Abstract The recyclization of 1, 4-dihydropyridines in aqueous-alcoholic hydrochloric acid medium proceeds with cleavage of a CN bond and pyridine ring opening. Cyclohexenone derivatives are formed as a result of the subsequent intramolecular crotonic condensation of the acyclic intermediate. The leaving carbonyl substituents depart simultaneously with recyclization, depending on the acidity of the reaction medium.
