- Synthesis, structures and catalytic activity of cyclometalated rhenium complexes
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Thermal reactions of aryl-substituted phosphines or phosphinites with Re2(CO)10 in chlorobenzene resulted in the corresponding five-membered cyclometalated rhenium complexes (1-5) via an intramolecular activation of the C(sp2)-H or C(sp3)-H bond. The only exception occurred in the case of (1-naphthyl)diisopropylphosphinite, which gave a diphosphinite-substituted dinuclear rhenium complex 6. Competition reaction indicated that the aromatic C(sp2)-H bond is more likely to be activated than the C(sp3)-H bond under the same conditions. Photolysis of 1 or 2 in CHX3 led to the cleavage of the Re-C σ bond to yield corresponding phosphine-substituted tetracarbonyl rhenium halides 7-10. Complex 1 reacted with CF3COOH in CH2Cl2 to give addition product 11. Photolysis of cyclorhenated complexes 1-3 with a series of aryl halides in benzene resulted in the stoichiometric formation of biphenyl, together with corresponding phosphine-substituted tetracarbonyl rhenium halides (7, 9, 10, 12, and 13). When base was introduced into the above reaction, a catalytic system was established. Under optimized conditions, complex 1 provided moderate yield of biphenyl in a couple of hours at a [Re] : substrate ratio of 1 : 200. Molecular structures of complexes 1, 6, 9, and 11 were determined by X-ray diffraction.
- Sun, Ruichen,Wang, Tian,Zhang, Shaowei,Chu, Xiaodan,Zhu, Bolin
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Read Online
- Cobalt-catalyzed cross-coupling reactions of aryl- And alkylaluminum derivatives with (hetero)aryl and alkyl bromides
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A simple cobalt complex, such as Co(phen)Cl2, turned out to be a highly efficient and cheap precatalyst for a host of cross-coupling reactions involving aromatic and aliphatic organoaluminum reagents with aryl, heteroaryl and alkyl bromides. New C(sp2)-C(sp2) and C(sp2)-C(sp3) bonds were formed in good to excellent yields and with high chemoselectivity, under mild reaction conditions.
- Dilauro, Giuseppe,Messa, Francesco,Bona, Fabio,Perrone, Serena,Salomone, Antonio
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supporting information
p. 10564 - 10567
(2021/10/19)
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- Synthesis of biaryl ketones and biaryl diketones via carbonylative Suzuki-Miyaura coupling reactions catalyzed by bridged bis(N-heterocyclic carbene)palladium(II) catalysts
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This disclosure relates to bridged bis(N-heterocyclic carbene)palladium(II) complexes, methods of preparing the complexes, and methods of using the complexes in Suzuki-Miyaura coupling reactions.
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Page/Page column 20; 25-26; 29-30
(2021/12/23)
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- Binuclear Palladium Complex Immobilized on Mesoporous SBA-16: Efficient Heterogeneous Catalyst for the Carbonylative Suzuki Coupling Reaction of Aryl Iodides and Arylboronic Acids Using Cr(CO)6 as Carbonyl Source
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Abstract: In this study, a binuclear palladium complex immobilized on the organo-functionalized SBA-16 was prepared and structurally characterized by routine techniques. Characterizations indicated that the mesostructure of SBA-16 was maintained after the immobilization of palladium complex. Then, the prepared nanomaterial was applied as a heterogeneous catalyst in the carbonylative Suzuki coupling reaction of aryl iodides with arylboronic acids using Cr(CO)6 as carbonyl source. The catalyst was efficiently promoted the coupling reactions of various aryl iodides and arylboronic acids to give the corresponding diaryl ketones in excellent yields. Moreover, the catalyst was readily recovered by filtration and could be reused for seven cycles without losing its structural integrity and catalytic activity. Graphic Abstract: [Figure not available: see fulltext.].
- Niakan, Mahsa,Asadi, Zahra,Emami, Mohammad
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p. 404 - 418
(2020/01/03)
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- Cobalt-catalyzed C(sp2)?CN bond activation: Cross-electrophile coupling for biaryl formation and mechanistic insight
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Herein, we report a cross-electrophile coupling of benzonitrile derivatives and aryl halides with a simple cobalt-based catalytic system under mild conditions to form biaryl compounds. Even though the cobalt catalyst is able to activate the C(sp2)?CN bond alone, the use of the AlMe3 Lewis acid enhances the reactivity of benzonitriles and improves the cross-selectivity with barely any influence on the functional group compatibility. X-ray structure determination of an original low-valent cobalt species combined with catalytic and stoichiometric reactions reveals a catalytically active cobalt(I) species toward the aryl halide partner. On the other hand, experimental insights, including cyclic voltammetry experiments, suggest the involvement of a cobalt complex of a lower oxidation state to activate the benzonitrile derivative. Finally, density functional theory calculations support the proposed mechanistic cycle involving two low-valent cobalt species of different oxidation states to perform the reaction.
