Selection Rules for Sigmatropic Reactions

Woodward, R. B.; Hoffmann, Roald

doi:10.1021/ja01089a050

Cited by 450 publications

(284 citation statements)

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“…(21)). Equation (16) indicates that the numerator of each term on the right side of Eq. (8b) consists of two parts, the Coulomb interaction part and the exchange interaction part.…”

Section: Combinedmentioning

confidence: 99%

“…A similar behavior of these particular MO's has also been pointed out in nonplanar saturated molecules.) In addition, the conspicuous property of HO and LU in determining the steric course of organic reactions has been discovered and has attracted much attention.3, 16) In this view, it may be of interest to discuss the energy of reacting systems by dividing it into various kinds of interactions. Such a treatment will be useful in helping us to understand what factor is really important in the chemical reaction.…”

mentioning

confidence: 99%

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An MO-theoretical Interpretation of the Nature of Chemical Reactions. I. Partitioning Analysis of the Interaction Energy

FukuiKenichi

FujimotoHiroshi

1968

Bulletin of the Chemical Society of Japan

167

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The molecular interaction energy, without considering the nuclear configuration change, is discussed by partitioning it into the Coulomb, exchange, delocalization, and polarization terms. A succinct approximate expression for each term is derived, and its magnitude is discussed.The expressions obtained as the second-order perturbation terms for the delocalization and the polarization energies are in accord with those of the well-established reactivity indices, the delocalizability , and the self-atom polarizability respectively. The chemical reactivity can thus be measured by the combined sum of these four terms.In usual ionic reactions the Coulomb and the delocalization terms are more important than the exchange and the polarization terms respectively.

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“…(21)). Equation (16) indicates that the numerator of each term on the right side of Eq. (8b) consists of two parts, the Coulomb interaction part and the exchange interaction part.…”

Section: Combinedmentioning

confidence: 99%

mentioning

confidence: 99%

An MO-theoretical Interpretation of the Nature of Chemical Reactions. I. Partitioning Analysis of the Interaction Energy

FukuiKenichi

FujimotoHiroshi

1968

Bulletin of the Chemical Society of Japan

167

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“…For this purpose we selected the Cope rearrangement 26 of several fluxional molecules shown in scheme 1: bullvalene (I) and barbaralane (II) as well as semibullvalene (III, X=H) and its derivatives: 3-methylsemibullvalene (III, X=Me,); 3-aminosemibullvalene (III, X=NH 2 ) and 2,6-diazasemibullvalene (IV), and followed their intramolecular rearrangements at elevated temperatures by ab initio molecular dynamics (AIMD) 27 . The conservation of orbital topology dictated by the Woodward-Hoffmann (WH) rules 28,29 implies that the rearrangements of these molecules proceed in a concerted fashion. The concertedness can be followed by properly selected CSM-s. We have calculated the temporal variations of suitable CSM variables along the AIMD trajectories.…”

Section: Introductionmentioning

confidence: 99%

Effect of Temperature and Substitution on Cope Rearrangement: A Symmetry Perspective

2013

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Many reactions feature symmetry variation along the reaction path on the potential energy surface. The interconversion of the point group symmetry of the stationary points can be characteristic of these processes. Increasing the temperature, however, leads to the loss of symmetry in its traditional yes-no language. We find that in such cases the instantaneous distance of the molecular structure from its symmetric counterpart is a suitable collective variable that can describe the reaction process. We show that this quantity, the continuous symmetry measure (CSM) has a positive linear relationship with temperature, implying that even highly symmetric molecules should be considered as asymmetric above 0K. Using ab initio molecular dynamics we simulate the temperature induced Cope rearrangements of several fluxional molecules and employ different CSM-s to follow the reaction progress. We use this methodology to demonstrate the validity of important concepts governing these reactions: Woodward-Hoffmann rules and TS aromaticity. Statistical analysis of the CSM distributions reveals that ligands connected to the carbon frame have profound effect on the reaction course. In particular our results show that lower temperatures tend to enhance the differences between the TS-stabilizing effect of the substituents.

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“…Fig. l), following the suggestion of Woodward The isoindene6 (3) could undergo a hydrogen and Hoffmann (17), would consist of an indenyl shift to form the products, (1) and (2). This shift radical and a methyl radical, hydrogen atom, or probably occurs in the ground state of (31, since phenyl radical.…”

Section: Mechanistic Aspectsmentioning

confidence: 89%

“…Such species intervene in several reactions (17) are applied to the indene system. A reactions including photochemical (19-211, thermodel for the transition state for migration (see mal , and elimination (24, 251 processes.…”

Section: Mechanistic Aspectsmentioning

confidence: 99%

Photochemical rearrangement and dimerization of 1,1-disubstituted indenes

McCullough¹

1968

Can. J. Chem.

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The pliotochemical behavior of 1,l-diphenylindene and 1,l-dimethylindene has been studied. The fornicr undergoes efficient rearrangement on direct irradiation or on acetophenone sensitization, forming 2,3-diphenylindene and 1 ,Zdiphenylindene. In contrast, 1,l-dimethylindene gave n o detectable products of methyl migration but formed dimeric cyclobutanes on scnsitized and direct photolysis. The structures of thc two dimers formed in the sensitized reaction were assigned from their nuclear magnetic resonance spectra. It was also demonstrated that hydrogen, like methyl, migrated inefficiently if at all in this system. This difference in migrato~y aptitudes is discussed in terms of orbital symmetry of the indene system.

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Selection Rules for Sigmatropic Reactions

Cited by 450 publications

References 0 publications

An MO-theoretical Interpretation of the Nature of Chemical Reactions. I. Partitioning Analysis of the Interaction Energy

An MO-theoretical Interpretation of the Nature of Chemical Reactions. I. Partitioning Analysis of the Interaction Energy

Effect of Temperature and Substitution on Cope Rearrangement: A Symmetry Perspective

Photochemical rearrangement and dimerization of 1,1-disubstituted indenes

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