Electrochemical\nSynthesis of an <i>N</i>‑Arylpyridazinone: Discovery\nand Scale-Up

An electrochemical NH/CH-coupling of a functionalized\npyridazinone\nwith veratrole was developed to create the central C–N bond\nof an agrochemical intermediate. Electrolysis was performed in methanol\nusing potassium pivalate, which served a dual role as both a mild\ncatalytic base and a supporting electrolyte; H<sub>2</sub> is generated\nas the sole stoichiometric byproduct. Mechanistic studies suggest\nthe formation of a <i>N</i>-centered radical on the pyridazinone\nnitrogen that adds to the veratrole pi-system; closure of the catalytic\ncycle involves further one-electron oxidation and deprotonation. Initial\noptimization in a batch electrochemical cell was followed by optimization\nof a loop-flow process that provided significant yield improvements\nfrom batch. The loop-flow electrochemical process was successfully\nscaled to a reaction volume of 2 L.