Annulative Coupling of o -Phenylenediamine and Diazo Esters: Access to 3-Arylquinoxaline-2-ones

-phenylenediamines for the synthesis of 3-arylquinoxalin-2-ones. The transformation proceeds through a cascade process involving sequential C-N bond formations under metal-free conditions, delivering a diverse range of quinoxalin-2-one derivatives in moderate to good yields. The protocol features operational simplicity, mild reaction conditions, and broad functional group tolerance across both diazo esters and diamine partners. Its practicality is demonstrated by gram-scale synthesis and further highlighted through late-stage functionalization, including triflation followed by Sonogashira coupling, as well as thionation to access key precursors of bioactive molecules.