Glycopyranosyl fluoride

Noyori and coworkers found that tetrafluorosilane or trimethylsilyl tri-flate catalyzes the condensation of appropriately protected glycopyranosyl fluorides with trimethylsilyl ethers or alcohols. The strong affinity of silicon for fluorine was considered to be the driving force for this reaction. In the case of Sip4, attack of a nucleophile on the glycosyl cation-SiFj ion-pair intermediate was anticipated. Thus, condensation of 2,3,4,6-tetra-O-benzyl-a- and - -D-glucopyranosyl fluorides (47a and 47fi) with methyl... 

The signs of geminal, F H coupling-constants (in contrast to those of geminal, iH-1H coupling-constants) are absolutely positive. They were determined for derivatives of glycopyranosyl fluorides, 75,292,293 2-deoxy-2-fluoro-D-gluco- and -manno-pyranosyl fluorides,71... 

In a study of the infrared spectra of acetylated and benzoylated gly-copyranosyl fluorides, it was found that, with few exceptions, such compounds exhibit an absorption band at 802-748 cm-1 if the fluorine atom is axial, whereas no such absorption band is observed if the fluorine atom is equatorial therefore, it is necessary to know the conformation of the molecule before the anomeric configuration can thus be determined.45 It is possible that reinterpretation of some of these observed absorptions may be necessary, because some of the conformations of some of the glycopyranosyl fluorides are now known to exist in the conformation opposite to that originally anticipated without proof, because of the strong anomeric effect of a fluorine substituent (see Section III,2e). 

Glycosidation.1 These gallium compounds serve as efficient activators for gly-cosidation of glycopyranosyl fluorides in CH2C12 or toluene with moderate p-selec-tivity. 

A method using silver(I) fluoride and chlorine is sufficiently mild for the isolation of the chlorine fluoride adducts in good yield, whereas the combination of IV-chlorosuccinimide and hydrogen fluoride gives no fluorinated products. The reaction of chlorine with a suspension of D-glucal triacetate and silver(I) fluoride in an acetonitrile/benzene solution is unusual in that it gives all four possible 3,4,6-tri-0-acetyl-2-chloro-2-deoxy-D-glycopyranosyl fluorides... 

Mukaiyama T, Murai Y, Shoda S. An efficient method for glu-cosylation of hydroxy compotmds using glycopyranosyl fluoride. Chem. Lett. 1981 3 431-432. 

Takeuchi, K, Mukaiyama, T, Trityl tetrakis(pentafluorophenyl)borate catalyzed stereoselective glycosylation using glycopyranosyl fluoride as a glycosyl donor, Chem. Lett, 555-556, 1998. 

Coupling 2-diethylalumino-l-methylpyrrole (163) with a-o-glycofurano-syl fluorides (162) afforded the corresponding pyrrol-2-yl C-nucleosides 164, which retained the configuration of the anomeric center of the starting fluoride. /3-o-Glycopyranosyl fluorides behaved similarly (88JOC3371) (Scheme 30). 

I. Lundt, C. Pedersen, Infrared spectra of acetylated and benzoylated glycopyranosyl fluorides, Mikrochim. Acta, (1966) 126-132. 

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