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Liu X, Tian S, Guo W, Li H, Pang B, Wu Y. Competing C and N as Reactive Centers for Microsolvated Ambident Nucleophiles CN -(H 2O) n=0-3: A Theoretical Study of E2/S N2 Reactions with CH 3CH 2X (X = Cl, Br, I). J Phys Chem A 2024; 128:4651-4662. [PMID: 38819200 DOI: 10.1021/acs.jpca.4c01226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
As an ambident nucleophile, CN- has both C and N atoms that can act as the reactive center to facilitate substitution reactions. We investigate in detail the potential energy profiles of CN-(H2O)0-3 with CH3CH2X (X = Cl, Br, I) to explore the influence of solvent molecules on competition between the different nucleophilic atoms C and N involving the SN2 and E2 pathways. The energy barrier sequence for the transition states follows C@inv-SN2 < N@inv-SN2 < C@anti-E2 < N@anti-E2. When two different atoms act as nucleophilic atoms, the SN2 reaction is always preferred over the E2 reaction, and this preference increases with microsolvation. For the ambident nucleophiles CN-(H2O)0-3, C as the reactive center always has stronger nucleophilicity and basicity than N acting as the reactive center. Regarding the leaving group, the height of the energy barrier is positively correlated with the acidity of the CH3CH2X substrate for the E2 pathway and with X-heterolysis for the SN2 pathway. Furthermore, we found that in the gas phase, the energy barrier for different leaving group systems decreases gradually in the order Cl > Br > I, while in the SMD solution, the energy barrier and product energy increase slightly in the system from X = Cl to Br; this change may be due to the significantly weakened transition-state interaction for the X = Br system. Our activation strain, quantitative molecular orbital, and charge analyses reveal the physical mechanisms underlying the various computed trends. In addition, we also demonstrate the two points recently proposed by Vermeeren, P. . Chem. Eur. J. 2020, 26, 15538-15548.
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Affiliation(s)
- Xu Liu
- College of Chemistry, Liaoning University, Shenyang 110036, China
| | - Shiqi Tian
- College of Chemistry, Liaoning University, Shenyang 110036, China
| | - Wenyu Guo
- College of Chemistry, Liaoning University, Shenyang 110036, China
| | - Hui Li
- College of Chemistry, Liaoning University, Shenyang 110036, China
| | - Boxue Pang
- Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines, School of Resources and Civil Engineering, Northeastern University, Shenyang 110819, China
| | - Yang Wu
- College of Chemistry, Liaoning University, Shenyang 110036, China
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2
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Horst B, van Duijnen N, Janssen E, Hansen T, Ruijter E. Modular Divergent Synthesis of Indole Alkaloid Derivatives by an Atypical Ugi Multicomponent Reaction. Chemistry 2024; 30:e202400477. [PMID: 38498145 DOI: 10.1002/chem.202400477] [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: 02/02/2024] [Revised: 03/13/2024] [Accepted: 03/18/2024] [Indexed: 03/20/2024]
Abstract
We present an Ugi multicomponent approach to explore the chemical space around Aspidosperma-type monoterpene indole alkaloids. By variation of the isocyanide and carboxylic acid inputs we demonstrate the rapid generation of molecular diversity and the possibility to introduce handles for further modification. The key Ugi three-component reaction showed full diastereoselectivity towards the cis-fused ring system, which can be rationalized by DFT calculations that moreover indicate that the reaction proceeds via a Passerini-type hydrogen bonding mechanism. Several post-Ugi modifications were also performed, including Pictet-Spengler cyclization to highly complex nonacyclic natural product hybrid scaffolds.
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Affiliation(s)
- Brendan Horst
- Department of Chemistry and Pharmaceutical Sciences, Amsterdam Institute for Molecular & Life Sciences (AIMMS), Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081, HZ Amsterdam, The Netherlands
| | - Niels van Duijnen
- Department of Chemistry and Pharmaceutical Sciences, Amsterdam Institute for Molecular & Life Sciences (AIMMS), Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081, HZ Amsterdam, The Netherlands
| | - Elwin Janssen
- Department of Chemistry and Pharmaceutical Sciences, Amsterdam Institute for Molecular & Life Sciences (AIMMS), Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081, HZ Amsterdam, The Netherlands
| | - Thomas Hansen
- Department of Chemistry and Pharmaceutical Sciences, Amsterdam Institute for Molecular & Life Sciences (AIMMS), Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081, HZ Amsterdam, The Netherlands
| | - Eelco Ruijter
- Department of Chemistry and Pharmaceutical Sciences, Amsterdam Institute for Molecular & Life Sciences (AIMMS), Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081, HZ Amsterdam, The Netherlands
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3
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Remmerswaal WA, de Jong T, van de Vrande KNA, Louwersheimer R, Verwaal T, Filippov DV, Codée JDC, Hansen T. Backside versus Frontside S N2 Reactions of Alkyl Triflates and Alcohols. Chemistry 2024; 30:e202400590. [PMID: 38385647 DOI: 10.1002/chem.202400590] [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: 02/20/2024] [Accepted: 02/22/2024] [Indexed: 02/23/2024]
Abstract
Nucleophilic substitution reactions are elementary reactions in organic chemistry that are used in many synthetic routes. By quantum chemical methods, we have investigated the intrinsic competition between the backside SN2 (SN2-b) and frontside SN2 (SN2-f) pathways using a set of simple alkyl triflates as the electrophile in combination with a systematic series of phenols and partially fluorinated ethanol nucleophiles. It is revealed how and why the well-established mechanistic preference for the SN2-b pathway slowly erodes and can even be overruled by the unusual SN2-f substitution mechanism going from strong to weak alcohol nucleophiles. Activation strain analyses disclose that the SN2-b pathway is favored for strong alcohol nucleophiles because of the well-known intrinsically more efficient approach to the electrophile resulting in a more stabilizing nucleophile-electrophile interaction. In contrast, the preference of weaker alcohol nucleophiles shifts to the SN2-f pathway, benefiting from a stabilizing hydrogen bond interaction between the incoming alcohol and the leaving group. This hydrogen bond interaction is strengthened by the increased acidity of the weaker alcohol nucleophiles, thereby steering the mechanistic preference toward the frontside SN2 pathway.
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Affiliation(s)
- Wouter A Remmerswaal
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
| | - Tjeerd de Jong
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
| | - Koen N A van de Vrande
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
| | - Rick Louwersheimer
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
| | - Thomas Verwaal
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
| | - Dmitri V Filippov
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
| | - Jeroen D C Codée
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
| | - Thomas Hansen
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
- Department of Chemistry and Pharmaceutical Sciences, AIMMS, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ, Amsterdam, The, Netherlands
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Wu X, Bickelhaupt FM, Xie J. Solvent-induced dual nucleophiles and the α-effect in the S N2 versus E2 competition. Phys Chem Chem Phys 2024; 26:11320-11330. [PMID: 38536735 PMCID: PMC11022550 DOI: 10.1039/d4cp00671b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 03/14/2024] [Indexed: 04/18/2024]
Abstract
We have quantum chemically investigated how microsolvation affects the various E2 and SN2 pathways, their mutual competition, and the α-effect of the model reaction system HOO-(H2O)n + CH3CH2Cl, at the CCSD(T) level. Interestingly, we identify the dual nature of the α-nucleophile HOO- which, upon solvation, is in equilibrium with HO-. This solvent-induced dual appearance gives rise to a rich network of competing reaction channels. Among both nucleophiles, SN2 is always favored over E2, and this preference increases upon increasing microsolvation. Furthermore, we found a pronounced α-effect, not only for SN2 substitution but also for E2 elimination, i.e., HOO- is more reactive than HO- in both cases. Our activation strain and quantitative molecular orbital analyses reveal the physical mechanisms behind the various computed trends. In particular, we demonstrate that two recently proposed criteria, required for solvent-free nucleophiles to display the α-effect, must also be satisfied by microsolvated HOO-(H2O)n nucleophiles.
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Affiliation(s)
- Xiangyu Wu
- Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, China.
| | - F Matthias Bickelhaupt
- Department of Chemistry and Pharmaceutical Sciences, AIMMS, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands.
- Institute for Molecules and Materials (IMM), Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
- Department of Chemical Sciences, University of Johannesburg, Auckland Park, Johannesburg 2006, South Africa
| | - Jing Xie
- Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, China.
