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Dempsey SH, Cao W, Wang XB, Kass SR. Anion-Activated Bases and Nucleophiles Characterized by Photoelectron Spectroscopy. J Phys Chem A 2023; 127:8828-8833. [PMID: 37844075 DOI: 10.1021/acs.jpca.3c04479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
Negative ion photoelectron spectra at 20 K along with ab initio [CCSD(T)] and M06-2X density functional theory calculations are reported for a series of six basic and nucleophilic pyridine derivatives with an anionic substituent [i.e., 3- and 4-PyrBX3-, where X = F, 4-t-BuC6H4, 4-MeOC6H4, and 3,5-(MeO)2C6H3]. Vertical detachment energies (VDEs) of these charge-activated reagents span from 4.50-5.85 eV and are well reproduced by M06-2X/aug-cc-pVTZ and CCSD(T)/maug-cc-pVTZ computations. Surprisingly, the VDEs are found to correlate with the SN2 reactivity of the PPh4+ salts of the substituted pyridine anions with 1-iodooctane in dichloromethane. This provides an experimental measure of the nucleophilicity of these charge-activated anions, which represent a new class of chemical reagent.
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Affiliation(s)
- Stephen H Dempsey
- Department of Chemistry, University of Minnesota 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Wenjin Cao
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Xue-Bin Wang
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Steven R Kass
- Department of Chemistry, University of Minnesota 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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2
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Liu T, Shen X, Liu Z, Zhang F, Liu JJ. An electron-deficient MOF as an efficient electron-transfer catalyst for selective oxidative carbon-carbon coupling of 2,6-di- tert-butylphenol. Dalton Trans 2022; 51:8234-8239. [PMID: 35575225 DOI: 10.1039/d2dt00869f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Naphthalene diimides (NDIs), a type of electron-deficient dye molecule with high quadrupole moment and excellent redox activity, have been utilized in various fields, such as energy transfer, chemical sensing, anion transport, and photo-/electrochromic materials. In this study, an electron-deficient metal-organic framework with one-dimensional channels, Eu2(BBNDI)3(DMF)2 (MOF 1) (H2BBNDI = N,N'-bis(3-benzoic acid)naphthalene diimide), was successfully constructed based on the naphthalene diimide derivative. Because of the generation of NDI radicals by electron transfer between components, this material exhibits fast-responsive reversible photochromic properties. Moreover, it shows high efficiency and selective oxidation of 2,6-di-tert-butylphenol to its quinone derivative, aldehyde, and dimeric or trimeric phenol derivative by controlling the reaction conditions.
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Affiliation(s)
- Teng Liu
- College of Chemistry and Environmental Science, Qujing Normal University, Qujing 655011, China.
| | - Xianfu Shen
- College of Chemistry and Environmental Science, Qujing Normal University, Qujing 655011, China.
| | - Zhengfen Liu
- College of Chemistry and Environmental Science, Qujing Normal University, Qujing 655011, China.
| | - Feng Zhang
- College of Chemistry and Environmental Science, Qujing Normal University, Qujing 655011, China.
| | - Jian-Jun Liu
- College of Chemistry and Environmental Science, Qujing Normal University, Qujing 655011, China.
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3
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Smajlagic I, White B, Azeez O, Pilkington M, Dudding T. Organocatalysis Linked to Charge-Enhanced Acidity with Superelectrophilic Traits. ACS Catal 2022. [DOI: 10.1021/acscatal.1c05296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ivor Smajlagic
- Department of Chemistry, Brock University, St. Catharines L2S 3A1, Canada
| | - Brandon White
- Department of Chemistry, Brock University, St. Catharines L2S 3A1, Canada
| | - Oyindamola Azeez
- Department of Chemistry, Brock University, St. Catharines L2S 3A1, Canada
| | - Melanie Pilkington
- Department of Chemistry, Brock University, St. Catharines L2S 3A1, Canada
| | - Travis Dudding
- Department of Chemistry, Brock University, St. Catharines L2S 3A1, Canada
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4
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Dale HJA, Leach AG, Lloyd-Jones GC. Heavy-Atom Kinetic Isotope Effects: Primary Interest or Zero Point? J Am Chem Soc 2021; 143:21079-21099. [PMID: 34870970 DOI: 10.1021/jacs.1c07351] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Chemists have many options for elucidating reaction mechanisms. Global kinetic analysis and classic transition-state probes (e.g., LFERs, Eyring) inevitably form the cornerstone of any strategy, yet their application to increasingly sophisticated synthetic methodologies often leads to a wide range of indistinguishable mechanistic proposals. Computational chemistry provides powerful tools for narrowing the field in such cases, yet wholly simulated mechanisms must be interpreted with great caution. Heavy-atom kinetic isotope effects (KIEs) offer an exquisite but underutilized method for reconciling the two approaches, anchoring the theoretician in the world of calculable observables and providing the experimentalist with atomistic insights. This Perspective provides a personal outlook on this synergy. It surveys the computation of heavy-atom KIEs and their measurement by NMR spectroscopy, discusses recent case studies, highlights the intellectual reward that lies in alignment of experiment and theory, and reflects on the changes required in chemical education in the area.
