The Koenigs-Knorr and Related Methods

In 1901, Koenigs and Knorr published an efficient method for the preparation of alkyl and aryl O-glycosides [89]. The Koenigs-Knorr reaction has for a long time been the best method achievable for the synthesis of O-glycosides. This method has been widely studied and improved in the years [31,90,91], and although valuable alternatives are now established, it still is the method of choice when more sophisticated procedures fail. 

In the Koenigs-Knorr method, glycosyl halides are the glycosyl donors. The procedure consists of the treatment of glycosyl bromides or chlorides, easily obtained as pure a anomers [3], with alcoholic or phenolic acceptors in the presence of an excess of a heavy metal salt [92], Silver carbonate or silver oxide were originally used, but at present silver triflate or mercury (II) salts are the most frequently promoters employed [93]. 

8 Selective Glycosidation Reactions and Their Use in Medicinal Chemistry 

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