Synthesis of the tetrasaccharide lipid intermediate P1-Dolichyl P2-[O-α-D-mannopyranosyl-(1→6)-O-β-D-mannopyranosyl-(1→4)-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)- (1→4)-2-acetamido-2-deoxy-α-D-glucopyranosyl] disphosphate

Abstract

O-α-D-Mannopyranosyl-(1→6)-O-β-D-mannopyranosyl-(1→4)-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-(1→4)-2- acetamido-2-deoxy-D-glucopyranose was isolated from bovine or ovine mannosidosis urine. After peracetylation, treatment with trimethylsilyl trifluoromethanesulfonate gave a high yield of a peracetyl oxazoline, which was phosphorylated with dibenzyl phosphate to give a dibenzyl glycosyl phosphate that was converted into a peracetyl tetrasaccharide phosphate by catalytic hydrogenolysis. A coupling reaction with P1-dolichyl P2-diphenyl diphosphate, prepared in two stages from pig-liver dolichol, yielded a peracetyl diphosphoric diester, which on O-deacetylation gave P1-dolichyl P2-[O-α-D-mannopyranosyl-(1→6)-O-β-D- mannopyranosyl-(1→4)-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-(1→4)-2-acetamido-2-deoxy-α-D-glucopyranosyl] diphosphate. This tetrasaccharide lipid intermediate was active as an acceptor of D-mannose residues from GDP-D-mannose in the presence of calf pancreas microsomes.