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Affiliation(s)
- Harvey J A Dale
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K
| | - Andrew G Leach
- School of Health Sciences, The University of Manchester, Stopford Building, Oxford Road, Manchester M13 9PT, U.K
| | - Guy C Lloyd-Jones
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K
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Ranga PK, Ahmad F, Singh G, Tyagi A, Vijaya Anand R. Recent advances in the organocatalytic applications of cyclopropene- and cyclopropenium-based small molecules. Org Biomol Chem 2021; 19:9541-9564. [PMID: 34704583 DOI: 10.1039/d1ob01549d] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The development of novel small molecule-based catalysts for organic transformations has increased noticeably in the last two decades. A very recent addition to this particular research area is cyclopropene- and cyclopropenium-based catalysts. At one point in time, particularly in the mid-20th century, much attention was focused on the structural aspects and physical properties of cyclopropene-based compounds. However, a paradigm shift was observed in the late 20th century, and the focus shifted to the synthetic utility of these compounds. In fact, a wide range of cyclopropene derivatives have been found serving as valuable synthons for the construction of carbocycles, heterocycles and other useful organic compounds. In the last few years, the catalytic applications of cyclopropene/cyclopropenium-based compounds have been uncovered and many synthetic protocols have been developed using cyclopropene-based compounds as organocatalysts. Therefore, the main objective of this review is to highlight recent developments in the catalytic applications of cyclopropene-based small molecules in different areas of organocatalysis such as phase-transfer catalysis (PTC), Brønsted base catalysis, hydrogen-bond donor catalysis, nucleophilic carbene catalysis, and electrophotocatalysis developed within the past two decades.
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Affiliation(s)
- Pavit K Ranga
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, S.A.S Nagar, Manauli (PO), Punjab - 140306, India.
| | - Feroz Ahmad
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, S.A.S Nagar, Manauli (PO), Punjab - 140306, India.
| | - Gurdeep Singh
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, S.A.S Nagar, Manauli (PO), Punjab - 140306, India.
| | - Akshi Tyagi
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, S.A.S Nagar, Manauli (PO), Punjab - 140306, India.
| | - Ramasamy Vijaya Anand
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, S.A.S Nagar, Manauli (PO), Punjab - 140306, India.
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Takagi R, Duong DT. Computational study on N-triflylphosphoramide-catalyzed enantioselective hydroamination of alkenyl thiourea. Org Biomol Chem 2021; 19:8806-8811. [PMID: 34569576 DOI: 10.1039/d1ob01672e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The mechanism of the enantioselective intramolecular hydroamination of alkenyl thiourea catalyzed by chiral binaphthol N-triflylphosphoramide (NPTA) was investigated using density functional theory calculations. This study reveals the details of the hydrogen bonding mode between NPTA and the substrate and indicates the importance of the dual hydrogen binding properties of the thiourea moiety for the reactivity and stereoselectivity of the hydroamination.
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Affiliation(s)
- Ryukichi Takagi
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
| | - Duyen Thi Duong
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
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Murakami H, Yamada A, Michigami K, Takemoto Y. Novel Aza‐Michael Addition‐Asymmetric Protonation to α,β‐Unsaturated Carboxylic Acids with Chiral Thiourea‐Boronic Acid Hybrid Catalysts. ASIAN J ORG CHEM 2021. [DOI: 10.1002/ajoc.202100145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Hiroki Murakami
- Graduate School of Pharmaceutical Sciences Kyoto university 46–29 Shimoadachi-cho, Yoshida, Sakyo-ku Kyoto 606-8501 Japan
| | - Ayano Yamada
- Graduate School of Pharmaceutical Sciences Kyoto university 46–29 Shimoadachi-cho, Yoshida, Sakyo-ku Kyoto 606-8501 Japan
| | - Kenichi Michigami
- Graduate School of Pharmaceutical Sciences Kyoto university 46–29 Shimoadachi-cho, Yoshida, Sakyo-ku Kyoto 606-8501 Japan
| | - Yoshiji Takemoto
- Graduate School of Pharmaceutical Sciences Kyoto university 46–29 Shimoadachi-cho, Yoshida, Sakyo-ku Kyoto 606-8501 Japan
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Ranga PK, Ahmad F, Nager P, Rana PS, Vijaya Anand R. Bis(amino)cyclopropenium Ion as a Hydrogen-Bond Donor Catalyst for 1,6-Conjugate Addition Reactions. J Org Chem 2021; 86:4994-5010. [PMID: 33721500 DOI: 10.1021/acs.joc.0c02940] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The catalytic application of the bis(amino)cyclopropenium ion has been investigated in conjugate addition reactions. The hydrogen atom, which is attached to the cyclopropene ring of bis(amino)cyclopropenium salts, is moderately acidic and can potentially serve as a hydrogen-bond donor catalyst in some organic transformations. This hypothesis has been successfully realized in the 1,6-conjugate addition reactions of p-quinone methides with various nucleophiles such as indole, 2-naphthol, thiols, phenols, and so forth. The spectroscopic studies (NMR and UV-vis) as well as the deuterium isotope labeling studies clearly revealed that the hydrogen atom (C-H) that is present in the cyclopropene ring of the catalyst is indeed solely responsible for catalyzing these transformations. In addition, these studies also strongly indicate that the C-H hydrogen of the cyclopropene ring activates the carbonyl group of the p-quinone methide through hydrogen bonding.
