Development of a Manufacturing Process for Zatosetron Maleate

Zatosetron maleate is a potent, selective 5-hydroxytryptamine receptor antagonist. In anticipation of commercialization, a manufacturing synthesis of zatosetron from tropinone and 5-chlorosalicylic acid was developed. Development efforts focused on addressing several key issues including the supply and quality of the critical raw material tropinone, improvements in the stereoselective formation of 3-endo-tropanamine, and the compatibility with existing manufacturing capabilities of process requirements for the Claisen rearrangement used to produce a crucial benzofuran intermediate. The results of these studies and an improved route to zatosetron maleate are described.