Do we fully understand what controls chemical selectivity?

Reaction rates and product selectivity of kinetically controlled reactions are not always sufficiently described by standard RRKM or TST theory. Reactions taking place on potential energy surfaces featuring a valley ridge inflection point belong to this class of reactions. Though various research groups could show that reaction path bifurcations are far from being an exception in organic reactions the underlying principles that govern product distributions of those bifurcating reaction pathways are yet not fully understood. This Perspective has the intention to provide an overview of how far our understanding and the development of the theoretical foundation have progressed.