- Palladium Catalysed Coupling Reactions of Chloroaryl Cr(CO)3 Complexes
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Chloroaryl chromium tricarbonyl complexes undergo palladium catalysed coupling reactions with nucleophiles and palladium catalysed olefination reactions with alkenes.
- Scott, William J.
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- Renewable Wood Pulp Paper Reactor with Hierarchical Micro/Nanopores for Continuous-Flow Nanocatalysis
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Continuous-flow nanocatalysis based on metal nanoparticle catalyst-anchored flow reactors has recently provided an excellent platform for effective chemical manufacturing. However, there has been limited progress in porous structure design and recycling systems for metal nanoparticle-anchored flow reactors to create more efficient and sustainable catalytic processes. In this study, traditional paper is used for a highly efficient, recyclable, and even renewable flow reactor by tailoring the ultrastructures of wood pulp. The “paper reactor” offers hierarchically interconnected micro- and nanoscale pores, which can act as convective-flow and rapid-diffusion channels, respectively, for efficient access of reactants to metal nanoparticle catalysts. In continuous-flow, aqueous, room-temperature catalytic reduction of 4-nitrophenol to 4-aminophenol, a gold nanoparticle (AuNP)-anchored paper reactor with hierarchical micro/nanopores provided higher reaction efficiency than state-of-the-art AuNP-anchored flow reactors. Inspired by traditional paper materials, successful recycling and renewal of AuNP-anchored paper reactors were also demonstrated while high reaction efficiency was maintained.
- Koga, Hirotaka,Namba, Naoko,Takahashi, Tsukasa,Nogi, Masaya,Nishina, Yuta
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- Iron-Catalyzed Tunable and Site-Selective Olefin Transposition
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The catalytic isomerization of C-C double bonds is an indispensable chemical transformation used to deliver higher-value analogues and has important utility in the chemical industry. Notwithstanding the advances reported in this field, there is compelling demand for a general catalytic solution that enables precise control of the C═C bond migration position, in both cyclic and acyclic systems, to furnish disubstituted and trisubstituted alkenes. Here, we show that catalytic amounts of an appropriate earth-abundant iron-based complex, a base and a boryl compound, promote efficient and controllable alkene transposition. Mechanistic investigations reveal that these processes likely involve in situ formation of an iron-hydride species which promotes olefin isomerization through sequential olefin insertion/β-hydride elimination. Through this strategy, regiodivergent access to different products from one substrate can be facilitated, isomeric olefin mixtures commonly found in petroleum-derived feedstock can be transformed to a single alkene product, and unsaturated moieties embedded within linear and heterocyclic biologically active entities can be obtained.
- Yu, Xiaolong,Zhao, Haonan,Li, Ping,Koh, Ming Joo
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supporting information
p. 18223 - 18230
(2020/12/04)
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- Synthesis of Nitrile-Bearing Quaternary Centers by an Equilibrium-Driven Transnitrilation and Anion-Relay Strategy
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The efficient preparation of nitrile-containing building blocks is of interest due to their utility as synthetic intermediates and their prevalence in pharmaceuticals. As a result, significant efforts have been made to develop methods to access these motifs which rely on safer and non-toxic sources of CN. Herein, we report that 2-methyl-2-phenylpropanenitrile is an efficient, non-toxic, electrophilic CN source for the synthesis of nitrile-bearing quaternary centers by a thermodynamic transnitrilation and anion-relay strategy. This one-pot process leads to nitrile products resulting from the gem-difunctionalization of alkyl lithium reagents.
- Alazet, Sébastien,West, Michael S.,Patel, Purvish,Rousseaux, Sophie A. L.
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supporting information
p. 10300 - 10304
(2019/07/04)
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- Water and Sodium Chloride: Essential Ingredients for Robust and Fast Pd-Catalysed Cross-Coupling Reactions between Organolithium Reagents and (Hetero)aryl Halides
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Direct palladium-catalysed cross-couplings between organolithium reagents and (hetero)aryl halides (Br, Cl) proceed fast, cleanly and selectively at room temperature in air, with water as the only reaction medium and in the presence of NaCl as a cheap additive. Under optimised reaction conditions, a water-accelerated catalysis is responsible for furnishing C(sp3)–C(sp2), C(sp2)–C(sp2), and C(sp)–C(sp2) cross-coupled products, in competition with protonolysis, within a reaction time of 20 s, in yields of up to 99 %, and in the absence of undesired dehalogenated/homocoupling side products even when challenging secondary organolithiums serve as the starting material. It is worth noting that the proposed protocol is scalable and the catalyst and water can easily and successfully be recycled up to 10 times, with an E-factor as low as 7.35.
