Advances in the Transition Metal-Free C—H Trifluoromethylation

Trifluoromethyl group is one of the most frequently available and promising functional groups in pharmaceutical,agrochemical as well as material molecules.Developing synthetic methods for the synthesis of trifluoromethyl functionalized compounds by trifluoromethylation reactions occupies significant position in modern organic chemistry.On the other hand,as a typical tool of sustainable synthesis,transition metal-free synthesis possesses unique advantages in atom economy,easy product purification as well as excellent eco-tolerance.Consequently,transition metal-free trifluoromethylation reactions constitute the most important approaches for accessing trifluoromethylated molecules.Herein,the advances in the transition metal-free C—H trifluoromethylation reactions are reviewed for the first time.According to the updated state-of-art,both the catalytic reactions by conventional heating chemistry and the more sustainable photocatalysis are included,covering the trifluoromethylation reactions of C(sp^(3))–H bond,aromatic C(sp^(2))–H bond as well as the non-aromatic C(sp^(2))–H bond in different substrates over the last five years(2017—2021).