Activated Phenacenes from Phenylenes by Nickel‐Catalyzed Alkyne Cycloadditions

Gu, Zhenhua; Boursalian, Gregory B.; Gandon, Vincent; Padilla, Robin; Shen, H. F.; Timofeeva, Tatiana V.; Tongwa, Paul; Vollhardt, K. Peter C.; Yakovenko, Andrey A.

doi:10.1002/ange.201103428

Cited by 9 publications

(5 citation statements)

References 34 publications

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“…The twist angles θ 1 of the rings C and D were found to be 25.6 and 13.4°, respectively, whereas ring E is nearly planar—which is consistent with the results of the HOMA analysis that the rings C and D/E have weak and high aromaticity, respectively. The extent of distortion of the phenanthrene framework in compound 3 ( θ 2 =35.7°) is very close to those in 4,5‐dimethylphenanthrene (33.0°) and 5,6,7,8‐tetraphenyl[5]phenacene (31.1°) …”

Section: Resultsmentioning

confidence: 52%

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: Resultsmentioning

confidence: 52%

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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“…Although six four-membered rings are present in BC5, the MESP-based method suggests that the molecule may be stable and can be synthesized due to the dominance of aromatic character. In fact, the synthesis of BC5 is known in the literature, Vollhardt et al had reported the total synthesis of the first helical phenylenes (heliphenes), angular [6]-and [7]-phenylene, using a double cobalt-catalyzed cyclotrimerization strategy and a route for the preparation of such heliphene-based metal complexes. 6,68,69 The cyclic structure for three naphthalene−three cyclobutadiene-fused system NC32 is shown in Figure 8.…”

Section: ■ Methodologymentioning

confidence: 99%

“…Such a property provides useful hints for the design and synthesis of novel molecular frameworks . Many fused systems have been synthesized by connecting benzenoid hydrocarbons with antiaromatic cyclobutadiene, − pentalene, − indacene, − and so forth. These systems have been successfully applied for the design of various organo-electronic devices. − Cyclobutadiene, one of the classic antiaromatic organic molecules, has been used in the fused systems for modulating properties such as molecular conductivity, crystallization, segregation, thin-film formation, and so forth. − The fused systems are also found to be appropriate for the development of semiconductor materials.…”

Section: Introductionmentioning

confidence: 99%

Antiaromaticity–Aromaticity Interplay in Fused Benzenoid Systems Using Molecular Electrostatic Potential Topology

2021

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The phenomenon of antiaromaticity–aromaticity interplay in aromatic–antiaromatic (A–aA)-fused systems is studied using molecular electrostatic potential (MESP) analysis, which clearly brings out the electron-rich π-regions of molecular systems. Benzene, naphthalene, phenanthrene, and pyrene are the aromatic units and cyclobutadiene and pentalene are the antiaromatic units considered to construct the A–aA-fused systems. The fused system is seen to reduce the antiaromaticity by adopting a configuration containing the least number of localized bonds over antiaromatic moieties. This is clearly observed in 25 isomers of a fused system composed of three naphthalene and two cyclobutadiene units. Denoting the number of π-bonds in the cyclobutadiene rings by the notation (n, n′), the systems belonging to the class (0, 0) and (2, 2) turn out to be the most and least stable configurations, respectively. The stability of the fused system depends on the empty π-character of the antiaromatic ring, hence naphthalene and benzene prefer to fuse with cyclobutadiene in a linear and angular fashion, respectively. Generally, a configuration with the maximum number of ‘empty’ rings (0, 0, 0, ...) is considered to be the most stable for the given A–aA system. The stability and aromatic/antiaromatic character of A–aA-fused systems with pentalene is also interpreted in a similar way. MESP topology, clearly bringing out the distribution of double bonds in the fused systems, leads to a simple interpretation of the aromatic/antiaromatic character of them. Also, it leads to powerful predictions on stable macrocyclic A–aA systems.

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“…In addition to biphenylene itself, [ n ]phenylene has also been used as a substrate in transition metal‐catalyzed C–C bond activation. In 2011, Vollhardt and co‐workers reported Ni‐catalyzed [4+2] cycloaddition with alkyne to form phenacenes (Scheme ) . The C–C activation of angular [3]phenylene 36 proceeded with high regioselectivity for bay region, and both 38 and 39 were obtained.…”

Section: Reactions Of the Biphenylene Motifmentioning

confidence: 99%

Recent Advances of Biphenylene: Synthesis, Reactions and Uses

et al. 2019

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Biphenylene is an antiaromatic compound that has a strained butadiene skeleton that joins two benzene rings. Various methods for synthesizing the biphenylene core have been developed. In addition, the reactivity of biphenylene has attracted much attention because C–C bonds of biphenylene can be cleaved by various organometallic species. Furthermore, the biphenylene motif not only acts as a spacer in a variety of functional molecules, but also serves as a backbone for catalysts and ligands. This minireview summarizes how to construct the biphenylene structure, how to react biphenylene, and how to use the biphenylene skeleton in functional materials.

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Activated Phenacenes from Phenylenes by Nickel‐Catalyzed Alkyne Cycloadditions

Cited by 9 publications

References 34 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

Antiaromaticity–Aromaticity Interplay in Fused Benzenoid Systems Using Molecular Electrostatic Potential Topology

Recent Advances of Biphenylene: Synthesis, Reactions and Uses

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