- Selenenate Anions (PhSeO?) as Organocatalyst: Synthesis of trans-Stilbenes and a PPV Derivative
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The selenenate anion (RSeO?) is introduced as an active organocatalyst for the dehydrohalogen coupling of benzyl halides to form trans-stilbenes. It is shown that RSeO? is a more reactive catalyst than the previously reported sulfur analogues (sulfenate anion, RSO?) and selenolate anions (RSe?) in the aforementioned reaction. This catalytic system was also applied to the benzylic-chloromethyl-coupling polymerization (BCCP) of a bis-chloromethyl arene to form ppv (poly(p-phenylene vinylene))-type polymers with high yields, Mn (average molecular weight) up to 13,000 and ? (dispersity) of 1.15. (Figure presented.).
- Zheng, Zhipeng,Trofymchuk, Oleksandra S.,Kurogi, Takashi,Varela, Elena,Mindiola, Daniel J.,Walsh, Patrick J.
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supporting information
p. 659 - 666
(2020/01/02)
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- Catalytic Transfer Hydrogenation Using Biomass as Hydrogen Source
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We developed an operationally simple method for the direct use of biomass-derived chemical entities in a fundamentally important process, such as hydrogenation. Various carbohydrates, starch, and lignin were used for stereoselective hydrogenation. Employing a transition metal catalyst and a novel catalytic system, the reduction of alkynes, alkenes, and carbonyl groups with high yields was demonstrated. The regioselective hydrogenation to access different stereoisomers was established by simple variations in the reaction conditions. This work is based on an unprecedented catalytic system and represents a straightforward application of biomass as a reducing reagent in chemical reactions.
- Antonchick, Andrey P.,Manna, Srimanta
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p. 3094 - 3098
(2018/09/14)
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- A Novel Catalyst-Free Synthesis of 2,2-Diaryl Enamides from Stilbenes via a Nitrene Transfer Reaction
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A novel catalyst-free nitrene transfer reaction between stilbenes and iminoiodinanes was achieved for the first time, which provides an efficient and environmentally friendly way to access variously substituted 2,2-diaryl enamides under mild conditions. Mechanistic investigations suggested the reaction proceed via nitrene transfer and aromatic rearrangement with iminoiodinane also acting as a Lewis acid, benefitting the ring-opening of the aziridine intermediate.
- Zhang, Yuanyuan,Ye, Wenjing,Zhang, Hui,Xiao, Xiao
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supporting information
p. 5720 - 5724
(2019/08/26)
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- Selenolate Anion as an Organocatalyst: Reactions and Mechanistic Studies
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A new organocatalyst, the selenolate anion [RSe]–, generated from bench-stable and commercially available diphenyl diselenide or from phenyl benzyl selenide (10 mol%) is introduced. Benchmarking is performed in the conversion of benzylic chlorides into trans-stilbenes selectively at room temperature. Mechanistic studies support the intermediacy of the selenolate anion and of 1,2-diphenylethyl phenyl selenide. (Figure presented.).
- Trofymchuk, Oleksandra S.,Zheng, Zhipeng,Kurogi, Takashi,Mindiola, Daniel J.,Walsh, Patrick J.
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p. 1685 - 1692
(2018/03/21)
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- A new role for sulfenate anions: Organocatalysis
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(Chemical Equation Presented) The sulfenate anion is introduced for the first time as a catalyst and was found to facilitate the conversion of benzyl halides to trans-stilbenes. CPME=Cyclopentyl methyl ether.
- Schwan, Adrian L.
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p. 226 - 227
(2015/03/03)
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- Tert-butyl phenyl sulfoxide: A traceless sulfenate anion precatalyst
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tert-Butyl phenyl sulfoxide is employed as a traceless precatalyst for the generation of sulfenate anions under basic conditions and has been used to catalyze the coupling of benzyl halides to trans-stilbenes. The advantage of this precatalyst over previous precatalysts is that the byproduct generated on catalyst formation is a gas, facilitating product isolation in high purity. Using this second generation catalyst, a variety of trans-stilbenes were generated in 39-98% isolated yield.
- Zhang, Mengnan,Jia, Tiezheng,Sagamanova, Irina K.,Pericás, Miquel A.,Walsh, Patrick J.
