Novel Mode of Formation of <i>cis,trans</i>‐1,5‐Cyclooctadiene

Martin, Hans‐Dieter; Heiser, B.; Kunze, M

doi:10.1002/anie.197806961

Cited by 9 publications

(2 citation statements)

References 7 publications

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“…On the other hand, when 6 is photolyzed, or when tricyclooctane is thermolyzed, the decomposition pathway is required to proceed through a diradical, and the percent of cis , cis -cyclooctadiene is significantly lower. Our calculations predict that pericyclic 6 -TS(A) is close in energy to the diradical pathways and corroborate the conclusion that decomposition of 6 lies on the border between a pericyclic and diradical regime 3 Product Mixture from Thermolysis and Gas-Phase Photolysis of 6 and Cyclooctatriene 17 …”

Section: Resultssupporting

confidence: 79%

One-Bond, Two-Bond, and Three-Bond Mechanisms in Thermal Deazetizations of 2,3-Diazabicyclo[2.2.2]oct-2-enes, trans-Azomethane, and 2,3-Diazabicyclo[2.2.1]hept-2-ene

Khuong

Houk

2003

J. Am. Chem. Soc.

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The thermal deazetizations of a series of substituted 2,3-diazabicyclo[2.2.2]oct-2-enes and some simpler model systems have been studied using the UB3LYP/6-31G(d) and CASPT2 methods, with a variety of active spaces. A fused cyclopropane exerts unique control on the mechanism and rate of deazetization. When the Walsh sigma-orbitals are appropriately aligned in an exo orientation, a pericyclic three-bond cleavage occurs. For an endo-fused cyclopropane, sequential one-bond cleavages occur to take advantage of orbital overlap with the Walsh orbitals. In systems lacking strongly directing substituents, concerted two-bond cleavage pathways to form diradical intermediates have a small enthalpic advantage (DeltaH(0K)++) over sequential one-bond cleavage pathways. However, the one-bond mechanism has an entropic advantage over the two-bond; consequently, at 400-500 K where decomposition occurs, one-bond and two-bond diradical cleavages both occur simultaneously. The thermal decompositions of trans-azomethane and 2,3-diazabicyclo[2.2.1]hept-2-ene are also studied, and the results are compared to extensive computational studies in the literature. Comparisons of UB3LYP, CASSCF, and CASPT2 surfaces for these reactions are made.

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Section: Resultssupporting

confidence: 79%

One-Bond, Two-Bond, and Three-Bond Mechanisms in Thermal Deazetizations of 2,3-Diazabicyclo[2.2.2]oct-2-enes, trans-Azomethane, and 2,3-Diazabicyclo[2.2.1]hept-2-ene

Khuong

Houk

2003

J. Am. Chem. Soc.

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“…In the former case, besides some unreacted vinyl sulfide lg, also isolated was 2,3-epoxy- Pyrolysis at 200 °C and direct and sensitized photolysis of the title compound (3a) produced only cts-1,3divinylcyclobutane (6a) and tricyclo[4.1.1.02,5]octane (7a). The latter hydrocarbon was prepared by an independent synthesis, which involved photochemical ring closure of bicyclo[4.1.1]octa-2,4-diene (8) to tricyclo[4.1.1.02,5]oct-3-ene (9), followed by hydrogenation of 9. The ratio of 6a to 7a was 2.4:1 in the pyrolysis reaction, 3.3:1 in the direct photolysis, and >50:1 when the photolysis of 3a was photosensitized.…”

Section: Methodsmentioning

confidence: 99%

On the stereochemistry and mechanism of the ozonation of some six-membered ring vinyl sulfides

Barillier¹,

Vazeux²

1986

J. Org. Chem.

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[2.2.2.2]/[2.1.1.1]Pagodanes and [1.1.1.1]/[2.2.1.1]/[2.2.2.2]Isopagodanes: Syntheses, Structures, Reactivities − Benzo/Ene- and Benzo/Benzo-Photocycloadditions

et al. 2000

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The established route to the [1.1.1.1]/[2.2.1.1]pagodanes (1, 2) has been applied to the construction of the homologous [2.2.2.2] and [2.1.1.1] skeletons (3, 7). Application of this synthetic scheme to the iso[1.1.1.1]/iso[2.2.1.1]/iso[2.2.2.2] structures (4−6) failed though; the crucial [6+6]benzo/benzo photocycloaddition step in the face-to-face benzo/benzo intermediates (26a and b) − in contrast to the corresponding clean [6+2]benzo/ene-photocycloaddition (27a Ǟ 36) − did not take place. A bypass involving a stereoelectronically less demanding [2+2]ene/ene-photocycloaddition proved rewarding when double Birch reduction was achieved with the benzo/benzo substrates (26a and b), giving 28a and b. Domino-type [4+2]/[4+2] cycloadditions to the thermally rather labile "benzene-cyclodimers" [33a and b, E a (33a) = 23.9 ± 1.5 kcal mol −1 ] allowed the subsequent completion of the isopagodane skeletons in standard manner. The attempts to convert the highly strained, yet thermally highly persistent, (iso)pagodanes (3−7) into one of the derived (iso)pagodadienes [A(AЈ), B(BЈ)] − the calculated energies (MMP2) are also

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Novel Mode of Formation of cis,trans‐1,5‐Cyclooctadiene

Cited by 9 publications

References 7 publications

One-Bond, Two-Bond, and Three-Bond Mechanisms in Thermal Deazetizations of 2,3-Diazabicyclo[2.2.2]oct-2-enes, trans-Azomethane, and 2,3-Diazabicyclo[2.2.1]hept-2-ene

One-Bond, Two-Bond, and Three-Bond Mechanisms in Thermal Deazetizations of 2,3-Diazabicyclo[2.2.2]oct-2-enes, trans-Azomethane, and 2,3-Diazabicyclo[2.2.1]hept-2-ene

On the stereochemistry and mechanism of the ozonation of some six-membered ring vinyl sulfides

[2.2.2.2]/[2.1.1.1]Pagodanes and [1.1.1.1]/[2.2.1.1]/[2.2.2.2]Isopagodanes: Syntheses, Structures, Reactivities − Benzo/Ene- and Benzo/Benzo-Photocycloadditions

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