1
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Wheeler JI, Schaefer AJ, Ess DH. Trajectory-Based Time-Resolved Mechanism for Benzene Reductive Elimination from Cyclopentadienyl Mo/W Phenyl Hydride Complexes. J Phys Chem A 2024. [PMID: 38836889 DOI: 10.1021/acs.jpca.4c01788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
Calculated potential energy structures and landscapes are very often used to define the sequence of reaction steps in an organometallic reaction mechanism and interpret kinetic isotope effect (KIE) measurements. Underlying most of this structure-to-mechanism translation is the use of statistical rate theories without consideration of atomic/molecular motion. Here we report direct dynamics simulations for an organometallic benzene reductive elimination reaction, where nonstatistical intermediates and dynamic-controlled pathways were identified. Specifically, we report single spin state as well as mixed spin state quasiclassical direct dynamics trajectories in the gas phase and explicit solvent for benzene reductive elimination from Mo and W bridged cyclopentadienyl phenyl hydride complexes ([Me2Si(C5Me4)2]M(H)(Ph), M = Mo and W). Different from the energy landscape mechanistic sequence, the dynamics trajectories revealed that after the benzene C-H bond forming transition state (often called reductive coupling), σ-coordination and π-coordination intermediates are either skipped or circumvented and that there is a direct pathway to forming a spin flipped solvent caged intermediate, which occurs in just a few hundred femtoseconds. Classical molecular dynamics simulations were then used to estimate the lifetime of the caged intermediate, which is between 200 and 400 picoseconds. This indicates that when the η2-π-coordination intermediate is formed, it occurs only after the first formation of the solvent-caged intermediate. This dynamic mechanism intriguingly suggests the possibility that the solvent-caged intermediate rather than a coordination intermediate is responsible (or partially responsible) for the inverse KIE value experimentally measured for W. Additionally, this dynamic mechanism prompted us to calculate the kH/kD KIE value for the C-H bonding forming transition states of Mo and W. Surprisingly, Mo gave a normal value, while W gave an inverse value, albeit small, due to a much later transition state position.
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Affiliation(s)
- Joshua I Wheeler
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84604, United States
| | - Anthony J Schaefer
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84604, United States
| | - Daniel H Ess
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84604, United States
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2
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Joy J, Schaefer AJ, Teynor MS, Ess DH. Dynamical Origin of Rebound versus Dissociation Selectivity during Fe-Oxo-Mediated C-H Functionalization Reactions. J Am Chem Soc 2024; 146:2452-2464. [PMID: 38241715 DOI: 10.1021/jacs.3c09891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2024]
Abstract
The mechanism of catalytic C-H functionalization of alkanes by Fe-oxo complexes is often suggested to involve a hydrogen atom transfer (HAT) step with the formation of a radical-pair intermediate followed by diverging pathways for radical rebound, dissociation, or desaturation. Recently, we showed that in some Fe-oxo reactions, the radical pair is a nonstatistical-type intermediate and dynamic effects control rebound versus dissociation pathway selectivity. However, the effect of the solvent cage on the stability and lifetime of the radical-pair intermediate has never been analyzed. Moreover, because of the extreme complexity of motion that occurs during dynamics trajectories, the underlying physical origin of pathway selectivity has not yet been determined. For the reaction between [(TQA_Cl)FeIVO]+ and cyclohexane, here, we report explicit solvent trajectories and machine learning analysis on transition-state sampled features (e.g., vibrational, velocity, and geometric) that identified the transferring hydrogen atom kinetic energy as the most important factor controlling rebound versus nonrebound dynamics trajectories, which provides an explanation for our previously proposed dynamic matching effect in fast rebound trajectories that bypass the radical-pair intermediate. Manual control of the reaction trajectories confirmed the importance of this feature and provides a mechanism to enhance or diminish selectivity for the rebound pathway. This led to a general catalyst design principle and proof-of-principle catalyst design that showcases how to control rebound versus dissociation reaction pathway selectivity.