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supporting information
p. 1164 - 1167
(2015/03/14)
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- A new class of organocatalysts: Sulfenate anions
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Sulfenate anions are known to act as highly reactive species in the organic arena. Now they premiere as organocatalysts. Proof of concept is offered by the sulfoxide/sulfenate-catalyzed (1-10 mol%) coupling of benzyl halides in the presence of base to generate trans-stilbenes in good to excellent yields (up to 99%). Mechanistic studies support the intermediacy of sulfenate anions, and the deprotonated sulfoxide was determined to be the resting state of the catalyst. Sulfenates take center stage: Sulfenate anions are known as highly reactive species in the organic arena. Now they premiere as organocatalysts: A sulfoxide/sulfenate (1-10 mol%) promotes the transformation of benzyl halides into trans-stilbenes under basic conditions (up to 99% yield). CPME=cyclopentyl methyl ether.
- Zhang, Mengnan,Jia, Tiezheng,Yin, Haolin,Carroll, Patrick J.,Schelter, Eric J.,Walsh, Patrick J.
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supporting information
p. 10755 - 10758
(2015/05/13)
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- Rhodium-catalyzed cross-coupling of alkenyl halides with arylboron compounds
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The rhodium(I)-catalyzed reaction between arylboronic esters and excess 1,2-dichloroethene selectively afforded (2-chlorovinyl)arenes. Double arylation yielding 1,2-diarylethenes was observed when 1,2-dibromoethene was reacted with 2.5 equivalents of aryl
- Matsuda, Takanori,Suzuki, Kentaro,Miura, Norio
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supporting information
p. 3396 - 3400
(2013/12/04)
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- Transition metal-free domino sequential synthesis of (E)-stilbenes, biaryl methanes and biaryl ethers using Et2AlCl as a Lewis acid
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A transition metal-free domino process has been developed, for the first time, to synthesize (E)-stilbenes, biaryl methanes and biaryl ethers from substituted α,β-unsaturated ketones, benzyl acetones and phenacyl ethers, respectively, in moderate to good yields at room temperature using diethyl aluminium chloride (Et2AlCl) as a Lewis acid. The Royal Society of Chemistry 2013.
- Sarkar, Satinath,Jana, Manoranjan,Tadigoppula, Narender
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p. 18755 - 18758
(2013/10/22)
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- Olefin cross-metathesis/Suzuki-Miyaura reactions on vinylphenylboronic acid pinacol esters
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A series of alkenyl phenylboronic acid pinacol esters has been synthesized via an olefin cross-metathesis reaction of vinylphenylboronic acid pinacol ester derivatives. After catalytic hydrogenation, the resulting boronates were coupled via a microwave-mediated Suzuki-Miyaura reaction to afford a library of biarylethyl aryl and biarylethyl cycloalkyl derivatives. A complementary reaction sequence involved an initial Suzuki-Miyaura coupling.
- Baltus, Christine B.,Chuckowree, Irina S.,Press, Neil J.,Day, Iain J.,Coles, Simon J.,Tizzard, Graham J.,Spencer, John
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supporting information
p. 1211 - 1217
(2013/03/13)
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- Synthesis of 2-bromo-1-aryl-1H-indenes via a Ag(I) promoted domino 2π-electrocyclic ring-opening/4π-electrocyclization reaction of 1,2-diaryl substituted gem-dibromocyclopropanes
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2-Bromo-1-aryl substituted indenes can be synthesized from 1,2-diaryl substituted gem-dibromocyclopropanes via a domino reaction sequence. The cascade reaction involves silver(I) promoted ionization and 2π-disrotatory electrocyclic ring-opening, followed by a 4π-conrotatory electrocyclic ring closing reaction of the allylic carbocation intermediate. Reaction conditions utilize silver tetrafluoroborate (AgBF4) in dichloroethane at 65 C. Selectivity effects for the electrocyclization were also studied. The 2-bromoindenes can be further functionalized using cross-coupling reactions, such as the Suzuki-Miyaura protocol. The alkene π-bond of the indenes can also be isomerized to give the thermodynamically more stable 2-bromo-3-aryl-1H-indene isomers using triethylamine in dichloromethane at room temperature.
- Rosocha, Gregory,Batey, Robert A.
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p. 8758 - 8768
(2013/09/23)
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- Sodium sulfinate-mediated trans-stilbene formation from benzylic halides
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A convenient and efficient method for the synthesis of various symmetrical and non-symmetrical trans-stilbene derivatives from benzylic halides in the absence of any transition metals is described. Sodium sulfinates played an important role in this transformation. Various functional groups were well tolerated under the optimized reaction conditions. Copyright
- Zhao, Feng,Luo, Jiaying,Tan, Qi,Liao, Yunfeng,Peng, Shengming,Deng, Guo-Jun
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supporting information; experimental part
p. 1914 - 1918
(2012/09/22)
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- Convenient and stereoselective synthesis of symmetrical (E)-stilbenes via homocoupling of 1,3-dibenzylbenzotriazolium bromides
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Using NaH as the base and DMSO as the solvent, a series of symmetric (E)-stilbenes were prepared in good yields via the -homocoupling of 1,3-dibenzylbenzotriazolium bromides at room temperature. Georg Thieme Verlag Stuttgart · New York.
