Diazobicycloalkanes with bridgehead nitrogen atoms in nodal positions. 22. Conformational analysis of benzodiazabicycloalkenes. Iterative evaluation of spectral and thermodynamic parameters

Autor: Sal'nikov, G. E., Gall', A. A., Shishkin, G. V., Mamatyuk, V. I.
Zdroj: Chemistry of Heterocyclic Compounds; October 1991, Vol. 27 Issue: 10 p1130-1134, 5p
Abstrakt: 1H and 13C NMR were used to investigate the conformational equilibrium of benzo[f]-1,5-diazabicyclo[3,2.2]nonene and benzo[g]-1,6-diazabicyclo[4.2.2]decene in solution at temperatures from 20 to–110‡C. Benzo[f]-1,5-diazabicyclo[3.2.2]nonene in this temperature interval undergoes rapid conformational exchange, while the conformation ratio changes from 73:27 to 55:45. The thermodynamic characteristics of this equilibrium were obtained and some NMR parameters of the individual conformers were estimated. For benzo[g]-1,6-diazabicyclo-[4.2.2]decene it was possible to attain conditions of slow exchange between two conformations whose proportion in the temperature interval studied were almost identical. The kinetics of conformational exchange were investigated and the energy of activation of the process was found to equal 42.3 kJ/mole.
Databáze: Supplemental Index
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