A new method was developed to synthesize N²-allyl-substituted 1,2,3-triazoles via NIS mediated allylation of allenamides with mono- and unsubstituted NH-1,2,3-triazoles and benzotriazole. All the N²-allyl-substituted 1,2,3-triazoles have a relative stability. The ionic pair composed of a σ-complex and the conjugate base of the imide and the hydrogen bond between the conjugate base and NH-1,2,3-triazole were found to be generated, which selectively gave the desired N²-allylation products.