Hey all!
We tried a number of different solvents, but we cannot crystallize the final product. Any ideas?
Cheers,
High Pinar,
2-Bromoesters tend to be reactive, if "pushed" your amine may be cyclizing by substituting the bromine with nitrogen. I would presume that when you run the deprotection in, say, isopropanol with 3 equiv of HCl, at RT -> 45 degC, and then concentrate the mixture to about 4-5 volumes/expected product mass, put it in the refrigerator, you should see it crystallize. HBr might be a better acid to accomplish this (sometimes HBr salts, or methanesulfonic acid salts, tend to give better crystals).
Good luck.
From the original description of the problem it looks like a crystalline product is required. TFA salts, at least the few I have dealt with :), typically were viscous oils. Yet indeed, TFA, or TFA/CH2Cl2, are commonly used for Boc removal from amines at RT.
In addition organic salts like succinate, oxalate & citrate can be tried in IPA as solvent.
In my opinion, first added to a base/acid to labile for crystallization and........
more mixture of polar and non-polar solvents are useful by trial and error ways....?
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