- Halogen-Adjusted Chemoselective Synthesis of Fluorene Derivatives with Position-Controlled Substituents
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Fluorenes have been synthesized through an efficient novel Pd-catalyzed tandem cross-coupling reaction; these substrates are fascinating building blocks found in organic photoelectric materials. The position of the substituent on fluorenes could be conveniently tuned by changing the halogen in the ortho-halobenzyl bromide substrates when coupled with various arylboronic acids. This newly developed synthetic approach could achieve the potential diversity in fluorene-based molecular architectures.
- Song, Juan,Sun, Wei,Li, Yali,Wei, Fuliang,Liu, Chao,Qian, Yan,Chen, Shufen
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Read Online
- Method for reducing carbonyl reduction to methylene under illumination
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The invention belongs to the technical field of organic chemical synthesis. The method comprises the following steps: (1) mixing the carbonyl compound and the amine compound in a solvent, reacting 3 - 6 under the illumination of 380 - 456 nm, the reaction system is low in toxicity, high in atom utilization rate 12 - 24h. and production efficiency, safe and controllable in reaction process and capable of simplifying the operation in the preparation and production process. At the same time, the residue toxicity of the reaction is minimized, the pollution caused by the production process to the environment is reduced, and the steps and operations of removing residues after the reaction are simplified. In addition, the reactant feedstock is readily available. The reactant does not need additional modification before the reaction, can be directly used for preparing production, simplifies the operation steps, and shortens the reaction route. The production cost is obviously reduced.
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Paragraph 0033-0038; 0054-0058
(2021/09/29)
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- Dual Gold Catalysis: Synthesis of Fluorene Derivatives from Diynes
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1,5-Diyne systems bearing one terminal and one benzyl- or allyl-substituted alkyne attached to an aromatic backbone were converted in the presence of a gold catalyst. In a dual gold-catalyzed process, gold vinylidenes are formed that selectively undergo formal CH insertion into the C(sp2)–H bond of the offered unsaturated systems. If H atoms are present in the propargylic position, a subsequent isomerization to the aromatic system takes place leading to 9H-fluorene and 11H-benzo[b]fluorene derivatives as final products. In the case of a quaternary carbon in the propargylic position no further aromatization is observed and 10H-benzo[b]fluorene derivatives are obtained in high yield. (Figure presented.).
- Bucher, Janina,Wurm, Thomas,Taschinski, Svenja,Sachs, Eleni,Ascough, David,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 225 - 233
(2017/02/05)
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- Oxygen Activated, Palladium Nanoparticle Catalyzed, Ultrafast Cross-Coupling of Organolithium Reagents
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The discovery of an ultrafast cross-coupling of alkyl- and aryllithium reagents with a range of aryl bromides is presented. The essential role of molecular oxygen to form the active palladium catalyst was established; palladium nanoparticles that are highly active in cross-coupling reactions with reaction times ranging from 5 s to 5 min are thus generated in situ. High selectivities were observed for a range of heterocycles and functional groups as well as for an expanded scope of organolithium reagents. The applicability of this method was showcased by the synthesis of the [11C]-labeled PET tracer celecoxib.
- Heijnen, Dorus,Tosi, Filippo,Vila, Carlos,Stuart, Marc C. A.,Elsinga, Philip H.,Szymanski, Wiktor,Feringa, Ben L.
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supporting information
p. 3354 - 3359
(2017/03/17)
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- Palladium-Catalyzed Formal [4 + 1] Annulation via Metal Carbene Migratory Insertion and C(sp2)-H Bond Functionalization
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A highly efficient and operationally simple palladium-catalyzed formal [4 + 1] annulation reaction has been developed. The reaction is featured by the formation of two different C-C bonds on a carbenic center. It represents a concise method for the synthesis of a wide range of polycyclic aromatic hydrocarbons (PAHs) and 1H-indenes with easily available (trimethylsilyl)diazomethane as the carbene source. Metal carbene migratory insertion and C(sp2)-H bond activation are proposed as the key steps in this transformation. The reaction further demonstrates the versatility of the carbene-based coupling in combination with various transition-metal-catalyzed transformations.