- Dilauro, Giuseppe,Quivelli, Andrea Francesca,Vitale, Paola,Capriati, Vito,Perna, Filippo Maria
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supporting information
p. 1799 - 1802
(2019/01/25)
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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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- Preparation of arylmagnesium/lithium from aryl bromides and their coupling and substitution reactions in tetrahydrofuran
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One-pot synthesis of 2-aryltetrahydrofurans was achieved by a coupling reaction between arylmagnesium bromides prepared in situ and tetrahydrofuran under mild conditions. The reaction between ArBr and n-BuLi gave unexpected butylbenzene derivatives in mod
- Gundogdu, Ozlem,Altundas, Ramazan,Kara, Yunus
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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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- Facile Hydrogenolysis of C(sp3)–C(sp3) σ Bonds
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The modification of benzylic quaternary, tertiary, and secondary carbon centers through palladium-catalyzed hydrogenolysis of C(sp3)–C(sp3) σ bonds is presented. When benzyl Meldrum's acid derivatives bearing quaternary benzylic centers are treated under mild hydrogenolysis conditions – palladium on carbon and atmospheric pressure of hydrogen – aromatics substituted with tertiary benzylic centers and Meldrum's acid are obtained with good to excellent yield. Analogously, substrates containing tertiary or secondary benzylic centers yield aromatics substituted with secondary benzylic centers or toluene derivatives, respectively. Furthermore, this strategy is used for the high yielding synthesis of diarylmethanes. The scope of the reductive dealkylation reaction is explored and the limitations with respect to steric and electronic factors are determined. A mechanistic analysis of the reaction is described that consisted of deuterium labelling experiments and hydrogenolysis of enantioenriched derivatives. The investigation shows that the C(sp3)–C(sp3) σ bond-cleaving events occur through a hybrid SN1/SN2 mechanism, in which the palladium center displaces a carbon-based leaving group, namely Meldrum's acid, with inversion of configuration, followed by reductive elimination of palladium to furnish a C?H bond. (Figure presented.).
- Fillion, Eric,Beaton, Eric,Nguyen, Yen,Wilsily, Ashraf,Bondarenko, Ganna,Jacq, Jér?me
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supporting information
p. 3422 - 3434
(2016/11/13)
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- Symmetrically and unsymmetrically substituted bis(pyrazole)-palladium(II) and nickel(II) halides as pre-catalysts for ethylene dimerization and Friedel-Crafts alkylation of toluene and benzene
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Bis(pyrazole)-palladium(II) and nickel(II) halide complexes, [(pz)2PdCl2] (1), [(3,5-Me2pz)2PdCl2] (2), [(3,5-tBu2pz)2PdCl2] (3), [(3,5-Ph2pz)2PdCl2] (4), [(3-CF3,5-Phpz)2PdCl2] (5),[(pz)4NiBr2] (6), [(3,5-Me2pz)2NiBr2] (7), [(3,5-tBu2pz)2NiBr2] (8), [(3,5-Ph2pz)2NiBr2] (9) and [(3-CF3,5-Phpz)2NiBr2] (10), were investigated as catalysts for ethylene oligomerization using four alkylaluminium compounds as co-catalysts in toluene, benzene and chlorobenzene. The palladium complexes with ethylaluminium dichloride (EtAlCl2) in toluene selectively produced ethyl- and butyl- toluenes via a Friedel-Crafts alkylation of toluene from the ethylene and butenes formed from the dimerization of ethylene. On the other hand, the nickel complexes produced a mixture of butenes and their Friedel-Crafts toluene alkylation products, but very little ethyltoluene. Changing the solvent to benzene produced similar alkyl-aromatics but in chlorobenzene the reaction produced butenes and a yellow oil, with a molecular weight between 501 to 509 g mol-1; representing C18-C20 carbon-containing compounds. Similarly changing the co-catalyst to methylaluminoxane (MAO), modified methylaluminoxane (MMAO), diethylaluminium chloride (Et2AlCl) and ethylaluminiumsesquichloride (Et3Al2Cl3) also selectively produced butenes and little or no alkylaromatics.
- Moeti, Lerato P.,Darkwa, James
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p. 236 - 243
(2017/02/10)
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- A facile synthesis of a solvent-dispersible magnetically recoverable Pd0 catalyst for the C-C coupling reaction
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Solvent-dispersible magnetite particles (Fe3O4) functionalized with dopamine (DA) and N,N-dimethylglycine (DMG) were successfully prepared by a one-pot synthesis method with environment-friendly materials. Then Pd0 nanoparticles were anchored onto the functionalized Fe3O4. The prepared materials were thoroughly characterized by TEM, XRD, XPS, FT-IR and VSM. The resultant magnetically recoverable Pd catalyst exhibited excellent catalytic activity for the C-C coupling reaction. In addition, this catalyst revealed high efficiency and stability during recycling stages. This work should be useful for the development and application of a magnetically recoverable Pd catalyst on the basis of green chemistry principles.
