中国海洋大学王洪玉研究团队报道了基于底物-光敏策略的可见光诱导极性转换合成3,3-二取代吲哚。相关研究成果发表咋2024年11月25日出版的《中国化学》。

3,3-二取代羟吲哚是广泛的生物活性天然产物和药物的核心，人们为开发有效的制备方法付出了巨大的努力。

该文中，研究人员成功开发了一种在可见光下，通过底物光敏策略合成3,3-二取代吲哚的无光催化剂方法。

初步的机理研究表明，靛红衍生的亚胺可以直接被可见光激发，产生强氧化态，促进随后与Hantzsch酯的单电子转移（SET）过程，从而提供相应的α-氨基中间体。

因此，这些α-氨基自由基促进了随后的Giese自由基加成，或自由基/自由基交叉偶联反应，以高产率提供各种官能化的3-取代3-氨基羟吲哚。

附：英文原文

Title: Visible Light-Induced Umpolung Synthesis of 3,3-Disubstituted Oxindoles via the Substrate-Photosensitive Strategy

Author: Jingjing Yang, Tingting Wang, Benhui Sui, Hongyu Wang, Bo Tang

Issue&Volume: 2024-11-25

Abstract: 3,3-Disubstituted oxindoles, forming the core of extensive bioactive natural products and drugs, attract tremendous efforts to develop efficient methods for their preparation. Here, a photocatalyst-free approach for the synthesis of 3,3-disubstituted oxindoles via a substrate-photosensitive strategy under visible light was successfully developed. Preliminary mechanistic studies illustrated that isatin-derived imines can be directly excited by visible light to generate strong oxidant states, facilitating subsequent single-electron transfer (SET) processes with Hantzsch esters to afford the corresponding α-amino radical intermediates. Thus, these α-amino radicals promote the subsequent Giese radical addition or radical/radical cross-coupling reactions to furnish diverse functionalized 3-substituted 3-aminooxindoles in high yields.

DOI: 10.1002/cjoc.202400973

Source: https://onlinelibrary.wiley.com/doi/full/10.1002/cjoc.202400973