An Improved Process for the Preparation of Highly Pure Solifenacin Succinate via Resolution through Diastereomeric Crystallisation

An improved process for the preparation of solifenacin succinate (1) involving resolution through diastereomeric crystallization is described. (1S)-IQL derivative (5) is esterified to form (1S)-ethoxycarbonyl IQL derivative (6) which is condensed with (RS)-3-quinuclidinol (7) to form a solifenacin diastereomeric mixture (8); this is subjected to resolution through diastereomeric crystallization to produce solifenacin succinate (1), which is used for the treatment of an overactive bladder.