Unexpected furanose/pyranose equilibration of N-glycosyl sulfonamides, sulfamides and sulfamates

Abstract

De-protected arabino N-glycosyl sulfamides, sulfonamides and sulfamates were found to mutarotate and convert from the furanose to the thermodynamically more stable pyranose form in aqueous solution. The presence of a strongly electron withdrawing group in the alkyl chain stopped mutarotation and furanose/pyranose equilibration, allowing the isolation of the first unprotected furanose N-glycosyl sulfonamide.