摘要:
The enamine derived from cyclopentanone and (2R,5R)-2,5-bis(methoxymethyl)pyrrolidine added ethyl N-mesylazidoformimidate [N3C(OEt)NMs] and ethyl azidoformate (N3CO2Et) with high asymmetric induction (>95%), while the corresponding cyclohexanone enamine gave ring contraction products. With the same azides the cyclopentanone enamine, prepared from (S)-2-(methoxymethyl)pyrrolidine gave N-substituted alpha-amino cyclopentanones in moderate enantiomeric excess. (C) 1997 Elsevier Science Ltd.