1
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Zhang X, Lefebvre PL, Harvey JN. Effect of solvent motions on the dynamics of the Diels-Alder reaction. Phys Chem Chem Phys 2021; 24:1120-1130. [PMID: 34928279 DOI: 10.1039/d1cp05272a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
How solvent motions affect the dynamics of chemical reactions in which the solute undergoes a substantial shape change is a fundamental but elusive issue. This work utilizes reactive simulation and Grote-Hynes theory to explore the effect of solvent motions on the dynamics of the Diels-Alder reaction (in the reverse direction, this reaction involves very substantial solute expansion) in aprotic solvents. The results reveal that the solvent environment is not sufficiently constraining to influence transition state passage dynamics, with the calculated transmission coefficients being close to unity. Even when solvent motions are suppressed or artificially slowed down, the solvent only affects the reaction dynamics in the transition state region to a very small extent. The only notable effect of solvent occurs far from the transition state region and corresponds to caging of the reactants within the reactant well.
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Affiliation(s)
- Xiaoyong Zhang
- Theoretical and Computational Chemistry, Department of Chemistry, KU Leuven Celestijnenlaan 200F, 3001, Leuven, Belgium.
| | - Pierre-Louis Lefebvre
- Theoretical and Computational Chemistry, Department of Chemistry, KU Leuven Celestijnenlaan 200F, 3001, Leuven, Belgium. .,Quantum Theory Project, Departments of Chemistry and Physics, University of Florida, Gainesville, Florida 32611, USA
| | - Jeremy N Harvey
- Theoretical and Computational Chemistry, Department of Chemistry, KU Leuven Celestijnenlaan 200F, 3001, Leuven, Belgium.
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2
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Rohrbach S, Smith AJ, Pang JH, Poole DL, Tuttle T, Chiba S, Murphy JA. Concerted Nucleophilic Aromatic Substitution Reactions. Angew Chem Int Ed Engl 2019; 58:16368-16388. [PMID: 30990931 PMCID: PMC6899550 DOI: 10.1002/anie.201902216] [Citation(s) in RCA: 129] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/11/2019] [Indexed: 12/31/2022]
Abstract
Recent developments in experimental and computational chemistry have identified a rapidly growing class of nucleophilic aromatic substitutions that proceed by concerted (cSN Ar) rather than classical, two-step, SN Ar mechanisms. Whereas traditional SN Ar reactions require substantial activation of the aromatic ring by electron-withdrawing substituents, such activating groups are not mandatory in the concerted pathways.
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Affiliation(s)
- Simon Rohrbach
- Department of Pure and Applied ChemistryUniversity of Strathclyde295 Cathedral StreetGlasgowG1 1XLUK
| | - Andrew J. Smith
- Department of Pure and Applied ChemistryUniversity of Strathclyde295 Cathedral StreetGlasgowG1 1XLUK
| | - Jia Hao Pang
- Division of Chemistry and Biological ChemistrySchool of Physical and Mathematical SciencesNanyang Technological UniversitySingapore637371Singapore
| | - Darren L. Poole
- GlaxoSmithKline Medicines Research CentreGunnels Wood RoadStevenageSG1 2NYUK
| | - Tell Tuttle
- Department of Pure and Applied ChemistryUniversity of Strathclyde295 Cathedral StreetGlasgowG1 1XLUK
| | - Shunsuke Chiba
- Division of Chemistry and Biological ChemistrySchool of Physical and Mathematical SciencesNanyang Technological UniversitySingapore637371Singapore
| | - John A. Murphy
- Department of Pure and Applied ChemistryUniversity of Strathclyde295 Cathedral StreetGlasgowG1 1XLUK
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3
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Rohrbach S, Smith AJ, Pang JH, Poole DL, Tuttle T, Chiba S, Murphy JA. Konzertierte nukleophile aromatische Substitutionen. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201902216] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Simon Rohrbach
- Department of Pure and Applied ChemistryUniversity of Strathclyde 295 Cathedral Street Glasgow G1 1XL Großbritannien
| | - Andrew J. Smith
- Department of Pure and Applied ChemistryUniversity of Strathclyde 295 Cathedral Street Glasgow G1 1XL Großbritannien
| | - Jia Hao Pang
- Division of Chemistry and Biological ChemistrySchool of Physical and Mathematical SciencesNanyang Technological University Singapore 637371 Singapur
| | - Darren L. Poole
- GlaxoSmithKline Medicines Research Centre Gunnels Wood Road Stevenage SG1 2NY Großbritannien
| | - Tell Tuttle
