C–H Activation of Diphenyldiazomethane at a Ni(0) Center Assisted by a Lewis Acidic Secondary Coordination Sphere

Abstract We report the synthesis of two bidentate phosphine ligands functionalized with Lewis acidic pendant groups, namely L1 bearing two BCy2 groups and L2 bearing two BBN groups. The corresponding Ni(0)-olefin complexes react with diphenyldiazomethane (Ph2CN2) to form formal Ni(0)-diazo complexes. Whereas the diazo complex bearing BCy2 groups is stable at room temperature, the BBN-bearing analogue undergoes C–H activation of the diazo ligand with retention of the N2 moiety to afford a Ni(II) arylamido complex. This complex participates in an oxidatively induced reductive elimination to afford an indazole derivative, while reaction with π-acceptor ligands such as CO or isocyanides gives phthalazine derivatives. This work establishes guiding principles for catalyst design by highlighting the role of secondary interactions in enabling unique transformations and stabilizing key intermediates.