Styrene derivatives containing electron-withdrawing substituents reacted much more quickly than those with electron-donating groups. For example, upon addition of 1 equiv. of 4-(trifluoromethyl)styrene 4c was formed nearly quantitatively within 3 h. In the case of 4a and 4b an excess of the respective styrenes (10 equiv.) was necessary to obtain reasonable reaction rates and full conversion of 1 at room temperature. The formation of the products in these cases was found to follow first order kinetics, with t½ ≈ 24 h (4a) and t½ ≈ 71 h (4b), respectively. The highest reaction rates at room temperature were observed in the reaction of 1 with 2vinylpyridine which affords 4d almost instantly when carried out in the presence of catalytic amounts (1-2 mol %) of MgBr2. MgBr2 appears to act as a Lewis acid catalyst preventing coordination of the pyridine nitrogen to Al and activating the substrate for the C-H activation reaction (vide infra).