Enzyme-catalysed Baeyer-Villiger oxidations

Preparative-scale biotransformations of cyclic and bicyclic ketones yielding optically active lactones are illustrated. The use of whole cell systems such as Acinetobacter calcoaceticus to stereoselectively oxidize bicycle[3.2.0]heptanones and bicyclo[2.2.1]heptanones to gamma-lactones and delta-lactones respectively is typical of this increasingly popular strategy. Similarly isolated enzymes (e.g. from Pseudomonas putida) have been used to oxidize monocyclic ketones in an enantioselective fashion. The employment of these biotransformations in the synthesis of natural products such as lipoic acid, multifidene, cyclosarkomycin demonstrate the power of the methodology. A mechanistic rationale and an active site model are discussed. (C) 1998 Elsevier Science B.V.