An efficient synthesis of ganglioside GM3: highly stereocontrolled glycosylation by use of auxiliaries

Article abstract of DOI:10.1016/0008-6215(90)80018-X

An efficiently stereocontrolled total synthesis of GM₃ α-D-Neup5Ac-(2->3)-β-D-Galp-(1->4)-β-D-Glcp-(1->1)-Cer as achieved by employing both methyl 5-acetamido-4,7,8,9-tetra-O-benzyl-2-bromo-2,3,5-trideoxy-3-phenylthio-D-erythro-β-L-gluco-2-nonulopyranosonate for the key sialylation step, and O--(2->3)-O-(2,4,6-tri-O-acetyl-β-D-galactopyranosyl-(1->4)-3,6-di-O-acetyl-2-O-pivaloyl-α-D-glucopyranosyl trichloroacetimidate and fluoride for the key coupling step with a ceramide derivative.These two steps were significantly altered and improved in comparison with our previous synthesis that had been executed without use of stereocontrolling auxiliaries.GM₃ was obtained in 4.5percent overall yield in 19 steps starting from allyl O-(2,6-di-O-acetyl-3,4-O-isopropylidene-β-D-galactopyranosyl)-(1->4)-2,3,6-tri-O-acetyl-β-D-glucopyranoside.