- Boronic acid-based bipyridinium salts as tunable receptors for monosaccharides and α-hydroxycarboxylates
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Several novel diboronic acid-substituted bipyridinium salts were prepared and, using a fluorescent reporter dye, were tested for their ability to selectively bind various monosaccharides and α-hydroxycarboxylates in an aqueous medium. The fluorescence sensing mechanism relies on the formation of a ground-state charge-transfer complex between the dye and bipyridinium. An X-ray crystal structure of this complex is described herein. Glucose selectivity over fructose and galactose was achieved by designing the bipyridinium-based receptors to be capable of attaining a 1:1 receptor/substrate stoichiometry via cooperative diboronic acid binding.
- Gamsey, Soya,Miller, Aaron,Olmstead, Marilyn M.,Beavers, Christine M.,Hirayama, Lacie C.,Pradhan, Sulolit,Wessling, Ritchie A.,Singaram, Bakthan
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- Iron(ii) thio- and selenocyanate coordination networks containing 3,3′-bipyridine
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A number of different compounds have been synthesised by reaction of solutions containing Fe(NCE)2 (E = S, Se) with solutions containing 3,3′-bipyridine. When the solvent used is methanol, the products are the monomeric compounds trans-{Fe(NCS)2(3,3′-bipy) 2(MeOH)2} 1 or trans-{Fe(NCSe)2(3,3′- bipy)2(MeOH)2} 2, but when acetonitrile is used the layered coordination network {Fe(NCS)2(3,3′-bipy)2} 3 or doubly interpenetrated coordination network {Fe(NCSe)2(3, 3′-bipy)2} 4 is formed instead. Using methanol to dissolve the Fe(NCE)2 and CHX3 (X = Cl, Br) to dissolve the 3,3′-bipyridine yields solvated coordination networks of stoichiometry {Fe(NCE)2(3,3′-bipy)2}·2CHX3. The crystal structures of all of these compounds except 4 are presented.
- Adams, Christopher J.,Haddow, Mairi F.,Harding, David J.,Podesta, Thomas J.,Waddington, Rachel E.
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- Photon-Induced Reactions of Aromatics Adsorbed on Rough and Smooth Silver Surfaces
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We have investigated the thermal and photon-induced chemistry of several aromatics adsorbed on smooth and roughtened Ag(111) surfaces at low temperatures (110 K).Pyrazine, pyridine, 3-chloropyridine, and chlorobenzene quantitatively desorb from Ag(111) near 200 K.After roughtening the surface with 2 kV Ar ion bombardment, the breadth of the molecular desorption curves increases, and there is a high-temperature tail due to desorption from defecty sites produced by the roughening process.Upon UV photolysis of 1 monolayer, chlorobenzene and 3-chloropyridine photodissociate on smooth and rough Ag surfaces, whereas no detectable photoreaction were observed for pyrazine or pyridine absorbed on either surface.For the molecules that did not undergo photodissociation, a shift to lower energy in the photodissociation threshold was observed on the rough surface relative to the smooth: 3.3 eV versus 3.5 eV for chlorobenzene and 3.5 eV versus 3.9 eV for 3-chloropyridine.We postulate that the decrease in the photodissociation threshold is due to defect sites produced by surface roughening, through either excitation of the surface plasmon resonance, which is allowed on the rough but not the smooth surface, or a more localized excitation near defect sites.Excitation in the molecular absorption band shows that the photodissociation yield is enhanced for 3-chloropyridine and quenched for chlorobenzene on the rough surface relative to the smooth.Theoretical calculations suggest that there is a decrease in the decay rate for 3-chloropyridine and an increase in the decay rate for chlorobenzene on the rough surface compared to smooth.Differences between the quenching rates for 3-chloropyridine and chlorobenzene may be related to the different molecular orientations of these two molecules on the surface.
- Myli, K. B.,Coon, S. R.,Grassian, V. H.
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- Effect of Surface Roughness on the Photodissociation Threshold of Chlorobenzene and 3-Chloropyridine Adsorbed on Silver
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We have investigated the photodissociation of chlorobenzene and 3-chloropyridine adsorbed on smooth and rough Ag surfaces.Photolysis of adsorbed chlorobenzene and 3-chloropyridine with UV radiation results in C-Cl bond dissociation.Biphenyl and bipyridyl desorb from the surface near 400 K, and AgCl desorbs near 800 K in postirradiation temperature-programmed desorption.Compared to a smooth surface, there is a red shift in the photodissociation threshold for both molecules when adsorbed on a rough surface.Possible mechanisms for the red shift are discussed.This study demonstrates the importance of substrate morphology on surface photochemistry.
- Myli, K. B.,Grassian, V. H.
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- Fluorinated Boronic Acid-Appended Bipyridinium Salts for Diol Recognition and Discrimination via 19F NMR Barcodes
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Fluorinated boronic acid-appended benzyl bipyridinium salts, derived from 4,4′-, 3,4′-, and 3,3′-bipyridines, were synthesized and used to detect and differentiate diol-containing analytes at physiological conditions via 19F NMR spectroscopy. An array of three water-soluble boronic acid receptors in combination with 19F NMR spectroscopy discriminates nine diol-containing bioanalytescatechol, dopamine, fructose, glucose, glucose-1-phosphate, glucose-6-phosphate, galactose, lactose, and sucroseat low mM concentrations. Characteristic 19F NMR fingerprints are interpreted as two-dimensional barcodes without the need of multivariate analysis techniques.
- Axthelm, J?rg,G?rls, Helmar,Schubert, Ulrich S.,Schiller, Alexander
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- Photoinduced Regioselective Olefination of Arenes at Proximal and Distal Sites
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The Fujiwara-Moritani reaction has had a profound contribution in the emergence of contemporary C-H activation protocols. Despite the applicability of the traditional approach in different fields, the associated reactivity and regioselectivity issues had
- Ali, Wajid,Anjana, S. S.,Bhattacharya, Trisha,Chandrashekar, Hediyala B.,Goswami, Nupur,Guin, Srimanta,Maiti, Debabrata,Panda, Sanjib,Prakash, Gaurav,Saha, Argha,Sasmal, Sheuli,Sinha, Soumya Kumar
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supporting information
p. 1929 - 1940
(2022/02/01)
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- A General, Multimetallic Cross-Ullmann Biheteroaryl Synthesis from Heteroaryl Halides and Heteroaryl Triflates
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Despite their importance to medicine and materials science, the synthesis of biheteroaryls by cross-coupling remains challenging. We describe here a new, general approach to biheteroaryls: the Ni-and Pd-catalyzed multimetallic cross-Ullmann coupling of he
- Dibenedetto, Tarah A.,Kang, Kai,Loud, Nathan L.,Weix, Daniel J.
