The system Sn-Beta/hydrogen peroxide is applied to the Baeyer–Villiger oxidation of delfone to δ-decalactone, which is an industrial fragrance. The reaction is carried out without solvent and with a substrate/catalyst ratio>200 (wt/wt). Starting with an enantiomerically enriched delfone it is shown that the rearrangement occurs with retention of configuration at the migrating asymmetric carbon atom, and enantiomerically enriched δ-decalactone is obtained as product. This process offers clear advantages over the actual industrial production that uses peracids as oxidants.