2,3,4,6-Tetra-O-methylglucose

Trehalose is a nonreducing disaccharide that is hydrolyzed by aqueous acid to yield 2 equivalents of D-glucose. Methylation followed by hydrolysis yields 2 equivalents of 2,3,4,6-tetra-O-methylglucose. How many structures are possible for trehalose ... 

Trehalose is a nonreducing disaccharide (C12H22O11) isolated from the poisonous mushroom Amanita muscaria. Treatment with an a-glucosidase converts trehalose to two molecules of glucose, but no reaction occurs when trehalose is treated with a j3-glucosidase. When trehalose is methylated by dimethyl sulfate in mild base and then hydrolyzed, the only product is 2,3,4,6-tetra-O-methylglucose. Propose a complete structure and systematic name for trehalose. 

Fig. 4.—Mass Fragmentography (m/e 161) of Methylated Hexose Derivatives from the Disialosy] Ganglioside. [Top, before treatment with neuraminidase bottom, after treatment with Vibrio cholerae neuraminidase. The methylated hexose derivatives identified are (A) 2,4,6-tri-O-methylgalactose (B) 2,3,6-tri-O-methylglucose (C) 2,3,4,6-tetra-O-methylgalactose. The peaks eluting before C are unrelated signals that were also detected in a blank experiment employing the neuraminidase treatment. Conditions 3% of QF-1, at 190°. Reproduced, by permission, from Ref. 80.]...

D-Raffinose is a trisaccharide that does not react with Fehling s solution. Upon hydrolysis it produces D-glucose, D-galactose/ and D-fructose. Completely methylated raffinose is hydrolyzed to 2,3,4-tri-O-methylglucose, 1,3,4,6-tetra-O-methylfructose, and 2,3,4,6-tetra-O-methylgalactose. What structures for raffinose are consistent with these data What further information, if any, is required to identify completely the structure of raffinose ... 

With respect to reference compounds key rhamnose A tetra-O-methylglucose "glucose. Solvents 1, 1-butanol-acetic acid-ammonia-water (40 50 3 15) 2,1-butanol-water 3,1-butanol-pyridine- water (6 4 3) 4, l-butanol- ethanol-water (4 1 5, upper phase) 6t 1-butanol-ethanol-water (40 11 19) 6, 1-butanol-acetic acid-water (4 1 1). References are given in parentheses. 

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