A simple and efficient procedure for the synthesis of pyridazin-3(2H)-ones through copper-catalyzeddehydrogenation of a single C–C bond of 4,5-dihydropyridazin-3(2H)-ones to a C=C bond with oxygen as the terminal oxidant is described. Functional groups including hydroxy, carboxylic, bromo, chloro, cyano, nitro and alkoxy were all tolerated under the reaction conditions. Moreover, this methodology
A copper‐catalyzed cascade dehydrogenative and dehalogenativereaction of halogenated 6‐phenyl‐4,5‐dihydropyridazin‐3(2H)‐ones to 6‐phenylpyridazin‐3(2H)‐ones has been developed. Moreover, the catalytic system consisting of copper(II) acetate/sodium carbonate/pyridine exhibits high reactivity and selectivity with oxygen as the terminal oxidant.