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Kadiyam RK, Sangolkar AA, Faizan M, Pawar R. Bispericyclic Ambimodal Dimerization of Pentafulvene: The Origin of Asynchronicity and Kinetic Selectivity of the Endo Transition State. J Org Chem 2024; 89:6813-6825. [PMID: 38661667 DOI: 10.1021/acs.joc.4c00186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
The propensity of fulvenes to undergo dimerization has long been known, although the in-depth mechanism and electronic behavior during dimerization are still elusive. Herein, we made an attempt to gain insights into the reactivity of pentafulvene for Diels-Alder (DA) and [6 + 4]-cycloadditions via conventional and ambimodal routes. The result emphasizes that pentafulvene dimerization preferentially proceeds through a unique bifurcation mechanism where two DA pathways merge together to produce two degenerate [4 + 2]-cycloadducts from a single TS. Despite the [6 + 4]-cycloadduct being thermodynamically preferred, [4 + 2]-cycloaddition reactions are kinetically driven. Singlet biradicaloid is involved in through-space 6e- delocalization as a secondary orbital interaction that originates asynchronicity and stabilizes the bispericyclic transition state (TS). The transformation of various actively participating intrinsic bonding orbitals (IBOs) unambiguously forecasts the formation of multiple products from a single TS and rationalizes the mechanism of ambimodal reactions that are rather difficult to probe with other analyses. The changes in active IBOs clearly distinguish the conventional reactions from bifurcation reactions and can be employed to characterize and confirm the ambimodal mechanism. This report gains a crucial theoretical insight into the mechanism of bifurcation, the origin of asynchronicity, and electronic behavior in ambimodal TS, which will certainly be of enormous value for future studies.
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Affiliation(s)
- Rama Krishna Kadiyam
- Laboratory of Advanced Computation and Theory for Materials and Chemistry, Department of Chemistry, National Institute of Technology Warangal (NITW), Warangal, Telangana 506004, India
| | - Akanksha Ashok Sangolkar
- Laboratory of Advanced Computation and Theory for Materials and Chemistry, Department of Chemistry, National Institute of Technology Warangal (NITW), Warangal, Telangana 506004, India
| | - Mohmmad Faizan
- Laboratory of Advanced Computation and Theory for Materials and Chemistry, Department of Chemistry, National Institute of Technology Warangal (NITW), Warangal, Telangana 506004, India
| | - Ravinder Pawar
- Laboratory of Advanced Computation and Theory for Materials and Chemistry, Department of Chemistry, National Institute of Technology Warangal (NITW), Warangal, Telangana 506004, India
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2
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Sangolkar AA, Kadiyam RK, Pawar R. Novel route to enhance the thermo-optical performance of bicyclic diene photoswitches for solar thermal batteries. Beilstein J Org Chem 2024; 20:1053-1068. [PMID: 38774273 PMCID: PMC11106670 DOI: 10.3762/bjoc.20.93] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Accepted: 04/26/2024] [Indexed: 05/24/2024] Open
Abstract
Harnessing solar energy by employing chemical photoswitches in molecular solar thermal (MOST) energy storage systems is a topic of appealing research interest. However, incorporating all the features desired for an ideal MOST system in a single photoswitching couple is challenging. Inspired by experimental synthesis, herein we report our attempt to enhance both the thermochemical and photophysical properties in a single-bridged bicyclic diene (BBD)-based photoswitch by elongating the unsaturated bridge with different heteroatomic units. To elucidate the best elongation unit, the energy storage capacity and the TBR barriers were accounted using the DLPNO-CCSD(T) and (8,8)-CASPT2 methods, respectively. The photophysical properties including the absorption onset, excitation wavelengths, and the absorption intensities were extensively investigated with the time-dependent calculations. The result provides information on the most versatile solvent to exhibit the best photoswitching behaviour which is beneficial for real-life energy storage applications. Additionally, the stability and reversibility of the photoswitching system with elongated unsaturated bridges have also been assessed. By means of the studied modification, the storage energy of 158.57 kJ/mol, energy storage density of 1.48 MJ/kg, TBR barrier of 136.36 kJ/mol, and the absorption onset of 305.00 nm is achieved in acetonitrile. These values are substantially higher when compared with the storage energy (96.06 kJ/mol), energy storage density (1.04 MJ/kg), and TBR barrier (121.76 kJ/mol) of prototype NBD/QC in the gas phase. The outcomes render useful insights into the stability and properties of bicyclic diene-based photoswitches having elongated unsaturated bridges and indeed paves the way for the rational design of practical MOST systems.
