Structural And Electronic Control Of The Bidentate 1-(2-Pyridyl)Benzotriazole Ligand In Copper Chemistry With Application To Catalysis In The A(3) Coupling Reaction

The hybrid bidentate 1-(2-pyridyl)benzotriazole (pyb) ligand was introduced into 3d transition metal catalysis. Specifically, [Cu-II(OTf)(2)(pyb)(2)].2 CH3CN (1) enables the synthesis of a wide range of propargylamines by the A(3) coupling reaction at room temperature in the absence of additives. Experimental and high-level theoretical calculations suggest that the bridging N atom of the ligand imposes exclusive trans coordination at Cu and allows ligand rotation, while the N atom of the pyridine group modulates charge distribution and flux, and thus orchestrates structural and electronic precatalyst control permitting alkyne binding with simultaneous activation of the C-H bond via a transient Cu-I species.