- A SIMPLE SYNTHESIS OF TRANS, TRANS-1,3-DIENES FROM TERMINAL ALKYNES USING CoCl2/Ph3P/NaBH4
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The cobalt hydride reagent prepared in situ in THF at -20 deg C using CoCl2/NaBH4/Ph3P in the 1:1:4 ratio hydrodimerizes terminal alkynes into the corresponding trans, trans-1,3-dienes in good yields (65 to 86percent).
- Satyanarayana, N.,Periasamy, M.
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- A novel stereoselective synthesis of symmetrical (1E,3E)-1,4-diarylbuta-1, 3-dienes
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A convenient methodology for the stereoselective synthesis of symmetrical (1E,3E)-1,4-diarylbuta-1,3-dienes based on palladium-catalyzed Suzuki-Miyaura cross-coupling reaction of (1E,3E)-1,4-diiodobuta-1,3-diene with arylboronic reagents is reported. Georg Thieme Verlag Stuttgart.
- Babudri, Francesco,Farinola, Gianluca M.,Naso, Francesco,Ragni, Roberta,Spina, Giulia
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- Mechanism of a Suzuki-Type Homocoupling Reaction Catalyzed by Palladium Nanocubes
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The trans-2-phenylvinylboronic acid homocoupling reaction catalyzed by palladium nanocubes (Pd-NCs) was investigated by kinetics, spectroscopy, and poisoning experiments. The reaction was evidenced to be sensitive to the presence of the base, which acts synergistically with the substrate molecules and assists the leaching of Pd oxide (PdOx) species to the reaction medium. This species catalyzes the homocoupling reaction through the formation of Pd-Ox-B(OH)2R pretransmetalation intermediates, via coordination with the vinylboronic acid molecules, involving an oxo-palladium-type interaction. The reaction rate was not enhanced by the saturation of the reaction medium with O2, which is due to the oxidized nature of the Pd-NC surface.
- Elias, Welman C.,Signori, Aline M.,Zaramello, Laize,Albuquerque, Brunno L.,De Oliveira, Daniela C.,Domingos, Josiel B.
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- Efficient Conditions for the Palladium(II) Mediated Coupling of Organostannanes: The Synthesis of 1,3-Dienes, 1,4-Dienes, 1,3-Diynes and Biphenyls
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Convenient conditions are described for the preparation of 1,3-dienes by vinylstannane homocoupling using palladium(II)-catalysis with oxygen (or air) for Pd(0)/Pd(II) reoxidation; related homo-couplings, and cross-coupling reactions with allylstannane, are used to obtain 1,3-diynes, biaryls and 1,4-dienes.
- Alcaraz, Lilian,Taylor, Richard J. K.
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- Stereoselective synthesis of (Z,E)-2-phenylselenobutadienes by palladium-catalyzed cross-coupling reaction
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Hydrozirconation of 1-alkynes gives ( E )-alkenylzirconium complexes 3, which are cross-coupled with (E)-α-phenylselenovinyl bromides (4) in the presence of tetrakis (triphenylphosphine) palladium catalyst to afford (Z,E )-2-phenylselenobutadienes (5) in good yields.
- Cai, Ming-Zhong,Huang, Jia-Di,Peng, Chun-Yun
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- Photoisomerization of cis,cis-1,4-diphenyl-1,3-butadiene in glassy media at 77 K: The bicycle-pedal mechanism
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The cis-trans photoisomerization of cis,cis-1,4-diphenyl-1,3-butadiene in a soft isopentane glass at 77 K gives significant two-bond photoisomerization in contrast to solution and hard glassy media where only one-bond photoisomerization takes place. The Royal Society of Chemistry 2006.
- Saltiel, Jack,Krishna, Tallapragada S. R.,Turek, Andrzej M.,Clark, Ronald J.
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- Hydrocupration of Alkynes: a Simple Synthesis of (E,E)-1,3-Dienes
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Copper(I) hydride species, prepared in situ in tetrahydrofuran using NaBH4-MgBr2-Et3N-CuCl or NaH-MgBr2-CuCl reagent systems, convert terminal alkynes into (E,E)-1,3-dienes in good yields.
- Rao, S. Achyutha,Periasamy, Mariappan
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- Mechanisms of photoisomerization of polyenes in confined media: From organic glasses to protein binding cavities
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Photochemical reactivities of model organic systems (stilbene and diphenylbutadiene) in organic glasses were first examined and compared with those in solution and in organized media. These observations were in turn compared with reactivities of polyene chromophores in protein binding cavities (specifically PYP, rhodopsin and bacteriorhodopsin). The obvious conclusion is that the preference for the most volume-conserving Hula-twist mechanism isomerization in organic glasses is because of the close interaction between the guest and the host molecules. In organized media (zeolites, crystals and protein binding cavities), the residual empty space coupled with any specific guest-host interactions that are characteristic of a given system, could lead to involvement of the more volume-demanding one-bond-flip (i.e. torsional relaxation) or bicycle-pedal or an extended HT process in photoisomerization.
- Liu, Robert S. H.,Yang, Lan-Ying,Liu, Jin
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- New aspects of diphenylbutadiene photochemistry. Regiospecific Hula-twist photoisomerization
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In EPA glass at liquid nitrogen temperature, the E,E isomer of diphenylbutadiene (DPB) was photostable, while both the Z,E and Z,Z isomers underwent selective HT isomerization at center 1 giving the stable conformer of the double-bond isomerized trans product. That HT-1 was involved rather than the OBF process was shown by results of o,o-dimethyl-DPB. Formation of unstable trans product corresponded to simultaneous configurational and conformational isomerization. The regioselectivity was found not sensitive to a substituent effect, as shown by the similar reactivity in p,p- or o,o-bistrifluoromethyl-DPB. Copyright
- Yang, Lan-Ying,Liu, Robert S. H.,Boarman, Kelly J.,Wendt, Natalie L.,Liu, Jin
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- Direct and Sensitized Photoisomerization of 1,4-Diphenylbutadienes
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Photoisomerization of the three stereoisomers of 1,4-diphenylbutadiene (DPB) in room-temperature cyclohexane solution was studied by direct excitation and by triplet sensitization.The photostationary mixtures in both singlet and triplet experiments contain only trans,trans and cis,trans isomers; no cis,cis isomer or any photoproducts were observed.The two cis isomers exhibit no measureable fluorescence or triplet formation. results are interpreted in terms of allylmethylene-like intermediates.Efficient internal conversion of singlet DPBs is inferred from low isomerization quantum yields by direct excitation.Triplet-sensitized isomerizations show a marked DPB concentration dependence of photostationary compositions and quantum yields.Analysis of these data reveals a quantum chain process involving excited triplet DPB as the chain-carrying species.Transient absorption measurements show that sensitized excitation of any DPB isomer leads directly to a fast equilibrium between triplet all-trans and trans-twisted forms.
