Baeyer-Villiger oxidation of substituted cyclohexanones via lipase-mediated perhydrolysis utilizing urea-hydrogen peroxide in ethyl acetate

A green method for Baeyer-Villiger oxidation based on the chemo-enzymatic perhydrolysis of carboxylic acids and esters has been optimized using Novozyme-435, the immobilized form of Candida antarctica lipase B, and the complex urea-hydrogen peroxide (UHP) in ethyl acetate. This protocol previously employed for the chemo-enzymatic epoxidation of unfunctionalized olefins was shown to be effective for the Baeyer-Villiger oxidation of cyclohexanone and substituted cyclohexanones. The absence of water in the reaction media avoided any hydrolysis of the oxidized product. A minimum amount of enzyme was necessary to show the catalytic effect. The reaction yields of substituted epsilon-caprolactones varied depending on the nature of the substituent.