Methyl 2-trifluoromethylaziridine-2-carboxylate: stereodirected N-halogenation from the sterically more hindered side

N-Fluorination and N-chlorination of methyl 2-trifluoromethylaziridine-2-carboxylate occurs predominantly from the more hindered side owing to the fixed orientation of the lone electron pair of the N atom caused by the formation of an intramolecular H-bond.