The Palladium-Catalyzed Trifluoromethylation of Aryl Chlorides

Three Fluorines at Once The trifluoromethyl (CF 3 ) group is playing an increasingly important role in the design of pharmaceutical and agrochemical compounds. CF 3 is a powerful attractor of electron density within a given molecular framework, and recently fluorine-hydrocarbon interactions have emerged as a distinct complement to the more traditional hydrophilic/hydrophobic interplay that governs docking between small molecules and proteins. Cho et al. (p. 1679 ) now present an efficient method for appending CF 3 groups to a broad range of aryl substrates. A carefully optimized palladium catalyst was able to speed up a critical elimination step that has plagued previous efforts to realize a general solution to this synthetic challenge.