Stereoselective Synthesis of Chiral Amino Allenes by Organocopper-Mediated anti-SN2′-Substitution Reaction of Chiral Ethynylaziridines
摘要:
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 degrees 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. (C) 2000 Elsevier Science Ltd. All rights reserved.
Two convenient methods for the synthesis of chiral 2-ethynylaziridines from natural α-amino acids are described. Sodium hydride-promoted aziridination of mesylates of 4-arylsulfonylamino-2-bromoalk-2-en-1-ols yields trans-2-(1-bromovinyl)aziridines in a highly stereoselective manner, and subsequent dehydrobromination of the aziridines by potassium tert-butoxide gives separable stereoisomeric mixtures
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 degrees 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. (C) 2000 Elsevier Science Ltd. All rights reserved.