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supporting information
p. 21484 - 21491
(2022/01/03)
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- Porphyrin n-pincer pd(Ii)-complexes in water: A base-free and nature-inspired protocol for the oxidative self-coupling of potassium aryltrifluoroborates in open-air
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Metalloporphyrins (and porphyrins) are well known as pigments of life in nature, since representatives of this group include chlorophylls (Mg-porphyrins) and heme (Fe-porphyrins). Hence, the construction of chemistry based on these substances can be based on the imitation of biological systems. Inspired by nature, in this article we present the preparation of five different porphyrin, meso-tetraphenylporphyrin (TPP), meso-tetra(p-anisyl)porphyrin (TpAP), tetra-sodium meso-tetra(p-sulfonatophenyl)porphyrin (TSTpSPP), meso-tetra(m-hydroxyphenyl)porphyrin (TmHPP), and meso-tetra(m-carboxyphenyl)porphyrin (TmCPP) as well as their N-pincer Pd(II)-complexes such as Pd(II)-meso-tetraphenylporphyrin (PdTPP), Pd(II)-meso-tetra(p-anisyl)porphyrin (PdTpAP), Pd(II)-tetrasodium meso-tetra(p-sulfonatophenyl)porphyrin (PdTSTpSPP), Pd(II)-meso-tetra(m-hydroxyphenyl)porphyrin (PdTmHPP), and Pd(II)-meso-tetra(m-carboxyphenyl)porphyrin (PdTmCPP). These porphyrin N-pincer Pd(II)-complexes were studied and found to be effective in the base-free self-coupling reactions of potassium aryltrifluoroborates (PATFBs) in water at ambient conditions. The catalysts and the products (symmetrical biaryls) were characterized using their spectral data. The high yields of the biaryls, the bio-mimicking conditions, good substrate feasibility, evading the use of base, easy preparation and handling of catalysts, and the application of aqueous media, all make this protocol very attractive from a sustainability and cost-effective standpoint.
- Hanafiah, Marlia M.,Lakkaboyana, Sivarama Krishna,Lakshmidevi, Jangam,Marella, Ravi Kumar,Naidu, Bandameeda Ramesh,Prasad, Sana Siva,Venkateswarlu, Katta
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- Tandem Mn–I Exchange and Homocoupling Processes Mediated by a Synergistically Operative Lithium Manganate
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Pairing lithium and manganese(II) to form lithium manganate [Li2Mn(CH2SiMe3)4] enables the efficient direct Mn–I exchange of aryliodides, affording transient (aryl)lithium manganate intermediates which in turn undergo spontaneous C?C homocoupling at room temperature to furnish symmetrical (bis)aryls in good yields under mild reaction conditions. The combination of EPR with X-ray crystallographic studies has revealed the mixed Li/Mn constitution of the organometallic intermediates involved in these reactions, including the homocoupling step which had previously been thought to occur via a single-metal Mn aryl species. These studies show Li and Mn working together in a synergistic manner to facilitate both the Mn–I exchange and the C?C bond-forming steps. Both steps are carefully synchronized, with the concomitant generation of the alkyliodide ICH2SiMe3 during the Mn–I exchange being essential to the aryl homocoupling process, wherein it serves as an in situ generated oxidant.
- Uzelac, Marina,Mastropierro, Pasquale,de Tullio, Marco,Borilovic, Ivana,Tarrés, Màrius,Kennedy, Alan R.,Aromí, Guillem,Hevia, Eva
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supporting information
p. 3247 - 3253
(2020/12/11)
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- Pd-catalyzed oxidative homocoupling of arylboronic acids in WEPA: A sustainable access to symmetrical biaryls under added base and ligand-free ambient conditions
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Symmetrical and unsymmetrical biaryls comprises a diverse class of biologically eloquent organic compounds. We herein report, a quick and eco-friendly protocol for the synthesis of biaryls by an oxidative (aerobic) homocoupling of arylboronic acids (ABAs) using Pd(OAc)2 in water extract of pomogranate ash (WEPA) as an efficient agro-waste(bio)-derived aqueous (basic) media. The reactions were executed at ambient aerobic conditions in the absence of external base and ligand to result symmetrical biaryls in excellent yields. The use of renewable media with an effective exploitation of waste, short reaction times, excellent yields of products, easy separation of the products, unnecessating the external base, oxidant, ligand or volatile organic solvents and ambient reaction conditions are the vital insights of the present protocol.
- Appa, Rama Moorthy,Lakshmidevi, Jangam,Naidu, Bandameeda Ramesh,Venkateswarlu, Katta
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- Synthesis of 3-aryl-1-phosphinoimidazo[1,5-a]pyridine ligands for use in Suzuki-Miyaura cross-coupling reactions
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3-Aryl-1-phosphinoimidazo[1,5-a]pyridine ligands were synthesized from 2-aminomethylpyridine as the initial substrateviatwo complementary routes. The first synthetic pathway underwent the coupling of 2-aminomethylpyridine with substituted benzoyl chlorides, followed by cyclization, iodination and palladium-catalyzed cross-coupling phosphination reactions sequence to give our phosphorus ligands. In the second route, 2-aminomethylpyridine was cyclized with aryl aldehydes, followed by the iodination and palladium-catalyzed cross-coupling phosphination reactions to yield our phosphorus ligands. The 3-aryl-1-phosphinoimidazo[1,5-a]pyridine ligands were evaluated in palladium-catalyzed sterically-hindered biaryl and heterobiaryl Suzuki-Miyaura cross-coupling reactions.
