NMR and DFT Studies of 2-Oxo-1,2,3,4-tetrahydropyridines: Solvent and Temperature Effects

作者：Memarian Hamid R^*; Kalantari Mahdieh; Sabzyan Hassan^*

来源：Australian Journal of Chemistry, 2018, 71(5): 380-388.

DOI：10.1071/CH18018

Various 5-carboethoxy-2-oxo-1,2,3,4-tetrahydropyridines and their corresponding oxidation products containing methoxy or nitro groups on different positions of the C-4-aryl ring were synthesized and the effect of steric and electrostatic interactions of these aryl substituents on the characteristic peaks in H-1 NMR spectra were investigated. In addition, the intermolecular interaction of the parent compound and its oxidized form with solvent was experimentally investigated. For this, H-1 NMR spectra of these compounds at different concentrations and temperatures in [D6]DMSO and CDCl3 were investigated. For comparison of the dimerization ability of these heterocyclic compounds with different conformations, the binding electronic energies, the total enthalpies and free energies of dimerization in the gas and solution phases, and the QTAIM (quantum theory of atoms-in-molecules) analysis were determined. These interactions were also studied using density functional theory at the B3LYP/6-311++G(d,p) level. The theoretical results are in good agreement with the experimental results and indicate that the electronic effect of the methoxy and nitro groups on the C-4-aryl ring influences the electron density of the heterocyclic ring via the sigma bond and, consequently, the chemical shift of the heterocyclic ring protons.

• 出版日期2018