resulted in an unusual C–C coupling reaction which is suggested to result from a sterically induced reductive process. An assessment of the Mg, Ca, and Sr alkyl compounds as precatalysts for the intramolecular hydroamination of aminoalkenes evidenced enhanced reactivity, which is ascribed to the greater solution stability of the catalytically active species. Most notably the calcium species may even be applied
位阻双(亚
氨基)ac烯(dipp-BIAN)与烷基
钾或较重的碱土二烷基[Ae CH(SiMe 3)2 } 2(THF)2 ]的反应(Ae = Mg,Ca,Sr )试剂会导致芳族
配体脱芳香化。杂配碱土
金属烷基化物对Schlenk型重新分布具有增强的稳定性,但是当双(三甲基甲
硅烷基)甲基取代基被较低整体空间需求的阴离子
配体取代时,会发生溶液交换。相反,用[Ba CH(SiMe 3)2 } 2(THF)2进行的类似反应]证明溶液易于重新分布,并导致异常的C–C偶联反应,这提示是由空间诱导的还原过程引起的。评估Mg,Ca和Sr烷基化合物作为
氨基烯烃分子内加
氢胺化的前催化剂,证明了反应活性的提高,这归因于催化活性物质的更大的溶液稳定性。最值得注意的是,该
钙物质甚至可以用于在两个烯基位置上带有烷基取代基的底物的高产环化。