N-ACYL IMINE ENAMIDE TAUTOMERISM AND CONFORMATIONAL EQUILIBRIA OF METHYL 2-ACETAMIDOACRYLATE - AN AB-INITIO STUDY/

The N-acyl imine/enamide tautomerism of methyl 2-acetamidoacrylate, th e s-cis/s-trans conformational equilibria for both tautomers, and the E/Z isomerism for the imine form have been studied by means of ab init io calculations. Furthermore, the effects of BF3 and AlCl3 coordinatio n on these equilibria have been also investigated. For the enamide for m, the results indicate a preference for the s-trans conformation, whi ch is increased by linking of Lewis acids to the amide group. For the imine tautomer, the s-trans conformer is preferred for the isolated fo rm by a slight energy difference, although the coordination of Lewis a cids to the acetyl group slightly favours the s-cis conformation. In b oth isolated and coordinated imine molecules, the Z forms are more sta ble than the E isomers. The enamide form is preferred in tautomeric eq uilibrium, and its relative stability is increased by coordination of Lewis acids.