A Base Promoted Synthesis of Indazolo[2,3-a]quinolines from Isatogens and 2-(2-Aminophenyl)acetonitriles

Abstract

A transition-metal-free, base-promoted one-pot cascade cyclization strategy has been developed for the construction of indazolo[2,3-a]quinolines utilizing isatogens and 2-(2-aminophenyl)acetonitriles as precursors. This protocol enables the simultaneous formation of C–C, C–N, and N–N bonds to access complex tetracyclic frameworks. Preliminary photophysical characterization reveals significant fluorescence emission, indicating that the compound possesses promising optical properties for further investigations. The synthetic utility of this protocol is further underscored by its application in the Rh-catalyzed construction of highly-fused polycyclic cinnolinium salts.