1
|
Somprasong S, Castiñeira Reis M, Harutyunyan SR. Grignard Reagent Addition to Pyridinium Salts: A Catalytic Approach to Chiral 1,4-Dihydropyridines. ACS Catal 2024; 14:13030-13039. [PMID: 39263543 PMCID: PMC11385375 DOI: 10.1021/acscatal.4c03520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2024] [Revised: 07/29/2024] [Accepted: 08/01/2024] [Indexed: 09/13/2024]
Abstract
Catalytic dearomatization of pyridinium salts is a powerful technique for constructing chiral N-heterocycles, which are crucial in alkaloid natural products and drugs. Despite its potential, progress in metal-catalyzed asymmetric dearomatization of pyridinium derivatives has been limited. Here, we present the enantioselective 1,4-dearomatization of pyridinium salts using Grignard reagents and chiral copper catalysis. This approach yields enantioenriched functionalized 1,4-dihydropyridines. Experimental kinetic isotope effects and density functional theory calculations provide insights into the reaction mechanism, regio- and enantioselectivity, and the rate-limiting step.
Collapse
Affiliation(s)
- Siriphong Somprasong
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands
| | - Marta Castiñeira Reis
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS), Universidade de Santiago de Compostela, C/ Jenaro de la Fuente s/n, Campus Vida, Santiago de Compostela 15782, Spain
| | - Syuzanna R Harutyunyan
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands
| |
Collapse
|
2
|
González JA, Arribas A, Tian P, Díaz-Alonso S, Mascareñas JL, López F, Nevado C. Gold(III) Auracycles Featuring C(sp 3)-Au-C(sp 2) Bonds: Synthesis and Mechanistic Insights into the Cycloauration Step. Angew Chem Int Ed Engl 2024; 63:e202402798. [PMID: 38776235 DOI: 10.1002/anie.202402798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 04/19/2024] [Accepted: 05/22/2024] [Indexed: 05/24/2024]
Abstract
The direct auration of arenes is a key step in numerous gold-catalyzed reactions. Although reported more than 100 years ago, understanding of its underlying mechanism has been hampered by the difficulties in the isolation of relevant intermediates given the propensity of gold(III) species to undergo reductive elimination. Here, we report the synthesis and isolation of a new family of intriguing zwitterionic [C(sp3)^C(sp2)]-auracyclopentanes, as well as of their alkyl-gold(III) precursors and demonstrate their value as mechanistic probes to study the C(sp2)-Au bond-forming event. Experimental investigations employing Kinetic Isotope Effects (KIE), Hammett plot, and Eyring analysis provided important insights into the formation of the auracycle. The data suggest a SEAr mechanism wherein the slowest step might be the π-coordination between the arene and the gold(III) center, en route to the Wheland intermediate. We also show that these auracyclopentanes can work as catalysts in several gold-promoted transformations.
Collapse
Affiliation(s)
- Jorge A González
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Andrés Arribas
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - Puyang Tian
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Sergio Díaz-Alonso
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - José Luis Mascareñas
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - Fernando López
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain
- Misión Biológica de Galicia, Consejo Superior de Investigaciones Científicas (CSIC), 36680, Pontevedra, Spain
| | - Cristina Nevado
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| |
Collapse
|
3
|
Kania MJ, Reyes A, Neufeldt SR. Oxidative Addition of (Hetero)aryl (Pseudo)halides at Palladium(0): Origin and Significance of Divergent Mechanisms. J Am Chem Soc 2024; 146:19249-19260. [PMID: 38959060 DOI: 10.1021/jacs.4c04496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
Two limiting mechanisms are possible for oxidative addition of (hetero)aryl (pseudo)halides at Pd(0): a 3-centered concerted and a nucleophilic displacement mechanism. Until now, there has been little understanding about when each mechanism is relevant. Prior investigations to distinguish between these pathways were limited to a few specific combinations of the substrate and ligand. Here, we computationally evaluated over 180 transition structures for oxidative addition in order to determine mechanistic trends based on substrate, ligand(s), and coordination number. Natural abundance 13C kinetic isotope effects provide experimental results consistent with computational predictions. Key findings include that (1) differences in highest occupied molecular orbital (HOMO) symmetries dictate that, although 12e- PdL is strongly biased toward a 3-centered concerted mechanism, 14e- PdL2 often prefers a nucleophilic displacement mechanism; (2) ligand electronics and sterics, including ligand bite angle, influence the preferred mechanism of the reaction at PdL2; (3) phenyl triflate always reacts through a displacement mechanism regardless of the catalyst structure due to the stability of a triflate anion and the inability of oxygen to effectively donate electron density to Pd; and (4) the high reactivity of C-X bonds adjacent to nitrogen in pyridine substrates relates to stereoelectronic stabilization of a nucleophilic displacement transition state. This work has implications for controlling rate and selectivity in catalytic couplings, and we demonstrate application of the mechanistic insight toward chemodivergent cross-couplings of bromochloroheteroarenes.
