- Copper-catalyzed semihydrogenation of alkynes to Z -alkenes
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Copper-catalyzed semihydrogenation of internal alkynes has been developed. The reaction proceeds under an atmosphere of hydrogen (5 atm) at 100 °C in the presence of a readily available [(PPh3)CuCl]4 catalyst to give various Z-alkenes stereoselectively.
- Semba, Kazuhiko,Kameyama, Ryohei,Nakao, Yoshiaki
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- Isolated Organometallic Nickel(III) and Nickel(IV) Complexes Relevant to Carbon-Carbon Bond Formation Reactions
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Nickel-catalyzed cross-coupling reactions are experiencing a dramatic resurgence in recent years given their ability to employ a wider range of electrophiles as well as promote stereospecific or stereoselective transformations. In contrast to the extensively studied Pd catalysts that generally employ diamagnetic intermediates, Ni systems can more easily access various oxidation states including odd-electron configurations. For example, organometallic NiIII intermediates with aryl and/or alkyl ligands are commonly proposed as the active intermediates in cross-coupling reactions. Herein, we report the first isolated NiIII-dialkyl complex and show that this species is involved in stoichiometric and catalytic C-C bond formation reactions. Interestingly, the rate of C-C bond formation from a NiIII center is enhanced in the presence of an oxidant, suggesting the involvement of transient NiIV species. Indeed, such a NiIV species was observed and characterized spectroscopically for a nickelacycle system. Overall, these studies suggest that both NiIII and NiIV species could play an important role in a range of Ni-catalyzed cross-coupling reactions, especially those involving alkyl substrates.
- Schultz, Jason W.,Fuchigami, Kei,Zheng, Bo,Rath, Nigam P.,Mirica, Liviu M.
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- Electrolytically Induced Allene-Alkyne Isomerization
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Preparative-scale electrolyses at mercury cathodes in dimethylformamide containing tetra-n-butylammonium perchlorate have revealed that 1-phenyl-1,2-hexadiene exhibits no evidence of isomerization to form 1-phenyl-1-hexyne via an electrolytically induced, base-catalyzed rearrangement; similarly, 1-phenyl-1,2-butadiene exhibits only a slight tendency (1-2percent) to form 1-phenyl-1-butyne.In contrast, voltammetric and electrolytic experiments demonstrate that isomerization of 1-phenyl-1-butyne, 1-phenyl-1-pentyne, and 1-phenyl-1-hexyne to the corresponding allenes occurs muchmore readily.Observations from several investigations show that the extent of allene-to-alkyne rearrangement increases from 1-phenyl-1,2-hexadiene to 1-phenyl-1,2-butadiene to phenylpropadiene, whereas the reverse alkyne-to-allene isomerization decreases in significance from 1-phenyl-1-hexyne to 1-phenyl-1-pentyne to 1-phenyl-1-butyne to 1-phenyl-1-propyne.Steric and electronic factors, which affect protonation of the conjugate bases of the various starting materials at acrbons 1 and 3, can be invoked to explain these trends.
- Stemple, Joseph Z.,Peters, Dennis G.
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- Efficient synthesis of amylbenzenes over zeolite catalysts
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The liquid-phase heterogeneous alkylation of benzene with 2-methyl-2-butene takes place actively and selectively over large-pore zeolite catalysts, which implies an environmentally friendly route for the synthesis of fert-amylbenzene. Copyright
- Zhang, Huanyan,Liu, Yueming,Wu, Haihong,Jiang, Yongwen,He, Mingyuan,Wu, Peng
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- Deoxygenation of Unhindered Alcohols via Reductive Dealkylation of Derived Phosphate Esters
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Primary alcohols can be deoxygenated cleanly and in yields of 60-95% by reduction of derived diphenyl phosphate esters with lithium triethylborohydride in tetrahydrofuran at room temperature. Selective deoxygenation of a primary alcohol in the presence of a secondary alcohol was demonstrated. The two-step process can be performed in one pot, making it simple and convenient.
- Chowdhury, Sarwat,Standaert, Robert F.
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- Relevance of Single-Transmetalated Resting States in Iron-Mediated Cross-Couplings: Unexpected Role of σ-Donating Additives
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Control of the transmetalation degree of organoiron(II) species is a critical parameter in numerous Fe-catalyzed cross-couplings to ensure the success of the process. In this report, we however demonstrate that the selective formation of a monotransmetalated FeII species during the catalytic regime counterintuitively does not alone ensure an efficient suppression of the nucleophile homocoupling side reaction. It is conversely shown that a fine control of the transmetalation degree of the transient FeIII intermediates obtained after the activation of alkyl electrophiles by a single-electron transfer (SET), achievable using σ-donating additives, accounts for the selectivity of the cross-coupling pathway. This report shows for the first time that both coordination spheres of FeII resting states and FeIII short-lived intermediates must be efficiently tuned during the catalytic regime to ensure high coupling selectivities.
- Rousseau, Lidie,Touati, Nadia,Binet, Laurent,Thuéry, Pierre,Lefèvre, Guillaume
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- N-Hexane activation over zeolites: Aromatic alkylation to 1-phenylhexane
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Terminal 1-phenylhexane was observed during alkylation of benzene with n-hexane over 10-membered ring zeolites at moderate temperature, whereas it was not observed when 1-hexene was the reactant. The Royal Society of Chemistry 2010.
- Danilina, Nadiya,Payrer, Elisabeth L.,Van Bokhoven, Jeroen A.
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- Nanocage catalysts - Rhodium nanoclusters encapsulated with dendrimers as accessible and stable catalysts for olefin and nitroarene hydrogenations
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The phenylazomethine dendrimer generation 4 (TPP-DPA G4) and polyamidoamine dendrimer (PAMAM G4-OH) encapsulating rhodium nanocluster were found to be highly effective for olefin and nitroarene hydrogenations, affording high TOF (up to 17520 h-1); the important feature of the nanocage catalyst is that substrates can pass through the branches of the protecting groups of nanoclusters without releasing nanoclusters from the dendrimer. The Royal Society of Chemistry.
