Conformational analysis about the N-N bond by N.M.R. spectroscopy: N'-sulphonyl derivatives of N-Aminobicyclo[2,2,1]hept-5-ene-endo-2,3-dicarboximide

Abstract

A series of N'-sulphonyl and N'-acyl derivatives of N-aminobicyclo[2,2,1]hept-5-ene-endo-2,3-dicarboximide have been synthesized and their conformations have been investigated by N.M.R.spectroscopy. The effect of the sulphonyl group at the exocyclic nitrogen on the conformational process about the N-N bond has been studied. Existence of non-planar ground states about the N-N bond in the N',N?-disulphonyl and N'-sulphonyl-N'-acyl derivatives has been demonstrated.Temperature-dependent spectral changes have been related to the conformational changes about the N-N bond. It has been shown that the N'-tosyl substituent assumes a preferred conformation about the N-SO₂ bond; the aryl part of the tosyl group lies exo to the cage-moiety. The N'-tosyl-N'-aroyl derivatives also show a preferred conformation about the N'-aroyl bond, the aryl part of the aroyl group lying endo to the cage-moiety. The N'-acetyl-N'-aroyl derivatives have been shown toexhibit low rotational barriers about the N'-aroyl bond.