- Yee, W. Atom,Hug, Stephan J.,Kliger, David S.
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- Design of Hemilabile N,N,N-Ligands in Copper-Catalyzed Enantioconvergent Radical Cross-Coupling of Benzyl/Propargyl Halides with Alkenylboronate Esters
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The enantioconvergent radical C(sp3)-C(sp2) cross-coupling of alkyl halides with alkenylboronate esters is an appealing tool in the assembly of synthetically valuable enantioenriched alkenes owing to the ready availability, low toxicity, and air/moisture stability of alkenylboronate esters. Here, we report a copper/chiral N,N,N-ligand catalytic system for the enantioconvergent cross-coupling of benzyl/propargyl halides with alkenylboronate esters (>80 examples) with good functional group tolerance. The key to the success is the rational design of hemilabile N,N,N-ligands by mounting steric hindrance at the ortho position of one coordinating quinoline ring. Thus, the newly designed ligand could not only promote the radical cross-coupling process in the tridentate form but also deliver enantiocontrol over highly reactive alkyl radicals in the bidentate form. Facile follow-up transformations highlight its potential utility in the synthesis of various enantioenriched building blocks as well as in the late-stage functionalization for drug discovery.
- Wang, Peng-Fei,Yu, Jiao,Guo, Kai-Xin,Jiang, Sheng-Peng,Chen, Ji-Jun,Gu, Qiang-Shuai,Liu, Ji-Ren,Hong, Xin,Li, Zhong-Liang,Liu, Xin-Yuan
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p. 6442 - 6452
(2022/04/19)
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- Cobalt-Catalyzed Z to e Geometrical Isomerization of 1,3-Dienes
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An efficient cobalt-catalyzed geometrical isomerization of 1,3-dienes is described. In the combination of a CoCl2 precatalyst with an amido-diphosphine-oxazoline ligand, the geometrical isomerization of E/Z mixtures of 1,3-dienes proceed in a stereoconvergent manner, affording (E) isomers in high stereoselectivity. This facile transformation features a broad substrate scope with good functional group tolerance and could be scaled up to the gram scale smoothly with a catalyst loading of 1 mol %.
- Wang, Wei,He, Shuying,Zhong, Yuqing,Chen, Jianhui,Cai, Cheng,Luo, Yanshu,Xia, Yuanzhi
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- Custom-Made Pyrene Photocatalyst-Promoted Desulfonylation of Arylethenyl Sulfones Using Green-Light-Emitting Diodes
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The Sonogashira coupling of 1,3,6,8-tetrabromopyrene with 4-[(-)-β-citronellyloxy]phenylethyne was employed to synthesize 1,3,6,8-tetra[4-(citronellyloxy)phenylethynyl]pyrene. The pyrene derivative catalyzed the reductive desulfonylation of ethenyl sulfones via visible-light irradiation (514 nm green light-emitting diodes) in the presence of i -Pr 2NEt. The β-citronellyloxy groups provided the sufficient solubility to the highly π-expanded pyrene catalyst, and their polar oxygen functionalities enabled the easy separation of the catalyst from the products via column chromatography.
- Watanabe, Hikaru,Nakajima, Kazuki,Ekuni, Kento,Edagawa, Ryota,Akagi, Yuta,Okuda, Yasuhiro,Wakamatsu, Kan,Orita, Akihiro
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p. 2984 - 2994
(2021/03/04)
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- A Solid-Phase Assisted Flow Approach to In Situ Wittig-Type Olefination Coupling
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Described herein is the development of a continuous flow, solid-phase triphenylphosphine (PS-PPh3) assisted protocol to facilitate the in situ coupling of reciprocal pairs of halogen and carbonyl functionalised molecular pairs by a Wittig olefination within 15 mins. The protocol entails injecting a single solution (1 : 1 CHCl3 : EtOH) containing the halogenated and carbonyl-based substrates into a continuously flowing stream of CHCl3 : EtOH (1 : 1), passed through a fixed bed of K2CO3 and PS-PPh3. With advancement to the previous PS-PPh3 coupling procedures, the method employs a traditional polystyrene-based immobilisation matrix, the substrate scope of the protocol extended to substituted ketones, secondary alkyl chlorides, and an unprotected maleimide scaffold.
- Aldrich-Wright, Janice R.,Dankers, Christian,Gordon, Christopher P.,Polyzos, Anastasios,Tadros, Joseph
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supporting information
p. 4184 - 4194
(2021/08/24)
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- Ruthenium-catalysed oxidative coupling of vinyl derivatives and application in tandem hydrogenation
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The first ruthenium-catalyzed oxidative homo- and cross-coupling of exclusive vinyl derivatives giving highly valued 1,3-diene building blocks is reported. The catalytic system is based on readily available reagents and it mainly delivers the E,E isomer. This methodology also enables the synthesis of adipic acid ester derivatives in a one-pot fashion after in situ ruthenium-catalyzed hydrogenation.
- Abuhafez, Naba,Bruneau, Christian,Gramage-Doria, Rafael,Kamaraj, Raghu,Ruffin, Hervé
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p. 5772 - 5776
(2021/09/10)
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- [Rh(Cod)Cl]2/Pph3?catalyzed dehydrogenative silylation of styrene derivatives with NBE as a hydrogen acceptor
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Direct synthesis of arylalkenylsilanes by [Rh(COD)Cl]2/ PPh3-catalyzed dehydrogenative silylation of styrene derivatives with R3SiH (R = alkyl, alkoxy, aryl) was realized, in which norbornene (NBE) and PPh3 play a key role in achieving excellent selectivity in the formation of dehydrogenative silylation products. Moreover, this high-yielding transformation exhibits a broad substrate scope and good functional group tolerance.
