Reactivity of (bi-Oxazoline)organonickel Complexes and Revision of a Catalytic Mechanism

J Am Chem Soc. 2021 Sep 15;143(36):14458-14463. doi: 10.1021/jacs.1c07139. Epub 2021 Aug 31.

Abstract

Bi-Oxazoline (biOx) has emerged as an effective ligand framework for promoting nickel-catalyzed cross-coupling, cross-electrophile coupling, and photoredox-nickel dual catalytic reactions. This report fills the knowledge gap of the organometallic reactivity of (biOx)Ni complexes, including catalyst reduction, oxidative electrophile activation, radical capture, and reductive elimination. The biOx ligand displays no redox activity in (biOx)Ni(I) complexes, in contrast to other chelating imine and oxazoline ligands. The lack of ligand redox activity results in more negative reduction potentials of (biOx)Ni(II) complexes and accounts for the inability of zinc and manganese to reduce (biOx)Ni(II) species. On the basis of these results, we revise the formerly proposed "sequential reduction" mechanism of a (biOx)Ni-catalyzed cross-electrophile coupling reaction by excluding catalyst reduction steps.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, Non-U.S. Gov't