- Nakamula, Ikuse,Yamanoi, Yoshinori,Yonezawa, Tetsu,Imaoka, Takane,Yamamoto, Kimihisa,Nishihara, Hiroshi
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- Arylation of hydrocarbons enabled by organosilicon reagents and weakly coordinating anions
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Over the past 80 years, phenyl cation intermediates have been implicated in a variety of C-H arylation reactions. Although these examples have inspired several theoretical and mechanistic studies, aryl cation equivalents have received limited attention in organic methodology. Their high-energy, promiscuous reactivity profiles have hampered applications in selective intermolecular processes. We report a reaction design that overcomes these challenges. Specifically, we found that b-silicon-stabilized aryl cation equivalents, generated via silylium-mediated fluoride activation, undergo insertion into sp3 and sp2 C-H bonds. This reaction manifold provides a framework for the catalytic arylation of hydrocarbons, including simple alkanes such as methane. This process uses low loadings of Earth-abundant initiators (1 to 5 mole percent) and occurs under mild conditions (30° to 100°C).
- Shao, Brian,Bagdasarian, Alex L.,Popov, Stasik,Nelson, Hosea M.
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- Reactivity of mixed organozinc and mixed organocopper reagents. Part 4: A kinetic study of group transfer selectivity in C-C coupling of mixed diorganocuprates
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The competitive rate data and Taft relationships for the coupling of bromomagnesium n-butyl (substituted phenyl) cuprates with alkyl bromides show that selective n-butyl transfer can be explained by an oxidative addition mechanism. Taft reaction constants
- Erdik, Ender,Oezkan, Duygu
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- Dipyrrolidinomethylaminophosphoric acid triamide (DPMPA) as an activator for the samarium diiodide-mediated reduction of alkyl and aryl halides
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The use of the conjugate base of dipyrrolidinomethylaminophosphoric triamide (DPMPA-) as an activator of samarium diiodide is reported. This phosphoramidate has been shown to be a very potent ligand, allowing for the efficient, low-temperature reduction of alkyl and aryl chlorides. Reductive cyclizations of haloalkenylnaphthalenes are also reported.
- McDonald, Chriss E.,Ramsey, Jeremy R.,Sampsell, David G.,Anderson, Laura A.,Krebs, Jordan E.,Smith, Samantha N.
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- Hydrodecyanation of Secondary Alkyl Nitriles and Malononitriles to Alkanes using DiMeImd-BH3
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The decyanation of secondary aliphatic nitriles and the 2-fold decyanation of malononitriles leading to alkanes in the presence of 1,3-dimethylimidazol-2-ylidene borane (diMeImd-BH3) are reported. These reactions proceed via a radical mechanism that involves the addition of a borane radical to the nitrile to form an iminyl radical, followed by cleavage of a carbon-carbon bond. Theoretical calculations suggest that the β-cleavage of these iminyl radicals, which affords NHC-BH2CN and the corresponding alkyl radicals, is the rate-determining step in this reaction.
- Kawamoto, Takuji,Oritani, Kyohei,Kawabata, Atsushi,Morioka, Tsubasa,Matsubara, Hiroshi,Kamimura, Akio
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- Organolithium additions to styrene are synthetically viable
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In diethyl ether at -78 to -25°C, styrene undergoes efficient addition reactions with a range of alkyllithium reagents, and the intermediate benzyllithiums can be trapped (e.g. with carbon dioxide and chlorotrimethylsilane); two aryl-substituted styrenes are shown to react in a similar manner.
- Wei, Xudong,Taylor, Richard J. K.
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- Preparation of E-alkenes using lithium and 1,3-diaminopropane
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A new selective reducing system, lithium in 1,3-diaminopropane, is described, which enables the preparation of E-olefins from acetylenes in high purity.
- Kovarova,Streinz
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- Regioselective Hydroalkylation of Vinylarenes by Cooperative Cu and Ni Catalysis
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Disclosed here is a dual copper and nickel catalytic system with a silyl hydride source for promoting the linear selective hydroalkylation of vinylarenes. This carbon–carbon bond-forming protocol is applied to couple a variety of functionalized vinylarenes with alkyl halides applying a nickel(II) NNN pincer complex in the presence of an NHC-ligated copper catalyst. This combination allows for a 1 mol % loading of the nickel catalyst leading to turnover numbers of up to 72. Over 40 examples are presented, including applications for pharmaceutical diversification. Labeling experiments demonstrated the regioselectivity of the reaction and revealed that the copper catalyst plays a crucial role in enhancing the rate for formation of the reactive linear alkyl nickel complex. Overall, the presented work provides a complimentary approach for hydroalkylation reactions, whilst providing a preliminary mechanistic understanding of the cooperativity between the copper and nickel complexes.
- Ravn, Anne K.,Johansen, Martin B.,Skrydstrup, Troels
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supporting information
(2021/12/14)
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- Photocatalytic transfer hydrogenolysis of aromatic ketones using alcohols
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A mild method of photocatalytic deoxygenation of aromatic ketones to alkyl arenes was developed, which utilized alcohols as green hydrogen donors. No hydrogen evolution during this transformation suggested a mechanism of direct hydrogen transfer from alcohols. Control experiments with additives indicated the role of acid in transfer hydrogenolysis, and catalyst characterization confirmed a larger number of Lewis acidic sites on the optimal Pd/TiO2 photocatalyst. Hence, a combination of hydrogen transfer sites and acidic sites may be responsible for efficient deoxygenation without additives. The photocatalyst showed reusability and achieved selective reduction in a variety of aromatic ketones.
- Gao, Zhuyan,Han, Jianyu,Hong, Feng,Lei, Lijun,Li, Hongji,Liu, Huifang,Luo, Nengchao,Wang, Feng
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p. 3802 - 3808
(2020/07/09)
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- (1-(substituted phenyl)acenaphthylene)-bis(3,5-bis(trifluoromethyl))phenylphosphine compound and preparation method thereof
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The invention relates to a large-steric-hindrance electron-deficient organic phosphine ligand compound, and more specifically relates to a (1-(substituted phenyl)acenaphthylene)-bis(3,5-bis(trifluoromethyl))phenylphosphine ligand compound having a structure represented by any one of the following formulas, and a synthetic method thereof. The large-steric-hindrance electron-deficient organic phosphine ligand compound synthesized by taking acenaphthylene as a skeleton has multiple modifiable sites, is rich in structure, can stably exist in air, is easily available in synthetic raw materials andsimple in synthetic method, and can be used as an important ligand in the field of palladium catalysts.