- Dorval, Céline,Tricoire, Maxime,Begouin, Jeanne-Marie,Gandon, Vincent,Gosmini, Corinne
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p. 12819 - 12827
(2020/11/18)
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- Transition-Metal-Free Oxidative Cross-Coupling of Tetraarylborates to Biaryls Using Organic Oxidants
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Readily prepared tetraarylborates undergo selective (cross)-coupling through oxidation with Bobbitt's salt to give symmetric and unsymmetric biaryls. The organic oxoammonium salt can be used either as a stoichiometric oxidant or as a catalyst in combination with in situ generated NO2 and molecular oxygen as the terminal oxidant. For selected cases, oxidative coupling is also possible with NO2/O2 without any additional nitroxide-based cocatalyst. Transition-metal-free catalytic oxidative ligand cross-coupling of tetraarylborates is unprecedented and the introduced method provides access to various biaryl and heterobiaryl systems.
- Gerleve, Carolin,Studer, Armido
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p. 15468 - 15473
(2020/05/06)
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- Novel and efficient bridged bis(N-heterocyclic carbene)palladium(II) catalysts for selective carbonylative Suzuki–Miyaura coupling reactions to biaryl ketones and biaryl diketones
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Bridged N,N′-substituted bisbenzimidazolium bromide salts (L1, L2, and L3) were synthesized and fully characterized. Reactions of palladium acetate with L1, L2, and L3 afforded corresponding new bridged bis(N-heterocyclic carbene)palladium(II) complexes (C1, C2, and C3) in high yields. The X-ray structure of complex C1 showed that the Pd(II) ion is bonded to the two carbon atoms of the bis(N-heterocyclic carbene) and two bromido ligands are in the cis position, resulting in a distorted square planar geometry. The three Pd(NHC)2Br2 complexes C1, C2, and C3 were evaluated in carbonylative Suzuki–Miyaura coupling reactions of aryl boronic acids with aryl halides and displayed high catalytic activity with low catalyst loading. The coupling reactions of aryl bromides were selective towards the carbonylation product at higher carbon monoxide pressure.
- El Ali, Bassam,Fettouhi, Mohammed,Mansour, Waseem
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- Cu-Mediated arylselenylation of aryl halides with trifluoromethyl aryl selenonium ylides
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An unprecedented arylselenylation of aryl halides with trifluoromethyl aryl selenonium ylides in the presence of copper is described. The reaction proceeded at 100-140 °C under ligand- and additive-free conditions for 3-20 h to form a variety of unsymmetrical diaryl selenides in good to high yields. Arylselenylation is easy to operate, has good functional group tolerance, and demonstrates the different reaction profiles of trifluoromethyl aryl selenonium ylides from the homologous trifluoromethyl aryl sulfonium ylides.
- Wu, Shuai,Shi, Jin,Zhang, Cheng-Pan
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supporting information
p. 7468 - 7473
(2019/08/20)
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- Palladium nanocatalysts in glycerol: Tuning the reactivity by effect of the stabilizer
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Palladium nanoparticles (PdNPs) prepared in neat glycerol containing TPPTS (tris(3-sulfophenyl)phosphine trisodium salt) or cinchona-based alkaloids (cinchonidine, quinidine) as capping agents, were applied as catalysts in fluoride-free Hiyama couplings and conjugate additions with the aim of evaluating the influence of the stabilizer in the catalytic reactivity. Therefore, PdNPs stabilized by phosphine favored C–C cross-couplings, whereas those containing alkaloids showed enhanced suitability for C–C homo-couplings and conjugate additions. The metal/stabilizer coordination mode, i.e. Pd–P dative bond and π-π interaction between quinoline moiety and palladium surface, is certainly key for the stabilization of different active metallic species and then promoting distinctive catalytic pathways.