- Li, Chengyang,Lu, Wenkui,Wu, Xiaoyu,Xie, Xiaomin,Zhang, Zhaoguo
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p. 3780 - 3788
(2020/11/23)
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- The photoisomerization of: Cis, trans -1,2-dideuterio-1,4-diphenyl-1,3-butadiene in solution. No bicycle-pedal
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cis,trans-1,2-Dideuterio-1,4-diphenyl-1,3-butadiene (ct-DPBd2) was synthesized and its cis-trans photoisomerization in cyclohexane-d12 (C6D12) at room temperature was monitored by 1H NMR spectroscopy. The results reveal formation of only trans,trans-1,2-dideuterio-1,4-diphenyl-1,3-butadiene (tt-DPBd2). The failure to detect formation of trans,cis-1,2-dideuterio-1,4-diphenyl-1,3-butadiene (tc-DPBd2) eliminates the possibility that an identity bicycle pedal process contributes to inefficiency in the cis-trans photoisomerization of cis,trans-1,4-diphenyl-1,3-butadiene (ct-DPB).
- Saltiel, Jack,Redwood, Christopher E.,Ratheesh Kumar
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p. 2174 - 2179
(2019/09/18)
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- Fluoroalkenylation of boronic acids: Via an oxidative Heck reaction
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A fluoroalkenylation of boronic acids with fluoroalkyl alkenes has been developed. The Pd-catalyzed oxidative Heck coupling reaction proceeds under an oxygen atmosphere at room temperature, in the absence of a base and/or a ligand, showing excellent practicality of the process. This simple transformation is highly stereoselective to provide only E-isomers. In addition to the general approach using alkenes with functionalized fluoroalkyl reagents, this method, by transferring an aromatic system to the electron-deficient fluoroalkyl alkene, provides an efficient alternative method to yield valuable organofluorines.
- Lee, Da Seul,Cho, Eun Jin
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p. 4317 - 4325
(2019/05/06)
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- H2-Acceptorless Dehydrogenative Boration and Transfer Boration of Alkenes Enabled by Zirconium Catalyst
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The first example of an efficient and direct dehydrogenative boration of alkenes for vinyl boronate ester synthesis was achieved using a zirconium catalyst. Our methodology avoids using precious transition metals, additional hydrogen acceptors, high temperatures, and long reaction times, which were required to overcome the reducing ability of borane, to give alkyl boronate esters. Detailed mechanistic studies revealed a reversible reaction pathway and further suggested applying the zirconium complex as a “shuttle catalyst” for transfer boration, which thus sidesteps the use of relatively sensitive borane.
- Shi, Xiaonan,Li, Sida,Wu, Lipeng
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p. 16167 - 16171
(2019/11/03)
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- AgSbF6-Catalyzed: Anti -Markovnikov hydroboration of terminal alkynes
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AgSbF6-Catalyzed anti-Markovnikov addition of pinacolborane (HBpin) to terminal alkynes to produce the E-vinylboronates is reported. This efficient methodology is scalable, compatible with sterically and electronically diverse alkynes, and works at room temperature under solvent-free condition. The utility of this method is demonstrated in the facile synthesis of the clinically important (E)-2,4,3′,5′-tetramethoxystilbene.
- Mamidala, Ramesh,Pandey, Vipin K.,Rit, Arnab
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p. 989 - 992
(2019/01/23)
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- Iron(III)/O2-Mediated Regioselective Oxidative Cleavage of 1-Arylbutadienes to Cinnamaldehydes
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A simple, efficient, and environmentally benevolent regioselective oxidative cleavage of 1-arylbutadienes to cinnamaldehydes mediated by iron(III) sulfate/O2 has been developed. The reaction offered good yields and excellent regioselectivity and showed good functional group tolerance (31 examples). The method is important, as few reports with limited substrate scope are available for such excellent oxidative cleavage of conjugated dienes.
- Bhowmik, Amit,Fernandes, Rodney A.
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supporting information
p. 9203 - 9207
(2019/11/14)
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- A POCO type pincer complex of iridium: Synthesis, characterization, and catalysis
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A convenient synthesis of a new POCO-type pincer ligand, “tBuPOCOH” (3-(di-tert-butylphosphinito)acetophenone is reported. Metallation using [Ir(COD)Cl]2 provides the dimeric species (μ-Cl-[tBuPOCOIrHCl]2) (1a) as a major product, along with isomer 1b. Though not fully characterized, 1b is shown to be chemically equivalent to 1a by a series of experiments with AgOTf and CO which lead to formation of a single product, tBuPOCOIr(CO)HOTf (3). The 1a/b mixture gives inferior results to iPrPCPIr when used as pre-catalyst in the dehydrogenative coupling of vinyl arenes, though olefin isomerization activity is enhanced. This system was also evaluated in the Geurbet conversion of ethanol to n-butanol and higher alcohols. The CO adducts of 1a/b, cis/trans-2, were found to give the best results as pre-catalyst, achieving a 33% yield of n-butanol and an overall 47% yield of n-alcohols with a catalyst loading of 0.5% when heated at 150 °C for 4 hours. This represents the first example of a pincer ligated iridium complex as catalyst in the Geurbet reaction of ethanol.
- Wilklow-Marnell, Miles,Brennessel, William W.
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- Ligand-Free Iron-Catalyzed Carbon (sp2)-Carbon (sp2) Oxidative Homo-Coupling of Alkenyllithiums
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A new strategy was developed for the efficient synthesis of di-, tetra-, and hexa-substituted 1,3-butadienes. This one-pot procedure involves lithium-iodine exchange to generate the corresponding vinyllithium intermediates. A subsequent iron-catalyzed ligand-free oxidative homo-coupling eventually led to the formation of 1,3-butadienes in acceptable to excellent isolated yields.
- Zhong, Zhuliang,Wang, Zhi-Yong,Ni, Shao-Fei,Dang, Li,Lee, Hung Kay,Peng, Xiao-Shui,Wong, Henry N. C.