- Xu, Shuai,Chen, Ri,Fu, Zihao,Zhou, Qi,Zhang, Yan,Wang, Jianbo
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p. 1993 - 1997
(2017/08/14)
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- Au-catalyzed biaryl coupling to generate 5- to 9-membered rings: Turnover-limiting reductive elimination versus π-complexation
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The intramolecular gold-catalyzed arylation of arenes by aryl-trimethylsilanes has been investigated from both mechanistic and preparative aspects. The reaction generates 5- to 9-membered rings, and of the 44 examples studied, 10 include a heteroatom (N, O). Tethering of the arene to the arylsilane provides not only a tool to probe the impact of the conformational flexibility of Ar-Au-Ar intermediates, via systematic modulation of the length of aryl-aryl linkage, but also the ability to arylate neutral and electron-poor arenes-substrates that do not react at all in the intermolecular process. Rendering the arylation intramolecular also results in phenomenologically simpler reaction kinetics, and overall these features have facilitated a detailed study of linear free energy relationships, kinetic isotope effects, and the first quantitative experimental data on the effects of aryl electron demand and conformational freedom on the rate of reductive elimination from diaryl-gold(III) species. The turnover-limiting step for the formation of a series of fluorene derivatives is sensitive to the reactivity of the arene and changes from reductive elimination to π-complexation for arenes bearing strongly electron-withdrawing substituents (σ > 0.43). Reductive elimination is accelerated by electron-donating substituents (ρ = -2.0) on one or both rings, with the individual σ-values being additive in nature. Longer and more flexible tethers between the two aryl rings result in faster reductive elimination from Ar-Au(X)-Ar and lead to the π-complexation of the arene by Ar-AuX2 becoming the turnover-limiting step.
- Corrie, Tom J. A.,Ball, Liam T.,Russell, Christopher A.,Lloyd-Jones, Guy C.
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supporting information
p. 245 - 254
(2017/05/29)
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- Au-Catalyzed Biaryl Coupling to Generate 5- To 9-Membered Rings: Turnover-Limiting Reductive Elimination versus ?-Complexation
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The intramolecular gold-catalyzed arylation of arenes by aryl-trimethylsilanes has been investigated from both mechanistic and preparative aspects. The reaction generates 5- to 9-membered rings, and of the 44 examples studied, 10 include a heteroatom (N, O). Tethering of the arene to the arylsilane provides not only a tool to probe the impact of the conformational flexibility of Ar-Au-Ar intermediates, via systematic modulation of the length of aryl-aryl linkage, but also the ability to arylate neutral and electron-poor arenes - substrates that do not react at all in the intermolecular process. Rendering the arylation intramolecular also results in phenomenologically simpler reaction kinetics, and overall these features have facilitated a detailed study of linear free energy relationships, kinetic isotope effects, and the first quantitative experimental data on the effects of aryl electron demand and conformational freedom on the rate of reductive elimination from diaryl-gold(III) species. The turnover-limiting step for the formation of a series of fluorene derivatives is sensitive to the reactivity of the arene and changes from reductive elimination to ?-complexation for arenes bearing strongly electron-withdrawing substituents (σ > 0.43). Reductive elimination is accelerated by electron-donating substituents (ρ = -2.0) on one or both rings, with the individual σ-values being additive in nature. Longer and more flexible tethers between the two aryl rings result in faster reductive elimination from Ar-Au(X)-Ar and lead to the ?-complexation of the arene by Ar-AuX2 becoming the turnover-limiting step.
- Ball, Liam T.,Corrie, Tom J. A.,Lloyd-Jones, Guy C.,Russell, Christopher A.
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supporting information
p. 245 - 254
(2021/09/04)
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- Efficient palladium-catalyzed C(sp2)-H activation towards the synthesis of fluorenes
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A facile protocol for the synthesis of fluorene derivatives has been developed through palladium-catalyzed cyclization of 2′-halo-diarylmethanes via activation of arylic C-H bonds. The reactions occurred smoothly and allowed both electron-rich and electron-deficient substrates to convert into their corresponding fluorenes in good to excellent yields. Studies revealed that this Pd-catalyzed cyclization was also available for the substrates of 2′-chloro-diarylmethanes and no catalyst poisoning occurred for 2′-iodo-diphenylmethane.