- Reina, Antonio,Serrano-Maldonado, Alejandro,Teuma, Emmanuelle,Martin, Erika,Gómez, Montserrat
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- Facile routes to abnormal-NHC-cobalt(II) complexes
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Deprotonation of [IPrPh]I (1) with Co{N(SiMe3)2}2 readily affords the abnormal N-heterocyclic carbene (aNHC) complex (aIPrPh)2CoI2 (2) (aIPrPh = 1,3-bis(2,6-iPr2C6H3)-2-phenyl-imidazol-4-ylidene). Treatment of 1 with NaHBEt3 yields (aIPrPh)BEt3 (3) that serves as an aNHC-transfer agent and yields (aIPrPh)Co{N(SiMe3)2}2 (4) on reaction with Co{N(SiMe3)2}2.
- Ghadwal, Rajendra S.,Lamm, Jan-Hendrik,Rottsch?fer, Dennis,Schürmann, Christian J.,Demeshko, Serhiy
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supporting information
p. 7664 - 7667
(2017/07/11)
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- In Situ Generation of ArCu from CuF2 Makes Coupling of Bulky Aryl Silanes Feasible and Highly Efficient
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A bimetallic system of Pd/CuF2, catalytic in Pd and stoichiometric in Cu, is very efficient and selective for the coupling of fairly hindered aryl silanes with aryl, anisyl, phenylaldehyde, p-cyanophenyl, p-nitrophenyl, or pyridyl iodides of conventional size. The reaction involves the activation of the silane by CuII, followed by disproportionation and transmetalation from the CuI(aryl) to PdII, upon which coupling takes place. CuIII formed during disproportionation is reduced to CuI(aryl) by excess aryl silane, so that the CuF2 system is fully converted into CuI(aryl) and used in the coupling. Moreover, no extra source of fluoride is needed. Interesting size selectivity towards coupling is found in competitive reactions of hindered aryl silanes. Easily accessible [PdCl2(IDM)(AsPh3)] (IDM = 1,3-dimethylimidazol-2-ylidene) is by far the best catalyst, and the isolated products are essentially free from As or Pd (2: In the Cu-promoted Hiyama process, CuF2 plays the role of two reagents to provide full conversion into the fluoride and copper is also required to transform bulky trialkoxysilanes in situ into CuAr. CuAr immediately transmetalates to Pd, which makes the otherwise inaccessible Pd-catalyzed coupling of bulky arylsilanes feasible and highly efficient.
- Delpozo, Juan,Casares, Juan A.,Espinet, Pablo
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supporting information
p. 4274 - 4284
(2016/03/16)
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- Palladacycles promote the base-free homocoupling of arylboronic acids in air at room temperature
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Homocoupling of arylboronic acids can be successfully achieved in commercial grade THF using [Pd(Phbz)(X)(PPh3)] palladacycles as catalysts (Phbz = N-phenylbenzaldimine; X = imidate or acetate). Symmetric biaryls were obtained in good yields working under mild conditions in an air atmosphere at room temperature. The reaction occurs without the addition of an exogenous base. The reaction conditions were optimized to provide the homocoupled products in excellent yield. Evidence for the transmetallation step being important for precatalyst activation has been gathered. The influence of electronic properties of the arylboronic acids on the outcome of the homocoupling reaction has been assessed through competition experiments. This journal is
- Kapdi, Anant R.,Dhangar, Gopal,Serrano, Jose Luis,De Haro, Jose A.,Lozano, Pedro,Fairlamb, Ian J. S.
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p. 55305 - 55312
(2015/02/18)
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- Single-electron-transfer-induced coupling of arylzinc reagents with aryl and alkenyl halides
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Arylzinc reagents, prepared from aryl halides/zinc powder or aryl Grignard reagents/zinc chloride, were found to undergo coupling with aryl and alkenyl halides without the aid of transition-metal catalysis to give biaryls and styrene derivatives, respectively. In this context, we have already reported the corresponding reaction using aryl Grignard reagents instead of arylzinc reagents. Compared with the Grignard cross-coupling, the present reaction features high functional-group tolerance, whereby electrophilic groups such as alkoxycarbonyl and cyano groups are compatible as substituents on both the arylzinc reagents and the aryl halides. Aryl halides receive a single electron and thereby become activated as the corresponding anion radicals, which react with arylzinc reagents, thus leading to the cross-coupling products. Arylzinc reagents were found to undergo coupling with aryl and alkenyl halides to give biaryl and styrene derivatives, respectively. The cross-coupling, which features high functional-group tolerance, proceeds through a single-electron-transfer mechanism and thus does not require the aid of transition-metal catalysis.