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Paragraph 0197-0200
(2019/12/02)
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- Iron-catalyzed AlkylAlkyl negishi coupling of organoaluminum reagents
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The first iron-catalyzed cross-coupling reaction of alkyl halides with alkylaluminum reagents (alkylalkyl Negishi coupling) is developed using an iron/bisphosphine catalyst system. The reaction shows high functional group tolerance: various primary alkyl halides possessing a non-protected indole, carboxyl, or hydroxy group are coupled with primary alkylaluminum reagents in good yields. Potassium fluoride plays a key role to promote the reaction by generating an aluminate species, which facilitates the transmetalation between the organoaluminum and the iron catalyst.
- Agata, Ryosuke,Kawamura, Shintaro,Isozaki, Katsuhiro,Nakamura, Masaharu
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supporting information
p. 238 - 241
(2019/03/13)
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- Alkyl Carbagermatranes Enable Practical Palladium-Catalyzed sp2-sp3 Cross-Coupling
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Pd-catalyzed cross-coupling reactions have achieved tremendous accomplishments in the past decades. However, C(sp3)-hybridized nucleophiles generally remain as challenging coupling partners due to their sluggish transmetalation compared to the C(sp2)-hybridized counterparts. While a single-electron-transfer-based strategy using C(sp3)-hybridized nucleophiles had made significant progress recently, fewer breakthroughs have been made concerning the traditional two-electron mechanism involving C(sp3)-hybridized nucleophiles. In this report, we present a series of unique alkyl carbagermatranes that were proven to be highly reactive in cross-coupling reactions with our newly developed electron-deficient phosphine ligands. Generally, secondary alkyl carbagermatranes show slightly lower, yet comparable activity to its Sn analogue. Meanwhile, primary alkyl carbagermatranes exhibit high activity, and they were also proved stable enough to be compatible with various reactions. Chiral secondary benzyl carbagermatrane gave the coupling product under base/additive-free conditions with its configuration fully inversed, suggesting that transmetalation was carried out in an "SE2(open) Inv" pathway, which is consistent with Hiyama's previous observation. Notably, the cross-coupling of primary alkyl carbagermatranes could be performed under base/additive-free conditions with excellent functional group tolerance and therefore may have potentially important applications such as stapled peptide synthesis.
- Xu, Meng-Yu,Jiang, Wei-Tao,Li, Ying,Xu, Qing-Hao,Zhou, Qiao-Lan,Yang, Shuo,Xiao, Bin
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supporting information
p. 7582 - 7588
(2019/05/16)
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- Method for preparing large-steric-hindrance electron-deficient organic phosphine ligand compound
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The present invention relates to a novel method for preparing a large-steric-hindrance electron-deficient organic phosphine ligand compound represented by any one of the following formulae, wherein the phosphine is introduced first, the method comprises the following steps: by taking phenylacetylene as a raw material, performing a coupling reaction, and efficiently obtaining the required (1, 1-(dimethyl)-2-substituted phenyl indene (3, 5-bis (trifluoromethyl)) phenyl phosphine (5) by taking phenylacetylene as a raw material through intermediates including 2-methyl-4-phenyl-3-butyne-2-ol, 2, 3-diiodo-1, 1-dimethyl-indene and (1-iodine) indene)-bis (3-bis (3-bis (trifluoromethyl) phenyl phosphine). The novel large-steric-hindrance electron-deficient organic phosphine ligand compound is obtained through a brand-new reaction process. The organic phosphine ligand compound obtained by the invention has the advantages of stable property, stable existence in air, multiple modifiable sites, rich synthetic structure, easily available raw materials and simple synthetic method, and can be used as an important ligand in the field of palladium catalysts.
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Paragraph 0113-0115
(2019/12/02)
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- Bis(bipyridine) ruthenium(ii) bis(phosphido) metalloligand: Synthesis of heterometallic complexes and application to catalytic (E)-selective alkyne semi-hydrogenation
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The first phosphido derivative of the bis(bipyridine) ruthenium(ii) fragment, cis-[(bpy)2Ru(PPh2)2] ([RuP2]), has been developed and applied as a P-donor metalloligand to form new Ru-Rh, Ru-Ir and Ru2Cu2 heterometallic complexes. The Ru-Ir hydride complex [([RuP2])IrH(NCMe)3][BF4]2 exhibits significant catalytic activity for (E)-selective semi-hydrogenation of alkynes.
- Takemoto, Shin,Kitamura, Manami,Saruwatari, Shuhei,Isono, Atsutaka,Takada, Yoko,Nishimori, Rie,Tsujiwaki, Mina,Sakaue, Naoki,Matsuzaka, Hiroyuki
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supporting information
p. 1161 - 1165
(2019/01/28)
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- Transfer Hydrogenation of Alkenes Using Ethanol Catalyzed by a NCP Pincer Iridium Complex: Scope and Mechanism
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The first general catalytic approach to effecting transfer hydrogenation (TH) of unactivated alkenes using ethanol as the hydrogen source is described. A new NCP-type pincer iridium complex (BQ-NCOP)IrHCl containing a rigid benzoquinoline backbone has been developed for efficient, mild TH of unactivated C-C multiple bonds with ethanol, forming ethyl acetate as the sole byproduct. A wide variety of alkenes, including multisubstituted alkyl alkenes, aryl alkenes, and heteroatom-substituted alkenes, as well as O- or N-containing heteroarenes and internal alkynes, are suitable substrates. Importantly, the (BQ-NCOP)Ir/EtOH system exhibits high chemoselectivity for alkene hydrogenation in the presence of reactive functional groups, such as ketones and carboxylic acids. Furthermore, the reaction with C2D5OD provides a convenient route to deuterium-labeled compounds. Detailed kinetic and mechanistic studies have revealed that monosubstituted alkenes (e.g., 1-octene, styrene) and multisubstituted alkenes (e.g., cyclooctene (COE)) exhibit fundamental mechanistic difference. The OH group of ethanol displays a normal kinetic isotope effect (KIE) in the reaction of styrene, but a substantial inverse KIE in the case of COE. The catalysis of styrene or 1-octene with relatively strong binding affinity to the Ir(I) center has (BQ-NCOP)IrI(alkene) adduct as an off-cycle catalyst resting state, and the rate law shows a positive order in EtOH, inverse first-order in styrene, and first-order in the catalyst. In contrast, the catalysis of COE has an off-cycle catalyst resting state of (BQ-NCOP)IrIII(H)[O(Et)···HO(Et)···HOEt] that features a six-membered iridacycle consisting of two hydrogen-bonds between one EtO ligand and two EtOH molecules, one of which is coordinated to the Ir(III) center. The rate law shows a negative order in EtOH, zeroth-order in COE, and first-order in the catalyst. The observed inverse KIE corresponds to an inverse equilibrium isotope effect for the pre-equilibrium formation of (BQ-NCOP)IrIII(H)(OEt) from the catalyst resting state via ethanol dissociation. Regardless of the substrate, ethanol dehydrogenation is the slow segment of the catalytic cycle, while alkene hydrogenation occurs readily following the rate-determining step, that is, β-hydride elimination of (BQ-NCOP)Ir(H)(OEt) to form (BQ-NCOP)Ir(H)2 and acetaldehyde. The latter is effectively converted to innocent ethyl acetate under the catalytic conditions, thus avoiding the catalyst poisoning via iridium-mediated decarbonylation of acetaldehyde.
