ASYMMETRIC FORMATION OF C-N BONDS IN CHIRAL ENOL ETHERS

Attack of EtO2CN on an enol ether carrying (S,S)-hydrobenzoin as chiral auxiliary gives diastereoselective aziridination with diastereomeric excess > 95%. Easy subsequent hydrolysis gives partially racemised alpha-amino ketone 4. Other chiral auxiliaries does not allow isolation of intermediate aziridines and the alpha-amino ketone is isolated with a 75:25 enantiomeric ratio. The thermolysis of EtO2CN3 in most of the same enol ethers gives the acetals of the alpha-amino ketone with prevailing opposite configuration at the new formed chiral centre.