Synthesis of β-rhamnose containing ready to conjugate tetrasaccharide repeating unit corresponding to the K141 CPS of Acinetobacter baumannii KZ1106

Abstract

Herein, we developed an efficient chemical synthetic strategy of a tetrasaccharide repeating unit corresponding to the K141 type capsular polysaccharide of Acinetobacter baumannii KZ1106. The synthesis of the propylamine-linked tetrasaccharide is executed through an efficient [2 + 2] block glycosylation strategy. The construction of a synthetically challenging β-L-rhamnopyranosyl linkage was achieved through ‘armed-disarmed’ glycosylation, with the assistance of a picolinoyl group located remotely through the hydrogen bond mediation effect. The conjugation-ready target oligosaccharide presents a compelling opportunity for the subsequent formation of glycoconjugates with an appropriate aglycon.