- Gas phase formation of cyclopentanaphthalene (benzindene) isomers: Via reactions of 5- And 6-indenyl radicals with vinylacetylene
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The tricyclic polycyclic aromatic hydrocarbons (PAHs) 3H-cyclopenta[a]naphthalene (C13H10), 1H-cyclopenta[b]naphthalene (C13H10) and 1H-cyclopenta[a]naphthalene (C13H10) along with their indene-based bicyclic isomers (E)-5-(but-1-en-3-yn-1-yl)-1H-indene, (E)-6-(but-1-en-3-yn-1-yl)-1H-indene, 5-(but-3-ene-1-yn-1-yl)-1H-in-dene, and 6-(but-3-ene-1-yn-1-yl)-1H-indene were formed via a directed synthesis in a high-temperature chemical micro reactor at the temperature of 1300 ± 10 K through the reactions of the 5- and 6-indenyl radicals (C9H7) with vinylacetylene (C4H4). The isomer distributions were probed utilizing tunable vacuum ultraviolet light by recording the photoionization efficiency curves at mass-to-charge of m/z = 166 (C13H10) and 167 (13CC12H10) of the products in a supersonic molecular beam. The underlying reaction mechanisms involve the initial formation of van-der-Waals complexes followed by addition of the 5- and 6-indenyl radicals to vinylacetylene via submerged barriers, followed by isomerization (hydrogen shifts, ring closures), and termination via atomic hydrogen elimination accompanied by aromatization. All the barriers involved in the formation of 3H-cyclopenta[a]naphthalene, 1H-cyclopenta[b]naphthalene and 1H-cyclopenta[a]naphthalene are submerged with respect to the reactants indicating that the mechanisms are in fact barrierless, potentially forming PAHs via the hydrogen abstraction-vinylacetylene addition (HAVA) pathway in the cold molecular clouds such as Taurus Molecular Cloud-1 (TMC-1) at temperatures as low as 10 K. This journal is
- Ahmed, Musahid,Azyazov, Valeriy N.,Bashkirov, Eugene K.,Evseev, Mikhail M.,Howlader, A. Hasan,Kaiser, Ralf I.,Kostko, Oleg,Lu, Wenchao,Mebel, Alexander M.,Oleinikov, Artem D.,Wnuk, Stanislaw F.,Zhao, Long
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p. 22493 - 22500
(2020/11/09)
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- Synthesis of areno[e]indenes by the flash vacuum pyrolysis of 4-methoxystyrylarenes
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Flash vacuum pyrolysis of 4-methoxystyrylarenes (1b-e) at 800°C and ca. 1×10-2 Torr gave the corresponding areno[e]indenes (3b-e) as the major products and 4-hydroxystyrylarenes (4b-e) as the miner ones.
- Chu, Li-Tse,Yu, Pin-Chih,Wu, Bo-Jian,Liao, Ying-Chi,Chou, Chin-Hsing
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p. 165 - 173
(2008/02/02)
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- Aryl Radical Additions to Aldehydes and Oxime Ethers: The Tandem Enediyne-Radical Cyclization
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The previously unreported cyclization of aryl radicals onto aldehyde and oxime ether acceptors is described.The aryl radicals were generated from a cyclization of enediyne substrates.The aldehydes 6 and 9 and the oxime ethers 7 and 10 were heated to 190 deg C in chlorobenzene in the presence of 1,4-cyclohexadiene as a hydrogen atom source to yield the tandem enediyne-radical cyclization products 11a, 11b, 14, 21, and 22, and the simple enediyne cyclization products 12, 13, 15, 16, and 23.For the enediyne aldehyde substrates tandem enediyne-radical cyclization does not appear to be a synthetically useful process and a mixture of products was obtained.The aryl radicals generated in these enediyne cyclizatios subsequently undergo either a radical cyclization or other reactions such as hydrogen abstraction from 1,4-cyclohexadiene, decarbonylation, or intramolecular 1,5- and 1,6-hydrogen abstractinos.In contrast, the reactions with oxime ether precursors provide the tandem enediyne-radical cyclization products in good yield and provide a useful alternative to the tandem enediyne-6-exo-radical cyclization onto olefins.
- Grissom, Janet Wisniewski,Klingberg, Detlef
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p. 6559 - 6564
(2007/10/02)
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- Pyrolytic Generation of Aryne and Exocyclic Carbene Species: Trapping by an Adjacent o-Tolyl Group
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Flash vacuum pyrolysis of 2'-methylbiphenyl-2,3-dicarboxylic anhydride (3-o-tolylphthalic anhydride) at 860 deg/0.07 mmm gave a 1:1 mixture of 1H- and 3H-benzindene (22percent), and fluorene (49percent).The pathways leading to these products are discussed.
- Brown, Roger F. C.,Eastwood, Frank W.,Smith, Cameron J.
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p. 1315 - 1320
(2007/10/02)
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