Ru(II)-Catalyzed C-H Activation: Amide-Directed 1,4-Addition of the Ortho C-H Bond to Maleimides.

Maleimide has been used as a selective coupling partner to generate conjugate addition products exclusively. The typical Heck-type oxidative coupling that occurs when alkenes are used is avoided by choosing maleimide as an alkene, which cannot undergo β-hydride elimination due to the unavailability of a syn-periplanar β-hydrogen atom. The amide nitrogen, which is notorious for undergoing tandem reactions to generate spirocyclic or annulation products under cross-coupling conditions, remains innocent in this report. Along with the substrate scope, a robustness screen has been performed to analyze the performance of amide as a directing group in the presence of other directing groups and also to examine the tolerance of the reaction conditions for other frequently encountered functional groups.