Conformational behaviour and [formula omitted]/ [formula omitted] isomerization of [formula omitted]-acyl and [formula omitted]-aroylhydrazones

Abstract

The stereochemical behaviour of N -acyl and N -aroylhydrazones of aromatic aldehydes, of pyruvates and of acetone, in polar and less polar solvents, has been studied by HPLC and by NMR techniques. Z/E Geometrical isomers and cis / trans amide conformers have been found for N -acylhydrazones, while for N -aroylhydrazones only geometrical isomers were detected. Energy barriers of isomers are reported, and solvent effects are discussed with regard to hydrogen bond interactions.