Lipase-catalysed enantioselective ring-opening of oxazol-5(4H)-ones coupled with partial in situ racemisation of the less reactive isomer

2-Phenyl-4-methyl-oxazol-5(4H)-one undergoes lipase-catalysed enantioselective ring-opening with butan-1-ol in di-isopropyl ether; the less reactive isomer of the oxazolone further undergoes partial in situ racemisation under the reaction conditions to afford, after quantitative conversion, butyl N-benzoylalaninate enriched in one isomer.