1
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Cioc RC, Harsevoort E, Lutz M, Bruijnincx PCA. Efficient synthesis of fully renewable, furfural-derived building blocks via formal Diels-Alder cycloaddition of atypical addends. GREEN CHEMISTRY : AN INTERNATIONAL JOURNAL AND GREEN CHEMISTRY RESOURCE : GC 2023; 25:9689-9694. [PMID: 38028818 PMCID: PMC10680129 DOI: 10.1039/d3gc02357e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 08/30/2023] [Indexed: 12/01/2023]
Abstract
Diels-Alder (DA) cycloaddition of furanics is emerging as a key transformation in circular chemistry, providing access to highly versatile, biobased platform molecules. Further development of this technology into viable industrial applications faces major challenges, a notorious one being the lack of reactivity of the most readily available furans, i.e. the furfural derivatives. Herein we describe the remarkably-facile intramolecular DA reaction of allyl acetals of different furfurals to efficiently afford formal DA adducts with the atypical, unreactive dienophile allyl alcohol. Our methodology gives access to unprecedented oxanorbornene derivatives in high chemo-, regio- and stereoselectivity, which can be readily diversified into valuable products. This offers the potential of scalable production of renewable chemical building blocks from cheap, bioderived platform molecules.
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Affiliation(s)
- Răzvan C Cioc
- Organic Chemistry and Catalysis, Institute for Sustainable and Circular Chemistry, Faculty of Science, Utrecht University Universiteitsweg 99 3584 CG Utrecht The Netherlands
| | - Eva Harsevoort
- Organic Chemistry and Catalysis, Institute for Sustainable and Circular Chemistry, Faculty of Science, Utrecht University Universiteitsweg 99 3584 CG Utrecht The Netherlands
| | - Martin Lutz
- Dr M. Lutz, Structural Biochemistry, Bijvoet Centre for Biomolecular Research, Faculty of Science, Utrecht University Universiteitsweg 99 3584 CG Utrecht The Netherlands
| | - Pieter C A Bruijnincx
- Organic Chemistry and Catalysis, Institute for Sustainable and Circular Chemistry, Faculty of Science, Utrecht University Universiteitsweg 99 3584 CG Utrecht The Netherlands
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2
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Barløse CL, Faghtmann J, Bitsch RS, Gbubele JD, Jørgensen KA. Asymmetric Organocatalyzed Cascade Reactions─Merging the pseudo-Halogen and Halogen Effect with Dienamine Catalysis. Org Lett 2023; 25:1209-1213. [PMID: 36787642 DOI: 10.1021/acs.orglett.3c00220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
The combination of asymmetric organocatalysis with the (pseudo)-halogen effect enables the formation of chiral norcarane scaffolds in high yields and selectivities (up to 92% yield, >99% ee, and >95:5 d.r.). This was achieved by reacting (pseudo)-halogenated 3-vinyl chromones with in situ generated chiral dienamines in an inverse electron demand [4 + 2] cycloaddition followed by an intramolecular SN2 reaction. These scaffolds could easily undergo photoinduced rearrangements or lactonization to form intricate chiral ring structures.
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Affiliation(s)
| | - Jonas Faghtmann
- Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
| | - René Slot Bitsch
- Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
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3
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Investigating the regio-, stereo-, and enantio-selectivities of the [3 + 2] cycloaddition reaction of C, N-diarylnitrone derivatives with N-propadienylindole derivatives. A DFT Study. COMPUT THEOR CHEM 2023. [DOI: 10.1016/j.comptc.2023.114024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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4
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Wang Z, Yamazaki S, Mikata Y, Oba M, Takashima H, Morimoto T, Ogawa A. Intramolecular Diels-Alder Reactions of α-Bromostyrene-Functionalized Unsaturated Carboxamides. J Org Chem 2022; 87:11148-11164. [PMID: 35944162 DOI: 10.1021/acs.joc.2c01417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Intramolecular cycloaddition reactions of α-bromostyrene-functionalized amides of monomethyl fumarate were investigated. The reaction of the amides with Et3N in toluene at 110 °C gave 1,4-dihydronaphthalenes. The 1,4-dihydronaphthalenes may be produced via the intramolecular Diels-Alder reaction, proton transfer, and dehydrobromination by a base, along with C═C bond isomerization by proton transfer. The reaction of amide derivatives with halogen on a benzene ring and alkali metal carbonates in toluene at 110 °C gave naphthalene derivatives directly. Dehydrogenation of various 1,4-dihydronaphthalenes with cesium or rubidium carbonate in toluene at 110 °C gave naphthalene derivatives. The retardation by TEMPO, acceleration by air for some substrates, and density functional theory calculations suggest a radical mechanism caused by intervention of molecular oxygen.
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Affiliation(s)
- Zhichao Wang
- Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Gakuen-cho 1-1, Nakaku, Sakai, Osaka 599-8531, Japan
| | - Shoko Yamazaki
- Department of Chemistry, Nara University of Education, Takabatake-cho, Nara 630-8528, Japan
| | - Yuji Mikata
- Laboratory for Molecular and Functional Design, Department of Engineering, Nara Women's University Nara 630-8506, Japan
| | - Miho Oba
- Department of Chemistry, Faculty of Science, Nara Women's University, Nara 630-8506, Japan
| | - Hiroshi Takashima
- Department of Chemistry, Faculty of Science, Nara Women's University, Nara 630-8506, Japan
| | - Tsumoru Morimoto
- Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), Takayama, Ikoma, Nara 630-0192, Japan
| | - Akiya Ogawa
- Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Gakuen-cho 1-1, Nakaku, Sakai, Osaka 599-8531, Japan
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5
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Baffour Pipim G, Opoku E. Catalyst-free [3 + 2] cycloaddition reaction of oxa-, aza-, and thio-bicyclic alkenes with cyclic and acyclic nitrones: A mechanistic study. COMPUT THEOR CHEM 2022. [DOI: 10.1016/j.comptc.2022.113790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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6
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Cioc RC, Crockatt M, van der Waal JC, Bruijnincx PCA. The Interplay between Kinetics and Thermodynamics in Furan Diels-Alder Chemistry for Sustainable Chemicals Production. Angew Chem Int Ed Engl 2022; 61:e202114720. [PMID: 35014138 PMCID: PMC9304315 DOI: 10.1002/anie.202114720] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Indexed: 01/21/2023]
Abstract
Biomass‐derived furanic platform molecules have emerged as promising building blocks for renewable chemicals and functional materials. To this aim, the Diels–Alder (DA) cycloaddition stands out as a versatile strategy to convert these renewable resources in highly atom‐efficient ways. Despite nearly a century worth of examples of furan DA chemistry, clear structure–reactivity–stability relationships are still to be established. Detailed understanding of the intricate interplay between kinetics and thermodynamics in these very particular [4+2] cycloadditions is essential to push further development and truly expand the scope beyond the ubiquitous addend combinations of electron‐rich furans and electron‐deficient olefins. Herein, we provide pertinent examples of DA chemistry, taken from various fields, to highlight trends, establish correlations and answer open questions in the field with the aim to support future efforts in the sustainable chemicals and materials production.
