Conformational equilibria and barriers to rotation in some novel nitroso derivatives of indolizines and 3- and 5-azaindolizines - an NMR and molecular modeling study.

Conformational equilibria in novel C-nitroso derivatives of indolizines and 3- and 5-azaindolizines have been studied by NMR. (13)C chemical shifts of the carbon alpha to the nitroso group confirmed that these compounds are present in solution as monomers. The conformers arising from restricted rotation about the C-NO bond in monomers were identified by the chemical shifts of the carbon beta to the nitroso group.