- Dinh, Long P.,Harris, Nekoda W.,Jacoby, Seth A.,Semsey, Rebecca Y.,Swann, William A.,Tran, Ryan Q.,Williamson, Savannah N.,Yet, Larry
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p. 28347 - 28351
(2021/09/15)
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- Glucopyranoside-substituted imidazolium-based chiral ionic liquids for Pd-catalyzed homo-coupling of arylboronic acids in water
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Chiral ionic liquids (CILs) are widely used solvents and materials with prominent properties. Carbohydrate-derived imidazolium-based CILs represent a distinctive type of CILs possessing multiple chiral centers from natural chiral pool. Herein, a series of glucopyranoside-substituted imidazolium-based CILs (Glu-imi-CILs) were synthesized and evaluated as ligands for Pd-catalyzed homo-coupling reactions of arylboronic acids in water. The glucopyranoside substituent was instrumental for improving the catalytic activity of the resulting catalysts. Moreover, a Glu-imi-CIL with a free hydroxyl group for additional coordination was found to be the most efficient ligand. A series of symmetric biaryl compounds (13 examples) were synthesized from arylboronic acids by this method in high isolated yields (85?99percent).
- Huang, Zhiqiang,Kong, Lingfang,Li, Jing,Wu, Yue,Xue, Jun,Yuan, Yangyang,Zhou, Zhonggao
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- Dehydrogenative Synthesis of 2,2′-Bipyridyls through Regioselective Pyridine Dimerization
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2,2′-Bipyridyls have been utilized as indispensable ligands in metal-catalyzed reactions. The most streamlined approach for the synthesis of 2,2′-bipyridyls is the dehydrogenative dimerization of unfunctionalized pyridine. Herein, we report on the palladium-catalyzed dehydrogenative synthesis of 2,2′-bipyridyl derivatives. The Pd catalysis effectively works with an AgI salt as the oxidant in the presence of pivalic acid. A variety of pyridines regioselectively react at the C2-positions. This dimerization method is applicable for challenging substrates such as sterically hindered 3-substituted pyridines, where the pyridines regioselectively react at the C2-position. This reaction enables the concise synthesis of twisted 3,3′-disubstituted-2,2′-bipyridyls as an underdeveloped class of ligands.
- Yamada, Shuya,Kaneda, Takeshi,Steib, Philip,Murakami, Kei,Itami, Kenichiro
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supporting information
p. 8341 - 8345
(2019/04/30)
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- WEPA: a bio-derived medium for added base, π-acid and ligand free Ullmann coupling of aryl halides using Pd(OAc)2
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A bio-derived sustainable medium based on water extract of pomegranate ash (WEPA) has, for the first time, been developed for the homocoupling of aryl halides under palladium-assistance. Avoiding the requirement of an external base, ligand and π-acid, the use of the proposed renewable medium offers remarkable attributes like wide substrate scope, good to nearly quantitative yields of biphenyls with exceptional chemoselectivity and scale up viability.
- Lakshmidevi, Jangam,Appa, Rama Moorthy,Naidu, Bandameeda Ramesh,Prasad, S. Siva,Sarma, Loka Subramanyam,Venkateswarlu, Katta
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supporting information
p. 12333 - 12336
(2018/11/30)
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- The first report on the transition metal-free homocoupling of aryl halides in the presence of l-cysteine
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A green and efficient methodology for the coupling of aryl halides without the addition of a transition metal catalyst has been presented. The biaryl coupling of haloarenes can be promoted by l-cysteine and potassium hydroxide. This is the first report on the synthesis of symmetrical biaryls under transition metal-free conditions.
- Ghorbani-Choghamarani, Arash,Taherinia, Zahra
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supporting information
p. 10989 - 10992
(2018/07/05)
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- Nickel-Catalyzed Electrochemical Reductive Homocouplings of Aryl and Heteroaryl Halides: A Useful Route to Symmetrical Biaryls
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Due to their widespread presence in functional materials and pharmaceuticals, biaryls are of fundamental importance in organic chemistry. Methods for the synthesis of symmetrical biaryls generally involve both metallic reduction and transition-metal catalysis. In this work, we show that electroreduction can also constitute a very relevant way to achieve the nickel-catalyzed reductive synthesis of symmetrical biaryl compounds. Therefore, it is demonstrated that both aryl and heteroaryl halides undergo reductive coupling to furnish the corresponding symmetrical biaryls in fair to excellent yields. Reactions are performed under very mild conditions thus ensuring important functional group tolerance.
- Rahil, Rima,Sengmany, Stéphane,Le Gall, Erwan,Léonel, Eric
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p. 146 - 154
(2017/09/28)
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- Iron-Catalyzed Isopropylation of Electron-Deficient Aryl and Heteroaryl Chlorides
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Traditional methods for the preparation of secondary alkyl-substituted aryl and heteroaryl chlorides challenge both selectivity and functional group tolerance. This contribution describes the use of statistical design of experiments to develop an effective procedure for the preparation of isopropyl-substituted (hetero)arenes with minimal isopropyl to n-propyl isomerization. The reaction tolerates electronically diverse aryl chloride coupling partners, with excellent conversion observed for strongly electron-deficient aromatic rings, such as esters and amides. Electron-rich systems, including methyl- and methoxy-substituted aryl chlorides, were found to be less reactive. Furthermore, the reaction was found to be most successful when heteroaryl chlorides were submitted to the cross-coupling protocol. By mapping substituent effects on reaction selectivity, we were able to show that electron-deficient aryl chlorides are essential for efficient coupling, and use electronic structure calculations to predict the likelihood of successful coupling through the estimation of the electron affinity of each aryl chloride. Moderate isolated yields were achieved with selected aryl chlorides, and moderate to good isolated yields were obtained for all the heteroaryl chlorides coupled. Excellent selectivity was observed when a 2,6-dichloroquinoline was used, allowing mono-substitution on a challenging substrate. (Figure presented.).
- Sanderson, James N.,Dominey, Andrew P.,Percy, Jonathan M.
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p. 1007 - 1017
(2017/03/27)
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- Copper-free palladium-catalysed desulfinative homocoupling of sodium arylsulfinates under mild and aerobic conditions
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A Pd(II)-catalysed homocoupling of sodium arylsulfinates has been successfully achieved under mild conditions. This transformation is a new method for the homocoupling reaction of sodium arylsulfinates, thus providing an alternative synthesis of symmetric biaryls. The reported homocoupling reaction is tolerant to many common functional groups, such as ester, halo, cyano and nitro and works well in the presence of electron-donating and electron-withdrawing substituents. Notably, the reported desulfinative homocoupling does not require Cu salts, ligands and bases, making this newly developed transformation attractive.
