Methyl £-D-xyloside

D-Xylose (b) D-Glucose (c) D-Galactose (d) Methyl D-Xyloside (e) Methyl D-Glucoside and (f) Methyl D-Galactoside. (Redrawn from Refs. 4 and 5.)... 

Hockett RC, Hudson CS (1931) A novel modification of methyl-d-xyloside, a novel modification of lactose. J Am Chem Soc 53 4454-4456... 

Bishop CT, Cooper FP. Glycosidation of sugars. I. Formation of methyl d-xylosides. Can J Chem 1962 40 224-232. 

Fig. 7.—Predicted (- -) and Fragment (—) Circular Dichroism Spectra /3-L-Arabinose Calculated from (a) a-D-Xylose, and (b) Methyl /3-L-Aiabinoside a-L-Arabinose Calculated from (c) j3-D-Xylose, and (d) Average Calculated for /3-L-Arabinose Methyl a-L-Arabinoside Calculated from (e) Methyl /3-D-Xyloside, and (f) Methyl /3-L-Arabinoside. (Redrawn from Ref. 6.)...

S-D-Xylosidase in extract from Trichoderma reesei Transxylosylation with methyl-/i-xyloside and 1 -butanol Butanol-acetate buffer pH 4.5 Kinetically controlled process 128... 

An interesting observation was made by Ferrier and coworkers61 during the acylation of 2,4-boronic esters of methyl a- and /3-d-xylopyranosides, in both of which the pyranoid ring must be in the C.,(d) conformation, and the 3-hydroxyl group must be axially attached. On treatment with benzoyl chloride in pyridine, the a-d-xyloside derivative gave 37% of the 3-benzoate and 19% of unreacted starting-material, but the /3-D-xyloside derivative yielded... 

Ring contraction also occurred in the deamination of 60 to give methyl 3-deoxy-3-C-formyl-/3-D-xylofuranoside (65) as a minor product, isolated in 5% yield. As the 3-amino-3-deoxy-D-alloside is likely to exist mainly in the chair conformation shown (60), in which the bond to the amino group is axial, and as ring contractions are normally observed in the deamination of equatorial amines, the D-xyloside 65... 

Methyl 2,5-di-0-methyl-3-0-tosyl-/3-D-xyloside Methyl 2,3-0-isopropylidene-5-0-tosyl-L- KOH-aq. EtOH 223... 

The synthesis of 3,4-dimethyl-D-xylose had previously been recorded10 but no direct comparison of similar derivatives of the natural and synthetic product had been made. For the synthesis, methyl 3,5-isopropyli-dene-D-xyloside (a/3 mixture) was converted into the 2-benzoate (XV) which with hot methanolic hydrogen chloride was transformed (presumably) into methyl 2-benzoyl-D-xylopyranosides (a/3 mixture) (XVI)... 

Honeyman oi has reported, on the other hand, that iMlditi in of water to methyl 2,3-anhydro-jS-D-ribopyranoside (Eq. 545) takes place at C(8), rather than Cia>, giving methyl /5 D-xyloside. 

Thus, refluxing methyl P-D-glucoside two equivalents of tributyltin oxide, [(C4Hg)3Sn]20 and molecular sieves (3 A) in chloroform for 2-3 h followed by treatment with two equivalents of bromine at 0 °C furnishes methyl p-D-3-dehydro-3-ketoglucoside in more than 90% yield. Similarly, methyl p-D-xyloside gives the 3-oxo compound, whereas methyl a-D-glu-coside, a-D-galactoside, a-D-xyloside, and p-L-arabinoside yield 70-80% of the corresponding 4-keto derivatives [734],... 

A very interesting synthetic use for periodate-oxidized methyl pento-pyranosides has been developed by Baer and Fischer. Treatment of the dialdehyde from methyl jS-D-pentopyranosides with nitromethane-so-dium methoxide gave an ocf-nitro compound which, after acidification and hydrogenation, gave methyl 3-amino-3-deoxy-j8-D-riboside a small proportion of methyl 3-amino-3-deoxy-i8-D-xyloside was isolated as a by-product. A similar sequence in the u series gave methyl 3-amino-3-deoxy-j8-L-riboside. 

Problem 34.25 When either methyl a-L-arabinoside or methyl j3-D-xyloside is methylated, hydrolyzed, and then oxidized by nitric acid, there is obtained a trimethoxy-glutaric acid, (a) What ring size is indicated for these aldopentosides (b) Predict the products of HIO4 oxidation of each of these aldopentosides. 

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