Weak coordination

I was looking at my Papers3 collection today (those of you who have a Mac and do not have this software – get it right now, while those of you who have a PC – well, I am sorry…) for some non-coordinating anion chemistry. I came across an old paper by my good friend Sergey Kozmin of the University of Chicago, who explored the powerful properties of HNTF2 acid in catalysis. The reaction you see below is one of the examples in the fascinating segment of synthesis where triflamide anion plays its pivotal role. Incidentally, the chloride substituent in the product does come from dichloromethane, so check out the mechanism.

iii

http://pubs.acs.org/doi/abs/10.1021/ja055054t

Lewis acid catalysis is another area where triflamide anions have been put to good use. The link below describes the work of Niggemann and co-workers, who have developed a very unusual set of conditions that call for the use of calcium triflamide in conjunction with tetrabutylammonium hexafluorophosphate (this combo is now available from Sigma-Aldrich, so I want to check it out in our own work). The central role of the non-coordinating triflamide anion is on display in this reaction as well. What else might we think about? Perhaps electrophilic fluorinating reagents of the Tf2NF class come to mind, plus some other applications? The bottom line is that non-coordinating anions offer a rich area for exploration because they do not meddle in polar reactions that occur in their vicinity.

Image

http://pubs.acs.org/doi/abs/10.1021/ol400341p

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