Zusammenfassung
The preferred conformations of the enamine 1 and the hydrazones 3, 4, and 5 (prepared for the first time) were determined by 1H n.m.r. spectroscopy. The amino groups of these compounds are coplanar with the cyclohexadienone ring. The spectra at various temperatures yield information concerning the barriers of intramolecular motions at the C=CH–N̄ and C=N̄–N̄ system (Table 2). The low barrier to ...
Zusammenfassung
The preferred conformations of the enamine 1 and the hydrazones 3, 4, and 5 (prepared for the first time) were determined by 1H n.m.r. spectroscopy. The amino groups of these compounds are coplanar with the cyclohexadienone ring. The spectra at various temperatures yield information concerning the barriers of intramolecular motions at the C=CH–N̄ and C=N̄–N̄ system (Table 2). The low barrier to rotation about the C=CH bond and the high =CH–N̄ barrier in the enamine 1 prove that resonance structures 1aas well as1b contribute to the ground state; the corresponding results for 3, 4, and 5 in Table 2 do not show any considerable contribution of b. The reason for this difference is discussed. – 1, 3, 4, and 5 are protonated at the oxygen atom to the imonium and diazenium ions 8, 9, 10, and 11, respectively.
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