Dichloromethylenation of 1,4-lactones. A new access to 1-deoxy-1- C-methyl- C-glycosyl compounds

Abstract

Sugar 1,4-lactones reacted with hexamethylphosphorous triamide-tetrachloromethane to give dichloroolefins in one step. These compounds are versatile intermediates. Treatment of these 1,1-dichloro-1,1-dideoxy-3,4,- O-isopropylidene derivatives with lithium diisopropylamide gave the corresponding 4-deoxy-3-ulo derivatives. Reduction of the dichloromethylene group gave a methyl group with high stereospecifity. This opens the way to a set of 2,5-anhydro-1-deoxyalditols.