Reaction mechanism studies made simple using simulated annealing. Potential energy surface exploration

International audienceA new and easy way to study reaction mechanisms by theoretical means is proposed. Simulated annealing is used to explore the potential energy surface of three different systems. This approach enables a facile finding of most stationary points involved in the various possible reaction paths arising from a given molecular system and thus allows one to determine a whole set of competing reactions. Therefore, by a comparison of the activation barriers, we can qualitatively estimate whether a reaction should be stereoselective or if side-products may arise. This paper deals with the [2 + 2] cycloaddition leading to beta-lactones and the thermolysis of thiirane and thiiranium cation