A molecular electron density theory study of the competitiveness of polar diels–alder and polar alder-ene reactions

Luis R. Domingo, Mar Ríos-Gutiérrez, Patricia Pérez

Resultado de la investigación: Article

Resumen

The competitiveness of the BF3 Lewis acid (LA) catalyzed polar Diels–Alder (P-DA) and polar Alder-ene (P-AE) reactions of 2-methyl-1,3-butadiene, a diene possessing an allylic hydrogen, with formaldehyde has been studied within the Molecular Electron Density Theory (MEDT) at the MPWB1K/6-311G(d,p) computational level. Coordination of BF3 LA to the oxygen of formaldehyde drastically accelerates both reactions given the high electrophilic character of the BF3:formaldehyde complex. As a consequence, these reactions present a very low activation enthalpy—less than 2.2 kcal·mol−1—thus becoming competitive. In dioxane, the P-AE reaction is slightly favored because of the larger polar character of the corresponding transition state structure (TS). In addition, the Prins reaction between hexahydrophenanthrene and the BF3:formaldehyde complex has also been studied as a computational model of an experimental P-AE reaction. For this LA-catalyzed reaction, the P-DA reaction presents very high activation energy because of the aromatic character of the dienic framework. The present MEDT study allows establishing the similarity of the TSs associated with the formation of the C–C single bond in both reactions, as well as the competitiveness between P-AE and P-DA reactions when the diene substrate possesses at least one allylic hydrogen, thus making it necessary to be considered by experimentalists in highly polar processes. In this work, the term “pseudocyclic selectivity” is suggested to connote the selective formation of structural isomers through stereoisomeric pseudocyclic TSs.

IdiomaEnglish
Número de artículo1913
PublicaciónMolecules
Volumen23
Número de edición8
DOI
EstadoPublished - ago 2018

Huella dactilar

Alnus
Lewis Acids
Formaldehyde
Carrier concentration
Electrons
Cycloaddition Reaction
formaldehyde
Hydrogen
Diels-Alder reactions
dienes
Isomers
acids
Enthalpy
Theoretical Models
Activation energy
Chemical activation
Oxygen
Substrates
hydrogen
butadiene

Keywords

    ASJC Scopus subject areas

    • Analytical Chemistry
    • Chemistry (miscellaneous)
    • Molecular Medicine
    • Pharmaceutical Science
    • Drug Discovery
    • Physical and Theoretical Chemistry
    • Organic Chemistry

    Citar esto

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    title = "A molecular electron density theory study of the competitiveness of polar diels–alder and polar alder-ene reactions",
    abstract = "The competitiveness of the BF3 Lewis acid (LA) catalyzed polar Diels–Alder (P-DA) and polar Alder-ene (P-AE) reactions of 2-methyl-1,3-butadiene, a diene possessing an allylic hydrogen, with formaldehyde has been studied within the Molecular Electron Density Theory (MEDT) at the MPWB1K/6-311G(d,p) computational level. Coordination of BF3 LA to the oxygen of formaldehyde drastically accelerates both reactions given the high electrophilic character of the BF3:formaldehyde complex. As a consequence, these reactions present a very low activation enthalpy—less than 2.2 kcal·mol−1—thus becoming competitive. In dioxane, the P-AE reaction is slightly favored because of the larger polar character of the corresponding transition state structure (TS). In addition, the Prins reaction between hexahydrophenanthrene and the BF3:formaldehyde complex has also been studied as a computational model of an experimental P-AE reaction. For this LA-catalyzed reaction, the P-DA reaction presents very high activation energy because of the aromatic character of the dienic framework. The present MEDT study allows establishing the similarity of the TSs associated with the formation of the C–C single bond in both reactions, as well as the competitiveness between P-AE and P-DA reactions when the diene substrate possesses at least one allylic hydrogen, thus making it necessary to be considered by experimentalists in highly polar processes. In this work, the term “pseudocyclic selectivity” is suggested to connote the selective formation of structural isomers through stereoisomeric pseudocyclic TSs.",
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    A molecular electron density theory study of the competitiveness of polar diels–alder and polar alder-ene reactions. / Domingo, Luis R.; Ríos-Gutiérrez, Mar; Pérez, Patricia.

