Stereoselective Synthesis of a Tetrasaccharide Fragment from Cellulosome Produced by Clostridium thermocellum

Abstract

AbstractAn efficient synthesis of a structurally congested tetrasaccharide portion from the cellulosome produced by Clostridium thermocellum has been accomplished through a stepwise glycosylation strategy. The key steps for the synthesis include the stereocontrolled construction of a range of challenging 1,2‐cis glycosidic linkages. The 5‐O‐(2‐quinolinecarbonyl) substituted D‐galactofuranosyl thioglycoside 2, 4,6‐O‐benzylidene protected 2‐azido‐2‐deoxyglucose thioglycoside 3 c, and 4,6‐O‐benzylidene protected D‐galactopyranosyl thioglycoside 4 were employed as glycosyl donors, respectively, for the high‐yielding and stereoselective formation of the corresponding 1,2‐cis‐α‐Galf, α‐GlcNAc, and α‐Galp linkages.