2,5‐Bis(2‐(diphenylphosphino)phenyl)‐1,3,4‐oxadiazole ligands and their Cu(I) complexes for Sonogashira coupling reaction |
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Authors: | Cai‐Xia Lin Jia‐Fang Zhu Qing‐Shan Li Li‐Hua Ao Yan‐Juan Jin Feng‐Bo Xu Fang‐Zhong Hu Yao‐Feng Yuan |
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Affiliation: | 1. State Key Laboratory and Institute of Elemento‐Organic Chemistry, Nankai University, Tianjin, People's Republic of China;2. Department of Chemistry, Fuzhou University, Fuzhou, People's Republic of China |
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Abstract: | Two diphosphane ligands – 2,5‐bis(2‐(diphenylphosphino)‐5‐R)phenyl)‐1,3,4‐oxadiazole ( L1 , R = H, L2 , R = OMe) and their binuclear complexes, L1Cu and L2Cu , were prepared and characterized. The molecular structures of L1Cu and L2Cu , as perchlorate salts, were established by X‐ray crystallography, which showed them to be binuclear complexes with each Cu atom tetrahedrally coordinated by two P atoms and two N atoms. The ligands and their Cu(I) complexes catalyzed Sonogashira coupling reactions of iodobenzene with phenylacetylene in the presence of K2CO3 under Pd‐free conditions. Coupling reactions catalyzed by L1 or L2 with Cu(MeCN)4ClO4 in situ exhibited better yields than those by the corresponding Cu(I) complexes L1Cu or L2Cu . Detailed studies showed L1 or L2 with Cu(MeCN)4ClO4 to be suitable catalysts for the coupling reaction of terminal alkynes and aryl halides. The coupling reactions of aryl iodides with electron‐withdrawing groups showed better results. Copyright © 2014 John Wiley & Sons, Ltd. |
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Keywords: | Sonogashira coupling diphosphane ligands Cu(I) complexes Pd‐free conditions |
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