Methyl hexopyranosides

All of the mono-O-methylated hexopyranosides are sweet, with only a trace of bitterness. The bitterness is more pronounced in the methyl glycoside derivatives, and this was attributed to the presence of two lipophilic centers (—OMe) in the methyl glycosides and only one in the a,a-trehalose analogs. ... 

A dependence between the relative intensity of a number of peaks and the configuration at C-2 to C-5 has also been found for the permethylated methyl hexopyranosides.1 For example, the Di peak (m/e 149) in the spectrum of methyl tetra- O-methyl-a-D-galactopyranoside is more intense than in that of methyl tetra-O-methyl-a-D-gluco- and -manno-pyranosides, and the peak m/e 145 has the highest intensity in the latter and is considerably diminished in the spectra of the two former compounds. The interpretation of this fact presented in the original paper1 is wrong, because the structures proposed for ions m/e 149 and 145 were incorrect (see References 13 and 15). 

Conditions for use in the reductive-cleavage analysis of permethylated polysaccharides (Bp3.0Et2 or TmsOTf, 1,2-dichloroethane, 70 °C) wherein all 2-deoxy-2-acetamido-A-methyl-hexopyranoside residues are converted into oxazolinium ions, e.g. 68, which give methyl glycosides, e.g. 69, on quenching... 

Dasgupta F, Singh P, Srivastava HC (1988) Use of ferrie ehloride in earbohydrate reactions. Part V. Acetolysis of methyl hexopyranosides using fade chloride in acetie anhydride. Indian J Chem 278 527-529... 

Methyl 4,6-O-benzylidene-3-C-methyl a-D-allopyranoside, M-224 Methyl 4,6- 0 -benzylidene-2- O -methyl -hexopyranosid-3-ulose,... 

Addition of caesium fluoride to the reaction gave a 2 1 ratio of 3- to 2-0-benzyl ethers. The regioselective benzylation of some methyl hexopyranosides has been studied (i,Bu2SnO, toluene ii,BnBr, 85°C). Generally the same products were obtained as with (Bu3Sn)20, but often in better yields. ... 

Lithium hydroperoxide has been shown to cause preferential deacetylation at 0-2 of methyl hexopyranoside peracetates. Selective hydrolysis at 0-1 of either anomer of glucose pentaacetate has been effected with ethanolamine, and per(monochloro)acetylated... 

C13H19NO5, Methyl hexopyranoside derivative, 40B, 301 C13H2 oOs r 1-O-Acetyl-2,3 4,5 di 0-isopropylidene-6-erythro-pent-1 -enitol, 43B, 548... 

The c.i.(CH and i-C4H )-m.s. of acetylated glyco-furanosyl and -pyranosyl fluorides has been investigated and the influence of configuration reported.other reported c.i.-m.s. studies have been on nitro-sugars (in which negative ion analysis gave [M+NOa] peaks), methyl hexopyranoside nitrates, and the xanthate and S roethylthiocarbonate derivatives of l,2 5,6-di-Q-isopropylidene-3- -methyl-c(-D-allofuranose. 

The C n.m.r. spectra of methyl hexopyranosides having methyl groups attached at either C-2 or C-4 have been discussed the resonances for axial C-methyl groups were found ca. 6 p.p.m. upheld from those of the corresponding equatorial groups. ... 

Pyruvate acetals of methyl hexopyranosides have been prepared oxidation of the corresponding furan-2-ylidene derivatives, e.g. compound (10), which in turn were obtained by facile acetal exchange between the sugar 4,6-dicd and 2-acetylAnan dimethylacetal (see Vol, ... 

The conversion of primary alcohols into chlorofluoroacetic esters is referred to in Chapter 7, while the formation of the unusual L-rhamnopyranosyl esters (22) and (23) is dealt with in Chapter 3. The advantages of using trifluoro-acetyl derivatives in the m.s. of methyl hexopyranosides is referred to in Chapter 24. ... 

The regioselecdvity in tin-mediated monotosyladons of diols has been studied use of dibutyldn oxide or hexamethylenetin oxide in the example shown in Scheme 8 gave the primaiy-62 and secondary tosylate 63 in the rados 3 7 and 20 1, respecdvely. A rqxnt on the leacdons of dimesylated methyl hexopyranosides and glucofuranoses with superoxide (KOj) to give hydroxy products, either by direct hydrolysis, nucleophilic displacement, or via transient epoxides, has been published. Amberlite IRA-410 (Cl form) resin in DMF has been recommended for the selective displacement by chlorine of the primary sulfonyloxy groups in 3,5-disulfonate derivatives of 1,2-0-cyclohexylidene-a-D-xylofuranose. ... 

Enzyme-catalyzed regioselective or enantioselective reactions are useful techniques in the organic synthesis of various bioactive substances. Numerous investigators have report on such reactions in aqueous [82] or microaqueous oi anic environments [83], Recently, the authors reported the regioselective deacetylation of peracetylated monosaccharide derivative by PEG-lipase from C. cylindracea [84]. Using a series of peracetylated methyl hexopyranosides as the substrates, it was demonstrated that PEG-lipase catalyzed the ester hydrolytic reaction only at C-4 and C-6 and never hydrolyzed the acetyl groups at C-2... 

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