- Department of Pure and Applied ChemistryUniversity of Strathclyde 295 Cathedral Street Glasgow G1 1XL Großbritannien
| | - Shunsuke Chiba
- Division of Chemistry and Biological ChemistrySchool of Physical and Mathematical SciencesNanyang Technological University Singapore 637371 Singapur
| | - John A. Murphy
- Department of Pure and Applied ChemistryUniversity of Strathclyde 295 Cathedral Street Glasgow G1 1XL Großbritannien
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4
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Ram RN, Singh V. Diazotisation of aromatic amines and solvolysis of diazonium salts in ethylene glycol ethers. JOURNAL OF CHEMICAL RESEARCH 2019. [DOI: 10.3184/030823406780199848] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Aniline and unhindered alkyl-substituted anilines undergo solvolysis in dioxane and DME saturated with dry hydrogen chloride on diazotisation with isoamyl nitrite to give 2-(2-chloroethoxy)ethyl aryl ethers and 2-methoxyethyl aryl ethers respectively in 36-47% yields. 2,6-Dialkyl-substituted anilines give the corresponding chloro compounds as the major product along with the aryl ethers in lower yields. Diazotisation of aniline in ethylene glycol and monomethyl ethers of ethylene glycol and diethylene glycol gave the corresponding alcoholysis products in low yields. The solvolysis of aniline did not occur on diazotisation in diethyl ether or THF.
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Affiliation(s)
- Ram N. Ram
- Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi-110016, India
| | - Virinder Singh
- Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi-110016, India
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5
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Mohy El Dine T, Sadek O, Gras E, Perrin DM. Expanding the Balz-Schiemann Reaction: Organotrifluoroborates Serve as Competent Sources of Fluoride Ion for Fluoro-Dediazoniation. Chemistry 2018; 24:14933-14937. [PMID: 30006957 DOI: 10.1002/chem.201803575] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Indexed: 12/18/2022]
Abstract
The Balz-Schiemann reaction endures as a method for the preparation of (hetero)aryl fluorides yet is eschewed due to the need for harsh conditions or high temperatures along with the need to isolate potentially explosive diazonium salts. In a departure from these conditions, we show that various organotrifluoroborates (RBF3 - s) may serve as fluoride ion sources for solution-phase fluoro-dediazoniation in organic solvents under mild conditions. This methodology was successfully extended to a one-pot process obviating aryl diazonium salt isolation. Sterically hindered (hetero)anilines are fluorinated under unprecedentedly mild conditions in good-to-excellent yields. Taken together, this work expands the repertoire of RBF3 - s to act as fluorine ion sources in an update to the classic Balz-Schiemann reaction.
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Affiliation(s)
- Tharwat Mohy El Dine
- Chemistry Department, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada
| | - Omar Sadek
- Chemistry Department, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada.,LCC-CNRS, Université de Toulouse, 205 route de Narbonne, BP 44099 31077, Toulouse Ce, dex 4, France
| | - Emmanuel Gras
- LCC-CNRS, Université de Toulouse, 205 route de Narbonne, BP 44099 31077, Toulouse Ce, dex 4, France
| | - David M Perrin
- Chemistry Department, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada
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6
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7
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Masumoto Y, Miyamoto K, Iuchi T, Ochiai M, Hirano K, Saito T, Wang C, Uchiyama M. Mechanistic Study on Aryl-Exchange Reaction of Diaryl-λ 3-iodane with Aryl Iodide. J Org Chem 2018; 83:289-295. [PMID: 29183123 DOI: 10.1021/acs.joc.7b02701] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Because of its hyper-leaving ability, as well as its strong oxidizing ability, diaryl(triflato)-λ3-iodane transfers one of the aryl groups to iodoarenes simply upon gentle heating (>85 °C) in nonpolar solvents. We have performed an in-depth mechanistic study of this unusual aryl transfer reaction. A combination of experimental (product analysis, kinetic study, and substituent effects) and density functional theoretical approaches revealed that the reaction proceeds through a concerted bimolecular transition state, in which ipso-carbon binds loosely to both iodine centers. We also evaluated electronic effects on the thermodynamic stability of diaryl-λ3-iodanes.
