Visible-Light-Mediated Skeletal Editing of Furans to Pyridazines

We herein describe a visible-light-mediated skeletal editing of furans to pyridazines via formal O-to-NN atom-pair exchange using hydrazine hydrate. The reaction proceeds under metal-free conditions at room temperature in air, providing di-, tri-, and tetrasubstituted pyridazines with complete regiocontrol from readily available furans. Broad functional-group tolerance, gram-scale synthesis, and late-stage skeletal editing of complex molecules are demonstrated. Mechanistic studies suggest that water suppresses hydrazine-mediated quenching of the excited photocatalyst, while additional experiments support the involvement of oxygen-derived reactive species in the overall transformation.