Organocatalytic asymmetric fluorination of α-chloroaldehydes involving kinetic resolution

In a previous study it was shown that the enantioselective alpha-fluorination of racemic alpha-chloroaldehydes with a chiral organocatalyst yielded the corresponding alpha-chloro-alpha-fluoroaldehydes with high enantioselectivity. It was also revealed that kinetic resolution of the starting aldehydes was involved in this asymmetric fluorination. This paper describes the determination of the absolute stereochemistry of a resulting alpha-chloro-alpha-fluoroaldehyde. Some information about the substrate scope and a possible reaction mechanism are also described which shed more light on the nature of this asymmetric fluorination reaction.