Stereoselective synthesis of di- and monofluoromethylated vicinal ethylenediamines with di- and monofluoromethyl sulfones.

The diastereoselective nucleophilic (phenylsulfonyl)difluoromethylation and (phenylsulfonyl)monofluoromethylation of alpha-amino N-tert-butanesulfinimines (3) by using PhSO2CF2H and PhSO2CH2F reagents gave products 4 or 5 in high yields (73-99%) and with excellent diastereoselectivity (dr up to >99:1). After subsequent reductive desulfonylation and acid-catalyzed alcoholysis, compounds 4 and 5 could be readily transformed to chiral alpha-difluoromethylated or alpha-monofluoromethylated ethylenediamines in good yields.