- Wang, Yulei,Huang, Zhidao,Leng, Xuebing,Zhu, Huping,Liu, Guixia,Huang, Zheng
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supporting information
p. 4417 - 4429
(2018/04/05)
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- An N-heterocyclic carbene ligand promotes highly selective alkyne semihydrogenation with copper nanoparticles supported on passivated silica
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We report a surface organometallic route that generates copper nanoparticles (NPs) on a silica support while simultaneously passivating the silica surface with trimethylsiloxy groups. The material is active for the catalytic semihydrogenation of phenylalkyl-, dialkyl- and diaryl-alkynes and displays high chemo- and stereoselectivity at full alkyne conversion to corresponding (Z)-olefins in the presence of an N-heterocyclic carbene (NHC) ligand. Solid-state NMR spectroscopy using the NHC ligand 13C-labeled at the carbenic carbon reveals a genuine coordination of the carbene to Cu NPs. The presence of distinct Cu surface environments and the coordination of the NHC to specific Cu sites likely account for the increased selectivity.
- Kaeffer, Nicolas,Liu, Hsueh-Ju,Lo, Hung-Kun,Fedorov, Alexey,Copéret, Christophe
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p. 5366 - 5371
(2018/06/27)
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- Reactivity of the diphosphinodithio ligated nickel(0) complex toward alkyl halides and resultant nickel(i) and nickel(ii)-alkyl complexes
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Diphosphinodithio ligated complexes of nickel(0), nickel(i) and nickel(ii)-alkyl with a reactivity relevant to the C-C bond formation were described. Stoichiometric reactions of the nickel(0) complex, [(P2S2)Ni] ([1]0, P2S2 = (Ph2PC6H4CH2S)2(C2H4)), with alkyl halides (RX) such as C6H5CH2Br, C2H3CH2Br, C2H5I and (CH3)2CHI were investigated, from which the products were found to be highly dependent on the nature of RX used. Oxidative addition of C2H3CH2Br to [1]0 provides the stable Ni(ii)-alkyl complexes [1-allyl]+. The reaction of [1]0 with C6H5CH2Br proceeds through a radical pathway resulting in the formation of the nickel(i) complex [1]+ and an organic homo-coupled product 1,2-diphenylethane. Oxidative addition of C2H5I or (CH3)2CHI to [1]0 can be achieved but it competes with the halogen atom abstraction reaction as found for C6H5CH2Br. [1]0 was shown to be an active catalyst for the coupling reactions of primary halides and alkyl Grignard reagents.
- Zhang, Ailing,Wang, Congxiao,Lai, Xiaoyu,Zhai, Xiaofang,Pang, Maofu,Tung, Chen-Ho,Wang, Wenguang
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supporting information
p. 15757 - 15764
(2018/11/23)
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- Cross-coupling reaction of alkyl halides with alkyl grignard reagents catalyzed by cp-iron complexes in the presence of 1,3-butadiene
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Iron-catalyzed cross-coupling reaction of alkyl halides with alkyl Grignard reagents by the combined use of cyclopentadienyl ligand and 1,3-butadiene additive is described. The reaction smoothly proceeds at room temperature using unactivated alkyl bromides and fluorides via non-radical mechanism, which is in sharp contrast with hitherto known Fe-catalyzed cross-coupling reactions of alkyl halides.
- Iwasaki, Takanori,Shimizu, Ryohei,Imanishi, Reiko,Kuniyasu, Hitoshi,Kambe, Nobuaki
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supporting information
p. 763 - 766
(2018/05/29)
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- Effects of lipophilicity, protecting group and stereochemistry on the antimalarial activity of carbohydrate-derived thiochromans
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A series of novel carbohydrate-derived thiochromans has been successfully synthesized in order to investigate the influence of alkyl substituents on the aromatic ring of the thiophenol moiety in addition to the effect of protecting groups and stereochemistry on the sugar component of the target molecules. Results from the evaluation of the thiochromans for their antimalarial activity against the chloroquine-sensitive (3D7) strain of Plasmodium falciparum suggest that the presence of short chain alkyl substituents, a benzyl ether protecting group and equatorial orientation of the C-4 substituent on the sugar moiety are crucial structural features that impart high antimalarial activity.
- Madumo, Gilbert K.,Moshapo, Paseka T.,Kinfe, Henok H.
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p. 817 - 833
(2018/01/10)
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- Carbonylative Coupling of Alkyl Zinc Reagents with Benzyl Bromides Catalyzed by a Nickel/NN2 Pincer Ligand Complex
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An efficient catalytic protocol for the three-component assembly of benzyl bromides, carbon monoxide, and alkyl zinc reagents to give benzyl alkyl ketones is described, and represents the first nickel-catalyzed carbonylative coupling of two sp3-carbon fragments. The method, which relies on the application of nickel complexed with an NN2-type pincer ligand and a controlled release of CO gas from a solid precursor, works well with a range of benzylic bromides. Mechanistic studies suggest the intermediacy of carbon-centered radicals.