Collapse
Affiliation(s)
- Matthew J Kania
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Albert Reyes
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Sharon R Neufeldt
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| |
Collapse
|
4
|
Nyagilo VO, Mallojjala SC, Hirschi JS. Transition State Analysis of Key Steps in Dual Photoredox-Cobalt-Catalyzed Elimination of Alkyl Bromides. ACS Catal 2024; 14:4683-4689. [PMID: 39211423 PMCID: PMC11361288 DOI: 10.1021/acscatal.3c06324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
A combination of inter- and intramolecular 13C kinetic isotope effects and density functional theory analysis is used to evaluate the key mechanistic events of sequentially operating catalytic cycles in the dual photoredox-cobalt-catalyzed elimination of alkyl bromides. The results point to a mechanism proceeding via irreversible halogen-atom transfer (XAT) from the alkyl halide, resulting in an alkyl radical, which undergoes hydrogen-atom transfer (HAT) to a Co(II) intermediate to deliver the product olefin. Alternative pathways involving nucleophilic substitution by a Co(I) species and by β-hydride elimination are discounted based on the poor agreement of experimental and predicted 13C KIEs. This mechanistic understanding is used to evaluate the origins of regioselectivity in the elimination step for an unsymmetrical alkyl halide catalyzed by electronically and sterically distinct cobaloxime catalysts. This study represents the experimental validation of the key features of the transition state structure of XAT by α-aminoalkyl radicals, an important class of atom transfer reactions that generate carbon-centered radicals from alkyl and aryl halides. Furthermore, it illustrates the power of 13C KIEs in probing complex mechanisms in metallaphotoredox catalysis.
Collapse
Affiliation(s)
- Victor O Nyagilo
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| | | | - Jennifer S Hirschi
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| |
Collapse
|
5
|
Colin-Molina A, Nematiaram T, Cheung AMH, Troisi A, Frisbie CD. The Conductance Isotope Effect in Oligophenylene Imine Molecular Wires Depends on the Number and Spacing of 13C-Labeled Phenylene Rings. ACS NANO 2024; 18:7444-7454. [PMID: 38411123 DOI: 10.1021/acsnano.3c11327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
We report a strong and structurally sensitive 13C intramolecular conductance isotope effect (CIE) for oligophenyleneimine (OPI) molecular wires connected to Au electrodes. Wires were built from Au surfaces beginning with the formation of 4-aminothiophenol self-assembled monolayers (SAMs) followed by subsequent condensation reactions with 13C-labeled terephthalaldehyde and phenylenediamine; in these monomers the phenylene rings were either completely 13C-labeled or the naturally abundant 12C isotopologues. Alternatively, perdeuterated versions of terephthalaldehyde and phenylenediamine were employed to make 2H(D)-labeled OPI wires. For 13C-isotopologues of short OPI wires (<4 nm) in length where the charge transport mechanism is tunneling, there was no measurable effect, i.e., 13C CIE ≈ 1, where CIE is defined as the ratio of labeled and unlabeled wire resistances, i.e., CIE = Rheavy/Rlight. However, for long OPI wires >4 nm, in which the transport mechanism is polaron hopping, a strong 13C CIE = 4-5 was observed. A much weaker inverse CIE < 1 was evident for the longest D-labeled wires. Importantly, the magnitude of the 13C CIE was sensitive to the number and spacing of 13C-labeled rings, i.e., the CIE was structurally sensitive. The structural sensitivity is intriguing because it may be employed to understand polaron hopping mechanisms and charge localization/delocalization in molecular wires. A preliminary theoretical analysis explored several possible explanations for the CIE, but so far a fully satisfactory explanation has not been identified. Nevertheless, the latest results unambiguously demonstrate structural sensitivity of the heavy atom CIE, offering directions for further utilization of this interesting effect.
Collapse
Affiliation(s)
- Abraham Colin-Molina
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Tahereh Nematiaram
- Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G11XL, United Kingdom
| | - Andy Man Hong Cheung
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Alessandro Troisi
- Department of Chemistry, University of Liverpool, Liverpool L697ZD, United Kingdom
| | - C Daniel Frisbie
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| |
Collapse
|
6
|
Abstract
Stable isotopes such as 2H, 13C, and 15N have important applications in chemistry and drug discovery. Late-stage incorporation of uncommon isotopes via isotopic exchange allows for the direct conversion of complex molecules into their valuable isotopologues without requiring a de novo synthesis. While synthetic methods exist for the conversion of hydrogen and carbon atoms into their less abundant isotopes, a corresponding method for accessing 15N-primary amines from their naturally occurring 14N-analogues has not yet been disclosed. We report an approach to access 15N-labeled primary amines via late-stage isotopic exchange using a simple benzophenone imine as the 15N source. By activating α-1 and α-2° amines to Katritzky pyridinium salts and α-3° amines to redox-active imines, we can engage primary alkyl amines in a deaminative amination. The redox-active imines proceed via a radical-polar crossover mechanism, whereas the Katritzky salts are engaged in copper catalysis via an electron donor-acceptor complex. The method is general for a variety of amines, including multiple drug compounds, and results in complete and selective isotopic labeling.