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5
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de Azevedo Santos L, van der Voort S, Burema SR, Fonseca Guerra C, Bickelhaupt FM. Blueshift in Trifurcated Hydrogen Bonds: A Tradeoff between Tetrel Bonding and Steric Repulsion. Chemphyschem 2024; 25:e202300480. [PMID: 37864778 DOI: 10.1002/cphc.202300480] [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: 08/04/2023] [Revised: 10/17/2023] [Accepted: 10/20/2023] [Indexed: 10/23/2023]
Abstract
We have quantum chemically investigated the origin of the atypical blueshift of the H-C bond stretching frequency in the hydrogen-bonded complex X- •••H3 C-Y (X, Y=F, Cl, Br, I), as compared to the corresponding redshift occurring in Cl- •••H3 N and Cl- •••H3 C-H, using relativistic density functional theory (DFT) at ZORA-BLYP-D3(BJ)/QZ4P. Previously, this blueshift was attributed, among others, to the contraction of the H-C bonds as the H3 C moiety becomes less pyramidal. Herein, we provide quantitative evidence that, instead, the blueshift arises from a direct and strong X- •••C interaction of the HOMO of A- with the backside lobe on carbon of the low-lying C-Y antibonding σ* LUMO of the H3 C-Y fragment. This X- •••C bond, in essence a tetrel bond, pushes the H atoms towards a shorter H-C distance and makes the H3 C moiety more planar. The blueshift may, therefore, serve as a diagnostic for tetrel bonding.
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Affiliation(s)
- Lucas de Azevedo Santos
- Department of Chemistry and Pharmaceutical Sciences, AIMMS, Vrije Universiteit, Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Storm van der Voort
- Department of Chemistry and Pharmaceutical Sciences, AIMMS, Vrije Universiteit, Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Shiri R Burema
- Department of Chemistry and Pharmaceutical Sciences, AIMMS, Vrije Universiteit, Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Célia Fonseca Guerra
- Department of Chemistry and Pharmaceutical Sciences, AIMMS, Vrije Universiteit, Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - F Matthias Bickelhaupt
- Department of Chemistry and Pharmaceutical Sciences, AIMMS, Vrije Universiteit, Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
- Department of Chemical Sciences, University of Johannesburg Auckland Park, Johannesburg, 2006, South Africa
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6
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Zhao S, Fu G, Zhen W, Wang H, Yang L, Zhang J. Competitive dynamics of E2 and S N2 reaction driven by collision energy and leaving group. Phys Chem Chem Phys 2023; 25:28086-28093. [PMID: 37817676 DOI: 10.1039/d3cp03832g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
The competition between E2 and SN2 reactions is essential in organic chemistry. In this paper, the reaction mechanism of F- + CH3CH2Cl is investigated utilizing direct dynamics simulations, and unravel how the collision energy (Ecoll) and the leaving group affect the competition between SN2 and E2 in the F- + CH3CH2Y (Y = Cl and Br) reactions. Simulation results for F- + CH3CH2Cl reaction show that the anti-E2 channel is dominant, but with the increase of Ecoll from 0.04 to 1.9 eV the branching ratio of the anti-E2 pathway significantly decreases by 21%, and the SN2 pathway becomes more important. A transition from indirect to direct reaction has been revealed when Ecoll is increased from 0.04 to 1.90 eV. At lower Ecoll, a large ratio of indirect events occurs via a long-lived hydrogen-bonded complex, and as the collision energy is increased, the lifetimes of the hydrogen-bonded complexes are shortened, due to an initial faster relative velocity. The simulation results of F- + CH3CH2Cl are further compared with the F- + CH3CH2Br reaction at Ecoll of 0.04 eV. Changing the leaving group from Cl to Br drastically suppresses the indirect events of anti-E2 with a branching ratio decreasing from 0.46 to 0.36 due to the mass effect, and promotes direct rebound mechanism resulting from a looser transition state geometry caused by varied electronegativity.
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Affiliation(s)
- Siwei Zhao
- State Key Laboratory of Urban Water Resource and Environment, MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China.
| | - Gang Fu
- State Key Laboratory of Urban Water Resource and Environment, MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China.
| | - Wenqing Zhen
- State Key Laboratory of Urban Water Resource and Environment, MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China.
| | - Hongyi Wang
- State Key Laboratory of Urban Water Resource and Environment, MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China.
| | - Li Yang
- State Key Laboratory of Urban Water Resource and Environment, MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China.
| | - Jiaxu Zhang
- State Key Laboratory of Urban Water Resource and Environment, MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China.
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7
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Liu X, Guo W, Feng H, Pang B, Wu Y. Competition between Elimination and Substitution for Ambident Nucleophiles CN - and Iodoethane Reactions in Gaseous and Aqueous Medium. J Phys Chem A 2023; 127:7373-7382. [PMID: 37639466 DOI: 10.1021/acs.jpca.3c04630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Nucleophilic substitution (SN2) and elimination (E2) reactions between ambident nucleophiles have long been considered as typical reactions in organic chemistry, and exploring the competition between the two reactions is of great importance in chemical synthesis. As a nucleophile, CN- can use its C and N atoms as the reactive centers to undergo E2 and SN2 reactions, but related research is currently limited. This study uses the CCSD(T)/pp/t//MP2/ECP/d electronic structure method to perform detailed investigations on the potential energy profiles for SN2 and E2 reactions between CN- and CH3CH2I in gaseous and aqueous media. The potential energy profiles reveal that the energy barriers for SN2 and E2 reactions with the C atom as the reactive center are consistently lower than those with the N atom, indicating that the C atom has a stronger nucleophilic ability and stronger basicity. Furthermore, the potential energy profiles in both gas and aqueous environments show that the barriers of SN2 reactions are lower than those for E2 reactions with both C and N as the attacking atom. By using the frontier molecular orbital and activation strain models to explain the interesting phenomenon, the transition from the gas phase to solution was investigated, specifically in the gas-microsolvation-water transition. The results show that water molecules reduce the nucleophilicity and basicity of CN-, while strain energy (ΔEstrain) causes a greater increase in the energy barrier for E2 reactions. This study provides new insights and perspectives on the understanding of CN- as a nucleophile in SN2 reactions and serves as theoretical guidance for organic synthesis.
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Affiliation(s)
- Xu Liu
- College of Chemistry, Liaoning University, Shenyang 110036, P. R. China
| | - Wenyu Guo
- College of Chemistry, Liaoning University, Shenyang 110036, P. R. China
| | - Huining Feng
- College of Chemistry, Liaoning University, Shenyang 110036, P. R. China
| | - Boxue Pang
- Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines, School of Resources and Civil Engineering, Northeastern University, Shenyang 110819, China
| | - Yang Wu
- College of Chemistry, Liaoning University, Shenyang 110036, P. R. China
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8
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Hansen T, Vermeeren P, Zijderveld KWJ, Bickelhaupt FM, Hamlin TA. S N 2 versus E2 Competition of Cyclic Ethers. Chemistry 2023; 29:e202301308. [PMID: 37338310 DOI: 10.1002/chem.202301308] [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: 04/26/2023] [Revised: 06/20/2023] [Accepted: 06/20/2023] [Indexed: 06/21/2023]
Abstract
We have quantum chemically studied the influence of ring strain on the competition between the two mechanistically different SN 2 and E2 pathways using a series of archetypal ethers as substrate in combination with a diverse set of Lewis bases (F- , Cl- , Br- , HO- , H3 CO- , HS- , H3 CS- ), using relativistic density functional theory at ZORA-OLYP/QZ4P. The ring strain in the substrate is systematically increased on going from a model acyclic ether to a 6- to 5- to 4- to 3-membered ether ring. We have found that the activation energy of the SN 2 pathway sharply decreases when the ring strain of the system is increased, thus on going from large to small cyclic ethers, the SN 2 reactivity increases. In contrast, the activation energy of the E2 pathway generally rises along this same series, that is, from large to small cyclic ethers. The opposing reactivity trends induce a mechanistic switch in the preferred reaction pathway for strong Lewis bases from E2, for large cyclic substrates, to SN 2, for small cyclic substrates. Weak Lewis bases are unable to overcome the higher intrinsic distortivity of the E2 pathway and, therefore, always favor the less distortive SN 2 reaction.
