Methyl-a-D-glucopyranoside

A mixture of d- and l- hexoses also results from the hydroboration of these 5-enes. Hydroboration results in anti-Markownikoff, cw-hydration of the double bond and the amount of each hexose formed varies according to the nature of the substituent groups. For example, hydroboration (23) of methyl 6-deoxy-a-D-ryZo-hex-5-enopyranose (3) affords methyl a-D-glucopyranoside and methyl / -L-idopyranoside in the ratio of 1 2.5 respectively whereas hydroboration of the fris-trimethylsilyl ether of 3 afforded them in the ratio 1 0.6 respectively. The hydroboration method can be used to achieve specific labelling of hexoses with tritium methyl-/ -L-idopyranoside[5-H3] and methyl a-D-glucopyranoside [5-H3] were thus prepared (23). Similarly, hydroboration of the D-Zt/ro-hex-5-eno derivative (14) with diborane-H3 followed by removal of the isopropyli-dene group, afforded methyl a-D-mannopyranoside [5-H3] and methyl / -L-gulopyranoside [5-H3] in the ratio of 1 2 respectively (23). 

Sinclair (92) has described an improved method for the preparation of methyl 6-chloro-6-deoxy- -D-glucopyranoside (137) from methyl a-D-glucopyranoside (11). The reaction was effected with sulfur monochloride S2C12 in N,N-dimethylformamide at room temperature and the... 

Methyl a-D-glucopyranosid-4-0-yl)pyruvic acid [or methyl 4-0-(oxalomethyl)-a-D-glucopyranoside]... 

If the 3- and 4-hydroxyl groups constitute the Shallenberger AH,B unit, it is possible that a disaccharide (such as a,a-trehalose) and methyl a-D-glucopyranoside may possess the same molar sweetness. By a ranking procedure, and using trained panelists in a Paired Comparison Test, it was, indeed, found that isomolar solutions of these two sugars are equi-... 

Aldrich and used for all oxidation experiments. TEMPO, sodium hydroxide, sodium sulfide, formaldehyde, ethylamine and methyl-a-D-glucopyranoside were reagent grade or higher and were used as received from Sigma and Aldrich. 

The acetylation of methyl-a-D-glucopyranoside with A-acetylimidazole (DMF, room temp., 48 h) affords no significant selectivity, and leads to partial substitution at all four hydroxyl groups (2-OAc 3-OAc 4-OAc 6-OAc = 35 15 20 35). 19 1... 

Although there were early reports on the selective acylation72,73 and p-toluenesulfonylation73 of methyl a-D-glucopyranoside, and the p-toluenesulfonylation of methyl a-D-galactopyranoside,74 to yield... 

The rationalization just presented highlights an important point. For methyl a-D-glucopyranoside, deductions based on the analysis of yields of products probably lead to a measure of the relative reac-... 

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