N-Heterocyclic Carbene Catalyzed Trifluoromethylation of Carbonyl Compounds

A novel N-heterocyclic carbene (NHC) catalyzed trifluoromethylation reaction of carbonyl compounds was discovered. Both enolizable and nonenolizable aldehydes and α-keto esters undergo facile trifluoromethylation with TMSCF₃ at room temperature in the presence of only 0.5−1 mol % of the commercially available NHC (1), providing CF₃-substituted alcohols in good yields. Selective trifluoromethylation of aldehydes over ketones can be achieved under NHC catalysis. These conditions are mild and simple and tolerate a variety of functional groups.