101
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Domingo LR, Arnó M, Contreras R, Pérez P. Density Functional Theory Study for the Cycloaddition of 1,3-Butadienes with Dimethyl Acetylenedicarboxylate. Polar Stepwise vs Concerted Mechanisms. J Phys Chem A 2002. [DOI: 10.1021/jp012603i] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Luis R. Domingo
- Instituto de Ciencia Molecular and Departamento de Química Orgánica, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain, Departamento de Química, Facultad de Ciencias, Universidad de Chile, Casilla 653-Santiago, Chile, and Departamento de Química Física, Facultad de Química, Pontificia Universidad Católica de Chile, Casilla 306, Correo 22, Santiago, Chile
| | - Manuel Arnó
- Instituto de Ciencia Molecular and Departamento de Química Orgánica, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain, Departamento de Química, Facultad de Ciencias, Universidad de Chile, Casilla 653-Santiago, Chile, and Departamento de Química Física, Facultad de Química, Pontificia Universidad Católica de Chile, Casilla 306, Correo 22, Santiago, Chile
| | - Renato Contreras
- Instituto de Ciencia Molecular and Departamento de Química Orgánica, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain, Departamento de Química, Facultad de Ciencias, Universidad de Chile, Casilla 653-Santiago, Chile, and Departamento de Química Física, Facultad de Química, Pontificia Universidad Católica de Chile, Casilla 306, Correo 22, Santiago, Chile
| | - Patricia Pérez
- Instituto de Ciencia Molecular and Departamento de Química Orgánica, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain, Departamento de Química, Facultad de Ciencias, Universidad de Chile, Casilla 653-Santiago, Chile, and Departamento de Química Física, Facultad de Química, Pontificia Universidad Católica de Chile, Casilla 306, Correo 22, Santiago, Chile
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102
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Domingo LR, Asensio A, Arroyo P. Density functional theory study of the Lewis acid-catalyzed Diels-Alder reaction of nitroalkenes with vinyl ethers using aluminum derivatives. J PHYS ORG CHEM 2002. [DOI: 10.1002/poc.529] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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103
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Yu ZX, Dang Q, Wu YD. Aromatic dienophiles. 1. A theoretical study of an inverse-electron demand Diels-Alder reaction between 2-aminopyrrole and 1,3,5-triazine. J Org Chem 2001; 66:6029-36. [PMID: 11529728 DOI: 10.1021/jo010243p] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study is devoted to a detailed theoretical study of an inverse-electron demand Diels-Alder reaction (IDA) with 1,3,5-triazine as the diene and 2-aminopyrrole 1A(alpha) as the dienophile, which is a key step in a cascade reaction for the one-pot synthesis of purine analogues. Geometries were optimized with the B3LYP/6-31G* method and energies were evaluated with the MP2/6-311++G** method. This IDA reaction occurs through a stepwise mechanism, where the first step corresponds to the nucleophilic attack of 2-aminopyrrole to triazine to form a zwitterionic intermediate, which is in equilibrium with a neutral intermediate through a hydrogen transfer process, followed by a rate-determining ring-closure step. It is shown that the B3LYP method significantly overestimates the activation energy, whereas the MP2 method offers a reasonable activation barrier of 27.9 kcal/mol in the gas phase. The solvation effect has been studied by the PCM model. In DMSO, the calculated activation energy of the IDA reaction is decreased to 24.0 kcal/mol with a strong endothermicity of 17.4 kcal/mol due to the energy penalty of transforming two aromatic reactants into a nonaromatic IDA adduct. The possible stepwise [2+2] pathway is ruled out based on its higher activation and reaction energies than those of the [4+2] pathway. By comparing the IDA reactions of triazine to 2-aminopyrrole and pyrrole, we address two crucial roles of the alpha-amino substituent in lowering activation and reaction energies and controlling the reaction regiochemistry.
