104-51-8Relevant articles and documents
Synthesis of insoluble polystyrene-supported flavins and their catalysis in aerobic reduction of olefins
Arakawa, Yukihiro,Kawachi, Risa,Tezuka, Yoshihiko,Minagawa, Keiji,Imada, Yasushi
, p. 1706 - 1713 (2017)
2′,4′-p-Vinylbenzylideneriboflavin (2′,4′-PVBRFl) was prepared as a flavin-containing monomer and copolymerized with divinylbenzene and styrene or its p-substituted derivatives such as 4-acetoxystyrene, 4-vinylbenzyl alcohol, and 4-vinylbenzoic acid to give the corresponding non-functionalized and functionalized PS-DVB-supported flavins PS(H)-DVB-Fl, PS(OAc)-DVB-Fl, PS(CH2OH)-DVB-Fl, and PS(COOH)-DVB-Fl, respectively. PS(OH)-DVB-Fl was also prepared by hydrolysis of PS(OAc)-DVB-Fl under basic conditions. These novel flavin-containing insoluble polymers exhibited characteristic fluorescence in solid state, except PS(OH)-DVB-Fl, and different catalytic activities in aerobic reduction of olefins by in situ generated diimide from hydrazine depending on their pendant functional group. For example, PS(H)-DVB-Fl was found to be particularly effective for neutral hydrophobic substrates, which could be readily recovered by a simple filtration and reused more than 10 times without loss in catalytic activity. On the other hand, PS(OH)-DVB-Fl and PS(COOH)-DVB-Fl proved to be highly active for phenolic substrates known to be less reactive in the reaction with conventional non-supported flavin catalysts.
Shultz,Linden
, p. 2011,2013, 2014 (1957)
Alkene Hydrogenations by Soluble Iron Nanocluster Catalysts
Gieshoff, Tim N.,Chakraborty, Uttam,Villa, Matteo,Jacobi von Wangelin, Axel
, p. 3585 - 3589 (2017)
The replacement of noble metal technologies and the realization of new reactivities with earth-abundant metals is at the heart of sustainable synthesis. Alkene hydrogenations have so far been most effectively performed by noble metal catalysts. This study reports an iron-catalyzed hydrogenation protocol for tri- and tetra-substituted alkenes of unprecedented activity and scope under mild conditions (1–4 bar H2, 20 °C). Instructive snapshots at the interface of homogeneous and heterogeneous iron catalysis were recorded by the isolation of novel Fe nanocluster architectures that act as catalyst reservoirs and soluble seeds of particle growth.
Scope and Limitations of the Palladium-Catalyzed Cross-Coupling Reaction of in Situ Generated Organoboranes with Aryl and Vinyl Halides
Maddaford, Shawn P.,Keay, Brian A.
, p. 6501 - 6503 (1994)
The in situ palladium(0)-catalyzed Suzuki reaction is shown to be an efficient method for the cross-coupling of aryl-, furyl-, primary, and benzylic boranes with aryl or vinyl bromides and iodides without the isolation of the organoboronic acid or the addition of any external base.
Divergent Reactivity of Stannane and Silane in the Trifluoromethylation of PdII: Cyclic Transition State versus Difluorocarbene Release
Pu, Maoping,Sanhueza, Italo A.,Senol, Erdem,Schoenebeck, Franziska
, p. 15081 - 15085 (2018)
The transmetalation is a key elementary step in cross-coupling reactions. Yet, the precise nature of its mechanism and transition state geometry are frequently elusive. This report discloses our study of the transmetalation of [PdII]-F complexes with the silane- and stannane-based trifluoromethylation agents, R3SiCF3 and R3SnCF3. A divergent reactivity was uncovered, with the stannane showing selective R-group transfer, and the silane selective CF3-group transfer. Using a combined experimental and computational approach, we uncovered a hitherto unrecognized transmetalation mechanism with the widely employed R3SiCF3 reagent, explaining its unique activity in metal-catalyzed trifluoromethylations. While the stannane reacts via a cyclic, 4-membered transition state, the silane undergoes a fundamentally different pathway and releases a difluorocarbene in the transmetalation event. Molecular dynamics studies clearly reinforced the liberation of a free CF2 carbene, which reacts with [PdII]-F to ultimately generate [PdII]-CF3.