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Affiliation(s)
- Yui Masumoto
- Graduate School of Pharmaceutical Sciences, The University of Tokyo , 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan.,Elements Chemistry Laboratory, RIKEN, and Advanced Elements Chemistry Research Team, RIKEN Center for Sustainable Resource Science (CSRS) , Wako-shi, Saitama 351-0198, Japan
| | - Kazunori Miyamoto
- Graduate School of Pharmaceutical Sciences, The University of Tokyo , 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takuto Iuchi
- Graduate School of Pharmaceutical Sciences, Tokushima University , 1-78 Shomachi, Tokushima 770-8505, Japan
| | - Masahito Ochiai
- Graduate School of Pharmaceutical Sciences, Tokushima University , 1-78 Shomachi, Tokushima 770-8505, Japan
| | - Keiichi Hirano
- Graduate School of Pharmaceutical Sciences, The University of Tokyo , 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan
| | - Tatsuo Saito
- Graduate School of Pharmaceutical Sciences, The University of Tokyo , 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan
| | - Chao Wang
- Graduate School of Pharmaceutical Sciences, The University of Tokyo , 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan
| | - Masanobu Uchiyama
- Graduate School of Pharmaceutical Sciences, The University of Tokyo , 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan.,Elements Chemistry Laboratory, RIKEN, and Advanced Elements Chemistry Research Team, RIKEN Center for Sustainable Resource Science (CSRS) , Wako-shi, Saitama 351-0198, Japan
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8
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Doubleday C, Armas R, Walker D, Cosgriff CV, Greer EM. Heavy-Atom Tunneling Calculations in Thirteen Organic Reactions: Tunneling Contributions are Substantial, and Bell's Formula Closely Approximates Multidimensional Tunneling at ≥250 K. Angew Chem Int Ed Engl 2017; 56:13099-13102. [PMID: 28881399 DOI: 10.1002/anie.201708489] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Indexed: 11/08/2022]
Abstract
Multidimensional tunneling calculations are carried out for 13 reactions, to test the scope of heavy-atom tunneling in organic chemistry, and to check the accuracy of one-dimensional tunneling models. The reactions include pericyclic, cycloaromatization, radical cyclization and ring opening, and SN 2. When compared at the temperatures that give the same effective rate constant of 3×10-5 s-1 , tunneling accounts for 25-95 % of the rate in 8 of the 13 reactions. Values of transmission coefficients predicted by Bell's formula, κBell , agree well with multidimensional tunneling (canonical variational transition state theory with small curvature tunneling), κSCT . Mean unsigned deviations of κBell vs. κSCT are 0.08, 0.04, 0.02 at 250, 300 and 400 K. This suggests that κBell is a useful first choice for predicting transmission coefficients in heavy-atom tunnelling.
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Affiliation(s)
| | | | | | | | - Edyta M Greer
- Baruch College of the City University of New York, New York, NY, USA
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9
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Doubleday C, Armas R, Walker D, Cosgriff CV, Greer EM. Heavy‐Atom Tunneling Calculations in Thirteen Organic Reactions: Tunneling Contributions are Substantial, and Bell's Formula Closely Approximates Multidimensional Tunneling at ≥250 K. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201708489] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | - Edyta M. Greer
- Baruch College of the City University of New York New York NY USA
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10
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Nieves-Quinones Y, Singleton DA. Dynamics and the Regiochemistry of Nitration of Toluene. J Am Chem Soc 2016; 138:15167-15176. [PMID: 27794598 DOI: 10.1021/jacs.6b07328] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The regiochemistry of the nitration of toluene by NO2+BF4- in dichloromethane is accurately predicted from trajectories in explicit solvent. Simpler models and approaches based on transition state theory fail to account for the selectivity. Potential of mean force calculations find no free-energy barrier for reaction of the toluene/NO2+BF4- encounter complex, yet the trajectories require an extraordinary 3 ps to descend an exergonic slope. The selectivity is decided late in long trajectories because their completion requires solvent and counterion reorganization. The normal descriptive understanding of the regiochemistry based on transition-state energies is unsupported.
