Electrochemically-induced regioselective cyclization of N-methacryloyl hydrazones: efficient synthesis of phosphorylated pyrazolone derivatives.

An electrochemically driven redox strategy has been developed for the regioselective synthesis of phosphorus-containing 2-pyrazolin-5-ones via radical addition-cyclization cascades. This metal-free protocol enables the efficient incorporation of symmetrical phosphoryl radicals into N-methacryloyl hydrazones under mild conditions. The protocol demonstrates broad substrate scope. Various control experiments explored the merits and the plausible mechanism of the electrochemical phosphorylation systems. This work provides a sustainable and versatile approach to phosphorus-containing heterocycles, holding promise for applications in medicinal chemistry.