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Affiliation(s)
- Akanksha Ashok Sangolkar
- Laboratory of Advanced Computation and Theory for Materials and Chemistry, Department of Chemistry, National Institute of Technology Warangal (NITW), Warangal, Telangana-506004, India
| | - Rama Krishna Kadiyam
- Laboratory of Advanced Computation and Theory for Materials and Chemistry, Department of Chemistry, National Institute of Technology Warangal (NITW), Warangal, Telangana-506004, India
| | - Ravinder Pawar
- Laboratory of Advanced Computation and Theory for Materials and Chemistry, Department of Chemistry, National Institute of Technology Warangal (NITW), Warangal, Telangana-506004, India
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3
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Zhang P, Yu ZX. Dynamically or Kinetically Controlled? Computational Study of the Mechanisms of Electrophilic Aminoalkenylation of Heteroaromatics with Keteniminium Ions. J Org Chem 2024; 89:4326-4335. [PMID: 38506441 DOI: 10.1021/acs.joc.3c02379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
Quantum chemical calculations and molecular dynamics simulations were applied to study the electrophilic aminoalkenylation of heteroaromatics with keniminium ions. Post-transition state bifurcation (PTSB) was found in the electrophilic addition step for the aminoalkenylation of pyrroles and indoles, and the selectivity for these reactions was dynamically controlled. However, the aminoalkenylation of furan was kinetically controlled because no apparent PTSB was found in the electrophilic addition step. The substituents on the keteniminium ions can also affect the dynamic results for the aminoalkenylations to pyrroles: the C2-aminoalkenylated product is much more favored over the C3-aminoalkenylated product for keteniminium ions with electron-donating substituents, while the product ratio (C2 product/C3 product) decreased when stronger electron-withdrawing substituents were applied.
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Affiliation(s)
- Pan Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Zhi-Xiang Yu
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
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4
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Lamhauge JN, McLeod DA, Barløse CL, Oliver GA, Viborg L, Warburg T, Anker Jørgensen K. Enantioselective Synthesis of Tropane Scaffolds by an Organocatalyzed 1,3-Dipolar Cycloaddition of 3-Oxidopyridinium Betaines and Dienamines. Chemistry 2023; 29:e202301830. [PMID: 37318111 DOI: 10.1002/chem.202301830] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 06/15/2023] [Accepted: 06/15/2023] [Indexed: 06/16/2023]
Abstract
Tropane alkaloids constitute a compound-class which is structurally defined by a central 8-azabicyclo[3.2.1]octane core. A diverse bioactivity profile combined with an unusual aza-bridged bicyclic framework has made tropanes molecules-of-interest within organic chemistry. Enantioselective examples of (5+2) cycloadditions between 3-oxidopyridinium betaines and olefins remain unexplored, despite 3-oxidopyridinium betaines being useful reagents in organic synthesis. The first asymmetric (5+2) cycloaddition of 3-oxidopyridinium betaines is reported, affording tropane derivatives in up to quantitative yield and with excellent control of peri-, regio-, diastereo-, and enantioselectivity. The reactivity is enabled by dienamine-activation of α,β-unsaturated aldehydes combined with in situ formation of the pyridinium reaction-partner. A simple N-deprotection protocol allows for liberation of the tropane alkaloid motif, and synthetic elaborations of the cycloadducts demonstrate their synthetic utility to achieve highly diastereoselective modification around the bicyclic framework. DFT computations suggest a stepwise mechanism where regio- and stereoselectivity are defined during the first bond-forming step in which the pyridinium dipole exerts critical conformational control over its dienamine partner. In the second bond-forming step, a kinetic preference toward an initial (5+4) cycloadduct was identified; however, a lack of catalyst turn-over, reversibility, and thermodynamic bias favoring a (5+2) cycloadduct rendered the reaction fully periselective.