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Affiliation(s)
- Yexenia Nieves-Quinones
- Department of Chemistry, Texas A&M University , 3255 TAMU, College Station, Texas 77843, United States
| | - Daniel A Singleton
- Department of Chemistry, Texas A&M University , 3255 TAMU, College Station, Texas 77843, United States
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11
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Carpenter BK, Harvey JN, Orr-Ewing AJ. The Study of Reactive Intermediates in Condensed Phases. J Am Chem Soc 2016; 138:4695-705. [DOI: 10.1021/jacs.6b01761] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Barry K. Carpenter
- School
of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, U.K
| | - Jeremy N. Harvey
- Department
of Chemistry, KU Leuven, Celestijnen Laan 200F, B-3001 Heverlee, Belgium
| | - Andrew J. Orr-Ewing
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K
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12
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Li L, Lelyveld VS, Prywes N, Szostak JW. Experimental and Computational Evidence for a Loose Transition State in Phosphoroimidazolide Hydrolysis. J Am Chem Soc 2016; 138:3986-9. [PMID: 26974265 PMCID: PMC7547882 DOI: 10.1021/jacs.6b00784] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phosphoroimidazolides play a critical role in several enzymatic phosphoryl transfer reactions and have been studied extensively as activated monomers for nonenzymatic nucleic acid replication, but the detailed mechanisms of these phosphoryl transfer reactions remain elusive. Some aspects of the mechanism can be deduced by studying the hydrolysis reaction, a simpler system that is amenable to a thorough mechanistic treatment. Here we characterize the transition state of phosphoroimidazolide hydrolysis by kinetic isotope effect (KIE) and linear free energy relationship (LFER) measurements, and theoretical calculations. The KIE and LFER observations are best explained by calculated loose transition structures with extensive scissile bond cleavage. These three-dimensional models of the transition state provide the basis for future mechanistic investigations of phosphoroimidazolide reactions.
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Affiliation(s)
- Li Li
- Howard Hughes Medical Institute, Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital , Boston, Massachusetts 02114, United States
| | - Victor S Lelyveld
- Howard Hughes Medical Institute, Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital , Boston, Massachusetts 02114, United States
| | - Noam Prywes
- Howard Hughes Medical Institute, Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital , Boston, Massachusetts 02114, United States
| | - Jack W Szostak
- Howard Hughes Medical Institute, Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital , Boston, Massachusetts 02114, United States
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13
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Joshi SM, de Cózar A, Gómez-Vallejo V, Koziorowski J, Llop J, Cossío FP. Synthesis of radiolabelled aryl azides from diazonium salts: experimental and computational results permit the identification of the preferred mechanism. Chem Commun (Camb) 2016; 51:8954-7. [PMID: 25929958 DOI: 10.1039/c5cc01913c] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Experimental and computational studies on the formation of aryl azides from the corresponding diazonium salts support a stepwise mechanism via acyclic zwitterionic intermediates. The low energy barriers associated with both transition structures are compatible with very fast and efficient processes, thus making this method suitable for the chemical synthesis of radiolabelled aryl azides.
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Affiliation(s)
- Sameer M Joshi
- Radiochemistry and Nuclear Imaging, CIC biomaGUNE, Paseo Miramón 182, Parque Tecnológico de San Sebastián, 20009, San Sebastián/Donostia, Spain.
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14
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Cruz GN, Lima FS, Dias LG, El Seoud OA, Horinek D, Chaimovich H, Cuccovia IM. Molecular Dynamics Simulations of the Initial-State Predict Product Distributions of Dediazoniation of Aryldiazonium in Binary Solvents. J Org Chem 2015; 80:8637-42. [PMID: 26263052 DOI: 10.1021/acs.joc.5b01289] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The dediazoniation of aryldiazonium salts in mixed solvents proceeds by a borderline SN1 and SN2 pathway, and product distribution should be proportional to the composition of the solvation shell of the carbon attached to the -N2 group (ipso carbon). The rates of dediazoniation of 2,4,6-trimethylbenzenediazonium in water, methanol, ethanol, propanol, and acetonitrile were similar, but measured product distributions were noticeably dependent on the nature of the water/cosolvent mixture. Here we demonstrated that solvent distribution in the first solvation shell of the ipso carbon, calculated from classical molecular dynamics simulations, is equal to the measured product distribution. Furthermore, we showed that regardless of the charge distribution of the initial state, i.e., whether the positive charge is smeared over the molecule or localized on phenyl moiety, the solvent distribution around the reaction center is nearly the same.