- Andersen, Thomas L.,Donslund, Aske S.,Neumann, Karoline T.,Skrydstrup, Troels
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supporting information
p. 800 - 804
(2017/12/26)
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- Selective Hydrogenations and Dechlorinations in Water Mediated by Anionic Surfactant-Stabilized Pd Nanoparticles
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We report a facile, inexpensive, and green method for the preparation of Pd nanoparticles in aqueous medium stabilized by anionic sulfonated surfactants sodium 1-dodecanesulfonate 1a, sodium dodecylbenzenesulfonate 1b, dioctyl sulfosuccinate sodium salt 1c, and poly(ethylene glycol) 4-nonylphenyl-3-sulfopropyl ether potassium salt 1d simply obtained by stirring aqueous solutions of Pd(OAc)2 with the commercial anionic surfactants further treated under hydrogen atmosphere for variable amounts of time. The aqueous Pd nanoparticle solutions were tested in the selective hydrogenation reactions of aryl-alcohols, -aldehydes, and -ketones, leading to complete conversion to the deoxygenated products even in the absence of strong Br?nsted acids in the reduction of aromatic aldehydes and ketones, in the controlled semihydrogenation of alkynes leading to alkenes, and in the efficient hydrodechlorination of aromatic substrates. In all cases, the micellar media were crucial for stabilizing the metal nanoparticles, dissolving substrates, steering product selectivity, and enabling recycling. What is interesting is also that a benchmark catalyst like Pd/C can often be surpassed in activity and/or selectivity in the reactions tested by simply switching to the appropriate commercially available surfactant, thereby providing an easy to use, flexible, and practical catalytic system capable of efficiently addressing a variety of synthetically significant hydrogenation reactions.
- La Sorella, Giorgio,Sperni, Laura,Canton, Patrizia,Coletti, Lisa,Fabris, Fabrizio,Strukul, Giorgio,Scarso, Alessandro
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supporting information
p. 7438 - 7446
(2018/05/29)
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- Cobalt-catalyzed (Z)-selective semihydrogenation of alkynes with molecular hydrogen
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Cobalt-catalyzed highly (Z)-selective semihydrogenation of alkynes using molecular H2 was developed using commercially available and cheap cobalt precursors. A variety of (Z)-alkenes were obtained in moderate to excellent selectivities [(Z)-alkene/(E)-alkene/alkane ratio up to >99 : 1 : 1] and it was found that the readily available ethylenediamine ligand is crucial in determining the selectivity.
- Chen, Caiyou,Huang, Yi,Zhang, Zongpeng,Dong, Xiu-Qin,Zhang, Xumu
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supporting information
p. 4612 - 4615
(2017/04/28)
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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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- Efficient phosphine-mediated formal C(sp3)-C(sp3) coupling reactions of alkyl halides in batch and flow
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The construction of C(sp3)-C(sp3) bond is an essential chemical transformation in synthetic chemistry due to its abundance in organic scaffolds. Here we demonstrate a valuable adaptation of the Wittig-type chemical procedure to efficiently facilitate C(sp3)-C(sp3) bond formation utilizing a range of alkyl building blocks. Additionally the method is amenable with flow synthesis to afford coupled products in good to excellent yields without laborious purification process.
- Tran,Hock,Gordon,Koenigs,Nguyen
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supporting information
p. 4950 - 4953
(2017/07/11)
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- Alkyl diphenyl phosphine and preparing alkyl diphenyl phosphine payment proportional to production alkyl benzene
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The invention discloses alkyl diphenylphosphine and a method for preparing alkyl diphenylphosphine with co-production of alkylbenzene. The structural formula of alkyl diphenylphosphine is shown in a formula I. The method comprises: adding triphenylphosphine and metal lithium into an organic solvent for reaction for 3-6 hours at room temperature; and cooling the reaction system to 0-10 DEG C, adding halogenated straight-chain alkane for insulating reaction, then raising the temperature of the system to 30-80 DEG C, keeping the temperature to react for 1-3 hours, removing the organic solvent and reducing the pressure and distilling to separately obtain alkyl diphenylphosphine and alkylbenzene. According to the alkyl diphenylphosphine disclosed by the invention, alkyl is directly bonded with P, so that the alkyl diphenylphosphine can be dissolved in most solvents and can be used as a ligand for homogeneous catalysts. By virtue of the method disclosed by the invention, high value straight-chain alkylbenzene is co-produced while straight-chain alkyl diphenylphosphine is prepared by way of a one-pot process. Use of chloro-tert-butane which is relatively high in price and waste of the metal lithium are avoided. The method is simple to operate, efficient, low in energy consumption, low in cost and suitable for large-scaled industrial production.
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Paragraph 0053; 0056-0059
(2017/08/25)
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- With machine phosphine molybdenum complex, preparation method and application
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The invention discloses an organic phosphonium molybdenum complex, a preparation method and application. The organic phosphonium molybdenum complex has the following general formula: Mo[P(Ph)2R]2Cl5, wherein the P(Ph)2R is alkyldiphenylphosphine; the R is linear-chain alkyl with the carbon atom number of 3-10. According to the organic phosphonium molybdenum complex provided by the invention, alkyldiphenylphosphine is adopted as the ligand, and the organic phosphonium molybdenum complex can be dissolved in dicyclopentadiene, and can form a homogeneous system with dicyclopentadiene when used as a main catalyst to catalyze dicyclopentadiene for ring opening polymerization, so that the catalytic efficiency is greatly improved, and the production efficiency of polydicyclopentadiene is improved; the organic phosphonium molybdenum complex is relatively high in catalytic activity, and the polydicyclopentadiene product prepared through adopting the organic phosphonium molybdenum complex as the main catalyst is high in quality and excellent in the mechanical properties, such as, tensile strength and impact strength; the organic phosphonium molybdenum complex is relatively high in chemical stability, insensitive to air and moisture, simple in preparation, low in cost and suitable for popularization and application.
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Paragraph 0051; 0058-0060
(2017/08/31)
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- Photoredox-Assisted Reductive Cross-Coupling: Mechanistic Insight into Catalytic Aryl-Alkyl Cross-Couplings
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Here, we describe a photoredox-assisted catalytic system for the direct reductive coupling of two carbon electrophiles. Recent advances have shown that nickel catalysts are active toward the coupling of sp3-carbon electrophiles and that well-controlled, light-driven coupling systems are possible. Our system, composed of a nickel catalyst, an iridium photosensitizer, and an amine electron donor, is capable of coupling halocarbons with high yields. Spectroscopic studies support a mechanism where under visible light irradiation the Ir photosensitizer in conjunction with triethanolamine are capable of reducing a nickel catalyst and activating the catalyst toward cross-coupling of carbon electrophiles. The synthetic methodology developed here operates at low 1 mol % catalyst and photosensitizer loadings. The catalytic system also operates without reaction additives such as inorganic salts or bases. A general and effective sp2-sp3 cross-coupling scheme has been achieved that exhibits tolerance to a wide array of functional groups.
