Palladium-Activated Fluoroform

Trifluoromethane (CHF₃), also known as fluoroform or HFC-23, is a large-volume side product of fluoropolymer production. Although the compound is ozone-friendly, it’s a potent greenhouse gas that manufacturers must pay to destroy. Chemical firms would like to repurpose CHF₃ as an inexpensive feedstock for fluorinated pharmaceuticals and agrochemicals. But chemists need efficient methods to activate CHF₃’s strong and poorly reactive C–H bond. Researchers recently discovered zinc-, copper-, and iridium-mediated CHF₃ reactions. Shin Takemoto (visiting from Japan’s Osaka Prefecture University) and Vladimir V. Grushin of the Institute of Chemical Research of Catalonia, in Spain, continuing Grushin’s work on copper, now report the first example of CHF₃ activation with palladium(II) (J. Am. Chem. Soc. 2013, DOI: 10.1021/ja409533s). The phosphine-catalyzed reaction leads to aryl PdCF₃ complexes via an unprecedented mechanism that involves hydrogen bonding between PdO(H) and H–CF₃. Considering that palladium is one of the few metals that can promote aryl-CF₃ bond formation, the work “will likely lead to further developments in the area of aromatic trifluoromethylation,” the researchers write.