- Shirakawa, Eiji,Tamakuni, Fumiko,Kusano, Eugene,Uchiyama, Nanase,Konagaya, Wataru,Watabe, Ryo,Hayashi, Tamio
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supporting information
p. 521 - 525
(2014/01/23)
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- Copper-catalyzed Hiyama coupling of (hetero)aryltriethoxysilanes with (hetero)aryl iodides
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A CuI-catalyzed Hiyama coupling was achieved, which proceeds in the absence of an ancillary ligand for aryl-heteroaryl and heteroaryl-heteroaryl couplings. A P,N-ligand is required to obtain the best product yields for aryl-aryl couplings. In addition to facilitating transmetalation, CsF is also found to function as a stabilizer of the [CuAr] species, potentially generated as an intermediate after transmetalation of aryltriethoxysilanes with Cu I-catalysts in the absence of ancillary ligands.
- Gurung, Santosh K.,Thapa, Surendra,Vangala, Adarsh S.,Giri, Ramesh
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p. 5378 - 5381
(2013/11/06)
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- Catalytic decarboxylative fluorination for the synthesis of Tri- and difluoromethyl arenes
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Treatment of readily available α,α-difluoro- and α-fluoroarylacetic acids with Selectfluor under Ag(I) catalysis led to decarboxylative fluorination. This operationally simple reaction gave access to tri- and difluoromethylarenes applying a late-stage fluorination strategy. Translation to [18F]labeling is demonstrated using [ 18F]Selectfluor bis(triflate), a reagent affording [ 18F]tri- and [18F]difluoromethylarenes not within reach with [18F]F2.
- Mizuta, Satoshi,Stenhagen, Ida S.R.,O'Duill, Miriam,Wolstenhulme, Jamie,Kirjavainen, Anna K.,Forsback, Sarita J.,Tredwell, Matthew,Sandford, Graham,Moore, Peter R.,Huiban, Mickael,Luthra, Sajinder K.,Passchier, Jan,Solin, Olof,Gouverneur, Véronique
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supporting information
p. 2648 - 2651
(2013/07/11)
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- Stille coupling involving bulky groups feasible with gold cocatalyst
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Gold shuttle: Bulky groups, which will not (or only very sluggishly) undergo Stille coupling with stannanes and inexpensive ligands, can be efficiently coupled using bimetallic catalysis. A gold cocatalyst serves as an efficient shuttle to convey the bulky group from tin to palladium by reducing the steric crowding in the transition-states (see scheme). Copyright
- Delpozo, Juan,Carrasco, Desiree,Perez-Temprano, Monica H.,Garcia-Melchor, Max,Alvarez, Rosana,Casares, Juan A.,Espinet, Pablo
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supporting information
p. 2189 - 2193
(2013/04/10)
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- Vasicine catalyzed direct C-H arylation of unactivated arenes: Organocatalytic application of an abundant alkaloid
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Vasicine, a quinazoline alkaloid isolated from Adhatoda vasica, has been employed as an organocatalyst for direct C-H arylation of unactivated arenes with aryl iodides/bromides without the assistance of any transition metal catalyst. A number of sensitive functional groups such as methyl, methoxy, O-benzyl, acetyl, and amino were well tolerated under present reaction conditions. Mechanistic investigation supported the involvement of radical intermediates.
- Sharma, Sushila,Kumar, Manoranjan,Kumar, Vishal,Kumar, Neeraj
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supporting information
p. 4868 - 4871
(2013/08/28)
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- Imidazole and imidazoline derivatives as N-donor ligands for nickel-catalyzed kumada-tamao-corriu coupling
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Imidazole and imidazoline (dihydroimidazole) derivatives can serve as simple and efficient ligands for the nickel-catalyzed Kumada-Tamao-Corriu coupling reaction. Among the imidazole and imidazoline derivatives in our investigations, the 2-phenyllimidazoline-nickel (II) chloride complex exhibited the highest catalytic activity.
- Iwamoto, Ryo,Hayashi, Masahiko
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p. 713 - 718
(2013/08/15)
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- Silver catalyzed C-C and C-S coupling of aryl halides and thiols with boronic acids
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An efficient Ag(I) catalyzed carbon-carbon and carbon-sulfur bond formation reaction of aryl halides and thiols with boronic acids has been demonstrated. Using this protocol, substrates with a wide range of functional group including electron-rich, and electron deficient substituents have been explored. These reactions are particularly useful to prepare symmetrical and unsymmetrical biphenyls and thioethers. These products were isolated in high yield.
