CLAIMS
1. A method for preparation of 1 -(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl}amino)-propyl]-2,3-dihydro-lH-indole-7-carboxamide of the structural formula (VIII):
comprising converting l-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-
trifluoroethoxy)phenoxy] ethyl} amino)propyl]-2,3-dihydro-1 H-indole-7-carbonitrile of the structural formula (V)
V
to a carboxylate salt, subsequently neutralizing and hydrolyzing to yield 1 -(3-
hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2- trifluoroethoxy)phenoxy]ethyl}amino)-
propyl]-2,3-dihydro-lH-indole-7-carboxamide of the structural formula (VIII).
2. A method for preparation as claimed in claim 1, comprises of 1 -(3-hydroxypropyl)-5-[(2R)-2-({ 2- [2-(2,2,2- trifluoroethoxy)phenoxy] ethyl} amino)-propyl] -2,3-dihydro-lH-indole-7-carboxamide of the structural formula (VIII):

mixing l-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl} amino)propyl]-2,3-dihydro-lH-indole-7-carbonitrile of the structural formula (V):
V with N-acetyl glutamic acid to yield l-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy] ethyl} amino)propyl]-2,3-dihydro-1 H-indole-7-carbonitrile N-acetyl mono glutamate of the structural formula (VI):,
VI O
subsequently neutralizing the glutamate and hydrolyzing to yield 1 -(3-
hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2- trifluoroethoxy)phenoxy]ethyl}amino)-
propyl]-2,3-dihydro-lH-indole-7-carboxamide of the structural formula (VIII).
3. A method for preparation as claimed in claim 1, which comprises neutralising the 1-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-
trifluoroethoxy)phenoxy]ethyl}amino)propyl]-2,3-dihydro-lH-indole-7-carbonitrile N-acetyl mono glutamate to l-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-

trifluoroethoxy)phenoxy]ethyl}amino)propyl]-2,3-dihydro-lH-indole-7-carbonitrile of the structural formula (VII).
4. A one pot process for the preparation of l-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl}amino)propyl]-2,3-dihydro-lH-indole-7-carboxamide of the structural formula (VIII) as crystalline gamma form comprising of:

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/-Y^---^r^H^'"'"''»>^"
»-v.r

\ 60NH3 Cfs
£)H yj^
a) Reacting l-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy] ethyl}amino)propyl]-2,3-dihydro-lH-indole-7-carbonitrile (VII) with an alkali solution
in presence of an oxidizing agent at lower temperature
b) Quenching the reaction mass of step a) with sodium sulphite solution
c) Diluting the reaction mass of step b) with a halogenated aliphatic hydrocarbon solvent and removal of aqueous layer.
d) Diluting the organic layer of step c) with an aromatic hydrocarbon solvent and removal of halogenated aliphatic hydrocarbon.
e) Cooling the solution of step d) to room temperature

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f) Addition of a CI to C6 aliphatic ether to the aromatic hydrocarbon solution of step e)
g) Filtering silodosin as gamma crystalline form.
5. A one pot process for the preparation of l-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl}amino)propyl]-2,3-dihydro-lH-indole-7-carboxamide of the structural formula (VIII) as crystalline gamma form as claimed in claim 4 comprising of:
a) Reacting l-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy] ethyl}amino)propyl]-2,3-dihydro-lH-indole-7-carbonitrile (VII) with aqueous sodium hydroxide solution
in presence of hydrogen peroxide at 5 to 10°C
b) Quenching the reaction mass of step a) with sodium sulphite solution
c) Diluting the reaction mass of step b) with dichloromethane and removal of aqueous layer
d) Diluting the organic layer of step c) with toluene and removal of dichloromethane
e) Cooling the solution of step d) to room temperature
f) Addition of a methyl tertiary butyl ether to the solution of step e)
g) Filtering silodosin as gamma crystalline form.

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6. A process for preparation of Gamma crystalline form of silodosin comprising dissolving silodosin in a mixture of C-1 to C-6 alcohol and an aromatic hydrocarbon optionally at an elevated temperature followed by addition of an anti-solvent preferably an ether at lower temperature followed by stirring and filtration
7. A method of preparation as claimed in claim 6 wherein C-1 to C-6 alcohol is isopropanol, methanol, ethanol and propanol
8. A method of preparation as claimed in claim 7 wherein C-1 to C-6 alcohol is
isopropanol
9. A method of preparation as claimed in claim 6 wherein an aromatic hydrocarbon hydrocarbon solvent is toluene, benzene, ethyl benzene and xylene
10. A method of preparation as claimed in claim 9 wherein hydrocarbon solvent is toluene
11. A method of preparation as claimed in claim 6 wherein ether is methyl tertiary butyl ether, diethyl ether, methyl ethyl ether and methyl phenyl ether
12. A method of preparation as claimed in claim 11 wherein ether is methyl tertiary butyl ether
13. A process for the preparation of gamma crystalline form of silodosin according to claim 6, wherein residual toluene content is less than 890 ppm as obtained by the process comprising the steps of;

