- Reaction of stannenes and phosphastannenes with aldehydes and ketones: New tin four-membered ring derivatives
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Stannene Tip2Sn=CR2 1 (Tip = 2,4,6-triisopropylphenyl, CR2 = fluorenylidene) enters a [2+2] cycloaddition reaction with benzophenone to afford the four-membered ring derivative 2. This stannaoxetane undergoes a [2+2] decom
- Kandri Rodi,Anselme,Ranaivonjatovo,Escudié
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- Aggregation-Induced Emission Leading to White Light Emission in Diphenylbenzofulvene Derivatives
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The search for a unique molecular system able to efficiently emit in the total visible range of the electromagnetic spectra, i. e., white light emission (WLE), is a topic of intense research. We here show that aggregates formed by diphenylbenzofulvene (DP
- Rodrigues, Ana Clara B.,Peixoto, Mariana,Gomes, Carla,Pineiro, Marta,Seixas de Melo, J. Sérgio
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supporting information
(2022/01/19)
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- Palladium-catalyzed coupling reaction of 2-iodobiphenyls with alkenyl bromides for the construction of 9-(diorganomethylidene)fluorenes
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An atom economical protocol for the construction of 9-(diorganomethylidene)fluorenes through palladium-catalyzed coupling reactions of 2-iodobiphenyls with alkenyl bromides has been reported. The reaction proceeds through the C-H activation/oxidative addition/reduction elimination/intramolecular Heck coupling reaction to afford a series of 9-(diorganomethylidene)fluorenes with good yields. Control experiments demonstrate that a five-membered palladacycle acts as a key intermediate and β-H elimination serves as the rate-limiting step.
- Zhao, Ya-Heng,Wang, Jian-Long,Zhou, Yun-Bing,Liu, Miao-Chang,Wu, Hua-Yue
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supporting information
p. 8250 - 8253
(2021/10/12)
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- Synthesis of 9-Fluorenylidenes via Pd-Catalyzed C-H Vinylation with Vinyl Bromides
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A facile and efficient approach for the synthesis of 9-fluorenylidenes has been developed via the palladium-catalyzed cross-coupling of 2-iodobiphenyls and vinyl bromides. The reaction involves the C-H activation of 2-iodobiphenyls and dual C-C bond formations. A range of 9-fluorenylidene derivatives, including diphenyldibenzofulvenes, can be synthesized with the reaction.
- Yang, Shuai,Zhang, Yanghui
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supporting information
p. 7746 - 7750
(2021/10/12)
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- α-Bromoacrylic Acids as C1 Insertion Units for Palladium-Catalyzed Decarboxylative Synthesis of Diverse Dibenzofulvenes
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Herein α-bromoacrylic acids have been employed as C1 insertion units to achieve the palladium-catalyzed [4 + 1] annulation of 2-iodobiphenyls, which provides an efficient platform for the construction of diverse dibenzofulvenes. This protocol enables the formation of double C(aryl)-C(vinyl) bonds via a C(vinyl)-Br bond cleavage and decarboxylation. It is particularly noteworthy that the method features a broad substrate scope, and various interesting frameworks, such as bridged ring, fused (hetero)aromatic ring, and divinylbenzene, can be successfully incorporated into the products.
- Zhang, Minghao,Deng, Wenbo,Sun, Mingjie,Zhou, Liwei,Deng, Guobo,Liang, Yun,Yang, Yuan
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p. 5744 - 5749
(2021/08/18)
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- Ligand-Free Ru-Catalyzed Direct sp3 C-H Alkylation of Fluorene Using Alcohols
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The sp3 C-H alkylation of 9H-fluorene using alcohol and a Ru catalyst via the borrowing hydrogen concept has been described. This reaction was catalyzed by the [Ru(p-cymene)Cl2]2 complex (3 mol %) and exhibited a broad reaction scope with different alcohols, allowing primary and secondary alcohols to be employed as nonhazardous and greener alkylating agents with the formation of environmentally benign water as a byproduct. A variety of 9H-fluorene underwent selective and exclusive mono-C9-alkylation with primary alcohols in good to excellent isolated yield (26 examples, 50-92% yield), whereas this reaction with secondary alcohols in the absence of any external oxidants furnished the tetrasubstituted alkene as the major product. Furthermore, a base-mediated C-H hydroxylation of the synthesized 9H-fluorene derivatives afforded 9H-hydroxy-functionalized quaternary fluorene derivatives in excellent yield.