- Wu, Li,Yuan, Bin,Liu, Mengmeng,Huo, Hongfei,Long, Yu,Ma, Jiantai,Lu, Gongxuan
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p. 56028 - 56034
(2016/07/06)
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- Synthesis and catalytic reactivity of mononuclear substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes
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The reactions of five dinuclear carbonyl complexes [(η 5-C5Me4R)Mo(CO)3]2 [R = allyl, n Bu, t Bu, Ph, Bz] with I2 in chloroform solution gave the corresponding mononuclear substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes [(η 5-C5Me4R)MoI(CO)3] [R = allyl (1), n Bu (2), t Bu (3), Ph (4), Bz (5)]. The molecular structures of complexes 2, 3 and 5 were determined by X-ray diffraction analysis. The results show that the substituent in the ring can directly affect the Mo-I bond distances; the more sterically hindered the substituent, the longer the Mo-I bond. Friedel-Crafts reactions of aromatic compounds with a variety of alkylation reagents catalyzed by the complexes showed that all of these mononuclear molybdenum carbonyl complexes have catalytic activity in Friedel-Crafts alkylation reactions. Indeed, compared with traditional catalysts, these mononuclear metal carbonyl complexes have obvious advantages such as higher activities, mild reaction conditions, high selectivity, simple post-processing, and environmentally friendly chemistry.
- Ma, Zhi-Hong,Lv, Lin-Qian,Wang, Hong,Han, Zhan-Gang,Zheng, Xue-Zhong,Lin, Jin
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p. 225 - 233
(2016/02/20)
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- Enantioselective hydrogenation of cyclic imines catalysed by Noyori-Ikariya half-sandwich complexes and their analogues
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A method for enantioselective hydrogenation of cyclic imines with gaseous hydrogen has been developed. Easily accessible Noyori-Ikariya Ru(ii) and Rh(iii) complexes can be used directly without an inert atmosphere. Substrate activation has been achieved by trifluoroacetic acid. A new hydroxyl-functionalized complex is reported, showing high activity in transfer hydrogenation.
- Vilhanová,Václavík,?ot,Pechá?ek,Zápal,Pa?out,Maixner,Kuzma,Ka?er
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supporting information
p. 362 - 365
(2016/01/09)
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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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supporting information
p. 3043 - 3046
(2016/07/14)
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- Chromium aryl complexes with N-donor ligands as catalyst precursors for selective ethylene trimerization
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A series of 8-amino-2-arylquinoline ligands (1-6) were synthesized and reacted with CH3CrCl2(thf)3. Under these conditions a CH bond of the 2-aryl substituent is metalated, leading to organochromium complexes with monoanionic tridentate ligands (8-13). The presence of a chromium-carbon σ bond in these complexes has been established by X-ray analysis. Furthermore, 8-(piperidin-1-yl)quinoline (14) was used as neutral bidentate ligand in addition to an external aryl group, leading to complex 15. Finally, the tris-aryl complex 18 was synthesized, which features a rare five-coordinate chromium(III) metal center. All chromium complexes were tested as catalysts for the selective trimerization of ethylene after activation with methylaluminoxane (MAO). Several of the new catalyst precursors show good behavior for the selective trimerization of ethylene. Although chlorido ligands in the catalyst precursor will be substituted by methyl groups during the activation with MAO, there is a clear difference in the catalytic behavior when the complex contains a methyl (or aryl) group prior to addition of MAO. The mechanism of catalyst activation has been studied in more detail with the tris-aryl complex 18.
- Ronellenfitsch, Mathias,Wadepohl, Hubert,Enders, Markus
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supporting information
p. 5758 - 5766
(2015/02/19)
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- Role of sterically demanding chiral dirhodium catalysts in site-selective C-H functionalization of activated primary C-H bonds
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The influence of sterically demanding dirhodium tetracarboxylate catalysts on the site selectivity of C-H functionalization by means of rhodium carbene-induced C-H insertion is described. The established dirhodium tetraprolinate-catalyzed reactions of aryldiazoacetates cause preferential C-H functionalization of secondary C-H bonds as a result of competing steric and electronic effects. The sterically more demanding dirhodium tetrakis(triarylcyclopropanecarboxylate) catalysts, exemplified by dirhodium tetrakis[(R)-(1-(biphenyl)-2,2-diphenylcyclopropanecarboxylate)] [Rh 2(R-BPCP)4], favor C-H functionalization of activated primary C-H bonds. Highly site-selective and enantioselective C-H functionalization of a variety of simple substrates containing primary benzylic, allylic, and methoxy C-H bonds was achieved with this catalyst. The utility of this approach has been demonstrated by the late-stage primary C-H functionalization of (-)-∝-cedrene and a steroid.
- Qin, Changming,Davies, Huw M. L.
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supporting information
p. 9792 - 9796
(2014/07/22)
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- Efficient cross-coupling of aryl Grignard reagents with alkyl halides by recyclable ionic iron(iii) complexes bearing a bis(phenol)-functionalized benzimidazolium cation
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A novel bis(phenol)-functionalized benzimidazolium salt, 1,3-bis(3,5-di-tert-butyl-2-hydroxybenzyl)benzimidazolium chloride (H 3LCl, 1), was designed and used to prepare ionic iron(iii) complexes of the type [H3L][FeX4] (X = Cl, 2; X = Br, 3). Both 2 and 3 were characterized by elemental analysis, Raman spectroscopy, electrospray ionization mass spectrometry and X-ray crystallography. The catalytic performances of 2 and 3 in cross-coupling reactions using aryl Grignard reagents with primary and secondary alkyl halides bearing β-hydrogens were studied. This analysis shows that complex 2 has good potential for alkyl chloride-mediated coupling. In comparison, complex 3 showed slightly lower catalytic activity. After decanting the product contained in the ethereal layer, complex 2 could be recycled at least eight times without significant loss of catalytic activity.