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Affiliation(s)
- Johannes N Lamhauge
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - David A McLeod
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Casper L Barløse
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Gwyndaf A Oliver
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Laura Viborg
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Tobias Warburg
- 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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5
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Yamamoto Y, Shizume Y, Tazawa S, Yasui T. Oxidopyridinium Cycloadditions Revisited: A Combined Computational and Experimental Study on the Reactivity of 1-(2-Pyrimidyl)-3-oxidopyridinium Betaine. J Org Chem 2023. [PMID: 36802575 DOI: 10.1021/acs.joc.2c02971] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
To investigate the effect of N-substituents on their reactivity and selectivity of oxidopyridinium betaines, we performed density functional theory (DFT) calculations of model cycloadditions with N-methylmaleimide and acenaphthylene. The theoretically expected results were compared with the experimental results. Subsequently, we demonstrated that 1-(2-pyrimidyl)-3-oxidopyridinium can be used for (5 + 2) cycloadditions with various electron-deficient alkenes, dimethyl acetylenedicarboxylate, acenaphthylene, and styrene. In addition, a DFT analysis of the cycloaddition of 1-(2-pyrimidyl)-3-oxidopyridinium with 6,6-dimethylpentafulvene suggested the possibility of pathway bifurcations involving a (5 + 4)/(5 + 6) ambimodal transition state, although only (5 + 6) cycloadducts were experimentally observed. A related (5 + 4) cycloaddition was observed in the reaction of 1-(2-pyrimidyl)-3-oxidopyridinium with 2,3-dimethylbut-1,3-diene.
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Affiliation(s)
- Yoshihiko Yamamoto
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Yudai Shizume
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Syunji Tazawa
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Takeshi Yasui
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan
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6
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Tu J, Ripa RA, Kelley SP, Harmata M. Intramolecular (4+3) Cycloadditions of Oxidopyridinium Ions: Towards Daphnicyclidin A. Chemistry 2022; 28:e202200370. [PMID: 35612968 DOI: 10.1002/chem.202200370] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Indexed: 12/15/2022]
Abstract
N-alkylation of 5-hydroxynicotinic acid esters with electrophiles containing diene functionality produces salts that undergo intramolecular (4+3) cycloaddition reactions upon heating in the presence of base. Initial studies used a three-carbon tether to join the pyridinium ion and diene, revealing some aspects of the inherent selectivity of the reaction with such substrates. Much more challenging was the synthesis of related species possessing only a two-carbon tether. Nevertheless, the cycloaddition of such compounds was successful, leading directly to the ABC ring system of the alkaloid daphnicyclidin A.
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Affiliation(s)
- Jianzhuo Tu
- Department of Chemistry, University of Missouri-Columbia, 601 S. College Avenue, Columbia, Missouri, 65211, USA
| | - Rawshan A Ripa
- Department of Chemistry, University of Missouri-Columbia, 601 S. College Avenue, Columbia, Missouri, 65211, USA
| | - Steven P Kelley
- Department of Chemistry, University of Missouri-Columbia, 601 S. College Avenue, Columbia, Missouri, 65211, USA
| | - Michael Harmata
- Department of Chemistry, University of Missouri-Columbia, 601 S. College Avenue, Columbia, Missouri, 65211, USA
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7
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Wang X, Zhang C, Jiang Y, Wang W, Zhou Y, Chen Y, Zhang B, Tan RX, Ge HM, Yang ZJ, Liang Y. Influence of Water and Enzyme on the Post-Transition State Bifurcation of NgnD-Catalyzed Ambimodal [6+4]/[4+2] Cycloaddition. J Am Chem Soc 2021; 143:21003-21009. [PMID: 34851644 DOI: 10.1021/jacs.1c10760] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The enzyme NgnD catalyzes an ambimodal cycloaddition that bifurcates to [6+4]- and [4+2]-adducts. Both products have been isolated in experiments, but it remains unknown how enzyme and water influence the bifurcation selectivity at the femtosecond time scale. Here, we study the impact of water and enzyme on the post-transition state bifurcation of NgnD-catalyzed [6+4]/[4+2] cycloaddition by integrating quantum mechanics/molecular mechanics quasiclassical dynamics simulations and biochemical assays. The ratio of [6+4]/[4+2] products significantly differs in the gas phase, water, and enzyme. Biochemical assays were employed to validate computational predictions. The study informs how water and enzyme affect the bifurcation selectivity through perturbation of the reaction dynamics in the femtosecond time scale, revealing the fundamental roles of condensed media in dynamically controlling the chemical selectivity for biosynthetic reactions.