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Affiliation(s)
| | | | | | | | - Dominik Horinek
- Institute für Physikalische und Theoretischen Chemie, University of Regensburg , 93053 Regensburg, Germany
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15
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García Martínez A, de la Moya Cerero S, Osío Barcina J, Moreno Jiménez F, Lora Maroto B. The Mechanism of Hydrolysis of Aryldiazonium Ions Revisited: Marcus Theory vs. Canonical Variational Transition State Theory. European J Org Chem 2013. [DOI: 10.1002/ejoc.201300834] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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16
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Samanta D, Cinar ME, Das K, Schmittel M. Nonstatistical Dynamic Effects in the Thermal C2–C6 Diels–Alder Cyclization of Enyne–Allenes. J Org Chem 2013; 78:1451-62. [DOI: 10.1021/jo302524a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Debabrata Samanta
- Department
of Chemistry and Biology, Universität Siegen, Adolf-Reichwein-Strasse, D-57068 Siegen, Germany
| | - Mehmet Emin Cinar
- Department
of Chemistry and Biology, Universität Siegen, Adolf-Reichwein-Strasse, D-57068 Siegen, Germany
| | - Kalpataru Das
- Department
of Chemistry and Biology, Universität Siegen, Adolf-Reichwein-Strasse, D-57068 Siegen, Germany
| | - Michael Schmittel
- Department
of Chemistry and Biology, Universität Siegen, Adolf-Reichwein-Strasse, D-57068 Siegen, Germany
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17
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Martínez AG, de la Moya Cerero S, Teso Vilar E, García Fraile A. Water-trapping of unstable carbocations taking place into the inverted region of the Marcus equation. First experimental and computational evidence. Tetrahedron 2012. [DOI: 10.1016/j.tet.2012.01.076] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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18
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Abstract
The mechanism of chemical reactions between electron donors and acceptors continuously changes with the power of the donors and the acceptors. The interaction between the HOMO (d) of the donors and the LUMO (a*) of the acceptors or delocalization of electrons is important for the reactions. The electron d-to-a* transferred configuration mixes to a significant extent. As the donors and/or the acceptors are strong, their excited configurations appreciably mixes together with the transferred configuration. The d-a and d*-a* orbital interactions are important in addition to the d-a* interaction. Reactions have features characteristic of the excited-state reactions although the donor-acceptor system is not really excited, but in the ground state. This process is termed pseudoexcitation. The a-d-a*-d* interaction is important. For much stronger donors and acceptors, the electron transferred configuration is stable and predominant. Covalent bonds do not form but instead ionic pairs, and electron transfer results. A mechanistic spectrum of chemical reactions is composed of the delocalization, pseudoexcitation, and electron transfer bands.
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Affiliation(s)
- Satoshi Inagaki
- Deapartment of Chemistry, Facuty of Engineering, Gifu University, Yanagido, Gifu, 501-1193, Japan,
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19
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Cantillo D, Avalos M, Babiano R, Cintas P, Jiménez JL, Light ME, Palacios JC. Unusual aryl migration in a mesomeric betaine in the solid and liquid state: mechanistic insights into the SNAr reaction. J Org Chem 2010; 75:4300-3. [PMID: 20481589 DOI: 10.1021/jo100350t] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An intramolecular S(N)Ar mechanism has been identified in the unexpected aryl migration observed in a mesomeric betaine. The process changes drastically the optical and spectroscopic properties and should be a valuable model for related heteroaromatic systems.
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Affiliation(s)
- David Cantillo
- Departamento de Química Orgánica e Inorgánica, QUOREX Research Group, Facultad de Ciencias-UEX, Avda. de Elvas s/n E-06071 Badajoz, Spain.
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20
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Molecular dynamics simulations and mechanism of organic reactions: non-TST behaviors. ADVANCES IN PHYSICAL ORGANIC CHEMISTRY 2010. [DOI: 10.1016/s0065-3160(08)44004-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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21
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Litovitz AE, Keresztes I, Carpenter BK. Evidence for nonstatistical dynamics in the Wolff rearrangement of a carbene. J Am Chem Soc 2008; 130:12085-94. [PMID: 18700757 PMCID: PMC3585475 DOI: 10.1021/ja803230a] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Indexed: 11/30/2022]
Abstract
Two (13)C-labeled isomers of the formal Diels-Alder adduct of acetylmethyloxirene to tetramethyl 1,2,4,5-benzenetetracarboxylate have been synthesized. Flash vacuum thermolysis of these adducts leads to various isotopic isomers of acetylmethylketene, the ratios of which have been determined by NMR. The surprising finding that the principal product comes from methylpyruvoyl carbene rather than its more stable isomer diacetylcarbene is explained by MPWB1K density functional calculations, which show that the reactant probably undergoes a unimolecular rearrangement to a norcaradiene derivative prior to its fragmentation. Coupled-cluster calculations on the methylpyruvoyl carbene show that it is capable of undergoing three unimolecular isomerizations. The fastest is 1,2-acetyl migration to give acetylmethylketene directly. The next is rearrangement via acetylmethyloxirene to diacetylcarbene and thence by Wolff rearrangement to acetylmethylketene. The least-favorable reaction is degenerate rearrangement via 1,3-dimethyl-2-oxabicyclo[1.1.0]butan-4-one (the epoxide of dimethylcyclopropenone). The combined experimental and computational results indicate that Wolff rearrangement of the diacetylcarbene occurs with a 2.5:1 ratio of the methyl groups despite the fact that they are related by a twofold axis of symmetry in the carbene. Preliminary molecular dynamics simulations are consistent with this conclusion. Taken together, the results suggest that the Wolff rearrangement is subject to the same kind of nonstatistical dynamical effects detected for other kinds of thermally generated reactive intermediates.
