Dual C–F/C–H functionalization unveiled

In an effort to develop a general method for making multifluorinated biaryl compounds, a pair of chemists has achieved the first example of a direct cross-coupling reaction between a C–F bond of one aryl compound and a C–H bond of another aryl compound without having to first prefunctionalize either of the aryl coupling partners like in traditional cross-coupling strategies (J. Am. Chem. Soc. 2016, DOI: 10.1021/jacs.5b13450). Sameera Senaweera and Jimmie D. Weaver of Oklahoma State University, Stillwater, previously determined how to use an iridium photocatalyst with amine reductant to selectively functionalize a C–F bond of multifluorinated aryl compounds. Along the way they realized there was an opportunity to go further with the perfluoroaryl radical intermediate and use it to couple with a nonfluorinated aryl partner if they could create the right reaction conditions. Starting from pentafluoropyridine, they found that the iridium catalyst with a bulky amine under blue LED light works, leading to a wide array of multifluorinated biaryl compounds (one example shown) that are typically useful in drugs, agrochemicals, and electronic materials. “We believe that, even though some of the yields are modest, the fact the reaction takes place in a single step from two broadly available partners and tolerates a broad range of functionality really gives this method legs,” Weaver says.