Craig,Larrabee
, p. 1195 (1951)
Cross-coupling in a flow microreactor: Space integration of lithiation and murahashi coupling
Nagaki, Aiichiro,Kenmoku, Akira,Moriwaki, Yuya,Hayashi, Atsushi,Yoshida, Jun-Ichi
, p. 7543 - 7547 (2010)
Going with the flow: The use of palladium catalysts bearing a carbene ligand resulted in a faster Murahashi coupling, and enabled its integration with the Br-Li exchange of ArBr with Bu-Li in a microreactor (see picture). This system allows the cross-coupling of two different arylbromides within a minute without necessitating low temperatures (-78°C).
Solventless Suzuki coupling reactions on palladium-doped potassium fluoride alumina
Kabalka, George W.,Wang, Lei,Pagni, Richard M.,Hair, C. Maxwell,Namboodiri, Vasudevan
, p. 217 - 222 (2003)
A solventless Suzuki coupling reaction has been developed which utilizes a commercially available potassium fluoride alumina mixture and palladium powder. The new reaction is convenient, environmentally friendly, and generates good yields of the coupled products. Aryl iodides react faster than the bromides or chlorides; aryl groups are also more reactive than alkenyl groups, which react faster than alkyl groups. The use of microwave irradiation accelerates the reaction, decreasing reaction times from hours to minutes. The palladium powder catalyst can be recycled using a simple filtration and washing sequence without loss of catalytic activity.
Nickel- and palladium-catalyzed cross-coupling reaction of polyfluorinated arenes and alkenes with grignard reagents
Saeki, Tomoyuki,Takashima, Yohei,Tamao, Kohei
, p. 1771 - 1774 (2005)
The cross-coupling reaction of fluorobenzene with an aryl Grignard reagent has been reinvestigated which revealed that the reaction readily proceeds under ordinary conditions using a catalytic amount of NiCl2(dppp) even at room temperature. The use of nickel catalysts and Grignard reagent is essential for the activation of the carbon-fluorine bond. The palladium catalyst is also effective for the 1,2-difluorobenzene and trifluorobenzenes to selectively produce the corresponding mono-coupled products while the nickel-based catalyst system affords a mixture of the mono-coupled product and di- or tri-coupled product. Georg Thieme Verlag Stuttgart.
Side-chain alkylation of toluene with propene on caesium/nanoporous carbon catalysts
Stevens, Mark G.,Anderson, Melony R.,Foley, Henry C.
, p. 413 - 414 (1999)
Caesium/nanoporous carbon materials are powerful solid-base catalysts, promoting the side-chain alkylation toluene with propene in a continuous flow reactor conditions as mild as 150°C and 50 psig.
Batch to flow deoxygenation using visible light photoredox catalysis
Nguyen, John D.,Reiss, Barbara,Dai, Chunhui,Stephenson, Corey R. J.
, p. 4352 - 4354 (2013)
Herein we report a one-pot deoxygenation protocol for primary and secondary alcohols developed via the combination of the Garegg-Samuelsson reaction, visible light-photoredox catalysis, and flow chemistry. This procedure is characterized by mild reaction conditions, easy-to-handle reactants and reagents, excellent functional group tolerance, and good yields.
PHOTOCHEMICAL TRANSFORMATIONS - V ORGANIC IODIDES (Part 4) : SOLUTION PHOTOCHEMISTRY OF 4-PHENYL-1-IODOBUTANE AND 4-PHENYL-1-BROMOBUTANE
Subbarao, Kanury V.,Damodaran, N.P.,Dev, Sukh
, p. 2543 - 2548 (1987)
Evidence is presented to show that product development from photolysis of 4-phenyl-1-iodobutane occurs essentially from an ionic species.This conclusion is in accord with our earlier suggestion that in the photocyclization of citronellyl iodide and related compounds, carbocations are involved.
