Reaction of epoxides with activated DMSO reagent. General method for synthesis of α-chlorocarbonyl compounds: application in asymmetric synthesis of (3S)-2,3-oxidosqualene

Reaction of a variety of epoxides with DMSO-Oxalyl chloride in the presence of a catalytic amount of methanol and a base was studied. Disubstituted epoxides gave α-chloroketones in high yields. Aliphatic terminal epoxide underwent opening reaction to provide α-chloroketone as a major product. Trisubstututed epoxides provided α-chloroketones as major products through the formation of more stable carbocation. In case of a homoallylic alcohol, enedione was obtained. The efficiency of the method was shown by applying it to the enantioselective synthesis of (3S)-2,3-oxidosqualene