Cooperative Catalysis in Glycosidation Reactions with <i>O</i>‐Glycosyl Trichloroacetimidates as Glycosyl Donors

Abstract

Thiourea mediates cooperative glycosidation through hydrogen bonding. N,N'-Diarylthiourea as cocatalyst enforces an SN2-type acid-catalyzed glycosidation even at room temperature (see scheme; Bn=benzyl). From O-(α-glycosyl) trichloroacetimidates as glycosyl donors and various acceptors, β-glycosides are preferentially or exclusively obtained.