Expedient Synthesis of Thermally Stable Acyclic Amino(haloaryl)carbenes: Experimental and Theoretical Evidence of “Push–Pull” Stabilized Carbenes,Journal of the American Chemical Society

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Expedient Synthesis of Thermally Stable Acyclic Amino(haloaryl)carbenes: Experimental and Theoretical Evidence of “Push–Pull” Stabilized Carbenes
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2024-06-10 , DOI: 10.1021/jacs.4c04872
Damien Magis ₁ , Jorge Juan Cabrera-Trujillo ₂ , Joan Vignolle ₃ , Jean-Marc Sotiropoulos ₂ , Daniel Taton ₃ , Karinne Miqueu ₂ , Yannick Landais ₁

Affiliation

A library of novel structurally related singlet carbenes, namely, acyclic amino(haloaryl)carbenes, was designed by a high-yielding two-step procedure, and their chemical stability explored both experimentally and theoretically. Thanks to a careful selection of both the amino and the aryl substitution pattern, these carbenes exhibit a wide range of stability and reactivity, spanning from rapid self-dimerization for carbenes featuring ortho-F substituents to very high chemical stability as bare carbenes, up to 60 °C for several hours for compounds carrying ortho-Br substituents. Their structure was determined through NMR and X-ray diffraction studies, and their reactivity evaluated in benchmark reactions, highlighting the ambiphilic character of this novel class of singlet carbenes. In contrast with previously reported aryl substituents incorporating o-CF₃ and t-Bu groups, which were considered “spectator”, the high chemical stability of some of these carbenes relates to the stabilization of the σ-orbital of the carbene center by the π-accepting haloaryl substituent through delocalization. Kinetic protection of the carbene center is also provided by the ortho-halogen atoms, as demonstrated computationally. This push–pull stabilization effect makes acyclic amino(haloaryl) carbenes among the most ambiphilic stable carbenes reported to date, holding promise for a variety of applications.

中文翻译：

热稳定无环氨基（卤芳基）卡宾的便捷合成：“推拉”稳定卡宾的实验和理论证据

通过高产两步程序设计了一个新型结构相关的单线态卡宾库，即无环氨基（卤代芳基）卡宾，并从实验和理论上探索了它们的化学稳定性。由于仔细选择了氨基和芳基取代模式，这些卡宾表现出广泛的稳定性和反应性，从具有邻位-F取代基的卡宾的快速自二聚到作为裸卡宾的非常高的化学稳定性，高达对于带有邻位-Br 取代基的化合物，60 °C 几个小时。它们的结构是通过核磁共振和 X 射线衍射研究确定的，并在基准反应中评估了它们的反应性，突出了这类新型单线态卡宾的两亲性特征。与之前报道的包含o -CF ₃和t -Bu 基团的芳基取代基（被认为是“旁观者”）相比，其中一些卡宾的高化学稳定性与 π 对卡宾中心 σ 轨道的稳定有关。 -通过离域接受卤代芳基取代基。正如计算所证明的那样，邻位卤素原子也提供了卡宾中心的动力学保护。这种推拉稳定效应使无环氨基（卤代芳基）卡宾成为迄今为止报道的两亲性最稳定的卡宾之一，有望在各种应用中发挥作用。

更新日期：2024-06-10

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