Dimethyl sulfate glycoside formation

Haworth methylation. Formation of methylated methyl glycosides from monosaccharides with dimethyl sulfate and 30% sodium hydroxide. The glycosidic methyl group is hydrolyzed with acid to yield the free methylated sugar. 

The glycosidic hydroxyl undergoes preferential alkylation when the sugar is alkylated with one equivalent of dimethyl sulfate and alkali 49,4 0 ). The procedure is particularly valuable for obtaining methyl glycosides of the D-mannose type for which the Koenigs-Knorr reaction fails because of orthoester formation. Alkylation of tetra-0-acetyl-/3-D-fructopyranose with silver oxide and methyl iodide leads to the methyl /8-D-fructopyranoside tetraacetate 50). 

Methylation of X with silver oxide and methyl iodide gave the lactone of methyl 2,5-dimethyl-j8-D-glucofururonoside (XIII) which was characterized by its conversion to the crystalline amide (XIV). Further methylation of XIII, form, with methyl sulfate and sodium hydroxide gave methyl 2,3,5-trimethyl-/3-D-glucofururonoside (XVI) from which by hydrolysis of the glycosidic methyl group and subsequent oxidation with bromine, there was obtained 2,3,5-trimethyl-D-glucosaccharolactone (XVII) characterized by the formation of its crystalline methyl ester. 

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