Density Functional Study of the Oxy-Cope Rearrangement

Baumann, H.; Chen, Peter

doi:10.1002/1522-2675(20010131)84:1<124::aid-hlca124>3.0.co;2-n

Cited by 19 publications

(17 citation statements)

References 27 publications

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“…55 While generally oxy-Cope rearrangements proceed via concerted mechanisms, 56 the pathway taken is substrate dependent and nonconcerted reactions have also been reported. 57 Experimental observation of the rearranged product suggests the cleavage reaction must be followed by a rapid recombination step of the two closely associated intermediates. 55 A small amount of these intermediates that may escape the solvent cage and dissipate into the solution could help account for the observed crossover.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Heterolytic cleavage prior to C–C bond formation has been observed for anionic amino-Cope reactions . While generally oxy-Cope rearrangements proceed via concerted mechanisms, the pathway taken is substrate dependent and nonconcerted reactions have also been reported . Experimental observation of the rearranged product suggests the cleavage reaction must be followed by a rapid recombination step of the two closely associated intermediates .…”

Section: Resultsmentioning

confidence: 99%

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Base-Mediated Cascade Rearrangements of Aryl-Substituted Diallyl Ethers

et al. 2015

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Two base-mediated cascade rearrangement reactions of diallyl ethers were developed leading to selective [2,3]-Wittig-oxy-Cope and isomerization-Claisen rearrangements. Both diaryl and arylsilyl-substituted 1,3-substituted propenyl substrates were examined, and each exhibits unique reactivity and different reaction pathways. Detailed mechanistic and computational analysis was conducted, which demonstrated that the role of the base and solvent was key to the reactivity and selectivity observed. Crossover experiments also suggest that these reactions proceed with a certain degree of dissociation, and the mechanistic pathway is highly complex with multiple competing routes.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Base-Mediated Cascade Rearrangements of Aryl-Substituted Diallyl Ethers

et al. 2015

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“…The mechanism of this reaction and that of several other oxoanions, their neutral counterparts and the parent 1,5-hexadiene has been studied at the B3LYP level of theory. 60 These calculations suggest that there is a correlation between activation energy and the difference in pK a of the alcohol between the reactant and transition structure. This finding is in agreement with previous discussions of the rate acceleration.…”

Section: Reactionsmentioning

confidence: 99%

13 Computational organic chemistry

Yates

2002

Annu. Rep. Prog. Chem., Sect. B: Org. Chem.

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Conformational analysis remains one of the bread-and-butter activities of the computational organic chemist. The papers reviewed in this section represent a cross-section of this activity.Aziridine-2-carbonitrile. The energies of the cis and trans forms of aziridine-2carbonitrile (2) have been determined at very high levels of theory by Tschumper. 5 This state-of-the-art study included very large basis sets and the use of the coupled cluster CCSD(T) and Brueckner doubles BD(TQ) methods. The latter method included a perturbative treatment of the triple as well as quadruple excitations, as shown. The focal point analysis technique was then used to extrapolate to the basis set limit and obtain results of thermochemical accuracy. The best estimate of ∆G 0 from this study shows that the trans form lies 3.5 kJ mol Ϫ1 higher in energy than the cis. This value is in good agreement with previous theoretical studies, but not with the experimental estimate of the lower bound of 11 kJ mol Ϫ1 . The transition structure connecting the two isomers was also calculated and gives rise to an estimated barrier of 77.15 kJ mol Ϫ1 above the cis isomer. These results have significance in two areas of experimental research: the study of nucleic acid structure, and the determination of rotational spectra in interstellar dust clouds.Fumaric and maleic acids. The (E ) and (Z ) forms of butenedioic acid (fumaric and maleic acid, respectively) have been the subject of a combined molecular orbital and matrix isolation study. 6 The authors used the popular MP2 and B3LYP methods to determine the lowest energy rotational conformers of each structure (see 3). In each case these were shown to be planar, with the maleic acid incorporating an intramolecular hydrogen bond to form a seven-membered ring. The OH ؒ ؒ ؒ O = C hydrogen-bonded conformer was considerably lower in energy than the OH ؒ ؒ ؒ OH hydrogen-bonded conformer. Infrared spectra of the matrix isolated species indicated that the most stable conformers of maleic and fumaric acids were indeed present in the argon matrix.

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“…Recently, the antibody AZ28 was generated 4,5 to the transition state analogue (TSA) of the oxy-Cope rearrangement [6][7][8][9] which is an unusual pericyclic reaction that is widely used in organic synthesis. This rearrangement could occur by two different diradical pathways 6,8 and is not catalyzed by any known enzyme.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulation Study of the Negative Correlation in Antibody AZ28-Catalyzed Oxy-Cope Rearrangement

2002

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The oxy-Cope rearrangement reaction in the antibody AZ28 is investigated using ab initio molecular orbital calculations and molecular mechanical molecular dynamics simulations. This antibody, AZ28, is known as one of the few systems where the mature catalytic antibody shows a negative correlation between the transition state analogue (TSA) binding affinity and the catalytic rate of the oxy-Cope rearrangement compared to the germ line catalytic antibody. The ab initio optimized structure shows that the transition state structure has a more planar configuration than the TSA. The favorable electrostatic interactions between AZ28 and the transition state analogue overcome the unfavorable van der Waals interactions; thus, AZ28 shows higher binding affinity for the TSA than the germ line. However, the AZ28 is not flexible enough to accept the relatively planar transition state structure. Because the lower flexibility causes poorer antibody-hapten interaction energies, the activation free energy of the oxy-Cope rearrangement becomes larger in the mature antibody than the germ line. We show that the differences in flexibility between the germ line and the mature form and the differences in structure between TSA and the transition state are the origin of the negative correlation in AZ28-catalyzed oxy-Cope rearrangement. The mutation of residue 34 of the light chain, 34(L), affects the binding free energies through the interresidue interaction because it is the closest to the hapten among the six mutatable residues. However, it does not affect the negative correlation.

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Density Functional Study of the Oxy-Cope Rearrangement

Cited by 19 publications

References 27 publications

Base-Mediated Cascade Rearrangements of Aryl-Substituted Diallyl Ethers

Base-Mediated Cascade Rearrangements of Aryl-Substituted Diallyl Ethers

13 Computational organic chemistry

Molecular Dynamics Simulation Study of the Negative Correlation in Antibody AZ28-Catalyzed Oxy-Cope Rearrangement

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