Koenigs-Knorr synthesis /Glycosidation

Koenigs-Knorr Synthesis / Reaction / Method / Glycosidation... 

Scheme 1 1,2-tranj-glycoside synthesis by Koenigs-Knorr-type glycosidations, and 1,2-cis-glycosides by the halide ion catalyzed method. 

In relation to carbohydrate chemistry, the Koenigs-Knorr synthesis of glycosides involves the treatment of glycosyl halides with an alcohol or phenol in the presence of a heavy metal salt.267 Karrer268 discovered that reaction of silver salts of hydros acids could also be used and use of these reagents has been extended more recently. Numerous variations and improvements on the original method have now been reported, and silver oxide, silver carbonate or silver trifluoromethanesulfonate have since become the accepted standard reagents.267... 

The above, indirect, procedure for glycoside synthesis is the Koenigs-Knorr method. Glycosidation may be effected from monosaccharides directly by treatment with an alcohol in the presence of a mineral acid catalyst. For example, when a-D-galactose (13) is heated in methanolic solution containing 2 per cent of hydrogen chloride the thermodymanically more stable methyl a-D-galacto-pyranoside (14) (Expt 5.113) is formed preferentially, and may be isolated from the reaction product by crystallisation as the monohydrate. The less abundant /i-anomer may be recovered from the mother-liquors. 

Banoub, J., Bundle, D. R. 1,2-Orthoacetate intermediates in silver trifluoromethanesulfonate promoted Koenigs-Knorr synthesis of disaccharide glycosides. Can. J. Chem. 1979, 57, 2091-2097. 

Koenigs-Knorr synthesis. Formation of glycosides from acetylated glycosyl halides and alcohols or phenols in the presence of silver carbonate or silver oxide. The reaction proceeds with inversion of configuration. 

Koenigs-Knorr reaction (Section 25.6) A method for the synthesis of glycosides by reaction of an alcohol with a pyranosyl bromide. 

A number of glycosides were available to Fischer by way of the Koenigs-Knorr reaction and his own glycoside synthesis, which involves treatment of... 

R. R. Schmidt, New methods for the synthesis of glycosides and oligosaccharides. Are there alternatives to the Koenigs-Knorr method Angew. Chem. lnt. Ed. Engl. 25 212 (1986). 

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