ABSTRACT
The most common method for carbon-carbon bond formation at the anomeric carbon involves nucleophilic attack on the naturally electrophilic center. A wide variety of electrophilic sugars have been employed, such as reducing sugars, alkyl glycosides, anomeric esters, anomeric trichloroacetimidates, and glycosyl halides. The reaction is useful since it provides quick access to the 2-deoxy aryl C-glycosides which are found in many naturally occurring aryl C-glycosides. Kishi, Lewis, and Cha have developed methodology for the convenient access to a-C-glycosides from anomeric p-nitrobenzoates, which are themselves available from the free sugar. Glycosyl halides have been used fairly extensively in C-glycoside preparation. Anomeric chlorides, bromides, and fluorides have all received significant synthetic attention. Glycosyl bromides have also seen use in the synthesis of C-glycosides since they are fairly reactive species as well as readily available intermediates. Hurd and Bonner were the first to condense Grignard reagents with pyranosyl bromides to obtain C-glycosides.
