Cross-electrophile coupling (XEC) of aryl bromides with alkyl bromides has become a powerful method for the synthesis of carbon-carbon bonds. Despite their utility, the requirement of selective aryl halide activation over alkyl halides has limited the coupling partners for these methods . This limits XEC reactions to electron-deficient aryl halides being coupled with more difficult alkyl halides (1°&gt;2°) and generally excludes tertiary electrophiles. This work details the identification of an electroreductive, dual ligand system that enables highly selective activation of electron-rich aryl halides over 3° alkyl halides. Detailed mechanistic studies implicate the generation of a low-valent L<sub>2</sub>(Ni<sup>0</sup>) that is critical to selective aryl electrophile activation. Furthermore, our studies suggest the ligands operate in a cooperative fashion such that the P,N ligand enables oxidative addition of aryl halides while a tridentate ligand stabilizes Ni(II)-Ar for radical capture. In addition to selective XEC of tertiary alkyl halides, we generalized this strategy toward the XEC of traditionally inaccessible aryl electrophiles from aryl chlorides to aryl/vinyl triflates with secondary alkyl bromides.

Highly selective cross-electrophile coupling enabled by dual catalyst system

ACS Spring 2022

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