Dihydropyridines and pyridones from 3-cyano-1-methylpyridinium iodide in aqueous sodium hydroxide.

3-Cyano-1-methylpyridinium iodide added to aq. NaOH and stirred for 2 h gave the isomeric 1,4-, 1,2-, and 1,6-dihydropyridines in the ratio 11:2:1, 5-cyano-1-methyl-2-pyridone, and 3-cyano-1-methyl-2-pyridone which were extd. with CH2Cl2. The aq. layer, after neutralization with H2SO4, gave 2-cyano-glutaconaldehyde Na enolate, shown by NMR to exist in a mesomeric state. The intermediate 2-hydroxydihydropyridines behaved as reducing agents toward the pyridinium cation, involving H- transfer, as well as undergoing the normal ring opening reaction