A-Methyl-</-mannoside

Methyl a-glucoside and methyl a-mannoside [Jeffrey. G. A., McMullan, R. K.. and Takagi, S., Acta... 

The platinum oxide catalyst converts the hexitols to the corresponding aldoses and ketoses which are carried through the above series of reactions by the oxygen. Mannitol is oxidized by Pt02 to D-mannose, isolated as methyl a-mannoside in a yield of 20%. Fructose is formed simultaneously. With a platinum-activated carbon catalyst, L-sorbose has been converted to 2-keto-L-gulonic acid, 2,3-0-isopropylidene-L-sorbose to2,3-0-isopropyl-... 

Methyl a-D-mannopyranoside was treated in succession with p-toluene-sulfonyl chloride, carbonyl chloride, and benzoyl chloride, and, without isolating the intermediates, there was obtained in 37% yield methyl 4-0-l enzoyl-2,3-O-carbony 1-6-0-(p-tolylsulfonyl ) -D-mannoside. The tos-yloxyl group of the latter was replaced by iodine, and hydrogenation of the 6-iodo derivative in the presence of a nickel boride catalyst gave methyl 4-0-benzoyl-2,3-0-carbonyl-6-deoxy- -D-mannoside. Treatment of the latter with hydrogen bromide in acetic acid gave crystalline 4-0-benzoyl-2,3-0-carbonyl-6-deoxy-a-D-mannosyl bromide (8) (16). The... 

J. J. Grimaldi, B. D. Sykes 1975, (Con-canavalin A a stopped flow nuclear magnetic resonance study of conformational changes induced by Mn++, Ca++, and alpha-methyl-D-mannoside),/. Biol. Chem. 250, 1618. 

From methyl-a-D-mannoside a similar product, C7H,0O2(ON02)4, was obtained in the form of needles, melting at 36°C, rather unstable at 50°C. 

This sugar was first prepared by Irvine and Moodie48 by the methyla-tion of methyl a-D-mannopyranoside with methyl iodide and silver oxide in the presence of methanol as solvent. The crystalline methyl tetra-methyl-a-D-mannoside yielded, on acid hydrolysis, sirupy 2,3,4,6-tetra-methyl-D-mannose. Methylation has been carried out subsequently using dimethyl sulfate and sodium hydroxide49 60 and by the reaction of the potassium salt of methyl a-D-mannopyranoside with methyl iodide in liquid ammonia.61 The Haworth methylation procedure has also been... 

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