Molecules 2012, 17(11), 13687-13703; doi:10.3390/molecules171113687
Article

On the Catalytic Effect of Water in the Intramolecular Diels–Alder Reaction of Quinone Systems: A Theoretical Study

Received: 18 September 2012; in revised form: 8 November 2012 / Accepted: 12 November 2012 / Published: 20 November 2012
(This article belongs to the Special Issue Diels-Alder Reaction)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: The mechanism of the intramolecular Diels–Alder (IMDA) reaction of benzoquinone 1, in the absence and in the presence of three water molecules, 1w, has been studied by means of density functional theory (DFT) methods, using the M05-2X and B3LYP functionals for exploration of the potential energy surface (PES). The energy and geometrical results obtained are complemented with a population analysis using the NBO method, and an analysis based on the global, local and group electrophilicity and nucleophilicity indices. Both implicit and explicit solvation emphasize the increase of the polarity of the reaction and the reduction of activation free energies associated with the transition states (TSs) of this IMDA process. These results are reinforced by the analysis of the reactivity indices derived from the conceptual DFT, which show that the increase of the electrophilicity of the quinone framework by the hydrogen-bond formation correctly explains the high polar character of this intramolecular process. Large polarization at the TSs promoted by hydrogen-bonds and implicit solvation by water together with a high electrophilicity-nucleophilicity difference consistently explains the catalytic effects of water molecules.
Keywords: intramolecular Diels–Alder reactions; polar Diels–Alder reactions; water catalysis; DFT reactivity indices; local reactivity difference index
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MDPI and ACS Style

Soto-Delgado, J.; Aizman, A.; Contreras, R.; Domingo, L.R. On the Catalytic Effect of Water in the Intramolecular Diels–Alder Reaction of Quinone Systems: A Theoretical Study. Molecules 2012, 17, 13687-13703.

AMA Style

Soto-Delgado J, Aizman A, Contreras R, Domingo LR. On the Catalytic Effect of Water in the Intramolecular Diels–Alder Reaction of Quinone Systems: A Theoretical Study. Molecules. 2012; 17(11):13687-13703.

Chicago/Turabian Style

Soto-Delgado, Jorge; Aizman, Arie; Contreras, Renato; Domingo, Luis R. 2012. "On the Catalytic Effect of Water in the Intramolecular Diels–Alder Reaction of Quinone Systems: A Theoretical Study." Molecules 17, no. 11: 13687-13703.

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