Reverse orthogonal strategy for oligosaccharide synthesis

Abstract

Herein, we report the invention of a novel expeditious concept for oligosaccharide synthesis. Unlike the classic orthogonal strategy based on leaving groups, the reverse approach is based on orthogonal protecting groups, herein p-methoxybenzyl and 4-pentenoyl, which allows for efficient oligosaccharide assembly in the reverse direction.

Scheme 1

(a) Conventional linear synthesis involving separate glycosylation and deprotection steps. (b) Ogawa’s leaving group-based orthogonal strategy. (c) New reverse orthogonal concept based on orthogonal protecting groups.

Scheme 2

Four-step synthesis of pentasaccharide 6 via the reverse orthogonal strategy.

Scheme 3

Preliminary investigation of secondary glycosyl acceptors 7a and 7b.