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Affiliation(s)
- Z X Yu
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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104
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Domingo LR, Oliva M, Andrés J. A theoretical study of the reaction between cyclopentadiene and protonated imine derivatives: a shift from a concerted to a stepwise molecular mechanism. J Org Chem 2001; 66:6151-7. [PMID: 11529744 DOI: 10.1021/jo0015422] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reaction between cyclopentadiene and protonated pyridine-2-carboxaldehyde imine derivatives has been studied by using Hartree-Fock (HF) and B3LYP methods together with the 6-31G basis set. The molecular mechanism is stepwise along an inverted energy profile. This results from the protonation on both nitrogen atoms of the imine group and the pyridine framework. The first step corresponds to the nucleophilic attack of cyclopentadiene on the electron-poor carbon atom of the iminium cation group to give an acyclic cation intermediate, and the second step is associated with the ring closure of this intermediate via the formation of a C-N single bond yielding the final cycloadduct. Two reactive channels have been characterized corresponding to the endo and exo approach modes of the cyclopentadiene to the iminium cation. The role of the pyridium cation substituent and the nitrogen position (ortho, meta, and para) along the reaction pathway has been also considered. Solvent effects (dichloromethane) by means of a continuum model have been taken into account to model the experimental environment.
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Affiliation(s)
- L R Domingo
- Intituto de Ciencia Molecular, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain.
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105
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Domingo L, Oliva M, Andrés J. A PM3 study of the molecular mechanism for the cycloaddition between cyclopentadiene and protonated pyridine-imine derivatives. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s0166-1280(01)00370-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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106
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A theoretical study of the selectivity for the domino [5+2]/[4+2] cycloadditions of γ-pyrones bearing tethered alkenes with substituted 1,3-butadienes. Tetrahedron 2001. [DOI: 10.1016/s0040-4020(01)00464-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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107
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Domingo LR. A theoretical study of the molecular mechanism of the reaction between N,N-dimethylmethyleneammonium cation and cyclopentadiene. J Org Chem 2001; 66:3211-4. [PMID: 11325291 DOI: 10.1021/jo001332p] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- L R Domingo
- Instituto de Ciencia Molecular, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain.
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108
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Theoretical study on the mechanism of the domino reactions of tertiary α-cyano-enamines and dimethyl acetylenedicarboxylate. Tetrahedron 2001. [DOI: 10.1016/s0040-4020(00)00989-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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109
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Affiliation(s)
- A Kumar
- Physical Chemistry Division, National Chemical Laboratory, Pune 411 008, India.
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110
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Orozco M, Luque FJ. Theoretical Methods for the Description of the Solvent Effect in Biomolecular Systems. Chem Rev 2000; 100:4187-4226. [PMID: 11749344 DOI: 10.1021/cr990052a] [Citation(s) in RCA: 454] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Modesto Orozco
- Departament de Bioquímica i Biologia Molecular, Facultat de Química, Universitat de Barcelona, Martí i Franqués 1, E-08028 Barcelona, Spain, and Departament de Fisicoquímica, Facultat de Farmàcia, Universitat de Barcelona, Avgda. Diagonal s/n, E-08028 Barcelona, Spain
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111
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Abstract
The molecular mechanism for the intramolecular [5 + 2] cycloaddition reaction of beta-silyloxy-gamma-pyrones bearing tethered alkenes has been characterized using ab initio methods. A comparative study for this sort of cycloaddition carried out at different computational levels points out that the B3LYP/6-31G calculations give similar barriers to those obtained with the MP3/6-31G level. Analysis of the energetic results shows that the reaction takes place along a stepwise process: first, the migration of the neighboring silyl group to the carbonyl group of the gamma-pyrone takes place to give a weak oxidopyrylium ylide intermediate, which by a subsequent concerted intramolecular [5 + 2] cycloaddition affords the final cycloadduct. The cycloaddition process is very stereoselective due to the constraints imposed by the tether. The [5 + 2] cycloaddition reaction has a large barrier, and the presence of the silyloxy group and the intramolecular character of the process are necessary to ensure the thermodynamic and kinetic feasibility of these cycloadditions.
