德国马克斯普朗克研究所Tobias Ritter团队报道了通过苯甲酸的自由基脱羧碳金属化策略解决芳香族脱羧氟化反应。相关研究成果发表在2021年4月5日出版的《美国化学会杂志》。

丰富的芳香羧酸在自然界和合成过程中具有巨大的结构多样性。到目前为止，苯甲酸的脱羧功能化主要是通过过渡金属催化的脱羧交叉偶联来实现的。然而，通常需要140℃反应温度的热脱羧碳金属化的高活化势垒限制了底物范围以及能够维持这种条件的合适反应的范围。许多反应，如用于脂肪族羧酸的脱羧基氟化反应，在目前的反应化学中是芳香类反应所无法达到的。

该文中，研究人员报告了一种概念上不同的方法，通过低势垒光诱导配体到金属电荷转移（LMCT）的自由基脱羧碳金属化策略，产生一种假定的高价芳基铜（III）络合物，从中可以发生多功能的简易还原消除。

附：英文原文

Title: Radical Decarboxylative Carbometalation of Benzoic Acids: A Solution to Aromatic Decarboxylative Fluorination

Author: Peng Xu, Priscila López-Rojas, Tobias Ritter

Issue&Volume: April 5, 2021

Abstract: Abundant aromatic carboxylic acids exist in great structural diversity from nature and synthesis. To date, the synthetically valuable decarboxylative functionalization of benzoic acids is realized mainly by transition-metal-catalyzed decarboxylative cross couplings. However, the high activation barrier for thermal decarboxylative carbometalation that often requires 140 °C reaction temperature limits both the substrate scope as well as the scope of suitable reactions that can sustain such conditions. Numerous reactions, for example, decarboxylative fluorination that is well developed for aliphatic carboxylic acids, are out of reach for the aromatic counterparts with current reaction chemistry. Here, we report a conceptually different approach through a low-barrier photoinduced ligand to metal charge transfer (LMCT)-enabled radical decarboxylative carbometalation strategy, which generates a putative high-valent arylcopper(III) complex, from which versatile facile reductive eliminations can occur. We demonstrate the suitability of our new approach to address previously unrealized general decarboxylative fluorination of benzoic acids.

DOI: 10.1021/jacs.1c02490

Source: https://pubs.acs.org/doi/10.1021/jacs.1c02490