Microwave assisted synthesis of (±)-mandelic acid-d5, optical resolution, and absolute configuration determination

An efficient microwave-assisted synthesis of(±)-mandelic acid-5 was developed. e 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-5 enantiomer ee values directly on fractional crystallized diastereomeric salts by chiral capillary electrophoresis analysis. Highly enriched (−)- and (+)-mandelic acid-5 (95% and 90% ee, resp.) were obtained and their absolute congurations— and , respectively—were determined by correlation of the (−)-mandelic acid-5 circular dichroism spectrum to the (R)-mande