- Paul, Avishek,Smith, Mark D.,Vannucci, Aaron K.
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p. 1996 - 2003
(2017/02/26)
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- Benzyltin pyrimidine derivatives, their preparation and their use as medicaments
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The invention relates to the field of pharmaceutical chemistry, specifically to benzyl pyrimidine derivatives (I), preparation methods thereof, medicinal compositions containing the derivatives and medical application of the derivatives, in particular, application of the derivatives as an immunosuppressant in autoimmune diseases and organ transplantation.
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Paragraph 0088; 0089
(2017/01/19)
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- Single-Electron-Transfer-Induced Coupling of Alkylzinc Reagents with Aryl Iodides
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Alkylzinc reagents prepared from an alkyllithium and zinc iodide were found to undergo coupling with aryl and alkenyl iodides in the presence of LiI in a mixed solvent consisting of THF and diglyme (1:1). Alkyllithiums, prepared by halogen–lithium exchange between an alkyl iodide and tert-butyllithium, are also converted to alkylarenes through alkylzinc reagents.
- Okura, Keisho,Shirakawa, Eiji
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p. 3043 - 3046
(2016/07/14)
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- Organic chemistry: A general alkyl-alkyl cross-coupling enabled by redox-active esters and alkylzinc reagents
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Alkyl carboxylic acids are ubiquitous in all facets of chemical science, from natural products to polymers, and represent an ideal starting material with which to forge new connections. This study demonstrates how the same activating principles used for decades to make simple C-N (amide) bonds from carboxylic acids with loss of water can be used to make C-C bonds through coupling with dialkylzinc reagents and loss of carbon dioxide. This disconnection strategy benefits from the use of a simple, inexpensive nickel catalyst and exhibits a remarkably broad scope across a range of substrates (>70 examples).
- Qin, Tian,Cornella, Josep,Li, Chao,Malins, Lara R.,Edwards, Jacob T.,Kawamura, Shuhei,Maxwell, Brad D.,Eastgate, Martin D.,Baran, Phil S.
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p. 801 - 805
(2016/06/01)
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- Use of Trifluoromethyl Groups for Catalytic Benzylation and Alkylation with Subsequent Hydrodefluorination
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The electrophilic organofluorophosphonium catalyst [(C6F5)3PF][B(C6F5)4] is shown to effect benzylation or alkylation by aryl and alkyl CF3 groups with subsequent hydrodefluorination, thus resulting in a net transformation of CF3 into CH2-aryl fragments. In the case of alkyl CF3 groups, Friedel-Crafts alkylation by the difluorocarbocation proceeded without cation rearrangement, in contrast to the corresponding reactions of alkyl monofluorides.
- Zhu, Jiangtao,Prez, Manuel,Caputo, Christopher B.,Stephan, Douglas W.
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supporting information
p. 1417 - 1421
(2016/02/14)
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- Diverting Hydrogenations with Wilkinson's Catalyst towards Highly Reactive Rhodium(I) Species
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The addition of Barton's base has a dramatic effect on the classic rhodium(III)-mediated hydrogenations promoted by Wilkinson′s catalyst. Following the initial oxidative addition, a barrierless reductive elimination of HCl from the traditional rhodium(III) intermediates instantly produces a rhodium(I) monohydride species, which is remarkably reactive in the hydrogenation of several internal alkynes and functionalized trisubstituted alkenes. The direct formation of this species is unprecedented upon addition of molecular hydrogen and its catalytic potential has been hitherto barely explored.
- Perea-Buceta, Jesus E.,Fernández, Israel,Heikkinen, Sami,Axenov, Kirill,King, Alistair W. T.,Niemi, Teemu,Nieger, Martin,Leskel?, Markku,Repo, Timo
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supporting information
p. 14321 - 14325
(2016/01/25)
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- Direct C(sp2)-C(sp3) cross-coupling of diaryl zinc reagents with benzylic, primary, secondary, and tertiary alkyl halides
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The direct C(sp2)-C(sp3) cross-coupling of diaryl zinc reagents with benzylic, primary, secondary, and tertiary alkyl halides proceeded in the absence of coordinating ethereal solvents at ambient temperature without the addition of a catalyst. The C(sp2)-C(sp3) cross-coupling showed excellent functional-group tolerance, and products were isolated in high yields, generally without the requirement for purification by chromatography. This process represents an expedient, operationally simple method for the construction of new C(sp2)-C(sp3) bonds. Zinc and you'll miss it. Direct C(sp2)-C(sp3) cross-coupling of diaryl zinc reagents with alkyl halides proceeded rapidly at ambient temperature without a coordinating ethereal solvent or an added catalyst (see scheme). This versatile, operationally simple approach to C(sp2)-C(sp3) bond formation enables the expedient construction of a diverse array of carbon-based structural motifs.
- Dunsford, Jay J.,Clark, Ewan R.,Ingleson, Michael J.
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supporting information
p. 5688 - 5692
(2015/05/19)
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- Rapid Wolff-Kishner reductions in a silicon carbide microreactor
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Wolff-Kishner reductions are performed in a novel silicon carbide microreactor. Greatly reduced reaction times and safer operation are achieved, giving high yields without requiring a large excess of hydrazine. The corrosion resistance of silicon carbide avoids the problematic reactor compatibility issues that arise when Wolff-Kishner reductions are done in glass or stainless steel reactors. With only nitrogen gas and water as by-products, this opens the possibility of performing selective, large scale ketone reductions without the generation of hazardous waste streams.
- Newman, Stephen G.,Gu, Lei,Lesniak, Christoph,Victor, Georg,Meschke, Frank,Abahmane, Lahbib,Jensen, Klavs F.
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supporting information
p. 176 - 180
(2014/01/06)
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- Copper-Catalyzed Reductive Cross-Coupling of Nonactivated Alkyl Tosylates and Mesylates with Alkyl and Aryl Bromides
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A copper-catalyzed reductive cross-coupling reaction of nonactivated alkyl tosylates and mesylates with alkyl and aryl bromides was developed. It provides a practical method for efficient and cost-effective construction of aryl-alkyl and alkyl-alkyl C=C bonds with stereocontrol from readily available substrates. When used in an intramolecular fashion, the reaction enables convenient access to various substituted carbo- or heterocycles, such as 2,3-dihydrobenzofuran and benzochromene derivatives.
