the aziridine nitrogen lone-pair has been considered: dynamics at the aziridine nitrogen as well as complex-inducedproximityeffects seem to be responsible for the observed regioselectivity in both monophenyl and diphenylaziridines. It turns out that, by tuning the reaction conditions for the lithiation of trans-1-alkyl-2-methyl-3-phenylaziridines, it is possible to generate with high regioselectivity