Enantioselective synthesis of (−)-(R) Silodosin by ultrasound-assisted diastereomeric crystallization

Enantioselective synthesis of clinically approved drug-Silodosin for the treatment of benign prostatic hyperplasia from the commercially available compounds 1-acetyl-5-(2-aminopropyl) indoline-7-carbonitrile A and 2-(2-(2,2,2-trifluoroethoxy)phenoxy)ethyl methanesulfonate C is explored. Key step in the synthesis is chiral resolution of intermediate 1, which was achieved by a simple diastereomeric crystallization using (S)-(+)-mandelic acid assisted by ultrasonication. The present synthetic strategy has lesser number of steps and is vastly improved the overall yield in this short route towards target compound-Silodosin.