Ir(III) Pincer Complex with Solo Coordinatively Active Site as a Surrogate for Half-Sandwich Catalysts: Enabling Asymmetric Acylnitrenoid Transfer and Structure–Activity Relationship Studies

Metal-acylnitrenoid-enabled asymmetric C(sp³)-H amidation has emerged as a highly effective synthetic strategy for accessing enantioenriched amides and chiral amines. While state-of-the-art transition metal catalysts typically feature a half-sandwich scaffold, the exploration of novel catalyst scaffolds remains intriguing. We herein introduce a new class of Ir(III) pincer complexes, which exhibit exceptional modularity and tunability in both steric and electronic properties. They have been demonstrated to function as highly efficient precatalysts (with loadings as low as 0.01 mol %) for C(sp³)-H amidation, enabling the synthesis of enantioenriched γ-lactams and octahydroindole derivatives. The remarkable robustness of these iridium complexes has been confirmed through treatments with strong acid and base, as well as heating and catalyst recovery experiments. Structure-activity relationship studies provided valuable insights into the underlying mechanisms driving the success of these Ir(III) complexes.