- Alumina-Mediated π-Activation of Alkynes
-
The ability to induce powerful atom-economic transformation of alkynes is the key feature of carbophilic π-Lewis acids such as gold- and platinum-based catalysts. The unique catalytic activity of these compounds in electrophilic activations of alkynes is explained through relativistic effects, enabling efficient orbital overlapping with π-systems. For this reason, it is believed that noble metals are indispensable components in the catalysis of such reactions. In this study, we report that thermally activated γ-Al2O3activates enynes, diynes, and arene-ynes in a manner enabling reactions that were typically assigned to the softest π-Lewis acids, while some were known to be triggered exclusively by gold catalysts. We demonstrate the scope of these transformations and suggest a qualitative explanation of this phenomenon based on the Dewar-Chatt-Duncanson model confirmed by density functional theory calculations.
- Akhmetov, Vladimir,Amsharov, Konstantin,Feofanov, Mikhail,Sharapa, Dmitry I.
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p. 15420 - 15426
(2021/09/30)
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- Br?nsted Acid-Catalyzed Carbonyl-Olefin Metathesis: Synthesis of Phenanthrenes via Phosphomolybdic Acid as a Catalyst
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Compared with the impressive achievements of catalytic carbonyl-olefin metathesis (CCOM) mediated by Lewis acid catalysts, exploration of the CCOM through Br?nsted acid-catalyzed approaches remains quite challenging. Herein, we disclose a synthetic protocol for the construction of a valuable polycycle scaffold through the CCOM with the inexpensive, nontoxic phosphomolybdic acid as a catalyst. The current annulations could realize carbonyl-olefin, carbonyl-alcohol, and acetal-alcohol in situ CCOM reactions and feature mild reaction conditions, simple manipulation, and scalability, making this strategy a promising alternative to the Lewis acid-catalyzed COM reaction.
- Chen, Yi,Jin, Yuan,Lin, Zhihua,Liu, Di,Shu, Mao,Tan, Jingyao,Tian, Lingfeng,Wang, Rui,Xu, Li,Zhang, Xiaoke
-
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- Methylarene-based PAH synthesis via domino cyclization of 1, 1-difluoro-1-alkenes
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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.
- Fuchibe, Kohei,Takao, Go,Takahashi, Hiroki,Ijima, Shiori,Ichikawa, Junji
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p. 2019 - 2029
(2019/12/23)
-
- Construction of Phenanthrenes and Chrysenes from β-Bromovinylarenes via Aryne Diels-Alder Reaction/Aromatization
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A highly efficient transition-metal-free general method for the synthesis of polycyclic aromatic hydrocarbons like phenanthrenes and chrysenes (and tetraphene) from β-bromovinylarenes and arynes has been developed. The reactions proceed via an aryne Diels-Alder (ADA) reaction, followed by a facile aromatization. This is the first report on direct construction of chrysenes (and tetraphene) using the ADA approach. Unlike the literature method which is limited to only 9/10-substituted derivatives, this method gives access to a wide variety of functionalized phenanthrenes.
- Singh, Vikram,Verma, Ram Subhawan,Khatana, Anil K.,Tiwari, Bhoopendra
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p. 14161 - 14167
(2019/10/28)
-
- Oxidative, Iodoarene-Catalyzed Intramolecular Alkene Arylation for the Synthesis of Polycyclic Aromatic Hydrocarbons
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A catalytic, metal-free and chemoselective oxidative intramolecular coupling of arene and alkene C?H bonds is reported. The active hypervalent iodine (HVI) reagent, generated catalytically in situ from iodotoluene and meta-chloroperoxybenzoic acid (m-CPBA), reacts with o-vinylbiphenyls to generate polyaromatic hydrocarbons in up to 95 % yield. Experimental evidence suggests the reactions proceed though vinyliodonium and, possibly, vinylenephenonium intermediates.
- Zhao, Zhensheng,Britt, Liam H.,Murphy, Graham K.
