Microbial deracemisation of aromatic β-hydroxy acid esters

Aromatic β-hydroxy acid esters were found to undergo deracemisation using whole cells of Candida parapsilosis. The conditions for the deracemisation reaction were optimised where 75% isolated yield and >95% enantiomeric excess of the product was achieved. The effect of electron donating as well as electron withdrawing groups present in the standard substrate, ethyl 3-hydroxy 3-phenyl propionate was studied to establish the generality of the reaction. The enantiomeric excess of the product remains high (>95%) irrespective of the different substituents in the para position but substitution at the ortho position obstructs the process. Similarly, ethyl and methyl esters of the standard substrate undergo deracemisation reaction giving high ee of the product, but the benzyl ester of the standard substrate did not undergo deracemisation.