'Designer yeast': A new reagent for enantioselective Baeyer-Villiger oxidations

The catalytic repertoire of baker's yeast has been expanded to include enantioselective Baeyer-Villiger oxidations. To create this catalyst, the Acinetobacter sp. cyclohexanone monooxygenase gene was inserted into a yeast expression vector and this was used to create a 'designer yeast' that performed oxidation reactions. Whole cell-mediated Baeyer-Villiger reactions were carried out on a 1.0 mmol scale and several cyclic ketones were converted in 20-30 h into the corresponding lactones in isolated yields of 60-83%. Under the reaction conditions, ketone reduction constituted only a minor side-reaction. Oxidation of prochiral 4-substituted cyclohexanones produced lactones with very high enantioselectivities.