Stereoselective photochemical transformations of hexopyranosyl imides to highly functionalised heterocycles

Abstract

Reaction of O-protected glycosylamines with succinic anhydride and subsequent acylation afford both anomers of gluco- and manno-configurated N-glycosylsuccinimides. Irradiation with UV light of 254 nm wavelength leads to abstraction of H-2 and H-5, respectively, by the excited carbonyl function. The stereoselective recombination of the resulting 1,4- and 1,5-diradicals gives the annelated azacyclobutanol and azacyclopentanol derivatives, respectively. Owing to the strained four-membered rings, the azacyclobutanol derivatives fragment by an aza-analogous retroaldol addition to give the hexopyranosyl-annelated azepanedione systems.