Synthesis of Pyrroloquinazolinones via Base-Promoted Domino Reaction of 7-Vinylindoles with In Situ Formed Isocyanates from Dioxazolones.

Herein, we report a novel base-promoted domino reaction between 7-vinylindoles and dioxazolones, enabling the efficient one-pot synthesis of pyrroloquinazolinone scaffolds in moderate to excellent yields (up to 95%). This transition-metal-free protocol employs readily available dioxazolones as isocyanate precursors and proceeds through a cascade sequence involving decarboxylation, Lossen rearrangement, nucleophilic addition, and aza-Michael addition. Through this cascade process, complex polycyclic indole-based scaffolds are efficiently constructed in a single operation. The established methodology features operational simplicity, broad substrate scope, scalability to gram-scale synthesis, and potential for late-stage functionalization.