title: Analysis of linkage positions in 2-acetamido-2-deoxy-D-glucopyranosyl residues by the reductive-cleavage method.
abstract: The fate of methylated 2-acetamido-2-deoxy-D-glucopyranosyl residues under reductive-cleavage conditions was investigated by using methyl 2-(acetylmethylamino)-2-deoxy-3,4,6-tri-O-methyl-beta-D-glucopyran oside (1), its alpha anomer (8), and fully methylated lacto-N-tetraitol as test compounds. Treatment of 1 with triethylsilane and trimethylsilyl trifluoromethanesulfonate in dichloromethane gave rise to (1,2-dideoxy-3,4,6-tri-O-methyl-alpha-D-glucopyrano)-2,3-dimethyl- [2,1-d]-2- oxazolinium trifluoromethanesulfonate. Quenching of the reaction by addition of aqueous sodium hydrogencarbonate resulted in hydrolysis of the oxazolinium salt. Compound 8 was fully stable to reductive-cleavage conditions. Thus, participation by the 2-acetamido group is necessary for glycosidic carbon-oxygen bond-cleavage to occur. Treatment of methyl 2-deoxy-2-(ethylmethylamino)-3,4,6-tri-O-methyl-alpha,beta-D-gluco pyranoside under reductive-cleavage conditions resulted in some anomerization, but neither hydrolysis nor reductive cleavage of the glycosidic carbon-oxygen bond was observed, as expected. Reductive cleavage of fully methylated lacto-N-tetraitol gave the products predicted on the basis of these and prior model studies, including 3-O-acetyl-2-(acetylmethylamino)-2-deoxy-4,6-di-O-methyl-D-glucopy ranose derived from the 3-linked 2-acetamido-2-deoxy-beta-D-glucopyranosyl residue.
mesh_terms: D000117:Acetylglucosamine; D002236:Carbohydrate Conformation; D005944:Glucosamine / Q000031:analogs & derivatives; D006027:Glycosides; D006868:Hydrolysis; D007202:Indicators and Reagents; D008745:Methylation; D010084:Oxidation-Reduction
chemical_list: D006027:Glycosides; D007202:Indicators and Reagents; D005944:Glucosamine; D000117:Acetylglucosamine