A Radical Route to α-Substituted Enones.

A versatile strategy for the α-substitution of enones through the formal fusion between enones and unactivated alkenes is described. It relies on the formation and use of α-xanthyl-β-hydroxy ketones, which can be considered as synthetic equivalents of the high energy and difficult to tame alkenyl radicals. This approach thus constitutes a solution to the long-standing problem of sp2-sp3 bond formation in the α-position of enones and complements metal based methods that are more suitable for sp2-sp2 and sp2 -sp couplings. The functional group tolerance is particularly broad and the process, which can often be accomplished one-pot, could be extended in one case to an α,β-unsaturated ester.