Aryl radicals are important intermediates in organic synthesis. The generation of these reactive species via direct decarboxylation of inexpensive and readily available aromatic carboxylic acids is an attractive goal. However, such a process intrinsically exhibits high energy barriers to overcome, which in consequence usually require precious metal catalysis, stoichiometric oxidants and harsh conditions, suffering from limitations such as poor functional group tolerance and low atom economy. In recent years, photochemical reactions have provided new approaches to address this challenge. Three major strategies have been introduced in this emerging field: 1) one-pot in-situ activation of benzoic acids to generate intermediates such as benzoyl hypobromites or hypoiodites; 2) the use of specialized photocatalysts like biphenyl/1,4-dicyanobenzene to promote decarboxylation through photo-induced electron transfer or charge transfer processes; 3) photo-induced LMCT (Ligand-to-Metal Charge Transfer) strategy where copper or iron salts coordinate to the carboxylate anion and generate aromatic radicals upon visible light excitation. On the basis of these three strategies, this review will systematically summarize the development of visible-light-induced direct decarboxylative functionalization of aromatic carboxylic acids, focusing on the reaction mechanism and substrate scope, and discuss their prospects in organic synthesis.

芳基自由基是有机合成的重要中间体。通过廉价且容易获得的芳香族羧酸的直接脱羧生成这些反应性物质是一个有吸引力的目标。然而，这样的过程本质上表现出需要克服的高能量障碍，因此通常需要贵金属催化、化学计量氧化剂和恶劣的条件，并受到官能团耐受性差和原子经济性低等限制。近年来，光化学反应为应对这一挑战提供了新的方法。在这个新兴领域引入了三种主要策略：1） 苯甲酸的一锅原位活化以生成中间体，例如苯甲酰次溴酸盐或次碘酸盐;2） 使用专门的光催化剂，如联苯/1,4-二氰基苯，通过光诱导电子转移或电荷转移过程促进脱羧;3） 光诱导 LMCT（配体-金属电荷转移）策略，其中铜或铁盐与羧酸盐阴离子配位，并在可见光激发下产生芳香自由基。在这三种策略的基础上，本文将系统总结可见光诱导的芳香族羧酸直接脱羧官能团化的发展，重点介绍反应机理和底物范围，并讨论它们在有机合成中的前景。