103-29-7Relevant articles and documents
Electrochemical synthesis of aromatic sulfur compounds in ionic liquids
Okhlobystina,Okhlobystin,Letichevskaya,Abdulaeva,Movchan,Berberova
, p. 291 - 295 (2016)
Electrochemical properties of ionic liquids (pyridinium and imidazolium salts) and the effect of additives of organic solvents on the electrochemical determination of organic compounds in ionic liquids have been studied. Transformations of aromatic and aliphatic sulfur compounds in ionic liquids in the presence of aromatic substrates are discussed. A new method has been proposed for identification of organic sulfur compounds-gas chromatography on columns with ionic liquid as the active phase.
Decamethyltitanocene hydride intermediates in the hydrogenation of the corresponding titanocene-(η2-ethene) or (η2-alkyne) complexes and the effects of bulkier auxiliary ligands
Pinkas, Ji?í,Gyepes, Róbert,Císa?ová, Ivana,Kubi?ta, Ji?í,Horá?ek, Michal,Mach, Karel
, p. 8229 - 8244 (2017)
1H NMR studies of reactions of titanocene [Cp?2Ti] (Cp? = η5-C5Me5) and its derivatives [Cp?(η5:η1-C5Me4CH2)TiMe] and [Cp?2Ti(η2-CH2CH2)] with excess dihydrogen at room temperature and pressures lower than 1 bar revealed the formation of dihydride [Cp?2TiH2] (1) and the concurrent liberation of either methane or ethane, depending on the organometallic reactant. The subsequent slow decay of 1 yielding [Cp?2TiH] (2) was mediated by titanocene formed in situ and controlled by hydrogen pressure. The crystalline products obtained by evaporating a hexane solution of fresh [Cp?2Ti] in the presence of hydrogen contained crystals having either two independent molecules of 1 in the asymmetric part of the unit cell or cocrystals consisting of 1 and [Cp?2Ti] in a 2:1 ratio. Hydrogenation of alkyne complexes [Cp?2Ti(η2-R1CCR2)] (R1 = R2 = Me or Et) performed at room temperature afforded alkanes R1CH2CH2R2, and after removing hydrogen, 2 was formed in quantitative yields. For alkyne complexes containing bulkier substituent(s) R1 = Me or Ph, R2 = SiMe3, and R1 = R2 = Ph or SiMe3, successful hydrogenation required the application of increased temperatures (70-80 °C) and prolonged reaction times, in particular for bis(trimethylsilyl)acetylene. Under these conditions, no transient 1 was detected during the formation of 2. The bulkier auxiliary ligands η5-C5Me4tBu and η5-C5Me4SiMe3 did not hinder the addition of dihydrogen to the corresponding titanocenes [(η5-C5Me4tBu)2Ti] and [(η5-C5Me4SiMe3)2Ti] yielding [(η5-C5Me4tBu)2TiH2] (3) and [(η5-C5Me4SiMe3)2TiH2] (4), respectively. In contrast to 1, the dihydride 4 did not decay with the formation of titanocene monohydride, but dissociated to titanocene upon dihydrogen removal. The monohydrides [(η5-C5Me4tBu)2TiH] (5) and [(η5-C5Me4SiMe3)2TiH] (6) were obtained by insertion of dihydrogen into the intramolecular titanium-methylene σ-bond in compounds [(η5-C5Me4tBu)(η5:η1-C5Me4CMe2CH2)Ti] and [(η5-C5Me4SiMe3)(η5:η1-C5Me4SiMe2CH2)Ti], respectively. The steric influence of the auxiliary ligands became clear from the nature of the products obtained by reacting 5 and 6 with butadiene. They appeared to be the exclusively σ-bonded η1-but-2-enyl titanocenes (7) and (8), instead of the common π-bonded derivatives formed for the sterically less congested titanocenes, including [Cp?2Ti(η3-(1-methylallyl))] (9). The molecular structure optimized by DFT for compound 1 acquired a distinctly lower total energy than the analogously optimized complex with a coordinated dihydrogen [Cp?2Ti(η2-H2)]. The stabilization energies of binding the hydride ligands to the bent titanocenes were estimated from counterpoise computations; they showed a decrease in the order 1 (-132.70 kJ mol-1), 3 (-121.11 kJ mol-1), and 4 (-112.35 kJ mol-1), in accordance with the more facile dihydrogen dissociation.
