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.