Collapse
Affiliation(s)
- Julia R Dorsheimer
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Tomislav Rovis
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| |
Collapse
|
7
|
Barecka MH, Kovalev MK, Muhamad MZ, Ren H, Ager JW, Lapkin AA. CO 2 electroreduction favors carbon isotope 12C over 13C and facilitates isotope separation. iScience 2023; 26:107834. [PMID: 37954138 PMCID: PMC10638474 DOI: 10.1016/j.isci.2023.107834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 07/24/2023] [Accepted: 09/01/2023] [Indexed: 11/14/2023] Open
Abstract
We discovered that CO2 electroreduction strongly favors the conversion of the dominant isotope of carbon (12C) and discriminates against the less abundant, stable carbon 13C isotope. Both absorption of CO2 in the alkaline electrolyte and CO2 electrochemical reduction favor the lighter isotopologue. As a result, the stream of unreacted CO2 leaving the electrolyzer has an increased 13C content, and the depletion of 13C in the product is several times greater than that of photosynthesis. Using a natural abundance feed, we demonstrate enriching of the 13C fraction to ∼1.3% (i.e., +18%) in a single-pass reactor and propose a scalable and economically attractive process to yield isotopes of a commercial purity. Our finding opens pathways to both cheaper and less energy-intensive production of stable isotopes (13C, 15N) essential to the healthcare and chemistry research, and to an economically viable, disruptive application of electrolysis technologies developed in the context of sustainability transition.
Collapse
Affiliation(s)
- Magda H. Barecka
- Department of Chemical Engineering, Northeastern University, 360 Huntington Avenue, Boston, MA 02215, USA
- Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Avenue, Boston, MA 02215, USA
- Cambridge Centre for Advanced Research and Education in Singapore, CARES Ltd. 1 CREATE Way, CREATE Tower #05-05, Singapore 138602, Singapore
| | - Mikhail K. Kovalev
- Cambridge Centre for Advanced Research and Education in Singapore, CARES Ltd. 1 CREATE Way, CREATE Tower #05-05, Singapore 138602, Singapore
| | - Marsha Zakir Muhamad
- Cambridge Centre for Advanced Research and Education in Singapore, CARES Ltd. 1 CREATE Way, CREATE Tower #05-05, Singapore 138602, Singapore
| | - Hangjuan Ren
- Cambridge Centre for Advanced Research and Education in Singapore, CARES Ltd. 1 CREATE Way, CREATE Tower #05-05, Singapore 138602, Singapore
- Department of Chemistry, University of Oxford, Oxford OX1 3QR, UK
| | - Joel W. Ager
- Berkeley Educational Alliance for Research in Singapore (BEARS), Ltd, 1 CREATE Way, Singapore 138602, Singapore
- Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, CA 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Alexei A. Lapkin
- Cambridge Centre for Advanced Research and Education in Singapore, CARES Ltd. 1 CREATE Way, CREATE Tower #05-05, Singapore 138602, Singapore
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| |
Collapse
|
8
|
Reisenbauer J, Finkelstein P, Ebert MO, Morandi B. Mechanistic Investigation of the Nickel-Catalyzed Transfer Hydrocyanation of Alkynes. ACS Catal 2023; 13:11548-11555. [PMID: 37671177 PMCID: PMC10476158 DOI: 10.1021/acscatal.3c02977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 07/28/2023] [Indexed: 09/07/2023]
Abstract
The implementation of HCN-free transfer hydrocyanation reactions on laboratory scales has recently been achieved by using HCN donor reagents under nickel- and Lewis acid co-catalysis. More recently, malononitrile-based HCN donor reagents were shown to undergo the C(sp3)-CN bond activation by the nickel catalyst in the absence of Lewis acids. However, there is a lack of detailed mechanistic understanding of the challenging C(sp3)-CN bond cleavage step. In this work, in-depth kinetic and computational studies using alkynes as substrates were used to elucidate the overall reaction mechanism of this transfer hydrocyanation, with a particular focus on the activation of the C(sp3)-CN bond to generate the active H-Ni-CN transfer hydrocyanation catalyst. Comparisons of experimentally and computationally derived 13C kinetic isotope effect data support a direct oxidative addition mechanism of the nickel catalyst into the C(sp3)-CN bond facilitated by the coordination of the second nitrile group to the nickel catalyst.
Collapse
Affiliation(s)
| | | | | | - Bill Morandi
- ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland
| |
Collapse
|
9
|
Dale HA, Hodges GR, Lloyd-Jones GC. Kinetics and Mechanism of Azole n-π*-Catalyzed Amine Acylation. J Am Chem Soc 2023; 145:18126-18140. [PMID: 37526380 PMCID: PMC10436283 DOI: 10.1021/jacs.3c06258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Indexed: 08/02/2023]
Abstract
Azole anions are highly competent in the activation of weak acyl donors, but, unlike neutral (aprotic) Lewis bases, are not yet widely applied as acylation catalysts. Using a combination of in situ and stopped-flow 1H/19F NMR spectroscopy, kinetics, isotopic labeling, 1H DOSY, and electronic structure calculations, we have investigated azole-catalyzed aminolysis of p-fluorophenyl acetate. The global kinetics have been elucidated under four sets of conditions, and the key elementary steps underpinning catalysis deconvoluted using a range of intermediates and transition state probes. While all evidence points to an overarching mechanism involving n-π* catalysis via N-acylated azole intermediates, a diverse array of kinetic regimes emerges from this framework. Even seemingly minor changes to the solvent, auxiliary base, or azole catalyst can elicit profound changes in the temporal evolution, thermal sensitivity, and progressive inhibition of catalysis. These observations can only be rationalized by taking a holistic view of the mechanism and a set of limiting regimes for the kinetics. Overall, the analysis of 18 azole catalysts spanning nearly 10 orders of magnitude in acidity highlights the pitfall of pursuing ever more nucleophilic catalysts without regard for catalyst speciation.
