title: Computational Characterization of the Origin of Selectivity in Cycloaddition Reactions Catalyzed by Phosphoric Acid Derivatives.
abstract: The mechanism of the organocatalyzed [4+2] cycloaddition of ο-hydroxybenzaldimines to 2,3-dihydro-2 H-furan (DHF) to form furanobenzopyrans has been investigated by using computational methods. Experiments have shown that this reaction produces different products (trans-fused or cis-fused) if different phosphoric acid derivatives are applied. Our study shows the reaction proceeds through a mechanism in which the imine re-arranges into an amine, which subsequently reacts with DHF with mediation from the catalyst. The rate-limiting step in this process is the formation of two new bonds, which is also the key step in determining the reaction selectivity. The selectivity is controlled by a balance of noncovalent interactions between the catalyst and the substrates. The discriminating factor between the two catalysts is the presence of a triflyl substituent on one of catalysts, which constraints the relative orientations of the substrates.
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Avgda. Països Catalans, 16, 43007, Tarragona, Catalonia, Spain.|School of Chemistry and Chemical Engineering, Xuchang University of China, No. 88 Bayi Road, Xuchang, Henan, 461000, P. R. China.
authors.forename: Chunhui
authors.initials: C
authors.lastname: Liu
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Avgda. Països Catalans, 16, 43007, Tarragona, Catalonia, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Besora
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Avgda. Països Catalans, 16, 43007, Tarragona, Catalonia, Spain.|Departament de Química, Universitat Autònoma de Barcelona, 08193, Bellaterra, Catalonia, Spain.
authors.forename: Feliu
authors.identifier: http://orcid.org/0000-0001-8806-2019
authors.initials: F
authors.lastname: Maseras
keywords: computational chemistry; cycloaddition; density functional theory; organocatalysis; phosphoric acid esters