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Kharasch,Lewis,Reynolds
, p. 498 (1943)
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Andersen,Fenton
, p. 3270 (1964)
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Nasarowa,Zukerwanik
, (1948)
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PREPARATION OF ALKYLBENZENES FROM 1-ALKYLCYCLOHEX-2-ENOLS VIA TRICARBONYLIRON COMPLEXES
Farcasiu, D.,Marino, Gaye
, p. 243 - 248 (1983)
Tertiary cyclohex-2-enols are converted directly to the related tricarbonyl-1,3-cyclohexadieneiron complexes, in good yield.Tricarbonylcyclohexadienyliron salts are conveniently oxidized to the corresponding alkylbenzenes, by cerium(IV) salts.These reactions were incorporated in a procedure of converting the cyclohexenols to aromatics, suitable for the preparation of materials specifically labelled with carbon isotopes.
Tetramethylammonium phenyltrialkylborates in the photoinduced electron transfer reaction with benzophenone. Generation of alkyl radicals and their addition to activated alkenes
Polykarpov, Alexander Y.,Neckers, Douglas C.
, p. 5483 - 5486 (1995)
Photoinduced one electron oxidation of tetramethylammonium phenyltrialkylborates by the excited state of benzophenone in an acetonitrile/benzene solution containing an excess of activated alkene produces substantially more than one equivalent of the alkyl radicals. The corresponding adducts of alkyl radicals to the alkenes are produced in good yields. No phenyl radical adducts are observed.
Efficient and facile Ar-Si bond cleavage by montmorillonite KSF: Synthetic and mechanistic aspects of solvent-free protodesilylation studied by solution and solid-state MAS NMR
Zafrani, Yossi,Gershonov, Eytan,Columbus, Ishay
, p. 7014 - 7017 (2007)
(Chemical Equation Presented) A facile and efficient method for the cleavage of the Ar-Si bond of various aryl trimethyl silanes is described. When adsorbed on montmorillonite KSF (mont KSF), these aryl-silanes readily undergo a solvent-free protodesilylation to the corresponding arenes at room temperature in excellent yields. This approach seems to be superior to the traditional mild methods (i.e., desilylation by TFA, TBAF, CsF), in terms of reaction yield, rate, and environmentally benign conditions. Some mechanistic studies using both solution and solid-state magic-angle spinning (SS MAS) 1H NMR are also presented.
Palladium-indium-indium(III) chloride-mediated allyl cross-coupling reactions using allyl acetates
Lee, Phil Ho,Seomoon, Dong,Lee, Kooyeon,Kim, Sundae,Kim, Hyunseok,Kim, Hyun,Shim, Eunkyong,Lee, Miae,Lee, Seokju,Kim, Misook,Sridhar, Madabhushi
, p. 1641 - 1645 (2004)
Allylindiums in situ generated by reductive transmetalation of π-allylpalladium(II) complexes, obtained from allyl acetates and palladium(0) catalyst, with indium and indium(III) chloride are effective nucleophilic cross-coupling partners in Pd-catalyzed allyl cross-coupling reactions with a variety of electrophilic cross-coupling partners.
Higher-order zincates as transmetalators in alkyl-alkyl Negishi cross-coupling
McCann, Lucas C.,Hunter, Howard N.,Clyburne, Jason A. C.,Organ, Michael G.
