Thiourea-catalyzed Diels-Alder reaction of a naphthoquinone monoketal dienophile

Lewis Acid-Catalyzed Diels-Alder Reactions: Reactivity Trends across the Periodic Table

The catalytic effect of various weakly interacting Lewis acids (LAs) across the periodic table, based on hydrogen (Group 1), pnictogen (Group 15), chalcogen (Group 16), and halogen (Group 17) bonds, on the Diels-Alder cycloaddition reaction between 1,3-butadiene and methyl acrylate was studied quantum chemically by using relativistic density functional theory. Weakly interacting LAs accelerate the Diels-Alder reaction by lowering the reaction barrier up to 3 kcal mol-1 compared to the uncatalyzed reaction. The reaction barriers systematically increase from halogen Collapse

Key Words

• Diels-Alder reaction
• Lewis acids
• activation strain model
• density functional calculations
• reactivity

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MESH Headings Collapse

Grants

• Netherlands Organization for Scientific Research (NWO)
• Dutch Astrochemistry Network (DAN)
• PID2019-106184GB-I00 Spanish MICIIN
• RED2018-102387-T Spanish MICIIN
• Nederlandse Organisatie voor Wetenschappelijk Onderzoek
• Dutch Astrochemistry Network
• Nederlandse Organisatie voor Wetenschappelijk Onderzoek

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Affiliation(s)

Pascal Vermeeren Department of Theoretical ChemistryAmsterdam Institute of Molecular and Life Sciences (AIMMS)Amsterdam Center for Multiscale Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdam (TheNetherlands
Marco Dalla Tiezza Department of Theoretical ChemistryAmsterdam Institute of Molecular and Life Sciences (AIMMS)Amsterdam Center for Multiscale Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdam (TheNetherlands
Michelle van Dongen Department of Theoretical ChemistryAmsterdam Institute of Molecular and Life Sciences (AIMMS)Amsterdam Center for Multiscale Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdam (TheNetherlands
Israel Fernández Departamento de Química Orgánica I and Centro de Innovación en Química Avanzada (ORFEO-CINQA)Facultad de Ciencias QuímicasUniversidad Complutense de Madrid28040MadridSpain
F. Matthias Bickelhaupt Department of Theoretical ChemistryAmsterdam Institute of Molecular and Life Sciences (AIMMS)Amsterdam Center for Multiscale Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdam (TheNetherlands Institute for Molecules and MaterialsRadboud UniversityHeyendaalseweg 1356525 AJNijmegen (TheNetherlands
Trevor A. Hamlin Department of Theoretical ChemistryAmsterdam Institute of Molecular and Life Sciences (AIMMS)Amsterdam Center for Multiscale Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdam (TheNetherlands

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Bifunctional Hydrogen Bond Donor-Catalyzed Diels-Alder Reactions: Origin of Stereoselectivity and Rate Enhancement

The selectivity and rate enhancement of bifunctional hydrogen bond donor-catalyzed Diels-Alder reactions between cyclopentadiene and acrolein were quantum chemically studied using density functional theory in combination with coupled-cluster theory. (Thio)ureas render the studied Diels-Alder cycloaddition reactions exo selective and induce a significant acceleration of this process by lowering the reaction barrier by up to 7 kcal mol-1 . Our activation strain and Kohn-Sham molecular orbital analyses uncover that these organocatalysts enhance the Diels-Alder reactivity by reducing the Pauli repulsion between the closed-shell filled π-orbitals of the diene and dienophile, by polarizing the π-orbitals away from the reactive center and not by making the orbital interactions between the reactants stronger. In addition, we establish that the unprecedented exo selectivity of the hydrogen bond donor-catalyzed Diels-Alder reactions is directly related to the larger degree of asynchronicity along this reaction pathway, which is manifested in a relief of destabilizing activation strain and Pauli repulsion.

N,N'-Bis[3,5-bis(trifluoromethyl)phenyl]thiourea: a privileged motif for catalyst development

Over the last decade, the use of (thio)urea derivatives as organocatalysts in organic chemistry has increased rapidly. One of the key features is their ability to activate substrates and subsequently stabilize partially developing negative charges (e.g., oxyanions) in the transition states employing explicit double hydrogen bonding. Among (thio)urea-based catalysts, N,N'-bis[3,5-bis(trifluoromethyl)phenyl]thiourea developed by Schreiner's group (abbreviated here as Schreiner's thiourea) has played a very important role in the development of H-bond organocatalysts. Nowadays it is used extensively in promoting organic transformations, and the 3,5-bis(trifluoromethyl)phenyl motif thereof is used ubiquitously in H-bond catalysts. This review summarizes the key developments of Schreiner's thiourea-mediated reactions with the aim to further expand the applications of (thio)urea-based catalysts.