- Das, Rima,Chakraborty, Debashis
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p. 7023 - 7027
(2013/01/15)
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- Synthesis of triethylphosphite complexes of nickel(II) and palladium(II) with tridentate Schiff base ligand for catalytic application in carbon-carbon coupling reactions
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Air stable Ni(II) and Pd(II) complexes viz. [Ni(LS)(P(OEt)3)] (1), [Ni(LN)(P(OEt)3)] (2), [Pd(LS)(P(OEt)3)] (3) and [Pd(LN)(P(OEt)3)] (4) [where LS and LN are dianions of N-(2-mercaptophenyl)salicylideneimine and N-(2-mercaptophenyl)naphthylideneimine respectively] have been synthesized and characterized by analytical and spectral (electronic, FT-IR, 1H, 13C and 31P NMR) methods. The 1H-31P HMBC spectrum established the coupling of phosphorus with the azomethine proton of the Schiff base and the aliphatic protons of triethylphosphite. Novel Ni(II) and Pd(II) complexes exhibited good catalytic activity in Kumada-Tamao-Corriu and Suzuki-Miyaura coupling reactions respectively.
- Tamizh, M. Muthu,Karvembu
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- Fluoroform-derived CuCF3 for low-cost, simple, efficient, and safe trifluoromethylation of aryl boronic acids in air
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Easy does it: Aryl boronic acids undergo smooth and selective trifluoromethylation with low-cost fluoroform-derived CuCF3 in DMF in non-dried air. The reaction occurs under mild conditions (1 atm, room temperature), exhibits unprecedented funct
- Novak, Petr,Lishchynskyi, Anton,Grushin, Vladimir V.
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supporting information; experimental part
p. 7767 - 7770
(2012/08/29)
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- Cross-coupling of aryl grignard reagents with aryl iodides and bromides through SRN1 pathway
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Game, SET, and match: Aryl Grignard reagents undergo coupling with aryl halides when toluene is used as a solvent in combination with a small amount of tetrahydrofuran (see scheme). The reaction proceeds through an SRN1 mechanism, and does not require any transition metal catalysts.
- Shirakawa, Eiji,Hayashi, Yumi,Itoh, Ken-Ichi,Watabe, Ryo,Uchiyama, Nanase,Konagaya, Wataru,Masui, Seiji,Hayashi, Tamio
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supporting information; experimental part
p. 218 - 221
(2012/03/26)
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- Chemoselective transfer of allyl or phenyl group from allyl(phenyl)germanes in Pd-catalyzed reactions with aryl halides
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Treatment of chloro(phenyl)germanes with allylmagnesium bromide yielded allyl(phenyl)germanes. Coupling of the allyl- (phenyl)germanes with aryl halides in 1,4-dioxane in the presence of aqueous NaOH and Pd catalyst resulted in Heck-type transfer of the allyl group providing the corresponding allylated aryls. On the other hand, reaction of allyl(phenyl)germanes with SbF5 intercalated in graphite in toluene and subsequent treatment of the resulting germanyl fluorides with TBAF generates reactive hypervalent fluorogermanates that undergo Stille-like Pd-catalyzed cross-coupling with aryl halides in wet toluene to provide biaryls.
- Pitteloud, Jean-Philippe,Liang, Yong,Wnuk, Stanislaw F.
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supporting information; experimental part
p. 967 - 969
(2011/12/05)
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- Copper-catalyzed trifluoromethylation of aryl boronic acids using a CF 3+ reagent
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A copper-catalyzed process for trifluoromethylation of aryl, heteroaryl, and vinyl boronic acids has been developed. The reaction is conducted under mild conditions and shows tolerance to moisture and a variety of functional groups.
