I was reading some reactions of ethers and I came across Zeisel determination. Later that day, I was asked to determine the products of the reaction :
And I made the product:
This reaction is standard Kucherov Reaction
Now my doubt is that ether linkage can get hydrolyzed under acidic conditions, so why can't the below product be formed?
Zeisel's method follows this mechanism, so then why can't it happen in this case?
The Zeisel reaction as described here reads like submitting the substrate to refluxing $\ce{HI}$ with $\ce{HOAc}$. This seems much more aggressive than the oxymercuration conditions in the first scheme, where you need a bit of $\ce{H+}$ to transfer the intermediate enol into the more stable ketone by keto-enol tautomerism. Compare e.g., with an entry on Organic Synthesis:
(credit to Org. Synth. 1973, 53, 94)
which, in the case of acetylenic bonds looks like this:
(credit to Wikipedia)
Thus, in your case:
My anticipation (though speculation) is, the reaction conditions to cleave off the methyl ether easily knock-down the enolizable ketone.
Demethylation of phenolic ethers generally requires some pretty extreme conditions. In verifying the structure of vanillin Tiemann and Haarmann (page 620) demethylated it successfully with dilute hydrochloric acid at up to 200°C. To illustrate the "usual" extreme conditions for demethylation, the authors first tried fuming hydroiodic acid at up to 130°C, but that gave an "amorphous, iodine-containing, black" decomposition product.
More recent work by Bomon et al. successfully used catalytic dilute HCl in an autoclave at up to 250°C to demethylate various phenolic ethers. The authors also give a very good review of demethylation reagents/techniques for comparison.
Funny how little has changed in those almost 150 years!
