fireoncells
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Bromination of thiazoles - quite problematic
Hello !
I am a student of pharmacy and doing some research in thiazole chemistry. I have to brominate 1-(2-(pyridin-4-yl)thiazol-5-yl)ethanone to obtain the
corresponding bromoketone. I've tried this with elemental bromine in CCl4 (stirring, r.t) and obtained a red powder after vacuum filtration . The
problem is that this molecule has to 2 aromatic N atoms and the bromine is actually incorporated into the molecule (probably like in pyridinium
tribromide?). The 1HNMR spectra shows that there has no bromination occured.
I have tried to brominate it with NBS/CCl4 + 2 drops HCl conc under reflux. TLC shows that the bromination is incomplete.
I don't like CCl4 at all-it is toxic and it doesn't work  si I have to try some
other system like NBS/MeCN or NBS/DMF with an appropriate catalyst. One of them is HBr but I don't have HBr so I have to make it.
So my questions are: Which is the best method to brominate this molecule with pronounced basicity (no Br2 please !  ) ), how to isolate the product (in base form not pyridinum salt) and how to make an
HBr solution. I've thought of S oxidation with Br2/H2O...any idea?
Sorry for my English...Thank you very much !
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dubei
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Solvent：Acetonitrile
with NBS
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Dr.Bob
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There are two ways to consider this. If the pyridine is the issue, make the N-oxide and ignore it until the chemistry is done, then reduce it back.
Or just look for routes that will work with pyridines. Here are a few methods that work with thiazoles, so they would likely work with the N-oxide,
and also some methods that work with pyridines. Good luck.
Attachment: bromoketonepyridine.pdf (158kB)
This file has been downloaded 432 times
Attachment: bromoketonethaizole.pdf (74kB)
This file has been downloaded 431 times
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