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Hoeg,Lusk
, p. 928 (1964)
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Development of Carbon-Neutral Cellulose-Supported Heterogeneous Palladium Catalysts for Chemoselective Hydrogenation
Yamada, Tsuyoshi,Teranishi, Wataru,Park, Kwihwan,Jiang, Jing,Tachikawa, Takumu,Furusato, Shinichi,Sajiki, Hironao
, p. 4052 - 4058 (2020)
Palladium catalysts immobilized on cellulose particles (Pd/CLP) and on a cellulose-monolith (Pd/CLM) were developed. These composites were applied as hydrogenation catalysts and their catalyst activities were evaluated. Although both catalysts catalyzed the deprotection of benzyloxycarbonyl-protected aromatic amines (Ar-N-Cbz) and aromatic benzyl esters (Ar-CO2Bn), only Pd/CLM could accomplish the hydrogenolysis of aliphatic-N-Cbz and aliphatic-CO2Bn protective groups. The difference in the physical structure of the cellulose supports induced unique chemoselectivity. Aliphatic-N-Cbz and aliphatic-CO2Bn groups were tolerated under the Pd/CLP-catalyzed hydrogenation conditions, while Ar-N-Cbz, Ar-CO2Bn, alkene, alkyne, azido and nitro groups could be smoothly reduced.
Synthesis and hydrogenation activity of iron dialkyl complexes with chiral bidentate phosphines
Hoyt, Jordan M.,Shevlin, Michael,Margulieux, Grant W.,Krska, Shane W.,Tudge, Matthew T.,Chirik, Paul J.
, p. 5781 - 5790 (2014)
The activity of bis(phosphine) iron dialkyl complexes for the asymmetric hydrogenation of alkenes has been evaluated. High-throughput experimentation was used to identify suitable iron-phosphine combinations using the displacement of pyridine from py2Fe(CH2SiMe3)2 for precatalyst formation. Preparative-scale synthesis of a family of bis(phosphine) iron dialkyl complexes was also achieved using both ligand substitution and salt metathesis methods. Each of the isolated organometallic iron complexes was established as a tetrahedral and hence high-spin ferrous compound, as determined by M?ssbauer spectroscopy, magnetic measurements, and, in many cases, X-ray diffraction. One example containing a Josiphos-type ligand, (SL-J212-1)Fe(CH2SiMe3)2, proved more active than other isolated iron dialkyl precatalysts. Filtration experiments and the lack of observed enantioselectivity support dissociation of the phosphine ligand upon activation with dihydrogen and formation of catalytically active heterogeneous iron. The larger six-membered chelate is believed to reduce the coordination affinity of the phosphine for the iron center, enabling metal particle formation.
Allenylsilanes fonctionnels II. Synthese par voie organoaluminique du 2-trimethylsilylbuta-2,3-dienal et application a la synthese d'alcools secondaires α-alleniques trimethylsilyles
Mesnard, Danielle,Miginiac, Leone
, p. 277 - 287 (1992)
The 2-trimethylsilyl-2,3-butadienal is easily prepared, in good yield, by the reaction at -80 deg C between triethylorthoformate and the organoaluminum compound prepared from Me3SiCC-CH2Br.The resulting conjugated aldehyde reacts readily with various organometallic compounds (containing Al, Mg, Zn) to produce alcohols resulting from an 1,2-addition only, but for the saturated or phenylic magnesium derivatives which also give products from 1,4-addition.
Silver-Catalyzed Decarboxylative Couplings of Acids and Anhydrides: An Entry to 1,2-Diketones and Aryl-Substituted Ethanes
Zou, Hua-Xu,Li, Yang,Yang, Yuan,Li, Jin-Heng,Xiang, Jiannan
, p. 1439 - 1443 (2018)
Silver-catalyzed oxidative decarboxylative couplings of carboxylic acids and anhydrides to produce 1,2-diketones and substituted ethanes were developed. This reaction allows the generation of acyl or alkyl radicals by decarboxylation of the corresponding α-keto acids, alkyl acids and anhydrides, which are sequentially coupled to efficiently construct a new C?C bond. This reaction represents a carboxylic acid decarboxylative alternative that employs a radical termination strategy. (Figure presented.).