- Xiao, Xiaohui,Lin, Daqin,Tong, Shuitian,Luo, Hong,He, Yinfeng,Mo, Hailan
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supporting information; experimental part
p. 1731 - 1734
(2011/09/16)
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- Biomimetic iron-catalyzed asymmetric epoxidation of aromatic alkenes by using hydrogen peroxide
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A novel and general biomimetic non-heme Fe-catalyzed asymmetric epoxidation of aromatic alkenes by using hydrogen peroxide is reported herein. The catalyst consists of ferric chloride hexahydrate (FeCl3·OH 2O), pyridine-2,6-dicarboxylic acid (H2-(pydic)), and readily accessible chiral N-arenesulfonyl-N′-benzyl-substituted ethylenediamine ligands. The asymmetric epoxidation of styrenes with this system gave high conversions but poor enantiomeric excesses (ee), whereas larger alkenes gave high conversions and ee values. For the epoxidation of trans-stilbene (1a), the ligands (S,S)-N-(4-toluenesulfonyl)-1,2- diphenylethylenediamine ((S,S)-4a) and its N′-benzylated derivative ((S,S)-5a) gave opposite enantiomers of trans-stilbene oxide, that is, (S,S)-2a and (R,R)-2a, respectively. The enantioselectivity of alkene epoxidation is controlled by steric and electronic factors, although steric effects are more dominant. Preliminary mechanistic studies suggest the in situ formation of several chiral Fe-complexes, such as [FeCl(L*)2-(pydic)] ·HCl (L* = (S,S)-4a or (S,S)-5a in the catalyst mixture), which were identified by ESIMS. A UV/Vis study of the catalyst mixture, which consisted of FeCl3·6H2O, H2(pydic), and (S,S)-4a, suggested the formation of a new species with an absorbance peak at λ = 465 nm upon treatment with hydrogen peroxide. With the aid of two independent spin traps, we could confirm by EPR spectroscopy that the reaction proceeds via radical intermediates. Kinetic studies with deuterated styrenes showed inverse secondary kinetic isotope effects, with values of k H/kD = 0.93 for the β carbon and kH/k D=0.97 for the a carbon, which suggested an unsymmetrical transition state with stepwise O transfer. Competitive epoxidation of para-substituted styrenes revealed a linear dual-parameter Hammett plot with a slope of 1.00. Under standard conditions, epoxidation of la in the presence of ten equivalents of H218O resulted in an absence of the isotopic label in (S,S)-2a. A positive non-linear effect was observed during the epoxidation of la in the presence of (S,S)-5a and (R,R)-5a.
- Gelalcha, Feyissa Gadissa,Anilkumar, Gopinathan,Tse, Man Kin,Brueckner, Angelika,Beller, Matthias
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experimental part
p. 7687 - 7698
(2009/08/07)
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- Enantioselective ring-opening reaction of meso-epoxides with ArSH catalyzed by a C2-symmetric chiral bipyridyldiol-titanium complex
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This study describes a C2-symmetric ligand comprising a central bipyridine-pinene-derived core and two functionalized diphenylmethanol subunits. [8′-(Hydroxy-diphenyl-methyl)-10,10,10′,10′-tetramethy l-[5,5′]bi[6-aza-tricyclo[7.1.1.02,7/s
- Chen, Yi-Jing,Chen, Chinpiao
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p. 1313 - 1319
(2008/02/09)
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- LAH induced stereoselective dehalogenation of vicinal-dihalides via single electron transfer
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Vicinal-dihalides have been observed to undergo dehalogenation to alkenes with LAH under nitrogen atmosphere. The elimination is stereoselective and no reduced products are formed. The possibility of LAH acting as a hydride transfer reagent or as a base has been eliminated and a SET mechanism has been proposed for these reactions.
- Khurana, Jitender M.,Puri, Amita
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p. 910 - 913
(2007/10/03)
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- Mechanistic criteria for cation radical reactions: Aminium salt-catalyzed cyclopropanation
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Mechanistic studies of the cyclopropanation of a series of trans-stilbenes by ethyl diazoacetate catalyzed by two different triarylaminium salts decisively confirm a cation radical mechanism and rule out a hypothetical electrophilic mechanism. The elucidation of key aspects of these cation radical mechanisms, including kinetic vs equilibrium control of ionization and chain vs catalytic mechanisms, has also been achieved for these systems. New mechanistic criteria for the positive identification of cation radical mechanisms are proposed.
