| abstract |
The present invention discloses an improved process for producing darifenacin, the process comprising decarboxylating (2S,4R)-4-hydroxy-2-pyrrolidine carboxylic acid followed by in situ tosylation to give l-tosyl-3-(R)-(-)-hydroxypyrrolidine, tosylating the l-tosyl-3-(R)-(-)-hydroxypyrrolidine with methyl-p-toluenesuolphonate to give l-tosyl-3- (S)-(-)-tosyloxy pyrrolidine, reacting l-tosyl-3-(S)-(-)-tosyloxy pyrrolidine with diphenyl acetonitrile in presence of a base to give 3-(S)-(+)-(l-cyano-l,l-diphenylmethyl)-l- tosylpyrrolidine, de-protecting 3-(S)-(+)-(l-cyano-l,l-diphenylmethyl)-l- tosylpyrrolidine in the presence of phenol in acidic medium to give 3-(S)-(+)-(l-cyano- 1,1-diphenylmethyl) pyrrolidine, hydrolyzing 3-(S)-(+)-(l-cyano-l,l-diphenylmethyl) pyrrolidine followed by salt formation to obtain 3-(S)-(+)-(l-carbamoyl-l,l- diphenylmethyl)pyrrolidine.L-(+)-tartrate, condensing 3-(S)-(+)-( 1 -carbamoyl- 1,1- diphenylmethyl)pyrrolidine-L(+)-tartrate with 5-(2-bromoethyl)-2,3-dihydrobenzofuran employing a base in a solvent to give darifenacin. |