Convergent synthesis of a tetrasaccharide repeating unit of the O-specific polysaccharide from the cell wall lipopolysaccharide of Azospirillumbrasilense strain Sp7

Abstract

A straightforward convergent synthetic strategy has been developed for the synthesis of the tetrasaccharide repeating unit of the O-specific cell wall lipopolysaccharide of Azospirillumbrasilense strain Sp7. The target tetrasaccharide has been synthesized in excellent yield using a [2+2] block glycosylation approach with minimum number of steps. The intermediate step in the synthetic scheme involves stereoselective glycosylation and protecting group manipulations in one-pot. All glycosylation steps are high yielding and stereoselective.