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p. 17002 - 17005
(2018/11/01)
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- Synthesis and characterization of phenanthrene derivatives with anticancer property against human colon and epithelial cancer cell lines
-
A variety of polycyclic aromatic hydrocarbons have been synthesized and structurally characterized in our laboratory. Phenanthrene derivatives were efficiently prepared in excellent yields and high purity via a two-step sequence. Heck coupling yielded the corresponding diarylethenes, followed by classical oxidative photocyclization to achieve the expected phenanthrenes. First, we envisioned to synthesize a variety of substituted phenanthrenequinones. Second, we investigated the possibility of a dibenz[a,c]phenazine formation by addition of o-phenylenediamine after completion of the oxidation process. Moreover, because phenanthrenequinones are available so simply, it is likely that other uses will be found for these compounds. For example, 9,10-phenanthrenequinone can be sequentially reduced, alkylated, acetylated, and sulfonated. All the synthesized derivatives were evaluated for cytotoxic activity in vitro against the human epidermoid carcinoma epithelial cells Hep-2 and human colon carcinoma cells Caco-2 using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. From the structure–activity point of view, position and nature of the electron donating and electron withdrawing functional groups attached to the phenanthrene skeleton may contribute to the anticancer action. Interestingly, the analysis of the IC50 values suggests that most compounds exerted cytotoxic effects with selectivity against both cancer cells. Among them, methyl 8-methyl-9,10-phenanthrenequinone-3-carboxylate 11d showed the highest potency with IC50 values of 2.81 and 0.97 μg/mL.
- Guédouar, Habiba,Aloui, Faouzi,Beltifa, Asma,Ben Mansour, Hedi,Ben Hassine, Béchir
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p. 841 - 849
(2017/06/20)
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- Further insight into the photochemical behavior of 3-aryl-N-(arylsulfonyl)propiolamides: tunable synthetic route to phenanthrenes
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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.
- Chen, Ming,Zhao, Xinxin,Yang, Chao,Wang, Yanpei,Xia, Wujiong
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p. 12022 - 12026
(2017/03/01)
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- Systematic investigations on fused π-system compounds of seven benzene rings prepared by photocyclization of diphenanthrylethenes
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We studied the photoproducts of 1-(n-phenanthryl)-2-(m-phenanthryl)ethenes (nEm; n, m = 1, 3 and 9) for understanding photocyclization patterns based on NMR spectroscopy. The crystal structures of the photoproducts were analyzed by X-ray crystallography, and the photophysical features of the photocyclized molecules were investigated based on emission and transient absorption measurements. Phenanthrene derivatives substituted at the 1- and 3-positions were prepared for synthesizing nEm by photocyclization of stilbene derivatives. We obtained four types of primary photoproducts (n@m) from the corresponding nEm. Two of them were found to have racemic molecular structures in the single crystal determined by X-ray crystallography. Besides the primary photoproducts, two types of secondary photoproducts (n@mPP) were isolated. Fluorescence quantum yields and lifetimes of the obtained photoproducts were determined in solution whereas the definite fluorescence quantum yields were obtained in the powder. Observation of the triplet-triplet absorption spectra in solution by laser photolysis techniques showed that intersystem crossing to the triplet state competes with the fluorescence process.
- Fujino, Shota,Yamaji, Minoru,Okamoto, Hideki,Mutai, Toshiki,Yoshikawa, Isao,Houjou, Hirohiko,Tani, Fumito
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p. 925 - 934
(2017/07/10)
-
- Air-Driven Potassium Iodide-Mediated Oxidative Photocyclization of Stilbene Derivatives
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A new method has been developed for the potassium iodide-mediated oxidative photocyclization of stilbene derivatives. Compared with conventional iodine-mediated oxidative photocyclization reactions, this new method requires shorter reaction times and affords cyclized products in yields of 45-97%. This reaction proceeds with a catalytic amount of potassium iodide and works in an air-driven manner without the addition of an external scavenger. The radical-mediated oxidative photocyclization of stilbene derivatives using TEMPO was also investigated.
- Matsushima, Tomoya,Kobayashi, Sayaka,Watanabe, Soichiro
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p. 7799 - 7806
(2016/09/09)
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- Intramolecular carbonyl-ene reactions in the synthesis of peri-oxygenated hydroaromatics
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2-Methallyl aromatic aldehydes, synthesized by Suzuki coupling of 2-formylphenylboronic acids, are shown to provide cycloalkylidene ene products under acidic conditions. Susceptibility of the products to aromatization is manoeuvred by varying the reaction conditions and catalysts including binol-derived Br?nsted acid catalysts. A peri-effect is identified as a controlling factor for the aromatizations. Several oxidative transformations of an ene product are carried out as model studies of hydroaromatic polyketide natural products.
