PerspectiveChemistry

Putting a Greenhouse Gas to Work

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Science  07 Dec 2012:
Vol. 338, Issue 6112, pp. 1298
DOI: 10.1126/science.1231092

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Summary

In 2011, 3 of the 10 best-selling pharmaceuticals and 7 of the 35 newly approved active ingredients were compounds bearing organofluorine groups such as trifluoromethyl (CF3) (1). Similar statistics hold for agrochemicals. Organofluorine groups confer useful properties such as high lipophilicity (and membrane permeability) and enhanced metabolic stability. The vast majority of methods for the introduction of CF3 groups are based on CBrF3 (either directly or as a starting material) and similar ozonedepleting substances that have their atmospheric emission strictly regulated by the Montreal protocol. Thus, new trifluoromethylating reagents are highly desirable. On page 1324 of this issue, Prakash et al. (2) report on direct nucleophilic trifluoromethylation reactions of a variety of silicon, boron, sulfur, and, most interestingly, carbon electrophiles using only stoichiometric amounts of CHF3 (fluoroform) facilitated by optimizing the base and solvent used in the reaction. This compound is actually an unwanted greenhouse-gas by-product from the production of fluoropolymers and refrigerants (see the figure).