Practical synthesis of a tetrasaccharide derivative corresponding to ristomycin A and ristocetin A

Article abstract of DOI:10.1016/S0008-6215(00)00303-7

A practical synthesis of fully benzoylated tetrasaccharide, whose free form is indispensable to the antibiotic ristomycin A for the process of dimerization and binding to the cell wall, was achieved via sequential assembly of the building blocks, allyl 3,4-di-O-benzoyl-α-D-glucopyranoside, 2,3,4-tri-O-benzoyl-α-L-rhamnopyranosyl trichloroacetimidate, 2-O-acetyl-3,4,6-tri-O-benzoyl-α-D-mannopyranosyl trichloroacetimidate, and 2,3,5-tri-O-benzoyl-α-D-arabinofuranosyl trichloroacetimidate. A one-pot preparation of allyl 3,4-di-O-benzoyl-2-O-tert-butyldimethylsilyl-6-O-triphenylmethyl-α-D- glucopyranoside is described, and regioselective glycosylation is carried out using perbenzoylated sugar trichloroacetimidates as glycosyl donors in the presence of a catalytic amount of trimethylsilyl trifluoromethanesulfonate (TMSOTf).