Methyl glucoside, acetyl derivatives

Several methyl pento- and hexo-pyranosides have been studied as trifluoroacetates in connection with mass spectrometry,391 and the retention times of 41 glycosides as their trifluoroacetates have been compared with those of the O-trimethylsilyl and O-acetyl derivatives.387 In a study on sake, the separation of ethyl D-glucosides as these three derivatives was also compared.299... 

The species Chamomilla recutita (chamomile) is rich in phenolic compounds, cumarines, phenolic acids and, especially, flavonoids such as p-D-glycosyl-7-apigenine and their acetylated derivatives, luteolin glucosides, quercetin heterosides and their methylated genines [90]. Apart from its known antispasmolytic activity, it also protects against ulceration mediated by indomethacin, stress and absolute alcohol. 

In the presence of chloramine T, the non-reducing end oxime 42 underwent 1,3-polar cycloadditions with terminal alkynes to give 3-glycosyI-5-substituted isoxazoles 43 in moderate yields. Reductive alkylation of pyrroline derivative 44 with methyl 2,3,4-tri-0-benzyl-6-deoxy-6-iodo-a-D-glucopyranoside gave, after ester reduction, osmylation and acetylation-deacetylation, the novel poly-hydroxypyrrolidine 45, containing a methyl glucoside moiety. ... 

Saccharin Glucosides.—3-Chloro-l,2-benzisothiazole 1,1-dioxide (64) reacts with nucleophiles (ROH, RSH, or RNHg) to yield products derived from the imide form of saccharin (63). Its reaction in pyridine with 2,3,4,6-tetra-O-methyl(or -acetyl)-ajS-D-glucopyranose similarly gives the readily crystallizable 3-(a-D-glucosyl)-l,2-benzisothiazole 1,1-dioxides (67), irrespective of the configuration of the monosaccharide used. In the absence of base, the reaction... 

Several other methods for the introduction of halo atoms at C-6 in hexose derivatives have been known since the late 1920s. One of the earlier methods involved the reaction of methyl 2,3,4-tri-0-acetyl-6-0-trityl-a-D-glucopyranoside with phosphorus pentachloride which resulted only in an 8% overall yield of methyl 6-chloro-6-deoxy-a-D-glucoside (57). In contrast, the reaction of methyl 2,3,4-tri-0-acetyl-6-0-trityl-a-D-altropyranoside with phosphorus tribromide and bromine afforded a 73% yield of the corresponding 6-bromo-6-deoxy derivative (91). 

A solution of silver nitrate in acetonitrile converts co-deoxy-oj-iodo-aldo.se derivatives to the corresponding w-nitrates without20 123 260 occurrence of desulfonylation. Thus, methyl 2,3-di-0-acetyl-6-deoxy-6-iodo-4-0-tosyl-/3-D-glucoside gave20 an 89% yield of the 6-nitrate after boiling for 2 hours. Boiling for 4 hours was required for preparation of methyl 2,3,4-... 

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