[aldoxime_amine]

1 ---Thermolysis---> X -----Thermal reorganization----> Y ---tautomerization--> 2

Give the complete mechanism.

Maybe looks like a vinyl cyclopropane rearrangement fused with that nitrene intermediate. But I'm not able to obtain a 7 member ring...

[jpg28]

I tried solving it, and in the first part to remove the N₂ gas, I imitated the first part of Curtius Rearrangement. I think a pericyclic reaction may be involved in this, especially in the last part. I'm just not that sure of it, though. I can't seem to get the Nitrogen atom to get close to the carbonyl group...

[azmanam]

Is it really NH?  Maybe NMe?  There are 7 carbon atoms in the SM and only 6 in the pdt.

[aldoxime_amine]

Oh yea sorry 

The extra methylene group b/w the acyl and the azide shouldn't be there.

[azmanam]

ah, that helps a lot.  here's my hint: there's a 6-pi sigmatropic rearrangement that takes place.

[aldoxime_amine]

I guesses about the sigmatrpic rearrangement. But can you please expand?

[azmanam]

can you draw the mechanism for the generic sigmatropic rearrangement?

also, what reactions do you know involving acyl azides?

[jpg28]

Oh so that's why I can't get the Nitrogen atom to come close to the carbonyl group. 

Here's what I had in mind... I'm not pretty sure of my last line, though... Any comments on it would be highly appreciated.

P.S. I'm afraid that the image might be too large, I don't want to spam the board with this, though, and so I sincerely apologize...

[aldoxime_amine]

Thank you jpg, for that. So, it was simply a curtius rearrangement followed by the sigmatropic rearrangement?

[jpg28]

Well, I'm not really really 100% sure, especially for the last part. I just tried to provide a mechanism for the transformation. The first one imitates the initial part of a Curtius rearrangement, while the latter part involves a [3,3]-sigmatropic rearrangement. I am not 100% sure of the last part, however. But it seems possible for it to do that.

What's bothering me is the fact that the Nitrogen atom in the amide [in this case, the lactam] is not sufficiently basic enough, since it's included in the resonance. I just forced it to take the hydrogen atom to produce that product.

I've read a book about polarophile interactions (I believe this is still under pericylic reactions), and maybe the explanation for the last part lies in that. The book that I was referring to was Dr. Grossman's book on The Art of Writing Reasonable Organic Reaction Mechanisms (2e). Anyway, I hope that helped you in a small way.

[Squirmy]

What's bothering me is the fact that the Nitrogen atom in the amide [in this case, the lactam] is not sufficiently basic enough, since it's included in the resonance. I just forced it to take the hydrogen atom to produce that product.

I wouldn't think that lone pair would participate in resonance to any significant extent. More likely that the N=C is in resonance with the carbonyl...can't have both, though. It's analogous to how the lone pair on pyridine can't be part of the pi-system.

The only thing I would question about the mechanism is whether it's intramolecular, but the overall idea is fine.

[jpg28]

I wouldn't think that lone pair would participate in resonance to any significant extent. More likely that the N=C is in resonance with the carbonyl...can't have both, though.

That's a good argument, Squirmy. As of now, I'm still having doubts, most especially with that last part. Oh, and by the way, thanks for commenting on it.

[azmanam]

tautomerizations are rarely intramolecular.  but I wouldn't worry about that too much.  As said above, the nitrogen lone pair is orthogonal to the C=N-C=O conjugation.  Forget about the carbonyl, and it's just an imine/enamine tautomerization.  Plus the doubly allylic protons are especially acidic, helping with the tautomerization.

[jpg28]

Oh, so that's the reason for the last part then. Thank you for helping me understand that as well, azmanam.