Metallaphotoredox-catalyzed alkynylcarboxylation of alkenes with CO2 and alkynes for expedient access to β-alkynyl acids

Carboxylation with CO2 offers an attractive and sustainable access to valuable carboxylic acids. Among these methods, direct C−H carboxylation of terminal alkynes with CO2 has attracted much attention for one-carbon homologation of alkynes, enabling rapid synthesis of propiolic acids. In contrast, the multi-carbons homologation of alkynes with CO2 to construct important non-conjugated alkynyl-containing acids has not been reported. Herein, we present the first alkynylcarboxylation of alkenes with CO2 via photoredox and copper dual catalysis. This protocol provides a direct and practical method to form valuable non-conjugated alkynyl acids from readily available alkynes, alkenes and CO2. Additionally, this approach also features mild (room temperature, 1 atm of CO2) and redox-neutral conditions, high atom and step economy, good functional group tolerance, and high selectivities. Moreover, diverse transformations of the β-alkynyl acid products and the rapid synthesis of bioactive molecule (GPR40/FFA1 agonist) further illustrate the synthetic utility of this methodology.

以二氧化碳（CO₂）为原料的羧化反应，是获取高价值羧酸的兼具吸引力与可持续性的途径。在这类反应中，以二氧化碳参与的端炔直接C-H羧化反应，因可实现炔烃的一碳同系化、快速合成丙炔酸类化合物，而受到广泛关注。与之相对，通过二氧化碳与炔烃的多碳同系化来构建重要的非共轭含炔基羧酸的策略，迄今尚未见报道。本文首次报道了基于光氧化还原与铜双催化体系，以二氧化碳实现烯烃的炔基羧化反应。该策略可从易得的炔烃、烯烃与二氧化碳出发，直接且实用地合成高价值的非共轭含炔基羧酸。此外，该方法具备反应条件温和（室温、二氧化碳分压1 atm）、氧化还原中性、原子经济性与步骤经济性高、官能团兼容性良好且选择性优异的特点。不仅如此，β-炔基羧酸产物可进行多样转化，且可快速合成生物活性分子（GPR40/FFA1激动剂），进一步彰显了该方法的合成应用价值。