N-heterocyclic carbene catalyzed trifluoromethylation of carbonyl compounds

reaction: see text]. A novel N-heterocyclic carbene (NHC) catalyzed trifluoromethylation reaction of carbonyl compounds was discovered. Both enolizable and nonenolizable aldehydes and alpha-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.