Lithium Cation-Catalyzed Benzene Diels-Alder Reaction: Insights on the Molecular Mechanism Within the Molecular Electron Density Theory

Domingo, Luis R.; Perez, Patricia

Abstract

The lithium cation Li+-catalyzed Diels-Alder (DA) reactions of benzene toward a series of acetylenes of improved nucleophilicity can be described within the context of the molecular electron density theory (MEDT) at the omega B97XD/6-311G(d,p) level. Conceptual density functional theory indices characterize the crown ether solvated complex benzene-lithium Bz-Li-Cro as a superelectrophile. Coordination of a lithium cation to benzene does not change substantially the electron localization function electronic structure of benzene. The DA reaction of Bz-Li-Cro with acetylene shows a reduction of the energy of activation of 6.9 kcal.mol(-1), which is not sufficient for the reaction to take place, thus demanding the participation of strong nucleophilic acetylenes. DA reactions of complexes Bz-M-Cro (M = Li, Na, and K) are decelerated with the decrease of the ionization potential of the alkali metal. The one-step mechanism of these lithium cation Li+-catalyzed DA reactions changes to a two-step one for the reaction with dimethyl propynamine. The present MEDT study proves that analysis of the electrophilicity and nucleophilicity indices is an excellent tool for experimental organic chemists to understand, even to predict, the chemical organic reactivity.

Más información

Título según WOS: Lithium Cation-Catalyzed Benzene Diels-Alder Reaction: Insights on the Molecular Mechanism Within the Molecular Electron Density Theory
Título de la Revista: Journal of Organic Chemistry
Volumen: 85
Número: 20
Editorial: American Chemical Society
Fecha de publicación: 2020
Página de inicio: 13121
Página final: 13132
DOI:

10.1021/ACS.JOC.0C01801

Notas: ISI