摘要/Abstract
Smiles重排反应是有机合成中被广泛使用的人名反应之一, 是芳基化合物构建策略的一种独特方法. Smiles重排经历了近一个世纪的发展, 从传统的离子型Smiles反应、Truce-Smiles反应等, 发展到后期的自由基型Smiles重排, 这些进展极大地丰富了该反应在合成化学、材料化学等领域的应用. 近年来, 光催化氧化还原反应获得了广泛关注, 这一新颖催化模式高效利用光能, 能在温和的条件下产生自由基中间体, 实现了很多选择性反应. 过去的五年中, 化学家逐渐将这一催化模式应用到了Smiles重排反应中, 发展了一系列新颖、实用的合成方法. 本文对这些进展进行综述, 主要依据促进重排反应的自由基种类和成键类型进行分类.
关键词: 可见光催化, Smiles重排, 自由基重排
The intramolecular aromatic ring systems migration reactions, namely Smiles rearrangement is a powerful method for (hetero)aryl group functionalization. It can be employed as a complementary strategy to arene functionalization, and has found its broad applications in synthetic chemistry. After the initial documentation in 1894 this chemistry was intensively investigated by Smiles. In its classical pathway, the migration of aromatic ring system takes place ipso nucleophilic substitution. Accordingly, the migrating (hetero)aryl groups are highly electronic and steric-dependent. Moreover, as new reaction modes reported, advances have been made in the areas for arene C—C, C—N and C—O bond formation and radical triggered Smiles rearrangement has also enriched migrating units. Recently, there has been a rapid growth in the transformation induced by visible-light photocatalysis. Harnessing visible light as the energy source for chemical reactions usually serves as an environmentally benign alternative in comparison with classical radical pathway. Furthermore, photoredox-induced rearrangement represents a valuable and efficient approach for facilitating both the radical-based bond-cleaving and bond-forming events in a single step. It has become an effective tool for both synthesis and late stage modification of bio-active molecules. The last five years has witnessed many important advances in exploring photo-induced Smiles reactions, which make this classic reaction regained its attention. Significant progress has been made for expediting the generation of N-centered, C-centered and O-centered from a variety of precursors before single electron transfer rearrangement. This powerful synthetic platform for efficient promotes (hetero) aromatic group construction under mild reaction conditions, and has become a useful method for the synthesis and late stage functionalization of pharmaceutically interest products. In this perspective, we focus on visible light induced Smiles chemistry, which the major breakthroughs are classified based on migrating-induced radical species, and their synthetic applications are discussed briefly.
Key words: visible-light photocatalysis, Smiles rearrangement, radical rearrangement
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