Catalytic Coupling between Unactivated Aliphatic C–H Bonds and Alkynes via a Metal–Hydride Pathway

We report a Rh­(I)-catalyzed site-selective coupling between ketone β-C­(sp3)–H bonds and aliphatic alkynes using an in situ-installed directing group. Upon hydrogenation or hydration, various β-alkylation or β-aldol products of the ketones are obtained with broad functional group tolerance. Mechanistic investigations support the involvement of a Rh–H intermediate through oxidative addition of Rh­(I) into the β-C–H bonds. Thus, to the best of our knowledge, this transformation represents the first example of catalytic couplings between unsaturated hydrocarbons and unactivated aliphatic C–H bonds via a metal–hydride pathway.