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Affiliation(s)
- Xin Wang
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, Chemistry and Biomedicine Innovation Center, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.,Henan-Macquarie University Joint Centre for Biomedical Innovation, School of Life Sciences, Henan University, Kaifeng, Henan 475004, China
| | - Chun Zhang
- School of Pharmaceutical Sciences, Jiangnan University, Wuxi 214122, China
| | - Yaoyukun Jiang
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Wen Wang
- State Key Laboratory of Pharmaceutical Biotechnology, Institute of Functional Biomolecules, Chemistry and Biomedicine Innovation Center, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Yuan Zhou
- Henan-Macquarie University Joint Centre for Biomedical Innovation, School of Life Sciences, Henan University, Kaifeng, Henan 475004, China
| | - Yu Chen
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, Chemistry and Biomedicine Innovation Center, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Bo Zhang
- State Key Laboratory of Pharmaceutical Biotechnology, Institute of Functional Biomolecules, Chemistry and Biomedicine Innovation Center, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Ren Xiang Tan
- State Key Laboratory of Pharmaceutical Biotechnology, Institute of Functional Biomolecules, Chemistry and Biomedicine Innovation Center, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Hui Ming Ge
- State Key Laboratory of Pharmaceutical Biotechnology, Institute of Functional Biomolecules, Chemistry and Biomedicine Innovation Center, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Zhongyue J Yang
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States.,Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States.,Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States.,Data Science Institute, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Yong Liang
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, Chemistry and Biomedicine Innovation Center, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
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8
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Lu Y, Tantillo DJ. Comparison of (5 + 2) Cycloadditions Involving Oxidopyrylium and Oxidopyridinium Ions: Relative Reactivities. J Org Chem 2021; 86:8652-8659. [PMID: 34111355 DOI: 10.1021/acs.joc.1c00396] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A variety of (5 + 2) cycloaddition reactions involving oxidopyridinium and oxidopyrylium zwitterions are compared to investigate the effects of nitrogen-for-oxygen substitution on reactivity. Activation barriers for nitrogen-containing systems are predicted to be larger than those for analogous oxygen-containing systems. Correlations between barrier heights and synchronicity of C-C bond formation, changes to aromaticity, reactant distortion, and interaction energies between zwitterions and alkenes were assessed, leading to the conclusion that reactivity depends more on distortion effects (including aromaticity loss) than on interaction effects (such as those associated with highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) interactions).
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Affiliation(s)
- Yining Lu
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Dean J Tantillo
- Department of Chemistry, University of California, Davis, California 95616, United States
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9
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Kpante M, Wolf LM. Pathway Bifurcations in the Activation of Allylic Halides by Palladium and Their Influence on the Dynamics of η 1 and η 3 Allyl Intermediates. J Org Chem 2021; 86:9637-9650. [PMID: 34190566 DOI: 10.1021/acs.joc.1c00891] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Transition-metal-catalyzed allylic substitution often exhibits complex product selectivity patterns, which have been primarily attributed to π ↔ σ ↔ π isomerization of the η1 and η3 allyl intermediates. Product selectivity may be even further complicated if η1- and η3-allyls share a single transition state (TS), leading to their formation resulting in a post-transition-state bifurcation (PTSB). In this work, density functional theory calculations using ab initio molecular dynamics (AIMD) have been carried out that support the presence of a PTSB in Pd-catalyzed allylic halide activation directly influencing product selectivity. The AIMD results initiated from the TS predict the η1-allyl to be favored in the gas phase and a low dielectric (ε < 2.5) for trialkylphosphines, while the selectivity shifts toward the η3-allyl in higher dielectrics. The minimum energy path is also predicted to shift in product preference, consistent with the dynamics predictions. The bifurcation in allylic chloride activation is predicted to largely favor the η3-allyl at any solvent polarity. A PTSB was also discovered to be present in Ni and Pt allylic activation but with less bifurcation. These results offer a unique view into the mechanism of metal-catalyzed allylic substitution.
