Convenient New Synthesis of [7]Circulene

Yamamoto, Kōji; Sonobe, Hiroyuki; Matsubara, Hiroshi; Sato, Masaaki; Okamoto, Susumu; Kitaura, Kazuo

doi:10.1002/anie.199600691

Cited by 64 publications

(23 citation statements)

References 19 publications

(4 reference statements)

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“…The inversion between two twisted saddle‐shaped structures involves pseudorotation through a transition state with a C s ‐symmetric saddle‐shaped geometry, which is highly similar to [7]circulene. The barrier calculated at the B3LYP/6‐31G** level of theory is 12.9 kcal mol −1 , which is very close to the experimental value of 12.2 kcal mol −1 . Hence, the saddle‐to‐saddle inversion of [7]circulene should proceed through pseudorotation.…”

Section: Resultssupporting

confidence: 75%

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Per‐Substituted [8]Circulene and Its Non‐Planar Fragments: Synthesis, Structural Analysis, and Properties

Feng

Hsu

et al. 2016

Chemistry A European J

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The syntheses, structures, and physical properties of a full series of benzannulated tetraphenylenes are reported. The palladium-catalyzed annulation of tetraiodo-substituted 2,3,6,7,10,11,14,15-octamethyltetraphenylene with insufficient di(4-anisyl)ethyne yielded a mixture of per-substituted [8]circulene and its non-planar fragments, including mono-, para-di-, ortho-di-, and triannulated products. Their structures were unambiguously verified by X-ray crystallography. Successive benzannulations significantly affect the molecular geometries, dynamic behaviors, and physical properties of the compounds. In this series of compounds, [8]circulene is the most strained one, as reflected by the significant deplanarization of the phenanthrene moieties (ca. 63° in the bay region) and the fact that it has the highest strain energy (120.6 kcal mol(-1) ). The dynamic behaviors of these compounds were examined both experimentally and theoretically. The ring flipping of per-substituted [8]circulene is confirmed to proceed through pseudorotation with a barrier of around 21 kcal mol(-1) , whereas its non-planar fragments require much more energy for the ring inversion. The photophysical and electrochemical properties of the investigated compounds depend strongly on the extent of efficient π conjugation. The successive benzannulations red-shift both the absorption and the emission bands, and reduce the first oxidation potential.

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Section: Resultssupporting

confidence: 75%

“…Therefore, pseudorotation is the energetically favorable route. However, the barrier to the ring inversion of 1,2‐dihydro[7]circulene ( 9 ) has been determined to be 12.2 kcal mol −1 . If the inversion of [7]circulene proceeds through a planar transition state, then its barrier should be smaller than that of the inversion of compound 9 .…”

Section: Resultsmentioning

confidence: 99%

Per‐Substituted [8]Circulene and Its Non‐Planar Fragments: Synthesis, Structural Analysis, and Properties

Feng

Hsu

et al. 2016

Chemistry A European J

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“…14 In 1996, a different synthetic method was described. 15 Here the formation of both the central ring and the peripheral ring was accomplished in a single step using flash vacuum pyrolysis. Finally, the saturated positions were dehydrogenated using palladiumon-carbon to give the fully unsaturated [7]circulene (Scheme 4b).…”

Section: [6]circulenementioning

confidence: 99%

Synthesis of Heterocyclic [8]Circulenes and Related Structures

Hensel

Andersen

Plesner

et al. 2015

Synlett

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In this account we give an overview of the synthesis and properties of heterocyclic [8]circulenes. Much of the interest in studying heterocyclic [8]circulenes stems from the planar cyclooctatetraene core often contained in these compounds, which in principle is antiaromatic. We start with a short introduction to the hydrocarbon [n]circulenes and proceed to describe the synthetic chemistry involved in creating tetraoxa[8]circulenes, with particular focus on the acid-mediated oligomerization of benzo-or naphthoquinones, resulting in some simple rules for predicting the outcome of the oligomerization reactions. These rules have guided the synthetic strategies for the preparation of azatrioxa[8]circulenes and diazadioxa[8]circulenes, which will be described in separate sections of this account. More traditional synthetic strategies have been applied in the preparation of octathia[8]circulene, tetrathiatetraselena[8]circulene, and a number of other heterocyclic [8]circulenes, and these synthetic efforts will be highlighted. Finally, a section describing structures that are closely related to the heterocyclic [8]circulenes will be presented, and at the end we will comment on the extensive theoretical work regarding the question of aromaticity/antiaromaticity of the central cyclooctatetraene of heterocyclic[8]circulenes. 1 Introduction 2 Synthesis of [n]circulenes 2.1 [4]Circulene 2.2 [5]Circulene 2.3 [6]Circulene 2.4 [7]Circulene 2.5 [8]Circulene 3 Synthesis of Tetraoxa[8]circulenes: A Historical Perspective 4 Synthesis of Azatrioxa[8]circulenes 5 Synthesis of Diazadioxa[8]circulenes 6 Synthesis of Other Heterocyclic [8]Circulenes 7 Synthesis of Structurally Related Compounds 8 Hetero[8]circulenes and Related Compounds as Tools to Study Aromaticity and Antiaromaticity 9 Conclusion and Outlook

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“…Obviously, entrapment of a pentagon or a heptagon by hexagons-but not both contiguously-is a necessary condition for the growth of curved sp 2 structures, as illustrated in Figure 1.8 for the simplest case of [5]circulene (corannulene) and [7]circulene [58][59][60]; the presence of pentagon-heptagon pairs, as in a Stone-Wales defect (see Section 1.4.3), retains planarity [ Figure 1.8(c)]. So, as mentioned earlier, the interesting question is whether there is a counterbalancing efficient mechanism of pentagon elimination at flat graphene edges.…”

Section: 2 Heats Of Reaction Calculated For a Prototypical Process Omentioning

confidence: 99%

Physicochemical Properties of Carbon Materials: A Brief Overview

Radović

2008

Carbon Materials for Catalysis

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Convenient New Synthesis of [7]Circulene

Cited by 64 publications

References 19 publications

Per‐Substituted [8]Circulene and Its Non‐Planar Fragments: Synthesis, Structural Analysis, and Properties

Per‐Substituted [8]Circulene and Its Non‐Planar Fragments: Synthesis, Structural Analysis, and Properties

Synthesis of Heterocyclic [8]Circulenes and Related Structures

Physicochemical Properties of Carbon Materials: A Brief Overview

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