Oxidation of Acetals, an Orthoester, and Ethers by Dioxiranes through Alpha-CH Insertion

Dimethyldioxirane (1a) and methyl(trifluoroinethyl)dioxirane (1b) efficiently afford cleavage of acetals and of ketals to carbonyl products under mild, neutral conditions. Dialkyl ethers are cleaved to alcohols. aldehydes and/or carboxylic acids, whereas reaction of dioxiranes 1a,b with medium-ring cyclic ethers transforms the latter into lactones, via the corresponding hemiacetals, with no appreciable formation of ring-opened products. The products can be accounted for on grounds of a remarkably selective O-atom insertion by the dioxirane into C-H bonds alpha to the ether functionality.