Convenient preparation of (S)-fenoprofen by biocatalysed irreversible esterification.

Immobilised lipase B from Candida antarctica catalyzes the enantioselective esterification of rac-fenoprofen, (±)-1. The use of orthoformates as alcohol donors permitted to synthesize the ester in irreversible manner, therefore improving the performance of the enantioselective esterification. This convenient procedure permitted to prepare (S)-fenoprofen in good yield and in high optical purity.