Synthesis of mono-and di-α-L-fucosylated 2-acetamido-2-deoxy-N-glycyl-β-D-glucopyranosylamines modeling N-glycoprotein carbohydrate-peptide bond region based on 2-acetamido-N-(N-tert-butyloxycarbonylglycyl)-2-deoxy-β-D-glucopyranosylamine

A synthesis of glycyl-spacered N-beta-glycosides of diand trisaccharides such as alpha-l-Fucp-(1 -> 3)-beta-d-GlcNAcp-NHCOCH2NH2 (1), alpha-l-Fucp-(1 -> 6)-[alpha-{asl}-Fucp-(1 -> 3)]-beta-d-GlcNAcp-NHCOCH2NH2 (2), alpha-l-Fucp-(1 -> 6)-beta-d-GlcNAcp-NHCOCH2NH2 ({sn3}), which model the carbohydrate-peptide bond region of fucosylated N-glycoproteins of animals and plants, was accomplished. The synthesis was carried out by the fucosylation of unprotected N-glycoside beta-{}scd-GlcNAcp-NHCOCH(2)NHBoc (Boc is the tert-butyloxycarbonyl) (4), 4,6-O-benzylidene derivative of compound 4, and protected disaccharide 1 (alpha-l-FucpBn(3)-(1 -> 3)-beta-d-GlcNAcp-NHCOCH(2)NHBoc (Bn is the benzyl)) with ethyl 2,3,4-tri-O-benzyl-1-thio-beta-l-fucoside (in the presence of CuBr2 and an excess of Et4NBr). A possibility of the selective ?-fucosylation of N-glycoside 4 at the primary hydroxy group in the presence of secondary hydroxy groups (in 34% yield) was demonstrated. Amino spacered N-glycosides 1-3 were obtained after the removal of protecting groups.