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键的活化在由石油化工原料构建复杂分子的过程中具有根本意义。在典型芳烃苯的案例中，C-C键的断裂在热力学上是不利的，并且仅由现场生成的短暂且高度活泼的物种引起。本研究揭示了通过一个孤立金属复合物在苯中C-C键的氧化加成不仅可行，而且可在室温下进行，并在[(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）的单个铝中心实现可逆反应。在动力学上对C-C键活化的选择性，使得从苯生成功能化的非环状产物成为可能。