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supporting information
p. 700 - 704
(2019/02/07)
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- Efficient Homocoupling of Aryl- and Alkenylboronic Acids in the Presence of Low Loadings of [{Pd(μ-OH)Cl(IPr)} 2 ]
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NHC-palladium(II) complex [{Pd(μ-OH)Cl(IPr)} 2 ] (IPr = bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) catalyzes the oxidative coupling of a broad spectrum of aryl- and alkenylboronic acids at loadings down to 5 ppm. At the concentration of 0.05 mol% the catalyst permits an efficient reaction under base-free conditions.
- Ostrowska, Sylwia,Rogalski, Szymon,Lorkowski, Jan,Walkowiak, Jedrzej,Pietraszuk, Cezary
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supporting information
p. 1735 - 1740
(2018/07/21)
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- Pd-catalyzed oxidative homo-coupling of acrylates and aromatic alkenes for the conjugated diene synthesis
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We developed a bidentate monoanionic nitrogen ligand that was effective in the Pd-catalyzed oxidative homo-coupling reaction of acrylates and aromatic alkenes. In the presence of Pd(OAc)2/ligand several conjugated dienes were obtained in good yields with high stereoselectivities.
- Zhu, Ting,Li, Zhen,Xiao, Fanhua,Duan, Wei-Liang
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supporting information
p. 3238 - 3241
(2018/07/21)
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- Nickel-Catalyzed system for the cross-coupling of alkenyl methyl ethers with grignard reagents under mild conditions
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A nickel-catalyzed cross-coupling of alkenyl methyl ethers with Grignard reagents, under mild conditions, is described. These conditions allowed access to various stilbenes and heterocyclic stilbenic derivatives as well as to a potential anticancer agent DMU-212.
- Hostier, Thomas,Neouchy, Zeina,Ferey, Vincent,Gomez Pardo, Domingo,Cossy, Janine
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p. 1815 - 1818
(2018/04/14)
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- A Copper-Catalyzed Reductive Defluorination of β-Trifluoromethylated Enones via Oxidative Homocoupling of Grignard Reagents
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An efficient copper-catalyzed reductive defluorination of β-trifluoromethylated enones via an oxidative homocoupling of Grignard reagents is reported. The reaction proceeded smoothly with a wide range of substrates, including the ones bearing aromatic heterocycles, such as furyl and thienyl ring systems in high yields (80-92%, except one example) under mild conditions. This provides a practical method for synthesis of gem-difluoroolefin ketones. It is also worth noting that this homocoupling process of Grignard reagents using β-trifluoromethylated enones as oxidizing reagents is effective for both the Csp2-Csp2 and Csp3-Csp3 bond formations, including for substrates whose β-hydride elimination of the corresponding transition metal alkyl complex is particularly facile, affording coupling products with high yields (83-95%), simultaneously.
- Wu, Xiaoting,Xie, Fang,Gridnev, Ilya D.,Zhang, Wanbin
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supporting information
p. 1638 - 1642
(2018/03/23)
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- M -C2B10H11HgCl/AgOTf-Catalyzed Reaction for Reductive Deoxygenation
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A m -C2B10H11HgCl/AgOTf-catalyzed reaction of allyl silyl ethers with N -Boc- N ′-tosylhydrazine has been developed. Under mild conditions, the resulting allyl hydrazine products were transformed into naked alkenes in good yield. Furthermore, the used m -C2B10H11HgCl could be recovered quantitatively.
- Yamasaki, Naoto,Kanno, Marina,Sakamoto, Kyohei,Kasai, Yusuke,Imagawa, Hiroshi,Yamamoto, Hirofumi
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supporting information
p. 169 - 175
(2018/03/26)
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- Transition-Metal-Free Sulfuration/Annulation of Alkenes: Economical Access to Thiophenes Enabled by the Cleavage of Multiple C-H Bonds
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A novel, atom economical, and transition-metal-free strategy for the synthesis of thiophenes from substituted buta-1-enes with potassium sulfide has been presented. The reaction achieves double C-S bond formations via cleavage of multiple C-H bonds and provides an efficient approach to access various functionalized thiophenes. Moreover, the strategy can also be used for the synthesis of thiophenes from 1,4-diaryl-1,3-dienes. Mechanistically, DMSO plays a role of oxidant and S3?- in situ generated from K2S is involved.
- Chen, Liang,Min, Hao,Zeng, Weilan,Zhu, Xiaoming,Liang, Yun,Deng, Guobo,Yang, Yuan
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supporting information
p. 7392 - 7395
(2019/01/03)
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- Can the Ti(OiPr)4/nBuLi combination of reagents function as a catalyst for [2+2+2] alkyne cyclotrimerisation reactions?
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Catalysis of the cyclotrimerisation of alkynes with the Ti(OiPr)4/nBuLi system was studied, leading to the development of a particularly convenient and reliable protocol. This method allows the [2+2+2] cycloaddition reaction to proceed within a few minutes under microwave conditions, with generally good selectivity from a variety of aromatic and aliphatic alkynes.
- Siemiaszko, Gabriela,Six, Yvan
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supporting information
p. 20219 - 20226
(2018/12/13)
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- O -Iodoxybenzoic acid mediated generation of aryl free radicals: Synthesis of stilbenes through C-C cross-coupling with β-nitrostyrenes
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The generation of an aryl free radicals in the presence of nitrostyrenes through a combination of aryl hydrazines and o-iodoxybenzoic acid led to the synthesis of stilbenes by forming a new carbon-carbon bond after subsequent elimination of a nitrosyl radical. The symmetrical and unsymmetrical stilbenes with excellent E-selectivity were synthesized in good yields, with advantages of broad substrate scope and transition metal free, mild reaction conditions, under an open atmosphere in a short reaction time. A free radical mediated mechanism was postulated and supported by radical trapping experiments. Application of the developed methodology is demonstrated through a simple, two step synthesis of resveratrol, a valuable stilbenoid for anticancer and neurological studies via its prodrug E-1,3-dimethoxy-5-(4-methoxystyryl)benzene.
- Wagh, Ganesh,Autade, Snehalata,Patil, Pravin C.,Akamanchi, Krishnacharya G.