, p. 7024 - 7027 (2012)
Negishi revisited: Higher-order alkyl zincates have been subjected to Negishi coupling with alkyl bromides. For the first time, coupling takes place in straight THF, i.e., without a salt additive and a high dielectric co-solvent. This provides evidence that it is the higher-order zincate that undergoes transmetalation to Pd, and not mono-anionic zincates or any of the other species present in the Schlenk equilibrium. Copyright
Preparation of flavin-containing mesoporous network polymers and their catalysis
Arakawa, Yukihiro,Sato, Fumiaki,Ariki, Kenta,Minagawa, Keiji,Imada, Yasushi
, (2020)
Riboflavin tetramethacrylate (RFlTMA) was prepared as a flavin monomer and copolymerized with ethylene glycol dimethacrylate (EGDMA) under polymerization-induced phase separation conditions. The resulting flavin-containing mesoporous network polymer, poly(RFlTMA-co-EGDMA), was found to be a more effective catalyst than riboflavin tetraacetate (RFlTA), a soluble analogue, for aerobic hydrogenation of olefins despite its heterogeneity, which allowed for its multiple recovery and reuse through simple filtrations and washings without loss in catalytic activity. In addition, the polymeric flavin was demonstrated to be utilized also as an effective photocatalyst in the oxidation of benzyl alcohols.
Childs,Johnson
, p. 874 (1967)
Mononuclear calcium complex as effective catalyst for alkenes hydrogenation
Shi, Xianghui,Hou, Cuiping,Zhao, Lanxiao,Deng, Peng,Cheng, Jianhua
, p. 5162 - 5165 (2020)
Hydrogenolysis of the scorpionate-supported calcium benzyl complex [(TpAd,iPr)Ca(p-CH2C6H4-Me)(THP)] (TpAd,iPr= hydrotris(3-adamantyl-5-isopropyl-pyrazolyl)borate, THP = tetrahydropyran) (2-THP) afforded the mononuclear calcium hydrido complex [(TpAd,iPr)Ca(H)(THP)] (3). Under mild conditions (40 °C, 10 atm H2, 5 mol% cat.), complex3effectively catalyzed the hydrogenation of a variety of alkenes, including activated alkenes, semi-activated alkenes, non-activated terminal and internal alkenes. Mononuclear calcium unsubstituted alkyl complex [(TpAd,iPr)Ca{(CH2)4Ph}(THP)] (6), proposed as the catalytic hydrogenation intermediate, was isolated and structurally characterized.
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Broadbent,H.S.,Seegmiller,D.W.
, p. 2347 - 2350 (1963)
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Cyanophenylation of aromatic nitriles by terephthalonitrile dianion: Is the charge-transfer complex a key intermediate?
Panteleeva, Elena V.,Shchegoleva, Lyudmila N.,Vysotsky, Viktor P.,Pokrovsky, Leonid M.,Shteingarts, Vitalij D.
, p. 2558 - 2565 (2005)
The interaction of terephthalonitrile (1) dianion (12-) with benzonitrile (2) or m-tolunitrile (3) provides 4,4′-dicyanobiphenyl (4) or 4,4′-dicyano-2-methylbiphenyl (5), respectively. This result shows that dianion 12- serves as a reagent for p-cyanophenylation of aromatic nitriles. Based on experimental data, such as the chemical trapping of the 4,4′-dicyanobiphenyl precursor 4-cyano-1-(p-cyanophenyl)cyclohexa-2,5-dienyl anion (7) and the failure to obtain biphenyl 4 through the interaction of independently generated radical anions (RAs) 1- and 2-, as well as on the results of quantum-chemical calculations, a mechanism is suggested that includes a charge-transfer complex (CTC) between 12- and the aromatic nitrile as the key intermediate. The formation of this CTC is followed either by an intracomplex electron transfer (ET) and recombination of terephthalonitrile and aromatic nitrile RAs within an unequilibrated RA pair, or by synchronous ET and bonding of the ipso-carbon atom of terephthalonitrile with the p-carbon atom of the aromatic nitrile. The synthetic significance of p-cyanophenylation of arenecarbonitriles by dianion 12- is illustrated by the high yield of biphenyl product 4 (approx. 90%) as well as by the possibility of a one-pot synthesis of 4-butyl-4′-cyanobiphenyl and 4-butyl-4′-cyano-2-methylbiphenyl by successive treatment of dianion 12- with nitrile 2 or 3 and butyl bromide. Wiley-VCH Verlag GmbH & Co, KGaA, 69451 Weinheim, Germany, 2005.