- Shaikh, Moseen A.,Agalave, Sandip G.,Ubale, Akash S.,Gnanaprakasam, Boopathy
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p. 2277 - 2290
(2020/02/04)
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- A novel application of 2-silylated 1,3-dithiolanes for the synthesis of aryl/hetaryl-substituted ethenes and dibenzofulvenes
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Trimethylsilyldiazomethane (TMS-CHN2) reacts readily with hetaryl thioketones to give sterically crowded 2-trimethylsilyl- 4,4,5,5-tetrahetaryl-1,3-dithiolanes with complete regioselectivity at -75 °C as well as at rt. Thiofluorenone, a relatively stable and highly reactive aryl thioketone, yields upon treatment with TMS-CHN2at -60 °C the corresponding 1,3,4-thiadiazoline. This unstable cycloadduct undergoes decomposition at ca. -45 °C and the silylated thiocarbonyl S-methanide generated thereby is trapped with complete regioselectivity by aryl or hetaryl thioketones forming also sterically crowded 2-trimethylsilyl-1,3- dithiolanes. The obtained 1,3-dithiolanes, by treatment with an equimolar amount of TBAF in a one-pot procedure, are converted in high yields into hetaryl/aryl-substituted ethenes or dibenzofulvenes, respectively, via a cycloreversion reaction of the intermediate 1,3-dithiolane carbanion. The presented protocol offers a new, highly efficient approach to tetrasubstituted ethenes and dibenzofulvenes bearing aryl and/or hetaryl substituents.
- Mloston, Grzegorz,Pipiak, Paulina,Hamera-Fa?dyga, Róza,Heimgartner, Heinz
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p. 1900 - 1906
(2017/09/27)
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- New synthesis of dibenzofulvenes by palladium-catalyzed double cross-coupling reactions
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Palladium-catalyzed double cross-coupling reactions of 1,1-bis(pinacolato) borylalk-1-enes with 2,2′-dibromobiaryls and of 9-stannafluorenes with 1,1-dibromoalk-1-enes have been demonstrated to serve as new synthetic methods for dibenzofulvenes.
- Shimizu, Masaki,Nagao, Ikuhiro,Kiyomoto, Shin-Ichi,Hiyama, Tamejiro
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p. 1277 - 1284,8
(2020/09/09)
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- Palladium catalyzed atom-economic synthesis of functionalized 9-(diarylmethylene)-9H-fluorenes using triarylbismuths in one-pot bis-coupling process
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An efficient palladium catalyzed atom-economic synthesis of functionalized 9-(diarylmethylene)-9H-fluorenes has been accomplished in one-pot bis-coupling process using triarylbismuths as organometallic reagents. These bis-couplings in 1 hour short reactio
- Rao, Maddali L.N.,Dasgupta, Priyabrata
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supporting information; experimental part
p. 162 - 165
(2012/01/30)
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- Copper-catalysed bromoalkynylation of arynes
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Arynes were found to be inserted into a C(sp)-Br σ-bond of bromoalkynes in the presence of a copper catalyst, giving (alkynyl)bromoarenes in a straightforward manner.
- Morishita, Takami,Yoshida, Hiroto,Ohshita, Joji
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supporting information; experimental part
p. 640 - 642
(2010/05/01)
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- One-pot synthesis of diarylmethylidenefluorenes and phenanthrenes by palladium-catalyzed multiple C-H bond functionalization
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Chemical equation presented A palladium-catalyzed rapid synthesis of diarylmethylidenefluorenes and phenanthrenes by multiple C-H bond activation, C-C bond formation, and Heck-type cyclization is described (see scheme).
