Synthesis of O-α- d-mannopyranosyl-(1→2)-O-α- d-mannopyranosyl-(1→2)- d-mannose, the repeating unit of the O8-antigen of Escherichia coli

Abstract The trisaccharide α- d -Man p -(1→2)-α- d -Man p -(1→2)- d -Man was synthesised by using a stepwise method. A key reaction in the preparation of the intermediates was the selective hydrogenolysis of mannopyranoside derivatives having both dioxane- and dioxolane-type benzylidene acetals, resulting in the exclusive cleavage of the former acetal rings.