The Tandem C–H/N–H Activation of <i>N</i>‑Methyl Arylamide Catalyzed by Dinuclear Pd(II) Benzhydrazone Complex: A Concise Access to Phenanthridinone

A direct and efficient strategy for the synthesis of phenanthridinone from the coupling of N-methyl benzamide and aryl boronic acid via C–C/​C–N bond formation catalyzed by a newly synthesized dinuclear palladium­(II) complex has been reported. The unprecedented formation of the dinuclear palladium­(II) hydrazone complex was fully characterized, and the molecular structure of the complex was studied by a single-crystal X-ray method. A diverse range of phenanthridinones were synthesized in good to excellent yields in an open atmosphere with 1 mol % catalyst loading under additive- or oxidant-free condition. The excellent yields achieved by the titled catalyst would constitute the forefront of a mild, green synthetic prowess for phenanthridinone formation. Moreover, the effect of various reaction parameters like solvents, bases, and catalyst loadings has been studied. Gratifyingly, the successful isolation of the intermediate would suggest that the catalytic reaction proceeds via ortho-arylation