Reversible, Room-Temperature CC Bond Activation of Benzene by an Isolable Metal Complex

The
activation of CC bonds is of fundamental interest in
the construction of complex molecules from petrochemical feedstocks.
In the case of the archetypal aromatic hydrocarbon benzene, CC
cleavage is thermodynamically disfavored, and is brought about only
by transient highly reactive species generated in situ. Here we show that the oxidative addition of the CC bond
in benzene by an isolated metal complex is not only possible, but
occurs at room temperature and reversibly at a single aluminium center
in [(NON)­Al]− (where NON = 4,5-bis­(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene). Selectivity over CH
bond activation is achieved kinetically and allows for the generation
of functionalized acyclic products from benzene.

C-C键的激活在由石油化工原料构建复杂分子方面具有根本性的研究意义。以典型的芳香烃苯为例，C-C键的断裂在热力学上是不利的，其断裂过程仅由现场生成的瞬态高活性物种引发。本研究揭示了通过单个金属配合物对苯中的C-C键进行氧化加成反应不仅是可行的，而且在室温下即可进行，且在[(NON)−Al]−（其中NON代表4,5-双(2,6-二异丙基安尼利多)-2,7-二叔丁基-9,9-二甲基黄烷）的单一铝中心实现可逆性。通过动力学控制实现对C-C键激活的选择性，从而允许从苯生成功能化的非环状产物。