Electronic effects of substituents on the conformational characteristics of the 1,2-dihydropyridine ring

The electronic effects of substituents on the conformational characteristics of the 1,2-dihydropyridine ring were investigated by the MP2/6-31G(d) quantum chemical method. Introduction of a nitro group leads to a flattening of the ring; on the potential energy surface, the minimum corresponding to the conformer with an axial orientation of the NH hydrogen atom vanishes. An opposite tendency is observed in amino derivatives. Intramolecular interactions are analyzed to see how they affect the the equilibrium geometry and the energy characteristics of the dihydroheterocycle.