n-Butyltriphenylphosphonium peroxodisulfate: A cheap and efficient reagent for the aromatization of Hantzsch 1,4-dihydropyridines

Different 4-substituted 1,4-dihydropyridines have been oxidized to pyridine derivatives by n-butyltriphenyl phosphonium peroxodisulfate in acetonitrile solution at reflux condition. Formation of two kinds of products has been observed depending on the type of 4-substituent.