OXIDATION OF 2,3,4,6-TETRA-O-METHYL-D-GLUCOSE WITH ALKALINE HYDROGEN PEROXIDE

Article abstract of DOI:10.1016/S0008-6215(00)85701-8

Treatment of 2,3,4,6-tetra-O-methyl-D-glucose with 10 molar equivalents of 30percent aqueous hydrogen peroxide and 2 molar equivalents of potassium hydroxide afforded, after chromatographic separation, 2,3,4,6-tetra-O-methyl-D-gluconolactone, 1-O-formyl-2,3,5-tri-O-methyl-D-arabinose methyl hemiacetal (7), 2,3,5-tri-O-methyl-D-arabinonolactone, methyl 2,3,5-tri-O-methyl-D-arabinoside, O-(2,4-di-O-methyl-D-erythrose)-(1'<*>3)-2,4-di-O-methyl-D-erythronic acid, and O-(2,4-di-O-methyl-D-erythrose)-(1'<*>2)-3-O-methyl-D-glyceraldehyde.The proportions of the products depended on the reaction conditions, especially the time, temperature, and the presence or absence of magnesium hydroxide.Formation of the products is explained by a series of reactions beginning with the addition of hydrogen peroxide to the carbonyl form of the methylated sugar.The adduct, with the help of superoxide radical and a molecule of hydrogen peroxide, breaks up in two ways, giving 2,3,4,6-tetra-O-methyl-D-gluconic acid and 7.The formic ester, on hydrolysis, gives 2,3,5-tri-O-methyl-D-arabinose, which undergoes a similar series of reactions, affording 2,3,5-tri-O-methyl-D-arabinonic acid, and presumably, 1-O-formyl-2,4-di-O-methyl-D-erythrose methyl hemiacetal.Apparently, the latter compound, on hydrolysis, forms a dimer, which, with alkaline hydrogen peroxide, undergoes a similar series of reactions, ultimately affording O-(2,4-di-O-methyl-D-erythrose)-(1<*>3)-2,4-di-O-methyl-D-erythronic acid and O-(2,4-di-O-methyl-D-erythrose)-(1<*>2)-3-O-methyl-D-glyceraldehyde.With a larger amount of alkali, under more-severe conditions, oxidation of 2,3,4,6-tetra-O-methyl-D-glucose proceeds further, with production of up to 3 moles of formic acid per mole of methylated sugar.