[kamel9898]

hello fellow chemists!
doing my masters studies i've encountered reaction shown below. i am having really hard times with coming up with a mechanism to it, thats why i thought posting it here would be a good idea.
i know the theory, i know what might happen (like starting with protonation of one carbonyl group etc) i just cant think of anything that would make the final product. probably its nothing hard and im just blind, but at this point i have really no idea



any help will be really appreciated

[Babcock_Hall]

It is a Forum rule that you must provide your thoughts before we can help you.  A good place to start is to show that protonation of the carbonyl group that you think is critical.  I would also think about electrophilic aromatic substitutions (one sees them not infrequently in forensics).  Just out of curiosity, is this a new reaction, or is this something well-known in forensic chemistry already?

[kamel9898]

not really new, just not often in use; derivatives of diphenylpyridine are used to identify impurities connected with the illegal metoxyamphetamine sources

tbh, i think i have something now and it seems legit, but without the electrophilic substitutions. im providing the decription below, although i think it might be a bit chaotic, sorry for that!

I protonated the ketone group, then nitrogen electron pair attacked the carbonyl carbon in order to remove the positive charge on oxygen. nucleophilic addition of water helped to remove positive charge on nitrogen. then i had some hydrogen migration in order to make amide and to protonate the 2nd ketone group and then the other positive charge was removed via cyclisation (water took one hydrogen). in the end i had simply 2x dehydratations under acidic conditions to form double bonds.

[Babcock_Hall]

https://doi.org/10.1016/j.forsciint.2004.07.018

I found a reference to the reaction, but I did not see a mechanism.

[rolnor]

https://en.wikipedia.org/wiki/Para-Methoxyamphetamine

It does seem like a really crappy drug....