Synthesis, Crystal Structure and DFT Studies of 1,3-Dimethyl-5-propionylpyrimidine-2,4,6(1H,3H,5H)-trione

Abstract

Novel 1,3-Dimethyl-5-propionylpyrimidine-2,4,6(1H,3H,5H)-trione was synthesized and recrystallized from ethanol. The compound was characterized by 1 H NMR, 13 C NMR in CDCl 3 , DMSO-d 6 and acetone-d 6 , elemental analysis and X-ray diffraction. The NMR data observed that the title compound exists in the enol tautomer rather than keto, and it stabilized by strong H-bond as observed form the NMR data at different temperatures. Theoretical calculations (DFT) were carried out using Gaussian09 program package and B3LYP correlation function. Full geometry optimization of the keto and enol forms were carried out using 6-311G++(d,p) basis set. The structure and energy of the transition state between these two tautomers were calculated. The frontier orbital energy and atomic net atomic charges of the tautomers were presented. The experimental results of the title compound have been compared with the theoretical results and it was found that the experimental data are in a good agreement with the calculated values. The transition state calculations also support the stability of enol form compared to keto form at room temperature.

Synthesis, Characterization, and Tautomerism of 1,3-Dimethyl Pyrimidine-2,4,6-Trione s-Triazinyl Hydrazine/Hydrazone Derivatives

“…The 13 C NMR for compound 4 also confirmed the enol form 4C rather than the keto form or the enol form 4B, where 13 C NMR showed peaks at 24.8 (CH 3 ), two peaks at 27.9 and 28.1 for the 2 N-CH 3 , 95.9 (C4=C-OH), 150.5 (C1), 161.0 (C5), 169.5 (acetyl C=O), and 196.2 (C=C3-OH) (Supporting Information Figure S7 in Supplementary Material). This observation is in agreement with the reported data by Sharma et al [38] and Giziroglu et al [39].…”

Exploiting the Thiobarbituric Acid Scaffold for Antibacterial Activity

“…Satisfactory yields of compounds A08 and A09 were obtained, respectively (Scheme ). The spectral data confirmed their enamine structures rather than imine structures, which were in good agreement with the reported data …”

“…This might be due to the lower activity of benzoic anhydride compared to acetic anhydride. A01 and A02 crystallized in their enol forms (crystallization of A03 was not attempted), as shown by 1 H NMR (experimental section) and as reported earlier by our group for barbituric derivatives …”

“…Acylation : Although BA acetylation can be achieved by several methods, there is no appropriate or concrete evidence of TBA acetylation. Using DETBA as the substrate, acylation of TBA with acetic/propionic anhydride was performed following our previously reported method for BA with slight modifications (Scheme ). The use of aqueous media for this reaction and a small excess of anhydride is an advantage over the previously reported method .…”

Crystal structure, spectroscopic studies and theoretical studies of thiobarbituric acid derivatives: understanding the hydrogen-bonding patterns

“…Frontier orbital energy analysis and molecular total energies. Molecular total energy and frontier orbital energy levels were calculated using DFT (Table 5), as discussed previously by our group (Sharma et al, 2017).…”