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.