Abstract
N-Alkyl pyridinium () and N-alkyl isoquinolinium salts V undergo cyclization reaction when heated with sodium bicarbonate to give the corresponding indolizine derivatives and , respectively, which undergo ring opening and recyclization reactions when heated with aqueous sodium hydroxide to give the corresponding indole derivatives and , respectively. Molecular modeling tools including Molecular Mechanics using Augmented MM3 parameters followed by geometry optimization calculations in MO-G using PM3 parameters were performed to gain better understanding and more insights on the thermodynamic properties of the recyclization reactions of compounds to the corresponding and to the corresponding . The results were in excellent agreement with the experimental data and hence were proven to be a good tool in explaining different yields % because of the steric and electronic effects of electron-withdrawing groups on the reactivity of the pyridine ring for nucleophilic attack.