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Affiliation(s)
- Thomas Hansen
- Department of Chemistry and Pharmaceutical Sciences, Amsterdam Institute of Molecular and Life Sciences (AIMMS) Vrije Universiteit, Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam (The, Netherlands
| | - Pascal Vermeeren
- Department of Chemistry and Pharmaceutical Sciences, Amsterdam Institute of Molecular and Life Sciences (AIMMS) Vrije Universiteit, Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam (The, Netherlands
| | - Kim W J Zijderveld
- Department of Chemistry and Pharmaceutical Sciences, Amsterdam Institute of Molecular and Life Sciences (AIMMS) Vrije Universiteit, Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam (The, Netherlands
| | - F Matthias Bickelhaupt
- Department of Chemistry and Pharmaceutical Sciences, Amsterdam Institute of Molecular and Life Sciences (AIMMS) Vrije Universiteit, Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam (The, Netherlands
- Institute for Molecules and Materials (IMM), Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen (The, Netherlands
- Department of Chemical Sciences, University of Johannesburg, Auckland Park, Johannesburg, 2006, South Africa
| | - Trevor A Hamlin
- Department of Chemistry and Pharmaceutical Sciences, Amsterdam Institute of Molecular and Life Sciences (AIMMS) Vrije Universiteit, Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam (The, Netherlands
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9
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Zhen W, Zhao S, Fu G, Wang H, Sun J, Yang L, Zhang J. Effects of Methyl Substitution and Leaving Group on E2/S N2 Competition for Reactions of F - with RY (R = CH 3, C 2H 5, iC 3H 7, tC 4H 9; Y = Cl, I). Molecules 2023; 28:6269. [PMID: 37687098 PMCID: PMC10488877 DOI: 10.3390/molecules28176269] [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: 08/03/2023] [Revised: 08/22/2023] [Accepted: 08/24/2023] [Indexed: 09/10/2023] Open
Abstract
The competition between base-induced elimination (E2) and bimolecular nucleophilic substitution (SN2) is of significant importance in organic chemistry and is influenced by many factors. The electronic structure calculations for the gas-phase reactions of F- + RY (R = CH3, C2H5, iC3H7, tC4H9, and Y = Cl, I) are executed at the MP2 level with aug-cc-pVDZ or ECP/d basis set to investigate the α-methyl substitution effect. The variation in barrier height, reaction enthalpy, and competition of SN2/E2 as a function of methyl-substitution and leaving group ability has been emphasized. And the nature of these rules has been explored. As the degree of methyl substitution on α-carbon increases, the E2 channel becomes more competitive and dominant with R varying from C2H5, iC3H7, to tC4H9. Energy decomposition analysis offers new insights into the competition between E2 and SN2 processes, which suggests that the drop in interaction energy with an increasing degree of substitution cannot compensate for the rapid growth of preparation energy, leading to a rapid increase in the SN2 energy barrier. By altering the leaving group from Cl to I, the barriers of both SN2 and E2 monotonically decrease, and, with the increased number of substituents, they reduce more dramatically, which is attributed to the looser transition state structures with the stronger leaving group ability. Interestingly, ∆E0‡ exhibits a positive linear correlation with reaction enthalpy (∆H) and halogen electronegativity. With the added number of substituents, the differences in ∆E0‡ and ∆H between Y = Cl and I likewise exhibit good linearity.
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Affiliation(s)
| | | | | | | | | | - Li Yang
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China; (W.Z.); (S.Z.); (G.F.); (H.W.); (J.S.)
| | - Jiaxu Zhang
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China; (W.Z.); (S.Z.); (G.F.); (H.W.); (J.S.)
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Remmerswaal WA, Hansen T, Hamlin TA, Codée JDC. Origin of Stereoselectivity in S E 2' Reactions of Six-membered Ring Oxocarbenium Ions. Chemistry 2023; 29:e202203490. [PMID: 36511875 DOI: 10.1002/chem.202203490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 12/09/2022] [Accepted: 12/13/2022] [Indexed: 12/15/2022]
Abstract
Oxocarbenium ions are key reactive intermediates in organic chemistry. To generate a series of structure-reactivity-stereoselectivity principles for these species, we herein investigated the bimolecular electrophilic substitution reactions (SE 2') between allyltrimethylsilane and a series of archetypal six-membered ring oxocarbenium ions using a combined density functional theory (DFT) and coupled-cluster theory approach. These reactions preferentially proceed following a reaction path where the oxocarbenium ion transforms from a half chair (3 H4 or 4 H3 ) to a chair conformation. The introduction of alkoxy substituents on six-membered ring oxocarbenium ions, dramatically influences the conformational preference of the canonical 3 H4 and 4 H3 conformers, and thereby the stereochemical outcome of the SE 2' reaction. In general, we find that the stereoselectivity in the reactions correlates to the "intrinsic preference" of the cations, as dictated by their shape. However, for the C5-CH2 OMe substituent, steric factors override the "intrinsic preference", showing a more selective reaction than expected based on the shape of the ion. Our SE 2' energetics correlate well with experimentally observed stereoselectivity, and the use of the activation strain model has enabled us to quantify important interactions and structural features that occur in the transition state of the reactions to precisely understand the relative energy barriers of the diastereotopic addition reactions. The fundamental mechanistic insight provided in this study will aid in understanding the reactivity of more complex glycosyl cations featuring multiple substituents and will facilitate our general understanding of glycosylation reactions.
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Affiliation(s)
- Wouter A Remmerswaal
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden (The, Netherlands
| | - Thomas Hansen
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden (The, Netherlands.,Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam (The, Netherlands
| | - Trevor A Hamlin
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam (The, Netherlands
| | - Jeroen D C Codée
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden (The, Netherlands
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11
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Sun X, Hansen T, Poater J, Hamlin TA, Bickelhaupt FM. Rational design of iron catalysts for C-X bond activation. J Comput Chem 2023; 44:495-505. [PMID: 35137432 PMCID: PMC10078697 DOI: 10.1002/jcc.26818] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 01/16/2022] [Accepted: 01/20/2022] [Indexed: 01/10/2023]
Abstract
We have quantum chemically studied the iron-mediated CX bond activation (X = H, Cl, CH3 ) by d8 -FeL4 complexes using relativistic density functional theory at ZORA-OPBE/TZ2P. We find that by either modulating the electronic effects of a generic iron-catalyst by a set of ligands, that is, CO, BF, PH3 , BN(CH3 )2 , or by manipulating structural effects through the introduction of bidentate ligands, that is, PH2 (CH2 )n PH2 with n = 6-1, one can significantly decrease the reaction barrier for the CX bond activation. The combination of both tuning handles causes a decrease of the CH activation barrier from 10.4 to 4.6 kcal mol-1 . Our activation strain and Kohn-Sham molecular orbital analyses reveal that the electronic tuning works via optimizing the catalyst-substrate interaction by introducing a strong second backdonation interaction (i.e., "ligand-assisted" interaction), while the mechanism for structural tuning is mainly caused by the reduction of the required activation strain because of the pre-distortion of the catalyst. In all, we present design principles for iron-based catalysts that mimic the favorable behavior of their well-known palladium analogs in the bond-activation step of cross-coupling reactions.
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Affiliation(s)
- Xiaobo Sun
- Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.,Departament de Química Inorgànica i Orgànica & IQTCUB, Universitat de Barcelona, Barcelona, Spain
| | - Thomas Hansen
- Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.,Departament de Química Inorgànica i Orgànica & IQTCUB, Universitat de Barcelona, Barcelona, Spain.,Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - Jordi Poater
- Departament de Química Inorgànica i Orgànica & IQTCUB, Universitat de Barcelona, Barcelona, Spain.,ICREA, Barcelona, Spain
| | - Trevor A Hamlin
- Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Friedrich Matthias Bickelhaupt
- Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.,Institute for Molecules and Materials (IMM), Radboud University, Nijmegen, The Netherlands
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12
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Escorihuela J. A Density Functional Theory Study on the Cobalt-Mediated Intramolecular Pauson–Khand Reaction of Enynes Containing a Vinyl Fluoride Moiety. SYNTHESIS-STUTTGART 2022. [DOI: 10.1055/s-0042-1751392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
AbstractThe Co2(CO)8-mediated intramolecular Pauson–Khand reaction (PKR) is an effective method for constructing polycyclic structures. Recently, our group reported a series of this type of reaction involving fluorinated enynes that proceed with reasonable reaction rates and yields. However, mechanistic studies involving these fluorinated derivatives in intramolecular PKR are scarce. In this study, density functional theory calculations are used to clarify the mechanism and reactivity of enynes containing a vinyl fluoride moiety for this reaction. In agreement with previous studies, alkene insertion is considered to be the rate-determining step for the overall Pauson–Khand reaction of enynes containing a vinyl fluoride moiety. The effect of the substituent on the Co2(CO)8-mediated intramolecular Pauson–Khand reaction has also been investigated. When introducing heteroatoms as tethering units, the fluorinated enynes exhibited lower reactivity than the malonate homologues, whereas the use of a sulfur-based tether was unsuccessful. This computational study provides detailed information about the PKR mechanism and transition-state structures, and the results are validated with previous experimental results.