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p. 3301 - 3309
(2018/03/06)
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- Catalytic Dehydrogenative C-C Coupling by a Pincer-Ligated Iridium Complex
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The pincer-iridium fragment (iPrPCP)Ir (RPCP = ?3-2,6-C6H3(CH2PR2)2) has been found to catalyze the dehydrogenative coupling of vinyl arenes to afford predominantly (E,E)-1,4-diaryl-1,3-butadienes. The eliminated hydrogen can undergo addition to another molecule of vinyl arene, resulting in an overall disproportionation reaction with 1 equiv of ethyl arene formed for each equivalent of diarylbutadiene produced. Alternatively, sacrificial hydrogen acceptors (e.g., tert-butylethylene) can be added to the solution for this purpose. Diarylbutadienes are isolated in moderate to good yields, up to ca. 90% based on the disproportionation reaction. The results of DFT calculations and experiments with substituted styrenes indicate that the coupling proceeds via double C-H addition of a styrene molecule, at β-vinyl and ortho-aryl positions, to give an iridium(III) metalloindene intermediate; this intermediate then adds a β-vinyl C-H bond of a second styrene molecule before reductively eliminating product. Several metalloindene complexes have been isolated and crystallographically characterized. In accord with the proposed mechanism, substitution at the ortho-aryl positions of the styrene precludes dehydrogenative homocoupling. In the case of 2,4,6-trimethylstyrene, dehydrogenative coupling of β-vinyl and ortho-methyl C-H bonds affords dimethylindene, demonstrating that the dehydrogenative coupling is not limited to C(sp2)-H bonds.
- Wilklow-Marnell, Miles,Li, Bo,Zhou, Tian,Krogh-Jespersen, Karsten,Brennessel, William W.,Emge, Thomas J.,Goldman, Alan S.,Jones, William D.
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supporting information
p. 8977 - 8989
(2017/07/12)
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- Reductive Homocoupling of Organohalides Using Nickel(II) Chloride and Samarium Metal
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A homocoupling method for organohalides and organosulfonates promoted by samarium metal and HMPA, and catalyzed by NiCl2 has been developed. Various organohalides (benzyl, aryl, heterocyclic, alkenyl and alkyl halides), α-haloacetophenones, and phenyl organosulfonates were tolerated, and the reaction afforded coupling products with high efficiency. Excellent chemoselectivity was exhibited between halides and other groups, such as ?COOH, ?NO2, halogen, heterocyclic ring, ester, and ketone groups. The stereoselectivity suggested that the reaction mechanism might involve an organosamarium species.
- Liu, Yongjun,Xiao, Shuhuan,Qi, Yan,Du, Feng
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p. 673 - 678
(2017/03/22)
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- Copper(I)-catalyzed stereoselective hydrogenation of 1,3-diynes and enynes
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A stereoselective hydrogenation of 1,3-diynes with an air-stable copper(I)/N-heterocyclic carbene complex, [IPrCuOH], has been developed. The corresponding products, 1,3-dienes, are obtained in a stereoselective manner depending on their substitution pattern: Diaryl-diynes yield E,E-1,3-dienes, whereas dialkyl-diynes are converted to the corresponding Z,Z-1,3-dienes. Hydrogenation and deuteration experiments with enynes indicate that these are competent reaction intermediates in the hydrogenation of diynes.
- Thiel, Niklas O.,Kemper, Sebastian,Teichert, Johannes F.
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p. 5023 - 5028
(2017/07/27)
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- Carbon-carbon bond forming reactions via Pd-catalyzed detellurative homocoupling of diorganyl tellurides
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A simple and highly efficient method for the constructions of Csp-Csp, Csp2-Csp2 and Csp3-Csp3 bonds is reported. The symmetrical diaryl tellurides undergo detellurative homocouplings to afford symmetrical biaryl products. The reactions are carried out at ambient temperature using PdCl2 as a catalyst in the presence of Ag2O and Na2CO3. Similarly, the detellurative homocouplings of dibenzyl telluride and bis(phenylethynyl)telluride give bibenzyl and the conjugated diyne, respectively.
- Zhang, Shaozhong,Kolluru, Lalitha,Vedula, Souseelya K.,Whippie, Drew,Jin, Jin
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supporting information
p. 3594 - 3597
(2017/08/23)
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- Cyclobutene vs 1,3-Diene Formation in the Gold-Catalyzed Reaction of Alkynes with Alkenes: The Complete Mechanistic Picture
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The intermolecular gold(I)-catalyzed reaction between arylalkynes and alkenes leads to cyclobutenes by a [2 + 2] cycloaddition, which takes place stepwise, first by formation of cyclopropyl gold(I) carbenes, followed by a ring expansion. However, 1,3-butadienes are also formed in the case of ortho-substituted arylalkynes by a metathesis-type process. The corresponding reaction of alkenes with aryl-1,3-butadiynes, ethynylogous to arylalkynes, leads exclusively to cyclobutenes. A comprehensive mechanism for the gold(I)-catalyzed reaction of alkynes with alkenes is proposed on the basis of density functional theory calculations, which shows that the two pathways leading to cyclobutenes or dienes are very close in energy. The key intermediates are cyclopropyl gold(I) carbenes, which have been independently generated by retro-Buchner reaction from stereodefined 1a,7b-dihydro-1H-cyclopropa[a]naphthalenes.
- De Orbe, M. Elena,Amenós, Laura,Kirillova, Mariia S.,Wang, Yahui,López-Carrillo, Verónica,Maseras, Feliu,Echavarren, Antonio M.
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p. 10302 - 10311
(2017/08/09)
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- Metathesis of renewable polyene feedstocks – Indirect evidences of the formation of catalytically active ruthenium allylidene species
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Cross-metathesis (CM) of conjugated polyenes, such as 1,6-diphenyl-1,3,5-hexatriene (1) and α-eleostearic acid methyl ester (2) with several olefins, including 1-hexene, dimethyl maleate and cis-stilbene as model compounds has been carried out using (1,3-bis-(2,4,6-trimethylphenyl)-2-imidazolidinylidene)-dichloro(o-isopropoxyphenylmethylene)ruthenium (Hoveyda-Grubbs 2nd generation, HG2) catalyst. The feasibility of these reactions is demonstrated by the observed high conversions and reasonable yields. Thus, regardless of the relatively low electron density, =CH–CH= conjugated units of molecules, including compound 2 as a sustainable, non-foodstuff source, can be utilized as building blocks for the synthesis of various value-added chemicals via olefin metathesis. DFT-studies and the product spectrum of the self-metathesis of 1,6-diphenyl-1,3,5-hexatriene suggest that a Ru η1-allylidene complex is the active species in the reaction.
