1595-05-7Relevant articles and documents
Palladium Catalysed Coupling Reactions of Chloroaryl Cr(CO)3 Complexes
Scott, William J.
, p. 1755 - 1756 (1987)
Chloroaryl chromium tricarbonyl complexes undergo palladium catalysed coupling reactions with nucleophiles and palladium catalysed olefination reactions with alkenes.
Renewable Wood Pulp Paper Reactor with Hierarchical Micro/Nanopores for Continuous-Flow Nanocatalysis
Koga, Hirotaka,Namba, Naoko,Takahashi, Tsukasa,Nogi, Masaya,Nishina, Yuta
, p. 2560 - 2565 (2017)
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.
Iron-Catalyzed Tunable and Site-Selective Olefin Transposition
Yu, Xiaolong,Zhao, Haonan,Li, Ping,Koh, Ming Joo
supporting information, p. 18223 - 18230 (2020/12/04)
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.
Synthesis of Nitrile-Bearing Quaternary Centers by an Equilibrium-Driven Transnitrilation and Anion-Relay Strategy
Alazet, Sébastien,West, Michael S.,Patel, Purvish,Rousseaux, Sophie A. L.
supporting information, p. 10300 - 10304 (2019/07/04)
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.
Water and Sodium Chloride: Essential Ingredients for Robust and Fast Pd-Catalysed Cross-Coupling Reactions between Organolithium Reagents and (Hetero)aryl Halides
Dilauro, Giuseppe,Quivelli, Andrea Francesca,Vitale, Paola,Capriati, Vito,Perna, Filippo Maria
supporting information, p. 1799 - 1802 (2019/01/25)
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.
Reactivity of the diphosphinodithio ligated nickel(0) complex toward alkyl halides and resultant nickel(i) and nickel(ii)-alkyl complexes
Zhang, Ailing,Wang, Congxiao,Lai, Xiaoyu,Zhai, Xiaofang,Pang, Maofu,Tung, Chen-Ho,Wang, Wenguang
supporting information, p. 15757 - 15764 (2018/11/23)
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.
Photoredox-Assisted Reductive Cross-Coupling: Mechanistic Insight into Catalytic Aryl-Alkyl Cross-Couplings
Paul, Avishek,Smith, Mark D.,Vannucci, Aaron K.
, p. 1996 - 2003 (2017/02/26)
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.
Preparation of arylmagnesium/lithium from aryl bromides and their coupling and substitution reactions in tetrahydrofuran
Gundogdu, Ozlem,Altundas, Ramazan,Kara, Yunus
, (2017/09/26)
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
Facile Hydrogenolysis of C(sp3)–C(sp3) σ Bonds
Fillion, Eric,Beaton, Eric,Nguyen, Yen,Wilsily, Ashraf,Bondarenko, Ganna,Jacq, Jér?me
supporting information, p. 3422 - 3434 (2016/11/13)
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.).
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
Moeti, Lerato P.,Darkwa, James
, p. 236 - 243 (2017/02/10)
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.