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13
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Hansen T, Nin-Hill A, Codée JDC, Hamlin TA, Rovira C. Rational Tuning of the Reactivity of Three-Membered Heterocycle Ring Openings via S N 2 Reactions. Chemistry 2022; 28:e202201649. [PMID: 35896443 DOI: 10.1002/chem.202201649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Indexed: 01/07/2023]
Abstract
The development of small-molecule covalent inhibitors and probes continuously pushes the rapidly evolving field of chemical biology forward. A key element in these molecular tool compounds is the "electrophilic trap" that allows a covalent linkage with the target enzyme. The reactivity of this entity needs to be well balanced to effectively trap the desired enzyme, while not being attacked by off-target nucleophiles. Here we investigate the intrinsic reactivity of substrates containing a class of widely used electrophilic traps, the three-membered heterocycles with a nitrogen (aziridine), phosphorus (phosphirane), oxygen (epoxide) or sulfur atom (thiirane) as heteroatom. Using quantum chemical approaches, we studied the conformational flexibility and nucleophilic ring opening of a series of model substrates, in which these electrophilic traps are mounted on a cyclohexene scaffold (C6 H10 Y with Y=NH, PH, O, S). It was revealed that the activation energy of the ring opening does not necessarily follow the trend that is expected from C-Y leaving-group bond strength, but steeply decreases from Y=NH, to PH, to O, to S. We illustrate that the HOMONu -LUMOSubstrate interaction is an all-important factor for the observed reactivity. In addition, we show that the activation energy of aziridines and phosphiranes can be tuned far below that of the corresponding epoxides and thiiranes by the addition of proper electron-withdrawing ring substituents. Our results provide mechanistic insights to rationally tune the reactivity of this class of popular electrophilic traps and can guide the experimental design of covalent inhibitors and probes for enzymatic activity.
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Affiliation(s)
- Thomas Hansen
- Departament de Química Inorgànica i Orgànica (Secció de Química Orgànica) &, Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, 08028, Barcelona, Spain.,Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam (The, Netherlands
| | - Alba Nin-Hill
- Departament de Química Inorgànica i Orgànica (Secció de Química Orgànica) &, Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, 08028, Barcelona, Spain
| | - Jeroen D C Codée
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden (The, Netherlands
| | - Trevor A Hamlin
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam (The, Netherlands
| | - Carme Rovira
- Departament de Química Inorgànica i Orgànica (Secció de Química Orgànica) &, Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, 08028, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), 08020, Barcelona, Spain
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14
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Hansen T, Sun X, Dalla Tiezza M, van Zeist W, van Stralen JNP, Geerke DP, Wolters LP, Poater J, Hamlin TA, Bickelhaupt FM. C−X Bond Activation by Palladium: Steric Shielding versus Steric Attraction. Chemistry 2022; 28:e202201093. [PMID: 35420229 PMCID: PMC9401605 DOI: 10.1002/chem.202201093] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Indexed: 11/07/2022]
Abstract
The C−X bond activation (X = H, C) of a series of substituted C(n°)−H and C(n°)−C(m°) bonds with C(n°) and C(m°) = H3C− (methyl, 0°), CH3H2C− (primary, 1°), (CH3)2HC− (secondary, 2°), (CH3)3C− (tertiary, 3°) by palladium were investigated using relativistic dispersion‐corrected density functional theory at ZORA‐BLYP‐D3(BJ)/TZ2P. The effect of the stepwise introduction of substituents was pinpointed at the C−X bond on the bond activation process. The C(n°)−X bonds become substantially weaker going from C(0°)−X, to C(1°)−X, to C(2°)−X, to C(3°)−X because of the increasing steric repulsion between the C(n°)‐ and X‐group. Interestingly, this often does not lead to a lower barrier for the C(n°)−X bond activation. The C−H activation barrier, for example, decreases from C(0°)−X, to C(1°)−X, to C(2°)−X and then increases again for the very crowded C(3°)−X bond. For the more congested C−C bond, in contrast, the activation barrier always increases as the degree of substitution is increased. Our activation strain and matching energy decomposition analyses reveal that these differences in C−H and C−C bond activation can be traced back to the opposing interplay between steric repulsion across the C−X bond versus that between the catalyst and substrate.
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Affiliation(s)
- Thomas Hansen
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands
- Leiden Institute of Chemistry Leiden University Einsteinweg 55 2333 CC Leiden The Netherlands
- Departament de Química Inorgànicai i Orgànica & IQTCUB Universitat de Barcelona Martí i Franquès 1-11 08028 Barcelona Spain
| | - Xiaobo Sun
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands
- Departament de Química Inorgànicai i Orgànica & IQTCUB Universitat de Barcelona Martí i Franquès 1-11 08028 Barcelona Spain
| | - Marco Dalla Tiezza
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands
| | - Willem‐Jan van Zeist
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands
| | - Joost N. P. van Stralen
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands
| | - Daan P. Geerke
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands
| | - Lando P. Wolters
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands
| | - Jordi Poater
- Departament de Química Inorgànicai i Orgànica & IQTCUB Universitat de Barcelona Martí i Franquès 1-11 08028 Barcelona Spain
- ICREA Passeig Lluís Companys 23 08010 Barcelona Spain
| | - Trevor A. Hamlin
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands
| | - F. Matthias Bickelhaupt
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands
- Institute for Molecules and Materials (IMM) Radboud University Heyendaalseweg 135 6525 AJ Nijmegen The Netherlands
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15
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Unexpected steric hindrance failure in the gas phase F - + (CH 3) 3CI S N2 reaction. Nat Commun 2022; 13:4427. [PMID: 35907925 PMCID: PMC9338938 DOI: 10.1038/s41467-022-32191-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
Base-induced elimination (E2) and bimolecular nucleophilic substitution (SN2) reactions are of significant importance in physical organic chemistry. The textbook example of the retardation of SN2 reactivity by bulky alkyl substitution is widely accepted based on the static analysis of molecular structure and steric environment. However, the direct dynamical evidence of the steric hindrance of SN2 from experiment or theory remains rare. Here, we report an unprecedented full-dimensional (39-dimensional) machine learning-based potential energy surface for the 15-atom F− + (CH3)3CI reaction, facilitating the reliable and efficient reaction dynamics simulations that can reproduce well the experimental outcomes and examine associated atomic-molecular level mechanisms. Moreover, we found surprisingly high “intrinsic” reactivity of SN2 when the E2 pathway is completely blocked, indicating the reaction that intends to proceed via E2 transits to SN2 instead, due to a shared pre-reaction minimum. This finding indicates that the competing factor of E2 but not the steric hindrance determines the small reactivity of SN2 for the F− + (CH3)3CI reaction. Our study provides new insight into the dynamical origin that determines the intrinsic reactivity in gas-phase organic chemistry. Base-induced elimination (E2) and bimolecular nucleophilic substitution (SN2) are of significant importance in physical organic chemistry. Here, the authors show that the competing factor of E2 as opposed to steric hindrance determines the low reactivity of SN2 in the F− + (CH3)3CI reaction.
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16
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García-Aznar P, Escorihuela J. Computational insights into the inverse electron-demand Diels-Alder reaction of norbornenes with 1,2,4,5-tetrazines: norbornene substituents' effects on the reaction rate. Org Biomol Chem 2022; 20:6400-6412. [PMID: 35876298 DOI: 10.1039/d2ob01121b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The study of the reaction rates and mechanism of click chemistry reactions still remains an interesting challenge in organic chemistry. In this regard, the inverse electron demand Diels-Alder (IEDDA) reaction represents a promising metal-free alternative with enhanced reaction rates compared to other reactions of the click chemistry toolbox. Among the different types of dienophiles used in the IEDDA reactions, norbornenes have been widely used given their high stability and fast reaction rates. The inverse electron-demand Diels Alder reaction of 3,6-dipyridin-2-yl-1,2,4,5-tetrazine with a series of norbornene derivatives was studied with quantum mechanical calculations at the M06-2X/6-311+G(d,p) level of theory. The theoretical predictions were confirmed with the experimental data and analyzed with the use of the distortion/interaction model. The obtained results will help in obtaining a better understanding of the factors that affect the relative cycloaddition rates of norbornenes with tetrazines, which are crucial for selectively tuning their efficacy.
