<scp>Metal‐Free</scp> Decarboxylation of α,<scp>β‐Unsaturated</scp> Carboxylic Acids for Carbon–Carbon and Carbon–Heteroatom Coupling Reactions
Xianjun Xu, Erik V. Van der Eycken, Huangdi Feng
Abstract
Metal‐free decarboxylative coupling reactions represent an alternative paradigm for carbon–carbon or carbon–heteroatom bond formation that complement more traditional metal catalysis approaches. In this review, recent advances in metal‐free decarboxylation reactions of α,β‐unsaturated carboxylic acids are highlighted. Two major reaction classes are covered: 1) generation of C–C, C–N, C–S, C–X bonds using propiolic acids; 2) transformations of alkenyl acids for C–C, C–P, C–N, C–S, C–X bond‐forming. Some cases involving electrochemistry and photochemistry represent a frontier area for carbon–carbon and carbon–heteroatom coupling processes. Additionally, the proposed mechanisms for both types of reactions are discussed.