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Affiliation(s)
- Răzvan C Cioc
- Organic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | - Marc Crockatt
- Department of Sustainable Process and Energy Systems, TNO, Leeghwaterstraat 44, 2628, CA, Delft, The Netherlands
| | - Jan C van der Waal
- Department of Sustainable Process and Energy Systems, TNO, Leeghwaterstraat 44, 2628, CA, Delft, The Netherlands
| | - Pieter C A Bruijnincx
- Organic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
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7
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Donkor B, Umar AR, Opoku E. Mechanistic elucidation of the tandem Diels–Alder/(3 + 2) cycloadditions in the design and syntheses of heterosteroids. J Mol Model 2022; 28:70. [DOI: 10.1007/s00894-022-05063-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 02/16/2022] [Indexed: 11/28/2022]
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8
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Rashid Umar A, Donkor B, Opoku E. Mechanistic Details of Domino [3+2] Cycloaddition/[3,3] Sigmatropic Shift Reactions of N-Vinyl Nitrones with Isocyanates. COMPUT THEOR CHEM 2022. [DOI: 10.1016/j.comptc.2022.113643] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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9
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Donkor B, Opoku E, Aniagyei A. Theoretical studies on cycloaddition reactions of N-allyl substituted polycyclic Isoindole-1,3-dione with nitrones and nitrile oxides. COMPUT THEOR CHEM 2022. [DOI: 10.1016/j.comptc.2021.113574] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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10
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Cioc R, Crockatt M, Van der Waal JC, Bruijnincx P. The Interplay between Kinetics and Thermodynamics in Furan Diels‐Alder Chemistry for Sustainable Chemicals Production. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202114720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Razvan Cioc
- Utrecht University: Universiteit Utrecht Chemistry NETHERLANDS
| | - Marc Crockatt
- TNO Sustainable Process and Energy Systems NETHERLANDS
| | | | - Pieter Bruijnincx
- Utrecht University Chemistry Universiteitsweg99Netherlands 3584 CG Utrecht NETHERLANDS
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11
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Regio‐, stereo‐, and site‐selectivities of 1,3‐dipolar Cycloaddition reaction of benzonitrile oxide with unsymmetrically substituted norbornenes and norbornadienes: A computational study. J PHYS ORG CHEM 2021. [DOI: 10.1002/poc.4259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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12
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Vargas S, Hennefarth MR, Liu Z, Alexandrova AN. Machine Learning to Predict Diels-Alder Reaction Barriers from the Reactant State Electron Density. J Chem Theory Comput 2021; 17:6203-6213. [PMID: 34478623 DOI: 10.1021/acs.jctc.1c00623] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Reaction barriers are key to our understanding of chemical reactivity and catalysis. Certain reactions are so seminal in chemistry that countless variants, with or without catalysts, have been studied, and their barriers have been computed or measured experimentally. This wealth of data represents a perfect opportunity to leverage machine learning models, which could quickly predict barriers without explicit calculations or measurement. Here, we show that the topological descriptors of the quantum mechanical charge density in the reactant state constitute a set that is both rigorous and continuous and can be used effectively for the prediction of reaction barrier energies to a high degree of accuracy. We demonstrate this on the Diels-Alder reaction, highly important in biology and medicinal chemistry, and as such, studied extensively. This reaction exhibits a range of barriers as large as 270 kJ/mol. While we trained our single-objective supervised (labeled) regression algorithms on simpler Diels-Alder reactions in solution, they predict reaction barriers also in significantly more complicated contexts, such a Diels-Alder reaction catalyzed by an artificial enzyme and its evolved variants, in agreement with experimental changes in kcat. We expect this tool to apply broadly to a variety of reactions in solution or in the presence of a catalyst, for screening and circumventing heavily involved computations or experiments.
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Affiliation(s)
- Santiago Vargas
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095-1569, United States
| | - Matthew R Hennefarth
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095-1569, United States
| | - Zhihao Liu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095-1569, United States
| | - Anastassia N Alexandrova
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095-1569, United States.,California NanoSystems Institute, University of California, Los Angeles, 570 Westwood Plaza, Los Angeles, California 90095-1569, United States
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13
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Samba WK, Amoah A, Tia R, Adei E. Theoretical investigation of the regio-, enantio-, and stereo-selectivities of the (3 + 2) cycloaddition reactions of N-vinylindoles with nitrones and nitrile oxides. Theor Chem Acc 2021. [DOI: 10.1007/s00214-021-02847-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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14
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Does the reaction of nitrone derivatives with allenoates proceed by an initial (3 + 2) cycloaddition or O-Nucleophilic addition? A quantum chemical investigation. J Mol Graph Model 2021; 109:108036. [PMID: 34614454 DOI: 10.1016/j.jmgm.2021.108036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 08/29/2021] [Accepted: 09/19/2021] [Indexed: 11/24/2022]
Abstract
The question of whether the reaction between nitrone derivatives and allenoates proceeds with initial (3 + 2) cycloaddition (32CA) or the oxygen-nucleophilic (O-nucleophilic) addition has been theoretically investigated using density functional theory (DFT) at the M06-2X/6-311G(d,p) level of theory. In all of the reactions considered, the initial 32CA route is kinetically and thermodynamically preferred over the initial O-nucleophilic addition. Increasing the steric bulk of the substituents on the reactants bridges the kinetic and thermodynamic gap between the initial 32CA and O-nucleophilic addition but the 32CA is still energetically preferred, showing that with increasing steric bulk, the O-nucleophilic addition may become competitive with the 32CA route. Within the 32CA reactions, analysis of electrophilic (Pk+) and nucleophilic (Pk-) Parr functions at the various reaction centers in the allenoate indicates that the three-atom-components (TACs) chemo-selectively add across the olefinic bond bearing the ester functionality (COOMe) with the largest Mulliken spin density coefficients and this observation agrees with the energetic trends and experimental outcomes. The global electron density transfer (GEDT) analysis reveals a high polar character associated with the 32CA reaction of methylbuta-2,3-dienoate with N-methyl-C-phenylnitrone while that of the 32CA reaction of methylpenta-2,3-dienoate with N-cyclohexenylnitrone has a low polar character.
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15
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A DFT study of the double (3 + 2) cycloaddition of nitrile oxides and allenoates for the formation of spirobiisoxazolines. J Mol Graph Model 2021; 109:108033. [PMID: 34534890 DOI: 10.1016/j.jmgm.2021.108033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/25/2021] [Accepted: 09/05/2021] [Indexed: 11/20/2022]
Abstract
The molecular mechanism of the double (3 + 2) cycloaddition (32CA) reaction between nitrile oxides and allenoates has been studied using density functional theory at the M06-2X/6-311G (d,p) level of theory. In the first 32CA, the nitrile oxide adds chemo- and regio-selectively to the C-C double bond of the allenoate closest to the carboxylate group followed by a subsequent regioselective addition to the olefinic bond of the isoxazoline intermediate. The rate constant for the preferred pathway (formation of 4-methylene-2-isoxazoline intermediate) in the reaction of ethyl substituted allenoate and mesitonitrile oxide is 5.3 × 102 s-1 in THF which is about 13 times faster than the closest competing step (formation of its regioisomer 5-methylene-2-isoxazoline intermediate) which has a rate constant of 4.4 × 101 s-1. Strong electron-donating groups (EDGs) and electron-withdrawing groups (EWGs) decrease activation barriers and hence increase the reaction rate. Also, the dimerization of nitrile oxide to form furaxon is found to be kinetically unfavored.
