Hi,
have you ever encountered problems with traces of catalyst copper in drugs used tissue culture? The drug has been prepared via Cu-catalysed Click chemistry and purified by silica column chromatography.
Which method can you recommend to remove Cu traces?
Cheers,
Andreas
I have a bit of experience in Cu-catalysed Click-Chemistry. It's possible to use aqueous EDTA to wash the copper off your organic phase soluble product. Also, the more acidic the pH of the washing solution, the more likely you are to remove the copper since copper will easily be exchanged for a proton on the fifth position the triazole, thus decomplexing the copper. I too have also noticed that Click-Chemistry with Copper iodide often leaves traces of copper remaining with the product.
Keep in mind that the Cu(I) catalysed reaction with terminal alkyne can also generate byproducts via the Glaser coupling reaction in presence of trace amounts of oxygen.
In my case I have found that using Cu(II) (in the form of copper sulfate) reduced in situ in Cu(I) by sodium ascorbate yields a much more cleaner product than directly using Cu(I) as copper iodide. I also get better yield with this method, with almost quantitative yields instead of around 75 to 80% yields with copper iodide.
Have a look at my master thesis pages 33-40, p45-48 and also at p88 and later for my modus operandi. You can find it here on ResearchGate although keep in mind it's written in french.
Otherwise, there is also a very good article from Sharpless comparing Cu(I) versus in situ reduction of Cu(II) for proceeding to click chemistry. Here is the reference :
Rostovtsev, V. V., Green, L. G., Fokin, V. V. and Sharpless, K. B. (2002), A Stepwise Huisgen Cycloaddition Process: Copper(I)-Catalyzed Regioselective “Ligation” of Azides and Terminal Alkynes. Angewandte Chemie International Edition, 41: 2596–2599. doi:10.1002/1521-3773(20020715)41:143.0.CO;2-4
Research Synthèse de mannosides inhibiteurs de l'adhésion des souches...
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