Methylation of reducing carbohydrates. Permethylated derivatives of melibiose [O-α-D-galactopyranosyl-(1 → 6)-D-glucopyranose]

Abstract

Methylation in methanol of α-melibiose and octa-O-acetyl-β-melibiose with ethereal diazomethane, and subsequent permethylation (methyl iodide–barium oxide), gave methyl hepta-O-methyl-β-melibiopyranoside (IV). When α-melibiose was methylated with methyl iodide and barium oxide, a mixture of furanose and pyranose isomers was obtained, from which pure methyl hepta-O-methyl-α-melibiofuranoside [methyl hepta-O-methyl-O-α-D-galactopyranosyl-(1 → 6)-α-D-glucofuranose](I) was isolated. The preparation of methyl hepta-O-methyl-β-melibiofuranoside (II) is reported.