Enzymatic formation and esterification of (S)-mandelonitrile

The (S)-selective hydroxynitrile lyase from Hevea brasiliensis (HbHNL) cata lyzes the trans-cyanohydrin reaction (transcyanation). The equilibrium of t his two-step reaction sequence is not favorable unless a large excess of ac etone cyanohydrin (1) is used. Therefore, the coupling of this reaction wit h a follow-up reaction was investigated. It was established that the trans- cyanohydrin reaction could be performed in organic media, making it possibl e to couple it with a lipase-catalyzed acylation. Candida antarctica lipase B (CAL-B) shows a high selectivity (E = 100) for (S)-mandelonitrile (4) an d is, therefore, the ideal candidate for this type of multi-step one-pot re action. (C) 2001 Elsevier Science B.V. All rights reserved.