Sterically controlled population of the 1,2-cis-form of 1,2-dimethyl-3-tert-butyldiaziridine

1,2-Dimethyl-3-R-diaziridine (R = Bu^t) has been synthesized for the first time; as revealed by NMR the population of its 1,2-cis-form was shown to increase in polar solvents [1,2-cis/1,2-trans = 2 (D₂O), 0.5 (CDCl₃), 0.03 (C₆D₆); for 1,2-trans →1,2-cis in C₆D₆ at 32 °C ΔG^# = 25 kcal mol⁻¹] whereas solely the 1,2-trans-form was detected in diaziridines when R = Me, Et, Prⁱ, Ph.