New class of bicyclic compounds derived from thiobarbituric acid with representative compound 1,3-diethyl-7-hydroxy-5,5,7-trimethyl-2-thioxo-1,2,3,5,6,7-hexahydro-4H-pyrano[2,3-d]pyrimidin-4-one. Preparation, crystal structure, mass spectrometry and IR sp

• The novel 2-thiobarbituric acid derivative containing bicyclic ring system is synthesized.
• The molecular and supramolecular structures of the compound are obtained.
• Mass spectroscopy and IR spectra measurements are carried out.
• A possible mechanism of the compound formation is proposed.
• Theoretical IR, EAS, HOMO–LUMO studies were made.

The colorless crystals of 1,3-diethyl-7-hydroxy-5,5,7-trimethyl-2-thioxo-1,2,3,5,6,7-hexahydro-4H-pyrano[2,3-d]pyrimidin-4-one (1) have been crystallized from the solution containing 1,3-diethyl-2-thiobarbituric acid (HDETBA) and equal volumes of concentrated HCl and acetone A possible stoichiometric reaction mechanism has been suggested. The crystal structure of 1 has been determined by X-ray single crystal analysis. The phase purity of the precipitate has been verified by powder X-ray diffraction analysis. Compound 1 crystallizes in the orthorhombic structure, space group P212121, with cell parameters a = 9.7454(4), b = 11.2225(4), c = 13.9171(5) Å, Z = 4, V = 1522.1(1) Å3. The molecules of 1 contain the bicyclic ring constructions new in thiobarbiturates. The molecules of 1 are linked by OH⋯O hydrogen bonds to infinite molecule chains. The results of mass spectrometric analysis, theoretical studies and IR spectroscopy confirm the structure of 1. Using the PASS software, the general pharmacological potential of 1 was analyzed.

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