Metal‐Free Site‐Selective Direct Oxidative Phosphorylation of Pyrazolones

Abstract A substrate‐controlled site‐selective phosphorylation of pyrazolin‐5‐ones has been established under metal‐free direct oxidative coupling processes. A reaction between pyrazolones and secondary phosphonates in the presence of TBAI/TBHP combination could result in the N−P bond formation at N2 position. Meanwhile, the C−P bond coupling at C3 position could be obtained from a reaction of N2 ‐substituted pyrazolone substrates with secondary phosphine oxides using Selectfluor. These chemo‐ and regioselective metal‐free approaches proceed in fair to high yields under mild reaction conditions with good functional group compatibility. magnified image