Cobalt-catalyzed alkene hydrogenation by reductive turnover
van der Puyl, Vincent,McCourt, Ruairi O.,Shenvi, Ryan A.
supporting information, (2021/04/19)
Earth abundant metal catalysts hold advantages in cost, environmental burden and chemoselectivity over precious metal catalysts. Differences in reactivity for a given metal center result from ligand field strength, which can promote reaction through either open- or closed-shell carbon intermediates. Herein we report a simple protocol for cobalt-catalyzed alkene reduction. Instead of using an oxidative turnover mechanism that requires stoichiometric hydride, we find a reductive turnover mechanism that requires stoichiometric proton. The reaction mechanism appears to involve coordination and hydrocobaltation of terminal alkenes.
Selective upgrading of biomass-derived benzylic ketones by (formic acid)–Pd/HPC–NH2 system with high efficiency under ambient conditions
Chen, Yuzhuo,Chen, Zhirong,Gong, Yutong,Mao, Shanjun,Ning, Honghui,Wang, Yong,Wang, Zhenzhen
, p. 3069 - 3084 (2021/11/16)
Upgrading biomass-derived phenolic compounds provides a valuable approach for the production of higher-value-added fuels and chemicals. However, most established catalytic systems display low hydrodeoxygenation (HDO) activities even under harsh reaction conditions. Here, we found that Pd supported on –NH2-modified hierarchically porous carbon (Pd/HPC–NH2) with formic acid (FA) as hydrogen source exhibits unprecedented performance for the selective HDO of benzylic ketones from crude lignin-derived oxygenates. Designed experiments and theoretical calculations reveal that the H+/H? species generated from FA decomposition accelerates nucleophilic attack on carbonyl carbon in benzylic ketones and the formate species formed via the esterification of intermediate alcohol with FA expedites the cleavage of C–O bonds, achieving a TOF of 152.5 h?1 at 30°C for vanillin upgrading, 15 times higher than that in traditional HDO processes (～10 h?1, 100°C–300°C). This work provides an intriguing green route to produce transportation fuels or valuable chemicals from only biomass under mild conditions.
Amido PNP pincer complexes of palladium(II) and platinum(II): Synthesis, structure, and reactivity
Huang, Mei-Hui,Lee, Wei-Ying,Zou, Xue-Ru,Lee, Chia-Chin,Hong, Sheng-Bo,Liang, Lan-Chang
, (2020/12/15)
The synthesis of a series of divalent palladium and platinum complexes containing amido PNP pincer ligands of the type [N(o-C6H4PR2)2]? (R = Ph (1a), iPr (1b)) is reported. Metathetical reactions of [1a–b]PdCl or [1a–b]PtCl with a variety of alkyl Grignard reagents or LiHBEt3 in ethereal or arene solutions generate their corresponding alkyl or hydride complexes [1a]PdR1 (R1 = Me, Et, nBu), [1b]PdR1 (R1 = Me, Et, H), [1a]PtR1 (R1 = Me, Et, nBu, nHexyl, H), and [1b]PtR1 (R1 = Me, H). Although these organometallic complexes are all thermally stable, including those containing β-hydrogen atoms even at elevated temperatures, compounds [1a]PdH and [1b]PtR1 (R1 = Et, nBu, nHexyl) are not isolable due to facile decomposition. The stability and reactivity of these complexes are discussed. The chloro [1a]PdCl is a superior catalyst precursor to [1b]PdCl, [1a]PtCl, and [1b]PtCl in Kumada couplings, affording, for instance, n-butyl arenes nearly quantitatively. The X-ray structures of [1b]PtCl, [1b]PtMe, [1b]PdEt, [1a]PtnBu, [1b]PdH, and [1b]PtH are presented.
