The compounds with trifluoromethyl group are ubiquitous in pharmaceuticals, agrochemicals and materials. Synthetic organic chemists are devoted to seeking efficient methods to integrate trifluoromethyl group into molecular frameworks and the discoveries of trifluoromethylating reagents. In this context, trifluoroacetic acid is undoubtedly an ideal alternatives due largely to their ready availability.

Prof. SU Weiping from Fujian Institute of Research on the Structure of Matter of the Chinese Academy of Sciences, in cooperation with Prof. LI Yadong from Tsinghua University, reported an effective method for direct C-H trifluoromethylation of nonactivated (hetero)arenes with trifluoroacetic acid under room temperature. The finding was published in Nature Communication.

The established approach employs cheap trifluoroacetic acid as trifluoromethyl reagent, clean light as an energy source, non-toxic and environmental friendly TiO₂ as a photocatalyst. What deserves to be mentioned is that a novel mechanism was proposed in this process based on detailed mechanistic investigation, in which no additional catalyst is involved, the proton in the reaction system act as oxidant to release hydrogen in the catalytic cycle.

This study demonstrated the unique potential of photocatalysis in the direct functionalization of C-H bonds without the addition of an oxidizing agent, and fully met the requirements of atomic economy.

This study was financially supported by the National Natural Science Foundation of China, the CAS/SAFEA International Partnership Program for Creative Research Teams and the Strategic Priority Research Program of the Chinese Academy of Sciences.