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

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.