- Xia, Chong-Liang,Xie, Cun-Fei,Wu, Yu-Feng,Sun, Hong-Mei,Shen, Qi,Zhang, Yong
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p. 8135 - 8144
(2013/12/04)
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- Microwave-assisted silica-supported aluminum chloride-catalyzed Friedel-Crafts alkylation
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Microwave irradiation is a popular method in organic synthesis to achieve high yields in shorter reaction times. This decreases total 'man-hours' in a synthetic setting. Another technique used in organic chemistry to decrease manual manipulations, is solid support reagents. The benefits of this approach is that upon completion of a reaction, a simple filtration can be performed which expedites the work-up and also produces less organic waste. Friedel-Crafts alkylation has been explored using microwave chemistry as well as with solid-supported reagents. In comparison with traditional heating, as well as with AlCl3, superior yields were observed with silica-gel bound aluminum chloride (Si-AlClx) when microwave irradiated for only 5 min.
- Zupp, Laurine R.,Campanella, Veronica L.,Rudzinski, Diandra M.,Beland, Franois,Priefer, Ronny
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p. 5343 - 5346
(2012/10/30)
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- An unprecedented iron-catalyzed cross-coupling of primary and secondary alkyl Grignard reagents with non-activated aryl chlorides
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The use of N-heterocyclic carbene ligands in the iron-catalyzed cross-coupling of alkyl Grignards has allowed, for the first time, coupling of non-activated, electron rich aryl chlorides. Surprisingly, the tetrahydrate of FeCl2 was found to be a better pre-catalyst than anhydrous FeCl 2. Primary Grignard reagents coupled in excellent yields while secondary Grignard reagents coupled in modest yields. The use of acyclic secondary Grignard reagents resulted in the formation of isomers in addition to the desired product. These isomeric products were formed via reversible β-hydrogen elimination, indicating that the cross-coupling proceeds through an ionic pathway.
- Perry, Marc C.,Gillett, Amber N.,Law, Tyler C.
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experimental part
p. 4436 - 4439
(2012/09/25)
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- Iron-catalysed, hydride-mediated reductive cross-coupling of vinyl halides and Grignard reagents
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An iron-catalysed, hydride-mediated reductive cross-coupling reaction has been developed for the preparation of alkanes. Using a bench-stable iron(ii) pre-catalyst, reductive cross-coupling of vinyl iodides, bromides and chlorides with aryl- and alkyl Grignard reagents successfully gave the products of formal sp3-sp3 cross-coupling reactions.
- Le Bailly, Bryden A. F.,Greenhalgh, Mark D.,Thomas, Stephen P.
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supporting information; experimental part
p. 1580 - 1582
(2012/03/26)
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- Ionic iron(iii) complexes of bis(phenol)-functionalized imidazolium cations: Synthesis, structures and catalysis for aryl Grignard cross-coupling of alkyl halides
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A series of bis(phenol)-functionalized imidazolium salts, 1,3-bis(4,6-di-R1-2-hydroxybenzyl)-2-R2-4,5-di-R 3-imidazolium chlorides H3LnCl (R1 = tBu, R2 = R3 = H, H3L 1Cl, 1; R1 = CH3, R2 = R3 = H, H3L2Cl, 2; R1 = tBu, R 2 = H, R3 = Cl, H3L3Cl, 3; R 1 = tBu, R2 = CH3, R3 = H, H3L4Cl, 4), were used to produce a novel series of ionic iron(iii) complexes [H3Ln][FeX4] (n = 1, X = Cl, 5; n = 2, X = Cl, 6; n = 3, X = Cl, 7; n = 4, X = Cl, 8; n = 1, X = Br, 9; n = 3, X = Br, 10). All of the complexes were characterized by Raman spectroscopy and electrospray ionization mass spectrometry. Elemental analysis and X-ray crystallography were also used. All of the complexes were non-hygroscopic and air-stable, with five of them existing as solids (5, 7-10) and one as an oil (6) at room temperature. A preliminary catalytic study on the cross-coupling reactions of aryl Grignard reagents with primary and secondary alkyl halides bearing β-hydrogens, revealed that all of the ionic iron(iii) complexes exhibited good to excellent catalytic activity. Complexes 5, 6 and 8 exhibited optimal activity, whereas 7, 9 and 10 showed only moderate activity. Furthermore, by simply decanting the cross-coupling product in the ether layer, complexes 5 and 6 could be reused in at least seven successive runs without significant loss in catalytic activity.
