- Contraction of π-Conjugated Rings upon Oxidation from Cyclooctatetraene to Benzene via the Tropylium Cation
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We have serendipitously discovered a unique transformation of a cyclooctatetraene derivative 1 into a cycloheptatriene spirolactone 3 upon oxidation, which is the first such transformation reported in 60 years. Product 3 could be reversibly interconverted into the aromatic tropylium cation 3H+ by acid/base treatment, which was accompanied by drastic spectroscopic changes. The resultant cycloheptatriene could be further converted into benzene upon oxidation. We characterized all the key structures by X-ray studies. Eventually, the π-conjugated ring size shrinks from 8 to 7, then finally to 6 upon oxidation, in the direction of the stronger aromatization.
- Tamoto, Akira,Aratani, Naoki,Yamada, Hiroko
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- Tridecacyclene: A Cyclic Tetramer of Acenaphthylene
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In this manuscript, we describe the single-step preparation of a cyclic tetramer of acenaphthylene through a Lewis acid-catalyzed aldol cyclization of 1-acenaphthenone. The previously unexplored cyclic tetramer material differs from the better-known cyclic trimer, decacyclene, due to the presence of a central eight-membered ring. This ring not only forces the molecule to distort significantly from planarity, but is also responsible for its unique electronic properties, including a decrease in the reduction potential (by about 0.4 eV) and optical gap (by about 0.73 eV), compared to the more planar decacyclene. The synthesized compound crystallizes into a unique packing structure with significant π-stacking observed between adjacent molecules. Furthermore, due to its saddle-like shape, the cyclic tetramer is able to form shape-complementary interactions between its concave surface and the convex outer surface of buckminsterfullerene to generate cocrystalline supramolecular assemblies. What a catch! A cyclic tetramer of acenaphthylene was synthesized in a single step. The compound exhibits interesting electronic and structural properties when compared to the better-known cyclic trimer due to the presence of a central eight-membered ring. The saddle-like shape of cyclic tetramer allows it to form cocrystalline supramolecular assemblies with C60 in the solid state (see scheme).
- Sumy, Daniel P.,Dodge, Nicholas J.,Harrison, Chloe M.,Finke, Aaron D.,Whalley, Adam C.
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- Trisannulated benzene derivatives by acid catalyzed aldol cyclotrimerizations of cyclic ketones. methodology development and mechanistic insight
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(Chemical Equation Presented) Several factors that contribute to the success of aldol cyclotrimerizations have been clarified as part of an effort to shed light on the inner workings of this century old reaction. The use of 4,7-di-tert-butylacenaphthenone (11) as a mechanistic probe molecule has led to intriguing discoveries about temperature, solvent, and solubility effects. Solvents that are both polarizable and somewhat polar, e.g., o-dichlorobenzene (ODCB), work best for the aromatic ketones examined. Certain Bronsted acids were found to work better than Lewis acids as catalysts for the archetypal aldol cyclotrimerization of indanone (2) in aprotic solvents, and a strong dependence on the pKa of the acid was observed. A standardized protocol, using p-toluenesulfonic acid monohydrate, is shown to work well in a number of test cases.
- Amick, Aaron W.,Scott, Lawrence T.
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- Study of structural aspects of thermochemical conversions of compounds modeling oligophenylenes containing acenaphthylenyl and acenaphthenyl groups
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With the aim of elucidating the mechanism of the thermochemical conversion of oligophenylenes containing acenaphthylenyl groups, the thermolysis of model compounds: 1,3,5-tris(5-acenaphthylenyl)benzene (1), 1,3,5-tris(5-acenaphthenyl)benzene (2), acenaphthylene, and acenaphthene, was studied by differential thermal analysis (DTA), dynamic thermogravimetric analysis (TGA), and mass spectrometry.Compounds 1 and 2 were studied by X-ray structural analysis.A scheme for the formation of secondary structures was suggested.Optimum temperature conditions were found for preparing thermostable, heat-resistant, and stable to thermooxidation polymers based on compounds containing the acenaphthylenyl groups. - Key words: 1,3,5-tris(acenaphthylenyl)benzene, 1,3,5-tris(acenaphthenyl)benzene, acenaphthylene, acenaphthene, thermochemical conversions; decacyclene; polymers, thermal properties; X-ray structural analysis.
- Kovalev, A. I.,Balykova, T. N.,Lindeman, S. V.,Teplyakov, M. M.,Khotina, I. A.,et al.