On the Mechanism of Thermal Ring Expansion of 3,3-Dialkyloxindoles
McNab, Hamish
, p. 543 - 545 (1990)
13C Labelling experiments show that the title reaction takes place by a free radical mechanism which involves (i) homolysis of the C(3)-alkyl bond, (ii) rearrangement of the resulting 3-indolyl radical to a 3-indolylmethyl radical , (iii) ring expansion by competitive neophyl rearrangement or attack at the carbonyl position, and (iv) aromatisation by loss of a hydrogen atom.
Synthesis and catalytic hydrogenation reactivity of a chromium catecholate porous organic polymer
Camacho-Bunquin, Jeffrey,Siladke, Nathan A.,Zhang, Guanghui,Niklas, Jens,Poluektov, Oleg G.,Nguyen, Sonbinh T.,Miller, Jeffrey T.,Hock, Adam S.
, p. 947 - 952 (2015)
A single-site chromium catecholate POP (catPOP A2B1) was synthesized and characterized via AT-IR, XAS, and EPR spectroscopy. The well-defined, four-coordinate, 11-electron Cr(III) centers bound to catecholate POP were demonstrated to be active hydrogenation catalysts for nonpolar unsaturated organic substrates under mild conditions (5 mol % of Cr, 200 psi of H2, 60 °C). This material constitutes the first example of a well-defined, supported organometallic chromium hydrogenation precatalyst.
Heavy cation effect on intersystem crossing between triplet and singlet phenylacyl and benzyl geminate radical pairs within zeolites
Warrier,Turro,Ramamurthy
, p. 7163 - 7167 (2000)
The difference in product selectivity observed between dibenzyl ketones and naphthyl esters in zeolites is due to the difference in spin of the radical pairs formed from these precursors. Heavy cations present in zeolites can enhance intersystem crossing between triplet and singlet geminate radical pairs. (C) 2000 Elsevier Science Ltd.
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Breuer,Broster
, p. 2193 (1972)
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Activation of heteroallenes by coordinatively unsaturated nickel(II) alkyl complexes supported by the hydrotris(3-phenyl-5-methyl)pyrazolyl borate (TpPh,Me) ligand
Abubekerov, Mark,Eymann, Léonard Y. M.,Gianetti, Thomas L.,Arnold, John
, p. 14581 - 14590 (2016)
Activation of sulfur containing heteroallenes by nickel(ii) alkyl complexes supported by the bulky hydrotris(3-phenyl-5-methylpyrazolyl)borate (TpPh,Me) ligand is described. Exposure of TpPh,MeNiCH2Ph (1a) and TpPh,MeNiCH2Si(CH3)3 (1b) to CS2 resulted in formation of the insertion products TpPh,MeNi(η2-CS2)CH2Ph (2a) and TpPh,MeNi(η2-CS2)CH2Si(CH3)3 (2b) in moderate yields. Reaction of 1a and MeNCS produced two species in a 1:1 ratio, identified as TpPh,MeNi(η2-MeNC)CH2Ph (3) and TpPh,MeNi(η2-MeNCS)SCH2Ph (4). Isolation of the unexpected insertion product (3) prompted an investigation into the activity of 1a-b in the presence of isocyanides (i.e.tBuNC), which resulted in isolation of TpPh,MeNi(η2-tBuNC)CH2Ph (5a) and TpPh,MeNi(η2-tBuNC)CH2Si(CH3)3 (5b). Similarly, reaction of 1a with OCS led to the isolation of a rare example of a Ni(i) carbonyl species TpPh,MeNiCO (6). Alternatively, complex 6 was also formed by exposure of 1a-b to an atmosphere of CO. Isolation of the intermediate species (TpPh,MeNi(η2-CO)CH2TMS (7b) and TpPh,MeNi(CO)(C(O)R, (8a-b) with R = Ph, TMS)) shed light on the formation of such species.