- Song, Juan,Li, Yali,Sun, Wei,Yi, Chenglong,Wu, Hao,Wang, Haotian,Ding, Keran,Xiao, Kang,Liu, Chao
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supporting information
p. 9030 - 9033
(2016/11/11)
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- Synthesis of Fluorenes Starting from 2-Iodobiphenyls and CH2Br2 through Palladium-Catalyzed Dual C-C Bond Formation
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A facile and efficient approach is developed for the synthesis of fluorene and its derivatives starting from 2-iodobiphenyls and CH2Br2. A range of fluorene derivatives can be synthesized under relatively mild conditions. The reaction proceeds via a tandem palladium-catalyzed dual C-C bond formation sequence through the key dibenzopalladacyclopentadiene intermediates, which are obtained from 2-iodobiphenyls through palladium-catalyzed C-H activation.
- Shi, Guangfa,Chen, Dushen,Jiang, Hang,Zhang, Yu,Zhang, Yanghui
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p. 2958 - 2961
(2016/07/06)
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- Pd(0)-Catalyzed Cross-Coupling of 1,1-Diboronates with 2,2′-Dibromobiphenyls: Synthesis of 9H-Fluorenes
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An efficient and mild synthesis of 9H-fluorene derivatives through a Pd(0)-catalyzed cross-coupling reaction of 1,1-diboronates with 2,2′-dibromobiphenyls has been developed. This reaction features high yields, operational simplicity, and mild reaction conditions, thus providing an excellent alternative to published methods for 9H-fluorene synthesis.
- Xu, Shuai,Shangguan, Xianghang,Li, Huan,Zhang, Yan,Wang, Jianbo
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p. 7779 - 7784
(2015/08/18)
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- Commutative reduction of aromatic ketones to arylmethylenes/alcohols by hypophosphites catalyzed by Pd/C under biphasic conditions
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An efficient method is reported to reduce aromatic ketones selectively into arylmethylenes or alcohols with hypophosphites and Pd/C, depending on the selected conditions. This study could represent a promising alternative to the classical uses of standard hydrides or molecular hydrogen involved in reduction and deoxygenation procedures.
- Guyon, Carole,Baron, Marc,Lemaire, Marc,Popowycz, Florence,Métay, Estelle
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p. 2088 - 2095
(2014/03/21)
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- Br?nsted acid-mediated intramolecular cyclization of biaryl triazenes for the synthesis of fluorenes and 9,10-dihydro-phenanthrenes
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The efficient synthesis of fluorenes from biaryl triazenes is successfully developed. Up to 27 examples of biaryl triazenes are converted into their corresponding fluorene derivatives in the presence of CF3COOH (4.0 equiv). Mechanism research i
- Xu, Lijun,Yang, Weijun,Zhang, Lili,Miao, Maozhong,Yang, Zhigen,Xu, Xin,Ren, Hongjun
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p. 9206 - 9221
(2015/01/08)
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- Photocatalysis in dimethyl carbonate green solvent: Degradation and partial oxidation of phenanthrene on supported TiO2
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Dimethyl carbonate (DMC) is here proposed-for the first time-as a green organic solvent for photocatalytic synthesis. In this work, the photocatalytic partial oxidation of phenanthrene in dimethyl carbonate (DMC) by using anatase TiO2as the photocatalyst is described as paradigmatic example of a green synthetic process starting from polycyclic aromatic hydrocarbons (PAHs). For comparison, the same reaction carried out also in ethanol, 1-propanol or 2-propanol is reported. The use of DMC as the solvent allowed us to achieve 19% and 23% selectivity towards 9-fluorenone and 6H-benzo[c]chromen-6-one, respectively. The proposed approach may represent both a new green synthetic process and an environmentally friendly route to degradation of PAHs. This journal is
- Bellardita,Loddo,Mele,Panzeri,Parrino,Pibiri,Palmisano
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p. 40859 - 40864
(2015/01/08)
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- Direct catalytic cross-coupling of organolithium compounds
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Catalytic carbon-carbon bond formation based on cross-coupling reactions plays a central role in the production of natural products, pharmaceuticals, agrochemicals and organic materials. Coupling reactions of a variety of organometallic reagents and organic halides have changed the face of modern synthetic chemistry. However, the high reactivity and poor selectivity of common organolithium reagents have largely prohibited their use as a viable partner in direct catalytic cross-coupling. Here we report that in the presence of a Pd-phosphine catalyst, a wide range of alkyl-, aryl- and heteroaryl-lithium reagents undergo selective cross-coupling with aryl- and alkenyl-bromides. The process proceeds quickly under mild conditions (room temperature) and avoids the notorious lithium halogen exchange and homocoupling. The preparation of key alkyl-, aryl- and heterobiaryl intermediates reported here highlights the potential of these cross-coupling reactions for medicinal chemistry and material science.
