众所周知,路易斯碱能稳定缺电子物种。
该文中,研究人员证明路易斯碱可以提高单配位亚铝酸盐1的氧化还原性能,该亚铝酸盐1仅具有铝壳层的四个价电子。1与N-杂环卡宾(NHC)的配位有效地缩小了HOMOLUMO间隙,从而增强了随后的无环单NHC稳定的亚铝质2的反应性,该亚铝质2与单线态卡宾是等电子的。此外,该碱配位完全逆转了亚铝酸盐的主要化学反应性(即亲电性/亲核性)。与1形成显著对比的是,2在室温下容易与萘和联苯发生[4+1]环加成反应。
引人注目的是,Al在2中增强的双亲性也使惰性芳烃的芳香CC键能够以分子内和分子间的方式轻易断裂,得到3和5。5的形成代表了联苯中芳香族C(3)C(4)键被单原子中心裂解的第一个例子。
附:英文原文
Title: Modulating the Frontier Orbitals of an Aluminylene for Facile Dearomatization of Inert Arenes
Author: Xin Zhang, Liu Leo Liu
Issue&Volume: 2022-01-10
Abstract: Lewis bases are well known to stabilize electron-deficient species. We demonstrate herein that the redox property of a monocoordinated aluminylene 1 featuring only four valence electrons for the shell of Al can be boosted by a Lewis base. The coordination of 1 with an N-heterocyclic carbene (NHC) effectively shrinks the HOMOLUMO gap, thereby enhancing the reactivity of the ensuing acyclic mono-NHC-stabilized aluminylene 2 , which is isoelectronic with singlet carbenes. Moreover, such base coordination completely reverses the predominant chemical reactivity (i.e. electrophilicity/nucleophilicity) of aluminylenes. In marked contrast to 1 , 2 readily undergoes a [4+1] cycloaddition reaction with naphthalene and biphenylene at room temperature. Strikingly, the enhanced ambiphilic nature of Al in 2 also enables facile cleavage of aromatic CC bonds of inert arenes in both intra- and intermolecular fashion affording 3 and 5 . The formation of 5 represents the first example of the cleavage of aromatic C(3)C(4) bond in biphenylene by a single atom center.
DOI: 10.1002/anie.202116658
Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202116658
Angewandte Chemie:《德国应用化学》,创刊于1887年。隶属于德国化学会,最新IF:12.959
官方网址:https://onlinelibrary.wiley.com/journal/15213773
投稿链接:https://www.editorialmanager.com/anie/default.aspx