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16
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Tawiah A, Pipim GB, Tia R, Adei E. Exploring the chemo-, regio-, and stereoselectivities of the (3 + 2) cycloaddition reaction of 5,5-dimethyl-3-methylene-2-pyrrolidinone with C,N-diarylnitrones and nitrile oxide derivatives: a DFT study. J Mol Model 2021; 27:287. [PMID: 34532750 DOI: 10.1007/s00894-021-04911-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 09/08/2021] [Indexed: 11/29/2022]
Abstract
The (3 + 2) cycloaddition (32CA) reaction is an efficient method for the synthesis of many biologically active heterocyclic compounds, but there are several regio- and stereochemical issues that must be fully understood to exploit the full utility of its synthetic power. We herein explored the chemo-, regio-, and stereoselectivities of the 32CA reaction of 5,5-dimethyl-3-methylene-2-pyrrolidinone (B1) to C,N-diarylnitrones (B2), and nitrile oxide derivatives (B3) with DFT at the M06/6-311G(d,p) level of theory. The reactions occur via an asynchronous one-step mechanism, with the chemoselective addition of the C,N-diarylnitrones, and nitrile oxide derivatives across the olefinic bond of 5,5-dimethyl-3-methylene-2-pyrrolidinone being the most preferred kinetically and thermodynamically. The regio- and stereoselectivities of the reactions are affected by the electronic and steric nature of substituents on B2 but they are not affected by the electronic and steric nature of substituents on B3. The C,N-nitrones and the nitrile oxide derivatives add across the atomic centers with the largest atomic spin densities on 5,5-dimethyl-3-methylene-2-pyrrolidinone as seen through the local electrophilic ([Formula: see text]) and nucleophilic ([Formula: see text]) Parr functions of the various reaction centers. Results from the global electron density transfer (GEDT) reveal the low polar nature of the reactions.
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Affiliation(s)
- Anthony Tawiah
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - George Baffour Pipim
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Richard Tia
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Evans Adei
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
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17
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Atta-Kumi J, Pipim GB, Tia R, Adei E. Investigating the site-, regio-, and stereo-selectivities of the reactions between organic azide and 7-heteronorbornadiene: a DFT mechanistic study. J Mol Model 2021; 27:248. [PMID: 34387742 DOI: 10.1007/s00894-021-04857-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 07/28/2021] [Indexed: 11/25/2022]
Abstract
The site-, regio-, and stereo-selectivities of the title reactions have been studied using density functional theory (DFT) at the M06/6-311G(d,p) level of theory. The effects of substituents on both the three-atom component (TAC) and norbornadiene derivatives have been investigated with a focus on the site-selectivity. The reaction of benzylazide with (1S,4R)-2-tosyl-7-oxabicyclo[2.2.1]hepta-2,5-diene and (1R,4S)-2-bromo-3-tosyl-7-oxabicyclo[2.2.1]hepta-2,5-diene proceeds via addition across the substituted olefinic bond of the two norbornadiene derivatives. Substituents on the TAC do not affect the selectivity of the reaction while substituents on the norbornadiene significantly affect the selectivity of the reaction. Benzylazide preferentially adds across the substituted olefinic bond of the norbornadiene derivative when strong electron-withdrawing group (EWGs) and electron-releasing group (ERGs) substituents are on the norbornadiene while weak ERGs and EWGs on the norbornadiene significantly decreases the site-selectivity such that addition across either double is no longer favored over the other. The formation of exo-cycloadducts is generally favored over the endo-cycloadducts. The reaction of benzylazide and norbornadiene derivatives is a highly irreversible exergonic reaction. The direction of electron density flux is dependent on the nature of the substituent on the reactants. Global reactivity indices and Parr function calculations are in good agreement with the activation barriers and the selectivity of the reactions.
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Affiliation(s)
- Joshua Atta-Kumi
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - George Baffour Pipim
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Richard Tia
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Evans Adei
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
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18
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Barløse CL, Østergaard NL, Bitsch RS, Iversen MV, Jørgensen KA. A Direct Organocatalytic Enantioselective Route to Functionalized
trans
‐Diels–Alder Products Having the Norcarane Scaffold. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202106598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Casper L. Barløse
- Department of Chemistry Aarhus University Langelandsgade 140 8000 Aarhus C Denmark
| | - Niklas L. Østergaard
- Department of Chemistry Aarhus University Langelandsgade 140 8000 Aarhus C Denmark
| | - René S. Bitsch
- Department of Chemistry Aarhus University Langelandsgade 140 8000 Aarhus C Denmark
| | - Marc V. Iversen
- Department of Chemistry Aarhus University Langelandsgade 140 8000 Aarhus C Denmark
| | - Karl Anker Jørgensen
- Department of Chemistry Aarhus University Langelandsgade 140 8000 Aarhus C Denmark
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19
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Barløse CL, Østergaard NL, Bitsch RS, Iversen MV, Jørgensen KA. A Direct Organocatalytic Enantioselective Route to Functionalized trans-Diels-Alder Products Having the Norcarane Scaffold. Angew Chem Int Ed Engl 2021; 60:18318-18327. [PMID: 34080269 DOI: 10.1002/anie.202106598] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/02/2021] [Indexed: 11/07/2022]
Abstract
An enantioselective methodology to construct trans-Diels-Alder scaffolds by organocatalysis with excellent selectivity, high yield and up to five contiguous stereocenters is presented. The reaction concept integrates the halogen effect and a novel discovered pseudo-halogen effect to direct an endo-selective, secondary-amine catalyzed Diels-Alder reaction allowing for the subsequent formation of trans-Diels-Alder cycloadducts featuring the norcarene scaffold. The methodology relies on the reaction between an in situ generated trienamine and an α-brominated or α-pseudo-halogenated enone to form a fleeting cis-Diels-Alder intermediate. The endo-transition state-enhanced by the (pseudo-)halogen effect-sets the stereochemistry that allows for a subsequent SN 2-like reaction at a tertiary center to obtain the trans-Diels-Alder scaffold. The mechanism was investigated and supported by experimental results as well as computational studies.
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Affiliation(s)
- Casper L Barløse
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Niklas L Østergaard
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - René S Bitsch
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Marc V Iversen
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Karl Anker Jørgensen
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
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20
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Pipim GB, Tia R, Adei E. Quantum chemical investigation of the formation of spiroheterocyclic compounds via the (3 + 2) cycloaddition reaction of 1-methyl-3-(2,2,2-trifluoroethylidene) pyrrolidin-2-one with diazomethane and nitrone derivatives. Tetrahedron 2021. [DOI: 10.1016/j.tet.2021.132306] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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21
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Deb T, Tu J, Franzini RM. Mechanisms and Substituent Effects of Metal-Free Bioorthogonal Reactions. Chem Rev 2021; 121:6850-6914. [DOI: 10.1021/acs.chemrev.0c01013] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Titas Deb
- Department of Medicinal Chemistry, University of Utah, 30 S 2000 E, Salt Lake City, Utah 84112, United States
| | - Julian Tu
- Department of Medicinal Chemistry, University of Utah, 30 S 2000 E, Salt Lake City, Utah 84112, United States
| | - Raphael M. Franzini
- Department of Medicinal Chemistry, University of Utah, 30 S 2000 E, Salt Lake City, Utah 84112, United States
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Costa FLP, de Albuquerque ACF, Fiorot RG, Lião LM, Martorano LH, Mota GVS, Valverde AL, Carneiro JWM, dos Santos Junior FM. Structural characterisation of natural products by means of quantum chemical calculations of NMR parameters: new insights. Org Chem Front 2021. [DOI: 10.1039/d1qo00034a] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In this review, we focus in all aspects of NMR simulation of natural products, from the fundamentals to the new computational toolboxes available, combining advanced quantum chemical calculations with upstream data processing and machine learning.