- Yueh, Wang,Bauld, Nathan L.
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p. 5671 - 5676
(2007/10/02)
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- Tandem carbonyl coupling-rearrangements promoted by the niobium(III) reagent. Dual reductive and Lewis acid properties of NbCl3(DME)
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Benzaldehyde (1a) and acetophenone (6) are shown to undergo highly stereoselective reductive couplings by NbCl3(DME). When the reaction is performed at -10°C, the threo diols can be isolated. The intermediate niobiopinacols reveal the ability of subsequent transformations, due to the Lewis acid properties of the reagent used. Starting from 1a stereospecific acetalization leads to threo-2,4,5-triphenyl-1,3-dioxolane (3a), whereas 3,3-diphenyl-2-butanone (7) is obtained from 6 in a pinacol-pinacolone type rearrangement. Alkenes may also be formed in the competing, temperature controlled deoxygenation. The stereoselectivity and the easy control of NbCl3(DME) mediated reactions make it a promising reagent for further synthetic applications.
- Szymoniak,Besancon,Moise
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p. 3867 - 3876
(2007/10/02)
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- REDUCTIVE COUPLING OF BENZOIC ACID HALIDES AND ESTERS USING LOW-VALENT TITANIUM
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The reductive coupling of (substituted) benzoic acid chlorides and esters is achieved using low-valent titanium, generated from TiCl3 and LiAlH4.Both acid chlorides and esters seem to follow the same two reaction pathways: one path via tolanes to stilbenes, the other via benzils to complex mixtures of products arising from reduction and further coupling reactions.Although the exact product balance depends upon the reaction conditions the major product is (substituted) cis-stilbene.
- Dang, Y.,Geise, H. J.
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p. 375 - 380
(2007/10/02)
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- Ultrasound-Mediated Synthesis and Mass Spectrometric Fragmentation of Dimethyl-Substituted 1,2-Diphenylethanols, Convenient Dimethylstilbene Precursors
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1,2-Diarylethanols were obtained in high yields by ultrasonic irradiation of mixtures of lithium sand, benzylic chlorides, and arenecarbaldehydes or aryl methyl ketones.The mass spectra of the alcohols contained dominant peaks for species formed by dehydration, α-cleavage processes and rearrangement involving hydrogen transfer.Acid-catalyzed dehydration of the alcohols gave the corresponding stilbenes in quantitative yields.
- Burkow, Ivan C.,Sydnes, Leiv K.,Ubeda, Danielle C. N.
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p. 235 - 244
(2007/10/02)
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- ZEOLITE-CuNaY CATALYZED DECOMPOSITION OF ARYLDIAZOMETHANE
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Decomposition of aryldiazomethanes is catalyzed by copper ion-exchanged Y-type zeolite to afford cis-1,2-diarylethylenes in high selectivity.The catalytic activity and selectivity are found to be affected by the exchange level of copper ions in zeolite and the solvent used.
- Onaka, Makoto,Kita, Hiroshi,Izumi, Yusuke
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p. 1895 - 1898
(2007/10/02)
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- REACTION OF ARYLMETHANESULFONYL AND STYRYLMETHANESULFONYL CHLORIDES WITH TRIETHYLAMINE
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A series of arylmethanesulfonyl chlorides were treated with triethylamine in THF to give stilbenes in excellent yields.Workup of the mixtures below 10 deg C permits isolation of stilbene episulfones which on warming decompose to yield the corresponding stilbenes stereospecifically.Application of the reaction to 9-fluorenylsulfonyl chloride affords bifluorenylidene, while trans-styrylmethanesulfonyl chloride gives 4,5-dihydro-4,5-diphenylthiepin 1,1-dioxide and 1,6-diphenylhexatriene.
- Nakayama, Juzo,Tanuma, Mitsuru,Honda, Yoshiko,Hoshino, Masamatsu
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p. 4553 - 4556
(2007/10/02)
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- Chemistry of Heterocyclic Compounds. 55. Synthesis and Conformational Studies of Substituted 1,2-Diaryl- and Heteroarylbenzenes. Synthesis of Benzopyridinocyclophanes
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The syntheses of 1,2-bis(3-methylphenyl)-, 1-(6-methyl-2-pyridyl)-2-(3-methylphenyl)-, and 1,2-bis(6-methyl-2-pyridyl)benzenes are described.The aryl and heteroaryl olefins were brominated and didehydrobrominated to give the corresponding acetylenes, whic
- Newkome, George R.,Roper, Jerry M.,Robinson, Michael J.
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p. 4380 - 4385
(2007/10/02)
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