K. Matta, S. S. Rana, S. Abbas
Aug 15, 1984
Citations
0
Influential Citations
11
Citations
Journal
Carbohydrate Research
Abstract
Abstract Acetalation of o -nitrophenyl 2-acetamido-2-deoxy-α- d -galactopyranoside with p -methoxybenzaldehyde-zinc chloride complex afforded the 4,6- O -( p -methoxybenzylidene) derivative ( 1 ). Acetylation of 1 with pyridine-acetic anhydride gave the crystalline monoacetate ( 2 ), the acetal group of which was cleaved by brief treatment with hot, 80% aqueous acetic acid to furnish the diol ( 3 ). The 1 H-n.m.r. spectra of both 2 and 3 supported their overall structures. Glycosylation of 3 with 2,3,4,6-tetra- O -acetyl-α- d -galactopyranosyl bromide ( 5 ) in 1:1 nitromethane-benzene, in the presence of mercuric cyanide, afforded the disaccharide derivative ( 6 ). O -Deacetylation of 6 in methanolic sodium methoxide gave the title disaccharide ( 8 ). A similar glycosylation of benzyl 2-acetamido-3- O -acetyl-2-deoxy-α- d -galactopyranoside with bromide 5 , followed by O -deacetylation of the resulting intermediate, produced disaccharide 9 . The structures of 8 and 9 were confirmed by 13 C-n.m.r. spectroscopy. Hydrogenolysis of the benzyl aglycon of 9 gave the free disaccharide 2-acetamido-2-deoxy-6- O -β- d -galactopyranosyl- d -galactopyranose ( 13 ). The 13 C-n.m.r. spectrum of 13 is recorded, and discussed in conjunction with those of the β-(1→3)- and the β-(1→4)-linked isomers.