- Basak, Shyam,Mal, Dipakranjan
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p. 1758 - 1772
(2018/03/29)
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- Bismuth-catalyzed synthesis of polycyclic aromatic hydrocarbons (PAHs) with a phenanthrene backbone via cyclization and aromatization of 2-(2-arylphenyl)vinyl ethers
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The reaction of 2-(2-arylphenyl)vinyl ethers in the presence of a catalytic amount of bismuth(III) triflate gave substituted phenanthrenes in excellent yields under mild reaction conditions. The reaction was also applied to the construction of other polycyclic aromatic hydrocarbons (PAHs), such as chrysene, helicene, and pyrene having a phenanthrene backbone, via regioselective cyclization. This method has the advantages of easy availability of the cyclization precursors, operational simplicity, and high reaction efficiency.
- Murai, Masahito,Hosokawa, Naoki,Roy, David,Takai, Kazuhiko
-
supporting information
p. 4134 - 4137
(2014/09/30)
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- Continuous flow photocyclization of stilbenes-scalable synthesis of functionalized phenanthrenes and helicenes
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A continuous flow oxidative photocyclization of stilbene derivatives has been developed which allows the scalable synthesis of backbone functionalized phenanthrenes and helicenes of various sizes in good yields.
- Lefebvre, Quentin,Jentsch, Marc,Rueping, Magnus
-
supporting information
p. 1883 - 1890
(2013/10/22)
-
- Synthesis of phenanthrenes by cationic chromium(III) porphyrin-catalyzed dehydration cycloaromatization
-
Readily available biphenyl derivatives with ortho oxirane moiety react in the presence of cationic chromiun(III) porphyrin catalyst to afford phenanthrenes. The reaction is considered to be triggered by activation of the oxirane moiety through coordination to the Lewis acidic cationic chromium to give aldehyde via 1,2-hydride shift, which reacts with arene through intramolecular electrophilic aromatic substitution and subsequent dehydration. The reaction allows constructing a variety of polycyclic aromatic and heteroaromatic compounds.
- Wakabayashi, Ryota,Kurahashi, Takuya,Matsubara, Seijiro
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supporting information
p. 2297 - 2301
(2013/11/06)
-
- Straightforward synthesis of phenanthrenes from styrenes and arenes
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Semi-one-pot synthesis of phenanthrenes from styrenes and arenes was developed through cross-dehydrogenative coupling. A sequence of Heck-type coupling and photo-cyclization were involved and a variety of functionalities were tolerated. This method provides an effective and practical protocol towards the synthesis of substituted phenanthrenes. The Royal Society of Chemistry 2012.
- Li, Hu,He, Ke-Han,Liu, Jia,Wang, Bi-Qin,Zhao, Ke-Qing,Hu, Ping,Shi, Zhang-Jie
-
supporting information; experimental part
p. 7028 - 7030
(2012/08/07)
-
- Synthesis of phenanthrene and alkyl phenanthrenes by palladium(0)-catalyzed pericyclic reactions
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Palladium-catalyzed pericyclic reactions have been developed for the synthesis of phenanthrenes. This method is also useful for the synthesis of monoalkyl and dialkyl phenanthrene derivatives. Georg Thieme Verlag Stuttgart.
- Jana, Rathin,Biswas, Anup,Samanta, Shubhankar,Ray, Jayanta K.
-
scheme or table
p. 2092 - 2100
(2010/08/20)
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- Palladium-catalyzed intramolecular C-H activation: A synthetic approach towards polycyclic aromatic hydrocarbons
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A simple and convenient synthetic protocol for the construction of polycyclic aromatic hydrocarbons has been developed. A variety of phenanthrene, benzo[c]phenanthrene and chrysene derivatives was synthesized via Pd-catalyzed intramolecular C-H activation followed by acid-catalyzed water elimination.
- Paul, Sunanda,Jana, Rathin,Ray, Jayanta K.
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experimental part
p. 1463 - 1468
(2010/08/20)
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- Reaction of benzyne with styrene oxide: Insertion of arynes into a C-O bond of epoxides
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Benzyne inserts into one of the C-O bonds of styrene oxide to form a dihydrobenzofuran as the major product together with five other reaction products. A detailed study of the reaction mixture clarified an intriguing forty-year-old personal communication from Stiles and Haag. Georg Thieme Verlag Stuttgart.