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Affiliation(s)
| | - Ana C. F. de Albuquerque
- Departamento de Química Orgânica
- Instituto de Química
- Universidade Federal Fluminense
- Niterói-RJ
- Brazil
| | - Rodolfo G. Fiorot
- Departamento de Química Orgânica
- Instituto de Química
- Universidade Federal Fluminense
- Niterói-RJ
- Brazil
| | - Luciano M. Lião
- Instituto de Química
- Universidade Federal de Goiás
- 74690-900 Goiânia-GO
- Brazil
| | - Lucas H. Martorano
- Departamento de Química Orgânica
- Instituto de Química
- Universidade Federal Fluminense
- Niterói-RJ
- Brazil
| | - Gunar V. S. Mota
- Faculdade de Ciências Naturais/Instituto de Ciências Exatas e Naturais
- Universidade Federal do Pará
- Belém-PA
- Brazil
| | - Alessandra L. Valverde
- Departamento de Química Orgânica
- Instituto de Química
- Universidade Federal Fluminense
- Niterói-RJ
- Brazil
| | - José W. M. Carneiro
- Departamento de Química Inorgânica
- Instituto de Química
- Universidade Federal Fluminense
- Niterói-RJ
- Brazil
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23
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Umar AR, Tia R, Adei E. The 1,3-dipolar cycloaddition of adamantine-derived nitrones with maleimides: A computational study. COMPUT THEOR CHEM 2021. [DOI: 10.1016/j.comptc.2020.113099] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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24
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Quijano-Quiñones RF, Guadarrama-Moreno J, Quesadas-Rojas M, Mena-Rejón GJ, Castro-Segura CS, Cáceres-Castillo D. The origin of the regiospecificity of acrolein dimerization. RSC Adv 2021; 11:7459-7465. [PMID: 35423251 PMCID: PMC8695078 DOI: 10.1039/d0ra10084f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/07/2021] [Indexed: 11/21/2022] Open
Abstract
The NCI at the transition state are the key factor controlling the regiospecificity in the acrolein dimerization.
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Affiliation(s)
| | | | - Mariana Quesadas-Rojas
- Posgrado en Ciencias del Mar y Limnología
- UNAM
- Mexico
- Escuela Nacional de Educación Superior
- UNAM
| | - Gonzalo J. Mena-Rejón
- Laboratorio de Química Farmaceútica
- Facultad de Química
- Universidad Autónoma de Yucatán
- Mérida
- Mexico
| | | | - David Cáceres-Castillo
- Laboratorio de Química Farmaceútica
- Facultad de Química
- Universidad Autónoma de Yucatán
- Mérida
- Mexico
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25
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Baffour Pipim G, Tia R, Adei E. Computational exploration of the 1,3‐dipolar cycloaddition reaction of 7‐isopropylidenebenzonorbornadiene with nitrile oxide and cyclic nitrone derivatives. J PHYS ORG CHEM 2020. [DOI: 10.1002/poc.4174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- George Baffour Pipim
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry Kwame Nkrumah University of Science and Technology Kumasi Ghana
| | - Richard Tia
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry Kwame Nkrumah University of Science and Technology Kumasi Ghana
| | - Evans Adei
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry Kwame Nkrumah University of Science and Technology Kumasi Ghana
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26
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Pipim GB, Tia R, Adei E. (3 + 2) cycloaddition reaction of 7-isopropylidenebenzonorbornadiene and diazomethane derivatives: A theoretical study. J Mol Graph Model 2020; 101:107713. [PMID: 32882633 DOI: 10.1016/j.jmgm.2020.107713] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/30/2020] [Accepted: 07/31/2020] [Indexed: 02/07/2023]
Abstract
The ability to synthesize targeted molecules hinges on detailed mechanistic insight of the reaction. The 1,3-dipolar cycloaddition reaction between diazomethane derivatives and 7-isopropylidenebenzonorbornadiene have been extensively studied using density functional theory (DFT) at the M06-2X/6-311G(d,p) level of theory in order to delineate the peri-, regio-, and stereo-selectivities of the reaction. The diazomethane is shown to periselectively add across the endocyclic olefinic bond of the 7-isopropylidenebenzonorbornadiene and stereoselectively in the exo fashion, yielding the exo-cycloadduct as the major product, with a rate constant of 3.83 × 104 s-1. The endo approach of this periselective path is the closest competing pathway with a rate constant of 8.78 × 101 s-1. Neither electron-donating groups (R = methyl, ethyl, amine, cyclopropyl) nor electron-withdrawing groups (R = cyano, nitro, carbonyl) on the diazomethane alters the peri- and stereo-selectivity of the reaction. However, the substituents do have an effect on whether the addition follow normal or inverse electron demand mechanisms. EDGs favor a normal electron demand mechanism while EWGs favor an inverse electron demand 1,3-dipolar cycloaddition reaction. While EDGs-substituted diazomethane derivatives behave as nucleophiles in reactions with 7-isopropylidenebenzonorbornadiene, EWGs-substituted diazomethane derivatives behave as electrophiles. The 1,3-dipole adds across the dipolarophile via a concerted asynchronous mechanism, but a stepwise diradical mechanism has been ruled out. The selectivities observed in the title reaction are kinetically controlled. Analysis of the nucleophilic Parr function (PK-) at the different reaction sites in the dipolarophile indicates that the diazomethane adds across the atomic centers with highest NBO and Mulliken atomic spin densities.
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Affiliation(s)
- George Baffour Pipim
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Richard Tia
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Evans Adei
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
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27
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Pipim GB, Tia R, Adei E. Investigating the regio-, stereo-, and enantio-selectivities of the 1,3-dipolar cycloaddition reaction of C-cyclopropyl-N-phenylnitrone derivatives and benzylidenecyclopropane derivatives: A DFT study. J Mol Graph Model 2020; 100:107672. [PMID: 32659628 DOI: 10.1016/j.jmgm.2020.107672] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 06/23/2020] [Accepted: 06/24/2020] [Indexed: 01/03/2023]
Abstract
The biomedical importance of spirocyclopropane isoxazolidine derivatives is widely known. The 1,3-dipolar cycloaddition (1,3-DC) of C-cyclopropyl-N-phenylnitrone derivative and benzylidenecyclopropane derivatives leading to the formation of 5- and 4-spirocyclopropane isoxazolidines derivatives have been studied using density functional theory (DFT) at M06-2X/6-311G (d,p) level of theory. An extensive exploration of the potential energy surface shows that the 1,3-dipole adds across the dipolarophile via an asynchronous concerted mechanism. While electron-donating groups (EDGs) on the benzylidenecyclopropane favor the formation of the 4-spirocyclopropane isomer, electron-withdrawing groups (EWGs) favor the reaction channels that furnish the 5-spirocyclopropane isoxazolidine isomer. Both EWDs and EDGs on the 1,3-dipole favor the formation of the 5-spirocyclopropane isoxazolidine isomer. Irrespective of the electronic nature of substituents on the C-cyclopropyl-N-phenylnitrone, the reaction channels that regioselectively lead to the formation of the 5-spirocyclopropane isoxazolidine isomer are favored. In all reactions considered, the channels that selectively lead to the formation of the cis-diastereoisomers proceed with lower activation barriers than the trans-diastereoisomers. In all cases, the observed selectivities in the title reaction are kinetically controlled.
