1, 3: X= O 2, 4: X 2 NS02Ph a: R= Me b: R Et trogen proceeds most easily in the planar transition state of nitrogen inversion. Apart from theoretical considerations (increased ring strain, favorable steric and stereoelectronic conditions), this hypothesis was based3 on experiments described by Gaertner5 and on a reactivity comparison3p6 of aziridines with cyclopropanes possessing similar strength of activation, Le., similar basicity of their ...