- Xu, Jun,Luo, Dong-Fen,Xiao, Bin,Liu, Zhao-Jing,Gong, Tian-Jun,Fu, Yao,Liu, Lei
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scheme or table
p. 4300 - 4302
(2011/06/21)
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- New bicyclic phosphorous ligands: Synthesis, structure and catalytic applications in ionic liquids
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New azadioxaphosphabicyclo[3.3.0]octane ligands showing a trans arrangement with regard to the two five-membered heterocycles, were obtained as a mixture of three conformers, in agreement with molecular modelling studies. The stability of oxaphosphane ligands was studied under basic catalytic conditions, monitored by NMR spectroscopy. Palladium catalytic systems containing these ligands were active in Suzuki C-C cross-coupling reactions between phenylboronic acid and aryl halides (bromide and chloride derivatives) bearing electron-donor or electron-withdrawing substituents, in both organic and ionic liquid solvents. The catalytic systems showed a high stability even under the most severe reaction conditions used in this work. The ionic liquid catalytic phase could be recycled up to ten times without significant activity loss. Copyright
- Escárcega-Bobadilla, Martha V.,Teuma, Emmanuelle,Masdeu-Bultó, Anna M.,Gómez, Montserrat
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experimental part
p. 421 - 428
(2011/03/18)
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- Fluoride-promoted cross-coupling of chloro(mono-, di-, or triphenyl)germanes with aryl halides in "moist" toluene. Multiple transfer of the phenyl group from organogermane substrates and comparison of the coupling efficiencies of chloro(phenyl)germanes with their corresponding stannane and silane counterparts
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The trichlorophenyl-, dichlorodiphenyl-, and chlorotriphenylgermanes undergo Pd-catalyzed cross-couplings with aryl bromides and iodides in the presence of tetrabutylammonium fluoride in toluene with addition of the measured amount of water. One chloride ligand on the Ge center allows efficient activation by fluoride to promote transfer of one, two, or three phenyl groups from the organogermanes. The corresponding chlorophenylstannanes were found to be more reactive than chlorophenylsilanes, which in turn were more effective than chlorophenylgermanes. One chloride ligand on the Ge or Si center allows efficient activation by fluoride to promote transfer of up to three aryl groups from germane or silicon. However, no haloligand was necessary to be present on the Sn center, since tetraphenyltin efficiently transferred up to four phenyl groups during fluoride-promoted couplings with aryl halides. 19F NMR studies suggested formation of the fluorophenylgermanes and the hypervalent germanate species as possible intermediates.
- Pitteloud, Jean-Philippe,Zhang, Zun-Ting,Liang, Yong,Cabrera, Laura,Wnuk, Stanislaw F.
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supporting information; experimental part
p. 8199 - 8212
(2011/03/18)
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- Tert-butoxide-mediated arylation of benzene with aryl halides in the presence of a catalytic 1,10-phenanthroline derivative
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Sodium tert-butoxide mediates the coupling of aryl halides with benzene derivatives without the aid of transition metal catalysts but with a catalytic 1,10-phenanthroline derivative.
- Shirakawa, Eiji,Itoh, Ken-Ichi,Higashino, Tomohiro,Hayashi, Tamio
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supporting information; experimental part
p. 15537 - 15539
(2010/12/30)
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- Nickel/magnesium-lanthanum mixed oxide catalyst in the Kumada-coupling
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A new, heterogeneous, magnesium-lanthanum mixed oxide solid base-supported nickel(ii) catalyst was developed. The catalyst was used successfully in the Kumada coupling of aryl halides, especially aryl bromides. The optimal reaction conditions of the coupling were determined.
- Kiss, Arpad,Hell, Zoltan,Balint, Maria
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experimental part
p. 331 - 335
(2010/02/16)
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- Suzuki- and Heck-type cross-coupling with palladium nanoparticles immobilized on spherical polyelectrolyte brushes
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We report on a systematic study of the use of palladium nanoparticlesimmo bilized on spherical polyelectrolyte brushes - Pd@SPB - for Heck- and Suzuki-type coupling reactions. The spherical polyelectrolyte brush particles serving as carriers for the palladium nanoparticles consist of a solid polystyrene core with a radiusof 46 nm onto which long chains of cationic polyelectrolytesare grafted. The palladium nanoparticles have directly been generated within this brush layer and the stabilization of the nanoparticlesis effected by the colloidal carriers, no further surface stabilization is necessary. We demonstrate that these composite particles present robust catalysts for the Heck- and Suzuki-type coupling reactions. This was shown by carrying out the Suzuki- and Heck-type coupling reactionsat relatively low temperatures (Suzuki reaction: 50°C, Heck reaction: 70°C). We demonstrate that the catalytic composite particles are not changed by these reaction conditions and retain their full activity for at least four runs. The yields obtained for both reactions are good to excellent. The mild operation conditions of the palladium nanoparticles are traced back to the absence of surface stabilization. Further mechanistic implications are discussed.
- Proch,Mei,Rivera Villanueva,Lu,Karpov,Ballauff,Kempe
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experimental part
p. 493 - 500
(2009/04/06)
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- Palladium-catalyzed carbonylative cross-coupling reaction of triarylantimony dicarboxylates with arylboronic acids: Synthesis of biaryl ketones
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A novel palladium-catalyzed three-component carbonylative coupling reaction by use of triarylantimony diacetate, arylboronic acid and carbon monoxide (1 atm) could be attained under mild reaction conditions without any base as an additive. The reaction can be applied to a wide range of triarylantimony diacetates and boronic acids to afford the corresponding unsymmetrical biaryl ketones in good yields.
