Pragmatic Access to Hybrid Quinoxaline Scaffold Mediated by Elemental Sulfur Enabling Actualization to π‑Extended and Aza-Annulated Heterocyclic Units

A metal-free approach for synthesizing hybrid quinoxaline
derivatives
from sulfoxonium ylide and a 1,5-bis-nucleophilic N-heterocycle mediated
by elemental sulfur is presented to illuminate the [5+1] cascade cyclization
sequence. Large-scale synthesis and postsynthetic functionalizations
for the annulative π-extension and intramolecular aza-annulation
reactions reveal the potential utility and actualize the fabricated
approach.