Necessary Conditions for the πir-Electron Delocalization in Enamino-Type Muscle Relaxants

Two necessary conditions have been proposed for the π-electron delocalization across four bonds in bis-quaternary bromides of enamino spiro-ketal-type compounds.Dynamic NMR data analysis of these compounds suggests that π-electron delocalization takes place if the first atom is nitrogen and the fourth atom is either nitrogen or oxygen [i.e., N+=C—C=N (or O)].The second condition is that the end atoms of the four-bond system should not be the terminal group.