Facile new industrial process for synthesis of teneligliptin through new intermediates and its optimization with control of impurities

Abstract

The present study is related to a commercially practicable new synthetic process for production of teneligliptin hydrobromide hydrate (1), a dipeptidyl peptidase-4 (DPP-4) inhibitor. Key strategies in the new process include preparation and isolation of new intermediates such as a better reactive nosyl derivative (3c) of l-proline methyl ester (2), its stereoselective substituted intermediate (5) with 1-(3-methyl-1-phenyl-1H-pyrazol-5-yl)piperazine (4) through SN2-type nucleophilic substitution, and isolation of carboxylic acid derivative 6 by deesterification of intermediate 5. The reaction conditions for preparation of new intermediates, and the additionally used coupling reaction for amidation and deprotection of N-Boc were optimized with control of impurities to improve the quality of drug molecule 1 with good yield. The developed synthetic strategy offers significant advantages over existing synthetic approaches, avoiding use of expensive reagents, long time consumption, and laborious procedures involving isolation of intermediates. The developed process for drug molecule 1, achieving overall yield of 37–39% over six sequential chemical transformations, enables rapid delivery of multi-kilogram quantities of the desired active pharmaceutical ingredient (API), meeting stringent purity requirements.