- Beltrán-Rodil, Sandra,Pe?a, Diego,Guitián, Enrique
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p. 1308 - 1310
(2008/02/07)
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- Synthesis of substituted phenanthrenes via intramolecular condensation based on temperature-dependent deprotonation using a weak carbonate base
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Construction of substituted phenanthrenes via intramolecular condensation of 2′-methylbiphenyl-2-carbaldehydes using a mild base at 200 °C is described. The required high temperature can be quickly reached and easily maintained using microwave flash heating. Georg Thieme Verlag Stuttgart.
- Monsieurs, Katrien,Rombouts, Geert,Tapolcsányi, Pál,Mátyus, Péter,Maes, Bert U. W.
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p. 3225 - 3230
(2008/09/17)
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- Synthesis of the novel conjugated ω,ω′-diaryl/heteroaryl hexatriene system with the central double bond in a heteroaromatic ring: photochemical transformations of 2,3-divinylfuran derivatives
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New β,β′-aryl/heteroaryl 2,3-divinylfuran derivatives (9a-d) in which a hexatriene system is a part of heteroaromatic ring have been synthesized and their photochemical properties were investigated. The primary process observed was the isomerization to trans,trans-isomers 9a-d followed by photochemical rearrangement of the furan ring giving the phototransposition products (I-IV). Stilbenes (20, 21) and phenanthrenes (22, 25, and 26), formed as secondary products from the competitive intermolecular cycloadditions, were also observed.
- ?kori?, Irena,Flegar, Ivana,Marini?, ?eljko,?indler-Kulyk, Marija
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p. 7396 - 7407
(2007/10/03)
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- Hydrous pyrolysis of methylphenanthrenes - Degradation and isomerization
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A simulation of the chemical transformations of methylphenanthrenes in sediment was performed using hydrous pyrolysis technique. The results indicate that isomerization is not the primary cause of the change in the MPI1 index. Rather, the degradation reaction of methylphenanthrenes to phenanthrene is one of the most likely causes reversing the trend of the MPI1 index with increasing the heating temperature. An unusual isomerization between 2-methylphenanthrene and 9-methylphenanthrene was also observed during the course of heating experiments. A plausible mechanism involving [1,5]-methyl shift was proposed for this isomerization reaction.
- Wu, Suh-Huey,Wang, Yane-Shih,Fan, Lian-Xin,Robert, T. D. Chang,Huang, Ded-Shih
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p. 315 - 317
(2007/10/03)
-
- A new parameter for maturity determination of organic matter in sediments based on the clay-catalyzed thermal isomerization of monomethylphenanthrenes
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Monomethylphenanthrenes (MPs) were isomerized by heating in the presence of Na-montmorillonite at 250 - 400 °C. Isomerization between 1- and 2-MP was found to proceed faster than those between the other sets of MPs. On the basis of this facile interconversion, the molar ratio of 1- to 2-MP was suggested to be a useful new parameter for the maturity assessment of sedimentary organic matter. This parameter was tested in a geochemical study on Miocene to Pliocene sediments in the Shinjo basin of Yamagata Prefecture. We determined the molar ratio in 12 depth-differing sediments, and found an almost linearly decreasing trend in the ratio with increasing depth, showing a good correlation of this parameter to the maturity of the sedimentary organic matter.
