DFT-Guided Photocatalytic C5-Selective Hydrodechlorination of 4,5-Dichloropyridazinones

and DIPEA, the reaction proceeds under mild conditions and tolerates a wide range of N2 substituents and functional groups. Mechanistic studies support a single-electron transfer pathway involving a C5-centered radical, with DFT calculations revealing that the inherently weaker C5-Cl bond (87.1 vs 89.1 kcal/mol) accounts for the selectivity, while kinetic control from neutral DIPEA dictates the reaction outcome.