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Affiliation(s)
- George Baffour Pipim
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Richard Tia
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Evans Adei
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
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28
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Opoku E, Baffour Pipim G, Tia R, Adei E. Mechanistic study of the tandem intramolecular (4 + 2)/intermolecular (3 + 2) cycloaddition reactions for the formation of polyaza‐ and polyisoxazolidine‐steroids. J Heterocycl Chem 2020. [DOI: 10.1002/jhet.3900] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Ernest Opoku
- Theoretical and Computational Chemistry Laboratory, Department of ChemistryKwame Nkrumah University of Science and Technology Kumasi Ghana
| | - George Baffour Pipim
- Theoretical and Computational Chemistry Laboratory, Department of ChemistryKwame Nkrumah University of Science and Technology Kumasi Ghana
| | - Richard Tia
- Theoretical and Computational Chemistry Laboratory, Department of ChemistryKwame Nkrumah University of Science and Technology Kumasi Ghana
| | - Evans Adei
- Theoretical and Computational Chemistry Laboratory, Department of ChemistryKwame Nkrumah University of Science and Technology Kumasi Ghana
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29
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DFT mechanistic studies on the regio-, stereo-, and enantio-selectivity of 1,3 dipolar cycloadditions of quinolinium imides with olefins, maleimides, and benzynes for the synthesis of fused N,N'-heterocycles. J Mol Model 2020; 26:36. [PMID: 31989273 DOI: 10.1007/s00894-020-4299-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 01/14/2020] [Indexed: 10/25/2022]
Abstract
This work investigated computationally the regio-, stereo-, and enantio-selectivity of the reactions of azomethine imines with olefins, maleimides, and benzynes, important reactions towards the synthesis of heteropolycyclic, N,N'-fused, spirocyclic systems, which serve as building blocks for the synthesis of many pharmaceuticals, agrochemicals, and biologically active compounds. The results show that the thermally controlled diastereoselective [3 + 2] cycloaddition reaction between quinolinium imide and methyl acrylate provides two regio-isomers: 1,4-regioisomer (N-C1, C-C2) and 1,3-regioisomer (N-C2, C-C1). The 1,4-regioisomer has cis and trans-stereoisomers while the 1,3-regioisomer has R-enantiomer and S-enantiomer, and the barriers for the formation of these isomers are 5.1, 19.1, 10.7, and 10.5 kcal/mol, respectively. The reaction between quinolinium imide and maleimide leads to the formation of two stereoisomers; cis-isomer and trans-isomer in which the cis-isomer is kinetically and thermodynamically favoured by 6.1 kcal/mol and 8.7 kcal/mol, respectively. The reaction between quinolinium imide and benzyne also leads to the formation of two stereoisomers through one transition state, with a barrier of 3.0 kcal/mol. Global electrophilicity index calculations show that the dipole acts as a good electrophile in the reaction and decreasing or increasing electrophilicity index has no correlation with the activation barriers. Graphical abstractPathways of the 1,3 dipolar cycloadditions of quinolinium imides with olefins, maleimides, and benzynes for the synthesis of fused N,N'-heterocycles.
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30
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Pipim GB, Opoku E, Tia R, Adei E. Peri-, Chemo-, Regio-, Stereo- and Enantio-Selectivities of 1,3-dipolar cycloaddition reaction of C,N-Disubstituted nitrones with disubstituted 4-methylene-1,3-oxazol-5(4H)- one: A quantum mechanical study. J Mol Graph Model 2020; 97:107542. [PMID: 32004806 DOI: 10.1016/j.jmgm.2020.107542] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 01/15/2020] [Accepted: 01/16/2020] [Indexed: 10/25/2022]
Abstract
The peri-, chemo-, regio-, stereo- and enantio-selectivities of 1,3-dipolar cycloaddition reaction of C,N-disubstituted nitrones with disubstituted 4-methylene-1,3-oxazol-5(4H)-one have been studied using density functional theory (DFT) at the M06-2X/6-311G (d,p) level of theory. The 1,3-dipole preferentially adds chemo-selectively across the olefinic bond in a (3 + 2) fashion forming the corresponding spirocycloadduct. The titled reaction occurs with poor enantio- and stereo-selectivities, but a high degree of regio-selectivity is observed for the addition of the 1,3-dipole across the dipolarophile. Electron-withdrawing groups on the dipolarophile significantly reduce the activation barriers while electron-donating groups on the dipolarophile increase the activation barriers. Analysis of the HOMO and LUMO energies of the two reacting species indicates that the 1,3-dipole reacts as a nucleophile while the dipolarophile reacts as the electrophile. Investigation of the electrophilic Parr function (PK+) at the various reaction centers in the dipolarophile indicates that the 1,3-dipole selectively adds across the atomic species with the largest electrophilic Mulliken and NBO atomic spin densities which is in accordance with the energetic trends observed.
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Affiliation(s)
- George Baffour Pipim
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Ernest Opoku
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Richard Tia
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Evans Adei
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
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31
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Site-, enantio- and stereo-selectivities of the 1,3-dipolar cycloaddition reactions of oxanorbornadiene with C,N-disubstituted nitrones and dimethyl nitrilimines: a DFT mechanistic study. Theor Chem Acc 2020. [DOI: 10.1007/s00214-019-2529-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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32
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Liu ZY, Zhang M, Wang XC. Hydrosilylation-Promoted Furan Diels-Alder Cycloadditions with Stereoselectivity Controlled by the Silyl Group. J Am Chem Soc 2019; 142:581-588. [PMID: 31809027 DOI: 10.1021/jacs.9b11909] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Herein we describe an unprecedented B(C6F5)3-catalyzed cascade reaction of N-allyl-N-furfurylamides involving an initial intramolecular furan Diels-Alder reaction and subsequent ether cleavage. The reaction has a broad substrate scope, even tolerating a trialkyl-substituted olefin as the dienophile, which has not previously been observed with conventional furan Diels-Alder reactions. In addition, the relative configuration of the product can be controlled by the choice of the silyl group: reactions involving Et3SiH and iPr3SiH gave different diastereomers. Control experiments and the computational studies revealed that the steric bulk of the silyl group plays a key role in determining the reaction pathway and thus the relative configuration of the product.