- Kovács, Ervin,Sághy, Péter,Turczel, Gábor,Tóth, Imre,Lendvay, Gy?rgy,Domján, Attila,Anastas, Paul T.,Tuba, Róbert
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supporting information
p. 213 - 217
(2017/09/12)
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- Synthesis of Unsymmetric Monosubstituted and Disubstituted Dinaphthothiophenes
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Dinaphthothiophenes (DNTs) are a class of compounds with potential uses in organic semiconductors and the synthesis of unsymmetric catalysts. Symmetrical or asymmetrical addition of functional groups to the DNT structure may be desired for steric bulk in binaphthyl catalyst synthesis or tuning the electronic properties of semiconductors. Thus, versatility of functional group addition is a great asset in DNT synthesis. Until now, no versatile and concise methods for the synthesis of unsymmetrically substituted DNTs have been reported. Herein, we report three synthetic routes for the creation of three different classes of DNTs. Each route involves the successive addition of two functionalized styryl groups to a thiophene ring, followed by a photocyclization to form the desired asymmetric DNT. Various novel unsymmetrically monosubstituted and disubstituted dinaphtho[2,1-b:1′,2′-d]thiophenes, dinaphtho[1,2-b:1′,2′-d]thiophenes, and dinaphtho[1,2-b:2′,1′-d]thiophenes were synthesized from 2-bromothiophene,2,4-dibromothiophene, and 3,4-dibromothiophene in three or four steps. These methods can be used to synthesize a wide variety of unsymmetrically functionalized DNTs.
- Throgmorton, John C.,Chintala, Satyanarayana M.,McCulla, Ryan D.
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supporting information
p. 3682 - 3688
(2017/10/09)
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- Unsupported Nanoporous Gold Catalyst for Chemoselective Hydrogenation Reactions under Low Pressure: Effect of Residual Silver on the Reaction
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For the first time, H-H dissociation on an unsupported nanoporous gold (AuNPore) surface is reported for chemoselective hydrogenation of C=C, C=C, C=N, and C=O bonds under mild conditions (8 atm H2 pressure, 90 °C). Silver doping in AuNPore, which was inevitable for its preparation through a process of dealloying of Au-Ag alloy, exhibited a remarkable difference in catalytic activity between two catalysts, Au>99Ag1NPore and Au90Ag10NPore.The former was more active and the latter less active in H2 hydrogenation, while the reverse tendency was observed for O2 oxidation. This marked contrast between H2 reduction and O2 oxidation is discussed. Further, Au>99Ag1NPore showed a high chemoselectivity toward reduction of terminal alkynes in the presence of internal alkynes which was not achieved using supported gold nanoparticle catalysts and other previously known methods. Reductive amination, which has great significance in synthesis of amines due to its atom-economical nature, was also realized using Au>99Ag1NPore, and the Au>99Ag1NPore/H2 system showed a preference for the reduction of aldehydes in the presence of imines. In addition to this high chemoselectivity, easy recovery and high reusability of AuNPore make it a promising heterogeneous catalyst for hydrogenation reactions.
- Takale, Balaram S.,Feng, Xiujuan,Lu, Ye,Bao, Ming,Jin, Tienan,Minato, Taketoshi,Yamamoto, Yoshinori
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supporting information
p. 10356 - 10364
(2016/08/31)
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- Stereoselective alkyne semihydrogenations with an air-stable copper(i) catalyst
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An air-stable and preactivated copper(i) hydroxide/N-heteroyclic carbene (NHC) complex for alkyne semihydrogenations is reported. Next to an enhanced practicability of the process, the resulting alkenes are obtained with high Z-selectivities and no overreduction to the corresponding alkanes.
- Thiel, Niklas O.,Teichert, Johannes F.
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p. 10660 - 10666
(2016/11/30)
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- Enantioselective Palladium-Catalyzed Alkenylation of Trisubstituted Alkenols to Form Allylic Quaternary Centers
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In this report, we describe the generation of remote allylic quaternary stereocenters β, γ, and δ relative to a carbonyl in high enantioselectivity. We utilize a redox-relay Heck reaction between alkenyl triflates and acyclic trisubstituted alkenols of varying chain-lengths. A wide array of terminal (E)-alkenyl triflates are suitable for this process. The utility of this functionalization is validated further by conversion of the products, via simple organic processes to access remotely functionalized chiral tertiary acid, amine, and alcohol products.
- Patel, Harshkumar H.,Sigman, Matthew S.
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p. 14226 - 14229
(2016/11/13)
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- Direct Olefination of Alcohols with Sulfones by Using Heterogeneous Platinum Catalysts
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Carbon-supported Pt nanoparticles (Pt/C) were found to be effective heterogeneous catalysts for the direct Julia olefination of alcohols in the presence of sulfones and KOtBu under oxidant-free conditions. Primary alcohols, including aryl, aliphatic, allyl, and heterocyclic alcohols, underwent olefination with dimethyl sulfone and aryl alkyl sulfones to give terminal and internal olefins, respectively. Secondary alcohols underwent methylenation with dimethyl sulfone. Under 2.5 bar H2, the same reaction system was effective for the transformation of alcohol OH groups to alkyl groups. Structural and mechanistic studies of the terminal olefination system suggested that Pt0 sites on the Pt metal particles are responsible for the rate-limiting dehydrogenation of alcohols and that KOtBu may deprotonate the sulfone reagent. The Pt/C catalyst was reusable after the olefination, and this method showed a higher turnover number (TON) and a wider substrate scope than previously reported methods, which demonstrates the high catalytic efficiency of the present method. Olefination of alcohols: The first heterogeneous catalytic terminal and internal olefination of primary alcohols and methylenation of secondary alcohols with sulfones, a reusable carbon-supported Pt catalyst, and KOtBu is reported (see scheme).
