Conformational Properties of Novel 1,2,3,4-Tetrahydro- pyrimidinone (thione) Derivatives: A DFT study

Thirty nine novel 1,2,3,4-tetrahydropyrimidinone (thione)s were subjected to conformational studies. Density functional theory at B3LYP/6-31 G* was performed as the computational method of high accuracy. Important dihedral angles and bond lengths were investigated and the values obtained were explainable. Results of this work confirm a twisted boat tetrahydropyrimidine ring conformation with an axial C4 substituent for most of the compounds. This substituent was oriented toward the C5 atom. The carbonyl group located on the C5 substituent and the C5=C6 bond had both s-cis and s-trans conformation in the studied molecules.