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Affiliation(s)
- Jyothish Joy
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84604, United States
| | - Anthony J Schaefer
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84604, United States
| | - Matthew S Teynor
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84604, United States
| | - Daniel H Ess
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84604, United States
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3
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Pu M, Nielsen CDT, Senol E, Sperger T, Schoenebeck F. Post-Transition-State Dynamic Effects in the Transmetalation of Pd(II)-F to Pd(II)-CF 3. JACS AU 2024; 4:263-275. [PMID: 38274253 PMCID: PMC10806791 DOI: 10.1021/jacsau.3c00724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 12/11/2023] [Accepted: 12/12/2023] [Indexed: 01/27/2024]
Abstract
The observation of post-transition-state dynamic effects in the context of metal-based transformation is rare. To date, there has been no reported case of a dynamic effect for the widely employed class of palladium-mediated coupling reactions. We performed an experimental and computational study of the trifluoromethylation of Pd(II)F, which is a key step in the Pd(0)/Pd(II)-catalyzed trifluoromethylation of aryl halides or acid fluorides. Our experiments show that the cis/trans speciation of the formed Pd(II)CF3 is highly solvent- and transmetalation reagent-dependent. We employed GFN2-xTB- and B3LYP-D3-based molecular dynamics trajectory calculations (with and without explicit solvation) along with high-level QM calculations and found that depending on the medium, different transmetalation mechanisms appear to be operative. A statistically representative number of Born-Oppenheimer molecular dynamics (MD) simulations suggest that in benzene, a difluorocarbene is generated in the transmetalation with R3SiCF3, which subsequently recombines with the Pd via two distinct pathways, leading to either the cis- or trans-Pd(II)CF3. Conversely, GFN2-xTB simulations in MeCN suggest that in polar/coordinating solvents an ion-pair mechanism is dominant. A CF3 anion is initially liberated and then rebinds with the Pd(II) cation to give a cis- or trans-Pd(II). In both scenarios, a single transmetalation transition state gives rise to both cis- and trans-species directly, owing to bifurcation after the transition state. The potential subsequent cis- to trans isomerization of the Pd(II)CF3 was also studied and found to be strongly inhibited by free phosphine, which in turn was experimentally identified to be liberated through displacement by a polar/coordinating solvent from the cis-Pd(II)CF3 complex. The simulations also revealed how the variation of the Pd-coordination sphere results in divergent product selectivities.
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Affiliation(s)
- Maoping Pu
- Institute of Organic Chemistry,
RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | | | - Erdem Senol
- Institute of Organic Chemistry,
RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | - Theresa Sperger
- Institute of Organic Chemistry,
RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | - Franziska Schoenebeck
- Institute of Organic Chemistry,
RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
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4
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Lam CC, Goodman JM. Reaction dynamics as the missing puzzle piece: the origin of selectivity in oxazaborolidinium ion-catalysed reactions. Chem Sci 2023; 14:12355-12365. [PMID: 37969604 PMCID: PMC10631253 DOI: 10.1039/d3sc03009a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 10/18/2023] [Indexed: 11/17/2023] Open
Abstract
The selectivity in a group of oxazaborolidinium ion-catalysed reactions between aldehyde and diazo compounds cannot be explained using transition state theory. VRAI-selectivity, developed to predict the outcome of dynamically controlled reactions, can account for both the chemo- and the stereo-selectivity in these reactions, which are controlled by reaction dynamics. Subtle modifications to the substrate or catalyst substituents alter the potential energy surface, leading to changes in predominant reaction pathways and altering the barriers to the major product when reaction dynamics are considered. In addition, this study suggests an explanation for the mysterious inversion of enantioselectivity resulting from the inclusion of an orthoiPrO group in the catalyst.
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Affiliation(s)
- Ching Ching Lam
- Yusuf Hamied Department of Chemistry, University of Cambridge Lensfield Road Cambridge CB2 1EW UK
| | - Jonathan M Goodman
- Yusuf Hamied Department of Chemistry, University of Cambridge Lensfield Road Cambridge CB2 1EW UK
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5
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Davenport MT, Kirkland JK, Ess DH. Dynamic-dependent selectivity in a bisphosphine iron spin crossover C-H insertion/π-coordination reaction. Chem Sci 2023; 14:9400-9408. [PMID: 37712027 PMCID: PMC10498510 DOI: 10.1039/d3sc02078a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 08/13/2023] [Indexed: 09/16/2023] Open
Abstract
Reaction pathway selectivity is generally controlled by competitive transition states. Organometallic reactions are complicated by the possibility that electronic spin state changes rather than transition states can control the relative rates of pathways, which can be modeled as minimum energy crossing points (MECPs). Here we show that in the reaction between bisphosphine Fe and ethylene involving spin state crossover (singlet and triplet spin states) that neither transition states nor MECPs model pathway selectivity consistent with experiment. Instead, single spin state and mixed spin state quasiclassical trajectories demonstrate nonstatistical intermediates and that C-H insertion versus π-coordination pathway selectivity is determined by the dynamic motion during reactive collisions. This example of dynamic-dependent product outcome provides a new selectivity model for organometallic reactions with spin crossover.
