195-19-7Relevant articles and documents
Aromatic hydrocarbon growth from indene
Lu, Mingming,Mulholland, James A.
, p. 625 - 633 (2001)
Aromatic hydrocarbon growth from indene (C9H8), which contains the five-membered ring cyclopentadienyl moiety, was investigated experimentally in a 4 s flow reactor over a temperature range 650-850°C. Major products observed were three C18H12 isomers (chrysene, benz[a]anthracene and benzo[c]phenanthrene), two C17H12 isomers (benzo[a]fluorene and benzo[b]fluorene), and two C10H8 isomers (naphthalene and benzofulvene). Reaction pathways to these products are proposed. Indenyl radical addition to indene produces a resonance-stabilized radical intermediate which further reacts by one of two routes. Rearrangement by intramolecular addition produces a bridged structure that leads to the formation of C17H12 and C10H8 products. Alternatively, β scission produces biindenyl, which leads to the formation of C18H12 products by a ring condensation mechanism analogous to that proposed for cyclopentadiene-to-naphthalene conversion. Temperature dependencies of both the partitioning between these two routes and the product isomer distributions are consistent with thermochemical modeling using semi-empirical molecular orbital methods. The results further illustrate the role of resonance-stabilized radical rearrangement in aromatic growth and condensation of systems with cyclopentadienyl moieties.
Cyclisation of Stilbenes to Phenanthrenes by Flash Vacuum Pyrolysis
Plater, M. John
, p. 801 - 802 (1994)
Flash Vacuum Pyrolysis of the stilbene derivatives 3,4,6 and 7 gives the corresponding phenanthrenes in reasonable yields.
Synthesis of 1-(2-ethynyl-6-methylphenyl)- and 1-(2-ethynyl-6-methoxyphenyl)-naphthalene and their cyclization
Storch, Jan,?ermák, Jan,Karban, Jind?ich
, p. 6814 - 6816 (2007)
A Suzuki cross-coupling reaction of hindered 2-bromo-1-trimethylsilylethynylbenzenes with 1-naphthaleneboronic acid yielding (2-ethynylphenyl)naphthalenes has been achieved. Their subsequent cyclization was carried out, giving benzo[c]phenanthrenes, without the use of photochemical procedures.
Water Docking Bias in [4]Helicene
Domingos, Sérgio R.,Martin, Kévin,Avarvari, Narcis,Schnell, Melanie
supporting information, p. 11257 - 11261 (2019/07/12)
We report on the one- and two-water clusters of [4]helicene, the smallest polycyclic aromatic hydrocarbon with a helical sense, which were captured in the gas phase using high-resolution rotational spectroscopy. The structures of the complexes are unambiguously revealed using microwave spectra of isotopically enriched species. In the one-water cluster, the apparent splitting pattern is consistent with a tunneling motion that encompasses an exchange of strongly and weakly bonded water hydrogens. This motion is “locked” in the two-water cluster. The relevant intermolecular contacts, symmetry, and aromaticity effects are unveiled for the microsolvated chiral topologies. These observations entail the first glance at the structures and internal dynamics of the water binding motifs of a chiral polycyclic aromatic hydrocarbon.
Methylarene-based PAH synthesis via domino cyclization of 1, 1-difluoro-1-alkenes
Fuchibe, Kohei,Takao, Go,Takahashi, Hiroki,Ijima, Shiori,Ichikawa, Junji
, p. 2019 - 2029 (2019/12/23)
Polycyclic aromatic hydrocarbons (PAHs) containing 4-7 benzene rings were synthesized via a methylarene-based protocol. Trimethyl[2-(trifluoromethyl)allyl]silane was electrophilically benzylated with Ar1CH2Br (prepared from Ar1CH3) to afford 2-trifluoromethyl-1-alkenes that were in turn nucleophilically benzylated with Ar2CH2Li (prepared from Ar2CH3) through an SN2-type reaction to produce 1, 1-difluoroethylenes, which are cyclization precursors bearing two 2-arylethyl groups. Magic acid efficiently promoted the domino FriedelCrafts-type cyclization of these precursors, followed by dehydrogenation that enabled the connection among two aryl groups (Ar1 and Ar2) by forming two benzene rings between them, facilitating the synthesis of the desired higher-order PAHs. With the proposed protocol, the combination of even a limited number of methylarenes can yield a variety of PAHs in diverse configurations.