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112
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Mayr H, Ofial A, Sauer J, Schmied B. [2++4] Cycloadditions of Iminium Ions − Concerted or Stepwise Mechanism of Aza Diels−Alder Reactions? European J Org Chem 2000. [DOI: 10.1002/1099-0690(200006)2000:11<2013::aid-ejoc2013>3.0.co;2-a] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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113
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Domingo L. Theoretical Study of 1,3-Dipolar Cycloaddition Reactions with Inverse Electron Demand − A DFT Study of the Lewis Acid Catalyst and Solvent Effects in the Reaction of Nitrones with Vinyl Ethers. European J Org Chem 2000. [DOI: 10.1002/1099-0690(200006)2000:12<2265::aid-ejoc2265>3.0.co;2-c] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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114
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Abstract
The first synthesis of (+)-casuarine ((+)-6), a pentahydroxy pyrrolizidine alkaloid of the alexine/australine subclass, is described. The key step is a tandem [4 + 2]/[3 + 2] nitroalkene cycloaddition involving nitrobenzoate 13, chiral vinyl ether 16c, and vinyl silane 10, which establishes five of the six stereocenters present in this potent glycosidase inhibitor. The completion of the synthesis requires only four additional steps to deliver the final product in 20% overall yield.
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Affiliation(s)
- S E Denmark
- Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801, USA
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115
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Abstract
The molecular mechanism of the domino inter [4 + 2]/intra [3 + 2] cycloaddition reactions of nitroalkenes with enol ethers to give nitroso acetal adducts has been characterized using density functional theory methods with the B3LYP functional and the 6-31G basis set. The presence of Lewis acid catalyst and solvent effects has been taken into account to model the experimental environment. These domino processes comprise two consecutive cycloaddition reactions: the first one is an intermolecular [4 + 2] cycloaddition of the enol ether to the nitroalkene to give a nitronate intermediate, which then affords the final nitroso acetal adduct through an intramolecular [3 + 2] cycloaddition reaction. The intermolecular [4 + 2] cycloaddition can be considered as a nucleophilic attack of the enol ether to the conjugated position of the nitroalkene, with concomitant ring closure and without intervention of an intermediate. For this cycloaddition process, the presence of the Lewis acid favors the delocalization of the negative charge that is being transferred from the enol ether to the nitroalkene and decreases the activation energy of the first cycloaddition. The [4 + 2] cycloaddition presents a total regioselectivity, while the endo/exo stereoselectivity depends on the bulk of the Lewis acid used as catalyst. Thus, for small Lewis acid catalyst, modeled by BH(3), the addition presents an endo selectivity. The [3 + 2] cycloaddition reactions present an total exo selectivity, due to the constraints imposed by the tether. Inclusion of Lewis acid catalyst and solvent effects decrease clearly the barrier for the first [4 + 2] cycloaddition relative to the second [3 + 2] one. Calculations for the activation parameters along this domino reaction allow to validate the results obtained using the potential energy barriers.
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116
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Boruah RC, Ahmed S, Sharma U, Sandhu JS. A Convenient Preparation of N-Acyl-1-aza-1,3-diene from β-Formylenamide and Its Utility in Inverse Electron Demand Diels−Alder Reactions. J Org Chem 2000. [DOI: 10.1021/jo9912911] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Romesh C. Boruah
- Organic Chemistry Division, Regional Research Laboratory, Jorhat 785006, India
| | - Shahadat Ahmed
- Organic Chemistry Division, Regional Research Laboratory, Jorhat 785006, India
| | - Utpal Sharma
- Organic Chemistry Division, Regional Research Laboratory, Jorhat 785006, India
| | - Jagir S. Sandhu
- Organic Chemistry Division, Regional Research Laboratory, Jorhat 785006, India
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117
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Domingo LR, Picher MT, José Aurell M. A DFT Characterization of the Mechanism for the Cycloaddition Reaction between 2-Methylfuran and Acetylenedicarboxylic Acid. J Phys Chem A 1999. [DOI: 10.1021/jp992579x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Luis R. Domingo
- Departamento de Química Orgánica, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain
| | - M. Teresa Picher
- Departamento de Química Orgánica, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain
| | - M. José Aurell
- Departamento de Química Orgánica, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain
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