The mechanism proposed for both pathways of Banert cascade is depicted in Figure . Topczewski and co-workers have reported that the propargylic azides 1a-h undergo the sigmatropic pathway when these are warmed at 60 °C over 24 h, generating the corresponding 1,2,3-triazoles (6a-h). To evaluate the prototropic pathway the azides were heated at 60 °C by 24 h using NaOMe as base in MeOH. Under these conditions, for azides 1a-c only the sigmatropic products were obtained, while the azide 1h, substituted with CN, exclusively led to the prototropic product (7h) in high yield. For azides 1d-g, the products of both pathways were obtained in different ratios. In order to study the reaction mechanisms and to compare the calculations with the experimental results, we have chosen the propargylic azides 1a-h as starting materials. Such reactants are secondary azides and we also studied the mechanism of the primary azide 1i, which has shown to follow-up the sigmatropic path when the reaction was promoted by silver salts. In the Tables and are listed the relative free energies for sigmatropic and prototropic systems. a Relative free energies were computed from the corresponding reactive complexes and b from the corresponding propargylic azide 1x. c See Figure , for identification of the structures.