- Liu, Jing-Hui,Yang, Chu-Ting,Lu, Xiao-Yu,Zhang, Zhen-Qi,Xu, Ling,Cui, Mian,Lu, Xi,Xiao, Bin,Fu, Yao,Liu, Lei
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supporting information
p. 15334 - 15338
(2016/02/18)
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- Platinum(II) olefin hydroarylation catalysts: Tuning selectivity for the anti-Markovnikov product
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PtII complexes containing unsymmetrical (pyri-dyl)pyrrolide ligands are shown to catalyze the hydroarylation of unactivated alkenes with selectivity for the anti-Markovnikov product. Substitution on the pyrrolide portion of the ligand allows effective tuning of the selectivity to anti-Markovnikov alkylarene products, whereas substitution on the pyridyl portion can promote competitive al-kenylarene production.
- Clement, Marie L.,Grice, Kyle A.,Luedtke, Avery T.,Kaminsky, Werner,Goldberg, Karen I.
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supporting information
p. 17287 - 17291
(2015/02/19)
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- Silver-mediated fluorination of potassium aryltrifluoroborates with Selectfluor Dedicated to Professor Andrea Vasella on the occasion of his 71st birthday
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A simple and practical procedure for the silver-mediated fluorination of aryl- and heteroaryltrifluoroborates with electrophilic fluorine from Selectfluor and LiOH·H2O is presented. The reaction procedure is simple and easy to set up, the process produces fluorinated arenes and heteroarenes in good to excellent yields and a wide range of electronically and structurally diverse substrates are tolerated.
- Dubbaka, Srinivas Reddy,Narreddula, Venkateswara Reddy,Gadde, Satyanarayana,Mathew, Thresen
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p. 9676 - 9681
(2015/01/08)
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- α-alkylation of ketones by trialkylamines under heterogeneous Pd/C catalysis
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Ketones are regioselectively α-alkylated with trialkylamines in toluene at 120 °C in the presence of Pd/C.
- Yoon, Il Chul,Kim, Tae Gyun,Cho, Chan Sik
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p. 1890 - 1892
(2014/05/06)
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- Catalytic synthesis of n-alkyl arenes through alkyl group cross-metathesis
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n-Alkyl arenes were prepared in a one-pot tandem dehydrogenation/olefin metathesis/hydrogenation sequence directly from alkanes and ethylbenzene. Excellent selectivity was observed when (tBuPCP)IrH2 was paired with tungsten monoaryloxide pyrrolide complexes such as W(NAr)(C 3H6)(pyr)(OHIPT) (1a) [Ar = 2,6-i-Pr2C 6H3; pyr = pyrrolide; OHIPT = 2,6-(2,4,6-i-Pr 3C6H2)2C6H3O]. Complex 1a was also especially active in n-octane self-metathesis, providing the highest product concentrations reported to date. The thermal stability of selected olefin metathesis catalysts allowed elevated temperatures and extended reaction times to be employed.
- Dobereiner, Graham E.,Yuan, Jian,Schrock, Richard R.,Goldman, Alan S.,Hackenberg, Jason D.
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supporting information
p. 12572 - 12575
(2013/09/23)
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- Bimetallic oxidative addition involving radical intermediates in nickel-catalyzed alkyl-alkyl Kumada coupling reactions
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Many nickel-based catalysts have been reported for cross-coupling reactions of nonactivated alkyl halides. The mechanistic understanding of these reactions is still primitive. Here we report a mechanistic study of alkyl-alkyl Kumada coupling catalyzed by a preformed nickel(II) pincer complex ([(N 2N)Ni-Cl]). The coupling proceeds through a radical process, involving two nickel centers for the oxidative addition of alkyl halide. The catalysis is second-order in Grignard reagent, first-order in catalyst, and zero-order in alkyl halide. A transient species, [(N2N)Ni-alkyl 2](alkyl2-MgCl), is identified as the key intermediate responsible for the activation of alkyl halide, the formation of which is the turnover-determining step of the catalysis.
- Breitenfeld, Jan,Ruiz, Jesus,Wodrich, Matthew D.,Hu, Xile
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supporting information
p. 12004 - 12012
(2013/09/02)
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- Copper nanoparticle-catalyzed cross-coupling of alkyl halides with Grignard reagents
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A cross-coupling reaction between alkyl bromides and chlorides and various Grignard reagents was carried out in the presence of commercially available copper or copper oxide nanoparticles as a catalyst and an alkyne additive. The catalytic system shows high activity, a broad scope, and good functional group tolerance.
- Kim, Ju Hyun,Chung, Young Keun
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supporting information
p. 11101 - 11103
(2013/11/19)
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- Development of a palladium on boron nitride catalyst and its application to the semihydrogenation of alkynes
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The simple preparative method for a novel palladium supported on boron nitride catalyst (Pd/BN) was accomplished. Pd/BN is widely applicable for the semihydrogenation of mono- as well as disubstituted alkynes to furnish the corresponding alkenes in the presence of diethylenetriamine (DETA), which exhibits both an unprecedented acceleration effect toward the semihydrogenation and a suppression effect with regard to the overhydrogenation to alkanes. Copyright
- Yabe, Yuki,Yamada, Tsuyoshi,Nagata, Saori,Sawama, Yoshinari,Monguchi, Yasunari,Sajiki, Hironao
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supporting information; experimental part
p. 1264 - 1268
(2012/06/15)
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- Iron-catalyzed alkylations of aryl sulfamates and carbamates
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The alkylation of aryl sulfamates and carbamates using iron catalysis is reported. The method constructs sp2-sp3 carbon-carbon bonds and provides synthetically useful yields across a range of substrates (>35 examples). The directing group ability of sulfamates and carbamates, accompanied by their low reactivity toward conventional cross-couplings, renders these substrates useful for the synthesis of polyfunctionalized arenes.
- Silberstein, Amanda L.,Ramgren, Stephen D.,Garg, Neil K.
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supporting information; experimental part
p. 3796 - 3799
(2012/08/28)
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- Nickel(0)/NaHMDS adduct-mediated intramolecular alkylation of unactivated arenes via a homolytic aromatic substitution mechanism
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A variety of polycycles can be synthesized via an intramolecular alkylation cyclization promoted by Ni(PPh3)4 and NaHMDS. Mechanistic investigations support the catalytic nature of Ni0 in the course of TEMPO scavenging experiments and its association with the substrate and NaHMDS to form an adduct by DOSY NMR.
