Synthesis of Silodosin

Silodosin was synthesized from 1-acetyl-5-(2-aminopropyl)-2,3-dihydro-7-cyano-1H-indole and 2-[2-(2,2,2-trifl uoroethoxy)phenoxy]ethyl methanesulfonate by condensation, resolution with L-mandelic acid to give(R)-1-acetyl-5-[2-[2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethylamino]propyl]-7-cyanoindoline, which was subjected to protection with(Boc)_2O, hydrolysis with sodium hydroxide to afford(R)-5-[2-[N-tert-butoxycarbonyl-2-[2-(2,2,2-trifl uoroethoxy)phenoxy]ethylamino]propyl]-7-cyanoindoline, followed by cyano hydrolysis, substitution with 3-bromopropyl benzoate, hydrolysis of ester group and deprotection with an overall yield of about 6.6%.