The skies are leaden and we’re set for several days of rain. But the weather isn’t going to deter the thousands of chemists who’ve congregated here in Boston for this fall’s national ACS meeting. The technical program is particularly good this time round, so I’ve had some difficulty cherry-picking which seminars to attend.
I decided to kick off first thing on Sunday morning with an organic symposium held in memory of Keith Fagnou, who tragically died last year. Although the mood was inevitably somewhat sombre, the overall feeling was of a celebration of the chemistry that Keith loved. Indeed, much of the research discussed during the symposium had been influence by Keith’s work.
One theme that emerged was fluorination chemistry, an area that has seen some exciting developments recently – perhaps most notably with Steve Buchwald’s terrific paper in Science (see the abstract here) describing a catalytic cross-coupling process for attaching trifluoromethyl groups to aromatics. But Buchwald’s group is far from the only one developing this kind of reaction. John Hartwig described his work on the use of copper phenanthroline complexes for trifluoromethylation reactions. Although his reactions are currently stoichiometric, he pointed out that both the metal and the ligands are dirt cheap. The complexes can now be generated in situ in reactions, so I’ll watch with interest to see whether a catalytic version is forthcoming.
Melanie Sanford followed this up with two takes on the trifluoromethylation problem. Her first approach involves attaching perfluorinated alkyl radicals to aromatics. Although this works well for perfluorohexyl groups, currently it’s not so good for trifluoromethyl groups – but she’s confident that they’ll be able to optimize the trifluoromethylation reactions. Her second strategy is to use trifluoromethyl cations in cross-coupling reactions. The chief hurdle here is generating a catalytic cycle that has a high turnover number. Her group has now identified a catalytically competent, monomeric palladium(IV) compound for these reactions, a breakthrough that she hopes will overcome the turnover problem.
There’s lots more great chemistry on offer this week, so finding time to blog is difficult – but watch this space!
Andrew Mitchinson (Senior Editor, Nature)