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Affiliation(s)
- Pablo García-Aznar
- Departamento de Química Orgánica, Facultad de Farmacia, Universitat de València, Avda. Vicente Andrés Estellés, s/n, Burjassot 46100, València, Spain.
| | - Jorge Escorihuela
- Departamento de Química Orgánica, Facultad de Farmacia, Universitat de València, Avda. Vicente Andrés Estellés, s/n, Burjassot 46100, València, Spain.
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17
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Vermeeren P, Hamlin TA, Bickelhaupt FM. How Ionization Catalyzes Diels–Alder Reactions. Chemistry 2022; 28:e202201620. [DOI: 10.1002/chem.202201620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Pascal Vermeeren
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081HV Amsterdam The Netherlands
| | - Trevor A. Hamlin
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081HV Amsterdam The Netherlands
| | - F. Matthias Bickelhaupt
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081HV Amsterdam The Netherlands
- Institute for Molecules and Materials Radboud University Nijmegen Heyendaalseweg 135 6525AJ Nijmegen The Netherlands
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18
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Abstract
We have quantum chemically explored the competition between the SN2 and SN2' pathways for X- + H2C═CHCH2Y (X, Y = F, Cl, Br, I) using a combined relativistic density functional theory and coupled-cluster theory approach. Bimolecular nucleophilic substitution reactions at allylic systems, i.e., Cγ═Cβ-Cα-Y, bearing a leaving-group at the α-position, proceed either via a direct attack at the α-carbon (SN2) or via an attack at the γ-carbon, involving a concerted allylic rearrangement (SN2'), in both cases leading to the expulsion of the leaving-group. Herein, we provide a physically sound model to rationalize under which circumstances a nucleophile will follow either the aliphatic SN2 or allylic SN2' pathway. Our activation strain analyses expose the underlying physical factors that steer the SN2/SN2' competition and, again, demonstrate that the concepts of a reaction's "characteristic distortivity" and "transition state acidity" provide explanations and design tools for understanding and predicting reactivity trends in organic synthesis.
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Affiliation(s)
- Thomas Hansen
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.,Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.,Departament de Química Inorgànica i Orgànica & IQTCUB, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Pascal Vermeeren
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Lea de Jong
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - F Matthias Bickelhaupt
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.,Institute for Molecules and Materials (IMM), Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Trevor A Hamlin
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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19
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Fornaciari C, Pasini D, Coulembier O. Controlled Oxyanionic Polymerization of Propylene Oxide: Unlocking the Molecular-Weight Limitation by a Soft Nucleophilic Catalysis. Macromol Rapid Commun 2022; 43:e2200424. [PMID: 35686832 DOI: 10.1002/marc.202200424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 05/30/2022] [Indexed: 11/07/2022]
Abstract
The oxyanionic ring-opening polymerization of propylene oxide (PO) from an exogenous alcohol activated with benign (complexed) metal-alkali carboxylates is described. The equimolar mixture of potassium acetate (KOAc) and 18-crown-6 ether (18C6) is demonstrated to be the complex of choice for preparing poly(propylene oxide) (PPO) in a controlled manner. In the presence of 18C6/KOAc, hydrogen-bonded alcohols act as soft nucleophiles promoting the PO SN 2 process at room temperature and in solvent-free conditions while drastically limiting the occurrence of parasitic hydrogen abstraction generally observed during the anionic ROP of PO. The resulting PPO displays predictable and unprecedented molar masses (up to 20 kg mol-1 ) with low dispersities (ĐM < 1.1), rendering the 18C6/KOAc complex the most performing activator for the oxyanionic polymerization of PO reported to date. Preliminary studies on the preparation of block and statistical copolyethers are also reported.
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Affiliation(s)
- Charlotte Fornaciari
- Laboratory of Polymeric and Composite Materials (LPCM), Center of Innovation and Research in Materials and Polymers (CIRMAP), University of Mons, Place du Parc, 20, Mons, 7000, Belgium.,Department of Chemistry, University of Pavia, Viale Taramelli, 10, Pavia, 27100, Italy
| | - Dario Pasini
- Department of Chemistry, University of Pavia, Viale Taramelli, 10, Pavia, 27100, Italy
| | - Olivier Coulembier
- Laboratory of Polymeric and Composite Materials (LPCM), Center of Innovation and Research in Materials and Polymers (CIRMAP), University of Mons, Place du Parc, 20, Mons, 7000, Belgium
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20
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Ji X, Xie J. Proton transfer-induced competing product channels of microsolvated Y -(H 2O) n + CH 3I (Y = F, Cl, Br, I) reactions. Phys Chem Chem Phys 2022; 24:7539-7550. [PMID: 35289813 DOI: 10.1039/d1cp04873b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The potential energy profiles of three proton transfer-involved product channels for the reactions of Y-(H2O)1,2 + CH3I (Y = F, Cl, Br, I) were characterized using the B97-1/ECP/d method. These three channels include the (1) PTCH3 product channel that transfers a proton from methyl to nucleophile, (2) HO--induced nucleophilic substitution (HO--SN2) product channel, and (3) oxide ion substitution (OIS) product channel that gives CH3O- and HY products. The reaction enthalpies and barrier heights follow the order OIS > PTCH3 > HO--SN2 > Y--SN2, and thus HO--SN2 can compete with the most favored Y--SN2 product channel under singly-/doubly-hydrated conditions, while the PTCH3 channel only occurs under high collision energy and the OIS channel is the least probable. All product channels share the same pre-reaction complex, Y-(H2O)n-CH3I, in the entrance of the potential energy profile, signifying the importance of the pre-reaction complex. For HO-/Y--SN2 channels, we considered front-side attack, back-side attack, and halogen-bonded complex mechanisms. Incremental hydration increases the barriers of both HO-/Y--SN2 channels as well as their barrier difference, implying that the HO--SN2 channel becomes less important when further hydrated. Varying the nucleophile Y- from F- to I- also increases the barrier heights and barrier difference, which correlates with the proton affinity of the nucleophiles. Energy decomposition analyses show that both the orbital interaction energy and structural deformation energy of the transition states determine the SN2 barrier change trend with incremental hydration and varying Y-. In brief, this work computes the comprehensive potential energy surfaces of the HO--SN2 and PTCH3 channels and shows how proton transfer affects the microsolvated Y-(H2O)1,2 + CH3I reaction by competing with the traditional Y--SN2 channel.
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Affiliation(s)
- Xiaoyan Ji
- Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China.
| | - Jing Xie
- Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China.
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21
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Hansen T, Sun X, Dalla Tiezza M, van Zeist WJ, Poater J, Hamlin TA, Bickelhaupt FM. C(spn)-X (n = 1-3) Bond Activation by Palladium. Chemistry 2021; 28:e202103953. [PMID: 34958486 PMCID: PMC9306469 DOI: 10.1002/chem.202103953] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Indexed: 11/09/2022]
Abstract
We have studied the palladium-mediated activation of C( sp n )-X bonds (n = 1-3 and X = H, CH 3 , Cl) in archetypal model substrates H 3 C-CH 2 -X, H 2 C=CH-X and HC≡C-X by catalysts PdL n with L n = no ligand, Cl - , and (PH 3 ) 2 , using relativistic density functional theory at ZORA-BLYP/TZ2P. The oxidative addition barrier decreases along this series, even though the strength of the bonds increases going from C( sp 3 )-X, to C( sp 2 )-X, to C( sp )-X. Activation strain and matching energy decomposition analyses reveal that the decreased oxidative addition barrier going from sp 3 to sp 2 to sp , originates from a reduction in the destabilizing steric (Pauli) repulsion between catalyst and substrate. This is the direct consequence of the decreasing coordination number of the carbon atom in C( sp n )-X, which goes from four, to three, to two along this series. The associated net stabilization of the catalyst-substrate interaction dominates the trend in strain energy which indeed becomes more destabilizing along this same series as the bond becomes stronger from C( sp 3 )-X to C( sp )-X.
