Tetradehydrodinaphtho[10]annulene and its transformation into zethrene: A hitherto unknown dehydroannulene and a forgotten aromatic hydrocarbon

Umeda, Rui; Hibi, Daijiro; Miki, Koji; Tobe, Yoshito

doi:10.1351/pac-con-09-10-12

Cited by 39 publications

(47 citation statements)

References 45 publications

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“…The validity of this structure–property relationship has been computationally confirmed using various open‐shell singlet models and real compounds including hydrogen atom chains,6, 14, 18 p ‐quinodimethane model,14 diphenalenyl diradicaloids,19, 20 graphene nanoflakes,21–23 and transition metal compounds 24, 25. These results have been also supported by recent experimental data on two‐photon absorption26 and third harmonic generation,27 and they have stimulated other investigations on linear and NLO properties28–39 of multiradical compounds as well as their vibrational signatures 40, 41. In previous studies,20, 42, 43 spin‐unrestricted hybrid density functional theory (UDFT) calculations have shown that supermolecular and supramolecular multiradical systems composed of phenalenyl units are promising NLO systems, because their properties can be controlled by adjusting the architectures, the diradical characters, and the charge states.…”

Section: Introductionsupporting

confidence: 64%

Disease activity–guided rituximab therapy in rheumatoid arthritis: The effects of re‐treatment in initial nonresponders versus initial responders

Thurlings

Vos

Gerlag

et al. 2008

Arthritis & Rheumatism

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Objective. To explore the efficacy of re-treatment with rituximab in patients with rheumatoid arthritis (RA) who were initial nonresponders to treatment, and to evaluate the effects of rituximab in RA when retreatment is given in a standardized way based on the Disease Activity Score in 28 joints (DAS28), according to the international consensus statement.Methods. Patients with RA who had a DAS28 of >3.2 received up to 3 courses of rituximab at intervals of at least 6 months, regardless of whether the patient had responded to the first course of treatment with rituximab.Results. Of the 30 patients with RA who were included in the study, 26 could be evaluated for the efficacy of treatment after 6 months. Eighteen patients qualified for re-treatment at 6 months, 6 patients were re-treated at a later time point because of a disease relapse, and 2 other patients were not re-treated because they had low disease activity. Seven of the 24 patients who qualified for re-treatment had not exhibited clinical improvement after the first treatment course. These patients typically did not respond to subsequent courses of rituximab. Of interest, in the 17 patients who had exhibited a clinical response to the first course of rituximab, the second and third treatment courses resulted in European League Against Rheumatism responses similar to those observed after the first course, and no major relapses occurred before re-treatment.Conclusion. Rituximab re-treatment is not effective in patients who do not exhibit clinical improvement after the first treatment course, which is consistent with the notion that such patients represent a different pathogenetic subset of RA. Patients who initially responded to rituximab treatment experienced sustained benefit from DAS28-based systematic re-treatment according to the international consensus statement.

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Section: Introductionsupporting

confidence: 64%

Disease activity–guided rituximab therapy in rheumatoid arthritis: The effects of re‐treatment in initial nonresponders versus initial responders

Thurlings

Vos

Gerlag

et al. 2008

Arthritis & Rheumatism

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“…Dibenzo[de,mn]naphthacene (zethrene, 1 a, R= H) is a member of the benzenoid hydrocarbon family, [1] and has an interesting structure with respect to the formal definitions of aromaticity. The central two six-membered rings in zethrene (1 a) cannot present aromaticity associated with the KekulØ structure.…”

mentioning

confidence: 99%

Synthesis, Structure, and Photophysical Properties of Dibenzo[de,mn]naphthacenes

Chen

Hibi

et al. 2010

Angew Chem Int Ed

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“…Based on formal definitions of aromaticity, dibenzo‐[ de , mn ]naphthacene (zethrene, 21 ) has an interesting structure . The central two six‐membered rings in 21 cannot account for the aromaticity associated with its Kekulé structure.…”

Section: Zethrenes and Pyrroloarenesmentioning

confidence: 99%

“…The central two six‐membered rings in 21 cannot account for the aromaticity associated with its Kekulé structure. Zethrene and its derivatives were predicted to exhibit novel physical properties, which may have potential applications in electroluminescent devices and organic transistors …”

Section: Zethrenes and Pyrroloarenesmentioning

confidence: 99%

Metal‐Catalyzed Cascade Reactions: Useful Synthetic Tools for the Preparation of Polycyclic Arenes

Feng

Hsieh

2014

The Chemical Record

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This account summarizes our recent efforts to synthesize numerous important and interesting polycyclic arenes under mild conditions using metal-catalyzed protocols. The palladium-catalyzed annulations of 2-iodobiphenyls or 2,2'-diiodobiphenyls with alkynes efficiently generated phenanthrene derivatives. This synthetic method was utilized as the key step when preparing phenanthrene-based alkaloids, tetrabenzopyracylenes and persubstituted [8]circulenes. Depending on whether a palladium or nickel catalytic system was used, 1-ethynyl-8-iodonaphthalenes underwent either a cyclodimerization or a nitrile-incorporated cascade reaction to produce zethrenes or pyrroloarenes, respectively. Methylene-bridged polyarenes are generated easily from 2-halo-2'-methylbiaryls through benzylic C-H bond activation and subsequent carbon-carbon bond formation, and palladium complexes promote the arylation of methylene carbons. The palladium-catalyzed annulations of 1,8-bis(arylethynyl)naphthalene derivatives with o-diiodoarenes yielded benzo[k]fluoranthene-based linear acenes, which can be applied to synthesize highly curved fragments of fullerenes. The self-reactions of diarylethynes formed either dihydrocyclopenta[a]indenes or octaaryl-1,3,5,7-octatetraenes through palladium-catalyzed cycloisomerization or nickel-catalyzed tetramerization, respectively. In the presence of palladium catalysts, the hydroalkynylation of terminal arylalkynes directly generated angular trimerization adduct dienynes.

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Tetradehydrodinaphtho[10]annulene and its transformation into zethrene: A hitherto unknown dehydroannulene and a forgotten aromatic hydrocarbon

Cited by 39 publications

References 45 publications

Disease activity–guided rituximab therapy in rheumatoid arthritis: The effects of re‐treatment in initial nonresponders versus initial responders

Disease activity–guided rituximab therapy in rheumatoid arthritis: The effects of re‐treatment in initial nonresponders versus initial responders

Synthesis, Structure, and Photophysical Properties of Dibenzo[de,mn]naphthacenes

Metal‐Catalyzed Cascade Reactions: Useful Synthetic Tools for the Preparation of Polycyclic Arenes

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