Cu(I)-Catalyzed C-H Alkenylation of Tertiary C(sp)-H Bonds of 3-Aryl Benzofuran-2()-ones to Give - and -Styrene Containing Quaternary Carbon Centers with 99/1 Regioselectivity.

The synthesis of isomerically pure olefins containing all-carbon quaternary centers is a challenging issue. Herein, we developed an efficient protocol for the synthesis of ()-olefins (27 examples, yield up to 97%, / up to 99/1) and ()-olefins (16 examples, yield up to 94%, / up to 99/1) containing all-carbon quaternary centers. This protocol is adopted for the copper-catalyzed regioselective C-H alkenylation of the tertiary C(sp)-H bond of 3-aryl benzofuran-2()-ones with alkyne and alkenes. A diverse range of functional groups in the substrates is well-tolerated, such as F, Cl, Br, Me, OMe, ester, CF, etc. A gram scale experiment was performed in good yield, and the radical mechanisms are also proposed based on the control experiments.