It was found that 1-methyl-3-methoxycarbonyl-1, 6-dihydropyridine was oxidized by KMnO4 into 1-methyl-5-methoxycarbonyl-2(1H)-pyridone in cold acetone in comparatively better yield. Following to this method, 2(1H)-pyridone compound was prepared from the corresponding 1, 4-dihydro compound but any pyridone compound 1-methyl-3-methoxy-carbonyl-1, 2, 5, 6-tetrahydropyridine did not undergo the oxidation in this condition.
