2.3.6- Tri-O-methylglucose

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.]...

Permethylation of hydroxyl groups makes the 06 side narrower because of the sharp inclination of 2,3,6-tri-O-methylglucose units caused by the steric hindrance between methyl groups bonded to 03 and 02 of adjacent 2,3,6-tri-O-methylglucose unit. As the result, m-nitroaniline [187] and p-nitrophenol [197] are included with their hydroxyl or amino group located at the 06 side, that is, in the orientation upside down compared with the corresponding complex with the parent a-CyD (Fig. 

Whereas ethers of monohydric alcohols or phenols are denoted by alkoxy-, aryloxy-, efe., prefixes or as the -yl -yl ether (with the radical prefixes in alphabetical order), those from polyhydric alcohols and phenols are handled differently. Either the monohydric component is written first, with unchanged -ol ending, as in glycerol 1-ethyl ether, glucose 2,3,6-trimethyl ether or the ether groups are added by means of 0- prefixes, as in 2,3,6-tri-O-methylglucose, 1-0-ethylpyrogallol. The same alternatives exist for esters of polyhydric alcohols. 

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 ... 

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