- Nomoto, Shinya,Hagiwara, Masayosi,Nakano, Yoshinobu,Shimoyama, Akira
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p. 1437 - 1443
(2007/10/03)
-
- Evaluation of acute toxicity and genotoxicity of liquid products from pyrolysis of Eucalyptus grandis wood
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Slow pyrolysis of Eucalyptus grandis wood was performed in an oven laboratory, and smoke was trapped and condensed to yield liquid products. Polycyclic aromatic hydrocarbons (PAHs) and phenolic fractions were isolated from the former liquid products using adsorption column chromatography (ACC) and identified by GC/MS. Concentrations of PAH and phenolic fractions in total pyrolysis liquids were respectively 48.9 μg/g and 8.59% (w/w). Acute toxicity of total samples of pyrolysis liquids and the phenolic fraction was evaluated by means of two bioassays, namely, 24-h immobilization bioassay with Daphnia magna and Microtox(TM) bioassays, the latter employing the luminescent bacteria Photobacterium phosphoreum. Total pyrolysis liquids and the PAH fraction were evaluated for genotoxicity by the Microtox(TM) bioassay conducted using rehydrated freeze-dried dark mutant of the luminescent bacteria Vibrio fisheri strain M169. Total pyrolysis liquids and the phenolic fraction, respectively, in concentrations of 170 and 68 mg/L were able to immobilize 50% (EC50) of the D. magna population following 24-h exposure. Concentrations of 19 and 6 mg/L, respectively, for total pyrolysis liquids and phenolic fraction were the effective concentrations that resulted in a 50% (EC50) reduction in light produced by bacteria in the Microtox(TM) bioassay. Accordingly, the Microtox(TM) bioassay was more sensitive to toxic effects of both kind of samples than the D. magna bioassay, particularly for the phenolic fraction. Regarding to the genotoxicity evaluation, the results achieved by Microtox(TM) bioassay showed that total pyrolysis liquids had no genotoxic effects with and without exogenous metabolic activation using rat liver homogenate (S9). However, the PAH fraction showed toxic effects with rat liver activation and had a dose-response number (DRN) equal to 1.6, being in this way suspected genotoxic. The lowest detected concentration (LDC) of the PAH fraction able to cause genotoxic effects was 375 μg/L.
- Pimenta,Bayona,Garcia,Solanas
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p. 169 - 175
(2007/10/03)
-
- Characterization of the combustion products of polyethylene
-
Polyethylene (PE) was burned in a tube-type furnace with an air flow at a temperature of 600~900°C. Combustion products were collected with glass wool, glass fiber filter, and XAD-2 adsorbent. The analysis of the products was performed with GC-FID and GC-MSD. At low temperature, hydrocarbons were the major components, while at higher temperature the products were composed of polycyclic aromatic hydrocarbons. With the high performance of the Hewlett-Packard 6890GC-5973MSD, more compounds were identified in comparison with previous studies.
- Piao, Mingjun,Chu, Shaogang,Zheng, Minghui,Xu, Xiaobai
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p. 1497 - 1512
(2007/10/03)
-
- Characterization of polycyclic aromatic hydrocarbon particulate and gaseous emissions from polystyrene combustion
-
The partitioning of polycyclic aromatic hydrocarbons (PAHs) between the particulate and gaseous phases resulting from the combustion of polystyrene was studied. A vertical tubular flow furnace was used to incinerate polystyrene spheres (100-300 μm) at different combustion temperatures (800- 1200 °C) to determine the effect of temperature and polystyrene feed size on the particulate and gaseous emissions and their chemical composition. The furnace reactor exhaust was sampled using real-time instruments (differential mobility particle sizer and/or optical particle counter) to determine the particle size distribution. For chemical composition analyses, the particles were either collected on Teflon filters or split into eight size fractions using a cascade impactor with filter media substrates, while the gaseous products were collected on XAD-2 adsorbent. Gas chromatography/mass spectroscopy (GC/MS) was used to identify and quantify the specific PAH species, their partitioning between the gas and particulate phases, and their distribution as a function of emission particle size. The total mass and number of PAH species in both the particulate and gas phases were found to decrease with increasing incineration temperature and decreasing polystyrene feed size, while the mean diameter of the particles increases with increasing incineration temperature and decreasing feed size. In addition, the PAH species in the particulate phase were found to be concentrated in the smaller aerosol sizes. The experimental results have been analyzed to elucidate the formation mechanisms of PAHs and particles during polystyrene combustion. The implications of these results are also discussed with respect to the control of PAH emissions from municipal waste-to-energy incineration systems. The partitioning of polycyclic aromatic hydrocarbons (PAHs) between particulate and gaseous phases resulting from the combustion of polystyrene was studied. A vertical tubular flow furnace was used to incinerate polystyrene spheres to determine the effect of temperature and polystyrene feed size on the particulate and gaseous emissions and their chemical composition. The furnace reactor exhaust was sampled using real-time instruments to determine the particle size distribution. The total mass and number of PAH species in both the particulate and gas phases were found to decrease with increasing incineration temperature and decreasing polystyrene feed size, while the mean diameter of the particles increases with increasing incineration temperature and decreasing feed size. In addition, the PAH species in the particulate phase were found to be concentrated in the smaller aerosol sizes.