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Affiliation(s)
- Michael T Davenport
- Department of Chemistry and Biochemistry, Brigham Young University Provo Utah USA 84604
| | - Justin K Kirkland
- Department of Chemistry and Biochemistry, Brigham Young University Provo Utah USA 84604
| | - Daniel H Ess
- Department of Chemistry and Biochemistry, Brigham Young University Provo Utah USA 84604
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6
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Arepalli N, Mondal S, Chakraborty D, Chattaraj PK. Impact of Static-Oriented Electric Fields on the Kinetics of Some Representative Suzuki-Miyaura and Metal-Cluster Mediated Reactions. Molecules 2023; 28:6169. [PMID: 37630421 PMCID: PMC10459314 DOI: 10.3390/molecules28166169] [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: 06/07/2023] [Revised: 08/13/2023] [Accepted: 08/18/2023] [Indexed: 08/27/2023] Open
Abstract
In order to examine the effect of oriented (static) electric fields (OEF) on the kinetics of some representative Suzuki-Miyaura and metal-cluster mediated reactions at ambient temperatures, density functional theory-based calculations are reported herein. Results indicate that, in general, OEF can facilitate the kinetics of the concerned reactions when applied along the suitable direction (parallel or anti-parallel with respect to the reaction axis). The reverse effect happens if the direction of the OEF is flipped. OEF (when applied along the 'right' direction) helps to polarize the transition states in the desired direction, thereby facilitating favorable bonding interactions. Given the growing need for finding appropriate catalysts among the scientific community, OEF can prove to be a vital route for the same.
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Affiliation(s)
- Navya Arepalli
- Department of Chemistry, Birla Institute of Technology, Mesra, Ranchi 835215, Jharkhand, India
| | - Sukanta Mondal
- Department of Education, A. M. School of Educational Sciences, Assam University, Silchar 788011, Assam, India
| | - Debdutta Chakraborty
- Department of Chemistry, Birla Institute of Technology, Mesra, Ranchi 835215, Jharkhand, India
| | - Pratim Kumar Chattaraj
- Department of Chemistry, Birla Institute of Technology, Mesra, Ranchi 835215, Jharkhand, India
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7
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Zhang Y, Cao C, She Y, Yang YF, Houk KN. Molecular Dynamics of Iron Porphyrin-Catalyzed C-H Hydroxylation of Ethylbenzene. J Am Chem Soc 2023. [PMID: 37329571 DOI: 10.1021/jacs.3c03773] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Quasi-classical molecular dynamics (MD) simulations were carried out to study the mechanism of iron porphyrin-catalyzed hydroxylation of ethylbenzene. The hydrogen atom abstraction from ethylbenzene by iron-oxo species is the rate-determining step, which generates the radical pair of iron-hydroxo species and the benzylic radical. In the subsequent radical rebound step, the iron-hydroxo species and benzylic radical recombine to form the hydroxylated product, which is barrierless on the doublet energy surface. In the gas-phase quasi-classical MD study on the doublet energy surface, 45% of the reactive trajectories lead directly to the hydroxylated product, and this increases to 56% in implicit solvent model simulations. The percentage of reactive trajectories leading to the separated radical pair is 98-100% on high-spin (quartet/sextet) energy surfaces. The low-spin state reactivity dominates in the hydroxylation of ethylbenzene, which is dynamically both concerted and stepwise, since the time gap between C-H bond cleavage and C-O bond formation ranges from 41 to 619 fs. By contrast, the high-spin state catalysis is an energetically stepwise process, which has a negligible contribution to the formation of hydroxylation products.
