Conformational and configurational analysis of an N,N carbonyl dipyrrinone-derived oximate and nitrone by NMR and quantum chemical calculations

Marauo Davis, University of Southern Mississippi
Liu Yang, University of Southern Mississippi
Yong Zhang, University of Southern Mississippi
Michael T. Huggins, University of Southern Mississippi

Abstract

The geometries and relative energies of new N,N carbonyl dipyrrinone-derived oxime molecules (E/Z-s-cis 4a and E/Z-s-cis 4b) have been investigated. The calculated energies, molecular geometries, and H-1/C-13 NMR chemical shifts agree with experimental data, and the results are presented herein. The E-s-cis conformations of 4a and 4b and the Z-s-cis conformation of 5b were found to be the thermodynamically most stable isomers with the oxime hydrogen atom or the methyl functional group adopting an anti-orientation with respect to the dipyrrinone group. This conformation was unambiguously supported by a number of 2D NMR experiments. Copyright (C) 2011 John Wiley & Sons, Ltd.