DFT study of the molecular structure of 3,4-dihydropyrimidin-2(1H)-ones

Density functional theory at B3LYP/6-31++ G(d,p) level was applied to study structural, electronic, and bonding characteristics of some 3,4-dihydropyrimidin-2(1H)-ones substituted at C4 position (DHPMs) of pharmaceutical interest. Results of this study show that in these DHPMs the six-membered ring adopts a pseudo-boat conformation with a pseudo-axial orientation of the C4 substituent, and the heights of the C4 and N4 atoms from the boat plane depend on the type and position of the substituent on the aryl ring. Thermochemical analysis of these DHPMs and their corresponding oxidation products shows that the enthalpy of the oxidation reaction depends on the nature of the substituent at the C4 position, falling in a range of 25 kJ/mol for all compounds.