Glycosyl sulfonates glycoside synthesis

Our strategy for the Smij-promoted synthesis of l,2-cis-C-glycosides is illustrated in Figure 3. It was assumed that one-electron transfer to the LUMO of the aryl sulfone group in A would result in concomitant cleavage of the C1 -S bond liberating an anomeric radical intermediate, as previously observed in the reductive lithiation of glycosyl phenyl sulfones." If 5-exo cyclization onto the silicon-tethered alkene/alkyne is substantially favored over a second electron transfer from Smij, then the exocyclic carbon radical B would ultimately be formed. On the other hand, reduction of the Cl-radical by... 

Inversion of configuration (cf Epimerization) of alcohols (Mitsunobu reaction), 160-161, 286 of ally lie acetates with Pd, 27, 164 of allylpalladium with d-synthons, 27, 264 of alkyl halides or sulfonates by 1,3-dithiane anions, 22 by organylcuprates, 36 by tetracarbonylferrate<2 -X 46-47 in triorganylborane rearr., 37-38 of glycosides with free 2-OH by DAST, 272 of glycosyl halides, 271 of oxiranes by 1-alkync anions, 64, 204 by enolate type anions, 63-64 by internal alcoholate addition, 265 Inversion-esterification of alcohols, 160-161, 286 Inverted DNA , 345-346 Iodide, hydrogen porphyrin synthesis with, 255 Iodine = diiodine (Ij) ... 

The benzyl-protected mannosyl a-trichloroacetimidate has been used for the gly-cosylation of 2-mercaptopyridine (Scheme 50) [207], but the stereoselectivity was low. The P-glycoside was separated and oxidized to Ae 2-pyridyl sulfone which was employed as glycosyl donor for the synthesis of C-glycosides. The corresponding azidogalactose and 7V-acetylgalactosamine derivatives have also been prepared [208],... 

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