- Deng, Hai-Ning,Xing, Ya-Lin,Xia, Cong-Liang,Sun, Hong-Mei,Shen, Qi,Zhang, Yong
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p. 11597 - 11607
(2013/02/23)
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- Iron(II) complexes with functionalized amine-pyrazolyl tripodal ligands in the cross-coupling of aryl Grignard with alkyl halides
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Structurally distinctive Fe(ii) complexes with furan, thiophene and pyridine functionalized amine-pyrazolyl tripodal hybrid ligands have been synthesized and crystallographically characterized. The tether substituent at the central amine plays an active role in determining the coordination mode of the ligand and the metal geometry. All complexes are catalytically active towards cross-coupling of aryl Grignard reagents with primary and secondary alkyl halides with β-hydrogen under ambient conditions. ESI-MS spectra analysis revealed the ligand-stabilised Fe(ii) and Mg(ii) species. The Royal Society of Chemistry 2011.
- Xue, Fei,Zhao, Jin,Hor, T. S. Andy
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experimental part
p. 8935 - 8940
(2011/10/19)
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- Two flavors of PEPPSI-IPr: Activation and diffusion control in a single NHC-ligated Pd catalyst?
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Abnormal reactivity has been observed in Negishi, Suzuki-Miyaura, and Kumada-Tamao-Corriu cross-couplings in which PEPPSI-IPr (where PEPPSI stands for pyridine enhanced precatalyst preparation, stabilization, and initiation and IPr refers to the NHC ligand) is employed, implicating the presence of two distinct Pd0 species in the catalytic cycle. Polybrominated arenes and organometallic reagents react selectively to give the product of exhaustive polysubstitution regardless of the initial reaction stoichiometry. Competition experiments suggest that, after an initial activation controlled oxidative addition, reductive elimination produces an ultrareactive Pd0 species which consumes all remaining C-Br bonds in the molecule under diffusion control.
- Larrosa, Igor,Somoza, Clara,Banquy, Alexandre,Goldup, Stephen M.
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supporting information; experimental part
p. 146 - 149
(2011/03/20)
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- Air-stable secondary phosphine oxide or chloride (Pre)ligands for cross-couplings of unactivated alkyl chlorides
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In situ generated and crystallographically well-defined, isolated palladium complexes derived from seven novel air-stable secondary phosphine oxides or chlorides enabled challenging Kumada-Corriu cross-couplings of unactivated alkyl chlorides bearing β-hy
- Ackermann, Lutz,Kapdi, Anant R.,Schulzke, Carola
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supporting information; experimental part
p. 2298 - 2301
(2010/08/05)
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- Syntheses, structures, and catalytic ethylene oligomerization behaviors of Bis(phosphanyl)aminenickel(II) Complexes containing N-functionalized pendant groups
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Several N-functionalized bis(phosphanyl)amine ligands respectively containing benzyl, furfuryl, thiophene-2-methyl, thiophene-2-ethyl, and 2-picolyl groups (la-e) were synthesized and characterized. The ligands reacted with (DME)NiBr2 in CH2Cl2 to give their corresponding nickel complexes [Ph2PN(R)PPh2NiBr 2] [R = CH2C6H5 (2a), CH 2C4H3O (2b), CH2C4H 3S (2c), CH2C5H4N (2d), and CH 2CH2C4H3S (2e)], The structures of these complexes were established by single-crystal X-ray crystallography, All these nickel complexes were highly active towards ethylene oligomerization in the presence of methylaluminoxane or Et2AlCl, producing a high content of butene (C4), Especially for 2e, which contains a thiophene-2-ethyl pendant group, the oligomerization products obtained at -40 °C contained 95.9 mol-% C4 fraction with 100 mol-% 1-butene. Over 50 °C, however, these nickel complexes underwent: Friedel-Crafts alkylation of toluene with ethylene and the olefin oligomers.
- Song, Kerning,Gao, Haiyang,Liu, Fengshou,Pan, Jin,Guo, Lihua,Zai, Shaobo,Wu, Qing
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scheme or table
p. 3016 - 3024
(2011/05/14)
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- Functional group tolerant Kumada-Corriu-Tamao coupling of nonactivated alkyl halides with aryl and heteroaryl nucleophiles: Catalysis by a nickel pincer complex permits the coupling of functionalized Grignard reagents
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A nickel(II) pincer complex [(MeNN2)NiCl] (1) catalyzes Kumada-Corriu-Tamao cross coupling of nonactivated alkyl halides with aryl and heteroaryl Grignard reagents. The coupling of octyl bromide with phenylmagnesium chloride was used as a test reaction. Using 3 mol % of 1 as the precatalyst and THF as the solvent, and in the presence of a catalytic amount of TMEDA, the coupling product was obtained in a high yield. The reaction conditions could be applied to cross coupling of other primary and secondary alkyl bromides and iodides. The coupling is tolerant to a wide range of functional groups. Therefore, alkyl halides containing ester, amide, ether, thioether, alcohol, pyrrole, indole, furan, nitrile, conjugated enone, and aryl halide moieties were coupled to give high isolated yields of products in which these units stay intact. For the coupling of ester-containing substrates, O-TMEDA is a better additive than TMEDA. The reaction protocol proves to be efficient for the coupling of Knochel-type functionalized Grignard reagents. Thus aryl Grignard reagents containing electron-deficient and/or sensitive ester, nitrile, amide, and CF3 substituents could be successfully coupled to nonactivated and functionalized alkyl iodides. The catalysis is also efficient for the coupling of alkyl iodides with functionalized heteroaryl Grignard reagents, giving rise to pyridine-, thiophene-, pyrazole-, furan-containing molecules with additional functionalities. Concerning the mechanism of the catalysis, [(MeNN2)Ni-(hetero)Ar] was identified as an intermediate, and the activation of alkyl halides was found to take place through a radical-rebound process.
