Mechanisms for the formation of five-membered rings in ethene addition reactions with azomethine ylide and allyl anion

• Published in: Chemistry of heterocyclic compounds (New York, N.Y. 1965) N.Y. 1965), 2016-09, Vol.52 (9), p.700-710
• Main Authors: Kletskii, Mikhail E., Burov, Oleg N., Fedik, Nikita S., Kurbatov, Sergey V.
• Format: Article
• Language: English
• Subjects: Alkenes; Anions; Chemistry; Chemistry and Materials Science; Cycloaddition; Ethylene; Organic Chemistry; Pharmacy; Pi-electrons; Schiff bases
• ISSN: 0009-3122; 1573-8353
• DOI: 10.1007/s10593-016-1952-1

The mechanisms of pyrrolidine and cyclopentyl anion formation in the ethene addition reactions to allyl anion and azomethine ylide, as well as to their derivatives with π-electron-donating and π-electron-withdrawing substituents was studied for a wide range of systems by ab initio calculations using the MP2/6-311++G(d,p) basis set. The calculations showed that during the interaction of allyl anion with ethene the five-center intermediate species with C S symmetry was stabilized by direct π-electron donation effect, while in the case of azomethine ylide it was simultaneously affected by direct and reverse π-donation mechanisms. The introduction of π-electronwithdrawing substituents at the central position of allyl anion enabled a concerted synchronous cycloaddition process, while the reaction proceeded by single-step mechanism in the case of azomethine ylide having π-electron-donating or π-electron-withdrawing substituents at the nitrogen atom, except with sterically hindered reactants.