Microwave-assisted synthesis of (±) -mandelic acid- d 5, optical resolution, and absolute configuration determination

Abstract

An efficient microwave-assisted synthesis of (±) -mandelic acid- d 5 was developed. The racemic mixture was resolved by diastereomeric salt formation using 1-phenylethylamine enantiomers as resolving agents. At each step, the resolution process was checked by determining mandelic acid- d 5 enantiomer ee values directly on fractional crystallized diastereomeric salts by chiral capillary electrophoresis analysis. Highly enriched (-)- and (+)-mandelic acid- d 5 (95 and 90 ee, resp.) were obtained and their absolute configurationsR and S, respectivelywere determined by correlation of the (-)-mandelic acid- d 5 circular dichroism spectrum to the (R)-mandelic acid one. © 2013 Claudio Bruno et al.