Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds Research and Application, School of Chemistry and Environmental Science, Xiangnan University, Chenzhou 423000, China.
Molecules. 2023 Jun 29;28(13):5083. doi: 10.3390/molecules28135083.
Conjugated diyne derivatives are important scaffolds in modern organic synthetic chemistry. Using the Glaser reaction involves the coupling of terminal alkynes which can efficiently produce conjugated diyne derivatives, while the use of a stoichiometric amount of copper salts, strong inorganic base, and excess oxidants is generally needed. Developing an environmentally friendly and effective method for the construction of symmetrical 1,3-diynes compounds by Glaser coupling is still highly desirable. In this study, we present an economical method for the production of symmetric diynes starting from various terminal acetylenes in a Glaser reaction. A simple and practical bis-N-heterocyclic carbene ligand has been introduced as efficient ligands for the Cu-catalyzed Glaser reaction. High product yields were obtained at 100 °C for a variety of substrates including aliphatic and aromatic terminal alkynes and differently substituted terminal alkynes including the highly sterically hindered substrate 2-methoxy ethynylbenzene or 2-trifluoromethyl ethynylbenzene and a series of functional groups, such as trifluoromethyl group, ester group, carboxyl group, and nitrile group. The established protocol is carried out in air under base-free condition and is operationally simple. These research work suggest that bis-N-heterocyclic carbene could also an appealing ligand for Glaser reaction and provide a reference for the preparation of symmetric 1,3-diynes in industrial filed.
共轭二炔衍生物是现代有机合成化学中的重要支架。使用 Glaser 反应涉及末端炔烃的偶联，这可以有效地产生共轭二炔衍生物，而通常需要使用化学计量的铜盐、强无机碱和过量的氧化剂。开发一种环境友好且有效的方法来通过 Glaser 偶联构建对称 1,3-二炔化合物仍然是非常需要的。在这项研究中，我们提出了一种从各种末端炔烃在 Glaser 反应中制备对称二炔的经济方法。我们引入了一种简单实用的双氮杂环卡宾配体作为 Cu 催化的 Glaser 反应的有效配体。在 100°C 下，各种底物包括脂肪族和芳香族末端炔烃以及不同取代的末端炔烃，包括高度空间位阻的底物 2-甲氧基乙炔基苯或 2-三氟甲基乙炔基苯和一系列官能团，如三氟甲基、酯基、羧基和腈基，都能获得很高的产物收率。所建立的方案在无碱条件下在空气中进行，操作简单。这些研究工作表明，双氮杂环卡宾也可以作为 Glaser 反应的一种有吸引力的配体，并为工业领域中对称 1,3-二炔的制备提供参考。