- Durlak, Susan K.,Biswas, Pratim,Shi, Jichun,Bernhard, Mary Jo
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p. 2301 - 2307
(2007/10/03)
-
- The Regioselective Methylation of Polycyclic Aromatic Hydrocarbons through Tricarbonylchromium Coordination
-
Deprotonation, methylation, and air oxidation of polycyclic arenes coordinated to chromium(0), (η6-arene)Cr(CO)3, produced ring-methylated products with high selectivity and in good yield. This procedure gave 3-methylbenz[a]anthracene from (η6-benz[a]anthracene)Cr(CO)3, 3-methylphenanthrene from (η6-phenanthrene)Cr(CO)3, 2-acetyl-6-methylphenanthrene from (η6-2-acetylphenamhrene)Cr(CO)3, and 3,7,12-trimethylbenz[a]anthracene from (η6-7,12-dimelhylbenz[a]anthracene)Cr(CO)3.
- Own,Chiu, Li-Ting
-
p. 707 - 710
(2007/10/03)
-
- Tandem acylation-cycloalkylation: A novel synthesis of phenanthrenes
-
Cyclohexene-1-acetic acid (1) undergoes reaction with various aromatic substrates 2a-k in the presence of polyphosphoric acid (PPA) to give 1,2,3,4,4a,10a-hexahydrophenanthren-9(10H)-ones 3a-k by tandem acylation-cycloalkylation, which on dehydrogenation with Pd-C afforded the corresponding phenanthrenes 4a-k in high yields.
- Ramana,Potnis, Prashant V.
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p. 1090 - 1092
(2007/10/03)
-
- Photochemistry of β-(5-Substituted-2-furyl)-o-divinylbenzenes; Substituent Effects on the Reaction Course
-
Irradiation of 2-[2-(2-vinylphenyl)ethenyl]furan (1a) and 5-methyl-2-[2-(2-vinylphenyl)ethenyl]furan (1b) gave 9,10-dihydro-4,9-methano-4H-benzo[4,5]cyclohepta[1,2-b]furan (2a) and 9,10-dihydro-2-methyl-4,9-methano-4H-benzo[4,5]cyclohepta[1,2-b]furan (2b), respectively, in a very good yield in addition to traces of 5. Contrary to these results, the 5-substituted furan derivatives 1 (c: R = CN; d: R = p-C6H4CH3, e: R = OCH3) gave mainly, upon irradiation under the same conditions, isomerization about the double bond, high-molecular-weight products, small amount of phenanthrenes 5 and only traces of bicyclic structure 2.
- Sindler-Kulyk, Marija,Kragol, Goran,Piantanida, Ivo,Tomsic, Slavica,Cvijin, Irena Vujkovic,Marinic, Zeljko,Metelko, Biserka
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p. 1593 - 1602
(2007/10/03)
-
- Flow-vacuum pyrolysis of polycyclic compounds. 9. Pyrolysis of 5H-dibenzo[a,c]cycloheptene
-
The flow-vacuum pyrolysis of the title hydrocarbon 1, studied between 500°C and 750°C at l Torr, afforded 9-methylphenanthrene as first and main reaction product along with smaller quantities of phenanthrene (2), 3-methylphenanthrene and a dimetric hydrocarbon 9. The results are compared with those obtained by Pomerantz in the pyrolysis of 1 in a static system. The reaction mechanism, possibly involving a degenerate thermal reaction 1 + 2 ? 2+ + 1 is discussed.
- Banciu, Mircea D.,Banciu, Anca,Cira, Ovidiu,Enescu, Rodica,Petride, Auriga
-
p. 329 - 336
(2007/10/03)
-
- A New Parameter for Maturity Assessment of Organic Materials in Sediments Based on Thermal Isomerization of Monomethylphenanthrenes
-
Monomethylphenanthrenes(MPs) were isomerized by heating in the presence of Na-montmorillonite to give a mixture of four isomers (1-, 2-, 3-, and 9-MP).The ratio of 1- and 2-MP produced from each isomer reached a constant value after appropriate time of heating.The ratio provides a new parameter for maturity assessment of sedimentary organic materials.
