Methylenespiro[2.3]hexanes via Nickel-Catalyzed Cyclopropanations with [1.1.1]Propellane.
Methylenespiro[2.3]hexanes via Nickel-Catalyzed Cyclopropanations with [1.1.1]Propellane.
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DOI：
10.1021/jacs.9b10689
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发表时间：
2019-11
影响因子：
15
通讯作者：
Songjie Yu;Adam Noble;R. Bedford;V. Aggarwal
中科院分区：
文献类型：
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作者：
Songjie Yu;Adam Noble;R. Bedford;V. Aggarwal
[1.1.1]螺桨烷是一种高度紧张的三环烃，其反应性主要是通过中心反键的加成反应提供双环[1.1.1]戊烷衍生物。这些反应在自由基和双电子途径下进行，因此提供了获得各种产物的途径。相反，[1.1.1]螺桨烷的过渡金属催化反应是不发达的，缺乏合成效用，与报道的例子通常产生开环结构异构体，二聚体和三聚体的混合物，往往具有差的选择性。本文中，我们报道了镍（0）催化剂使得能够使用[1.1.1]螺桨烷作为一系列官能化烯烃的环丙烷化中的卡宾前体，得到亚甲基螺[2.3]己烷产物。计算研究为Ni（0）-[1.1.1]螺桨烷配合物的初始形成提供了支持，随后协同的双C-C键活化得到关键的3-亚甲基环亚丁基-镍中间体。
[1.1.1]Propellane is a highly strained tricyclic hydrocarbon whose reactivity is dominated by addition reactions across the central inverted bond to provide bicyclo[1.1.1]pentane derivatives. These reactions proceed under both radical and two-electron pathways, hence providing access to a diverse array of products. Conversely, transition metal-catalyzed reactions of [1.1.1]propellane are underdeveloped and lack synthetic utility, with reported examples generally yielding mixtures of ring-opened structural isomers, dimers, and trimers, often with poor selectivity. Herein, we report that nickel(0) catalysis enables the use of [1.1.1]propellane as a carbene precursor in cyclopropanations of a range of functionalized alkenes to give methylenespiro[2.3]hexane products. Computational studies provide support for initial formation of a Ni(0)-[1.1.1]propellane complex followed by concerted double C-C bond activation to give the key 3-methylenecyclobutylidene-nickel intermediate.