Synthesis of Cinnolines via Rh(III)-Catalyzed Annulation of N-Aryl Heterocycles with Vinylene Carbonate

The Rh(III)-catalyzed C−H annulation reactions of N-aryl indazolones or N-aryl phthalazinones with a vinylene carbonate is described herein. This transformation provides the rapid access to indazolocinnolines and phthalazinocinnolines as important assets towards the development of novel bioactive compounds. Intriguingly, a vinylene carbonate acts as a vinyl transfer agent to enable the [4+2] annulation reaction. This method is characterized by its simplicity, mild reaction conditions, and broad functional group tolerance.