Before revision:  To this goal we introduce an extension of the Dominant Reaction Pathways (DRP) formalism, in which the quantum corrections to the classical  Langevin dynamics are rigorously taken into account to order hbar^2 . We apply our method to study the C 7_eq -> C 7_ax transition of alanine dipeptide.
After revision:  To this goal we introduce an extension of the Dominant Reaction Pathways (DRP) formalism, in which the quantum corrections to the classical Langevin dynamics are rigorously taken into account to second order in h-bar. We first illustrate our approach with a simple toy model and then we apply it to study the C 7_eq -> C 7_ax transition of alanine dipeptide.