Cyclocondensation reactions of 4-R-benzylidene-4-phenylbenzoylacetonitriles with cycloalkanones

Abstract

Cyclocondensation of 4-R-benzylidene-4-phenylbenzoylacetonitriles I with cycloalkanones II in the presence of ammonium acetate gives 4-aryl-2-(4-biphenylyl)-3-cyanocycloalkeno[b]pyridines IV-VI. A detailed study of the reaction course of cyclohexanone (IIa) with the ketonitriles Ia-Ij has shown that the bicyclic 1,4-dihydropyridine derivatives III, which easily undergo oxidation with air oxygen, are the intermediates in the formation of the heteroaromatic compounds IV. A mechanism is suggested for the reaction, and the dependence is discussed between structure of the synthetized compounds III-VI and their spectral properties.