The conformer-related reaction pathways in the cycloaddition of vinylaziridines with alkynes were calculated using DFT methods. The calculated results reveal that the ring-opening products of vinylaziridines possess two different conformers with the specific sites available for coordination of alkynes. The formed alkyne-coordinated complexes results in the different C-N bond addition intermediates. In the cycloaddition reaction catalyzed by [Rh(eta(6) -C10H8)(COD)]SbF6, the intermediate needs an isomerization to yield the final [5 + 2] cycloaddition product. In the reaction catalyzed by [Rh(NBD)(2)]BF4, such an isomerization is dispensable to yield the final [3 + 2] cycloaddition product.