An explanation for the apparent cis-aziridine selectivity in the iron Lewis acid-catalyzed reaction of N-benzylidene aniline and ethyl diazoacetate

The reason for the apparent cis-aziridine selectivity in the reaction of ethyl diazoacetate with N-benzylidene aniline, catalyzed by [(η5-C5H5)(CO)2Fe(THF)]+[BF4]−, is reported. The catalytic reaction produces both cis and trans-aziridines. Once the imine has been consumed, the trans-isomer is shown to undergo a catalytic decomposition, leaving cis-aziridine and by-products. The reaction is graphically profiled to illustrate the relative quantity of reactants and products as a function of time. A new mechanistic model is proposed in order to explain the observed selectivity.