- Vechorkin, Oleg,Proust, Valerie,Hu, Xile
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supporting information; experimental part
p. 9756 - 9766
(2011/03/19)
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- Palladium-catalyzed cross-coupling alkylation of arenediazonium o-benzenedisulfonimides
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Arenediazonium o-benzenedisulfonimides were reacted with tetramethyltin, tetrabutyltin or trialkylboranes. The reactions, carried out in the presence of palladium(II) derivatives as precatalysts, gave the methylation and alkylation products with good over
- Barbero, Margherita,Cadamuro, Silvano,Dughera, Stefano
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p. 474 - 478
(2008/09/21)
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- Reductive activation of arenes 21. Reaction of products of two-electron reduction of arenecarbonitriles by alkali metals in liquid ammonia with bromo-and dibromoalkanes
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Reductive alkylation of benzonitrile, ortho-, meta-, para-tolunitriles, and 1-naphthonitrile by sequential action of alkali metal and alkyl bromide in liquid ammonia results in corresponding alkylarenes and 1-alkyl-1- cyanocyclohexa-2,5-dienes. The experimental conditions for target synthesis of the specified products are found. A method of synthesis of 1-(ω- bromoalkyl)-1-cyanocyclohexa-2,5-dienes based on the interaction of two-electronic reduction products of aromatic nitriles with α,ω- dibromoalkanes Br(CH2)nBr (n = 3-5) is developed.
- Vaganova,Panteleeva,Yuferov,Rebitva,Shteingarts
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p. 981 - 986
(2008/02/01)
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- meta-directing cobalt-catalyzed diels-alder reactions
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(Chemical Equation Presented) Overcoming the ortho/para rule? The regioselectivity of Diels-Alder reactions with neutral electron demand between 1,3-dienes with alkynes can be controlled by simple cobalt diimine complexes so that the meta-substituted cycloadducts are generated in good yields and excellent regioselectivity (see scheme; DDQ=2,3-dichloro-5,6-dicyano-1,4- benzoquinone).
- Hilt, Gerhard,Janikowski, Judith,Hess, Wilfried
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p. 5204 - 5206
(2007/10/03)
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- New synthetic applications of indium organometallics in cross-coupling reactions
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The use of indium organometallics in multifold and sequential cross-coupling reactions is reported. Triorganoindium reagents (R3In) react, under palladium catalysis, with oligohaloarenes affording the multiple cross-coupling products in a single operation. In the reaction, the three organic groups (alkyl, aryl, alkenyl or alkynyl) attached to indium are efficiently transferred to the electrophile, with only a slight excess of organometallic reagent. We demonstrate that indium organometallics are useful reagents for sequential cross-coupling reactions. This reaction illustrates the high chemoselectivity of R3In. Georg Thieme Verlag Stuttgart.
- Pena, Miguel A.,Perez Sestelo, Jose,Sarandeses, Luis A.
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p. 485 - 492
(2007/10/03)
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- Highly efficient Pd-catalyzed carbonylative cross-coupling reactions with tetraorganoindates
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Tetraorganoindates, which were prepared easily from the reaction of 1 equiv of InCl3 with 4 equiv of organometallics, could be employed as effective nucleophilic cross-coupling partners in Pd-catalyzed carbonylative cross-coupling reactions with a variety of organic electrophiles. The present method gave unsymmetrical ketones and 1,4-diacylbenzenes in good yields with highly efficient transfer of almost all the organic groups attached to the indium under a carbon monoxide atmosphere in THF at 60 °C.
- Lee, Sung Wook,Lee, Kooyeon,Seomoon, Dong,Kim, Sundae,Kim, Hyunseok,Kim, Hyun,Shim, Eunkyong,Lee, Miae,Lee, Seokju,Kim, Misook,Lee, Phil Ho
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p. 4852 - 4855
(2007/10/03)
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- Tetraorganoindates as Nucleophilic Coupling Partners in Pd-Catalyzed Cross-Coupling Reactions
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(Equation presented) In situ generated ate complex In situ-generated tetraorganoindate complexes from the reaction of 1 equiv of indium trichloride with 4 equiv of appropriate organometallics are efficient nucleophiles in Pd-catalyzed cross-coupling reactions. In this novel reaction tetraorganoindates containing methyl, 1°- and 2°-alkyl, vinyl, alkynyl, and aryl groups transfer the four organic groups to a variety of electrophiles with high atom efficiency.