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Affiliation(s)
- Yaling Zhang
- College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China
| | - Chaoqin Cao
- College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China
| | - Yuanbin She
- College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China
| | - Yun-Fang Yang
- College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China
| | - K N Houk
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
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8
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Zhou M, Tsien J, Dykstra R, Hughes JME, Peters BK, Merchant RR, Gutierrez O, Qin T. Alkyl sulfinates as cross-coupling partners for programmable and stereospecific installation of C(sp 3) bioisosteres. Nat Chem 2023; 15:550-559. [PMID: 36864142 PMCID: PMC10838399 DOI: 10.1038/s41557-023-01150-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 01/30/2023] [Indexed: 03/04/2023]
Abstract
In recent years, a variety of cycloalkyl groups with quaternary carbons, in particular cyclopropyl and cyclobutyl trifluoromethyl groups, have emerged as promising bioisosteres in drug-like molecules. The modular installation of such bioisosteres remains challenging to synthetic chemists. Alkyl sulfinate reagents have been developed as radical precursors to prepare functionalized heterocycles with the desired alkyl bioisosteres. However, the innate (radical) reactivity of this transformation poses reactivity and regioselectivity challenges for the functionalization of any aromatic or heteroaromatic scaffold. Here we showcase the ability of alkyl sulfinates to engage in sulfurane-mediated C(sp3)-C(sp2) cross-coupling, thereby allowing for programmable and stereospecific installation of these alkyl bioisosteres. The ability of this method to simplify retrosynthetic analysis is exemplified by the improved synthesis of multiple medicinally relevant scaffolds. Experimental studies and theoretical calculations for the mechanism of this sulfur chemistry reveal a ligand-coupling trend under alkyl Grignard activation via the sulfurane intermediate, stabilized by solvation of tetrahydrofuran.
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Affiliation(s)
- Min Zhou
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Harry Hines Blvd, Dallas, TX, USA
| | - Jet Tsien
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Harry Hines Blvd, Dallas, TX, USA
| | - Ryan Dykstra
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, USA
| | - Jonathan M E Hughes
- Department of Process Research and Development, Merck & Co., Inc., Rahway, NJ, USA
| | - Byron K Peters
- Department of Process Research and Development, Merck & Co., Inc., Rahway, NJ, USA
| | - Rohan R Merchant
- Department of Discovery Chemistry, Merck & Co., Inc., South San Francisco, CA, USA
| | - Osvaldo Gutierrez
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, USA.
- Department of Chemistry, Texas A&M University, College Station, TX, USA.
| | - Tian Qin
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Harry Hines Blvd, Dallas, TX, USA.
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9
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Joy J, Ess DH. Direct Dynamics Trajectories Demonstrate Dynamic Matching and Nonstatistical Radical Pair Intermediates during Fe-Oxo-Mediated C-H Functionalization Reactions. J Am Chem Soc 2023; 145:7628-7637. [PMID: 36952628 DOI: 10.1021/jacs.3c01196] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
The generally proposed mechanism for the reaction between non-heme Fe-oxo complexes and alkane C-H bonds involves a hydrogen atom transfer (HAT) reaction step with a radical pair intermediate that then has competitive radical rebound, dissociation, or desaturation pathways. Here, we report density functional theory-based quasiclassical direct dynamics trajectories that examine post-HAT reaction dynamics. Trajectories revealed that the radical pair intermediate can be a nonstatistical type intermediate without complete internal vibrational redistribution and post-HAT selectivity is generally determined by dynamic effects. Fast rebound trajectories occur through dynamic matching between the rotational motion of the newly formed Fe-OH bond and collision with the alkane radical, and all of this occurs through a nonsynchronous dynamically concerted process that circumvents the radical pair intermediate structure. For radical pair dissociation, trajectories proceeded to the radical pair intermediate for a very brief time, followed by complete dissociation. These trajectories provide a new viewpoint and model to understand the inherent reaction pathway selectivity for non-heme Fe-oxo-mediated C-H functionalization reactions.
