Direct Asymmetric α‐Fluorination of Aldehydes

Linear and branched aldehydes are asymmetrically α-fluorinated with L-proline- and pyrrolidine-based organocatalysts (see scheme; NFSi: N-fluorobenzenesulfonamide). In the first case, yields and enantioselectivities were high; in the second, the yields remained high and the enantioselectivities were moderate. Significantly, linear aldehydes were only monofluorinated.