- Zhang, Wei
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- Palladium-catalyzed reductive homocoupling of aryl sulfonates via cleavage of C─O bond at room temperature
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Palladium-catalyzed reductive homocoupling of aryl sulfonates has been successfully achieved under mild conditions. This transformation is a new method for the homocoupling reaction of aryl sulfonates at room temperature via the cleavage of C─O bonds, thus providing an alternative synthesis of symmetric biaryls. The reported reductive homocoupling reaction is tolerant of many common functional groups regardless of electron-donating or electron-withdrawing nature, making this newly developed transformation important for complementing Ullmann coupling. Experimental Section. Typical procedure for the products.
- Zhong, Shuangling,Chen, Mengxin,Liu, Ge,Sun, Chenggang,Liu, Wencong
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- Sequential one pot double C[sbnd]H heteroarylation of thiophene using bromopyridines to synthesize unsymmetrical 2,5-bipyridylthiophenes
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We present C[sbnd]H heteroarylation reactions between thiophene and variously substituted bromopyridines. The objective was to synthesize unsymmetrical 2,5-bipyridylthiophenes. We studied the reaction conditions allowing to a sequential one-pot double C[sbnd]H heteroarylation, in a view to introduce two different pyridyl moieties at positions 2 and 5 of the thiophene ring using bromopyridines. 11 original unsymmetrical 2,5-bipyridylthiophenes were synthesized and characterized, including 2,5-di(pyridin-2-yl)thiophenes for which the preparation by classical cross-coupling reactions is challenging. Finally, with the additional synthesis of both an unsymmetrical 2,5-biarylthiophene and an original pyrimidin-thiophene-furan scaffold, we shown that our methodology was also an efficient tool to access to new heterocyclic sequences.
- Kieffer, Charline,Babin, Victor,Jouanne, Marie,Slimani, Ikram,Berhault, Yohann,Legay, Rémi,Sopková-de Oliveira Santos, Jana,Rault, Sylvain,Voisin-Chiret, Anne Sophie
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p. 5509 - 5516
(2017/08/22)
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- Pd(II)-Catalyzed C3-Selective Arylation of Pyridine with (Hetero)arenes
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Palladium catalyzed, nondirected C3-selective arylation of pyridines with arenes and heteroarenes in the presence of 1,10-phenanthroline as the ligand has been developed. The optimized conditions allow for a highly C3-selective arylation of pyridines, affording various 3,3′-bipyridines and 3-arylpyridines. (Chemical Equation Presented).
- Gao, Guo-Lin,Xia, Wujiong,Jain, Pankaj,Yu, Jin-Quan
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supporting information
p. 744 - 747
(2016/03/01)
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- Homocoupling of heteroaryl/aryl/alkyl Grignard reagents: I2-promoted, or Ni- or Pd- or Cu- or nano-Fe-based salt catalyzed
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Five efficient processes for the homo-coupling of various Grignard reagents including aryl, heteroaryl and aliphatic ones in the presence of I2, Pd(OAc)2, Ni(OAc)2, CuI, and nano-Fe3O4 were developed, respectively.
- Li, Xing,Li, Dongjun,Li, Yingjun,Chang, Honghong,Gao, Wenchao,Wei, Wenlong
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p. 86998 - 87002
(2016/09/23)
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- Carboxyamido/carbene ligated palladium (II) complex: A versatile catalyst for the synthesis of aryl-substituted heteroarenes
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Carboxy amido/carbene ligated Pd-complex catalyzed Suzuki-Miyaura cross-coupling of aryl-boronic acids with heteroaryl bromides is described. The protocol has a broad substrate scope that includes electron-rich, electron-deficient and sterically hindered arylboronic acids and heteroaryl bromides. The catalytic activity of the catalyst has been further investigated in the coupling of 2,6-dibromopyridine with arylboronic acids.
- Vishnuvardhan Reddy, Police,Parsharamulu, Thupakula,Annapurna, Manne,Likhar, Pravin R.,Kantam, Mannepalli Lakshmi,Bhargava, Suresh
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supporting information
p. 150 - 153
(2016/12/06)
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- Palladium-catalyzed decarboxylative cross-coupling of 3-pyridyl and 4-pyridyl carboxylates with aryl bromides
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Decarboxylative cross-coupling of 3-pyridyl and 4-pyridyl carboxylates with aryl bromides is reported. Using a bimetallic system of Cu2O and Pd(PPh3)4, the scope of the reaction is demonstrated by the synthesis of 27 pyridine-containing biaryls in moderate to good yields.
- Chennamaneni, Lohitha Rao,William, Anthony D.,Johannes, Charles W.
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p. 1293 - 1296
(2015/03/04)
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- Efficient phosphine ligands for the one-pot palladium-catalyzed borylation/Suzuki-Miyaura cross-coupling reaction
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We report the synthesis of 2-(anthracen-9-yl)-1H-inden-3-yl dicyclohexylphosphine and its use in palladium-catalyzed borylation/Suzuki-Miyaura cross-coupling reaction to prepare a variety of symmetrical and unsymmetrical biaryl compounds in excellent yield. This journal is
- Chen, You,Peng, Hui,Pi, Yun-Xiao,Meng, Tong,Lian, Ze-Yu,Yan, Meng-Qi,Liu, Yan,Liu, Sheng-Hua,Yu, Guang-Ao
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supporting information
p. 3236 - 3242
(2015/03/18)
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- Three-coordinate copper(I) 2-hydroxy-1,10-phenanthroline dinuclear complex catalyzed homocoupling of arylboronic acids towards biphenyls under air condition
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An efficient synthesis of biphenyls via three-coordinate planar dinuclear Cu2(ophen)2 complex catalyzed homocoupling of arylboronic acids under air condition and in the condition of alkali-free was demonstrated. Uniquely, this catalyst shows high selectivity towards biphenyls when the reaction was conducted in aqueous solution, which is significantly different from selectivity towards phenols in related Cu-catalysts. Utilization of environmentally friendly water as main solvent, reaction at room temperature and in the absence of base, cheapness, low loading and easy bulk preparation of catalyst make it potential in green synthesis of biphenyls.
