Glycosyl phosphates using

Tetra-Q-benzyl-o-D-glucopyranosyl (diphenyl)phosphate and methyl 2,3,6-tri-Q-benzyl-a-D-glucopyranoside, condensed in the presence of trimethylsilyl triflate, afforded the substituted cellobioside in high yield and with an a ratio of 7 93. This is an unusual use of phosphate esters and is of particular interest since the glycosyl phosphate used is claimed to have appreciable shelf life. ... 

Solid-Phase Oligosaccharide Synthesis Using Glycosyl Phosphates... 

Scheme 6.9 Formation of P-mannosides using glycosyl phosphates...

Scheme 6.12 Rearrangement to C-aryl glycosides from aryl O-glycosides following a-selective synthesis using glycosyl phosphates.

Their characteristic optical rotatory dispersion or circular-dichroism curves, and their infrared spectra, rich in characteristic frequencies, may be useful. Paper chromatography permits preliminary identification of the glycosyl phosphate or monosaccharide resulting after degradation, and the specific enzymic reactions of these products are widely used to provide additional evidence. 

Nucleoside 5 -phosphates are employed as starting materials to prepare the activated derivatives (56). Their synthesis has been discussed in a Chapter in this Series.266 The methods used most frequently for preparing glycosyl phosphates involve the interaction of protected glycosyl bromides with diphenyl phosphate and subsequent removal of the protective groups,267 or by fusion of the peracetylated monosaccharides with anhydrous phosphoric acid.268... 

In all of the foregoing examples, an activated derivative of the nucleotide has been employed for generating the pyrophosphate link. An attempt to use an activated glycosyl phosphate failed 311 the only product identified from the reaction between /3-D-glucopyranosyl phosphoramidate (68) and uridine 5 -phosphate was the cyclic phosphate 69. The ease of participation of the sterically accessible, C-2 hydroxyl group probably accounts for this result. The usual procedure... 

A related method, of preparative value, was subsequently developed.323 It makes use of the 2-hydroxypyridyl esters (74), of nucleoside 5 -phosphates, which can readily be obtained from nucleoside 5 -phosphates and 2-pyridinol. The reaction of the derivative (74) with glycosyl phosphates in anhydrous pyridine gives rise to the... 

Several chemical and enzymatic methods are available for the synthesis of glycosyl phosphates. The required nucleoside triphosphates (NTPs) are most conveniently prepared by enzymatic routes. In general, these methods involve the sequential use of two kinases to transform NMPs to NTPs, by the corresponding NDPs (Fig. 2, see a recent review [12] for more details). 

In abbreviations for polyprenyl glycosyl phosphates, p stands for phosphate, and pp" for diphosphate groups. The abbreviation Bpr means a bacterial undecaprenyl group. For the moraprenyl group (see Ref. 57), the abbreviation Mpr is used, and the symbol Pre stands for any unidentified, lipid acceptor having the properties of polyprenol. 

For the study of polyprenyl glycosyl phosphates as intermediates in the synthesis of complex glycans, several techniques have been developed, and these have been described elsewhere in detail.18 20 Two important features should be emphasized. First, the very small amounts of polyprenyl phosphates that are present in most tissues for this reason, the use of radioactive techniques for the detection of products is obligatory. Second, on account of the hydrophobic nature of these compounds, and as the enzymes involved in the reactions are membrane-bound, the use of detergents and organic solvents becomes necessary. 

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