Metal-Free Direct Alkylation of Ketene Dithioacetals by Oxidative C(sp2 )-H/C(sp3 )-H Cross-Coupling.

The functionalization of internal olefins has been a challenging task in organic synthesis. This protocol provides an efficient and transition-metal-free direct oxidative C(sp2 )-H/C(sp3 )-H cross-coupling method to access tetrasubstituted olefins. The push-pull effect from the polarized olefin substrates accelerates the internal olefin C-H alkylation. Importantly, the mechanistic experimental results demonstrate that the alkanes C-H bond cleavage is the rate-determining step, and a radical pathway has been proposed for the alkylation reaction. Notably, the present protocol has excellent functional group tolerance and could be easily scaled up with good efficiency.