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Affiliation(s)
- Jyothish Joy
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, United States
| | - Daniel H Ess
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, United States
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10
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A quantum-classical correspondence in the dynamics around higher order saddle points: a Bohmian perspective. Theor Chem Acc 2023. [DOI: 10.1007/s00214-023-02957-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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11
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Murakami T, Matsumoto N, Takayanagi T, Fujihara T. The importance of nuclear dynamics in reaction mechanisms of acetylene cyclotrimerization catalyzed by Fe+-compounds. J Organomet Chem 2023. [DOI: 10.1016/j.jorganchem.2023.122643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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12
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Guo W, Hare SR, Chen SS, Saunders CM, Tantillo DJ. C-H Insertion in Dirhodium Tetracarboxylate-Catalyzed Reactions despite Dynamical Tendencies toward Fragmentation: Implications for Reaction Efficiency and Catalyst Design. J Am Chem Soc 2022; 144:17219-17231. [PMID: 36098581 DOI: 10.1021/jacs.2c07681] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rh-catalyzed C-H insertion reactions to form β-lactones suffer from post-transition state bifurcations, with the same transition states leading to ketones and ketenes via fragmentation in addition to β-lactones. In such a circumstance, traditional transition state theory cannot predict product selectivity, so we employed ab initio molecular dynamics simulations to do so and provide a framework for rationalizing the origins of said selectivity. Weak interactions between the catalyst and substrate were studied using energy decomposition and noncovalent interaction analyses, which unmasked an important role of the 2-bromophenyl substituent that has been used in multiple β-lactone-forming C-H insertion reactions. Small and large catalysts were shown to behave differently, with the latter providing a means of overcoming dynamically preferred fragmentation by lowering the barrier for the recombination of the product fragments in the grip of the large catalyst active site cavity.
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Affiliation(s)
- Wentao Guo
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Stephanie R Hare
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Shu-Sen Chen
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Carla M Saunders
- 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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13
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Soler J, Gergel S, Klaus C, Hammer SC, Garcia-Borràs M. Enzymatic Control over Reactive Intermediates Enables Direct Oxidation of Alkenes to Carbonyls by a P450 Iron-Oxo Species. J Am Chem Soc 2022; 144:15954-15968. [PMID: 35998887 PMCID: PMC9460782 DOI: 10.1021/jacs.2c02567] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
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The aerobic oxidation of alkenes to carbonyls is an important
and
challenging transformation in synthesis. Recently, a new P450-based
enzyme (aMOx) has been evolved in the laboratory to directly oxidize
styrenes to their corresponding aldehydes with high activity and selectivity.
The enzyme utilizes a heme-based, high-valent iron-oxo species as
a catalytic oxidant that normally epoxidizes alkenes, similar to other
catalysts. How the evolved aMOx enzyme suppresses the commonly preferred
epoxidation and catalyzes direct carbonyl formation is currently not
well understood. Here, we combine computational modelling together
with mechanistic experiments to study the reaction mechanism and unravel
the molecular basis behind the selectivity achieved by aMOx. Our results
describe that although both pathways are energetically accessible
diverging from a common covalent radical intermediate, intrinsic dynamic effects determine the strong preference for epoxidation.
We discovered that aMOx overrides these intrinsic preferences by controlling
the accessible conformations of the covalent radical intermediate.
This disfavors epoxidation and facilitates the formation of a carbocation
intermediate that generates the aldehyde product through a fast 1,2-hydride
migration. Electrostatic preorganization of the enzyme active site
also contributes to the stabilization of the carbocation intermediate.
Computations predicted that the hydride migration is stereoselective
due to the enzymatic conformational control over the intermediate
species. These predictions were corroborated by experiments using
deuterated styrene substrates, which proved that the hydride migration
is cis- and enantioselective. Our results demonstrate
that directed evolution tailored a highly specific active site that
imposes strong steric control over key fleeting biocatalytic intermediates,
which is essential for accessing the carbonyl forming pathway and
preventing competing epoxidation.
