Theoretical and experimental (15)N NMR study of enamine-imine tautomerism of 4-trifluoromethyl[b]benzo-1,4-diazepine system.
The tautomeric structure of 4-trifluoromethyl[b]benzo-1,4-diazepine system in solution has been evaluated by means of the calculation of (15)N NMR chemical shifts of individual tautomers in comparison with the averaged experimental shifts to show that the enamine-imine equilibrium is entirely shifted toward the imine form. The adequacy of the theoretical level used for the computation of (15)N NMR chemical shifts in this case has been verified based on the benchmark calculations in the series of the push-pull and captodative enamines together with related azomethynes, which demonstrated a good to excellent agreement with experiment.
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Favorsky St. 1, 664033, Irkutsk, Russia.
Valentin A
VA
Semenov
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Favorsky St. 1, 664033, Irkutsk, Russia.
Dmitry O
DO
Samultsev
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Favorsky St. 1, 664033, Irkutsk, Russia.
Alexander Yu
AY
Rulev
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Favorsky St. 1, 664033, Irkutsk, Russia.
Leonid B
LB
Krivdin
15N NMR; GIAO-DFT; chemical shift; enamine-imine tautomerism; enamines; shielding constant; trifluoromethyl[b]benzo-1,4-diazepines