CONFORMATIONAL BEHAVIOR OF SOME TRIFLUOROENAMINONES BY MULTINUCLEAR MAGNETIC-RESONANCE

The structures of 4-N-methylamino and 4-N,N-dimethylamino-1,1,1-trifluorobut-3-en-2-one (1, 2) were solved by means of an analysis of H-1,H-1 and H-1,C-13 coupling constants, NOE measurements, C-13,H-1 heteronuclear correlation and selective decoupling. The spectra of 1 are strongly solvent dependent. Variable-temperature experiments indicated that in these compounds the double bond character of the C-N bond is fairly pronounced and that the p-electrons from the nitrogen atom are engaged in the conjugated pi-electron SySteM. N-14, N-15, O-17 and F-19 chemical shifts for 1 are reported.