The [3,3]-sigmatropic reaction led to allenyl azides 2a-h in an exergonic process, while the conversion of primary azide 1i toward 2i was through of an endergonic reaction. The allenyl azides have not been observed experimentally in the Banert cascade, however, these were isolated in other reactions, verifying their short stability at room temperature. For the proton abstraction of the prototropic pathway, the substituents showed an opposite and more pronounced effect than in the sigmatropic rearrangement (see Table ). The energy barrier for the abstraction of proton process of 1b (TS11-3b, 23.7 kcal/mol) was higher than that for the [3,3]-sigmatropic reaction (TS1-2b, 22.5 kcal/mol), which explains that the prototropic product 7b