- Lee, Phil Ho,Lee, Sung Wook,Seomoon, Dong
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p. 4963 - 4966
(2007/10/03)
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- Reductive Activation of Arenes: XVI. Anionic Products from Reduction of p-Tolunitrile with Sodium in Liquid Ammonia and Their Reaction with Butyl Bromide
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Study of oxidation, protonation, and alkylation of the products obtained by one- and two-electron reduction of p-tolunitrile with sodium in liquid ammonia showed that these products are, respectively, p-tolunitrile radical anion and 1-cyano-4-methyl-2,5-cyclohexadienyl anion. The latter is formed by protonation of p-tolunitrile dianion with ammonia. The two-electron reduction involves protonation of p-tolunitrile dianion with initial p-tolunitrile, which gives rise to 4-cyanobenzyl anion. The yield of the latter depends on the order of mixing of the reactants. The anionic reduction products react with butyl bromide to afford products corresponding to ipso alkylation with respect to the cyano group, 4-butyltoluene and 3-butyl-3-cyano-6-methyl-1,4-cyclohexadiene, as well as the alkylation product at the benzylic position, 4-pentylbenzonitrile. The formation of 4-butyltoluene indicates the possibility for selective synthesis of p-alkyltoluenes by reductive alkylation of p-tolunitrile.
- Vaganova,Starokon',Shteingarts
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p. 680 - 685
(2007/10/03)
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- Nickel catalyzed cross-coupling of modified alkyl and alkenyl Grignard reagents with aryl- and heteroaryl nitriles: Activation of the C-CN bond
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The nickel catalyzed cross-coupling of alkyl and alkenyl Grignard reagents with aryl nitrile derivatives affords good yields of the corresponding aryl alkanes or aryl alkenes via activation of the C-CN bond. To prevent direct addition of the nucleophile to the nitrile group, the reactivity of the Grignard reagent was modulated by reaction with either LiOt-Bu or PhSLi prior to cross-coupling. The optimum catalyst was determined to be NiCl2(PMe3)2, which is a convenient air stable commercially available complex.
- Miller, Joseph A.,Dankwardt, John W.
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p. 1907 - 1910
(2007/10/03)
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- Nickel catalyzed cross-coupling and amination reactions of aryl nitriles
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Aryl nitriles have been found to participate in cross-coupling and amination reactions via nickel-catalyzed activation of the C-CN bond. With the development of these synthetically useful transformations, aryl nitriles can now be considered along with ary
- Miller, Joseph A.,Dankwardt, John W.,Penney, Jonathan M.
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p. 1643 - 1648
(2007/10/03)
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- Atom-efficient metal-catalyzed cross-coupling reaction of indium organometallics with organic electrophiles
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The novel metal-catalyzed cross-coupling reaction of indium organometallics with organic electrophiles is described. Triorganoindium compounds (R3In) containing alkyl, vinyl, aryl, and alkynyl groups are efficiently prepared from the correspond
- Perez,Sestelo,Sarandeses
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p. 4155 - 4160
(2007/10/03)
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- Synthesis and transformations of metallacycles 20.* Cp2ZrCl2-catalyzed cycloalumination of arylolefins with AlEt3
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The Cp2ZrCl2-catalyzed reaction of arylolefins (styrene, o-and p-methylstyrenes, trans-stilbene, 1,4-diphenyl-1,3-butadiene) with AlEt3 resulting in mono-and disubstituted alumacyclopentanes and substituted alumacyclopropa
- Ibragimov,Khafizova,Satenov,Khalilov,Yakovleva,Rusakov,Dzhemilev
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p. 1574 - 1580
(2007/10/03)
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- Novel Homologation Reaction of Arylzincates Bearing a Leaving Group at the Ortho and Meta Positions
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Arylzincates bearing a leaving group at the ortho, meta, and para positions were generated by iodine/zinc exchange reaction of the corresponding iodoaryl sulfonates with Bu3ZnLi, and their reactivity was investigated via product analysis after hydrolysis and treatment with iodine. Zincates derived from o-iodophenyl triflates and tosylate underwent homologation reaction to give o-butylphenylzinc species. o-Benzyne as an intermediate of the reaction was demonstrated by the lack of regioselectivity for trisubstituted zincates. Zincates derived from m-iodophenyl triflates also underwent homologation leading to m-butylphenylzinc species. Similar product ratios observed in the reactions of regioisomeric trisubstituted iodophenyl triflates as well as the formation of radical reaction byproducts suggested the involvement of m-benzyne intermediate. p-(Trifluoromethane-sulfonyloxy)phenylzincate was thermally stable at room temperature; generation of p-benzyne was not observed.