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Affiliation(s)
- Pavit Kumar Ranga
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, Manauli (P.O.), S. A. S. Nagar, Punjab 140306, India
| | - Feroz Ahmad
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, Manauli (P.O.), S. A. S. Nagar, Punjab 140306, India
| | - Prashant Nager
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, Manauli (P.O.), S. A. S. Nagar, Punjab 140306, India
| | - Prabhat Singh Rana
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, Manauli (P.O.), S. A. S. Nagar, Punjab 140306, India
| | - Ramasamy Vijaya Anand
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, Manauli (P.O.), S. A. S. Nagar, Punjab 140306, India
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Smajlagic I, Carlson B, Dudding T. Brønsted Acid Organocatalyzed Three-Component Hydroamidation Reactions of Vinyl Ethers. J Org Chem 2021; 86:4171-4181. [PMID: 33626274 DOI: 10.1021/acs.joc.0c03017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hydroamidation of carbon-carbon double bonds is an attractive strategy for installing nitrogen functionality into molecular scaffolds and, with it, increasing molecular complexity. To date, metal-based approaches have dominated this area of chemical synthesis, despite the drawbacks of air and moisture sensitivity, limited functional group tolerance, toxicity, and/or high cost often associated with using metals. Here, in offering an alternative solution, we disclose an operationally simple, metal-free, one-pot, regioselective, multicomponent synthetic procedure for the hydroamidation of carbon-carbon double bonds. This method features mild reaction conditions and utilizes isocyanides and vinyl ethers for the rapid and modular synthesis of privileged α-oxygenated amide scaffolds. In unraveling the mechanistic underpinning of this non-metal-based reactivity, we present kinetic solvent isotope effect studies, variable time normalization analysis, and density functional theory computations offering insight into the mechanism of this multistep catalytic hydroamidation process.
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Affiliation(s)
- Ivor Smajlagic
- Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON L2S 3A1, Canada
| | - Brenden Carlson
- Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON L2S 3A1, Canada
| | - Travis Dudding
- Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON L2S 3A1, Canada
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Sharma HA, Mennie KM, Kwan EE, Jacobsen EN. Enantioselective Aryl-Iodide-Catalyzed Wagner-Meerwein Rearrangements. J Am Chem Soc 2020; 142:16090-16096. [PMID: 32845619 DOI: 10.1021/jacs.0c08150] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We report a strategy for effecting catalytic, enantioselective carbocationic rearrangements through the intermediacy of alkyl iodanes as stereodefined carbocation equivalents. Asymmetric Wagner-Meerwein rearrangements of β-substituted styrenes are catalyzed by the C2-symmetric aryl iodide 1 to provide access to enantioenriched 1,3-difluorinated molecules possessing interesting and well-defined conformational properties. Hammett and kinetic isotope effect studies, in combination with computational investigations, reveal that two different mechanisms are operative in these rearrangement reactions, with the pathway depending on the identity of the migrating group. In reactions involving alkyl-group migration, intermolecular fluoride attack is product- and enantio-determining. In contrast, reactions in which aryl rearrangement occurs proceed through an enantiodetermining intramolecular 1,2-migration prior to fluorination. The fact that both pathways are promoted by the same chiral aryl iodide catalyst with high enantioselectivity provides a compelling illustration of generality across reaction mechanisms in asymmetric catalysis.
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Affiliation(s)
- Hayden A Sharma
- Department of Chemistry & Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Katrina M Mennie
- Department of Chemistry & Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Eugene E Kwan
- Department of Chemistry & Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Eric N Jacobsen
- Department of Chemistry & Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
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