Collapse
Affiliation(s)
- Harvey
J. A. Dale
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K.
| | - George R. Hodges
- Jealott’s
Hill International Research Centre, Syngenta, Bracknell, Berkshire RG42 6EY, U.K.
| | - Guy C. Lloyd-Jones
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K.
| |
Collapse
|
10
|
Leitner BP, Lee WD, Zhu W, Zhang X, Gaspar RC, Li Z, Rabinowitz JD, Perry RJ. Tissue-specific reprogramming of glutamine metabolism maintains tolerance to sepsis. PLoS One 2023; 18:e0286525. [PMID: 37410734 PMCID: PMC10325078 DOI: 10.1371/journal.pone.0286525] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 05/17/2023] [Indexed: 07/08/2023] Open
Abstract
Reprogramming metabolism is of great therapeutic interest for reducing morbidity and mortality during sepsis-induced critical illness. Disappointing results from randomized controlled trials targeting glutamine and antioxidant metabolism in patients with sepsis have begged a deeper understanding of the tissue-specific metabolic response to sepsis. The current study sought to fill this gap. We analyzed skeletal muscle transcriptomics of critically ill patients, versus elective surgical controls, which revealed reduced expression of genes involved in mitochondrial metabolism and electron transport, with increases in glutathione cycling, glutamine, branched chain, and aromatic amino acid transport. We then performed untargeted metabolomics and 13C isotope tracing to analyze systemic and tissue specific metabolic phenotyping in a murine polymicrobial sepsis model. We found an increased number of correlations between the metabolomes of liver, kidney, and spleen, with loss of correlations between the heart and quadriceps and all other organs, pointing to a shared metabolic signature within vital abdominal organs, and unique metabolic signatures for muscles during sepsis. A lowered GSH:GSSG and elevated AMP:ATP ratio in the liver underlie the significant upregulation of isotopically labeled glutamine's contribution to TCA cycle anaplerosis and glutamine-derived glutathione biosynthesis; meanwhile, the skeletal muscle and spleen were the only organs where glutamine's contribution to the TCA cycle was significantly suppressed. These results highlight tissue-specific mitochondrial reprogramming to support liver energetic demands and antioxidant synthesis, rather than global mitochondrial dysfunction, as a metabolic consequence of sepsis.
Collapse
Affiliation(s)
- Brooks P. Leitner
- Department of Cellular & Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
- Department of Internal Medicine, Yale University, New Haven, Connecticut, United States of America
| | - Won D. Lee
- Lewis Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
- Department of Chemistry, Princeton University, Princeton, New Jersey, United States of America
| | - Wanling Zhu
- Department of Cellular & Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
- Department of Internal Medicine, Yale University, New Haven, Connecticut, United States of America
| | - Xinyi Zhang
- Department of Cellular & Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
- Department of Internal Medicine, Yale University, New Haven, Connecticut, United States of America
| | - Rafael C. Gaspar
- Department of Cellular & Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
- Department of Internal Medicine, Yale University, New Haven, Connecticut, United States of America
| | - Zongyu Li
- Department of Cellular & Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
- Department of Internal Medicine, Yale University, New Haven, Connecticut, United States of America
| | - Joshua D. Rabinowitz
- Lewis Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
- Department of Chemistry, Princeton University, Princeton, New Jersey, United States of America
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- Ludwig Institute for Cancer Research, Princeton Branch, Princeton, New Jersey, United States of America
| | - Rachel J. Perry
- Department of Cellular & Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
- Department of Internal Medicine, Yale University, New Haven, Connecticut, United States of America
| |
Collapse
|
11
|
Xia X, Gao Y. Determining Reaction Paths by Evaluating Kinetic Isotopic Effects with Density Functional Theory: Example of Methane Thermogenesis. J Chem Inf Model 2023; 63:2742-2747. [PMID: 37094567 DOI: 10.1021/acs.jcim.3c00531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023]
Abstract
This study demonstrates the determination of reaction pathways by evaluating the carbon kinetic isotopic effect and interpreting isotopic fractionations based on quantum chemical calculations. The reaction under investigation is methane thermogenesis from the decomposition of kerogen, which is a geochemical reaction under temperatures below 150 °C and lasts for tens of millions of years. Investigating its mechanism requires theoretical simulations because lab experiments at practical time-lengths require elevated temperatures, which introduce unwanted side reactions. Density functional theory and kinetic simulations were conducted on isotopic fractionations with the use of two possible pathways (free-radical versus carbonium), and the results were compared to field data sets. Different molecular sizes of kerogen were investigated to account for the hindrance of translation and rotation in modeling a reactant in the solid phase. Both pathways have low reaction barriers, implying that the reaction rates are limited by the concentration of active species (hydrated protons and free radicals). The results support the carbonium pathway and rule out the free-radical pathway as the 13CH4 from the latter would be 30‰ more depleted than the observed data. Additionally, simulations were conducted on hydrocarbon isotope fractionation of the carbonium pathway with consideration of hydrogen exchange between methane and water, successively reproducing the observed abundances of deuterium-containing isotopologues (13CH3D, 13CH3D, and 12CH2D2).
