Abstract

SYNTHESIS AND CHARACTERIZATION OF PHARMACEUTICALLY IMPORTANT CHIRAL INVERSION OF UNWANTED S ISOMER 3-(5-((S)-2-AMINOPROPYL)-7-CYANOINDOLIN-1-YL) PROPYL BENZOATE VIA 2, 4, 6-TRIPHENYLPYRIDINIUM SALT

Dr. Anil A. Ghanwat*, Bharat B. Kashid, Vithal M. Gugwad, Dnyanadeo J. Kesarkar

ABSTRACT

Development of more effective method for inversion of the chiral centre of the unwanted isomer by optical resolution processes to increase the overall yield. The transformation is carried out in a three step synthesis via an SN2 type reaction of the 2, 4, 6-tri-arylpyridinium salt and a subsequent nucleophilic substitution by the azide ion, which on reduced by hydrogenolysis to give an Inversion degree of 85-100%. Low stereoselectivity caused by racemization to some extent was observed for the inversion of the optically active unwanted S isomer of amine 3-(5-((S)-2-aminopropyl)-7-cyanoindolin-1-yl) propyl benzoate (Ia). However, modified reaction conditions allowed increased stereoselectivity, a more rapid and almost complete inversion of the chiral (S)-amine (Ia) to the chiral (R)-amine (Ib) of this substrate as well.

Keywords: Pyrylium salts; Pyridinium salts; Azides; Inversion of configuration.