Synthesis of the 3- and 4-methyl, 3,4-dimethyl, and 3,4,6-trimethyl ethers of methyl 2-acetamido-2-deoxy-α- D-mannopyranoside

Abstract

The methyl ethers of 2-amino-2-deoxy- D-mannose are reference compounds in studies, by the methylation procedure, of the chemical structure of polysaccharides containing 2-amino-2-deoxy- D-mannose and 2-amino-2-deoxy- D-mannuronic acid residues. Methylation of methyl 2-acetamido-2-deoxy-α- D-mannopyranoside ( 1) gave the 3,4,6-trimethyl ether. Methylation of the 6-trityl ether of 1, followed by detritylation, gave the 3,4-dimethyl ether of 1. Methylation of the 4,6- O-benzylidene derivative ( 6) of 1, followed by removal of the benzylidene group, gave the 3-methyl ether of 1. Benzoylation of 6, followed by removal of the benzylidene group and monobenzoylation, gave the 3,6-dibenzoate of 1, which was methylated, and the product saponified, to give the 4-methyl ether of 1; the latter compound was also obtained by a similar route via the 3- O-acetyl-6- O-benzoyl derivative.