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Affiliation(s)
- Aviva E Litovitz
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
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22
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Dichiarante V, Salvaneschi A, Protti S, Dondi D, Fagnoni M, Albini A. The beta effect of silicon in phenyl cations. J Am Chem Soc 2007; 129:15919-26. [PMID: 18052166 DOI: 10.1021/ja074778x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Irradiation of chloroanisoles, phenols, and N,N-dimethylanilines bearing a trimethylsilyl (TMS) group in the ortho position with respect to the chlorine atom caused photoheterolysis of the Ar-Cl bond and formation of the corresponding ortho-trimethylsilylphenyl cations in the triplet state. The beta effect of silicon on these intermediates has been studied by comparing the resulting chemistry in alcoholic solvents with that of the silicon-free analogues and by computational analysis (at the UB3LYP/6-311+G(2d,p) level in MeOH). TMS groups little affect the photophysics and the photocleavage of the starting phenyl chlorides, while stabilizing the phenyl cations, both in the triplet (ca. 4 kcal/mol per group) and, dramatically, in the singlet state (9 kcal/mol). As a result, although triplet phenyl cations are the first formed species, intersystem crossing to the more stable singlets is favored with chloroanisoles and phenols. Indeed, with these compounds, solvent addition to give aryl ethers (from the singlet) competed efficiently with reduction or arylation (from the triplet). In the case of the silylated 4-chloro-N,N-dimethylaniline, the triplet cation remained in the ground state and trapping by pi nucleophiles remained efficient, though slowed by the steric bulk of the TMS group. In alcohols, the silyl group was eliminated via a photoinduced protiodesilylation during the irradiation. Thus, the silyl group could be considered as a directing, photoremovable group that allowed shifting to the singlet phenyl cation chemistry and was smoothly eliminated in the same one-pot procedure.
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Affiliation(s)
- Valentina Dichiarante
- Department of Organic Chemistry, University of Pavia, viale Taramelli 10, 27100 Pavia, Italy
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23
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Hubbard A, Okazaki T, Laali KK. Halo- and Azidodediazoniation of Arenediazonium Tetrafluoroborates with Trimethylsilyl Halides and Trimethylsilyl Azide and Sandmeyer-Type Bromodediazoniation with Cu(I)Br in [BMIM][PF6] Ionic Liquid. J Org Chem 2007; 73:316-9. [DOI: 10.1021/jo701937e] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Abigail Hubbard
- Department of Chemistry, Kent State University, Kent, Ohio 44242
| | - Takao Okazaki
- Department of Chemistry, Kent State University, Kent, Ohio 44242
| | - Kenneth K. Laali
- Department of Chemistry, Kent State University, Kent, Ohio 44242
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24
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Schmittel M, Vavilala C, Jaquet R. Elucidation of nonstatistical dynamic effects in the cyclization of enyne allenes by means of kinetic isotope effects. Angew Chem Int Ed Engl 2007; 46:6911-4. [PMID: 17680572 DOI: 10.1002/anie.200700709] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Michael Schmittel
- FB 8 (Chemie - Biologie), Universität Siegen, Adolf-Reichwein-Strasse 2, 57068 Siegen, Germany.
