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对于催化 [2+2] 循环添加和乙烯化:金属循环的几何决定了选择性

Coralie Duchemin¹, Junho Kim¹, Paul J Chirik¹

¹Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.

|July 28, 2023

概括

铁催化剂含有特定的皮里丁 (((二胺)) 连接体,可选择性地催化布达和乙烯的 [2+2] 循环添加. 改变连接物结构改变了选择性,产生了乙烯基环丁或六二烯产物.

科学领域:

有机金属化学有机金属化学
催化剂是一种催化剂.
有机合成有机合成

背景情况:

二胺 (PDI) 铁复合物是烯转化过程中的有效催化剂.
在 [2+2] - 循环添加反应中控制化学选择性仍然是催化的一个重大挑战.

研究的目的:

为了研究连接体对称性对铁催化 [2+2] 循环添加丁和乙烯的化学选择性的影响.
阐明导致不同产品分布的机制性途径.

主要方法:

合成和表征C_S-对称 (基) 替代PDI铁甲基前催化剂.
在布他和乙烯的 [2+2] 循环添加中对前催化剂的评估.
机理学研究包括前催化剂稳定性,静止状态识别和同位素标记 (H,C).

主要成果:

在C_S-对称的催化剂中,可制造出乙烯基旋和 (Z) - 六合-1,4-二烯的混合物.
在C_2v-对称的,化PDI铁催化剂中,仅通过可逆的 [2+2]-循环添加产生了乙烯基循环butan.
两个二磁性金属循环被确定为催化剂静止状态.
六二烯的形成涉及可逆的氧化循环,而环丁的形成则通过跨金属循环的不可逆的还原性消除进行.

结论:

配体设计,特别是PDI骨干上的基与基替代,决定了铁催化 [2+2]-环添加的化学选择性.
机械洞察力揭示了乙烯和六二烯形成的不同途径.
双利化) PDI铁催化剂为 [2+2] 循环添加提供了独特的选择性,进步了铁催化领域.

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