Synthetic Studies on Sialoglycoconjugates 88: Synthesis of Ganglioside GM₃ and GM₄ Analogs Containing 2- OR 3-Branched Fatty-Alkyl Residues in Place of Ceramide

ABSTRACT

Each of four ganglioside GM₄ and GM₃ analogues containing 2- or 3-branched fatty alkyl residues in place of ceramide have been synthesized. Coupling of O-(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosylonate)-(2→3)-2,4,6-tri-O-benzoyl-α-D-galactopyranosyl trichloroacetimidate (13) or O-(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-α-D-glacto-2-nonulopyranosylonate)-(2→3)-O-(2,4-di-O-acetyl-6-O-benzoyl-β-D-galactopyranosyl)-(1→4)-3-O-acetyl-2,4-di-O-benzoyl-α-D-glucopyranosyl trichloroacetimidate (14) with 2- or 3-branched fatty-alkyl-1-ols (9-12), prepared from the corresponding branched fatty acids by methyl esterification and reduction, using BF₃Ot₂ gave the corresponding ganglioside analogues (15, 17, 19, 21, 23, 25, 27, 29) in good yields, which were coverted, via O-deacylation and de-esterification, into the title compounds.