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- Palladium-catalyzed trimerization of strained cycloalkynes: Synthesis of decacyclene
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Palladium-catalyzed cyclotrimerization was applied to three strained cycloalkynes. Pd(PPh3)4 and Pt(PPh3)4-catalyzed cyclotrimerizations of cyclohexyne (2) afforded dodecahydrotriphenylene (3) in 64% and 62% yields, respectively, but subjecting cyclopentyne to the same conditions failed to afford isolable amounts of the cyclotrimer. Finally, decacyclene (15), a putative C60-fullerene precursor, was obtained in 23% yield by Pd2(dba)3-catalyzed cyclotrimerization of acenaphthyne (14).
- Iglesias, Beatriz,Pe?a, Diego,Pérez, Dolores,Guitián, Enrique,Castedo, Luis
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p. 486 - 488
(2007/10/03)
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- Novel Syntheses of Decacyclene by Deoxygenating Cyclotrimerisation of Acenaphthenequinone with Zero-valent Titanium or Phosphorus Pentasulfide
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Decacyclene (2) was obtained in 15-21% yield by reaction of acenaphthenequinone (6) with bis(η6-biphenyl)titanium(0) (9) in toluene or diglyme at 110°C and in 18% yield by reaction of 6 with phosphorus pentasulfide in boiling toluene. The new reactions are used to attempt the conversion of 3,8-dibromoacenaphthenequinone (7) to 3,4,9,10,15,16-hexabromodecacyclene (3) which is considered to serve as a suitable precursor for the bowl-shaped polycyclic aromatic hydrocarbon C 36H12 (1).
- Zimmermann, Klaus,Haenel, Matthias W.
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p. 609 - 611
(2007/10/03)
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- Utilisations synthetiques d'une electrode soluble au soufre. IV. Creation de l'enchainement C-S-C a partir d'hydrocarbures aromatiques, d'heterocycles et d'amines aromatiques
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Use of a sacrificial sulfur electrode in electroorganic chemistry.IV.Formation of the C-S-C bond from aromatic hydrocarbons, heterocycles and aromatic amines.The electrophile S2+ was prepared in organic media by oxidation of a carbon-sulfur electrode.This species can react with aromatic hydrocarbons, heterocycles and aromatic amines to produce organic monosulfides. carbon-sulfur electrode / sacrificial electrode / sulfur cation / organic sulfide / electrophilic substitution
- Do, Quang Tho,Elothmani, Driss,Simonet, Jacques,Guillanton, Georges Le
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p. 789 - 793
(2007/10/02)
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- Ramberg-Baecklund Reaction of 1,3-Dibromo-1H,3H-naphthothiopyran 2,2-Dioxide. Formation of Acenaphthyne Intermediate
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Radical bromination of 1H,3H-naphthothiopyran 2,2-dioxide (15) gave the corresponding monobromo sulfone 16 (48percent), dibromo sulfone 12 (43percent; cis/trans = 64/36), and tribromo sulfone 17 (5percent).Ramberg-Baecklund reaction of 12 was investigated under a variety of coditions with expectation of the formation of thiirene dioxide 11 from which generation of acenaphthyne (5) would be expected both thermally and photochemically.Observed characteristic features of the reaction are as follows: (i) the use of triethylamine as base yielded 1-bromo-acenaphthylene (20; 39percent) and debrominated products 15 (5percent) and 16 (9percent); (ii) the use of sodium methoxide as base afforded decacyclene (3) surprisingly, though in a trace amount, in addition to 20 (75percent) and acenaphthylene (18; 9percent); (iii) the use of potassium tert-butoxide as base gave an improved yield of 3 (5percent) along with 20 (36percent) and 18 (27percent).The formation of 3 may best be rationalized by assuming the generation of acenaphthyne intermediate 5 from 11 by loss of sulfur dioxide.
- Nakayama, Juzo,Ohshima, Etsuo,Ishii, Akihiko,Hoshino, Masamatsu
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- Unusual Base-induced Ring-opening Reactions of the Bis-tosylhydrazones of Dibenzobicyclooctadiene-2,3-dione and Acenaphthenequinone
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Unusual KOH-induced ring-opening reactions of the bis-tosylhydrazones of dibenzobicyclooctadiene-2,3-dione and acenaphthenequinone are described.
- Nakayama, Juzo,Segiri, Tsunehiko,Ohya, Ryuji,Hoshino, Masamatsu
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p. 791 - 792
(2007/10/02)
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