Glycosidation, silver-assisted

This method of silver-assisted glycoside synthesis is a variation of the Koenigs-Knorr reaction, which uses silver carbonate. William Koenigs and Edward Knorr first reported their method in 1901. 

Condensation [274] of the bromide (412) with the unsaturated derivative (378) using silver triflate gave an a p yield ratio of 42 21% and condensation of (412) with (377) gave 26 8%. From these results the authors concluded that the 3-P-hy-droxyl group on the neuraminic acid halide prevents dehydrohalogenation and assists glycosidation. 

Garegg, P J, Johansson, R, Samuelsson, B, Silver imidazolate-assisted glycosidations. Part 6. Synthesis of 1,2-rranj-linked disaccharides, Acta Chem. Scand. B, 36, 249-250, 1982. 

S-Glycosides. Thioglycosides can be prepared from glycosyl bromides by reaction with /3-trimethylsilyIethyl sulfides in the presence of AgBp4. The silver salt provides Ag to assist ionization of the halogen, and also a F to initiate removal of the silylethyl group of the intermediately formed glycosylsulfonium salts. 

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