E-Z ISOMERISM OF ANILINOMETHYLENEMALONIC ACID-DERIVATIVES

The temperature and concentration dependence of the H-1 NMR spectra of four anilinomethylenemalonic acid derivatives were determined in CDCl 3 and DMSO-d6 to assign the E-Z isomers and to investigate the formati on of intra- and intermolecular hydrogen bonds. Chemical shifts and co upling constants in the C-13 NMR spectra correspond with the results o f the H-1 NMR investigations in the case of the cyanoacetate ester der ivative. Contradictory results for the acetoacetate derivative were fo und by semi-empirical calculations.