Ammonium Bromides/KF Catalyzed Trifluoromethylation of Carbonyls

Significance

The authors report a catalytic tri­fluoromethylation protocol of aldehydes, ketones, and imides which uses inexpensive tetrabutyl­ammonium bromide (TBAB) and KF to activate Me₃SiCF₃. This system tolerates a wide range of aromatic, alkyl, and conjugated aldehydes as well as cyclic and acylic ketones and cyclic imides. ­Additionally, toluene, CH₂Cl₂, MeCN, and THF could all be used as solvents. Chiral ammonium salts were then screened in this reaction. With 2-naphth­aldehyde as test substrate, cinchona alkaloid 1 was found to give the corresponding alcohol in 40% ee.