Hypervalent iodine(III)-mediated oxidative dearomatization of 2 H -indazoles towards indazolyl indazolones.

A new iodine(III)-mediated oxidative dearomatization of 2 H -indazoles has been developed to afford N -1 indazolyl indazolones. In this methodology, PIFA plays a dual role: as an oxidant and as a carbonyl oxygen source. A series of indazolone derivatives was promptly synthesized in good to excellent yields through sequential C-heteroatom bond formation. Mechanistic studies indicate that the reaction likely takes place through an SET pathway.