In asymmetric trifluoromethylation the trifluoromethyl group is added to the substrate in an enantioselective way. Ruppert's reagent has been used for this purpose in an asymmetric induction approach to functionalise chiral amino acid derivates, saccharides, and steroids.
Because Ruppert's reagent requires a tetraalkylammonium fluoride, chiral ammonium fluorides have been employed in asymmetric catalysis.
In the field of electrophilic trifluoromethylation an early contribution involved reaction of a metal enolate with a trifluoromethyl chalcogen salt in presence of a chiral boron catalyst.
More recent examples of highly enantioselective methods for the α-trifluoromethylation of carbonyls are available through enamine catalysis of aldehydes (photoredox or iodonium), copper catalysis of β-ketoesters, and radical addition to zirconium enolates.