A Theoretical Investigation of the Relative Stability of Isomeric Dihydropyridines

Abstract

The molecular structure and relative stability of isomeric dihydropyridines have been calculated using the density functional theory and the Moller–Plesset second order perturbation theory. The results of the calculations demonstrate that 3,4- and 2,3-dihydropyridines are the most stable species despite the presence of a 4π-electron conjugated system within the ring. A comparison of the relative energy of acyclic analogs of dihydropyridines indicates that this is caused by the internal properties of the conjugated system. The remaining dihydropyridines are strongly destabilized by the formation of antiaromatic conjugated (or quasi-conjugated) systems due to the interaction of pz atomic orbitals of the carbon and nitrogen atoms with the pseudo-π fragment orbital of the methylene group. Application of the more accurate CCSD(T)/CBS method results in considerable stabilization of 1,4-dihydropyridine. However, the order of stability of other isomers remains the same as it was found at the MP2 level of theory. How to Cite Shishkin, O. V.; Zubatyuk, R. I.; Desenko, S. M.; Leszczynski, J. Chem. Heterocycl. Compd. 2014 , 50 , 327. [ Khim. Geterotsikl. Soedin. 2014 , 357.] For this article in the English edition see DOI 10.1007/s10593-014-1480-9