Novel Synthesis of Chiral Unactivated 2-Aryl-1-benzylaziridines

Chiral (R-S,R)- and (R-S,S)-N-(tert-butylsulfinyl)-2-aryl-aziridines were transformed into (R)- and (S)-2-aryl-1-benzylaziridines via a short three-step procedure. Deprotection and ring opening of (R-S,R)- and (R-S,S)-N-sulfinyl-2-arylaziridines (95-99% de) in acid medium afforded 2-aryl-2-chloroethylamine hydrochlorides in high yield (83-90%). These intermediates were converted into the corresponding chiral N-(benzylidene)-beta-aryl-beta-chloro-amines in good yield (78-85%). Subsequent reduction of the synthesized aldimines afforded chiral 2-aryl-1-benzylaziridines in good to excellent yield (74-94%) and enantiomeric excess (83-99% ee). The enantiomeric purity of the chiral aldimines and aziridines was established by NMR spectroscopy using Pirkle alcohol as the chiral solvating agent.