Hi!
I would like to know if anyone has ever had success with the microwave promoted pyridine*HCl demethylation depicted in
https://www.thevespiary.org/rhodium/Rhodium/pdf/ether.cleavage.py-hcl.mw.pdf
on vanillin? The only thing I was able to find about it was a side note, telling that someone once tried it without success (here:
Post 508710
(Cadenza: "microwave type etc.", Chemistry Discourse)). He did use a modified mw oven, reflux setup and looong reaction times, though.
I just wondered because the paper seems to state that virtually
every substituent on the phenyl is possible
without interfering with the ether deprotection - but they use pulse irradiation (8 x 2 minutes at "medium low" in a standard domestic mw oven) and suggest using a stoppered vessel, rather than a reflux condenser.
Now without criticizing Cadenza, but maybe he just did run the reaction too long? Or maybe his problem was the everything else than inert atmosphere?
If you have any ideas about why the mentioned demethylation could NOT work with vanillin, I would be eager to hear them too (is vanillin somewhat hindered, compared to the substrates the authors of the article chose?)
TIA for answering my newbee questions!
indole_amine