Chemo-enzymatic Baeyer–Villiger oxidation of cyclopentanone and substituted cyclopentanones

Chemo-enzymatic oxidation of cyclopentanones and substituted cyclopentanones to the corresponding δ-valerolactones was investigated employing catalytic amount of Candida antarctica lipase-B in ethyl acetate and employing urea–hydrogen peroxide as the oxidant. In contrast to the smooth oxidation of cyclohexanones to the corresponding ɛ-caprolactones, the δ-valerolactones reacted further with the lipase delivering trans-esterified products and also acetylated alcohols, depending on the structural nature of the cyclopentanones.