a) Slurrying gamma crystalline form of silodosin in an ether, preferably methyl tertiary butyl ether at ambient temperature or at lower temperature followed by stirring and filtration
b) Drying the resulting compound
e) Isolating polymorphic form gamma of silodosin having toluene content less than 890 ppm.
14. l-(3-hydroxy propyl)-5-[(2R)-2-({2-(2,2,2-trifluoroethoxy)phenoxy]ethyl}amino)-propyl]2,3-dihydro-lH-indole-7-carbonitrile N-acetyl mono glutamate.
15. A crystalline form of l-(3-hydroxy propyl)-5-[(2R)-2-({2-(2,2,2-trifluoroethoxy)phenoxy]ethyl}amino)-propyl]2,3-dihydro-lH-indole-7-carbonitrile N-acetyl mono glutamate characterized by a XRD pattern with strong peaks at 5.38, 6.69, 8.55, 12.0, 15.08, 16.38, 17.35, 18.80, 19.42, 20.12, 21.17, 21.87, 22.18, 23.7, 24.87, 25.26, 26.19, 26.98, 27.51, 29.10 ± 0.2 degrees 20.

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16. A crystalline form of l-(3-hydroxy propyl)-5-[(2R)-2-({2-(2,2,2-trifluoroethoxy)phenoxy]ethyl}amino)-propyl]2,3-dihydro-lH-indole-7-carbonitrile N-acetyl mono glutamate as claimed in claim 15 characterized by a XRD pattern as depicted in Figure 1
17. A one pot process for the preparation of l-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl}amino)propyl]-2,3-dihydro-lH-indole-7-carboxamide of the structural formula (VIII) as crystalline beta form comprising of:
a) Reacting l-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy] ethyl}amino)propyl]-2,3-dihydro-lH-indole-7-carbonitrile (VII) with aqueous alkali solution
in presence of an oxidizing agent at lower temperature
b) Quenching the reaction mass with sodium sulphite solution
c) Diluting the reaction mass with a halogenated aliphatic hydrocarbon solvent and removal of aqueous layer.
d) Diluting the organic layer with an aromatic hydrocarbon solvent and removal of halogenated aliphatic hydrocarbon.
e) Addition of a CI to C6 aliphatic ether to the aromatic hydrocarbon solution at elevated temperature.
f) Partially cooling the solution of step e), seeding with crystalline beta silodosin.

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g) Slowly cooling to room temperature and filtering silodosin as beta crystalline form. 18. A one pot process for the preparation of l-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl}amino)propyl]-2,3-dihydro-lH-indole-7-carboxamide of the structural formula (VIII) as crystalline beta form as claimed in claim 17, comprising of:
a) Reacting l-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy] ethyl}amino)propyl]-2,3-dihydro-lH-indole-7-carbonitrile (VII) with aqueous sodium hydroxide solution
in presence of hydrogen peroxide at 5 to 10°C
b) Quenching the reaction mass with sodium sulphite solution
c) Diluting the reaction mass with dichloromethane and removal of aqueous layer
d) Diluting the organic layer with toluene and removal of dichloromethane
e) Addition of methyl tertiary butyl ether to the organic layer of step d) at 75 to 80°C
f) Partially cooling the solution of step e) to 65 to 70°C, seeding with crystalline beta silodosin
g) Slowly cooling to room temperature and filtering silodosin as beta crystalline form.
19. A process for the preparation of silodosin crystalline beta form from silodosin crystalline gamma form comprising steps of:

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a) Dissolving the silodosin crystalline gamma form in an aromatic hydrocarbon solvent at an elevated temperature
b) Addition of a CI to C6 aliphatic ether solvent to the aromatic hydrocarbon solution of step a) at elevated temperature
c) Partially cooling the solution of step b), seeding with crystalline beta silodosin
d) Slowly cooling to room temperature and filtering silodosin as beta crystalline form.
20. A process for the preparation of silodosin crystalline beta form from silodosin crystalline gamma form as claimed in claim 19, comprising steps of:
a) Dissolving silodosin crystalline gamma form in toluene at 75°C
b) Addition of a methyl tertiary butyl ether to solution of step a) at 75°C.
c) Partially cooling the solution of step b) to 60°C, seeding with crystalline beta silodosin.
d) Slowly cooling to room temperature and filtering silodosin as beta crystalline form.