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Affiliation(s)
- Malkaye Kpante
- Department of Chemistry, Kennedy College of Sciences, University of Massachusetts Lowell, Lowell, Massachusetts 01854, United States
| | - Lawrence M Wolf
- Department of Chemistry, Kennedy College of Sciences, University of Massachusetts Lowell, Lowell, Massachusetts 01854, United States
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10
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Zhang K, Wang Y, Zhu H, Peng Q. Advances on Quasi-classical Molecular Dynamics of Organic Reaction Mechanisms. CHINESE J ORG CHEM 2021. [DOI: 10.6023/cjoc202102036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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11
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Tantillo DJ. Beyond transition state theory—Non-statistical dynamic effects for organic reactions. ADVANCES IN PHYSICAL ORGANIC CHEMISTRY 2021. [DOI: 10.1016/bs.apoc.2021.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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12
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Hussein AA, Ma Y, Al‐Yasari A. Hypervalent Iodine‐Mediated Styrene Hetero‐ and Homodimerization Initiation Proceeds with Two‐Electron Reductive Cleavage. European J Org Chem 2020. [DOI: 10.1002/ejoc.202001295] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
| | - Yumiao Ma
- BSJ Institue, Haidian 100084 Beijing People's Republic of China
| | - Ahmed Al‐Yasari
- School of Chemistry University of East Anglia NR4 7TJ Norwich United Kingdom
- Department of Chemistry Faculty of Sciences University of Kerbala Kerbala Iraq
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13
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Hussein AA, Al-Hadedi AAM, Mahrath AJ, Moustafa GAI, Almalki FA, Alqahtani A, Shityakov S, Algazally ME. Mechanistic investigations on Pinnick oxidation: a density functional theory study. ROYAL SOCIETY OPEN SCIENCE 2020; 7:191568. [PMID: 32257322 PMCID: PMC7062072 DOI: 10.1098/rsos.191568] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 01/13/2020] [Indexed: 05/04/2023]
Abstract
A computational study on Pinnick oxidation of aldehydes into carboxylic acids using density functional theory (DFT) calculations has been evaluated with the (SMD)-M06-2X/aug-pVDZ level of theory, leading to an important understanding of the reaction mechanism that agrees with the experimental observations and explaining the substantial role of acid in driving the reaction. The DFT results elucidated that the first reaction step (FRS) proceeds in a manner where chlorous acid reacts with the aldehyde group through a distorted six-membered ring transition state to give a hydroxyallyl chlorite intermediate that undergoes a pericyclic fragmentation to release the carboxylic acid as a second reaction step (SRS). 1H NMR experiments and simulations showed that hydrogen bonding between carbonyl and t-butanol is unlikely to occur. Additionally, it was found that the FRS is a rate-determining and thermoneutral step, whereas SRS is highly exergonic with a low energetic barrier due to the Cl(III) → Cl(II) reduction. Frontier molecular orbital analysis, intrinsic reaction coordinate, molecular dynamics and distortion/interaction analysis further supported the proposed mechanism.
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Affiliation(s)
- Aqeel A. Hussein
- Faculty of Dentistry, University of Al-Ameed, Karbala PO Box 198, Iraq
- Department of Chemistry, University of Southampton, Southampton, Hampshire SO17 1BJ, UK
| | | | - Alaa J. Mahrath
- Department of Chemistry and Biochemistry, College of Medicine, University of Babylon, Babylon, Iraq
| | - Gamal A. I. Moustafa
- Department of Chemistry, University of Southampton, Southampton, Hampshire SO17 1BJ, UK
- Department of Medicinal Chemistry, Faculty of Pharmacy, Minia University, Minia 61519, Egypt
| | - Faisal A. Almalki
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Umm Al-Qura University, Makkah 21955, Saudi Arabia
| | - Alaa Alqahtani
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Umm Al-Qura University, Makkah 21955, Saudi Arabia
| | - Sergey Shityakov
- Department of Anesthesia and Critical Care, University of Würzburg, 97080 Würzburg, Germany
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14
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Sangolkar AA, Pawar R. Prediction of the [4 + 2]- and [5 + 4]-cycloaddition reactions in zig-zag carbon nanotubes via an ambimodal transition state: density functional theory calculations. RSC Adv 2020; 10:11111-11120. [PMID: 35495313 PMCID: PMC9050518 DOI: 10.1039/c9ra10252c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 02/26/2020] [Indexed: 11/21/2022] Open
Abstract