Collapse
Affiliation(s)
- Xinyu Xia
- Department of Earth and Planetary Sciences, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Yongli Gao
- Department of Earth and Planetary Sciences, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| |
Collapse
|
12
|
Lovi JM, Sen S. Effects of the 10B/ 11B isotopic substitution on shear relaxation in supercooled B 2O 3 liquid: A validation of the elastic model of viscous flow. J Chem Phys 2023; 158:141103. [PMID: 37061470 DOI: 10.1063/5.0147333] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023] Open
Abstract
The effects of atomic mass in terms of its zero-point vibrational energy, on molar volume, glass transition temperature Tg, and viscosity are studied in glassy and supercooled B2O3 liquids using boron isotope substitutions. The molar volume decreases and Tg and isothermal viscosity increase on the substitution of lighter 10B isotopes with the heavier 11B isotopes. These effects are argued to be a manifestation of the higher zero-point vibrational energy of the lighter isotope, which along with the anharmonicity of the potential well, results in a longer equilibrium inter-atomic distance and larger mean-square displacement with respect to that for the heavier isotope. The isotope effect on viscosity is increasingly enhanced as the temperature approaches Tg, which is shown to be consistent with the prediction of the elastic models of viscous flow and shear relaxation.
Collapse
Affiliation(s)
- Jacob M Lovi
- Department of Materials Science and Engineering, University of California at Davis, Davis, California 95616, USA
| | - Sabyasachi Sen
- Department of Materials Science and Engineering, University of California at Davis, Davis, California 95616, USA
| |
Collapse
|
13
|
Chen BW. Equilibrium and kinetic isotope effects in heterogeneous catalysis: A density functional theory perspective. CATAL COMMUN 2023. [DOI: 10.1016/j.catcom.2023.106654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023] Open
|
14
|
Bocus M, Goeminne R, Lamaire A, Cools-Ceuppens M, Verstraelen T, Van Speybroeck V. Nuclear quantum effects on zeolite proton hopping kinetics explored with machine learning potentials and path integral molecular dynamics. Nat Commun 2023; 14:1008. [PMID: 36823162 PMCID: PMC9950054 DOI: 10.1038/s41467-023-36666-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 02/10/2023] [Indexed: 02/25/2023] Open
Abstract
Proton hopping is a key reactive process within zeolite catalysis. However, the accurate determination of its kinetics poses major challenges both for theoreticians and experimentalists. Nuclear quantum effects (NQEs) are known to influence the structure and dynamics of protons, but their rigorous inclusion through the path integral molecular dynamics (PIMD) formalism was so far beyond reach for zeolite catalyzed processes due to the excessive computational cost of evaluating all forces and energies at the Density Functional Theory (DFT) level. Herein, we overcome this limitation by training first a reactive machine learning potential (MLP) that can reproduce with high fidelity the DFT potential energy surface of proton hopping around the first Al coordination sphere in the H-CHA zeolite. The MLP offers an immense computational speedup, enabling us to derive accurate reaction kinetics beyond standard transition state theory for the proton hopping reaction. Overall, more than 0.6 μs of simulation time was needed, which is far beyond reach of any standard DFT approach. NQEs are found to significantly impact the proton hopping kinetics up to ~473 K. Moreover, PIMD simulations with deuterium can be performed without any additional training to compute kinetic isotope effects over a broad range of temperatures.
Collapse
Affiliation(s)
- Massimo Bocus
- Center for Molecular Modeling, Ghent University, Technologiepark 46, 9052, Zwijnaarde, Belgium
| | - Ruben Goeminne
- Center for Molecular Modeling, Ghent University, Technologiepark 46, 9052, Zwijnaarde, Belgium
| | - Aran Lamaire
- Center for Molecular Modeling, Ghent University, Technologiepark 46, 9052, Zwijnaarde, Belgium
| | - Maarten Cools-Ceuppens
- Center for Molecular Modeling, Ghent University, Technologiepark 46, 9052, Zwijnaarde, Belgium
| | - Toon Verstraelen
- Center for Molecular Modeling, Ghent University, Technologiepark 46, 9052, Zwijnaarde, Belgium
| | | |
Collapse
|
15
|
Somprasong S, Reis MC, Harutyunyan SR. Catalytic Access to Chiral δ-Lactams via Nucleophilic Dearomatization of Pyridine Derivatives. Angew Chem Int Ed Engl 2023; 62:e202217328. [PMID: 36522289 DOI: 10.1002/anie.202217328] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 12/12/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022]
Abstract
Nitrogen-bearing rings are common features in the molecular structures of modern drugs, with chiral δ-lactams being an important subclass due to their known pharmacological properties. Catalytic dearomatization of preactivated pyridinium ion derivatives emerged as a powerful method for the rapid construction of chiral N-heterocycles. However, direct catalytic dearomatization of simple pyridine derivatives are scarce and methodologies yielding chiral δ-lactams are yet to be developed. Herein, we describe an enantioselective C4-dearomatization of methoxypyridine derivatives for the preparation of functionalised enantioenriched δ-lactams using chiral copper catalysis. Experimental 13 C kinetic isotope effects and density functional theory calculations shed light on the reaction mechanism and the origin of enantioselectivity.