    En: Molecules, Vol. 23, N.º 8, 1913, 08.2018.

    Resultado de la investigación: Article

    TY - JOUR

    T1 - A molecular electron density theory study of the competitiveness of polar diels–alder and polar alder-ene reactions

    AU - Domingo, Luis R.

    AU - Ríos-Gutiérrez, Mar

    AU - Pérez, Patricia

    PY - 2018/8

    Y1 - 2018/8

    N2 - The competitiveness of the BF3 Lewis acid (LA) catalyzed polar Diels–Alder (P-DA) and polar Alder-ene (P-AE) reactions of 2-methyl-1,3-butadiene, a diene possessing an allylic hydrogen, with formaldehyde has been studied within the Molecular Electron Density Theory (MEDT) at the MPWB1K/6-311G(d,p) computational level. Coordination of BF3 LA to the oxygen of formaldehyde drastically accelerates both reactions given the high electrophilic character of the BF3:formaldehyde complex. As a consequence, these reactions present a very low activation enthalpy—less than 2.2 kcal·mol−1—thus becoming competitive. In dioxane, the P-AE reaction is slightly favored because of the larger polar character of the corresponding transition state structure (TS). In addition, the Prins reaction between hexahydrophenanthrene and the BF3:formaldehyde complex has also been studied as a computational model of an experimental P-AE reaction. For this LA-catalyzed reaction, the P-DA reaction presents very high activation energy because of the aromatic character of the dienic framework. The present MEDT study allows establishing the similarity of the TSs associated with the formation of the C–C single bond in both reactions, as well as the competitiveness between P-AE and P-DA reactions when the diene substrate possesses at least one allylic hydrogen, thus making it necessary to be considered by experimentalists in highly polar processes. In this work, the term “pseudocyclic selectivity” is suggested to connote the selective formation of structural isomers through stereoisomeric pseudocyclic TSs.

    AB - The competitiveness of the BF3 Lewis acid (LA) catalyzed polar Diels–Alder (P-DA) and polar Alder-ene (P-AE) reactions of 2-methyl-1,3-butadiene, a diene possessing an allylic hydrogen, with formaldehyde has been studied within the Molecular Electron Density Theory (MEDT) at the MPWB1K/6-311G(d,p) computational level. Coordination of BF3 LA to the oxygen of formaldehyde drastically accelerates both reactions given the high electrophilic character of the BF3:formaldehyde complex. As a consequence, these reactions present a very low activation enthalpy—less than 2.2 kcal·mol−1—thus becoming competitive. In dioxane, the P-AE reaction is slightly favored because of the larger polar character of the corresponding transition state structure (TS). In addition, the Prins reaction between hexahydrophenanthrene and the BF3:formaldehyde complex has also been studied as a computational model of an experimental P-AE reaction. For this LA-catalyzed reaction, the P-DA reaction presents very high activation energy because of the aromatic character of the dienic framework. The present MEDT study allows establishing the similarity of the TSs associated with the formation of the C–C single bond in both reactions, as well as the competitiveness between P-AE and P-DA reactions when the diene substrate possesses at least one allylic hydrogen, thus making it necessary to be considered by experimentalists in highly polar processes. In this work, the term “pseudocyclic selectivity” is suggested to connote the selective formation of structural isomers through stereoisomeric pseudocyclic TSs.

    KW - Diels-Alder reactions; Alder-ene reactions; competitive reactions

    KW - Molecular Electron Density Theory

    KW - Polar reactions; Prins reaction

    KW - Pseudocyclic selectivity

    UR - http://www.scopus.com/inward/record.url?scp=85052021556&partnerID=8YFLogxK

    U2 - 10.3390/molecules23081913

    DO - 10.3390/molecules23081913

    M3 - Article

    VL - 23

    JO - Molecules

    T2 - Molecules

    JF - Molecules

    SN - 1420-3049

    IS - 8

    M1 - 1913

    ER -