2′-Carboxybenzyl glycosides: glycosyl donors for C-glycosylation and conversion into other glycosyl donors

Glycosylation of various glycosyl acceptors with 2′-carboxybenzyl (CB) 2,3,4,6-tetra-O-benzyl-β-d-glucopyranoside and CB 2,3,4,6-tetra-O-benzyl-α-d-mannopyranoside as glycosyl donors afforded α-C-glycosides exclusively or predominantly in good yields. CB glycosides were also converted to other well-known glycosyl donors, the corresponding phenyl thioglycoside and the glycosyl fluoride derivatives.