HIGH ACTIVITY OF MoO3-SnO2 FOR HYDROCRACKING OF DIPHENYL ETHER AND DIPHENYLMETHANE
Stenberg, Virgil I.,Srinivas, V. R.,Tanabe, Kozo,Jin, Tuo,Hattori, Hideshi
, p. 1547 - 1550 (1982)
Of four newly synthesized catalysts designed for coal liquefaction, MoO3-SnO2 was superior for use with diphenyl ether and diphenylmethane with either H2 or CO + H2O.This agrees with the results of using these catalysts with a sub-bitumenous coal.Carbon monoxide and H2O is superior to H2 for ether cleavage, whereas H2 is better for hydrocarbon cleavage.
Kinetics of the thermal decomposition reaction of diethylketone cyclic triperoxide in acetone-toluene and acetone-1 -propanol binary solvent mixtures
Iglesias, Mariangeles,Eyler, Nora,Canizo, Adriana
, p. 96 - 100 (2009)
The thermal decomposition reaction of diethylketone triperoxide (DEKT) ca. 0.02 M was studied in binary mixtures of acetone-toluene and acetone-1 -propanol at 150°C. Products of DEKT thermolysis in solution, detected by GC analysis, were diethylketone, bi
Transfer semihydrogenation of alkynes catalyzed by a zero-valent palladium N-heterocyclic carbene complex
Hauwert, Peter,Maestri, Giovanni,Sprengers, Jeroen W.,Catellani, Marta,Elsevier, Cornelis J.
, p. 3223 - 3226 (2008)
(Chemical Equation Presented) Beyond Lindlar and without hydrogen: Transfer hydrogenation of internal alkynes catalyzed by a palladium(0) catalyst containing an N-heterocyclic carbene ligand gives Z alkenes without over-reduction to alkanes (see scheme). Contrary to most transfer hydrogenations, ketones are not reduced. As such, this is the first catalyst that shows excellent stereo- and chemo-selectivity for the semihydrogenation of alkynes without the need for hydrogen gas.
Synthesis and structural characterization of a layer-segregated platinum-ruthenium cluster complex that exhibits selective coordination and a high activity for the catalytic hydrogenation of diphenylacetylene
Adams, Richard D.,Li, Zhaoyang,Swepston, Paul,Wu, Wengan,Yamamoto, John
, p. 10657 - 10658 (1992)
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Highly selective catalysts for liquid-phase hydrogenation of substituted alkynes based on Pd—Cu bimetallic nanoparticles
Mashkovsky,Markov,Bragina,Tkachenko,Yakushev,Kozitsyna, N. Yu.,Vargaftik,Stakheev, A. Yu.
, p. 425 - 431 (2016)
Catalytic properties of Pd—Cu bimetallic catalysts supported on SiO2 and Al2O3 were studied in a model reaction of selective hydrogenation of diphenylacetylene. Application of PdCu2(AcO)6 heterobimetallic acetate complex as a precursor made it possible to obtain homogeneous Pd—Cu bimetallic nanoparticles. This result was supported by the data of IR spectroscopy of adsorbed CO. The Pd-Cu catalysts showed considerably higher selectivity than monometallic samples. Moreover, the introduction of copper decreases the hydrogenation rate of diphenylethylene (DPE) to diphenylethane. As a result, the maximum yield of the target product, DPE, increased from 78 to 93% in the presence of Pd—Cu catalysts.
Formation of Alcohols from Alkenes with TiCl4-NaBH4
Kano, Shinzo,Tanaka, Yasuyuki,Hibino, Satoshi
, p. 414 - 415 (1980)
The reaction of alkenes with TiCl4-NaBH4 in 1,2-dimethoxyethane afforded alcohols, the hydroxy group of which was introduced in an anti-Markovnikov direction.
SIZE, SHAPE, AND SITE SELECTIVITIES IN THE PHOTOCHEMICAL REACTIONS OF MOLECULES ADSORBED ON PENTASIL ZEOLITES. EFFECTS OF COADSORBED WATER
Turro, Nicholas J.,Cheng, Chen-Chih,Abrams, Lloyd,Corbin, David R.
