Cobalt-Bisoxazoline-Catalyzed Enantioselective Cross-Coupling of α-Bromo Esters with Alkenyl Grignard Reagents.

The first catalytic asymmetric Kumada cross-coupling of organic halides with alkenyl Grignard reagents has been developed. The reaction was promoted by the cobalt-bisoxazoline catalyst and afforded various α-alkyl-β,γ-unsaturated esters with excellent enantioselectivities and moderate to good yields (≤95% ee and ≤82% yields). The formal synthesis of the California red scale pheromone using this method was investigated, and radical clock experiments were performed.