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25
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Slegt M, Overkleeft HS, Lodder G. Fingerprints of Singlet and Triplet Phenyl Cations. European J Org Chem 2007. [DOI: 10.1002/ejoc.200700339] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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26
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Schmittel M, Vavilala C, Jaquet R. Charakterisierung nichtstatistischer dynamischer Effekte in der Cyclisierung von Eninallenen mittels kinetischer Isotopeneffekte. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200700709] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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27
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Ussing BR, Hang C, Singleton DA. Dynamic effects on the periselectivity, rate, isotope effects, and mechanism of cycloadditions of ketenes with cyclopentadiene. J Am Chem Soc 2007; 128:7594-607. [PMID: 16756316 PMCID: PMC2453781 DOI: 10.1021/ja0606024] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The cycloadditions of cyclopentadiene with diphenylketene and dichloroketene are studied by a combination of kinetic and product studies, kinetic isotope effects, standard theoretical calculations, and trajectory calculations. In contrast to recent reports, the reaction of cyclopentadiene with diphenylketene affords both [4 + 2] and [2 + 2] cycloadducts directly. This is surprising, since there is only one low-energy transition structure for adduct formation in mPW1K calculations, but quasiclassical trajectories started from this single transition structure afford both [4 + 2] and [2 + 2] products. The dichloroketene reaction is finely balanced between [4 + 2] and [2 + 2] cycloaddition modes in mPW1K calculations, as the minimum-energy path (MEP) leads to different products depending on the basis set. The MEP is misleading in predicting a single product, as trajectory studies for the dichloroketene reaction predict that both [4 + 2] and [2 + 2] products should be formed. The periselectivity does not reflect transition state orbital interactions. The (13)C isotope effects for the dichloroketene reaction are well-predicted from the mPW1K/6-31+G** transition structure. However, the isotope effects for the diphenylketene reaction are not predictable from the cycloaddition transition structure and transition state theory. The isotope effects also appear inconsistent with kinetic observations, but the trajectory studies evince that nonstatistical recrossing can reconcile the apparently contradictory observations. B3LYP calculations predict a shallow intermediate on the energy surface, but trajectory studies suggest that the differing B3LYP and mPW1K surfaces do not result in qualitatively differing mechanisms. Overall, an understanding of the products, rates, selectivities, isotope effects, and mechanism in these reactions requires the explicit consideration of dynamic trajectories.
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Affiliation(s)
- Bryson R Ussing
- Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77842, USA
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28
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Chiang CT, Freindorf M, Furlani T, DeLeon RL, Richard JP, Garvey JF. Enhancement of a Lewis Acid−Base Interaction via Solvation: Ammonia Molecules and the Benzene Radical Cation. J Phys Chem A 2007; 111:6068-76. [PMID: 17569513 DOI: 10.1021/jp071349c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The interaction between ammonia and the benzene radical cation has been investigated by gas-phase studies of mass selected ion clusters {C(6)H(6)-(NH(3))(n=0-8)}(+) via tandem quadrupole mass spectrometry and through calculations. Experiments show a special stability for the cluster ion that contains four ammonias: {C(6)H(6)(NH(3))(4)}(+). Calculations provide evidence that the first ammonia forms a weak dative bond to the cyclohexadienyl radical cation, {C(6)H(6)-NH(3)}(+), where there is a transfer of electrons from ammonia to benzene. Additional solvating ammonia molecules form stabilizing hydrogen bonds to the ring-bound ammonia {C(6)H(6)-NH(3)}(+).(NH(3))(n), which cause cooperative changes in the structure of the cluster complex. Free ammonia is a weak hydrogen bond donor, but electron transfer from NH(3) to the benzene ring that strengthens the dative bond will increase the hydrogen acidity and the strength of the cluster hydrogen bonds to the added ammonia. A progressive "tightening" of this dative bond is observed upon addition of the first, second, and third ammonia to give a cluster stabilized by three N-(+)H x N hydrogen bonds. This shows that the energetic cost of tightening the dative bond is recovered with dividends in the formation of stable cluster hydrogen bonds.
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Affiliation(s)
- Chi-Tung Chiang
- Department of Chemistry, University at Buffalo, State University of New York at Buffalo, Buffalo, New York 14260-3000, USA
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29
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Tsuji Y, Richard JP. When does an intermediate become a transition state? Degenerate isomerization without competing racemization during solvolysis of (S)-1-(3-nitrophenyl)ethyl tosylate. J Am Chem Soc 2007; 128:17139-45. [PMID: 17177468 PMCID: PMC2546492 DOI: 10.1021/ja066235d] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
(S)-1-(3-Nitrophenyl)ethyl tosylate [(S)-2-OTs] was prepared in >99% enantiomeric excess and the change in the chiral purity of this compound was monitored during solvolysis in 50:50 trifluoroethanol/water. The barely detectable formation of 0.5% (R)-2-OTs after two half times for the solvolysis reaction was used to calculate a rate constant of k(rac) approximately equal to 4 x 10-6 s-1. This is 80-fold smaller than kiso = 3.2 x 10-4 s-1 for the isomerization that exchanges oxygen-16 and oxygen-18 of 3-NO2C6H413CH(Me)OS(18O)2Tos during solvolysis and 10-fold smaller than the minimum value of k(rac) = 4.6 x 10-5 s-1 predicted if isomerization and racemization products form by partitioning of a common ion-pair intermediate of a stepwise reaction. It is concluded that the isomerization reaction proceeds mainly by a pathway that avoids formation of this putative intermediate. It is suggested that the solvolysis reaction of 2-OTs may proceed by a stepwise preassociation mechanism where solvent "reorganization" precedes substrate ionization to form an ion-pair intermediate.
