On the Strategic Impact of the Degenerative Transfer of Xanthates on Synthetic Planning

The present brief account relates synthetic endeavours revolving around a novel chemistry of xanthates (dithiocarbonates) being developed in our group. The degenerative reversible transfer of xanthates has a unique ability to store reactive radicals in a dormant form, and thereby to enhance their lifetime in a concentrated medium, while at the same time, regulating their absolute and relative concentrations. It allows intermolecular radical additions even to unactivated alkenes, and can promote otherwise sluggish radical processes, such as 5-endo, 6-exo, 6-endo, 7-endo, and 8-endo cyclisations, as well as ring closures on (hetero)aromatic structures. This chemistry has proved remarkably versatile and powerful, both for solving synthetic problems and for the industrial production of block copolymers through the RAFT/MADIX technology.