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

摘要

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 alpha-bromocarbonyl compounds. Our established methodology was demonstrated in the efficient synthesis of various quaternary carbon atoms under very simple conditions.