Hexoses trimethylsilyl derivatives

The 0-trimethylsilyl derivatives of five reference disaccharide alditols, composed of 2-acetamido-2-deoxyhexitol substituted at C-3, C-4, or C-6 with a hexose grouping, have been studied by g.l.c.-m.s. The data were used in the determination of the linkage in disaccharide alditols derived from rat brain glycoproteins and gangliosides. 

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). 

Ferrieres and Plusquellec described the synthesis of per-acetylated S-benzothiazolyl galactofuranosides from P-D-galactofuranose pentaacetate in the presence of BFs-EtaO in 83% yield as an anomeric mixture (52, 55). The obtained thioimidates were then deprotected and applied in anomeric phosphorylation. A number of acylated S-benzothiazolyl and S-(5-methoxy)benzothiazolyl derivatives of D-gluco, D-galacto, and D-ribofurano series have been reported by Khodair et al (34). While the syntheses of hexoses were accomplished from acetobromosugar and the corresponding sodium thiolates in MeCN, the synthesis of thioribofruunoside derivative was accomplished from ribofiiranose tetraacetate and trimethylsilylated thiols in the presence of TMSOTf (34). 

Mono-, di-, and tri-saccharides can be separated satisfactorily by g.l.c. of their trimethylsilylated oxime derivatives, and an investigation has been conducted into the most selective stationary phases for the separation of mixtures of pentoses and hexoses as their TMS derivatives. Traces of D-glucose and other related impurities in samples of o-glucitol can be detected by g.l.c. of the O-acetyl derivatives. ... 

GC-MS has been widely used in the analysis of carbohydrate materials. The photosynthetic incorporation of C02 into carbohydrates by corn and soyabean plants can be conveniently monitored by this technique using trimethylsilylated oxime derivatives,22 gnd a capillary GC-CI MS procedure has been used to analyse mixtures of pentosesand hexoses via trifluoro-acetylated oxime derivatives. GC-MS data have also been recorded for the products of the formose reaction,permethylated trisaccharide alditols derived from sialic acid-containing glycopeptides, 6 cytokinin ribonucleosides, 7 methylated and... 

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