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Synthesis 2025; 57(08): 1499-1505
DOI: 10.1055/a-2517-1556
paper

Metal-Free Photoinduced Cascade Cyclization of Alkyne-Tethered N-Alkoxybenzamides

Ximei Tang‡
a   School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, P. R. of China
b   College of Biological, Chemical Sciences and Engineering,Jiaxing University, Jiaxing 314001, Zhejiang, P. R. of China
,
Chen Baoc‡
b   College of Biological, Chemical Sciences and Engineering,Jiaxing University, Jiaxing 314001, Zhejiang, P. R. of China
,
Guang Cheng
b   College of Biological, Chemical Sciences and Engineering,Jiaxing University, Jiaxing 314001, Zhejiang, P. R. of China
,
Yuling Liao
b   College of Biological, Chemical Sciences and Engineering,Jiaxing University, Jiaxing 314001, Zhejiang, P. R. of China
,
Wenlin Xie∗
a   School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, P. R. of China
,
Guanyinsheng Qiu∗
b   College of Biological, Chemical Sciences and Engineering,Jiaxing University, Jiaxing 314001, Zhejiang, P. R. of China
› Author Affiliations
This work is supported by the Natural Science Foundation of Zhejiang Province (LQ22B020006), the Natural Science Foundation of Hunan Province (2024JJ7176), and the Scientific Research Fund of Hunan Provincial Education Department (22A0348).
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Abstract

In this work, a photoinduced synthesis of isoxazolidine-fused isoquinolin-1-ones and 3,4-dihydro[1,2]oxazino[2,3-b]isoquinolin-10(2H)-one from alkyne-tethered N-alkoxybenzamides is reported. The gram-scaled synthesis and structural elaboration of isoxazolidine-fused isoquinolin-1-ones are also realized. The reaction is promoted by an equimolar amount of tetrabutylammonium chloride, under metal- and catalyst-free conditions. In the reaction, it is believed that the alkyne-tethered N-alkoxybenzamide starting materials serve as photosensitizers, and the photoexcited substrate induces the formation of a chloro radical. The N-radical results from hydrogen atom abstraction by the chloro radical at the N–H bond of the substrates.

Key word

photoinduced - metal-free - N-radical - quinolin-1-ones - cascade cyclization

Supporting Information

    Supporting information for this article is available online at https://doi.org/10.1055/a-2517-1556.
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Publication History

Received: 17 December 2024

Accepted after revision: 15 January 2025

Accepted Manuscript online:
15 January 2025

Article published online:
10 March 2025

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