Stereochemistry and spectroscopic analysis of bis-Betti base derivatives of 2,3-dihydroxynaphthalene

Density functional theory (DFT) was used to study the stereochemistry, thermodynamic stability, and spectra of recently synthesized bis-Betti base derivatives of 2,3-dihydroxynaphthalene obtained through multicomponent reactions of 2,3-dihydroxynaphthalene with aminoisoxazole and benzaldehyde derivatives. The stereochemistry of the products was investigated by theoretically calculating the infrared (IR) and proton nuclear magnetic resonance ((1)H NMR) spectra of the diastereomers and comparing them to the corresponding experimental data. The thermochemical properties of the reactions, including the enthalpy, internal energy, entropy, and Gibbs free energy, were also calculated. The diastereoselectivity of the reactions was estimated from the equilibrium distribution of diastereomers. According to the results, the synthesis of bis-Betti bases is exothermic and accompanied by a decrease in entropy. The energy difference between the diastereomers is quite small, but the Gibbs free energy change for the equilibrium syn <−> anti favors the anti over syn configuration. These results are in good agreement with experimental observations.