Recent Advances in Cross-Couplings of Functionalized Organozinc Reagents
Baosheng Wei, Paul Knochel
Abstract
Abstract Cross-couplings involving organozinc reagents usually require a Pd-catalyst (Negishi cross-coupling), however, uncatalyzed cross-couplings of zinc organometallics proceed well in the absence of transition-metal catalysts with reactive electrophiles such as benzal 1,1-diacetates, benzhydryl acetates, and iminium trifluoroacetates. Organozinc compounds also undergo C–N bond formation with O-benzoylhydroxylamines or organic azides in the presence of cobalt- or iron-catalysts. Highly diastereoselective and enantioselective cross-couplings can be readily performed with room-temperature configurationally stable alkylzinc species, producing diastereoselectively and enantiomerically enriched products. Finally, highly regioselective magnesiations of functionalized arenes and heteroarenes undergo Negishi (after transmetalation with ZnCl2) or Cu-catalyzed cross-couplings. 1 Introduction 2 Uncatalyzed Cross-Couplings of Organozinc Reagents with Highly Electrophilic Partners 3 Iron- and Cobalt-Catalyzed Aminations using Organozinc Reagents 4 Stereo- and Regioselective Cross-Couplings of Organozinc Reagents 5 Conclusion