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Affiliation(s)
- Jordi Soler
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Carrer Maria Aurèlia Capmany 69, Girona 17003, Catalonia, Spain
| | - Sebastian Gergel
- Chair of Organic Chemistry and Biocatalysis, Faculty of Chemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Cindy Klaus
- Chair of Organic Chemistry and Biocatalysis, Faculty of Chemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Stephan C Hammer
- Chair of Organic Chemistry and Biocatalysis, Faculty of Chemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Marc Garcia-Borràs
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Carrer Maria Aurèlia Capmany 69, Girona 17003, Catalonia, Spain
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14
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Pandey P, Keshavamurthy S. Dynamic matching ‐ revisiting the Carpenter model. J PHYS ORG CHEM 2022. [DOI: 10.1002/poc.4404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Priyanka Pandey
- Department of Chemistry Indian Institute of Technology Kanpur Uttar Pradesh India
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15
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Lan J, Li X, Yang Y, Zhang X, Chung LW. New Insights and Predictions into Complex Homogeneous Reactions Enabled by Computational Chemistry in Synergy with Experiments: Isotopes and Mechanisms. Acc Chem Res 2022; 55:1109-1123. [PMID: 35385649 DOI: 10.1021/acs.accounts.1c00774] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Homogeneous catalysis and biocatalysis have been widely applied in synthetic, medicinal, and energy chemistry as well as synthetic biology. Driven by developments of new computational chemistry methods and better computer hardware, computational chemistry has become an essentially indispensable mechanistic "instrument" to help understand structures and decipher reaction mechanisms in catalysis. In addition, synergy between computational and experimental chemistry deepens our mechanistic understanding, which further promotes the rational design of new catalysts. In this Account, we summarize new or deeper mechanistic insights (including isotope, dispersion, and dynamical effects) into several complex homogeneous reactions from our systematic computational studies along with subsequent experimental studies by different groups. Apart from uncovering new mechanisms in some reactions, a few computational predictions (such as excited-state heavy-atom tunneling, steric-controlled enantioswitching, and a new geminal addition mechanism) based on our mechanistic insights were further verified by ensuing experiments.The Zimmerman group developed a photoinduced triplet di-π-methane rearrangement to form cyclopropane derivatives. Recently, our computational study predicted the first excited-state heavy-atom (carbon) quantum tunneling in one triplet di-π-methane rearrangement, in which the reaction rates and 12C/13C kinetic isotope effects (KIEs) can be enhanced by quantum tunneling at low temperatures. This unprecedented excited-state heavy-atom tunneling in a photoinduced reaction has recently been verified by an experimental 12C/13C KIE study by the Singleton group. Such combined computational and experimental studies should open up opportunities to discover more rare excited-state heavy-atom tunneling in other photoinduced reactions. In addition, we found unexpectedly large secondary KIE values in the five-coordinate Fe(III)-catalyzed hetero-Diels-Alder pathway, even with substantial C-C bond formation, due to the non-negligible equilibrium isotope effect (EIE) derived from altered metal coordination. Therefore, these KIE values cannot reliably reflect transition-state structures for the five-coordinate metal pathway. Furthermore, our density functional theory (DFT) quasi-classical molecular dynamics (MD) simulations demonstrated that the coordination mode and/or spin state of the iron metal as well as an electric field can affect the dynamics of this reaction (e.g., the dynamically stepwise process, the entrance/exit reaction channels).Moreover, we unveiled a new reaction mechanism to account for the uncommon Ru(II)-catalyzed geminal-addition semihydrogenation and hydroboration of silyl alkynes. Our proposed key gem-Ru(II)-carbene intermediates derived from double migrations on the same alkyne carbon were verified by crossover experiments. Additionally, our DFT MD simulations suggested that the first hydrogen migration transition-state structures may directly and quickly form the key gem-Ru-carbene structures, thereby "bypassing" the second migration step. Furthermore, our extensive study revealed the origin of the enantioselectivity of the Cu(I)-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with β-substituted alkenyl bicyclic heteroarenes enabled by dual coordination of both substrates. Such mechanistic insights promoted our computational predictions of the enantioselectivity reversal for the corresponding monocyclic heteroarene substrates and the regiospecific addition to the less reactive internal C═C bond of one diene substrate. These predictions were proven by our experimental collaborators. Finally, our mechanistic insights into a few other reactions are also presented. Overall, we hope that these interactive computational and experimental studies enrich our mechanistic understanding and aid in reaction development.
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Affiliation(s)
- Jialing Lan
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China
- Shenzhen Grubbs Institute, Department of Chemistry, and Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Xin Li
- Shenzhen Grubbs Institute, Department of Chemistry, and Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Yuhong Yang
- Shenzhen Grubbs Institute, Department of Chemistry, and Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Xiaoyong Zhang
- Shenzhen Grubbs Institute, Department of Chemistry, and Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Lung Wa Chung
- Shenzhen Grubbs Institute, Department of Chemistry, and Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
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Zhu M, Zheng C. Post-spin crossing dynamics determine the regioselectivity in open-shell singlet biradical recombination. Org Chem Front 2022. [DOI: 10.1039/d1qo01757h] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Comprehensive computational studies reveal unique dynamic effects in a multi-spin-state reaction that determine the regioselectivity of a biradical recombination process.
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Affiliation(s)
- Min Zhu
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai 200032, China
- School of Physical Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai 201210, China
| | - Chao Zheng
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai 200032, China
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