- Wang, Yan-Hong,Xu, Mei-Chen,Liu, Jie,Zhang, Ling-Juan,Zhang, Xian-Ming
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p. 9598 - 9601
(2015/12/04)
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- Nickel-catalyzed one-pot deoxygenation and reductive homocoupling of phenols via C-O activation using TCT reagent
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A new method for C-O bond activation of phenolic compounds has been achieved using 2,4,6-trichloro-1,3,5-triazine to utilize in one-pot Ni-catalyzed deoxygenation and reductive homocoupling reactions. With this simple method, phenolic compounds were converted to their corresponding arenes or biaryl compounds under mild conditions. The introduced methodology has a broad scope and demonstrates good functional group compatibility.
- Iranpoor, Nasser,Panahi, Farhad
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supporting information
p. 214 - 217
(2015/01/30)
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- N-Heterocyclic Carbene-Pd Polymers as Reusable Precatalysts for Cyanation and Ullmann Homocoupling of Aryl Halides: The Role of Solvent in Product Distribution
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A main-chain N-heterocyclic carbene (NHC) polymer with N-dodecyl-substituted groups was found to be a highly efficient precatalyst for cyanation of various aryl halides by using nontoxic cyanic source [K4Fe(CN)6] under relatively mild reaction conditions. Several aryl iodides, bromides, and activated chlorides were successfully converted to their corresponding benzonitrile derivatives without using additives (such as reducing agents or exogenous organic ligands) in good to excellent yields. Our investigations showed that changing the solvent from DMF to polyethylene glycol (PEG-200) resulted in dramatic decline of cyanation product formation to the benefit of the Ullmann homocoupling reaction. The catalyst could be reused four and five times with only slight loss of activity in cyanation and the Ullmann coupling, respectively.
- Karimi, Babak,Vafaeezadeh, Majid,Akhavan, Pari Fadavi
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p. 2248 - 2254
(2015/11/24)
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- Diphenylphosphorylated PEG (DPPPEG) as a new support for generation of nano-Pd(0) as catalyst for carbon-carbon bond formation via copper-free Sonogashira and homocoupling reactions of aryl halides in PEG
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In this study, synthesis and application of diphenylphosphorylated PEG200 (DPPPEG200) are described. Herein, we report a very simple procedure for the preparation of DPPPEG200 as a stable solid through the reaction of PEG200 with ClPPh2. This compound was used as a very suitable ligand for the in situ generation of nano-Pd(0) particles through its reaction with PdCl2 as a pre-catalyst. Isolation of this catalyst is very simple through addition of diethyl ether to the reaction mixture and centrifugations. Full characterization of the nano-Pd(0)/DPPPEG200 was performed by XRD spectra, UV-Vis spectra, and also by TEM image. This nano-complex was used as an efficient catalyst for copper-free Sonogashira and homocoupling reactions of aryl halides. The sonogashira reaction of aryl halides was conducted at 80 °C in PEG. However, the homocoupling reaction was performed at 100 °C for aryl iodides and activated aryl bromides and at 130 °C for deactivated aryl bromides and aryl chlorides in PEG. The catalyst was recovered and recycled for four consecutive runs.
- Iranpoor, Nasser,Firouzabadi, Habib,Riazi, Asma
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p. 155 - 165
(2015/07/20)
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- Efficient syntheses of [11C]zidovudine and its analogs by convenient one-pot palladium(0)-copper(I) co-mediated rapid C-[ 11C]methylation
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The nucleosides zidovudine (AZT), stavudine (d4T), and telbivudine (LdT) are approved for use in the treatment of human immunodeficiency virus (HIV) and hepatitis B virus (HBV) infections. To promote positron emission tomography (PET) imaging studies on their pharmacokinetics, pharmacodynamics, and applications in cancer diagnosis, a convenient one-pot method for Pd(0)-Cu(I) co-mediated rapid C-C coupling of [11C]methyl iodide with stannyl precursor was successfully established and applied to synthesize the PET tracers [11C]zidovudine, [11C]stavudine, and [ 11C]telbivudine. After HPLC purification and radiopharmaceutical formulation, the desired PET tracers were obtained with high radioactivity (6.4-7.0 GBq) and specific radioactivity (74-147 GBq/μmol) and with high chemical (>99%) and radiochemical (>99.5%) purities. This one-pot Pd(0)-Cu(I) co-mediated rapid C-[11C]methylation also worked well for syntheses of [methyl-11C]thymidine and [methyl-11C]4?- thiothymidine, resulting twice the radioactivity of those prepared by a previous two-pot method. The mechanism of one-pot Pd(0)-Cu(I) co-mediated rapid C-[ 11C]methylation was also discussed. A convenient one-pot method for Pd(0)-Cu(I) co-mediated rapid C-C coupling of [11C]methyl iodide with stannyl precursor was successfully established. Using this method, three antiviral agents were efficiently labeled with 11C to generate the positron emission tomography tracers [11C]zidovudine, [ 11C]stavudine, and [11C]telbivudine. In addition, syntheses of [methyl-11C]thymidine and [methyl-11C]4?- thiothymidine were greatly improved, resulting nearly twice the radioactivity of those obtained by a previous two-pot method. The radiochemical yields (decay-corrected from [11C]carbon dioxide) of these probes reach 53-75%. Copyright
- Zhang, Zhouen,Doi, Hisashi,Koyama, Hiroko,Watanabe, Yasuyoshi,Suzuki, Masaaki
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p. 540 - 549
(2014/08/05)
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- Selective palladium-catalyzed direct C-H arylation of unsubstituted N-protected pyrazoles
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A highly selective C-5 arylation of N-dimethylaminosulfamoyl-protected pyrazole with aryl bromides is catalyzed by 2-5 mol% palladium in the presence of triphenylphosphine ligand and carboxylic acid additive. Selectivities up to 45:1 (C-5:C-4) can be achieved by running the reaction in non-polar solvents. A thorough study of scope and limitations shows good general tolerance of aryl bromide substitution. However, limitations on tolerance of ortho-subsitution and protic functional groups were established. Together with a telescoped deprotection step this method presents a viable alternative for the synthesis of C-3 arylated pyrazole building blocks.