- Qin, Weiwei,Yasuike, Shuji,Kakusawa, Naoki,Kurita, Jyoji
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p. 2949 - 2953
(2008/12/21)
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- A new palladium catalyzed protocol for atom-efficient cross-coupling reactions of?triarylbismuths with aryl halides and triflates
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A new palladium catalyzed protocol for an atom-efficient cross-coupling reaction of triarylbismuths with aryl halides and triflates has been described. The palladium catalytic system with Cs2CO3 base was found to be very efficient in DMA solvent to furnish excellent yields of cross-coupled functionalized biaryls in short reaction times.
- Rao, Maddali L.N.,Jadhav, Deepak N.,Banerjee, Debasis
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p. 5762 - 5772
(2008/09/21)
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- Palladium catalyzed Suzuki C-C couplings in an ionic liquid: Nanoparticles responsible for the catalytic activity
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A new family of functionalized ligands derived from norborn-5-ene-2,3- dicarboxylic anhydride has been used in Suzuki C-C cross-couplings between aryl boronic acids and aryl bromide derivatives in [BMI][PF6] (BMI = 1-n-butyl-3-methyl-imidazolium), using palladium acetate as catalytic precursor. High conversions and yields are obtained when amine ligands containing hydroxy groups are involved. TEM analyses after catalysis show the formation of small nanoparticles, in contrast to the agglomerates observed when nanoparticles are intentionally preformed, with a consequent decrease in the catalytic activity in the latter case. Some tests, including the correlation effect between solvent and ligand, are carried out to try to identify the true nature of the catalyst. All the results obtained suggest that formation of nanoparticles is required to lead to a catalytically active system. The Royal Society of Chemistry.
- Fernandez, Fernando,Cordero, Beatriz,Durand, Jerome,Muller, Guillermo,Malbosc, Franois,Kihn, Yolande,Teuma, Emmanuelle,Gomez, Montserrat
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p. 5572 - 5581
(2008/09/17)
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- Magnesiation of electron-rich aryl bromides and their use in nickel-catalyzed cross-coupling reactions
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Electron-rich aryl bromides are rapidly converted to the corresponding lithium triarylmagnesiates with (n-Bu)3MgLi, which undergo efficient nickel-catalyzed Kumada-Corriu cross-coupling reactions with a variety of aryl and alkenyl bromides, chlorides, tosylates, and triflates.
- Lau, Stephen Y. W.,Hughes, Greg,O'Shea, Paul D.,Davies, Ian W.
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p. 2239 - 2242
(2008/02/03)
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- Carbonylative cross-coupling reaction of ethynylstibane with aryl iodides
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Palladium-catalyzed carbonylative cross-coupling reaction of ethynylstibane (Ph-=-SbPh2) and aryl iodides (Ar-I) is described. The reaction of the stibanes and the halides under 1 atm of carbon monoxide in N,N-dimethylacetamide using a combination of 5 mol% Pd(OAc)2 and 4 equivalents (20 mol%) of PPh3 brought about carbonylative cross-coupling reaction to afford arylethynylketones [ArC(O)-=-Ph] in good yields along with a small amount of directly coupled products, aryl acetylens (Ar-=-Ph). Formation of the side product was completely suppressed by conducting the reaction under high CO pressure (20 atm) conditions. The present method provides a variety of carbonylated products in good yield even with electron-deficient aryl iodides which usually give inferior results due to their tendency to undergo decarbonylation in the cross-coupling reaction of ethynylstibanes and acyl halides.
- Kakusawa, Naoki,Kurita, Jyoji
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p. 699 - 702
(2007/10/03)
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- Oxidative C-H activation/C-C bond forming reactions: Synthetic scope and mechanistic insights
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This paper describes a new palladium-catalyzed method for C-H activation/carbon-carbon bond formation with hypervalent iodine arylating agents. This transformation has been applied to a variety of arene and benzylic substrates containing different directing groups (pyridines, quinolines, oxazolidinones, and amides) and proceeds with high levels of regiocontrol. Mechanistic experiments provide preliminary evidence in support of an unusual mechanism for this transformation involving a Pd(II)/Pd(IV) catalytic cycle. Copyright
- Kalyani, Dipannita,Deprez, Nicholas R.,Desai, Lopa V.,Sanford, Melanie S.
