The NBO analysis was performed to identify the intramolecular interactions between the electron density of the reactants and their effect on the charge distribution. The hyperconjugative interactions in which *CC and CC of the allylic group act as acceptor and donor orbitals, respectively, were examined according to the second-order perturbation energy (E ) in the NBO analysis. In the reactants, there were hyperconjugative interactions among C 1 -N 1 , C 1 -C Me /H 1b and C 1 -H 1a donor orbitals and *C 2 C 3 antibonding orbital as the acceptor. A weak hyperconjugative interaction was also found between N 1 →*C 2 C 3 . The C 2 C 3 acted as donor orbital in the interactions with *C 1 -C Me /H 1b , *C 1 -H a , *C 1 -N 1 and *C 4 -C 5/6 (See the Supporting Information). The E associated with the most relevant hyperconjugative interactions in the 1a-i are summarized in Table . The strong stabilization of electron density was associated with the conjugative interactions C 4 C 5/6 →*C 2 C 3 and C 2 C 3 → C 4 C 5/6 . The E values for these interactions were higher in reactants 1a and 1c, particularly for the former, than in 1b. These reactants did not follow the prototropic reaction. The E for C 4 C 5/6 →*C 2 C 3 in 1d was lower than in 1b, while both reactants showed similar values of E for the C 2 C 3 →C 4 C 5/6 interactions.