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Affiliation(s)
- Thomas Hansen
- Vrije Universiteit Amsterdam, Theoretical Chemistry, NETHERLANDS
| | - Xiaobo Sun
- Vrije Universiteit Amsterdam, Theoretical Chemistry, NETHERLANDS
| | | | | | - Jordi Poater
- University of Barcelona: Universitat de Barcelona, Inorganic and organic chemistry, SPAIN
| | - Trevor A Hamlin
- Vrije Universiteit Amsterdam, Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling, De Boelelaan 1083, 1081 HV, Amsterdam, NETHERLANDS
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22
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Hansen T, Roozee JC, Bickelhaupt FM, Hamlin TA. How Solvation Influences the S N2 versus E2 Competition. J Org Chem 2021; 87:1805-1813. [PMID: 34932346 PMCID: PMC8822482 DOI: 10.1021/acs.joc.1c02354] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
We have quantum chemically
investigated how solvation influences
the competition between the SN2 and E2 pathways of the
model F– + C2H5Cl reaction.
The system is solvated in a stepwise manner by going from the gas
phase, then via microsolvation of one to three explicit solvent molecules,
then last to bulk solvation using relativistic density functional
theory at (COSMO)-ZORA-OLYP/QZ4P. We explain how and why the mechanistic
pathway of the system shifts from E2 in the gas phase to SN2 upon strong solvation of the Lewis base (i.e., nucleophile/protophile).
The E2 pathway is preferred under weak solvation of the system by
dichloromethane, whereas a switch in reactivity from E2 to SN2 is observed under strong solvation by water. Our activation strain
and Kohn–Sham molecular orbital analyses reveal that solvation
of the Lewis base has a significant impact on the strength of the
Lewis base. We show how strong solvation furnishes a weaker Lewis
base that is unable to overcome the high characteristic distortivity
associated with the E2 pathway, and thus the SN2 pathway
becomes viable.
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Affiliation(s)
- Thomas Hansen
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.,Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Jasper C Roozee
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - F Matthias Bickelhaupt
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.,Institute for Molecules and Materials (IMM), Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Trevor A Hamlin
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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23
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Corbin N, Yang DT, Lazouski N, Steinberg K, Manthiram K. Suppressing carboxylate nucleophilicity with inorganic salts enables selective electrocarboxylation without sacrificial anodes. Chem Sci 2021; 12:12365-12376. [PMID: 34603666 PMCID: PMC8480422 DOI: 10.1039/d1sc02413b] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 09/23/2021] [Accepted: 08/05/2021] [Indexed: 01/02/2023] Open
Abstract
Although electrocarboxylation reactions use CO2 as a renewable synthon and can incorporate renewable electricity as a driving force, the overall sustainability and practicality of this process is limited by the use of sacrificial anodes such as magnesium and aluminum. Replacing these anodes for the carboxylation of organic halides is not trivial because the cations produced from their oxidation inhibit a variety of undesired nucleophilic reactions that form esters, carbonates, and alcohols. Herein, a strategy to maintain selectivity without a sacrificial anode is developed by adding a salt with an inorganic cation that blocks nucleophilic reactions. Using anhydrous MgBr2 as a low-cost, soluble source of Mg2+ cations, carboxylation of a variety of aliphatic, benzylic, and aromatic halides was achieved with moderate to good (34-78%) yields without a sacrificial anode. Moreover, the yields from the sacrificial-anode-free process were often comparable or better than those from a traditional sacrificial-anode process. Examining a wide variety of substrates shows a correlation between known nucleophilic susceptibilities of carbon-halide bonds and selectivity loss in the absence of a Mg2+ source. The carboxylate anion product was also discovered to mitigate cathodic passivation by insoluble carbonates produced as byproducts from concomitant CO2 reduction to CO, although this protection can eventually become insufficient when sacrificial anodes are used. These results are a key step toward sustainable and practical carboxylation by providing an electrolyte design guideline to obviate the need for sacrificial anodes.
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Affiliation(s)
- Nathan Corbin
- Department of Chemical Engineering, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge Massachusetts 02139 USA
| | - Deng-Tao Yang
- Department of Chemical Engineering, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge Massachusetts 02139 USA
| | - Nikifar Lazouski
- Department of Chemical Engineering, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge Massachusetts 02139 USA
| | - Katherine Steinberg
- Department of Chemical Engineering, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge Massachusetts 02139 USA
| | - Karthish Manthiram
- Department of Chemical Engineering, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge Massachusetts 02139 USA
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24
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Vermeeren P, Hamlin TA, Bickelhaupt FM. Origin of asynchronicity in Diels-Alder reactions. Phys Chem Chem Phys 2021; 23:20095-20106. [PMID: 34499069 PMCID: PMC8457343 DOI: 10.1039/d1cp02456f] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 09/02/2021] [Indexed: 02/02/2023]
Abstract
Asynchronicity in Diels-Alder reactions plays a crucial role in determining the height of the reaction barrier. Currently, the origin of asynchronicity is ascribed to the stronger orbital interaction between the diene and the terminal carbon of an asymmetric dienophile, which shortens the corresponding newly formed C-C bond and hence induces asynchronicity in the reaction. Here, we show, using the activation strain model and Kohn-Sham molecular orbital theory at ZORA-BP86/TZ2P, that this rationale behind asynchronicity is incorrect. We, in fact, found that following a more asynchronous reaction mode costs favorable HOMO-LUMO orbital overlap and, therefore, weakens (not strengthens) these orbital interactions. Instead, it is the Pauli repulsion that induces asynchronicity in Diels-Alder reactions. An asynchronous reaction pathway also lowers repulsive occupied-occupied orbital overlap which, therefore, reduces the unfavorable Pauli repulsion. As soon as this mechanism of reducing Pauli repulsion dominates, the reaction begins to deviate from synchronicity and adopts an asynchronous mode. The eventual degree of asynchronicity, as observed in the transition state of a Diels-Alder reaction, is ultimately achieved when the gain in stability, as a response to the reduced Pauli repulsion, balances with the loss of favorable orbital interactions.
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Affiliation(s)
- Pascal Vermeeren
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
| | - Trevor A Hamlin
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
| | - F Matthias Bickelhaupt
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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25
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Hansen T, Vermeeren P, Bickelhaupt FM, Hamlin TA. Origin of the α‐Effect in S
N
2 Reactions. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202106053] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Thomas Hansen
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands
- Leiden Institute of Chemistry Leiden University Einsteinweg 55 2333 CC Leiden The Netherlands
| | - Pascal Vermeeren
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands
| | - F. Matthias Bickelhaupt
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands
- Institute for Molecules and Materials Radboud University Heyendaalseweg 135 6525 AJ Nijmegen The Netherlands
| | - Trevor A. Hamlin
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands
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26
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Hansen T, Vermeeren P, Bickelhaupt FM, Hamlin TA. Origin of the α-Effect in S N 2 Reactions. Angew Chem Int Ed Engl 2021; 60:20840-20848. [PMID: 34087047 PMCID: PMC8518820 DOI: 10.1002/anie.202106053] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 05/27/2021] [Indexed: 11/07/2022]
Abstract
The α-effect is a term used to explain the dramatically enhanced reactivity of α-nucleophiles (R-Y-X:- ) compared to their parent normal nucleophile (R-X:- ) by deviating from the classical Brønsted-type reactivity-basicity relationship. The exact origin of this effect is, however, still heavily under debate. In this work, we have quantum chemically analyzed the α-effect of a set of anionic nucleophiles, including O-, N- and S-based normal and α-nucleophiles, participating in an SN 2 reaction with ethyl chloride using relativistic density functional theory at ZORA-OLYP/QZ4P. Our activation strain and Kohn-Sham molecular orbital analyses identified two criteria an α-nucleophile needs to fulfill in order to show α-effect: (i) a small HOMO lobe on the nucleophilic center, pointing towards the substrate, to reduce the repulsive occupied-occupied orbital overlap and hence (steric) Pauli repulsion with the substrate; and (ii) a sufficiently high energy HOMO to overcome the loss of favorable HOMO-LUMO orbital overlap with the substrate, as a consequence of the first criterion, by reducing the HOMO-LUMO orbital energy gap. If one of these two criteria is not fulfilled, one can expect no α-effect or inverse α-effect.
