Electronic control of stereoselectivity in the chlorination of 1,4-dihydro-1,4-iminonaphthalenes (7-azabenzonorbornadienes) with N-chlorosuccinimide

Graphic Chlorination of a range of secondary amines based on the 1,4-dihydro-1,4-iminonaphthalene (7-azabenzonorbornadiene) ring system is described. At low temperatures, the ratio of syn- and anti- N-chloroamines formed under conditions of kinetic control can be determined; this ratio is shown to be influenced substantially by variation in the electronic character of the aryl ring. At higher temperatures, inversion at nitrogen leads to different (thermodynamic) invertomer ratios which also vary as a function of substitution. Substituents in the aryl ring and in the bicyclic skeleton also influence the nitrogen inversion barrier.