Synthesis, crystal and molecular structure, vibrational properties, DFT and Hirshfeld surface analyses of ethyl 1-isobutyl-3,6-dimethyl-2,4-dioxo-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidine-5-carboxylate

Abstract

Thienopyrimidine derivatives exhibit extensive pharmacological properties in medicinal chemistry. In this study, ethyl 1-isobutyl-3,6-dimethyl-2,4-dioxo-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidine-5-carboxylate with a thienopyrimidine core is synthesized using a four-step reaction design. And subsequently characterized by 1H NMR, 13C NMR, FT-IR, and mass spectroscopy. Further, X-ray diffraction (XRD) is used to detect the single-crystal structure of the target compound, whereas the density functional theory is used to optimize its molecular structure. Evidently the calculated values and those obtained from the XRD are fully consistent. To further understand the physicochemical properties of the compound, its molecular electrostatic potential and leading edge molecular orbitals are determined. Finally, a reliable vibration assignment of the compound is performed according to the characteristic vibrational absorption band, and the atom-pair contacts of the crystal are explained by Hirschfeld surface analysis.