Conformational flexibility of the 1,4-dihydropyridine ring in calcium channel agonists and antagonists molecules

Conformational flexibility of the 1,4-dihydropyridine ring in 4-aryl derivatives of the 2,6-dimethyl-3,5-dicarbmethoxy-1,4-dihydropyridine has been studied using the MM3 molecular mechanics method. Change of the C=C---C---C= endocyclic torsion angle of dihydrocycle in the range of 35° entails an increase of energy less than 1 kcal mol⁻¹. The energy levels below 99% of the molecular population for each molecule were estimated. The interval of the torsion angle change for these regions is about 60°.