Amino allenes have been synthesized from 2-ethynylaziridines via organocopper-mediated reactions. Whereas treatment of enantiomerically pure (2R,3S)-2,3-trans-3-alkyl-2-ethynylaziridines with RCu(CN)M (M = Li or MgX) yield exclusively (S,S)-allenylamines in high yields, isomeric (2S,3S)-2,3-cis-3-alkyl-2-ethynylaziridines afford (S,R)-allenylamines in comparable high yields. (C) 1998 Elsevier Science Ltd. All rights reserved.