Synthesis of Heterocycles from Glycosylamines and Glycosyl Azides

Abstract

Glycosylamines and glycosyl azides are valuable and versatile intermediates in carbohydrate chemistry; furthermore they are easily available in a highly stereoselective fashion. Glycosylamines and their derivatives glycosyl enamines and glycosyl imines can be transformed into N-glycosyl heterocycles. Glycosyl enamines are also used in the preparation of polyhydroxy pyrrolidines, oxapyrrolizidines, piperidines and azepanes, an intramolecular nucleophilic displacement of a sulfonyloxy group by a stabilized amide anion being the key step. Glycosyl azides can be converted into a plethora of heterocyclic derivatives by different reactions such as the Staudinger reaction, thermolysis and 1,3-dipolar cycloadditions. Much effort has been devoted to the synthesis of glycosyl triazoles by using the Dimroth reaction, ketene aminals, phosphorus ylides, azide–alkyne Huisgen cycloaddition and the especially successful Cu(I)-mediated Huisgen cycloaddition.