- Harada, Toshiro,Chiba, Minako,Oku, Akira
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p. 8210 - 8213
(2007/10/03)
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- Palladium-catalyzed cross-coupling reactions of triorganoindium compounds with vinyl and aryl triflates or iodides
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(matrix presented) A novel palladium-catalyzed cross-coupling reaction of organoindium compounds with vinyl and aryl triflates or iodides is described. The reaction proceeds for alkyl-, vinyl-, alkynyl-, and arylindium compounds in excellent yields and high chemoselectivity without any excess of the organometallic. Remarkably, indium organometallics transfer efficiently the three organic groups attached to the metal.
- Perez, Ignacio,Sestelo, Jose Perez,Sarandeses, Luis A.
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p. 1267 - 1269
(2008/02/09)
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- A novel 1,2-migration of arylzincates bearing a leaving group at benzylic position: Application to a three-component coupling of p-iodobenzyl derivatives, trialkylzincates, and electrophiles leading to functionalized p- substituted benzenes
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A three-component coupling of p-iodobenzyl derivatives, trialkylzincates, and electrophiles is described. Lithium trialkylzincates (R3ZnLi) react with p-iodobenzyl methanesulfonate to give benzylzinc reagents p-RC6H4CH2Zn(L). The reaction proceeds through a mechanism involving initial iodine/zinc exchange and the 1,2-migration of the resulting arylzincates. The benzylzinc reagents, thus prepared, are subsequently used in coupling reaction with electrophiles such as aldehydes, ketones, acyl chlorides, tosyl cyanide, and chlorosilanes to give a variety of functionalized p-substituted benzenes. Reactions under Barbier conditions in which the corresponding benzylzinc reagents are generated in the presence of electrophiles work well for Me3ZnLi and for magnesium zincates R3ZnMgBr derived from Grignard reagents. Generation of secondary benzylzinc reagents starting from diethyl 1-(p-iodophenyl)ethyl phosphate and their reaction with electrophiles are also achieved under Barbier conditions. Ketones, allyl bromides, and chlorosilanes are successfully used as electrophiles under these conditions.
- Harada, Toshiro,Kaneko, Takayuki,Fujiwara, Takayuki,Oku, Akira
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p. 9317 - 9332
(2007/10/03)
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- In situ formation of alkenyl- and alkynylboranes for Diels-Alder reactions by boron-silicon exchange with alkenyl- and alkynylsilanes
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A variety of alkenylsilanes underwent transmetallation with BBr3 to afford the corresponding alkenyldibromoboranes in solution. Similarly, the transmetallation of alkynylsilanes with BCl3 afforded alkynyldichloroboranes, A number of the alkenyl- and alkynylboranes are novel and useful Diels-Alder dienophiles. An ionic mechanism for the transmetallation is proposed.
- Singleton, Daniel A.,Leung, Shun-Wang
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p. 157 - 161
(2007/10/03)
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- Dianions of 1,4-Bis(methylene)cyclohexane. Conformational Effects in Cyclic and Acyclic Dilithiated Hydrocarbons
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Dimetalation of 1,4-bis(methylene)cyclohexane results in formation of the p-xylene dianion via the linearly conjugated dianion 4.In contrast, 2-methyl-1,5-hexadiene, an acyclic analogue of 1,4-bis(methylene)cyclohexane, undergoes isomerization via the linearly conjugated dianion 12, rather than hydride elimination.MNDO calculations of the conformation of dilithiated 4 and 12 show that 4 is effectively planar, with a symmetrical distribution of charge.Dilithiated 12 is nonplanar, with an almost right angle bend in the ?-system.The dianion can therefore be considered as two allyl anions which are orthogonal to each other.The difference in calculated conformations of 4 and 12 is advanced as the reason for the different reactivity of the two systems.
- Meyer, Stephanie D.,Mills, Nancy S.,Runnels, Joy B.,Torre, Barbara de la,Ruud, C. Channing,Johnson, David K.
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p. 947 - 952
(2007/10/02)
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- Nickel-induced Conversion of Carbon-Nitrogen into Carbon-Carbon Bonds. One step Transformations of Aryl, Quaternary Ammonium Salts into Alkylarenes and Biaryls
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Aryltrimethylammonium iodides are shown to undergo reaction with Grignard reagents under phosphinate-ligated, low-valent nickel catalysis with the formation of alkylarenes and biaryls.
- Wenkert, Ernest,Han, Ai-Li,Jenny, Christian-Johannes
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p. 975 - 976
(2007/10/02)
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- Structure of ω-Arylalkyl Radicals: A 13C CIDNP Investigation
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Thermolysis of a series of ω-arylalkanoyl m-chlorobenzoyl (and acetyl) peroxides at ca. 100 deg C in cyclohexanone and in hexachloroacetone was studied by using 13C chemically induced dynamic nuclear polarization.Analysis of the observed 13C polarizations indicate that all the three radicals (β-arylethyl, γ-arylpropyl and δ-arylbutyl) have open-chain structures with no evidence for aryl participation resulting in spirocycloalkylcyclohexadienyl radicals.
- Olah, George A.,Krishnamurthy, V. V.,Singh, Brij P.,Iyer, Pradeep S.
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p. 955 - 963
(2007/10/02)
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