Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States.
J Am Chem Soc. 2020 Mar 11;142(10):4598-4603. doi: 10.1021/jacs.0c00356. Epub 2020 Feb 27.
Polysubstituted cyclohexenes bearing 1,3 () substitution patterns are challenging to access using the Diels-Alder reaction (the - rule). Here, we report a cobalt-catalyzed reductive [5 + 1]-cycloaddition between a vinylcyclopropane and a vinylidene to provide methylenecyclohexenes bearing all- relationships. Vinylidene equivalents are generated from 1,1-dichloroalkenes using Zn as a stoichiometric reductant. Experimental observations are consistent with a mechanism involving a cobaltacyclobutane formed from a [2 + 2]-cycloaddition between a cobalt vinylidene and a vinylcyclopropane.
带有 1,3()取代模式的多取代环己烯很难通过 Diels-Alder 反应(-规则)获得。在这里,我们报告了一种钴催化的还原 [5+1]-环加成反应,在该反应中,乙烯基环丙烷与亚乙烯基之间发生反应,生成具有全顺式关系的亚甲基环己烯。亚乙烯基等价物是使用 Zn 作为化学计量还原剂从 1,1-二氯代烯烃中生成的。实验观察结果与一个反应机理一致,该机理涉及钴亚乙烯基和乙烯基环丙烷之间的[2+2]-环加成反应生成的钴环丁烷。