- Kumpulainen, Esa T. T.,Pohjakallio, Antti
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p. 1555 - 1561
(2014/06/09)
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- Palladium on ionic liquid derived nanofibrillated mesoporous carbon: A recyclable catalyst for the ullmann homocoupling reactions of aryl halides in water
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Palladium nanoparticles supported on nanofibrillated mesoporous carbon (Pd@IFMC) were found to be highly active in heterogeneous catalysis for the Ullmann homocoupling of a broad range of aryl chlorides, bromides and iodides in aqueous medium without the need to any chemical co-reducing agents. The catalysts could be recovered and reused several times without significant loss of activity. Giving Ullmann fibrillations: Palladium nanoparticles supported on an ionic-liquid-derived nanofibrillated mesoporous carbon are highly active in catalyzing the Ullmann homocoupling of a range of aryl chlorides, bromides, iodides, and heteroaryl bromides in aqueous medium without the need for chemical co-reducing agents. The catalysts are recovered and reused several times without significant loss of activity.
- Karimi, Babak,Behzadnia, Hesam,Vali, Hojatollah
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p. 745 - 748
(2014/03/21)
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- Bimetallic gold-palladium alloy nanoclusters: An effective catalyst for Ullmann coupling of chloropyridines under ambient conditions
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An efficient method for the Ullmann coupling of chloropyridines catalyzed by poly(N-vinylpyrrolidone) (PVP)-stabilized bimetallic Au-Pd alloy nanoclusters (NCs) under ambient conditions is demonstrated. The reaction does not occur with either gold or palladium single-metal clusters alone, nor with a physical mixture of the two metals. The experimental results indicate that the inclusion of Au as a nearest heteroatom is crucial to initiate the coupling and its composition up to 50% is essential to accelerate the reaction. Unlike the conventional transition metal catalysis, 2-chloropyridine was found to be highly reactive as compared to 2-bromopyridine. From the UV-vis and ICP-AES measurements, a significant amount of leached Pd(ii) was observed in the coupling with 2-bromopyridine as compared with 2-chloropyridine, indicating that the leaching process might be a crucial factor in diminishing the reactivity.
- Dhital, Raghu Nath,Kamonsatikul, Choavarit,Somsook, Ekasith,Sakurai, Hidehiro
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p. 3030 - 3035
(2013/11/06)
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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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supporting information
p. 5378 - 5381
(2013/11/06)
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- Amine-bridged bis(phenol) ligands for efficient Pd-catalyzed aqueous C-C coupling reactions
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The influence of ring size (5 or 6), chain length (1, 2 or 3) and bulkiness of N-aryl substituents in amine-bridged bis(phenol) ligands (1, 2, 3) on palladium-catalyzed aqueous C-C coupling reactions were revealed. The homocoupling of arylboronic acid can be completed in neat water with the aid of a catalytic amount of p-toluenesulfonyl chloride (TsCl) in a very short time under anaerobic or aerobic conditions. Interestingly, the same catalytic system was efficient for Suzuki-Miyaura reaction in aqueous acetone under aerobic conditions in the absence of TsCl. The crystal structures of ligand 1 and three unsymmetrical fluorine-substituted biaryl derivatives were also reported. Copyright
- Zhou, Zhonggao,Liu, Minyan,Wu, Xiaoli,Yu, Hongwei,Xu, Guohai,Xie, Yongrong
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p. 562 - 569
(2013/10/21)
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- Organic synthesis via magnetic attraction: Benign and sustainable protocols using magnetic nanoferrites
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Magnetic nano-catalysts have been prepared using simple modification of iron ferrites. The nm size range of these particles facilitates the catalysis process, as an increased surface area is available for the reaction; the easy separation of the catalysts by an external magnet and their recovery and reuse are additional beneficial attributes. Glutathione bearing nano-ferrites have been used as organocatalysts for the Paal-Knorr reaction and homocoupling of boronic acids. Nanoferrites, post-synthetically modified by ligands, were used to immobilize nanometals (Cu, Pd, Ru, etc.) which enabled the development of efficient, sustainable and green procedures for azide-alkynes-cycloaddition (AAC) reactions, C-S coupling, O-allylation of phenol, Heck-type reactions and hydration of nitriles.
- Nasir Baig,Varma, Rajender S.
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p. 398 - 417
(2013/03/14)
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- Tetraphosphine/palladium-catalyzed Suzuki-Miyaura coupling of heteroaryl halides with 3-pyridine- and 3-thiopheneboronic acid: An efficient catalyst for the formation of biheteroaryls
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An easily prepared tetraphosphine N,N,N′,N′- tetra(diphenylphosphinomethyl)-1,2-ethylenediamine (L1) associated with [Pd(η3-C3H5)Cl]2 affords an efficient catalyst for Suzuki-Miyaura coupling of 3-pyridineboronic acid with heteroaryl bromides. Reaction could be performed with as little as 0.02 mol% catalyst and a high turnover number of 2500 is obtained. A wide range of substrates is investigated with satisfactory yields, and good compatibility with aminogroup-substituted pyridines and unprotected indole is exhibited. This protocol can also be applied successfully to the reaction of heteroaryl bromides with 3-thiopheneboronic acid. This Pd-tetraphosphine catalyst efficiently restrains the poisoning effect from heteroaryls, and shows good stability and longevity. Copyright 2013 John Wiley & Sons, Ltd. An easily prepared tetraphosphine L1 was successfully used in Pd catalyzed Suzuki reaction of heteroaryl bromides with 3-pyridineboronic acid. A high turnover number of 2 500 was achieved and a wide range of heteroaryl halides including aminopyridines and indole was tolerated. With this protocol the coupling of 3-thiopheneboronic acid with heteroaryl bromides could also proceed in good yields. This catalyst system efficiently restrained poisoning effect from heteroaryls, and exhibited good stability and longevity. Copyright
- Wang, Kun,Fu, Qi,Zhou, Rong,Zheng, Xueli,Fu, Haiyan,Chen, Hua,Li, Ruixiang
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p. 232 - 238
(2013/05/08)
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- Microwave assisted suzuki-miyaura and ullmann type homocoupling reactions of 2- and 3-halopyridines using a Pd(OAc)2/benzimidazolium salt and base catalyst system
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A number of novel benzimidazole derivatives 1-4 were synthesized and the catalytic activity of these compounds in a catalytic system consisting of a benzimidazolium salt/Pd(OAc)2/K2CO3 were investigated in the Suzuki-Miyaura and Ullmann type homocoupling reactions under microwave irradiation. We obtained both cross coupling and homocoupling products of pyridine and some side products such as dimethylaminopyridine and unsubstituted pyridine.
