Theoretical kinetic and thermodynamic studies of the strain energies and ring size effects of the 1,3-dipolar cycloaddition reactions on ethinamate medicine analogs

In this study, strain effects of a side ring on the 1,3-dipolar cycloaddition reactions were investigated. It was important to find a reactant with a ring closed at the structure of the selected dipolarophile. To this aim, the ring-closed structure, ethinamate (E1), medicine for insomnia, and its analogous compounds (E2-E4) selected as dipolarophile for 1,3-DC reaction with azide derivatives (a, b and c) as 1,3-dipoles to achieve the 1,2,3-triazole products. For each set of reactions was employed DFT method to determine the critical structures (reactants, transition states and products) energy pathways and results analyzed and discussed from kinetic and thermodynamic point of view. The DFT-B3LYP/6-31G* method was accepted to calculate energy levels of the RTP (Reactants, Transition states (TS), Products) of the reactions, the free energies of reaction (ΔrG and ΔG#; in kcal mol−1), rate constants by using Eyring’s equation (k and k′), and structural data were obtained and discussed. The side ring size and strain effects have been investigated in the 1,3-DC reactions to produce the 1,2,3-triazole derivatives from ethinamate and its analogs.Graphical abstract
Source: Journal of Molecular Structure - Category: Molecular Biology Source Type: research