Collapse
Affiliation(s)
- Siriphong Somprasong
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Marta Castiñeira Reis
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Syuzanna R Harutyunyan
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| |
Collapse
|
16
|
Kee CW. Molecular Understanding and Practical In Silico Catalyst Design in Computational Organocatalysis and Phase Transfer Catalysis-Challenges and Opportunities. Molecules 2023; 28:1715. [PMID: 36838703 PMCID: PMC9966076 DOI: 10.3390/molecules28041715] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/03/2023] [Accepted: 02/05/2023] [Indexed: 02/25/2023] Open
Abstract
Through the lens of organocatalysis and phase transfer catalysis, we will examine the key components to calculate or predict catalysis-performance metrics, such as turnover frequency and measurement of stereoselectivity, via computational chemistry. The state-of-the-art tools available to calculate potential energy and, consequently, free energy, together with their caveats, will be discussed via examples from the literature. Through various examples from organocatalysis and phase transfer catalysis, we will highlight the challenges related to the mechanism, transition state theory, and solvation involved in translating calculated barriers to the turnover frequency or a metric of stereoselectivity. Examples in the literature that validated their theoretical models will be showcased. Lastly, the relevance and opportunity afforded by machine learning will be discussed.
Collapse
Affiliation(s)
- Choon Wee Kee
- Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), 1 Pesek Road, Jurong Island, Singapore 627833, Republic of Singapore
| |
Collapse
|
17
|
Ma Z, Yan Z, Li X, Chung LW. Quantum Tunneling in Reactions Modulated by External Electric Fields: Reactivity and Selectivity. J Phys Chem Lett 2023; 14:1124-1132. [PMID: 36705472 DOI: 10.1021/acs.jpclett.2c03461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Quantum tunneling and external electric fields (EEFs) can promote some reactions. However, the synergetic effect of an EEF on a tunneling-involving reaction and its temperature-dependence is not very clear. In this study, we extensively investigated how EEFs affect three reactions that involve hydrogen- or (ground- and excited-state) carbon-tunneling using reliable DFT, DLPNO-CCSD(T1), and variational transition-state theory methods. Our study revealed that oriented EEFs can significantly reduce the barrier and corresponding barrier width (and vice versa) through more electrostatic stabilization in transition states. These EEF effects enhance the nontunneling and tunneling-involving rates. Such EEF effects also decrease the crossover temperatures and quantum tunneling contribution, albeit with lower and thinner barriers. Moreover, EEFs can modulate and switch on/off the tunneling-driven 1,2-H migration of hydroxycarbenes under cryogenic conditions. Furthermore, our study predicts for the first time that EEF/tunneling synergy can control the chemo- or site-selectivity of one molecule bearing two similar/same reactive sites.
Collapse
Affiliation(s)
- Zhifeng Ma
- Shenzhen Grubbs Institute, Department of Chemistry, and Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, 1088 Xueyuan Avenue, Shenzhen 518055, P. R. China
| | - Zeyin Yan
- Shenzhen Grubbs Institute, Department of Chemistry, and Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, 1088 Xueyuan Avenue, Shenzhen 518055, P. R. China
| | - Xin Li
- Shenzhen Grubbs Institute, Department of Chemistry, and Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, 1088 Xueyuan Avenue, Shenzhen 518055, P. R. China
| | - Lung Wa Chung
- Shenzhen Grubbs Institute, Department of Chemistry, and Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, 1088 Xueyuan Avenue, Shenzhen 518055, P. R. China
| |
Collapse
|
18
|
Mallojjala SC, Nyagilo VO, Corio SA, Adili A, Dagar A, Loyer KA, Seidel D, Hirschi JS. Probing the Free Energy Landscape of Organophotoredox-Catalyzed Anti-Markovnikov Hydrofunctionalization of Alkenes. J Am Chem Soc 2022; 144:17692-17699. [PMID: 36112933 DOI: 10.1021/jacs.2c07807] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Experimental 13C kinetic isotope effects (KIEs) provide unprecedented mechanistic insight into three intermolecular anti-Markovnikov alkene hydrofunctionalization reactions─hydroesterification, hydroamination, and hydroetherification─enabled by organophotoredox catalysis. All three reactions are found to proceed via initial oxidation of the model alkenes to form a radical cation intermediate, followed by sequential nucleophilic attack and hydrogen-atom transfer to deliver the hydrofunctionalized product. A normal 13C KIE on the olefinic carbon that undergoes nucleophilic attack provides qualitative evidence for rate-limiting nucleophilic attack in all three reactions. Comparison to predicted 13C KIE values obtained from density functional theory (DFT) calculations for this step reveals that alkene oxidation has partial rate-limiting influence in hydroesterification and hydroamination, while the nucleophilic attack is solely rate-limiting in the hydroetherification reaction. The basic additive (2,6-lutidine) activates the nucleophile via deprotonation and is an integral part of the transition state for nucleophilic attack on the radical cation, providing an important design principle for the development of asymmetric versions of these reactions. A more electron-rich pyridine base (2,6-dimethoxypyridine) exhibits considerable rate enhancements in both inter- and intramolecular hydrofunctionalization reactions.
