It was proposed that allenyl azides get cyclized rapidly through an electrocyclization reaction to form triazafulvene intermediate. Owning to the highly electrophilic character of triazafulvene, it can be easily trapped by various nucleophiles, generating 1,2,3-triazole. Afterwards, Banert revealed that when the reaction is catalyzed by a base, the cascade could take place via a prototropic pathway (Scheme 2b), generating a regioisomeric 1H-1,2,3-triazole as product from the same starting material.