Annulation of α-Diazo Sulfonium Salts with α-Vinylanilines via a Dicationic Intermediate toward Quinolines

作者：Ziqiang Zhang, Xing Li, Si-Fu Gao, Bao‐Gui Cai, Qiang‐Qiang Li, Jun Xuan · 发表于：Organic Letters · 年份：2025 · DOI：10.1021/acs.orglett.5c02541 · 被引用次数：6 · 研究领域：Cyclopropane Reaction Mechanisms、Catalytic C–H Functionalization Methods、Synthesis and Catalytic Reactions

α-Diazo sulfonium salts constitute a unique subclass of diazo reagents that integrate diazo and sulfonium functionalities within a single molecular scaffold. While their reactivity via carbene, radical, or carbyne intermediates has been extensively investigated, the synthetic utility of their proton-activated dicationic species remains largely unexplored. Herein, we report a Brønsted acid-promoted, metal-free annulation of α-diazo sulfonium salts with binucleophilic α-vinylanilines. This transformation proceeds through a protonation-induced polarity inversion at the diazo carbon, generating a dicationic intermediate bearing two electrophilic centers. Sequential intramolecular nucleophilic substitution of this intermediate enables efficient access to mono-, di-, and trisubstituted quinolines under mild conditions. This study showcases a rare example of dielectrophilic activation in diazo chemistry and establishes a complementary strategy for constructing heterocycles beyond conventional carbene-based pathways.