Stereoselective Synthesis of Highly FunctionalizedC-Glycosides based on Acetal [1,2] and [1,4] Wittig Rearrangements

Abstract

Two types of highly functionalized C-glycosides were stereoselectively synthesized from an ethynylvinylmethanol-derived O-glycoside in one step through acetal Wittig rearrangements (see scheme). The [1,2] Wittig rearrangement affords the 1β-C-glycoside that has contiguous quarternary chiral centers at the C1 and C1′ positions, while the [1,4] Wittig rearrangement has been used for the first time in the synthesis of C-glycosides.