The application of the Woodward–Hoffmann orbital symmetry rules to concerted organic reactions

Gill, G. B.

doi:10.1039/qr9682200338

Cited by 71 publications

(50 citation statements)

References 3 publications

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“…More detailed interpretation of alternate reaction paths (such as the rearrangements of bicyclobutane) was based on an assumed monotonic correspondence between this overlap and the ease of a reaction route. The correspondence seemed consistent with experimental results [ 3 ] , but the lack of a firm basis for the correspondence was a weak point in the scheme. The purpose of this report is to describe the formalism and a few applications of an energybased mapping analysis, which promises to provide a more detailed understanding of the energetics of concerted reactions.…”

Section: Introductionsupporting

confidence: 80%

“…The prediction of conrotatory thermal closure has been supported in elaborate experimental detail [3]. However, the systems treated experimentally only rarely had the symmetry which made possible the standard Woodward-Hoffmann analysis, and in some cases it was not clear that the perfectly planar cis-butadiene was ever achieved [12].…”

Section: A Rearrangement Of Butadienesmentioning

confidence: 99%

“…195 It is possible to place constraints on the angles associated with a transform which guarantee that F is positive. Recall that any 2 x 2 rotation is specified by a single angle, and that any unitary transform may be expressed as a product of a finite number of 2 x 2 rotations [3]. For simplicity, we consider a single factor in this product, specified by the angle g, affecting the orbitals p and q on atom A .…”

Section: Introductionmentioning

confidence: 99%

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Energy-based formalism for the mapping analysis of concerted reactions

Trindle

Collins

2009

Int. J. Quantum Chem.

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X multiconfigurational mapping formalism is developed, by which the states of a set of reaction products are described in terms of the configurations of the original reactant system. Each reactant configuration is mapped into a wave function of the products, and an optimum mix of the mapped functions is obtained by configuration interaction. T h e principle governing the mapping is that the topology of bonding and antibonding in the system cannot be altered, although the shapes of the bonding and antibonding regions can be distorted by bends, twists, and stretches.Results of the calculation allow predictions of allowed or forbidden nature of reactions similar to those of M'oodward and Hoffmann [l], but the new analysis is fully automated and independent of point group symmetry. Identification of the particular excited state(s) leading to certain products in thermally forbidden reactions is considerably simplified by this analysis. Calculations on relatively well-understood systems, the pyrolysis of cyclobutane and the closure of both a symmetric and chiral butadiene, illustrate this approach to the study of concerted reactions.

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Section: Introductionsupporting

confidence: 80%

Section: A Rearrangement Of Butadienesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Energy-based formalism for the mapping analysis of concerted reactions

Trindle

Collins

2009

Int. J. Quantum Chem.

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“…Such an addition is formally a 2n + 6n addition, which is excited state symmetry allowed (28b), but is a rare process (31). This addition results in a temporary loss of aromaticity in the intermediate, which can be regained in one ring by the electrocyclic reaction in which the cycloCan.…”

Section: Possible Routes To Structures 6 7 Andmentioning

confidence: 99%

Photo-additions of Naphthalene Derivatives with Substituted Ethylenes: Influence of Methoxy- and Cyano-substituents on the Products

Chamberlain¹,

McCullough²

1973

Can. J. Chem.

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Irradiation of 2-methoxynaphthalene and acrylonitrile in ethanol affords exo-and endo-7-cyano-6-methoxy-2,3-benzobicyclo[4.2.0]octa-2,4-diene, in the ratio 30:70. The structures are assigned from the n.m.r. spectra. The endo compound is the more stable, and on base equilibration predominates (90%). These adducts eliminate a methoxy-group on treatment with tert-butoxide at 80a, to afford 2,3-naphthocyclobutene carboxamide. Irradiation of 2-cyanonaphthalene and methyl vinyl ether in ethanol gives a complicated mixture of adducts which includes the cyclobutane 7-methoxy-6-cyano-2,3-benzobicyclo-[4.2.0]octa-2,4-diene as a major product (35%). Also formed are 7-methoxy-2,3(8-cyanobenzo)bicyclo-[3.3.0]octa-2,7-diene (873, 8-methoxy-l0-cyano-l,2-benzocycloocta-l,3,5-triene (la%), and a dimer of the latter (779, and 8-methylene-5-methoxy-2,3(10-cyanobenzo)bicyco[2.2.I]heptene (35%). The structures of the latter adducts are assigned from spectroscopic data, including nuclear Overhauser effects. Possible mechanisms for formation of the latter adducts, and a rule for prediction of regiospecificity in cyclobutane formation, are proposed.

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“…The first step in the isomerization of flurbiprofen is the excitation of flurbiprofen methyl ester in its initial form to the first excited singlet state S1 since the symmetry of [1,3]-hydrogen shift from C14 to O18 is forbidden. [23][24][25] As is evident from Fig. 4, the UV spectrum indicated that the first vertical S1 excitation (HOMO to LUMO) occurs at λ=243.91 nm, with oscillator strength f=0.5776 and one at λ= 234.45 nm, with oscillator strength f=0.2194.…”

Section: Fig 2 R/s-flurbiprofen Enantiomersmentioning

confidence: 71%

A theoretical investigation of the flurbiprofen methyl ester isomerization as the main step in the photopreparation of anti-inflammatory medicine (S)-flurbiprofen: A DFT study

Hadidi¹,

Norouzibazaz²,

Shiri³

2020

10.5267/j.ccl

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In order to investigate the isomerization and conversion mechanism of the advantageous and widely used nonsteroidal anti-inflammatory medicine flurbiprofen, the hybrid density functional theory was applied. According to the results, the rearrangement reaction of (R)flurbiprofen to its (S)-enantiomer happens in a [1,3]-hydrogen shifts with inversion of configuration at chiral center C14. From the calculated energies, it can be understood that the rate-limiting step in the flurbiprofen isomerization is the excitation of (R)-flurbiprofen methyl ester in its initial form to the first excited singlet state S1 at λ=243.91 nm. we studied this process by scanning the C14-H17 distance for the excited singlet to get more information about the process of isomerization occurring upon excitation. The results of calculations demonstrated that the isomerization process should pass through a ~71 kcal/mol barrier. The (S)-flurbiprofen methyl ester is more photostable than its related (R)-enantiomer. This issue can be attributed to the -1.50 kcal/mol of thermodynamic stability of the (S)-flurbiprofen methyl ester.

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The application of the Woodward–Hoffmann orbital symmetry rules to concerted organic reactions

Cited by 71 publications

References 3 publications

Energy-based formalism for the mapping analysis of concerted reactions

Energy-based formalism for the mapping analysis of concerted reactions

Photo-additions of Naphthalene Derivatives with Substituted Ethylenes: Influence of Methoxy- and Cyano-substituents on the Products

A theoretical investigation of the flurbiprofen methyl ester isomerization as the main step in the photopreparation of anti-inflammatory medicine (S)-flurbiprofen: A DFT study

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