Stereoselective Synthesis of Di- and Monofluoromethylated Vicinal Ethylenediamines with Di- and Monofluoromethyl Sulfones

The diastereoselective nucleophilic (phenylsulfonyl)difluoromethylation and (phenylsulfonyl)monofluoromethylation
of α-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 α-difluoromethylated or α-monofluoromethylated ethylenediamines in good yields.