Expanding the Potential of 3‐Hydroxyindolinones: Synthesis of Quinoxalin‐2(1H)‐ones through Acid‐Promoted Azidation and Ring‐Expansion

Abstract

AbstractWe report herein a synthesis of quinoxalin‐2(1H)‐ones from 3‐hydroxyindolin‐2‐one derivatives, which can be synthesized from commercially available isatins in one or two steps. The reaction proceeded through a CF3CO2H‐mediated azidation via a carbocation, followed by acid‐induced N2 extrusion and ring‐expansion. Both CF3CO2H and the solvent 1,1,1,3,3,3‐hexafluoro‐2‐propanol were found to be crucial for this rearrangement. The axial chirality in 3‐hydroxyindolin‐2‐one skeleton was fully preserved in the products.