Polycyclic Aromatic Hydrocarbons via Iron(III)-Catalyzed Carbonyl-Olefin Metathesis
McAtee, Christopher C.,Riehl, Paul S.,Schindler, Corinna S.
supporting information, p. 2960 - 2963 (2017/03/11)
Polycyclic aromatic hydrocarbons are important structural motifs in organic chemistry, pharmaceutical chemistry, and materials science. The development of a new synthetic strategy toward these compounds is described based on the design principle of iron(III)-catalyzed carbonyl-olefin metathesis reactions. This approach is characterized by its operational simplicity, high functional group compatibility, and regioselectivity while relying on FeCl3 as an environmentally benign, earth-abundant metal catalyst. Experimental evidence for oxetanes as reactive intermediates in the catalytic carbonyl-olefin ring-closing metathesis has been obtained.
Further insight into the photochemical behavior of 3-aryl-N-(arylsulfonyl)propiolamides: tunable synthetic route to phenanthrenes
Chen, Ming,Zhao, Xinxin,Yang, Chao,Wang, Yanpei,Xia, Wujiong
, p. 12022 - 12026 (2017/03/01)
Reported herein is further insight into the photochemical behaviour of 3-aryl-N-(arylsulfonyl)-propiolamides, which provides a straightforward way to access meaningful phenanthrenes. Mechanistic investigation indicated that aryl migration, C-C coupling, 1,3-hydrogen shift, desulfonylation and elimination were involved in the process. Moreover, this protocol allowed for scale-up using a flow reactor.
Facile Synthesis of Polycyclic Aromatic Hydrocarbons: Br?nsted Acid Catalyzed Dehydrative Cycloaromatization of Carbonyl Compounds in 1,1,1,3,3,3-Hexafluoropropan-2-ol
Fujita, Takeshi,Takahashi, Ikko,Hayashi, Masaki,Wang, Jingchen,Fuchibe, Kohei,Ichikawa, Junji
supporting information, p. 262 - 265 (2017/01/24)
The cycloaromatization of aromatic aldehydes and ketones was readily achieved by using a Br?nsted acid catalyst in 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP). In the presence of a catalytic amount of trifluoromethanesulfonic acid, biaryl-2-ylacetaldehydes and 2-benzylbenzaldehydes underwent sequential intramolecular cationic cyclization and dehydration to afford phenacenes and acenes, respectively. Furthermore, biaryl-2-ylacetaldehydes bearing a cyclopentene moiety at the α-position underwent unprecedented cycloaromatization including ring expansion to afford triphenylenes. HFIP effectively promoted the cyclizations by suppressing side reactions presumably as a result of stabilization of the cationic intermediates.
1,7-Naphthodiyne: A new platform for the synthesis of novel, sterically congested PAHs
Pozo, Iago,Cobas, Agustín,Pe?a, Diego,Guitián, Enrique,Pérez, Dolores
supporting information, p. 5534 - 5537 (2016/05/09)
The synthesis of an efficient precursor of the novel 1,7-naphthodiyne synthon is reported. Preliminary experiments demonstrate the usefulness of this platform for the synthesis of sterically congested polyarenes, such as helicenes and angularly fused acene derivatives. Furthermore, a novel intramolecular aryne trapping reaction is described.
Microwave flash pyrolysis: C9h8 interconversions and dimerisations
Ajaz, Aida,Voukides, Alicia C.,Cahill, Katharine J.,Thamatam, Rajesh,Skraba-Joiner, Sarah L.,Johnson, Richard P.
, p. 1301 - 1308 (2014/11/07)
The pyrolysis of 2-ethynyltoluene, indene, fluorene, and related compounds has been studied by sealed tube microwave flash pyrolysis (MFP), in concert with modelling of putative mechanistic pathways by density functional theory (DFT) computations. In the MFP technique, samples are admixed with graphite and subjected to intense microwave power (150-300 W) in a quartz reaction tube under a nitrogen atmosphere. The MFP reaction of 2-ethynyltoluene gave mostly indene, the product of a Roger Brown rearrangement (1,2-H shift to a vinylidene) followed by insertion. An additional product was chrysene, the likely result of hydrogen atom loss from indene followed by dimerisation. The intermediacy of dimeric bi-indene structures was supported by pyrolysis of bi-indene and by computational models. Benzo[a]anthracene and benzo[c]phenanthrene are minor products in these reactions. These are shown to arise from pyrolysis of chrysene under the same MFP conditions. MFP reaction of fluorene gave primarily bi-fluorene, bifluorenylidene, and dibenzochrysene, the latter derived from a known Stone-Wales rearrangement.