- Hakim Siddiki,Touchy, Abeda Sultana,Kon, Kenichi,Shimizu, Ken-Ichi
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p. 6111 - 6119
(2016/04/26)
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- Synthesis of Buta-1,3-dienes through Palladium-Catalyzed Homocoupling of Aromatic Alkenes
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A series of buta-1,3-dienes have been directly synthesized via a convenient palladium-catalyzed homodehydrogenation coupling reaction of aromatic alkenes under mild conditions. The homocoupling reaction enables a rapid synthesis of multisubstituted butadiene which shows typical aggregation-induced emission enhancement (AIEE) characteristics because it is practically not emissive in solution but emits blue fluorescence in aggregates.
- Wen, Yanmei,Xie, Jianying,Deng, Chunmei,Wu, Yulian
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supporting information
p. 1755 - 1758
(2015/07/20)
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- Salt-Free Reduction of Nonprecious Transition-Metal Compounds: Generation of Amorphous Ni Nanoparticles for Catalytic C-C Bond Formation
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A salt-free procedure for the generation of a wide variety of metal(0) particles, including Fe, Co, Ni, and Cu, was achieved using 2,3,5,6-tetramethyl-1,4-bis(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene (1), which reduced the corresponding metal precursors under mild conditions. Notably, Ni particles formed in situ from the treatment of Ni(acac)2 (acac=acetylacetonate) with 1 in toluene exhibited significant catalytic activity for reductive C-C bond-forming reactions of aryl halides in the presence of excess amounts of 1. By examination of high-magnification transmission electron microscopy images and electron diffraction patterns, we concluded that amorphous Ni nanoparticles (Ni aNPs) were essential for the high catalytic activity.
- Yurino, Taiga,Ueda, Yohei,Shimizu, Yoshiki,Tanaka, Shinji,Nishiyama, Haruka,Tsurugi, Hayato,Sato, Kazuhiko,Mashima, Kazushi
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supporting information
p. 14437 - 14441
(2016/01/25)
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- (E)-Specific direct Julia-olefination of aryl alcohols without extra reducing agents promoted by bases
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An unprecedented base-promoted direct olefination of aryl alcohols with sulfones via a Julia-type reaction has been described. No extra reductants are needed for Julia reaction since alcohols work as double sources of aldehydes and the hydride. Generally high yields were given for both terminal and highly (E)-selective internal olefins.
- Yao, Chuan-Zhi,Li, Qiang-Qiang,Wang, Mei-Mei,Ning, Xiao-Shan,Kang, Yan-Biao
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supporting information
p. 7729 - 7732
(2015/05/12)
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- Efficient E-Selective Transfer Semihydrogenation of Alkynes by Means of Ligand-Metal Cooperating Ruthenium Catalyst
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The manuscript describes an efficient protocol for the E-selective transfer semihydrogenation of internal alkynes employing a previously described bifunctional ruthenium-based PC(sp3)P complex, 20'mol% of sodium formate and nearly stoichiometric formic acid. Semihydrogenation of the terminal alkynes results in the formation of the corresponding styrenes. The mechanism of the reaction includes stepwise transfer of both the hydride and the proton of the formic acid to the substrate. This fact allowed for the development of a facile protocol for the synthesis of monodeuterated alkenes by simply applying formic acid/sodium formate/D2O mixture as a hydrogen source. High yields, selectivity and functional group compatibility have been generally achieved.
- Musa, Sanaa,Ghosh, Amrita,Vaccaro, Luigi,Ackermann, Lutz,Gelman, Dmitri
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supporting information
p. 2351 - 2357
(2015/07/27)
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- Catalytic wittig reactions of semi- and nonstabilized ylides enabled by ylide tuning
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The first examples of catalytic Wittig reactions with semistabilized and nonstabilized ylides are reported. These reactions were enabled by utilization of a masked base, sodium tert-butyl carbonate, and/or ylide tuning. The acidity of the ylide-forming proton was tuned by varying the electron density at the phosphorus center in the precatalyst, thus facilitating the use of relatively mild bases. Steric modification of the precatalyst structure resulted in significant enhancement of E selectivity up to >95:5, E/Z. Time for a tune up: Catalytic Wittig reactions with semi- and nonstabilized ylides were enabled by use of a masked base (NaOCO2tBu) and/or ylide tuning. The acidity of the ylide-forming proton was tuned by varying the electron density at the P center in the precatalyst, thus facilitating the use of relatively mild bases. Steric modification of the precatalyst structure resulted in significant enhancement of E selectivity.
- Coyle, Emma E.,Doonan, Bryan J.,Holohan, Andrew J.,Walsh, Killian A.,Lavigne, Florie,Krenske, Elizabeth H.,O'Brien, Christopher J.
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supporting information
p. 12907 - 12911
(2016/02/18)
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- METHODS FOR PHOSPHINE OXIDE REDUCTION IN CATALYTIC WITTIG REACTIONS
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A method for increasing the rate of phosphine oxide reduction, preferably during a Wittig reaction comprising use of an acid additive is provided. A room temperature catalytic Wittig reaction (CWR) the rate of reduction of the phosphine oxide is increased due to the addition of the acid additive is described. Furthermore, the extension of the CWR to semi-stabilized and non-stabilized ylides has been accomplished by utilization of a masked base and/or ylide-tuning.
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Page/Page column 58; 59; 62
(2014/09/29)
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- Stereospecific hydrodehalogenation of alkenyl bromides: A new approach to the synthesis of (E)-alkenes
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The pair NaBH4-TMEDA and catalytic PdCl2(PPh 3)2 in THF at room temperature is a mild and efficient system for the hydrodebromination of alkenyl bromides, providing a facile reduction procedure that allows completing the process advantageously, leading from aldehydes to (E)-alkenes. This journal is the Partner Organisations 2014.
- Chelucci, Giorgio
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p. 4069 - 4072
(2014/04/03)
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- Quinonediimine-induced oxidative coupling of organomagnesium reagents
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N,N′-Diphenyl-p-benzoquinonediimine, a redox-active unit of polyaniline, efficiently induced the oxidative homocoupling of various aryl- and vinylmagnesium reagents in suppressing the side reactions, such as 1,2- or 1,4-addition reaction. Copyright
- Amaya, Toru,Suzuki, Riyo,Hirao, Toshikazu
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p. 653 - 656
(2014/01/23)
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- Direct catalytic olefination of alcohols with sulfones
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The synthesis of terminal as well as internal olefins was achieved by the one-step olefination of alcohols with sulfones catalyzed by a ruthenium pincer complex. Furthermore performing the reaction with dimethyl sulfone under mild hydrogen pressure provides a direct route for the replacement of alcohol hydroxy groups by methyl groups in one step.
