From Figure , in the sigmatropic pathway, the propargylic azides 1x, undergo a [3,3]-sigmatropic rearrangement through TS1-2 leading to stable allenyl azides 2x. The mechanism of this reaction resembles that of the Winstein rearrangement, which proceeds via a cyclic transition structure from allylic azides. It was demonstrated that the [3,3]-sigmatropic rearrangement is the ratedetermining step of Banert cascade reaction. On the protrotopic pathway, a concerted and stepwise mechanism have been proposed depending on the base used. We envisioned that the prototropic reaction to lead allenyl azides from propargylic azides could take place in stepwise manner by analogy to the base-catalyzed alkyneallene isomerization via 1,3-proton transfer. The two-step mechanism involved abstraction of the propargylic proton by the oxygen methoxide via a TS11-3x leading to a carbanion intermediate,