Factors Controlling the Aluminum(I)-meta-Selective C-H Activation in Arenes.

The so far poorly understood factors controlling the complete meta-selectivity observed in the C-H activation reactions of alkylarenes promoted by aluminyl anions have been explored in detail by means of Density Functional Theory calculations. To this end, a combination of state-of-the-art computational methods, namely the activation strain model of reactivity and energy decomposition analysis, has been applied to quantitatively unveil the origin of the selectivity of the transformation as well as the influence of the associated potassium cation. It is found that the selectivity takes place during the initial nucleophilic addition step where the key LP(Al)→π*(C=C) molecular orbital interaction is more stabilizing for the meta-pathway, which results in a stronger interaction between the reactants along the entire transformation.