[junjiefu]

In the attachement, you can see, N-methylpyridinium iodide is converted to 2-methyl pyridine and 4-methyl pyridine at high temperature.
My question is, how to explain the regioselectivity of this reaction? Why the methyl group is migrated to the α and γ positions of the pyridine ring?

Thanks!

[Babcock_Hall]

It is a forum rule (see red link) that you must provide your answer or give your thoughts before we can help you.

[junjiefu]

It is a forum rule (see red link) that you must provide your answer or give your thoughts before we can help you.

Sorry for disobeying the rule.

The only explanation I can conceive is that due to the mesomeric effect of the N-methylpyridinium, the α and γ positions are more electrically positive. Therefore, α and γ positions are more prone to be attacked by anion? But what anion attacks these positions? I don't think I^- can.

[kriggy]

What about alkyl shift?