Visible-light driven synthesis of polycyclic benzo[<i>d</i>][1,3]oxazocine from 2-aminochalcone
Yu-Qi Gao, Yi Hou, Liming Zhu, Junhan Chen, Ruoxin Li, Shengyong Zhang, Yu‐Peng He, Weiqing Xie
Abstract
Herein, we report a tandem cycloisomerization/nucleophilic addition/cyclization of 2-amino chalcone with bifunctional nucleophiles driven by visible light. This cascade process is realized by the irradiation of a blue LED at room temperature, which provides a concise route to structurally diverse benzo[d][1,3]oxazocine scaffolds. Mechanistic studies show that the reaction is initiated with the E to Z isomerization of a C-C double bond upon the irradiation of visible light, followed by cyclization/rearomatization to generate a transient quinolinium intermediate, which is trapped by the nucleophile and cyclized to produce the polycyclic benzo[d][1,3]oxazocine.