DFT Treatment of Betazole Tautomerism

Abstract

Betazole belongs to pyrazole type medicines and selectively targets and binds to the H2-type receptors. Tautomerism can only be demonstrated in pyrazole derivatives and not in the pyrazole itself. In the present density functional treatment of tautomers of betazole (within the constraints of density functional theory) calculations have been performed at the level of B3LYP/6-311++G(d,p). Betazole may exhibit 1,3- and 1,5-type proton tautomerism involving pyrazole ring system so that in some tautomers aromaticity of the ring is destroyed. The results have revealed that all the tautomers possess thermo chemically favorable formation values at the standard conditions and are electronically stable. Some quantum chemical and spectral properties of those tautomeric systems as well as nucleus independent chemical shift (NICS) values for the aromatic ones have been obtained and discussed.