In a post reviewing work done towards a total synthesis of Platensimycin, Paul Docherty of TotallySynthetic.com wonders if a fluorous separation could be used to remove the catalyst in this reaction:
They state that they tried a number of carbene-based catalysts, but found that the triazole catalyst shown was optimal. I noticed that the catalyst has a per-fluoro phenyl group bolted-on – does this mean they could use Curran’s fluorous phase chromatography to separate it with ease?
We talked about this at one of our recent literature meetings, and the consensus was that you might get some retention of the catalyst by loading onto a F-SPE cartridge and washing with 80:20 Methanol: Water, but it probably would not be completely retained. There’s not a lot of fluorine atoms, and, perhaps more importantly, salts can be problematic.
You could certainly use a fluorous PMB protecting group or a fluorous tin hydride (for a later reaction that is not shown) in other parts of the synthesis with great results, but the particular reaction pictured above would be difficult, unless one were to make a different carbene catalyst with more fluorous content. Hhhhmmm…