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Affiliation(s)
- Zhi-Yun Liu
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry , Nankai University , Tianjin 300071 , China
| | - Ming Zhang
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry , Nankai University , Tianjin 300071 , China
| | - Xiao-Chen Wang
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry , Nankai University , Tianjin 300071 , China
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33
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Roland D, Haleegoah JN, Opoku E, Tia R, Adei E. Mechanistic studies on tandem cascade [4 + 2]/ [3 + 2] cycloaddition of 1,3,4-oxadiazoles with olefins. J Mol Graph Model 2019; 93:107452. [PMID: 31541992 DOI: 10.1016/j.jmgm.2019.107452] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/10/2019] [Accepted: 09/11/2019] [Indexed: 10/26/2022]
Abstract
The mechanism of the reaction of 1,3,4-oxadiazoles with alkenes (ethylene) and cycloalkenes (cyclobutene, cyclopentene, cyclohexene and cycloocene) have been studied computationally at the DFT M06-2X/6-311G* level. The reaction is found to proceed via a concerted [4 + 2] addition followed by nitrogen extrusion and then [3 + 2] addition in a tandem cascade fashion, which in the case of cycloalkenes leads to exo-fused or endo-fused subframes, the exo of which is kinetically and thermodynamically favored. The [4 + 2] step is the rate-determining step of the reaction. CF3 as a substituent on the 1,3,4-oxadiazole decreases the activation barriers of the rate-determining step, while CO2Me on the oxadiazole increases the activation barriers of the rate-determining step, markedly in the case of the reaction with cyclopentene and only marginally in the reactions with ethylene. Increasing temperature decreases the barrier of the rate-determining step and stability of the products but increases the rate of the nitrogen extrusion step. The low barriers of the second and third steps of the reaction compared to the first step means that the intermediates will not be isolated in the reaction, confirming the experimental observations of earlier workers. Based on calculated activation barriers, the reactivity of the various cycloalkenes considered in this study follows the order: cyclooctene > cyclopentene > cyclohexene > cyclobutene which is consistent with the trends in product yields obtained in earlier experimental studies.
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Affiliation(s)
- Daniel Roland
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Jamin Nathaniel Haleegoah
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Ernest Opoku
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Richard Tia
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Evans Adei
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
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1, 3-Dipolar cycloaddition reactions of selected 1,3-dipoles with 7-isopropylidenenorbornadiene and follow-up thermolytic cleavage: A computational study. J Mol Graph Model 2019; 92:267-279. [PMID: 31425904 DOI: 10.1016/j.jmgm.2019.08.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 08/02/2019] [Accepted: 08/06/2019] [Indexed: 11/22/2022]
Abstract
The mechanism, regio-, stereo-, and enantio-selectivities of the 1,3-dipolar cycloaddition reactions of 7-isopropylidenenorbornadiene (DENBD) with nitrones and azides to form pharmaceutically relevant isoxazolidine and triazole analogues have been studied computationally at the M06/6-31G(d), 6-31G(d,p), 6-311G(d,p), 6-311++G(d,p) and M06-2X/6-31G(d) levels of theory. In the reactions of DENBD with phenyl nitrones, the cycloaddition steps have low activation barriers, with the highest being 16 kcal/mol; and the Diels-Alder cycloreversion steps have generally high barriers, with the lowest being 20 kcal/mol, suggesting that the isolable products in these reactions are the bicyclic isoxazolidine cycloadducts and not the thermolytic products. This is in contrast to the reactions of DENBD with phenyl azide where the isolable products are predicted to be the thermolytic products since the Diels-Alder cycloreversion steps had relatively lower activation barriers. Electron-donating substituents on the dipolarophile substrate favour attack of the nitrone on the least hindered side of the DENBD substrate while electron-withdrawing substituents on the dipolarophile substrate favour attack on the more hindered side of the DENBD, indicating that site-selectivity is affected by nature of substituents. Global reactivity indices calculations are in good agreement with the activation barriers obtained. Analysis of the electrophilic (PK+) and nucleophilic (PK-) Parr functions at the reactive centres reveal that the cycloaddition occurs between atoms with the largest Mulliken and NBO atomic spin densities which agrees well with the energetic trends and the experimental product outcomes.
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Quantum chemical studies on the mechanistic aspects of tandem sequential cycloaddition reactions of cyclooctatetraene with ester and nitrones. J Mol Graph Model 2019; 92:17-31. [PMID: 31302500 DOI: 10.1016/j.jmgm.2019.06.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 06/26/2019] [Accepted: 06/27/2019] [Indexed: 11/20/2022]
Abstract
The mechanisms of the tandem sequential [4 + 2]/[3 + 2] and [3 + 2]/[4 + 2] cycloaddition sequences involving an ester, cyclooctatetraene (COTE), and cyclic and acyclic nitrones for the formation of a diverse range of isoxazolidine derivatives and other synthetic precursors are reported. A thorough exploration of the PES has characterized several regio-, stereo- and enantio-selective mechanistic channels involved in these reactions. A perturbation molecular orbital (PMO) analysis been employed to rationalize the results. It has also been found that the initial electrocyclic ring closure of the COTE is the rate-determining step in the tandem sequential [4 + 2]/[3 + 2] addition sequence. The thermolytic breakdown of the tandem adducts to subsequent monocyclic, bicyclic and tricyclic adducts occurs generally with very high activation barriers making it an inconvenient synthetic approach. The different reactivity of all the three double bonds present in the dipolarophile is reported. Finally, the mechanistic possibilities of [3 + 2]/[4 + 2] addition sequences involving the same reaction components in the case of cyclic and acyclic nitrones are explored extensively. The results suggest a novel and convenient routes for obtaining products of high selectivity with less energetic requirements. In some instances, new cycloadducts hitherto unreported are obtained.
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36
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Opoku E, Tia R, Adei E. DFT mechanistic study on tandem sequential [4 + 2]/[3 + 2] addition reaction of cyclooctatetraene with functionalized acetylenes and nitrile imines. J PHYS ORG CHEM 2019. [DOI: 10.1002/poc.3992] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ernest Opoku
- Theoretical and Computational Chemistry Laboratory, Department of ChemistryKwame Nkrumah University of Science and Technology Kumasi Ghana
| | - Richard Tia
- Theoretical and Computational Chemistry Laboratory, Department of ChemistryKwame Nkrumah University of Science and Technology Kumasi Ghana
| | - Evans Adei
- Theoretical and Computational Chemistry Laboratory, Department of ChemistryKwame Nkrumah University of Science and Technology Kumasi Ghana
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Computational studies on [4 + 2] / [3 + 2] tandem sequential cycloaddition reactions of functionalized acetylenes with cyclopentadiene and diazoalkane for the formation of norbornene pyrazolines. J Mol Model 2019; 25:168. [PMID: 31119394 DOI: 10.1007/s00894-019-4056-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 04/29/2019] [Indexed: 10/26/2022]
Abstract
The mechanistic pathways for the sequential tandem [4 + 2] / [3 + 2] versus [3 + 2] / [4 + 2] cycloaddition reaction of functionalized acetylenes with cyclopentadiene and dimethyl diazopropane for the formation of norbornene pyrazolines, employed in the synthesis of pharmaceutically relevant compounds, have been studied computationally with DFT at the M06-2X/6-31G(d) and M06-2X/6-31G(d,p) levels of theory. We have established that, in the reaction of the parent (unsubstituted) acetylene with cyclopentadiene and dimethyl diazopropane, the order of the tandem addition has no substantial effects in product outcomes. The same product is obtained provided the reaction components remain the same for both [4 + 2]/[3 + 2] and [3 + 2]/[4 + 2] tandem addition sequences. The results indicate that the [4 + 2] Diels-Alder addition step is the rate-determining step irrespective of the addition order, while the 1,3-dipolar cycloaddition step has been found to generally proceed rapidly with very low activation energies. It has also been realized that the regio-, stereo-, and chemo-selectivities of the reaction are strictly dictated by the type of substituent on the parent acetylene. For substituted acetylenes, we conclude that the sequence of the tandem addition generally affects the type of isomeric product obtained. The [4 + 2]/[3 + 2] tandem addition sequence has been established to favor the exo stereo-selective isomer over the endo, whereas the [3 + 2]/[4 + 2] tandem addition sequence generally favors the endo product formation. Therefore, it is settled that the mechanistic route taken by any substrate in the [4 + 2]/[3 + 2] versus [3 + 2]/[4 + 2] sequential tandem cycloaddition is greatly affected by both electronic and steric factors. Electrophilicity indices calculations agree with the activation barriers obtained. Perturbation molecular orbital theory was employed to rationalize the results. Global reactivity indices calculations gave a good correlation with the activation energies. Graphical abstract The sequential tandem [4 + 2] / [3 + 2] versus [3 + 2] / [4 + 2] cycloaddition reaction of functionalized acetylenes with cyclopentadiene and dimethyl diazopropane for the formation of norbornene pyrazolines.