- Yilmaz, Uelkue,Deniz, Selma,Kuecuekbay, Hasan,Sireci, Nihat
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p. 3712 - 3724
(2013/06/04)
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- Triazolopyridines. Part 29. Direct arylation reactions with [1,2,3]triazolo[1,5-a]pyridines
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[1,2,3]Triazolo[1,5-a]pyridine reacts with aryl halides in presence of catalytic amounts of Pd(OAc)2 and PPh3 in DMF to give, in medium or low yield, direct arylations in C3 and pyridyl aryl ketones. Thiazole and benzothiazole have been directly arylated using 7-halotriazolopyridines. These behaviours are unprecedented in the chemistry of [1,2,3]triazolo[1,5-a] pyridines. ARKAT-USA, Inc.
- Abarca, Belen,Adam, Rosa,Ballesteros, Rafael,Chiassai, Leonardo,Gamon, Cristina
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p. 229 - 241
(2013/02/25)
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- Metal-free arylation of benzene and pyridine promoted by amino-linked nitrogen heterocyclic carbenes
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An amino-linked nitrogen heterocyclic carbene (amino-NHC), 1-tBu, has been shown to mediate carbon-carbon coupling through the direct C-H functionalization of benzene and pyridine in the absence of a metal catalyst. Using EPR, the first spectroscopic evidence corroborating the single electron transfer mechanism for the metal-free carbon-carbon coupling manifold, as reported by others, is introduced.
- Chen, Wen-Ching,Hsu, Yu-Chen,Shih, Wei-Chun,Lee, Ching-Yu,Chuang, Wen-Han,Tsai, Yi-Fang,Chen, Peter Ping-Yu,Ong, Tiow-Gan
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supporting information; experimental part
p. 6702 - 6704
(2012/07/14)
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- Pd-catalyzed oxidative homocoupling of arylboronic acids in aqueous ethanol at room temperature
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The authors demonstrate for the first time that the Pd(OAc) 2/N,O-ligands act as catalysts toward homocoupling of arylboronic acid in aqueous ethanol (95%) under mild conditions: at room temperature and under aerobic condition. Under the optimal reaction conditions, all reactions gave the homocoupling products in good to excellent yields.
- Zhou, Zhonggao,Hu, Qiaosheng,Du, Ziyi,Xue, Jun,Zhang, Shiyong,Xie, Yongrong
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p. 940 - 943
(2012/11/13)
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- Room-temperature Suzuki-Miyaura coupling of heteroaryl chlorides and tosylates
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Suzuki-Miyaura coupling of heteroaryls is an important method for the preparation of compound libraries for medicinal chemistry and materials research. Although many catalysts have been developed, none of them have been generally applicable to the coupling reactions of heteroaryl chlorides and tosylates at room temperature. We discovered that a catalyst combination of Pd(OAc)2 and XPhos (2-dicyclohexylphosphanyl-2',4',6'- triisopropylbiphenyl) could efficiently catalyze these couplings. Besides the choice of catalyst, the use of hydroxide bases in an aqueous alcoholic solvent was essential for fast couplings. These conditions promoted fast release of active catalyst (XPhos)Pd0, and accelerated the transmetalation in the catalytic cycle. Most of the major families of heteroaryl chlorides (31 examples) and tosylates (17 examples) reached full conversion within minutes to hours at room temperature. The method could be easily scaled up for gram-scale synthesis. Furthermore, we examined the relative reactivity of coupling partners in whole reactions. Electron-rich heteroaryl chlorides and tosylates reacted more slowly than electron-deficient ones, in the order of indole, pyrrole furan, thiophene > pyridine. Similarly, electron-deficient arylboronic acids were less reactive than electron-neutral and electron-rich ones. The reactivity trends from this study can help to choose appropriate coupling partners for Suzuki reactions.
- Yang, Junfeng,Liu, Sijia,Zheng, Jian-Feng,Zhou, Jianrong
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supporting information
p. 6248 - 6259,12
(2020/09/16)
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- General and highly efficient fluorinated-N-heterocyclic carbene-based catalysts for the palladium-catalyzed Suzuki-Miyaura reaction
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A general and highly efficient trifluoromethylated-N-heterocyclic carbene (NHC)-based catalyst for the palladium-catalyzed Suzuki-Miyaura reaction was reported. In the presence of the catalyst, reactions of non-activated aryl chlorides and triflates with aryl boronic acids occurred at room temperature with good to excellent yields (63-98%). In addition, catalysts generated from a combination of Pd(OAc)2/imidazolium salt 6a is not only effective for the coupling of heteroaryl boronic acid with aryl halides and heteroaryl halides, but also efficient for coupling of other heteroaryl halides and heteroaryl boronic acids. Finally, the catalyst is highly effective for Suzuki-Miyaura reaction of aryl bromides and chlorides with 0.01-0.1 mol % loading if the temperature was raised at refluxed THF/H2O.
- Liu, Taoping,Zhao, Xiaoming,Shen, Qilong,Lu, Long
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supporting information; experimental part
p. 6535 - 6547
(2012/08/28)
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- Carboxylate-based, room-temperature ionic liquids as efficient media for palladium-catalyzed homocoupling and sonogashira-hagihara reactions of aryl halides
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Carboxylate-based salts are introduced as easily prepared, cheap and stable ionic liquids (ILs) that act as the base, ligand, reducing agent and media for the efficient phosphane-free, palladium-catalyzed homocoupling reaction of aryl iodides and bromides. The efficient copper and phosphane-free Sonagashira coupling reaction of aryl iodides and bromides is also demonstrated in these ILs. One of the ILs was also phosphorylated and showed high efficiency and recyclability as a medium, and was also used as a ligand for palladium-catalyzed homocoupling and copper-free Sonogashira reactions of aryl iodides and bromides. Copyright
- Iranpoor, Nasser,Firouzabadi, Habib,Ahmadi, Yasaman
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experimental part
p. 305 - 311
(2012/02/03)
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- Microwave-promoted piperidination of halopyridines: A comparison between Ullmann, Buchwald-Hartwig and uncatalysed SNAr reactions
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A comparative study between the most used methodologies for the preparation of piperidinyl pyridines (Buchwald-Hartwig reaction, Ullmann reaction and nucleophilic aromatic substitution (SNAr)) by microwave-assisted piperidination of halopyridines is reported. Our results suggest that the Ullmann reaction is most effective for less reactive halopyridines, while uncatalysed SNAr is sufficient for more reactive ones. Copyright
- Yaunner, Ricardo S.,Barros, Jose C.,Da Silva, Joaquim F. M.
