Iron-Enhanced Reactivity of Radicals Enables C–H Tertiary Alkylations for Construction of Functionalized Quaternary Carbons

Iron is one of the most attractive catalysts, especially for aromatic C–H functionalizations. However, stoichiometric amounts of oxidants and strong carbanions are required, and C–H tertiary alkylation, especially with electron-deficient alkyl groups, is unexplored. In this paper, we describe the development of iron-catalyzed selective C–H tertiary alkylations with heteroaromatics, in which an iron salt acts as a single-electron source and enhances the reactivity of a tertiary alkyl radical generated from α-bromocarbonyl compounds. Our established methodology was demonstrated in the efficient synthesis of various quaternary carbon atoms under very simple conditions.