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p. 7330 - 7331
(2007/10/03)
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- Use of "homeopathic" ligand-free palladium as catalyst for aryl-aryl coupling reactions
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We have previously shown that the use of ligand-free palladium employing Pd(OAc)2 as catalyst precursor in the Heck reaction of aryl bromides is possible if low catalyst loadings, typically between 0.01-0.1 mol % are used. We have now tested this phenomenon, which we have dubbed " homeopathic" palladium, in biaryl formation using the Suzuki, the Negishi and the Kumada cross-coupling reactions. The Suzuki reaction of aryl bromides, both activated and deactivated, is possible using 0.02-0.05 mol % of Pd(OAc)2. In this reaction turnover frequencies up to 30,000 have been reached with activated substrates. Even aryl chlorides could be reacted if strongly electron-withdrawing substituents were present. The Negishi coupling with a variety of arylzinc halides was possible on aryl bromides containing electron-withdrawing substituents. The Kumada reaction only gave low yields of products under "homeopathic' conditions.
- Alimardanov, Asaf,Schmieder-Van De Vondervoort, Lizette,De Vries, Andre H. M.,De Vries, Johannes G.
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p. 1812 - 1817
(2007/10/03)
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- Palladium-catalyzed arylation of α,α-disubstituted arylmethanols via cleavage of a C-C or a C-H bond to give biaryls
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The palladium-catalyzed arylation of α,α-disubstituted arylmethanols with aryl halides proceeds not only via C-H bond cleavage at the ortho-position, but also via cleavage of the sp2-sp3 C-C bond with the liberation of ketones (β-carbon elimination) to give the corresponding biaryls. Both reactions appear to occur through common arylpalladium(II) alcoholate intermediates. The results of systematic studies with respect to which C-C or C-H bond is preferentially cleaved in the arylation are reported. Among the important findings is the selective elimination of ortho-substituted aryl groups even from aryl(diphenyl)methanols due to steric reasons. Thus, various biaryls having ortho-substituents can be produced efficiently by treatment of the corresponding aryl(diphenyl or dimethyl)methanols with aryl bromides and chlorides.
- Terao, Yoshito,Wakui, Hiroyuki,Nomoto, Michiyo,Satoh, Tetsuya,Miura, Masahiro,Nomura, Masakatsu
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p. 5236 - 5243
(2007/10/03)
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- Comparison between PdCl2(PPh3)2- and NiCl2(PPh3)2-catalyzed cross-coupling of aryl halides by intramolecularly stabilized dialkylaluminum reagents
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The catalytic activities of PdCl2(PPh3)2 and of NiCl2(PPh3)2 in cross coupling of some chloro- and bromoarenes with intramolecularly stabilized aluminum complexes [R2AlOCH2CH2NMe2]2 (R = Ph, PhC≡C, PhCH2, Et and i-Bu) are compared. The palladium catalyst promotes clean cross-alkylation of aryl bromides indifferently to the nature of the R groups of the alkylating reagents, but does not activate aryl chlorides. The nickel complex catalyzes cross-alkylation of both aryl bromides and chlorides, provided the R groups do not have β-hydrogen atoms. Diethyl- and diisobutylaluminum complexes that disproportionate in the presence of the nickel catalyst cause substantial hydrogenolysis of the aryl halides.
- Gelman,Hoehne,Schumann,Blum
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p. 591 - 594
(2007/10/03)
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- Synthesis and characterization of hexaaryltellurium (TeAr6); The first neutral hexaarylated element compound
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Te(C6H4-CF3)6 1a was obtained by the unique one-pot reaction of LiC6H4-4-CF3 with TeCl4. The Te atom resides in the highest oxidation state (Te(VI)) having six C-Te bonds in 1a. Compound la is extremely thermally stable and not light sensitive unlike tetraorganotellurium compounds. The X-ray crystallographic analysis of 1a revealed a rare example of approximately T(h) molecular symmetry.
- Minoura, Mao,Sagami, Takao,Miyasato, Masataka,Akiba, Kin-Ya
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p. 12195 - 12202
(2007/10/03)
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- Palladium-catalyzed suzuki-type self-coupling of arylboronic acids. A mechanistic study
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Symmetrical biaryls are formed from arylboronic acids both under tetrakis(triphenylphosphine)-palladium and under palladium(II) acetate catalysis. The principal mechanistic features of these self-couplings have been determined.
- Moreno-Manas, Marcial,Perez, Montserrat,Pleixats, Roser
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p. 2346 - 2351
(2007/10/03)
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