Deracemisation of aromatic β-hydroxy esters using immobilised whole cells of Candida parapsilosis ATCC 7330 and determination of absolute configuration by 1H NMR

Abstract

Deracemisation of aryl and substituted aryl β-hydroxy esters using immobilised whole cells of Candida parapsilosis ATCC 7330 yields the corresponding ( S)-enantiomer in >99% enantiomeric excess and good yield (up to 68%). The absolute configuration of ethyl 3-(2,4-dichlorophenyl)-3-hydroxy propanoate and ethyl 3-hydroxy-5-phenyl-pent-4-enoate as determined by 1H NMR using MTPA chloride was found to be ‘ S’. The chemical shifts of the methoxy groups of the two diastereomeric MTPA esters were used as diagnostic signals to determine the absolute configuration.