Ligand and solvent effects on cobalt(I)-catalysed reactions: Alkyne dimerisation versus [2+2+2]-cyclotrimerisation versus Diels–Alder reaction versus [4+2+2]-cycloaddition
作者:Gerhard Hilt、Wilfried Hess、Thomas Vogler、Christoph Hengst
DOI:10.1016/j.jorganchem.2005.03.067
日期:2005.11
bromide complex, zinc and zinc iodide in acetonitrile. With 2–5 mol% of the cobalt catalyst at ambient temperatures 1,2,4-triphenylbenzene could be obtained in 99% yield and in excellent regioselectivity (95:5) in 10 min reaction time. Competition experiments of phenylacetylene and isoprene were performed. A preference for the cyclotrimerisation reaction was found for the diimine cobalt complex in acetonitrile
当CoBr 2时,钴催化的苯基乙炔转化导致线性烯炔二聚产物在不存在路易斯酸的情况下,用镁将(dppe)活化。相反,在路易斯酸的存在下,环三聚反应过程是有利的。在几种测试的配体体系和溶剂中,使用由二亚胺溴化钴配合物,乙腈中的锌和碘化锌组成的催化剂体系可获得最佳结果。在室温下使用2–5 mol%的钴催化剂,可以在10分钟的反应时间内以99%的收率和出色的区域选择性(95:5)获得1,2,4-三苯苯。进行了苯乙炔和异戊二烯的竞争实验。对于乙腈中的二亚胺钴配合物,发现优先进行环三聚反应,而二氯甲烷中的钴(dppe)配合物则有利于Diels-Alder反应。