A unique type of chemical reaction known as an ambimodal reaction has drawn tremendous attention owing to its intriguing feature of forming multiple (two or more) products from the same (single) transition state. In contrast to conventional reactions, bifurcation of the potential energy surface takes place in ambimodal reactions. Density functional theory (DFT) based calculations were performed to probe the Diels–Alder (DA) cycloaddition reactions of various carbon nanotubes (CNTs) with 1,3-butadiene. The present investigation reveals the possibility of ambimodal transition state formation on a potential energy surface (PES) corresponding to an unusual [5 + 4]-cycloadduct along with the conventional [4 + 2]-cycloadduct. The ground state of the [5 + 4]-cycloadduct obtained from butadiene and the H-terminated CNTs is a triplet (3T) state, but on the other hand the [4 + 2]-cycloadduct is a singlet (1S) state. The [5 + 4]-adduct is energetically more stable in comparison with the [4 + 2]-adduct. The possibility of the formation of the [5 + 4]-adduct is validated using frontier molecular orbitals. The length of the nanotube significantly influences the overall kinetics and thermodynamics of the reaction. A DFT study has been performed to unveil the ambimodal reaction in H-terminated CNTs.![]()
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Affiliation(s)
| | - Ravinder Pawar
- Department of Chemistry
- National Institute of Technology (NIT) Warangal
- India
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15
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Bejcek LP, Garimallaprabhakaran AK, Suyabatmaz DM, Greer A, Hersh WH, Greer EM, Murelli RP. Maltol- and Allomaltol-Derived Oxidopyrylium Ylides: Methyl Substitution Pattern Kinetically Influences [5 + 3] Dimerization versus [5 + 2] Cycloaddition Reactions. J Org Chem 2019; 84:14670-14678. [PMID: 31603325 PMCID: PMC6982524 DOI: 10.1021/acs.joc.9b02137] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Oxidopyrylium ylides are useful intermediates in synthetic organic chemistry because of their capability of forming structurally complex cycloadducts. They can also self-dimerize via [5 + 3] cycloaddition, which is an oft-reported side reaction that can negatively impact [5 + 2] cycloadduct yields and efficiency. In select instances, these dimers can be synthesized and used as the source of oxidopyrylium ylide, although the generality of this process remains unclear. Thus, how the substitution pattern governs both dimerization and cycloaddition reactions is of fundamental interest to probe factors to regulate them. The following manuscript details our findings that maltol-derived oxidopyrylium ylides (i.e., with ortho methyl substitution relative to oxide) can be trapped prior to dimerization more efficiently than the regioisomeric allomaltol-derived ylide (i.e., with a para methyl substitution relative to oxide). Density functional theory studies provide evidence in support of a sterically (kinetically) controlled mechanism, whereby gauche interactions between appendages of the approaching maltol-derived ylides are privileged by higher barriers for dimerization and thus are readily intercepted by dipolarophiles via [5 + 2] cycloadditions.
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Affiliation(s)
- Lauren P Bejcek
- Department of Chemistry , Brooklyn College, The City University of New York , Brooklyn , New York 11210 , United States
- PhD Program in Chemistry , The Graduate Center of the City University of New York , New York , New York 10016 , United States
| | - Aswin K Garimallaprabhakaran
- Department of Chemistry , Brooklyn College, The City University of New York , Brooklyn , New York 11210 , United States
| | - Duygu M Suyabatmaz
- Department of Chemistry , Brooklyn College, The City University of New York , Brooklyn , New York 11210 , United States
| | - Alexander Greer
- Department of Chemistry , Brooklyn College, The City University of New York , Brooklyn , New York 11210 , United States
- PhD Program in Chemistry , The Graduate Center of the City University of New York , New York , New York 10016 , United States
| | - William H Hersh
- PhD Program in Chemistry , The Graduate Center of the City University of New York , New York , New York 10016 , United States
- Department of Chemistry and Biochemistry , Queens College, City University of New York , Queens , New York 11367 , United States
| | - Edyta M Greer
- Department of Natural Sciences , Baruch College, City University of New York , New York , New York 10010 , United States
| | - Ryan P Murelli
- Department of Chemistry , Brooklyn College, The City University of New York , Brooklyn , New York 11210 , United States
- PhD Program in Chemistry , The Graduate Center of the City University of New York , New York , New York 10016 , United States
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