- Thirunavukkarasu, Vedhagiri S.,Parthasarathy, Kanniyappan,Cheng, Chien-Hong
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supporting information; body text
p. 1436 - 1440
(2010/06/15)
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- Synthesis of fluorenes via the palladium-catalyzed 5-exo-dig annulation of o-alkynylbiaryls
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The direct palladium-catalyzed intramolecular hydro arylation of o-alkynylbiaryls proceeded in a highly stereoselective manner producing fluorenes 2, the products of 5-exo-dig cyclization, in excellent yields. The cascade intermolecular arylation, incorpo
- Chernyak, Natalia,Gevorgyan, Vladimir
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scheme or table
p. 1101 - 1114
(2009/12/07)
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- Practical synthesis of unsymmetrical tetraarylethylenes and their application for the preparation of [triphenylethylene-spacer-triphenylethylene] triads
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(Chemical Equation Presented) We have demonstrated that reactions of diphenylmethyllithium with a variety of substituted benzophenones produces corresponding tertiary alcohols that are easily dehydrated, without any need for purification, to produce various unsymmetrical and symmetrical tetraarylethylenes in excellent yields. The simplicity of the method allows for the preparation of a variety of ethylenic derivatives in multigram (10-50 g) quantities with great ease. The methodology was successfully employed for the preparation of various triphenylethylene (TPE)-based triads (i.e., TPE-spacer-TPE) containing polyphenylene and fluoranyl-based spacers. The ready availability of various substituted tetraarylethylenes allowed us to shed light on the effect of substituents on the oxidation potentials (Eox) of various tetraarylethylenes. Moreover, the electronic coupling among the triphenylethylene moieties in various TPE-spacer-TPE triads was briefly probed by electrochemical and optical methods.
- Banerjee, Moloy,Emond, Susanna J.,Lindeman, Sergey V.,Rathore, Rajendra
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p. 8054 - 8061
(2008/02/13)
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- A double Suzuki approach for synthesis of substituted diarylmethylidenefluorenes
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A convenient synthesis of substituted diarylmethylidenefluorene derivatives, using a double Suzuki reaction, is reported. Georg Thieme Verlag Stuttgart.
- Ramana,Kishore Reddy, Bonthu K.,Reddy, Challa Nageswara,Gonnade, Rajesh G.,Gurjar, Mukund K.
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p. 127 - 128
(2008/03/13)
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- Photochemical Pinacol Rearrangements of Unsymmetrical Diols
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The photochemical pinacol reaction of a series of nonsymmetrical 9-fluorenyl-substituted vic-diols was investigated and compared with their acid-catalyzed thermal reaction. Unlike the thermal reaction, the radiation-induced processes involve only fluorenyl cations, as is reflected in differences of product distribution between the two reactions. From the product studies, substituent migratory aptitudes are reversed in the photochemical process, suggesting that kinetic control takes place under neutral conditions unlike the acid-catalyzed thermal reactions. The presence of fluorenyl cation intermediates and their lifetimes were established by laser flash spectroscopy studies.
- Mladenova, Gabriela,Singh, Gurmit,Acton, Austin,Chen, Lie,Rinco, Olga,Johnston, Linda J.,Lee-Ruff, Edward
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p. 2017 - 2023
(2007/10/03)
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- Studies of 9-fluorenyl carbocations. Intramolecular hydride migration in a substituted 9-fluorenyl carbocation
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The substituted fluorenyl cation, 9-(diphenylmethyl)fluoren-9-yl cation (4), is formed under stable ion conditions (low temperature/strong acid) from its corresponding alcohol 3. This ion is transformed to a substituted diphenyl methyl cation 8 at ambient temperature via an apparent 1,2-hydrogen shift. Irradiation of 9-(diphenylmethyl)fluoren-9-ol in methanol gives products derived from the corresponding cation along with radical-derived products from C-C and C-O homolysis processes. The laser flash photolysis of this alcohol gave a transient corresponding to cation 4. All of the photoproducts are derived from cation 4 or radical pathways. High level MO calculations point to a high barrier (23.8 kcal mol-1) for the 1,2-hydride shift. This barrier is the consequence of the minimum energy conformation of this fluorenyl cation which is less than ideal for the periplanar geometry necessary for this process.
- Mladenova,Chen,Rodriquez,Siu,Johnston,Hopkinson,Lee-Ruff
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p. 1109 - 1114
(2007/10/03)
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- Reactions on Aromatic Olefins Induced by Aminium Salts: Protic-Acid or Radical Cation Catalyzed Processes
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Aromatic olefins by reaction with aminium salts lead, in strongly acidic reaction media, to different reaction products, arising from the intermediate formation of carbocation or radical-cation species.
