Aminosugars. XX. Synthesis of Some Derivatives of 2-Acetamido-2-deoxy-d-mannose

Abstract

Abstract Preparation of 2-acetamido-2-deoxy-d-mannose (2) by epimerization of the corresponding d-glucose was improved by addition of Ni2+ ion to the equilibration system, and several derivatives of (2) were synthesized. N-glycosides were obtained by using ammonium chloride as a catalyst, and p-nitrophenyl glycoside by a fusion method. The composition of four isomers in benzylglycosidation of (2) was determined to be 66% α-pyranoside (6), 11% β-pyranoside, 16% α-furanoside (5) and 7% β-furanoside. Benzylidenation of 6 gave the corresponding 4,6-O-benzylidene derivative which was converted into the 3-O-acetate (8) by acetylation, and to the corresponding 2-amino-2-deoxy derivative by treatment with ethanolic potassium hydroxide. Oxidation of 6 with oxygen in the presence of platinum-charcoal and following esterification gave the corresponding methyl uronate which was derived to the di-O-acetate (11). Periodate oxidation and the following hydrogenation of 5 gave benzyl 2-acetamido-2-deoxy-α-d-lyxofuranoside which was then derived to di-O-acetate (13). Nitromethane condensation of 2 in barium hydroxide solution gave one isomeric 1-C-nitro-1-deoxy-d-heptitol which was converted into methyl 3-acetamido-3-deoxy-d-gaycero-d-galacto-α-heptopyranoside (18). First-order analyses of NMR spectra of 8, 11, 13, and tetra-O-acetate of 18 are described.