Direct Electrophilic α-Fluorination of Imines: Efficient Synthesis of Mono- and Difluoroimines

[reaction: see text] A mild and efficient procedure to synthesize alpha-fluoro- and alpha,alpha-difluoroimines was developed. Various N-alkylimines derived from acetophenones were successfully monofluorinated using NFSI (N-fluorobenzenesulfonimide) in a mixture of CH(3)CN and DMF at 0 degrees C. Alternatively, the same procedure without DMF gave rise to difluorinated imines when performed at room temperature. The obtained alpha- and alpha,alpha-difluorinated imines were subsequently reduced to give the corresponding beta-fluoro- and beta,beta-difluoroamines in good yield.