- Ciminale, Francesco,Lopez, Luigi,Mele, Giuseppe
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p. 12685 - 12696
(2007/10/02)
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- Influence of Solvent and Cation on the Properties of Oxygen-containing Organic Anions. Part 4. Mechanism and Reactivity of Tetraaryloxirane Cleavage with Alkali Metals
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Six tetraaryloxiranes 1a-f (Scheme 4) were reduced (Schemes 1-3) with alkali metals (M = Li, Na, K, Cs) in eight polar aprotic solvents under an inert atmosphere.The organometallic solutions thus obtained were hydrolysed and the reaction products analysed.Similar experiments were carried out where the same solutions were quenched with D2O or MeI.In some cases the same solutions were studied by NMR and ESR spectroscopy before quenching.A stepwise reduction mechanism was established where the transfer of a first electron produces CO-bond scission in the oxirane ring, yielding a short-lived radical anion 4 or 5 (Scheme 1), i. e., a tetraalkyl-β-oxidoethyl radical.This intermediate can either eliminate oxygen as metal oxide (MO) to produce a tetraarylethylene 24 (Scheme 2) or be further reduced to a dianion 8 or 9 (Scheme 1).This anion yields, upon hydrolysis, low yields,if any, of the corresponding tetraphenylethanol 15 or 16 (Z = H).The larger proportion of the dianion, after the first protonation step, yielding anion 11 or 22, undergoes CC-bond scission which leads eventually to the corresponding ketone and diarylmethane 19 + 20 or 21 + 23 (Z = H) (Scheme 2).Other possible pathways were excluded through experiments where other possible intermediates were generated.These led to different end products.A triparametric linear correlation as a function of solvent parameters ETN and DN, as well as the cationic radius, was established for the influence of the nature of the solvent and counter-ion on the ratio between the rates of formation of products stemming from metal oxide (MO) elimination by the ring-opened radical anion 4 or 5 (Schemes 1 and 2) and rates of formation of products stemming from further reduction of the same radical anion to the dianion 8 or 9, thus confirming the mechanism established.
- Franco, M. Luisa T. M. B.,Herold, Bernardo J.,Maercker, Adalbert
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p. 119 - 129
(2007/10/02)
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- PHOSPHORORGANISCHE VERBINDUNGEN 120. VERSUCHE ZUM NACHWEIS VON "PHOSPHENEN" AUS GEEIGNETEN PHOSPHINSAEUREDERIVATEN DURCH ELIMINIERUNG
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Phosphinicacidhalogenides with the structure C are reacted with strong bases in the presence of carbonylcompounds.The eventually as intermediates formed "phosphenes" lead with carbonyl compounds to olefines following the course of the "PO-activated olefination".The intermediates don't react with olefines (stilbene or cyclopentadiene) to an isolable adduct.Key words: Phosphinicacidhalides; phosphenes as intermediates; PO-activated olefination; synthesis of olefines.
- Weidert, Peter J.,Geyer, Ekkehard,Horner, Leopold
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- Substituent Effects on Electron Spin Distribution and Conformation of Radical Ions obtained from 9-Diphenylmethylenefluorenes
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Nine new substituted 9-diphenylmethylenefluorenes were synthetized.The reductions of the unsubstituted hydrocarbon and eleven substituted derivatives were studied by cyclic voltammetry in dimethylformamide solution.E.s.r. and ENDOR spectra of the radical anions obtained by reduction with alkali metal in tetrahydrofuran were recorded.The electron spin distribution as obtained from experiment was compared with the results of Hueckel-McLachlan calculations.The conformations of the radical anions were determined from the spectra.The ratio of electron spin densities in the fluorene part of the alkene and in the diphenylmethylene group obeys a linear Hammett correlation.A similar study was performed for the radical cations of six of the twelve alkenes.
- Franco, M. Luisa T. M. B.,Herold, Bernardo J.,Evans, Jeffrey C.,Rowlands, Christopher C.
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p. 443 - 450
(2007/10/02)
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- Contributions to the Chemistry of Boron, 181. Methyleneboranes as Intermediate of an Olefin Synthesis
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Gas phase pyrolysis of fluoro(tetramethylpiperidino)boranes 1 at >= 460 deg C yields (CH3)3SiF, but no methyleneborane 2 could be detected.In solution, (CH3)3SiF is produced at 285 deg C, and in the presence of benzophenone olefins are obtained.The olefin formation is explained by Wittig-type reaction of an intermediate methyleneborane 2 with the ketone.
- Glaser, Bernhard,Noeth, Heinrich
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p. 3856 - 3858
(2007/10/02)
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