Synergistic Bimetallic Ni/Ag and Ni/Cu Catalysis for Regioselective γ,δ-Diarylation of Alkenyl Ketimines: Addressing β‑H Elimination by in Situ Generation of Cationic Ni(II) Catalysts

We disclose unprecedented
synergistic bimetallic Ni/Ag and Ni/Cu
catalysts for regioselective γ,δ-diarylation of unactivated
alkenes in simple ketimines with aryl halides and arylzinc reagents.
The bimetallic synergy, which generates cationic Ni­(II) species during
reaction, promotes migratory insertion and transmetalation steps and
suppresses β-H elimination and cross-coupling, the major side
reactions that cause serious problems during alkene difunctionalization.
This diarylation reaction proceeds at remote locations to imines to
afford, after simple H+ workup, diversely substituted γ,δ-diaryl
ketones that are otherwise difficult to access readily with existing
methods.