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Affiliation(s)
- Yutaka Tsuji
- Department of Biochemistry and Applied Chemistry, Kurume National College of Technology, Komorinomachi, Kurume 830-8555, Japan
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30
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Winkler M, Sander W. Generation and Reactivity of the Phenyl Cation in Cryogenic Argon Matrices: Monitoring the Reactions with Nitrogen and Carbon Monoxide Directly by IR Spectroscopy. J Org Chem 2006; 71:6357-67. [PMID: 16901116 DOI: 10.1021/jo0603678] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The phenyl cation 1 has been prepared by co-deposition of iodobenzene 6 or bromobenzene 7 with a microwave-induced argon plasma and characterized by IR spectroscopy in cryogenic argon matrices. The cation can clearly be identified by its strongest absorption at 3110 cm(-1) that is rapidly bleached upon visible light irradiation. This characteristic band is observed neither in the conventional photochemistry of 6 or 7 nor in discharge experiments with alkyl halides or chlorobenzene. The latter finding is in line with energetic considerations. According to density functional theory (DFT) computations, the strongest absorption of 1 is caused by a C-H stretching vibration that involves almost entirely the ortho-hydrogens. This is confirmed by isotopic labeling experiments. Co-deposition of halobenzene/N2 mixtures leads to a decrease of the 3110 cm(-1) absorption, whereas several new signals are detected in the 2200-2400 cm(-1) range of the IR spectrum. Annealing of a matrix that contains 1 and 1% N2 leads to an increase of a broad band at 2260 cm(-1) that is assigned to the benzenediazonium ion 2. A sharp signal at 2327 cm(-1) that had previously been assigned to the N-N stretching vibration of 2 is due to molecular nitrogen. The mechanism that triggers the IR activity of N2 is not yet understood. Annealing of a matrix that contains 1 and 0.5% CO leads to an increase of a broad band at 2217 cm(-1) that is considerably stronger than the 2260 cm(-1) absorption of 2. This signal is assigned to the C-O stretching vibration of the benzoyl cation 12, in excellent agreement with previous investigations of 12 in superacidic media. Some consequences of the measured frequencies with regard to bonding in 2 and 12 are discussed.
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Affiliation(s)
- Michael Winkler
- Lehrstuhl für Organische Chemie II der Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
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31
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Bini R, Chiappe C, Marmugi E, Pieraccini D. The “non-nucleophilic” anion [Tf2N]– competes with the nucleophilic Br–: an unexpected trapping in the dediazoniation reaction in ionic liquids. Chem Commun (Camb) 2006:897-9. [PMID: 16479304 DOI: 10.1039/b514988f] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Imidazolium ionic liquids containing [Tf2N]- anion are not as innocent as they are often considered; [Tf2N]- is more reactive than Br- in heterolytic dediazoniation reactions.
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Affiliation(s)
- Riccardo Bini
- Dipartimento di Chimica Bioorganica e Biofarmacia, via Bonanno 33, 56126, Pisa, Italy
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32
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Crich D, Hutton TK, Ranganathan K. Is There a Homolytic Substitution Chemistry (SH2) of Sulfones? J Org Chem 2005; 70:7672-8. [PMID: 16149798 DOI: 10.1021/jo050990c] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[reaction: see text] A series of 2-alkylsulfonyl-2'-biphenyl radicals, in which the alkyl group is primary, secondary, or tertiary, were generated and the products of their reactions investigated. Dibenzothiophene S,S-dioxide was not identified among the products, which arose mainly from intramolecular hydrogen abstraction from the alkyl group or addition to the solvent, benzene. On this basis, it is concluded that homolytic substitution at sulfonyl sulfur, if possible at all, is too slow to take precedence over a number of competing decomposition pathways. Previous literature results suggesting the possibility of intramolecular homolytic substitution at sulfonyl sulfur may be explained by alternative processes.
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Affiliation(s)
- David Crich
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607-7061, USA.
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