Synthesis of phenyl 2-acetamido-2-deoxy-4-O-α-l-fucopyranosyl-β-d-glucopyranoside and p-nitrophenyl 2-acetamido-2-deoxy-6-O-α-l-fucopyranosyl-β-d-glucopyranoside

The reaction of phenyl 2-acetamido-3,6-di-O-acetyl-2-deoxy-β-d-glucopyranoside with 2,3,4-tri-O-benzyl-α-l-fucopyranosyl bromide (catalyzed by bromide ion) proceeded readily, to give the protected, 4-O-substituted α-l-fucopyranosyl derivative which, on O-deacetylation, followed by hydrogenolysis, gave phenyl 2-acetamido-2-deoxy-4-O-α-l-fucopyranosyl-β-d-glucopyranoside. The reaction of 2-acetamido-1,3,4-tri-O-acetyl-2-deoxy-β-d-glucopyranose with the same glycosyl bromide under similar conditions gave the protected disaccharide derivative which, on hydrogenolysis, furnished 2-acetamido-1,3,4-tri-O-acetyl-2-deoxy-6-O-α-l-fucopyranosyl-β-d-glucopyranose (9). Treatment of compound 9 with acetyl chloride provided the corresponding glycosyl halide which, on reaction with sodium p-nitrophenoxide in N,N-dimethylformamide, gave compound 12. O-Deacetylation of 12 gave p-nitrophenyl 2-acetamido-2-deoxy-6-O-α-l-fucopyranosyl-β-d-glucopyranoside. The synthesis of p-nitrophenyl 2-acetamido-2-deoxy-6-O-β-l-fucopyranosyl-β-d-glucopyranoside is also described. The structures of the final disaccharides were established by ¹H- and ¹³C-n.m.r. spectroscopy.