, p. 2449 - 2456 (1987)
The photochemistry of methylbenzyl benzyl ketones (ACOB) in the presence of pentasil zeolites follows strikingly different pathways due to the location of the adsorbed ketone.The product distribution, in terms of the cage effect (efficiency of geminate radical combination), demonstrates the effects of sorption and diffusion on the radical species produced by photolysis. p-ACOB is readily adsorbed within the pentasil framework and produces p-AB as the primary product.In contrast, the photolysis product distributions of o-ACOB can be dramatically varied depending upon the extent of its adsorption into the framework.By addition of a nonreactive titrant, such as water, after the ketone adsorption, the photolysis product distributions can be systematically varied depending upon the aluminum content of the framework.The observed results are completely described by considerations of (a) the size and shape sorption of the pentasil zeolites, (b) the sorption of water by the hydrophilic sites of the pentasil zeolites (which depend upon the framework aluminum content), and (c) the hydrophobic characteristics of the pentasil channels which do not contain framework aluminum.
Catalytic Reduction of Diphenylacetylene by Zinc over Palladium-Carbon Using Viologens as Electron Mediators
Shosenji, Hideto,Nakano, Yasuhiro,Yamada, Kimiho
, p. 1033 - 1036 (1988)
Diphenylacetylene was reduced over palladium-carbon in methanol-water mixture in presence of zinc using N,N'-dialkyl-4,4'-bipyridinium ions (viologens) as mediators giving cis-stilbene as the major product and bibenzyl as the minor one.The reaction involved the direct contact of zinc with the catalyst.
Photochemistry of 2,5,7,7-Tetraphenyl-7-boratabicyclohepta-2,4-diene (a Boratanorcaradiene Anion): No Evidence for Diphenylborene Anion
Boyatzis, Stamatis,Wilkey, John D.,Schuster, Gary B.
, p. 4537 - 4544 (1990)
Irradiation of 2,5,7,7-tetraphenyl-7-boratabicyclohepta-2,4-diene anion (1, a boratanorcaradiene, as its potassium or tetramethylammonium salt) with UV light leads to formation of p-terphenyl in high yield.This observation led us to consider the possibility that diphenylborene anion (Ph2B-, an analogue of diphenylcarbene) might also be formed in this reaction.We designed and carried out a series of spectroscopic and chemical experiments to detect and characterize the borene.None of these experiments provides evidence for the formation of diphenylborene from this reaction.We suggest that the formation of p-terphenyl from the photolysis of 1 is initiated by an electron-transfer (photoionization) process.We also reexamined experiments reported earlier that were claimed to show that diphenylborene is formed from the irraditation or overirradiation of tetraphenylborate.Each of these experiments is ambiguous and cannot be relied upon to demonstrate the formation of the borene by this route.
Cobalt-Catalyzed Csp3?Csp3Homocoupling
Cai, Yingxiao,Qian, Xin,Gosmini, Corinne
, p. 2427 - 2430 (2016)
An efficient and easy method for Csp3?Csp3homocoupling was developed using cobalt bromide as catalyst. A series of functionalized alkyl bromides and alkyl chlorides were coupled in high yields under mild conditions. This reaction seems to involve a radical intermediate. (Figure presented.).
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Gardner,Borgstrom
, p. 3376 (1929)
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6,12-Diphenyldibenzo[b,f][1,5]diazocine as an electron-capture agent: Efficient mechanistic probe for SET processes and reagent for the oxidative dimerization of benzylic organometallics
Eisch, John J.,Yu, Kun,Rheingold, Arnold L.
