Solvent and substituent effects on the conversion of 4-methoxypyridines to N-methyl-4-pyridones

In the reaction of 4-methoxypyridine derivatives with alkyl iodides in the presence or absence of solvent, not only the pyridinium ions but also the related 1-methylpyridones are produced. The presence of solvent favors the formation of the 1-methylpyridone. Electron withdrawing groups on the pyridine ring also favor this conversion. A possible mechanism is presented.