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Affiliation(s)
- Thomas Hansen
- Department of Theoretical ChemistryAmsterdam Institute of Molecular and Life Sciences (AIMMS)Amsterdam Center for Multiscale Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdamThe Netherlands
- Leiden Institute of ChemistryLeiden UniversityEinsteinweg 552333 CCLeidenThe Netherlands
| | - Pascal Vermeeren
- Department of Theoretical ChemistryAmsterdam Institute of Molecular and Life Sciences (AIMMS)Amsterdam Center for Multiscale Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdamThe Netherlands
| | - F. Matthias Bickelhaupt
- Department of Theoretical ChemistryAmsterdam Institute of Molecular and Life Sciences (AIMMS)Amsterdam Center for Multiscale Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdamThe Netherlands
- Institute for Molecules and MaterialsRadboud UniversityHeyendaalseweg 1356525 AJNijmegenThe Netherlands
| | - Trevor A. Hamlin
- Department of Theoretical ChemistryAmsterdam Institute of Molecular and Life Sciences (AIMMS)Amsterdam Center for Multiscale Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdamThe Netherlands
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27
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Alkorta I, Elguero J. The SN2 reaction and its relationship with the Walden inversion, the Finkelstein and Menshutkin reactions together with theoretical calculations for the Finkelstein reaction. Struct Chem 2021. [DOI: 10.1007/s11224-021-01805-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
AbstractThis communication gives an overview of the relationships between four reactions that although related were not always perceived as such: SN2, Walden, Finkelstein, and Menshutkin. Binary interactions (SN2 & Walden, SN2 & Menshutkin, SN2 & Finkelstein, Walden & Menshutkin, Walden & Finkelstein, Menshutkin & Finkelstein) were reported. Carbon, silicon, nitrogen, and phosphorus as central atoms and fluorides, chlorides, bromides, and iodides as lateral atoms were considered. Theoretical calculations provide Gibbs free energies that were analyzed with linear models to obtain the halide contributions. The M06-2x DFT computational method and the 6-311++G(d,p) basis set have been used for all atoms except for iodine where the effective core potential def2-TZVP basis set was used. Concerning the central atom pairs, carbon/silicon vs. nitrogen/phosphorus, we reported here for the first time that the effect of valence expansion was known for Si but not for P. Concerning the lateral halogen atoms, some empirical models including the interaction between F and I as entering and leaving groups explain the Gibbs free energies.
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28
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Stuyver T, Shaik S. Resolving Entangled Reactivity Modes through External Electric Fields and Substitution: Application to E 2/S N2 Reactions. J Org Chem 2021; 86:9030-9039. [PMID: 34152765 DOI: 10.1021/acs.joc.1c01010] [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
In this study, we explore strategies to resolve entangled reactivity modes. More specifically, we consider the competition between SN2 and E2 reaction pathways for alkyl halides and nucleophiles/bases. We first demonstrate that the emergence of an E2-preference is associated with an enhancement of the magnitude of the resonance stabilization in the transition-state (TS) region, resulting from the improved mixing of electrostatically stabilized valence bond structures into the TS wavefunction. Subsequently, we show that the TS resonance energy can be tuned selectively and rationally either through the application of an oriented external electric field directed along the C-C axis of the alkyl halide or through a regular substitution approach of the C-C moiety. We end our study by demonstrating that the insights gained from our analysis enable one to rationalize the main reactivity trends emerging from a recently published large database of competing SN2 and E2 reaction pathways.
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Affiliation(s)
- Thijs Stuyver
- Department of Organic Chemistry, The Hebrew University, Jerusalem 91904, Israel
| | - Sason Shaik
- Department of Organic Chemistry, The Hebrew University, Jerusalem 91904, Israel
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29
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Vermeeren P, Hamlin TA, Bickelhaupt FM. Chemical reactivity from an activation strain perspective. Chem Commun (Camb) 2021; 57:5880-5896. [PMID: 34075969 PMCID: PMC8204247 DOI: 10.1039/d1cc02042k] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 05/25/2021] [Indexed: 12/14/2022]
Abstract
Chemical reactions are ubiquitous in the universe, they are at the core of life, and they are essential for industrial processes. The drive for a deep understanding of how something occurs, in this case, the mechanism of a chemical reaction and the factors controlling its reactivity, is intrinsically valuable and an innate quality of humans. The level of insight and degree of understanding afforded by computational chemistry cannot be understated. The activation strain model is one of the most powerful tools in our arsenal to obtain unparalleled insight into reactivity. The relative energy of interacting reactants is evaluated along a reaction energy profile and related to the rigidity of the reactants' molecular structure and the strength of the stabilizing interactions between the deformed reactants: ΔE(ζ) = ΔEstrain(ζ) + ΔEint(ζ). Owing to the connectedness between the activation strain model and Kohn-Sham molecular orbital theory, one is able to obtain a causal relationship between both the sterics and electronics of the reactants and their mutual reactivity. Only when this is accomplished one can eclipse the phenomenological explanations that are commonplace in the literature and textbooks and begin to rationally tune and optimize chemical transformations. We showcase how the activation strain model is the ideal tool to elucidate fundamental organic reactions, the activation of small molecules by metallylenes, and the cycloaddition reactivity of cyclic diene- and dipolarophiles.
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Affiliation(s)
- Pascal Vermeeren
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
| | - Trevor A Hamlin
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
| | - F Matthias Bickelhaupt
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands. and Institute for Molecules and Materials (IMM), Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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30
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Tasi DA, Tokaji C, Czakó G. A benchmark ab initio study of the complex potential energy surfaces of the OH - + CH 3CH 2Y [Y = F, Cl, Br, I] reactions. Phys Chem Chem Phys 2021; 23:13526-13534. [PMID: 34132273 DOI: 10.1039/d1cp01303c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We provide the first benchmark characterization of the OH- + CH3CH2Y [Y = F, Cl, Br, I] reactions utilizing the high-level explicitly-correlated CCSD(T)-F12b method with the aug-cc-pVnZ [n = 2(D), 3(T), 4(Q)] basis sets. We explore and analyze the stationary points of the elimination (E2) and substitution (SN2) reactions, including anti-E2, syn-E2, back-side attack, front-side attack, and double inversion. In all cases, SN2 is thermodynamically more preferred than E2. In the entrance channel of SN2 a significant front-side complex formation is revealed, and in the product channel the global minimum of the title reactions is obtained at the hydrogen-bonded CH3CH2OHY- complex. Similar to the OH- + CH3Y reactions, double inversion can proceed via a notably lower-energy pathway than front-side attack, moreover, for Y = I double inversion becomes barrier-less. For the transition state of the anti-E2, a prominent ZPE effect emerges, giving an opportunity for a kinetically more favored pathway than back-side attack. In addition to SN2 and E2, other possible product channels are considered, and in most cases, the benchmark reaction enthalpies are in excellent agreement with the experimental data.
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Affiliation(s)
- Domonkos A Tasi
- MTA-SZTE Lendület Computational Reaction Dynamics Research Group, Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary.
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31
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Vermeeren P, van Zeist WJ, Hamlin TA, Fonseca Guerra C, Bickelhaupt FM. Not Carbon s-p Hybridization, but Coordination Number Determines C-H and C-C Bond Length. Chemistry 2021; 27:7074-7079. [PMID: 33513281 PMCID: PMC8248318 DOI: 10.1002/chem.202004653] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 01/26/2021] [Indexed: 11/26/2022]
Abstract
A fundamental and ubiquitous phenomenon in chemistry is the contraction of both C−H and C−C bonds as the carbon atoms involved vary, in s–p hybridization, along sp3 to sp2 to sp. Our quantum chemical bonding analyses based on Kohn–Sham molecular orbital theory show that the generally accepted rationale behind this trend is incorrect. Inspection of the molecular orbitals and their corresponding orbital overlaps reveals that the above‐mentioned shortening in C−H and C−C bonds is not determined by an increasing amount of s‐character at the carbon atom in these bonds. Instead, we establish that this structural trend is caused by a diminishing steric (Pauli) repulsion between substituents around the pertinent carbon atom, as the coordination number decreases along sp3 to sp2 to sp.
