Synthesis of (2<i>H</i>)-Indazoles and Dihydrocinnolinones through Annulation of Azobenzenes with Vinylene Carbonate under Rh(III) Catalysis
Min Seo Park, Kyeongwon Moon, Harin Oh, Ji Yoon Lee, Prithwish Ghosh, Ju Young Kang, Jung Su Park, Neeraj Kumar Mishra, In Su Kim
Abstract
The Rh(III)-catalyzed C–H functionalization and subsequent intramolecular cyclization between azobenzenes and vinylene carbonate is described herein. Depending on the electronic property of azobenzenes, this transformation results in the formation of (2H)-indazoles or dihydrocinnolin-4-ones through the generation of ortho-alkylated azo-intermediates followed by decarboxylation. Surprisingly, vinylene carbonate acts as an acetaldehyde or acetyl surrogate to enable the [4 + 1] or [4 + 2] annulation reaction. This transformation is characterized by its mild reaction conditions, simplicity, and excellent functional group compatibility.