Rahaman Ajijur, Chauhan Shivani Singh, Bhadra Sukalyan
Inorganic Materials and Catalysis Division, CSIR-Central Salt and Marine Chemicals Research Institute, G. B. Marg, Bhavnagar 364002, Gujarat, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
Org Biomol Chem. 2023 Jul 19;21(28):5691-5724. doi: 10.1039/d3ob00682d.
Chemists learn the most important transformations of the carboxylic acid functionality (COOH) from as early as the first semester of their studies. Carboxylic acids are not only safe to store and handle, but also broadly accessible with great structural diversity either from commercial sources or by means of a large variety of well-known synthesis routes. Consequently, carboxylic acids have long been recognized as a highly adaptable starting material in organic synthesis. A large body of reactions of carboxylic acids are based on catalytic decarboxylative conversions, in which the COOH group of carboxylic acids is catalytically replaced without trace by extrusion of CO chemo- and regioselectively. Within the last two decades, the area of catalytic decarboxylative transformations has expanded significantly by utilizing various classes of carboxylic acids as the substrate, including (hetero)aromatic acids, alkyl acids, α-keto acids, α,β-unsaturated acids and alkynoic acids. A literature survey reveals that compared to aromatic acids, the number of original research papers on decarboxylative reactions of α-keto acids, α,β-unsaturated acids and alkynoic acids has been rising every year lately, particularly within past five to six years. The prime aim of the current review is to give an overview of the decarboxylative transformations of α-keto acids, α,β-unsaturated acids and alkynoic acids that have been developed since 2017. The article focuses on the decarboxylative functionalizations that occur in the presence or absence of transition metal catalysts and/or under photoredox catalysis.
早在大学学习的第一学期，化学家们就开始学习羧酸官能团（COOH）最重要的转化反应。羧酸不仅储存和处理安全，而且无论是从商业来源还是通过各种知名的合成路线，都能广泛获取且结构多样。因此，长期以来，羧酸在有机合成中一直被视为一种高度适应性强的起始原料。大量的羧酸反应基于催化脱羧转化，其中羧酸的COOH基团通过化学和区域选择性地挤出CO而被催化无痕取代。在过去的二十年里，通过使用各类羧酸作为底物，催化脱羧转化领域显著扩展，这些羧酸包括（杂）芳族酸、烷基酸、α-酮酸、α,β-不饱和酸和炔酸。文献调查显示，与芳族酸相比，近年来关于α-酮酸、α,β-不饱和酸和炔酸脱羧反应的原创研究论文数量逐年增加，尤其是在过去的五到六年里。本综述的主要目的是概述自2017年以来开发的α-酮酸、α,β-不饱和酸和炔酸的脱羧转化反应。本文重点关注在过渡金属催化剂存在或不存在以及/或者在光氧化还原催化下发生的脱羧官能团化反应。