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Ren D, Xu L, Wang L, Li SS. Catalytic Formal Benzylic C–H Bond Functionalization of 2,5-Dialkylfuran Derivatives with Ferrocenyl Alcohols as Alkylation Reagents. Org Lett 2019; 21:627-631. [DOI: 10.1021/acs.orglett.8b03701] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Didi Ren
- College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, Qingdao 266109, China
| | - Lubin Xu
- College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, Qingdao 266109, China
| | - Liang Wang
- College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, Qingdao 266109, China
| | - Shuai-Shuai Li
- College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, Qingdao 266109, China
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39
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Sugiura H, Yamazaki S, Go K, Ogawa A. Intramolecular Cyclization of 3,3-Diarylpropenylamides of Electron-Deficient Alkenes: Stereoselective Synthesis of Functionalized Hexahydrobenzo[ f
]isoindoles. European J Org Chem 2019. [DOI: 10.1002/ejoc.201801508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Hirotaka Sugiura
- Department of Applied Chemistry; Graduate School of Engineering; Osaka Prefecture University; Gakuen-cho 1-1 599-8531 Nakaku, Sakai Osaka Japan
| | - Shoko Yamazaki
- Department of Chemistry; Nara University of Education; Takabatake-cho 630-8528 Nara Japan
| | - Kakeru Go
- Department of Chemistry; Nara University of Education; Takabatake-cho 630-8528 Nara Japan
| | - Akiya Ogawa
- Department of Applied Chemistry; Graduate School of Engineering; Osaka Prefecture University; Gakuen-cho 1-1 599-8531 Nakaku, Sakai Osaka Japan
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40
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Tao H, Liu F, Zeng R, Shao Z, Zou L, Cao Y, Murphy JM, Houk KN, Liang Y. Origins of halogen effects in bioorthogonal sydnone cycloadditions. Chem Commun (Camb) 2018; 54:5082-5085. [PMID: 29707720 PMCID: PMC5953849 DOI: 10.1039/c8cc02128g] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Halogen substituents increase sydnone cycloaddition reactivities substantially. Fluoro-sydnones are superior to bromo- and chloro-sydnones, and can achieve extremely high second-order rate constants with strained alkynes. Computational studies have revealed the fluorine substituent increases the reactivity of sydnone mainly by lowering its distortion energy.
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Affiliation(s)
- Huimin Tao
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
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41
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Levandowski BJ, Hamlin TA, Helgeson RC, Bickelhaupt FM, Houk KN. Origins of the Endo and Exo Selectivities in Cyclopropenone, Iminocyclopropene, and Triafulvene Diels-Alder Cycloadditions. J Org Chem 2018; 83:3164-3170. [PMID: 29470085 PMCID: PMC6314817 DOI: 10.1021/acs.joc.8b00025] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The endo and exo stereoselectivities of Diels-Alder reactions of cyclopropenone, iminocyclopropene, and substituted triafulvenes with butadiene were rationalized using density functional theory calculations. When cyclopropenone is the dienophile, there is a 1.8 kcal/mol preference for the exo cycloaddition with butadiene, while the reaction of 3-difluoromethylene triafulvene with butadiene favors the endo cycloaddition by 2.8 kcal/mol. The influence of charge transfer and secondary orbital interactions on the stereoselectivity of Diels-Alder reactions involving triafulvenes and heteroanalogs is discussed. The predicted stereoselectivity correlates with both the charge and highest occupied molecular orbital (HOMO) coefficient at the C3 carbon of the triafulvene motif.
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Affiliation(s)
- Brian J Levandowski
- Department of Chemistry and Biochemistry , University of California , Los Angeles , California 90095 , United States
| | - Trevor A Hamlin
- Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling (ACMM) , Vrije Universiteit Amsterdam , 1081 HV Amsterdam , The Netherlands
| | - Roger C Helgeson
- Department of Chemistry and Biochemistry , University of California , Los Angeles , California 90095 , United States
| | - F Matthias Bickelhaupt
- Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling (ACMM) , Vrije Universiteit Amsterdam , 1081 HV Amsterdam , The Netherlands
- Institute for Molecules and Materials (IMM) , Radboud University , 6525 AJ Nijmegen , The Netherlands
| | - K N Houk
- Department of Chemistry and Biochemistry , University of California , Los Angeles , California 90095 , United States
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42
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Ohkuma T, Arai N. Construction of Unique Heterocyclic Frameworks by Photochemical Reaction of 5- and 6-Membered Heteroaromatics. HETEROCYCLES 2018. [DOI: 10.3987/rev-18-880] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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43
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Palma A, Artelsmair M, Wu G, Lu X, Barrow SJ, Uddin N, Rosta E, Masson E, Scherman OA. Cucurbit[7]uril as a Supramolecular Artificial Enzyme for Diels-Alder Reactions. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201706487] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Aniello Palma
- Melville Laboratory for Polymer Synthesis Department of Chemistry; University of Cambridge; Lensfield Road Cambridge CB2 1EW UK
| | - Markus Artelsmair
- Melville Laboratory for Polymer Synthesis Department of Chemistry; University of Cambridge; Lensfield Road Cambridge CB2 1EW UK
| | - Guanglu Wu
- Melville Laboratory for Polymer Synthesis Department of Chemistry; University of Cambridge; Lensfield Road Cambridge CB2 1EW UK
| | - Xiaoyong Lu
- Department of Chemistry and Biochemistry; Ohio University; Athens Ohio 45701 USA
| | - Steven J. Barrow
- Melville Laboratory for Polymer Synthesis Department of Chemistry; University of Cambridge; Lensfield Road Cambridge CB2 1EW UK
| | - Najib Uddin
- Department of Chemistry; King's College London; London SE1 1DB UK
| | - Edina Rosta
- Department of Chemistry; King's College London; London SE1 1DB UK
| | - Eric Masson
- Department of Chemistry and Biochemistry; Ohio University; Athens Ohio 45701 USA
| | - Oren A. Scherman
- Melville Laboratory for Polymer Synthesis Department of Chemistry; University of Cambridge; Lensfield Road Cambridge CB2 1EW UK
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44
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Palma A, Artelsmair M, Wu G, Lu X, Barrow SJ, Uddin N, Rosta E, Masson E, Scherman OA. Cucurbit[7]uril as a Supramolecular Artificial Enzyme for Diels-Alder Reactions. Angew Chem Int Ed Engl 2017; 56:15688-15692. [DOI: 10.1002/anie.201706487] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Indexed: 11/10/2022]
Affiliation(s)
- Aniello Palma
