atom moves into the plane of the aromatic ring, forming a palladacycle intermediate and carboxylic acid. The palladacycle intermediate can undergo further (coupling) reactions and form a variety of products via reductive elimination. In previous studies, the rate and regioselectivity controlling step was identified as the formation of the palladacycle. The regioselectivity could be correctly predicted by calculation and comparison of the activation barrier of this step by Davies et al. . Hence, the reaction site for which the activation barrier is the lowest is predicted to be the most probable one. Tomberg et al. established that the regioselectivity could be predicted by calculation and comparison of the relative energies of the proceeding palladacycle intermediate, as postulated in the Bell-Evans-Polanyi principle. Focussing on the intermediates allows for easier automation of the calculations since a minimum instead of a saddle point structure on the potential energy surface is located which can be done straightforwardly using standard optimization algorithms.