Oxidative Cross-Coupling of Trans -1,2-Dizincioalkenes With Alkylzincs Through Pd/Zn Ligand-Scrambling

Abstract 1,2-Dimetalloalkenes are versatile precursors for the stereoselective synthesis of multi-substituted alkenes. We have recently reported the reductive anti-dizincation of alkynes using sodium metal and zinc chloride. Here we report that trans-1,2-dizincioalkenes underwent a palladium-catalyzed oxidative cross-coupling with alkylzincs with the aid of 2,4,6-trimethoxyiodobenzene to yield anti-1,2-dialkylated alkenes stereoselectively. Mechanistic investigations suggest that the catalytic cycle involves a palladium-zinc ligand-scrambling process between organopalladium and organozinc species and subsequent reductive elimination to form an alkenyl-alkyl bond.