2. I actually meant AAC2, but I now realize this seems to be something SN1 based. AAL1 or maybe AAC1. Bot the tertiary/benzylic carbocation formed in AAL1 and the acyl cation formed in AAC1 look pretty good to me, and the strong acid seems to be favourable to both mechanisms.
Right idea. Which of those two carboctaions is more stable? Consider the effect that conjugation to heteroatom lone pairs, inductive effects and hybridisation have on of carbocation stability. One looks substantially more stable than the other to me.
What will the reaction look like if the ring is kept closed? I made a quick sketch of the best I could come up with (part a of the image below). Does it look okay? What worries me a bit is that we i) seem to have more steric hindrance in both the SEAr steps if we keep the ring closed and ii) don't seem to have any resonance stabilization from the oxygen in the same way as we had above. But maybe the carbocation still is stable enough?
Yes, your sketch is what I had in mind. Re: i) - a fair point, but it is still planar so I don't think it is such an issue. Re: ii) You can still use the lone pair of the lactone's endocyclic O to delocalise the charge (albeit less effectively), and you still have resonance stabilisation by the phenol and the aniline.
I fully concede that this could be wrong (see orgopete's post), but here is my reasoning: The two potential carbocations will be in equilibrium, it is a question of which is more likely to react with the aminophenol. I would predict that the lifetime of the ring-open carbocation is very short. Not because it is inherently unstable, but because the reverse reaction (intramolecular trapping with a pendant carboxylic acid nucleophile to form a 5-membered ring) will be very fast due to the permanent proximity of the carboxylic acid to the carbocation. On formation of the cyclic carbocation, the reverse reaction would be attack of water - water can diffuse away from the carboction, giving the arene nucleophile a higher probablility of colliding with it. I do think both mechanisms are plausible though.
3. Ah! I guess that's an especially stable resonance form? Is it stable enough to make the route below (part b of the image) available?
No, you're still jumping the gun here. That aryl carbocation is not resonance stabilised as the empty p orbital is orthogonal to the pi system (there is no overlap).
Draw the SE
Ar stepwise (you have not shown the mechanism in this step so far). When you get to the Wheland intermediate, deprotonation is normally the final step. Consider other possible avenues of reactivity for this intermediate.