Ru-catalyzed room-temperature alkylation and late-stage alkylation of arenes with primary alkyl bromides

Summary The C–H alkylation of arenes with N-based directing groups typically requires high temperatures and/or harsh reaction conditions, which has traditionally reduced its functional group compatibility and applicability for late-stage functionalization. We report that a cyclometallated Ru complex is able to perform the C–H alkylation of arenes bearing a variety of N-directing groups with primary alkyl bromides at room temperature and under mild reaction conditions. We demonstrate this with an extended substrate scope, which includes several examples of late-stage alkylation of drug molecules, thus showcasing the “real-world” capabilities of this method. Mechanistic studies show that, in contrast to previous mechanistic proposals, the reaction proceeds via a bis-cyclometallated Ru intermediate, followed by an SN2-type oxidative addition.