Metal-ion-facilitated oxidations of dihydropyridines with molecular oxygen and hydrogen peroxide

Abstract

Some bivalent metal ions such as alkaline-earth metal ions promoted the O₂- and H₂O₂-oxidations of 3,5-disubstituted 1,4-dihydropyridines in acetonitrile; particularly, the presence of Ca²⁺ in excess over the dihydropyridines completed these reactions within a few seconds, producing calcium hydroperoxide and hydroxide, respectively. The absorbance vs. time plot and the effects of various additives on these rates show that each reaction takes place through a free-radical chain mechanism.