Selenium-Catalyzed Oxidative C–H Amination of (<i>E</i>)‑3-(Arylamino)-2-styrylquinazolin-4(3<i>H</i>)‑ones: A Metal-Free Synthesis of 1,2-Diarylpyrazolo[5,1‑<i>b</i>]quinazolin-9(1<i>H</i>)‑ones

A novel metal-free catalysis protocol for the synthesis of 1,2-diarylpyrazolo­[5,1-b]­quinazolin-9­(1H)-ones via intramolecular oxidative C–H amination of (E)-3-(arylamino)-2-styrylquinazolin-4­(3H)-ones has been developed in moderate to good yield. The method shows good functional group tolerance. The presented approach offers a new synthetic pathway toward the core structures of 2,3-fused quinazolinones. Moreover, the present synthetic route can be readily scaled up to gram quantity without difficulty. A possible mechanism involves a seleniranium ion followed by three-membered ring opening to form the C–N bond.