Palladium‐Catalysed C−H Bond Zincation of Arenes: Scope, Mechanism, and the Role of Heterometallic Intermediates

Catalytic methods that transform C−H bonds into C−X bonds are of paramount importance in synthesis. A particular focus has been the generation of organoboranes, organosilanes and organostannanes from simple hydrocarbons (X=B, Si, Sn). Despite the importance of organozinc compounds (X=Zn), their synthesis by the catalytic functionalisation of C−H bonds remains unknown. Herein, we show that a palladium catalyst and zinc hydride reagent can be used to transform C−H bonds into C−Zn bonds. The new catalytic C−H zincation protocol has been applied to a variety of arenes—including fluoroarenes, heteroarenes, and benzene—with high chemo‐ and regioselectivity. A mechanistic study shows that heterometallic Pd–Zn complexes play a key role in catalysis. The conclusions of this work are twofold; the first is that valuable organozinc compounds are finally accessible by catalytic C−H functionalisation, the second is that heterometallic complexes are intimately involved in bond‐making and bond‐breaking steps of C−H functionalisation. A palladium catalyst and zinc hydride reagent can be used to transform C−H bonds into C−Zn bonds. The reaction scope includes fluoroarenes, heteroarenes, and benzene. Heterometallic Pd–Zn complexes play a key role in the catalysis.