the preparation of highly pure 2-(5-((pyrrolidin-l-ylsulfonyl)methyl)-lH-indol-3-yl)ethanamine free base, almotriptan or its pharmaceutically acceptable salts.
9. A process for the purification of almotriptan malate compound of formula-2a, which comprises of

a) treating the almotritpan malate with a suitable base or its aqueous solution in a suitable solvent selected from ester solvents, hydrocarbon solvents and chloro solvents,
b) separating the organic and aqueous layers,
c) distilling off the solvent from organic layer under reduced pressure,
d) dissolving the obtained residue in a suitable solvent or mixtures thereof at reflux temperature,
e) subjecting the reaction mixture to carbon treatement,
f) filtering the reaction mixture through hyflo,
g) adding malic acid or its solution in a suitable solvent to the filtrate,
h) cooling the reaction mixture,
i) filtering the solid and washing with a suitable solvent, j) drying the solid to get the highly pure almotriptan malate.
10. A process for the purification of almotriptan malate compound of formula-2a, which
comprises of
a) treating the almotritpan malate in ethylacetate with aqueous ammonia,
b) separating the organic and aqueous layer,
c) distilling off the ethylacetate from organic layer under reduced pressure,
d) dissolving the obtained residue in a mixture of isopropylalcohol and methanol at reflux temperature,
e) subjecting the reaction mixture to carbon treatment,
f) filtering the reaction mixture through hyflo,
g) adding malic acid solution in a mixture of isopropyl alcohol and methanol to the filtrate.

h) cooling the reaction mixture,
i) filtering the solid and washing with a mixture of isopropyl alcohol and methanol,
j) drying the solid to get the highly pure almotriptan malate.