- Srimani, Dipankar,Leitus, Gregory,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 11092 - 11095
(2015/03/30)
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- Dilithium tetrachlorocuprate(II) catalyzed oxidative homocoupling of functionalized grignard reagents
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An efficient procedure is described for the oxidative homocoupling of functionalized Grignard reagents using a catalytic amount of dilithium tetrachlorocuprate(II) (CuLi2Cl4) in the presence of pure oxygen gas. This method is applied successfully to a variety of aryl, heteroaryl, alkyl, alkenyl and alkynyl halides, which are converted into the corresponding homocoupled products in good to excellent yields. Georg Thieme Verlag Stuttgart · New York.
- Hua, Si-Kai,Hu, Qiu-Peng,Ren, Jiangmeng,Zeng, Bu-Bing
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p. 518 - 526
(2013/03/29)
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- Iron-catalyzed homocoupling of aryl halides and derivatives in the presence of alkyllithiums
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Direct synthesis of biaryl derivatives from aryl halides takes place under very mild temperature conditions by using a ligand-free iron catalytic system. The procedure, which proceeds via an in situ quantitative aryl halide exchange with alkyllithiums, allows for excellent control of the reactivity and is in line with the sustainable development. The method is also applicable to styryl and benzyl halides and to phenylacetylene.
- Toummini, Dounia,Ouazzani, Fouad,Taillefer, Marc
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supporting information
p. 4690 - 4693
(2013/10/08)
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- Fe3O4 nanoparticle-supported Cu(ii)-β- cyclodextrin complex as a magnetically recoverable and reusable catalyst for the synthesis of symmetrical biaryls and 1,2,3-triazoles from aryl boronic acids
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We report here on the preparation of an efficient, easily recoverable and reusable Fe3O4 magnetic nanoparticle-supported Cu(ii)-β-cyclodextrin complex catalyst for the synthesis of symmetrical biaryls and 1,2,3-triazoles from arylboronic acids. The presented Fe 3O4 magnetic nanoparticle-supported Cu(ii)-β- cyclodextrin complex catalyst was characterized by TEM, XRD, VSM, TGA, and FT-IR spectrometer. By using the catalyst, we have developed an efficient protocol for the homocoupling of aryl boronic acids for the synthesis of biaryls. The catalyst is also active in the synthesis of 1,2,3-triazoles via a one-pot reaction of an arylboronic acid with sodium azide in water followed by a click cyclization reaction with an alkyne at room temperature in air without any additives. The reusability of the prepared nanocatalyst was successfully examined four times with only a very slight loss of catalytic activity.
- Kaboudin, Babak,Mostafalu, Ramin,Yokomatsu, Tsutomu
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p. 2266 - 2274
(2013/09/24)
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- Copper(I)-catalyzed alkylation of aryl- and alkenylsilanes activated by intramolecular coordination of an alkoxide
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Let's coordinate: Copper(I)-catalyzed cross-coupling of alkenyl- and arylsilanes with primary alkyl iodides as well as allylic and benzylic halides as C(sp3)-X electrophilic coupling partners has been realized by intramolecular activation through alkoxide coordination. This alkylation tolerates a range of functional groups including a free hydroxy group. IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene. Copyright
- Tsubouchi, Akira,Muramatsu, Daisuke,Takeda, Takeshi
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p. 12719 - 12722
(2013/12/04)
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- Regio- and stereoselective hydrosilylation of 1,3-enynes catalyzed by palladium
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In the presence of Pd(0) and a phosphine, hydrosilylation of 1,3-enynes with Me2SiHCl proceeds to yield dienylsilanes with the silicon function added to the internal alkyne carbon atom and with (E)-configuration of newly formed olefinic bond. The silanols isolated after hydrolysis of the primarily obtained products serve as precursors to conjugated dienes with different substitution patterns.
- Zhou, Hui,Moberg, Christina
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p. 1444 - 1447
(2013/06/27)
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- Oxidative cross-coupling of vinylsilanes in water
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Palladium-promoted cross-dimerization reaction of alkenylsilanes is reported for the first time, which is also one of the very first studies on oxidative cross-coupling between vinylic organometallic reagents. The reaction occurs at room temperature in aqueous micelles and represents a convenient access to all-trans push-pull butadienes.
- Cicco, Stefania R.,Martinelli, Carmela,Pinto, Vita,Naso, Francesco,Farinola, Gianluca M.
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- Efficient stille cross-coupling reaction catalysed by the Pd(OAc) 2/orotic acid catalytic system
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An efficient Pd(OAc)2/orotic acid catalytic system has been developed for the Stille cross-coupling reaction. In the presence of Pd(OAc)2 and orotic acid, various halides including aryl iodides, aryl bromides, vinyl bromides, and aryl chlorides were coupled efficiently with aryl- and vinyltin compounds to afford the corresponding biaryls and stilbenes. The high catalytic efficacy of Pd(OAc)2/orotic acid has also been demonstrated.
- Zhang, Hong-Ping,Li, Xiao-Fang,Li, Hong-Yan
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p. 219 - 222
(2013/07/05)
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- Cross-coupling of aryllithiums with aryl and vinyl halides in flow microreactors
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The use of Pd catalysts that contained a carbene ligand, such as PEPPSI-SIPr, speeded up the Murahashi coupling of ArLi with ArBr, by enabling its integration with the Br/Li exchange of ArBr with BuLi in flow. Space integration realized the rapid cross-coupling of two different ArBr substrates. However, the cross-coupling reaction with vinyl halides could not be achieved under similar conditions. Pd(OAc)2 was an effective catalyst, and the space integration of the Br/Li exchange of ArBr with BuLi and the Murahashi coupling with vinyl halides was successfully achieved.
- Nagaki, Aiichiro,Moriwaki, Yuya,Haraki, Suguru,Kenmoku, Akira,Takabayashi, Naofumi,Hayashi, Atsushi,Yoshida, Jun-Ichi
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supporting information; experimental part
p. 1061 - 1068
(2012/07/31)
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