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experimental part
p. 273 - 276
(2012/09/21)
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- Ligand-promoted C3-selective arylation of pyridines with Pd catalysts: Gram-scale synthesis of (±)-preclamol
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The first example of Pd-catalyzed, C3-selective arylation of unprotected pyridines has been developed by employing a catalytic system consisting of Pd(OAc)2 and 1,10-phenanthroline. This protocol provides an expeditious route to an important class of 3-arylpyridines and 3-arylpiperidines frequently found in bioactive compounds. A brief synthesis of the drug molecule (±)-preclamol is also reported.
- Ye, Mengchun,Gao, Guo-Lin,Edmunds, Andrew J. F.,Worthington,Morris, James A.,Yu, Jin-Quan
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supporting information; experimental part
p. 19090 - 19093
(2012/01/07)
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- TBAF-Catalysed silver oxide-mediated cross-coupling of functional trimethysilylpyridines: Access to arylpyridines and bihetaryl compounds
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The concomitant use of silver oxide and catalytic amount of TBAF allowed the efficient and chemoselective coupling of readily available 4-chloro- and 4-methyl-2-trimethyl-silyl-pyridines with heteroaromatic and aromatic halides. Based on control experiments, a mechanism involving the formation of a pyridylsilver intermediate and TBAF recycling is postulated.
- Louerat, Frederic,Tye, Heather,Napier, Spencer,Garrigou, Michael,Whittaker, Mark,Gros, Philippe C.
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experimental part
p. 1768 - 1773
(2011/04/26)
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- Homocoupling of arylboronic acids catalyzed by CuCl in air at room temperature
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Homocoupling of arylboronic acids has been successfully carried out by using the inexpensive simple copper salt CuCl as the catalyst in methanol to obtain symmetric biaryls in good to excellent yields. The reaction proceeds with a CuCl loading of 2 mol-% under extremely mild conditions: in air, at room temperature, without the need of any additives such as base, oxidant, or ligand. A simple and efficient CuCl-catalyzed homocoupling of arylboronic acids for the synthesis of symmetrical biaryls is described. The homocoupling reaction takes place with a catalyst loading of at 2 mol-% in economical and easily handled methanol and under extremely mild conditions: in air, at room temperature, without any additives such as base, oxidant, or ligand. Copyright
- Cheng, Guanjun,Luo, Meiming
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experimental part
p. 2519 - 2523
(2011/06/10)
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- Catalytic homocoupling of aryl, alkenyl, and alkynyl halides with Ni(II)-complexes and zirconocene dichloride
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A new catalytic system (cat. (H)2Phen(Me)2· NiCl2 or (MeO)2Dipyr(H)2·NiCl 2, cat. Zr(cp)2Cl2, 2 equiv Mn, and 2 equiv LiCl) has been developed to facilitate the homocoupling of a wide range of aryl, alkenyl, and alkynyl halides.
- Peng, Jianbiao,Liu, Xiang,Kishi, Yoshito
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experimental part
p. 2172 - 2175
(2011/05/05)
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- Palladium-catalyzed benzoin-mediated redox process leading to biaryls from aryl halides
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An expedient synthetic procedure of biaryl derivatives was developed using a palladium-catalyzed, benzoin-mediated redox process from aryl halides. Various biaryls were synthesized in good yields in short time.
- Park, Bo Ram,Kim, Ko Hoon,Kim, Taek Hyeon,Kim, Jae Nyoung
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scheme or table
p. 4405 - 4407
(2011/09/19)
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- Carbon-carbon bond formation via homocoupling reaction of substrates with a broad diversity in water using Pd(OAc)2 and agarose hydrogel as a bioorganic ligand, support and reductant
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In this study, we have presented a new catalytic system in which Pd(OAc)2 has been used as a pre-catalyst and agarose as a degradable bioorganic ligand, support and reductant for carbon-carbon bond formation via homocoupling reaction of different aryl halides, β-bromo styrene, phenylboronic acid and phenylacetylene as the substrates. The reactions proceeded smoothly with high yields at temperature 100 °C in water without using any organic co-solvent, phosphorus ligand or reducing agents. The catalyst is recyclable and has been recycled for four times with a tiny amount of leaching of Pd into the reaction media. The amount of leaching has been determined by ICP analysis.
- Firouzabadi, Habib,Iranpoor, Nasser,Kazemi, Faezeh
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scheme or table
p. 94 - 99
(2011/11/07)
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- Living nanocatalyst for effective synthesis of symmetrical biaryls
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A convenient procedure is described for the synthesis of symmetrical biaryls via Ullmann coupling reaction catalyzed by palladium nanoparticles stabilized in a polymer matrix. A wide range of aryl halide substrates is transformed into corresponding symmetrical biaryls at a mild reaction condition. Living nature of the nanocatalysts is revealed by in situ recycling methodology and transmission electron microscopy (TEM). Calculation based on density functional theory (DFT) was performed to have better insight on mechanistic cycle and the result was supported by experimental evidence. Preliminary investigation also reveals that these PdNPs act as efficient catalyst in Heck and copper free Sonogashira reactions.
- Santra, Subhankar,Ranjan, Priyadarshi,Mandal, Swadhin K.,Ghorai, Pradip Kr.
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experimental part
p. 47 - 52
(2011/08/03)
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- Magnetically separable nanoferrite-anchored glutathione: Aqueous homocoupling of arylboronic acids under microwave irradiation
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A highly active, stable and magnetically separable glutathione-based organocatalyst provided very good to excellent yields to symmetric biaryls in the homocoupling of arylboronic acids under microwave irradiation.
- Luque, Rafael,Baruwati, Babita,Varma, Rajender S.
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experimental part
p. 1540 - 1543
(2010/11/17)
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