Thermal valence isomerizations: stereochemistry of the 2,4,6-octatriene to 5,6-dimethyl-1,3-cyclohexadiene ring closure

Marvell, Elliot N.; Caple, G.; Schatz, B.

doi:10.1016/s0040-4039(00)89964-5

Cited by 79 publications

(33 citation statements)

References 5 publications

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“…Hexatrienes undergo disrotatory ring closure by thermal activation to afford cyclohexadienes in agreement with the Woodward-Hoffmann rule (delocalization band in Scheme 8) [41][42][43]. Photo-irradiation of hexatrienes is known to give bicylic products in a stereospecific [4p a +2p a ] manner (delocalization band in Scheme 8) [40] in contrast to this rule.…”

Section: Delocalization Bandmentioning

confidence: 57%

A Mechanistic Spectrum of Chemical Reactions

Inagaki

2009

Orbitals in Chemistry

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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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Section: Delocalization Bandmentioning

confidence: 57%

A Mechanistic Spectrum of Chemical Reactions

Inagaki

2009

Orbitals in Chemistry

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“…Scheme2.Thermal conversion of 2E,4Z,6-E-hexatrienetocis-5,6-dimethyl-1,3-cyclohexadienebyV ogel [50] and Marvell. [74] mann's thesis (Table 3, bottom). Compound 11 also happens to be the lowest energy isomer of 9, 11-13 (Table 3, bottom).…”

Section: Corey and Hortmann'scompounds:s Tructural Assignments From 1964 And Structural Analyses Using Modern Computational Chemistrymentioning

confidence: 99%

On the Structural Assignments Underlying R. B. Woodward's Most Personal Data That Led to the Woodward–Hoffmann Rules: Subramania Ranganathan's Key Role and Related Research by E. J. Corey and A. G. Hortmann

Tantillo

Seeman

2021

Chemistry A European J

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In the early 1960s, as part of R. B. Woodward's isoxazole route to vitaminB 12 ,S ubramania Ranganathan uncovered two coupled sets of stereospecific reactions, at hermal set and ap hotochemicals et. These four reactions illustrated the alternatingc onfigurations that were the majord ata points that prompted the solution of the no-mechanism problem. Though Ranganathan's reactions played am ajor role, according to Woodward,i nt he development of the Woodward-Hoffmann rules, they were published only as part of the documentation of al ectureg iven by Woodward in 1966. The authors of this paper have uncovered Subramania Ranganathan's 1964 postdoctoral report and have used modern quantum chemical theory to predict the 1 HNMR spectra for Ranganathan's key compounds, providing support for the structure assignments madeb yW oodward and Ranganathan. As imilar set of alternating, stereospecific reactions was observed by E. J. Corey and Alfred Hortmann in their 1963t otal synthesis of dihydrocostunolide. We also have applied the computational process used for Ranganathan'sc ompounds to Hortmann's compounds, now also includingt he calculationo fc oupling constants, and find computational support for Coreya nd Hortmann's structure assignments.

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“…Thermische [l, 7 a]-sigmatropische H-Verschiebungen, deren bekanntestes und am besten untersuchtes Beispiel wohl die thermische Aquilibrierung von Pracalciferol und Vitamin D, ist [2], sind in den letzten Jahren bei einigen offenkettigen [3] und alicyclischen Trienen [4] Beim Erhitzen auf 225" in 1-proz. Decanlosung lagert sich &,cis-1 in das Isomere cis,trans-1 um; ebenso ergibt cis,truns-1, auf 225" erhitzt, cis, cis-1.…”

Section: Thermisches Verhalten Von O-dipropenylbenzol Beispiel Einerunclassified

Thermisches Verhalten von o‐Dipropenylbenzol, Beispiel einer aromatischen [1,7]‐sigmatropischen H‐Verschiebung. Vorläufige Mitteilung

Heimgartner¹,

Hansen²,

Schmid³

1970

Helvetica Chimica Acta

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cis, cis‐, cis, trans‐ and trans, trans‐o‐Dipropenylbenzene (cis, cis‐, cis, trans‐ and trans, trans‐1) were prepared. At 225° cis, cis‐1 isomerises to give cis, trans‐1 and vice versa. The isomerisation follows 1. order kinetics. At equilibrium 89% cis, trans‐ and 11% cis, cis‐1 are present. It is shown by deuterium labelling that the isomerisation is due to aromatic [1, 7 a] sigmatropic H‐shifts. trans, trans‐1 rearranges at 225° to yield 2, 3‐dimethyl‐1, 2‐dihydronaphthalene (3). This can be visualized by disrotatory ring closure of trans, trans‐1 followed by an aromatic [1, 5 s] H‐shift. When cis, cis‐ or cis, trans‐1 are heated for 153 hrs at 225° a small amount (3%) of 1‐ethyl‐1,2‐dihydronaphthalene (5) is formed.

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Thermal valence isomerizations: stereochemistry of the 2,4,6-octatriene to 5,6-dimethyl-1,3-cyclohexadiene ring closure

Cited by 79 publications

References 5 publications

A Mechanistic Spectrum of Chemical Reactions

A Mechanistic Spectrum of Chemical Reactions

On the Structural Assignments Underlying R. B. Woodward's Most Personal Data That Led to the Woodward–Hoffmann Rules: Subramania Ranganathan's Key Role and Related Research by E. J. Corey and A. G. Hortmann

Thermisches Verhalten von o‐Dipropenylbenzol, Beispiel einer aromatischen [1,7]‐sigmatropischen H‐Verschiebung. Vorläufige Mitteilung

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