- Giannerini, Massimo,Fananas-Mastral, Martin,Feringa, Ben L.
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p. 667 - 672
(2013/08/23)
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- Synthesis of fluorene and indenofluorene compounds: Tandem palladium-catalyzed suzuki cross-coupling and cyclization
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Figure Presented "Fluor" it: Palladium-catalyzed tandem reactions, in which C(sp3)-H bond activation is the key step (see scheme; DMA = dimethylacetamide), lead to substituted fluorenes and indenofluorenes through annulation in high yield and i
- Liu, Tao-Ping,Xing, Chun-Hui,Hu, Qiao-Sheng
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supporting information; experimental part
p. 2909 - 2912
(2010/08/04)
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- Highly efficient and versatile synthesis of polyarylfluorenes via Pd-catalyzed C-H bond activation
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A facile protocol for the Pd-catalyzed preparative synthesis of fluorene derivatives has been developed. While a wide range of fluorenes were easily obtained with high efficiency and selectivity under mild conditions, excellent functional group tolerance
- Hwang, Seung Jun,Kim, Hyun Jin,Chang, Sukbok
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supporting information; experimental part
p. 4588 - 4591
(2009/12/09)
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- Low-valent niobium-mediated double activation of C-F/C-H bonds: Fluorene synthesis from o-arylated α,α,α-trifluorotoluene derivatives
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By the treatment of 0.3 molar amount of NbCl5 and LiAlH4, o-arylated α,α,α-trifluorotoluenes afforded fluorene derivatives in good yields. C-F bonds of the CF3 group and the neighboring ortho C-H bond were doubly activated to give the coupling products. Copyright
- Fuchibe, Kohei,Akiyama, Takahiko
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p. 1434 - 1435
(2007/10/03)
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- Semivolatile and volatile compounds in combustion of polyethylene
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The evolution of semivolatile and volatile compounds in the combustion of polyethylene (PE) was studied at different operating conditions in a horizontal quartz reactor. Four combustion runs at 500 and 850°C with two different sample mass/air flow ratios and two pyrolytic runs at the same temperatures were carried out. Thermal behavior of different compounds was analyzed and the data obtained were compared with those of literature. It was observed that α,ω-olefins, α-olefins and n-paraffins were formed from the pyrolytic decomposition at low temperatures. On the other hand, oxygenated compounds such as aldehydes were also formed in the presence of oxygen. High yields were obtained of carbon oxides and light hydrocarbons, too. At high temperatures, the formation of polycyclic aromatic hydrocarbons (PAHs) took place. These compounds are harmful and their presence in the combustion processes is related with the evolution of pyrolytic puffs inside the combustion chamber with a poor mixture of semivolatile compounds evolved with oxygen. Altogether, the yields of more than 200 compounds were determined. The collection of the semivolatile compounds was carried out with XAD-2 adsorbent and were analyzed by GC-MS, whereas volatile compounds and gases were collected in a Tedlar bag and analyzed by GC with thermal conductivity and flame ionization detectors.
- Font, Rafael,Aracil, Ignacio,Fullana, Andrés,Conesa, Juan A.
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p. 615 - 627
(2007/10/03)
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- Preparation of indene derivatives
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A process for preparing indene derivatives of the general formula I where R1 is a C1-C10-alkyl radical, a phenyl radical or a C1-C4-alkyl-substituted phenyl radical and A is a bridge which, together with the adjacent carbons, forms a six-membered aromatic or a five- or six-membered heteroaromatic or carbocyclic ring onto which a further aromatic ring may be fused, comprises reacting II with III (X=chlorine, bromine, iodine) in the presence of a Friedel-Crafts catalyst to give IV which is then dehydrogenated to I.
