Thiyl-Radical Reactions in Carbohydrate Chemistry: From Thiosugars to Glycoconjugate Synthesis

Thiyl-radical mediated reactions have been extensively investigated for the preparation of carbohydrate derivatives. Due to the mild reaction conditions, high yields and tolerance to a wide range of functional groups, these reactions are ideally suited to the preparation of bioconjugates including glycopeptides and glycoproteins. This microreview covers the various synthetic strategies that have been employed for the preparation of thiosugars, glycoconjugates and glycodendrimers, employing the carbohydrate unit as both the carrier of the thiyl radical and also as the acceptor. Both the inter- and intramolecular thiol-ene and -yne processes are presented and discussed. Future perspective and directions for this methodology in glycoscience are also examined.