- Melville Laboratory for Polymer Synthesis Department of Chemistry; University of Cambridge; Lensfield Road Cambridge CB2 1EW UK
| | - Markus Artelsmair
- Melville Laboratory for Polymer Synthesis Department of Chemistry; University of Cambridge; Lensfield Road Cambridge CB2 1EW UK
| | - Guanglu Wu
- Melville Laboratory for Polymer Synthesis Department of Chemistry; University of Cambridge; Lensfield Road Cambridge CB2 1EW UK
| | - Xiaoyong Lu
- Department of Chemistry and Biochemistry; Ohio University; Athens Ohio 45701 USA
| | - Steven J. Barrow
- Melville Laboratory for Polymer Synthesis Department of Chemistry; University of Cambridge; Lensfield Road Cambridge CB2 1EW UK
| | - Najib Uddin
- Department of Chemistry; King's College London; London SE1 1DB UK
| | - Edina Rosta
- Department of Chemistry; King's College London; London SE1 1DB UK
| | - Eric Masson
- Department of Chemistry and Biochemistry; Ohio University; Athens Ohio 45701 USA
| | - Oren A. Scherman
- Melville Laboratory for Polymer Synthesis Department of Chemistry; University of Cambridge; Lensfield Road Cambridge CB2 1EW UK
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45
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Cowie TY, Veguillas M, Rae RL, Rougé M, Żurek JM, Prentice AW, Paterson MJ, Bebbington MWP. Intramolecular Nitrofuran Diels-Alder Reactions: Extremely Substituent-Tolerant Cycloadditions via Asynchronous Transition States. J Org Chem 2017; 82:6656-6670. [PMID: 28574257 DOI: 10.1021/acs.joc.7b00781] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nitrofurans undergo intramolecular Diels-Alder reactions with tethered electron-poor dienophiles more rapidly and in higher yield than non-nitrated furans. Computational studies indicate that increased stabilization of a partial positive charge on the nitro-substituted carbon in both transition state and product is the driving force for these reactions. Frontier molecular orbital energy differences indicate a switch from normal to inverse electron demand upon nitration. There does not appear to be a contribution from any differences in aromatic stabilization energy between furans and nitrofurans. Calculations show that the nitrofuran reactions proceed via a highly asynchronous transition state allowing easier bond formation between two sterically hindered carbons.
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Affiliation(s)
- Thomas Y Cowie
- School of EPS-Chemical Sciences, Heriot Watt University , Edinburgh, EH14 4AS, U.K
| | - Marcos Veguillas
- School of EPS-Chemical Sciences, Heriot Watt University , Edinburgh, EH14 4AS, U.K
| | - Robert L Rae
- School of EPS-Chemical Sciences, Heriot Watt University , Edinburgh, EH14 4AS, U.K
| | - Mathilde Rougé
- School of EPS-Chemical Sciences, Heriot Watt University , Edinburgh, EH14 4AS, U.K
| | - Justyna M Żurek
- School of EPS-Chemical Sciences, Heriot Watt University , Edinburgh, EH14 4AS, U.K
| | - Andrew W Prentice
- School of EPS-Chemical Sciences, Heriot Watt University , Edinburgh, EH14 4AS, U.K
| | - Martin J Paterson
- School of EPS-Chemical Sciences, Heriot Watt University , Edinburgh, EH14 4AS, U.K
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46
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Mechanistic studies on Diels-Alder [4 + 2] cycloaddition reactions of α,β-substituted cyclobutenones: Role of substituents in regio- and stereoselectivity. Tetrahedron 2016. [DOI: 10.1016/j.tet.2016.10.063] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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47
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Sexton T, Kraka E, Cremer D. Extraordinary Mechanism of the Diels–Alder Reaction: Investigation of Stereochemistry, Charge Transfer, Charge Polarization, and Biradicaloid Formation. J Phys Chem A 2016; 120:1097-111. [DOI: 10.1021/acs.jpca.5b11493] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Thomas Sexton
- Computational
and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314, United States
| | - Elfi Kraka
- Computational
and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314, United States
| | - Dieter Cremer
- Computational
and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314, United States
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48
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Hatae N, Kaji A, Okada C, Toyota E. Tandem [4+2] Cycloaddition/Aromatization Sequence of Allenyl 2-Bromo-3-vinylcyclohex-2-enyl Thioether to Naphtho[1,8-bc]thiophene. HETEROCYCLES 2015. [DOI: 10.3987/com-14-s(k)48] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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49
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Grüber R, Monari A, Dumont E. Stability of the Guanine Endoperoxide Intermediate: A Computational Challenge for Density Functional Theory. J Phys Chem A 2014; 118:11612-9. [DOI: 10.1021/jp508330r] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Raymond Grüber
- Laboratoire
de Chimie, UMR 5182 CNRS, École Normale Supérieure de Lyon, 46, allée d’Italie, 69364 Lyon Cedex 07, France
| | - Antonio Monari
- Université de Lorraine Nancy, Théorie-Modélisation-Simulation,
SRSMC, Boulevard des Aiguillettes 54506, Vandoeuvre-lès-Nancy, France
- CNRS,
Théorie-Modélisation-Simulation, SRSMC, Boulevard des
Aiguillettes 54506, Vandoeuvre-lès-Nancy, France
| | - Elise Dumont
- Laboratoire
de Chimie, UMR 5182 CNRS, École Normale Supérieure de Lyon, 46, allée d’Italie, 69364 Lyon Cedex 07, France
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50
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Mukhina OA, Kumar NN, Cowger TM, Kutateladze AG. Photoassisted diversity-oriented synthesis: accessing 2,6-epoxyazocane (oxamorphan) cores. J Org Chem 2014; 79:10956-71. [PMID: 25370821 PMCID: PMC4242042 DOI: 10.1021/jo5019848] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Indexed: 11/29/2022]
Abstract
The modular synthesis of photoprecursors and their photoinduced cyclization into substituted 1-benzazocanes of two distinct topologies is described. The key step producing an extended polyheterocyclic system involves the photogeneration of azaxylylenes and their subsequent intramolecular cycloaddition with furan-containing pendants tethered either via the aniline nitrogen or through the carbonyl group containing arm. The primary photoproducts-secondary or tertiary anilines which are not acylated at the nitrogen atom-undergo facile acid-catalyzed or spontaneous ring-opening-ring-closing rearrangement to yield fused polyheterocyclic structures possessing a 2,6-epoxyazocane (or oxamorphan) core.
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Affiliation(s)
- Olga A. Mukhina
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, United States
| | - N. N.
Bhuvan Kumar
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, United States
| | - Teresa M. Cowger
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, United States
| | - Andrei G. Kutateladze
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, United States
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