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- Characterization of the combustion products of polyethylene
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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)
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Seventeen new catalyst precursors for the syndiospecific polymerization of propylene are presented. The new metallocene complexes are substituted in the positions 2 and 7 of the fluorenylidene fragment by MeO-, halogen-, alkyl-and aryl groups. The focus i
- Alt, Helmut G.,Zenk, Roland
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- Method for treating inflammation and compounds and compositions suitable for use therein
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The present invention relates to a method of treating an inflammatory condition, and to compounds and composition suitable for use in such a method, which compounds have the Formula: STR1 wherein: X is methylene, ethylene, ethyleneoxy, or oxygen; Q is STR2 where C' is a residue of a lipophilic amino acid, and Y is --CO2 H, --CH2 OH, --CONR1 R2, or --CO2 R1 where R1 and R2 hydrogen, alkyl, or aryl; R3 and R4 are, independently, hydrogen, alkyl or aryl; and A and B are, independently, hydrogen, fused phenyl, alkyl, aryl, alkaryl, aralkyl, alkoxy, alkoxyalkyl, halogen, or nitro; or pharmaceutically acceptable salts thereof.
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- An N.M.R. Investigation of the Mills-Nixon Effect
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The 4J coupling constant, previously established as a probe of bond order, was used to examine the bond orders in a series of ortho-bridged compounds: benzocyclopropene, 1,2-dihydrobenzocyclobutene, indan and tetralin.No evidence for sterically induced bond fixation (i.e. the Mills-Nixon effect) was found, but some evidence for electronic distortion in the corresponding benzylic ketones was observed.The experimental results are in accord with SCF/MO calculations.
- Collins, Michael J.,Gready, Jill E.,Sternhell, Sever,Tansey, Charles W.
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p. 1547 - 1557
(2007/10/02)
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- Structure-activity relationships of (arylalkyl)imidazole anticonvulsants: Comparison of the (fluorenylalkyl)imidazoles with nafimidone and denzimol
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A recently discovered and structurally distinct class of antiepileptic drugs is the (arylalkyl)imidazoles. Two independently discovered representatives of this class, denzimol (α-[4-(2-phenylethyl)phenyl]-1H-imidazole-1-ethanol) and nafimidone (2-(1H-imidazol-1-yl)-1-(2-naphthalenyl)ethanone), are undergoing clinical evaluation. Our structure-activity relationship (SAR) studies revealed that in addition to the naphthalenyl and phenethylphenyl aryl moieties of nafimidone and denzimol, respectively, fluorenyl, benzo[b]thienyl, and benzofuranyl aryl groups provided several highly active (arylalkyl)imidazole anticonvulsants. These structurally diverse aryl moieties, and comparable anticonvulsant activities, lend credence to the hypothesis that the pharmacophore of this class of anticonvulsants is the alkylimidazole portion of the molecule, with the lipophilic aryl portion enabling penetration of the blood-brain barrier. The authors focused their SAR studies on the (fluorenylalkyl)imidazole series. A representative compound from this series is 1-(9H-fluoren-2-yl)-2-(1H-imidazol-1-yl)ethanone. This agent was twice as potent as nafimidone in inhibiting maximal electroshock seizures in mice (po ED50's = 25 and 56 mg/kg, respectively) and considerably less toxic in the rat (po LD50's = 4550 and 504 mg/kg, respectively). The tertiary alcohol α-(9H-fluoren-2-yl)-α-methyl-1H-imidazole-1-ethanol) was as potent as denzimol in mice (po ED50's = 10 and 12 mg/kg, respectively). This series of imidazole anticonvulsants was highly selective; while many compounds displayed potent antielectroshock activity, little or no activity was observed against pentylenetetrazole-induced clonic seizures or in the horizontal screen test for ataxia. All active compounds that we tested in this series, as well as denzimol and nafimidone, potentiated hexobarbital-induced sleeping time in mice, probably by imidazole-mediated inhibition of cytochrome P-450. The SAR's for the anticonvulsant activity and the sleeping time potentiation were similar. The propensity of these (arylalkyl)imidazole anticonvulsants to interact strongly with cytochrome P-450 and thereby impair the metabolism of other antiepileptic drugs may severely limit their clinical utility as anticonvulsants.
- Robertson,Krushinski,Beedle,Leander,Wong,Rathbun
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p. 1577 - 1586
(2007/10/02)
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- Anti-convulsant fluorenylalkylimidazole derivatives, compositions, and method of use
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This invention provides for certain fluorenylalkyl imidazoles and their pharmaceutical formulations and their use as anticonvulsant agents.
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