Organic peracid oxidation of α-cyclopropylidene ketones and acetals substituted in the vinylic position leads to the corresponding oxaspiropentyl ketones and acetals. Esters are also formed from the products of the Baeyer-Villiger oxidation; they are easily removed from the crude product. Unsubstituted oxaspiropentyl ketones are not obtained by this method; they are obtained by oxidation of oxaspiropentyl alcohols (formed by epoxidation of α- ...