Collapse
Affiliation(s)
| | - Victor O. Nyagilo
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| | - Stephanie A. Corio
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| | - Alafate Adili
- Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Anuradha Dagar
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| | - Kimberly A. Loyer
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| | - Daniel Seidel
- Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Jennifer S. Hirschi
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| |
Collapse
|
19
|
Chandra Mallojjala S, Sarkar R, Karugu RW, Manna MS, Ray S, Mukherjee S, Hirschi JS. Mechanism and Origin of Remote Stereocontrol in the Organocatalytic Enantioselective Formal C(sp 2)–H Alkylation Using Nitroalkanes as Alkylating Agents. J Am Chem Soc 2022; 144:17399-17406. [PMID: 36108139 DOI: 10.1021/jacs.2c02941] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Experimental 13C kinetic isotope effects (KIEs) and density functional theory (DFT) calculations are used to evaluate the mechanism and origin of enantioselectivity in the formal C(sp2)-H alkylative desymmetrization of cyclopentene-1,3-diones using nitroalkanes as the alkylating agent. An unusual combination of an inverse (∼0.980) and a normal (∼1.033) KIE is observed on the bond-forming carbon atoms of the cyclopentene-1,3-dione and nitroalkane, respectively. These data provide strong support for a mechanism involving reversible carbon-carbon bond formation followed by rate- and enantioselectivity-determining nitro group elimination. The theoretical free-energy profile and the predicted KIEs indicate that this elimination event occurs via an E1cB pathway. The origin of remote stereocontrol is evaluated by distortion-interaction and SAPT0 analyses of the E1cB transition states leading to both enantiomers.
Collapse
Affiliation(s)
| | - Rahul Sarkar
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - Rachael W. Karugu
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| | - Madhu Sudan Manna
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - Sayan Ray
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - Santanu Mukherjee
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - Jennifer S. Hirschi
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| |
Collapse
|
20
|
García-Domínguez A, Leach AG, Lloyd-Jones GC. In Situ Studies of Arylboronic Acids/Esters and R 3SiCF 3 Reagents: Kinetics, Speciation, and Dysfunction at the Carbanion-Ate Interface. Acc Chem Res 2022; 55:1324-1336. [PMID: 35435655 PMCID: PMC9069690 DOI: 10.1021/acs.accounts.2c00113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Reagent instability reduces the efficiency of chemical processes, and while much effort is devoted to reaction optimization, less attention is paid to the mechanistic causes of reagent decomposition. Indeed, the response is often to simply use an excess of the reagent. Two reaction classes with ubiquitous examples of this are the Suzuki-Miyaura cross-coupling of boronic acids/esters and the transfer of CF3 or CF2 from the Ruppert-Prakash reagent, TMSCF3. This Account describes some of the overarching features of our mechanistic investigations into their decomposition. In the first section we summarize how specific examples of (hetero)arylboronic acids can decompose via aqueous protodeboronation processes: Ar-B(OH)2 + H2O → ArH + B(OH)3. Key to the analysis was the development of a kinetic model in which pH controls boron speciation and heterocycle protonation states. This method revealed six different protodeboronation pathways, including self-catalysis when the pH is close to the pKa of the boronic acid, and protodeboronation via a transient aryl anionoid pathway for highly electron-deficient arenes. The degree of "protection" of boronic acids by diol-esterification is shown to be very dependent on the diol identity, with six-membered ring esters resulting in faster protodeboronation than the parent boronic acid. In the second section of the Account we describe 19F NMR spectroscopic analysis of the kinetics of the reaction of TMSCF3 with ketones, fluoroarenes, and alkenes. Processes initiated by substoichiometric "TBAT" ([Ph3SiF2][Bu4N]) involve anionic chain reactions in which low concentrations of [CF3]- are rapidly and reversibly liberated from a siliconate reservoir, [TMS(CF3)2][Bu4N]. Increased TMSCF3 concentrations reduce the [CF3]- concentration and thus inhibit the rates of CF3 transfer. Computation and kinetics reveal that the TMSCF3 intermolecularly abstracts fluoride from [CF3]- to generate the CF2, in what would otherwise be an endergonic α-fluoride elimination. Starting from [CF3]- and CF2, a cascade involving perfluoroalkene homologation results in the generation of a hindered perfluorocarbanion, [C11F23]-, and inhibition. The generation of CF2 from TMSCF3 is much more efficiently mediated by NaI, and in contrast to TBAT, the process undergoes autoacceleration. The process involves NaI-mediated α-fluoride elimination from [CF3][Na] to generate CF2 and a [NaI·NaF] chain carrier. Chain-branching, by [(CF2)3I][Na] generated in situ (CF2 + TFE + NaI), causes autoacceleration. Alkenes that efficiently capture CF2 attenuate the chain-branching, suppress autoacceleration, and lead to less rapid difluorocyclopropanation. The Account also highlights how a collaborative approach to experiment and computation enables mechanistic insight for control of processes.