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Affiliation(s)
- Pascal Vermeeren
- Department of Theoretical Chemistry, Amsterdam Institute of, Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale, Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam, The Netherlands
| | - Willem-Jan van Zeist
- Department of Theoretical Chemistry, Amsterdam Institute of, Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale, Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam, The Netherlands
| | - Trevor A Hamlin
- Department of Theoretical Chemistry, Amsterdam Institute of, Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale, Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam, The Netherlands
| | - Célia Fonseca Guerra
- Department of Theoretical Chemistry, Amsterdam Institute of, Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale, Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam, The Netherlands.,Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands
| | - F Matthias Bickelhaupt
- Department of Theoretical Chemistry, Amsterdam Institute of, Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale, Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam, The Netherlands.,Institute for Molecules and Materials (IMM), Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
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32
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Hansen T, Vermeeren P, Yoshisada R, Filippov DV, van der Marel GA, Codée JDC, Hamlin TA. How Lewis Acids Catalyze Ring-Openings of Cyclohexene Oxide. J Org Chem 2021; 86:3565-3573. [PMID: 33538169 PMCID: PMC7901664 DOI: 10.1021/acs.joc.0c02955] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Indexed: 11/29/2022]
Abstract
We have quantum chemically studied the Lewis acid-catalyzed epoxide ring-opening reaction of cyclohexene epoxide by MeZH (Z = O, S, and NH) using relativistic dispersion-corrected density functional theory. We found that the reaction barrier of the Lewis acid-catalyzed epoxide ring-opening reactions decreases upon ascending in group 1 along the series Cs+ > Rb+ > K+ > Na+ > Li+ > H+. Our activation strain and Kohn-Sham molecular orbital analyses reveal that the enhanced reactivity of the Lewis acid-catalyzed ring-opening reaction is caused by the reduced steric (Pauli) repulsion between the filled orbitals of the epoxide and the nucleophile, as the Lewis acid polarizes the filled orbitals of the epoxide more efficiently away from the incoming nucleophile. Furthermore, we established that the regioselectivity of these ring-opening reactions is, aside from the "classical" strain control, also dictated by a hitherto unknown mechanism, namely, the steric (Pauli) repulsion between the nucleophile and the substrate, which could be traced back to the asymmetric orbital density on the epoxide. In all, this work again demonstrates that the concept of Pauli-lowering catalysis is a general phenomenon.
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Affiliation(s)
- Thomas Hansen
- Department of Theoretical Chemistry, Amsterdam
Institute of Molecular and Life Sciences (AIMSS), Amsterdam Center for Multiscale Modeling
(ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081
HV Amsterdam, The Netherlands
- Leiden Institute of Chemistry, Leiden
University, Einsteinweg 55, 2333 CC Leiden, The
Netherlands
| | - Pascal Vermeeren
- Department of Theoretical Chemistry, Amsterdam
Institute of Molecular and Life Sciences (AIMSS), Amsterdam Center for Multiscale Modeling
(ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081
HV Amsterdam, The Netherlands
| | - Ryoji Yoshisada
- Leiden Institute of Chemistry, Leiden
University, Einsteinweg 55, 2333 CC Leiden, The
Netherlands
| | - Dmitri V. Filippov
- Leiden Institute of Chemistry, Leiden
University, Einsteinweg 55, 2333 CC Leiden, The
Netherlands
| | | | - Jeroen D. C. Codée
- Leiden Institute of Chemistry, Leiden
University, Einsteinweg 55, 2333 CC Leiden, The
Netherlands
| | - Trevor A. Hamlin
- Department of Theoretical Chemistry, Amsterdam
Institute of Molecular and Life Sciences (AIMSS), Amsterdam Center for Multiscale Modeling
(ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081
HV Amsterdam, The Netherlands
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33
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Vermeeren P, Hansen T, Jansen P, Swart M, Hamlin TA, Bickelhaupt FM. A Unified Framework for Understanding Nucleophilicity and Protophilicity in the S N 2/E2 Competition. Chemistry 2020; 26:15538-15548. [PMID: 32866336 PMCID: PMC7756690 DOI: 10.1002/chem.202003831] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Indexed: 11/11/2022]
Abstract
The concepts of nucleophilicity and protophilicity are fundamental and ubiquitous in chemistry. A case in point is bimolecular nucleophilic substitution (SN 2) and base-induced elimination (E2). A Lewis base acting as a strong nucleophile is needed for SN 2 reactions, whereas a Lewis base acting as a strong protophile (i.e., base) is required for E2 reactions. A complicating factor is, however, the fact that a good nucleophile is often a strong protophile. Nevertheless, a sound, physical model that explains, in a transparent manner, when an electron-rich Lewis base acts as a protophile or a nucleophile, which is not just phenomenological, is currently lacking in the literature. To address this fundamental question, the potential energy surfaces of the SN 2 and E2 reactions of X- +C2 H5 Y model systems with X, Y = F, Cl, Br, I, and At, are explored by using relativistic density functional theory at ZORA-OLYP/TZ2P. These explorations have yielded a consistent overview of reactivity trends over a wide range in reactivity and pathways. Activation strain analyses of these reactions reveal the factors that determine the shape of the potential energy surfaces and hence govern the propensity of the Lewis base to act as a nucleophile or protophile. The concepts of "characteristic distortivity" and "transition state acidity" of a reaction are introduced, which have the potential to enable chemists to better understand and design reactions for synthesis.
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Affiliation(s)
- Pascal Vermeeren
- Department of Theoretical ChemistryAmsterdam Institute of, Molecular and Life Sciences (AIMMS)Amsterdam Center for Multiscale, Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081HVAmsterdamThe Netherlands
| | - Thomas Hansen
- Department of Theoretical ChemistryAmsterdam Institute of, Molecular and Life Sciences (AIMMS)Amsterdam Center for Multiscale, Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081HVAmsterdamThe Netherlands
- Leiden Institute of ChemistryLeiden UniversityEinsteinweg 55, 2333CCLeidenThe Netherlands
| | - Paul Jansen
- Department of Theoretical ChemistryAmsterdam Institute of, Molecular and Life Sciences (AIMMS)Amsterdam Center for Multiscale, Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081HVAmsterdamThe Netherlands
- Laboratory of Physical ChemistryETH ZurichVladimir-Prelog-Weg 28093ZurichSwitzerland
| | - Marcel Swart
- ICREAPg. Lluís Companys 2308010BarcelonaSpain
- IQCC & Dept. QuímicaUniversitat de GironaCampus Montilivi (Ciències)17003GironaSpain
| | - Trevor A. Hamlin
- Department of Theoretical ChemistryAmsterdam Institute of, Molecular and Life Sciences (AIMMS)Amsterdam Center for Multiscale, Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081HVAmsterdamThe Netherlands
| | - F. Matthias Bickelhaupt
- Department of Theoretical ChemistryAmsterdam Institute of, Molecular and Life Sciences (AIMMS)Amsterdam Center for Multiscale, Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081HVAmsterdamThe Netherlands
- Institute for Molecules and MaterialsRadboud UniversityHeyendaalseweg 1356525AJNijmegenThe Netherlands
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34
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Vermeeren P, Hansen T, Grasser M, Silva DR, Hamlin TA, Bickelhaupt FM. S N2 versus E2 Competition of F - and PH 2- Revisited. J Org Chem 2020; 85:14087-14093. [PMID: 33079542 PMCID: PMC7656514 DOI: 10.1021/acs.joc.0c02112] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have quantum chemically analyzed the competition between the bimolecular nucleophilic substitution (SN2) and base-induced elimination (E2) pathways for F- + CH3CH2Cl and PH2- + CH3CH2Cl using the activation strain model and Kohn-Sham molecular orbital theory at ZORA-OLYP/QZ4P. Herein, we correct an earlier study that intuitively attributed the mechanistic preferences of F- and PH2-, i.e., E2 and SN2, respectively, to a supposedly unfavorable shift in the polarity of the abstracted β-proton along the PH2--induced E2 pathway while claiming that ″...no correlation between the thermodynamic basicity and E2 rate should be expected.″ Our analyses, however, unequivocally show that it is simply the 6 kcal mol-1 higher proton affinity of F- that enables this base to engage in a more stabilizing orbital interaction with CH3CH2Cl and hence to preferentially react via the E2 pathway, despite the higher characteristic distortivity (more destabilizing activation strain) associated with this pathway. On the other hand, the less basic PH2- has a weaker stabilizing interaction with CH3CH2Cl and is, therefore, unable to overcome the characteristic distortivity of the E2 pathway. Therefore, the mechanistic preference of PH2- is steered to the SN2 reaction channel (less-destabilizing activation strain).
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Affiliation(s)
- Pascal Vermeeren
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Thomas Hansen
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.,Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Maxime Grasser
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Daniela Rodrigues Silva
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.,Departamento de Quı́mica, Universidade Federal de Lavras, Lavras, Minas Gerais 37200-900, Brazil
| | - Trevor A Hamlin
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - F Matthias Bickelhaupt
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.,Institute for Molecules and Materials (IMM), Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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