Stereoselective Synthesis of Chiral Amino Allenes by Organocopper-Mediated anti-SN2′-Substitution Reaction of Chiral Ethynylaziridines

Chiral N-protected amino allenes have been synthesized from 3-alkyl-2-ethynylaziridines via organocopper-mediated reactions. Treatment of enantiomerically pure (2R,3S)-2,3-trans-3-alkyl-2-ethynylaziridines with RCu(CN)M (M=Li or MgX) in THF at −78°C affords exclusively the expected (S,S)-amino allenes in high yields in a regio- and stereoselective manner. On the other hand, (2S,3S)-2,3-cis-3-alkyl-2-ethynylaziridines give stereoisomeric (S,R)-amino allenes in comparable high yields.