Free Radical-induced Oxidation Products of 3-Methyl-1-phenyl-2-pyrazolin-5-one (MCI-186)

Abstract

Free radical-induced oxidation of an anti-ischemic agent, 3-methyl-l-phenyl-2-pyrazolin-5-one (MCl-186) gave 2-oxo-3- (phenylhydrazono) -butanoic acid as the final product via 3-methyl-1-phenyl-2-pyrazolin-4, 5-dione and 4-hydroxy-4- (3-methyl-1-phenyl-2-pyrazolin-5-on-4-yl) -3-methyl-1-phenyl-2-pyrazolin-5-one as intermediates regardless of the free radical source. The mechanism for product formation is discussed.