Rh(III)-Catalyzed Synthesis of Indazolo[2,3‑<i>a</i>]quinolines: Vinylene Carbonate as C1 and C2 Building Blocks

Abstract

A rhodium-catalyzed cyclization of azobenzenes and vinylene carbonate via C–H bond activation to construct indazolo­[2,3-a]­quinolines has been developed. This protocol offers an efficient method for synthesis of the titled products in good yields with broad functional group tolerance. In this reaction, three C–C bonds and C–N bond are formed in one pot, and vinylene carbonate (VC) acts as C1 and C2 synthons as well as “vinylene transfer” agent and acylation reagent in the construction of target-fused heterocycles. Moreover, the products exhibit favorable fluorescence properties, which indicate their potential application as fluorescent materials and biosensors