Practical asymmetric synthesis of β-hydroxy-β-trifluoromethylated ketones via the first example of the in situ generation of trifluoroacetaldehyde and its successive asymmetric carbon-carbon bond formation reaction with chiral imines

Not only trifluoroactaldehyde ethyl hemiacetal or hydrate but also other polyfluoroalkylaldehydes acetals or hydrates react with an equimolar amount of various chiral imines, followed by hydrolysis to produce the corresponding (S)-beta-hydroxy-beta-polyfluoroalkyl ketones in good yields with good enantioselectivities; furthermore, the ee of the products can be improved by simple recrystallization.