- Shimoyama, Akira,Nakano, Yoshinobu,Nomoto, Shinya
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p. 1917 - 1920
(2007/10/02)
-
- Preparation and Properties of New Methano-Bridged Dibenzophenanthrenes
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Intramolecular Friedel-Crafts alkylation of 1-(hydroxymethyl)helicenes 1-R and 15-Me leads to 10,11-methano-bridged dibenzophenanthrenes 2-R and 16-Me, respectively.These molecules are shaped like the back of a turtle as shown by X-ray crystal structure analysis.Their nonplanarity, however, is not rigid, as revealed by the temperature dependence of their (1)H-NMR spectra.With inversion barriers of about 62.4 and 67.1 kJ mol1- 2-H and 2-Me are surprisingly flexible.A remarkable diastereoselectivity is observed in the addition of methyl- and phenylmagnesium bromide to 1-formylhelicenes 14-Me leading to secondary alcohols 15a,b-Me, which cyclize to bridged hydrocarbons 16a,b-Me, in which the substituents R = Me, Ph are in the thermodynamically less favorable endo-position.Upon heating, endo-16a,b-Me isomerize to exo-16a,b-Me irreversibly. Key Words: Helicenes, methano-bridged/ Aromatic hydrocarbons, polycyclic/ Cycloheptatriene, all-benzoanellated, flexibility of/ Distorted aromatic rings
- Puls, Carsten,Stolle, Andreas,Meijere, Armin de
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p. 1635 - 1642
(2007/10/02)
-
- Cycloaromatization of α-oxoketene dithioacetals and β-oxodithioacetals with benzyl-,1-(naphthylmethyl) and 2-(naphthylmethyl)magnesium halides: Synthesis of condensed polynuclear aromatic hydrocarbons
-
An efficient route for the synthesis of substituted naphthalenes, phenanthrenes and other polynuclear aromatic hydrocarbons has been developed. The methodology involves 1,2- (or sequential 1,4- and 1,2-) addition of either benzyl, 1-(naphthylmethyl) or 2-(naphthylmethyl) magnesium halides to α-oxoketene dithioacetals or β-oxodithioacetals followed by borontrifluoride etherate catalyzed cycloaromatization of the resulting carbinols.
- Srinivasa Rao,Balu, Maliakel P.,Ila, Hiriyakkanavar,Junjappa, Hiriyakkanavar
-
p. 3499 - 3510
(2007/10/02)
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- FORMATION OF 3-METHYLPHENANTHRENE IN THE CHARGE-TRANSFER COMPLEX BETWEEN cis-4-METHYLSTILBENE AND p-CHLORANIL
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The charge-transfer complex between cis-4-methylstilbene and chloranil gives 3-methylphenanthrene when boiled in pentane (without irradiation).The structure of the product was confirmed by the data from x-ray crystallographic analysis.
- Todres, Z. V.,Dyusengaliev, K. I.,Buzlanova, M. M.,Shklover, V. E.,Struchkov, Yu. T.
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p. 724 - 726
(2007/10/02)
-
- An Unusual Fluorine Atom Rearrangement in the Photocyclization of 1-Fluorohelicenes
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Oxidative photocyclization of 1-fluorohelicene and two of its chlorine-substituted derivatives leads to the formation of 8-fluorobenzoperylenes through an unprecedented inter-ring fluorine atom migration; photoelimination of HF to give benzoperylenes also occurs as a competing process.The rearrangement pathway predominates when the irradiation is carried out at 0 deg C in air-saturated benzene solution containing 10 -3 M iodine; the elimination pathway predominates at higher temperatures or in the absence of either oxygen or iodine.The rearrangement isrationalized by postulating a triplet-state photocyclization to give a dihydrobenzoperylene intermediate, followed by abstraction of the tertiary hydrogen atom from that intermediate to give a radical that subsequently undergoes a fluorine atom shift by an SNi'mechanism.
- Mallory, Frank B.,Mallory, Clelia W.
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p. 526 - 532
(2007/10/02)
-
- The Anisotropic Effect of 4-Subsituents on the 1H NMR Chemical Shift of H-5 in Phenantrenes
-
Chloro-, methoxy- and methyl-substituents in the 4-position of phenantrenes exert a profound and diagnostic influence on the 1H chemical shift of H-5, and from 13C measurments it is considered to be due to an anisotropic effect.
- Letcher, R. M.
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p. 220 - 223
(2007/10/02)
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