Collapse
Affiliation(s)
- Andrés García-Domínguez
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K
| | - Andrew G. Leach
- School of Health Sciences, Stopford Building, The University of Manchester, 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
| |
Collapse
|
21
|
Ben-Tal Y, Boaler PJ, Dale HJA, Dooley RE, Fohn NA, Gao Y, García-Domínguez A, Grant KM, Hall AMR, Hayes HLD, Kucharski MM, Wei R, Lloyd-Jones GC. Mechanistic analysis by NMR spectroscopy: A users guide. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2022; 129:28-106. [PMID: 35292133 DOI: 10.1016/j.pnmrs.2022.01.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 06/14/2023]
Abstract
A 'principles and practice' tutorial-style review of the application of solution-phase NMR in the analysis of the mechanisms of homogeneous organic and organometallic reactions and processes. This review of 345 references summarises why solution-phase NMR spectroscopy is uniquely effective in such studies, allowing non-destructive, quantitative analysis of a wide range of nuclei common to organic and organometallic reactions, providing exquisite structural detail, and using instrumentation that is routinely available in most chemistry research facilities. The review is in two parts. The first comprises an introduction to general techniques and equipment, and guidelines for their selection and application. Topics include practical aspects of the reaction itself, reaction monitoring techniques, NMR data acquisition and processing, analysis of temporal concentration data, NMR titrations, DOSY, and the use of isotopes. The second part comprises a series of 15 Case Studies, each selected to illustrate specific techniques and approaches discussed in the first part, including in situ NMR (1/2H, 10/11B, 13C, 15N, 19F, 29Si, 31P), kinetic and equilibrium isotope effects, isotope entrainment, isotope shifts, isotopes at natural abundance, scalar coupling, kinetic analysis (VTNA, RPKA, simulation, steady-state), stopped-flow NMR, flow NMR, rapid injection NMR, pure shift NMR, dynamic nuclear polarisation, 1H/19F DOSY NMR, and in situ illumination NMR.
Collapse
Affiliation(s)
- Yael Ben-Tal
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Patrick J Boaler
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Harvey J A Dale
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Ruth E Dooley
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom; Evotec (UK) Ltd, 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire OX14 4RZ, United Kingdom
| | - Nicole A Fohn
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Yuan Gao
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Andrés García-Domínguez
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Katie M Grant
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Andrew M R Hall
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Hannah L D Hayes
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Maciej M Kucharski
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Ran Wei
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Guy C Lloyd-Jones
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom.
| |
Collapse
|
22
|
Joshi C, Macharia JM, Izzo JA, Wambua V, Kim S, Hirschi JS, Vetticatt MJ. Isotope Effects Reveal the Catalytic Mechanism of the Archetypical Suzuki-Miyaura Reaction. ACS Catal 2022; 12:2959-2966. [PMID: 37168650 PMCID: PMC10168682 DOI: 10.1021/acscatal.1c05802] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Experimental and theoretical 13C kinetic isotope effects (KIEs) are utilized to obtain atomistic insight into the catalytic mechanism of the Pd(PPh3)4-catalyzed Suzuki-Miyaura reaction of aryl halides and aryl boronic acids. Under catalytic conditions, we establish that oxidative addition of aryl bromides occurs to a 12-electron monoligated palladium complex (Pd-(PPh3)). This is based on the congruence of the experimental KIE for the carbon attached to bromine (KIEC-Br = 1.020) and predicted KIEC-Br for the transition state for oxidative addition to the Pd(PPh3) complex (1.021). For aryl iodides, the near-unity KIEC-I of ~1.003 suggests that the first irreversible step in the catalytic cycle precedes oxidative addition and is likely the binding of the iodoarene to Pd(PPh3). Our results suggest that the commonly proposed oxidative addition to the 14-electron Pd(PPh3)2 complex can occur only in the presence of excess added ligand or under stoichiometric conditions; in both cases, experimental KIEC-Br of 1.031 is measured, which is identical to the predicted KIEC-Br for the transition state for oxidative addition to the Pd(PPh3)2 complex (1.031). The transmetalation step, under catalytic conditions, is shown to proceed via a tetracoordinate boronate (8B4) intermediate with a Pd-O-B linkage based on the agreement between an experimental KIE for the carbon atom involved in transmetalation (KIEC-Boron = 1.035) and a predicted KIEC-Boron for the 8B4 transmetalation transition state (1.034).
Collapse
Affiliation(s)
- Chetan Joshi
- Department of Chemistry, Binghamton University, Vestal, New York 13850, United States
| | - Juliet M. Macharia
- Department of Chemistry, Binghamton University, Vestal, New York 13850, United States
| | - Joseph A. Izzo
- Department of Chemistry, Binghamton University, Vestal, New York 13850, United States
| | - Victor Wambua
- Department of Chemistry, Binghamton University, Vestal, New York 13850, United States
| | - Sungjin Kim
- Department of Chemistry, Binghamton University, Vestal, New York 13850, United States
| | - Jennifer S. Hirschi
- Department of Chemistry, Binghamton University, Vestal, New York 13850, United States
| | - Mathew J. Vetticatt
- Department of Chemistry, Binghamton University, Vestal, New York 13850, United States
| |
Collapse
|