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