- Beaulieu, Louis-Philippe B.,Roman, Daniela Sustac,Vallee, Frederic,Charette, Andre B.
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supporting information; scheme or table
p. 8249 - 8251
(2012/09/07)
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- Fluorous oxime palladacycle: A precatalyst for carbon-carbon coupling reactions in aqueous and organic medium
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To facilitate precatalyst recovery and reuse, we have developed a fluorous, oxime-based palladacycle 1 and demonstrated that it is a very efficient and versatile precatalyst for a wide range of carbon-carbon bond formation reactions (Suzuki-Miyaura, Sonogashira, Stille, Heck, Glaser-type, and Kumada) in either aqueous or organic medium under microwave irradiation. Palladacycle 1 could be recovered through F-SPE in various coupling reactions with recovery ranging from 84 to 95% for the first cycle. Inductively coupled plasma optical emission spectrometry (ICP-OES) analyses of the Pd content in the crude product from each class of transformation indicated extremely low levels of leaching and the palladacycle could be reused four to five times without significant loss of activity.
- Susanto, Woen,Chu, Chi-Yuan,Ang, Wei Jie,Chou, Tzyy-Chao,Lo, Lee-Chiang,Lam, Yulin
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experimental part
p. 2729 - 2742
(2012/05/21)
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- Alkylboronic esters from copper-catalyzed borylation of primary and secondary alkyl halides and pseudohalides
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Easy access: An unprecedented copper-catalyzed cross-coupling reaction of the title compounds with diboron reagents is described (see scheme; Ts=4-toluenesulfonyl). This reaction can be used to prepare both primary and secondary alkylboronic esters having diverse structures and functional groups. The resulting products would be difficult to access by other means. Copyright
- Yang, Chu-Ting,Zhang, Zhen-Qi,Tajuddin, Hazmi,Wu, Chen-Cheng,Liang, Jun,Liu, Jing-Hui,Fu, Yao,Czyzewska, Maria,Steel, Patrick G.,Marder, Todd B.,Liu, Lei
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supporting information; experimental part
p. 528 - 532
(2012/02/04)
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- Mechanism of efficient anti-markovnikov olefin hydroarylation catalyzed by homogeneous Ir(iii) complexes
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The mechanism of the hydroarylation reaction between unactivated olefins (ethylene, propylene, and styrene) and benzene catalyzed by [(R)Ir(μ-acac-O, O,C3)-(acac-O,O)2]2 and [R-Ir(acac-O,O) 2(L)] (R = acetylacetonato, CH3, CH2CH 3, Ph, or CH2CH2Ph, and L = H2O or pyridine) Ir(iii) complexes was studied by experimental methods. The system is selective for generating the anti-Markovnikov product of linear alkylarenes (61:39 for benzene + propylene and 98:2 for benzene + styrene). The reaction mechanism was found to follow a rate law with first-order dependence on benzene and catalyst, but a non-linear dependence on olefin. 13C-labelling studies with CH313CH2-Ir-Py showed that reversible β-hydride elimination is facile, but unproductive, giving exclusively saturated alkylarene products. The migration of the 13C-label from the α to β-positions was found to be slower than the C-H activation of benzene (and thus formation of ethane and Ph-d 5-Ir-Py). Kinetic analysis under steady state conditions gave a ratio of the rate constants for CH activation and β-hydride elimination (k CH: kβ) of ~0.5. The comparable magnitude of these rates suggests a common rate determining transition state/intermediate, which has been shown previously with B3LYP density functional theory (DFT) calculations. Overall, the mechanism of hydroarylation proceeds through a series of pre-equilibrium dissociative steps involving rupture of the dinuclear species or the loss of L from Ph-Ir-L to the solvento, 16-electron species, Ph-Ir(acac-O,O)2-Sol (where Sol refers to coordinated solvent). This species then undergoes trans to cis isomerization of the acetylacetonato ligand to yield the pseudo octahedral species cis-Ph-Ir-Sol, which is followed by olefin insertion (the regioselective and rate determining step), and then activation of the C-H bond of an incoming benzene to generate the product and regenerate the catalyst.
- Bhalla, Gaurav,Bischof, Steven M.,Ganesh, Somesh K.,Liu, Xiang Yang,Jones,Borzenko, Andrey,Tenn III, William J.,Ess, Daniel H.,Hashiguchi, Brian G.,Lokare, Kapil S.,Leung, Chin Hin,Oxgaard, Jonas,Goddard III, William A.,Periana, Roy A.
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experimental part
p. 69 - 81
(2011/03/21)
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- Deoxygenation of aromatic ketones using transfer hydrogenolysis with Raney nickel in 2-propanol
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Aryl ketones are readily deoxygenated to their corresponding aryl alkanes upon treatment with Raney nickel catalyst in boiling 2-propanol. Taylor & Francis Group, LLC.
- Zuidema, Daniel R.,Williams, Sarah L.,Wert, Katherine J.,Bosma, Karin J.,Smith, Abigail L.,Mebane, Robert C.
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experimental part
p. 2927 - 2931
(2011/09/12)
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- Catalytic dehydroaromatization of n-alkanes by pincer-ligated iridium complexes
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Aromatic hydrocarbons are among the most important building blocks in the chemical industry. Benzene, toluene and xylenes are obtained from the high temperature thermolysis of alkanes. Higher alkylaromatics are generally derived from arene-olefin coupling, which gives branched products-that is, secondary alkyl arenes-with olefins higher than ethylene. The dehydrogenation of acyclic alkanes to give alkylaromatics can be achieved using heterogeneous catalysts at high temperatures, but with low yields and low selectivity. We present here the first catalytic conversion of n-alkanes to alkylaromatics using homogeneous or molecular catalysts-specifically 'pincerg'-ligated iridium complexes-and olefinic hydrogen acceptors. For example, the reaction of n-octane affords up to 86% yield of aromatic product, primarily o-xylene and secondarily ethylbenzene. In the case of n-decane and n-dodecane, the resulting alkylarenes are exclusively unbranched (that is, n-alkyl-substituted), with selectivity for the corresponding o-(n-alkyl)toluene.
- Ahuja, Ritu,Punji, Benudhar,Findlater, Michael,Supplee, Carolyn,Schinski, William,Brookhart, Maurice,Goldman, Alan S.
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experimental part
p. 167 - 171
(2012/03/27)
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