, p. 3165 - 3171 (2012)
In the present study, 6,12-diphenyldibenzo[b,f][1,5]diazocine, which X-ray diffraction measurements have now shown to possess a tub-shaped, eight-membered central ring, has been treated with sodium or lithium metal at 25 °C in THF, in an attempt to form the planar, Hueckel-aromatic dianion by the addition of two electrons to the central diazocine. Hydrolysis of such an aromatic dianion should have led to the isomeric 5,12- or 5,6-dihydro derivative of the original diazocine. In actuality, the only product obtained quantitatively upon hydrolytic workup was the interesting quadricyclic transannular reduction product, 4b,9b-diphenyl-4b,5,9b,10-tetrahydroindolo[3,2-b]indole, whose 3D structure has now been confirmed by X-ray crystallography and 13C NMR spectroscopy. Preferential SET transannular reduction of the diazocine to yield the quadricyclic indolo[3,2-b]indole dianion, rather than the planar, Hueckel-aromatic anion, is ascribed to the transannular electronic stabilization operative in the tub-shaped diazocine radical-anion. The quantitative generation of the indolo[3,2-b]indole dianion can be employed for the oxidative dimerization of the organic groups in benzylic lithium reagents. Thus treating one equivalent of the diazocine with two equivalents of benzyllithium, benzhydryllithium, or trityllithium yields quantitatively bibenzyl, 1,1,2,2-tetraphenylethane, or (4-benzhydrylphenyl)triphenylmethane, respectively. This oxidative dimerization is potentially of practical preparative scope, since the hydrolysis byproduct, the indolo[3,2-b]indole, is conveniently reconverted into the starting diazocine reagent by oxidation with chromium trioxide in acetic acid. The formation of the indolo[3,2-b]indole as a byproduct in the carbometalation of the diazocine by various RLi and Grignard reagents offers a clue as to the SET mechanism of carbometalation. Copyright
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West,Jones
, p. 2656 (1968)
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Heterobimetallic Pd/Mn and Pd/Co complexes as efficient and stereoselective catalysts for sequential Cu-free Sonogashira coupling–alkyne semi-hydrogenation reactions
Baweja, Saral,Clauss, Reike,Gelman, Dmitri,Hey-Hawkins, Evamarie
, p. 1344 - 1356 (2022/02/03)
A series of heterobimetallic PdII/MII complexes (MII = Mn, Co) were synthesised and tested as precatalysts for sequential Sonogashira coupling–alkyne semi-hydrogenation reactions to form Z-aryl alkenes. The carbometalated heterobimetallic PdII/CoII complex CoPdL3′ demonstrated an apparent cooperative effect compared to the corresponding monometallic counterparts. This compound was identified as a potent single-molecule catalyst for the one-pot Cu-free Sonogashira coupling of aryl bromides with terminal alkynes followed by chemo- and stereoselective semi-hydrogenation of the alkyne intermediate using NH3·BH3 as a hydrogen source. Furthermore, different aromatic substrates have been tested to show the generality of the reaction for the synthesis of Z-alkenes, including biologically active combretastatin A-4. In addition, the homogeneous nature of the catalytically active species was demonstrated.
Reductive C(sp3)-C(sp3) homo-coupling of benzyl or allyl halides with H2using a water-soluble electron storage catalyst
Futakuchi, Sayaka,Miyazawa, Keishi,Nakai, Hidetaka,Ogo, Seiji,Shimauchi, Daiki,Takahashi, Yukina,Yatabe, Takeshi,Yoon, Ki-Seok
, p. 39450 - 39454 (2021/12/27)
This paper reports the first example of a reductive C(sp3)-C(sp3) homo-coupling of benzyl/allyl halides in aqueous solution by using H2as an electron source {turnover numbers (TONs) = 0.5-2.3 for 12 h}. This homo-coupling reaction, promoted by visible light, is catalysed by a water-soluble electron storage catalyst (ESC). The reaction mechanism, and four requirements to make it possible, are also described.
Reactions of benzyltriphenylphosphonium salts under photoredox catalysis
Boldt, Andrew M.,Dickinson, Sidney I.,Ramirez, Jonathan R.,Benz-Weeden, Anna M.,Wilson, David S.,Stevenson, Susan M.
, p. 7810 - 7815 (2021/09/28)
The development of benzyltriphenylphosphonium salts as alkyl radical precursors using photoredox catalysis is described. Depending on substituents, the benzylic radicals may couple to form C-C bonds or abstract a hydrogen atom to form C-H bonds. A natural product, brittonin A, was also synthesized using this method.
