- A palladium catalyst system for the efficient cross-coupling reaction of aryl bromides and chlorides with phenylboronic acid: Synthesis and biological activity evaluation
-
New benzimidazolium salts 1a-c and their palladium bis-N-heterocyclic carbene complexes 2a-c and palladium PEPPSI-type complexes 3a-c were designed, synthesized and structurally characterized by NMR (1H and 13C), IR, DART-TOF mass spectrometry and elemental analysis. Then these complexes 2-3 were employed in the Suzuki-Miyaura cross-coupling reaction of substituted arenes with phenylboronic acid under mild conditions in toluene and DMF/H2O (1/1) to afford functionalized biaryl derivatives in good to excellent yields. The antibacterial activity of palladium bis-N-heterocyclic carbene complexes 2a-c and palladium PEPPSI-type complexes 3a-c was measured by disc diffusion method against Gram positive and Gram negative bacteria. Compounds 2a, 2c and 3a-c exhibited potential antibacterial activity against four bacterial species among the five used indicator cells. The product 2b inhibits the growth of the all five tested microorganisms. Moreover, the antioxidant activity determination of these complexes 2-3, using 2.2-diphenyl-1-picrylhydrazyl (DPPH) as a reagent, showed that compounds 2a-c and 3b possess DPPH antiradical activity. The higher antioxidant activity was obtained from the product 2b which has radical scavenging activity comparable to that of the two used positive controls (gallic acid GA and tutylatedhydroxytoluene BHT ). Investigation of the anti-acetylcholinesterase activity of the studied complexes showed that compounds 2b, 3a, and 3b exhibited moderate activity at 100 μg/mL and product 2b is the most active.
- Lamia, Boubakri,Chakchouk-Mtibaa, Ahlem,Hallouma, Bilel,Mansour, Lamjed,Mellouli, Lotfi,?zdemir, Ismail,Ya?ar, Sedat,Hamdi, Naceur
-
-
Read Online
- Preparation and characterization of PEPPSI-palladium N-heterocyclic carbene complexes using benzimidazolium salts catalyzed Suzuki–Miyaura cross coupling reaction and their antitumor and antimicrobial activities
-
New palladium complexes were efficiently synthesized from the reaction of benzimidazolium salts 2a–e, potassium carbonate (K2CO3) and palladium chloride (PdCl2) in pyridine (for 3a–e). The catalytic activity of these complexes in a catalytic system including palladium complexes and K2CO3 in DMF-H2O was evaluated in Suzuki–Miyaura cross-coupling reactions of aryl bromides and chlorides with phenylboronic acid. Our novel complexes show excellent catalytic activities with high turnover numbers (TON) and high turnover frequencies (TOF) (e.g. for the Suzuki–Miyaura reaction: TON up to 370 and TOF up to 123.3 h?1). Both benzimidazolium salts 2a–e and complexes 3 have been characterized using spectroscopic data and elemental analysis. The antimicrobial activity of the N-heterocyclic carbene palladium complexes 3a–e varies with the nature of the ligands. Also, the IC50 values of both, complexes (3a–e) and benzimidazoles 2a–e, have been determined. In addition, the new palladium complexes were screened for their antitumor activity. Complexes 3e and 3d exhibited the highest antitumor effect with IC50 values 6.85 μg/mL against MCF-7 and 10.75 μg/mL against T47D, respectively.
- Boubakri, Lamia,Dridi, Khaireddine,Al-Ayed, Abdullah Sulaiman,?zdemir, ?smail,Yasar, Sedat,Hamdi, Naceur
-
-
Read Online
- Mechanism of Direct C-H Arylation of Pyridine via a Transient Activator Strategy: A Combined Computational and Experimental Study
-
Recently, we realized the highly selective one-pot synthesis of 2,6-diarylpyridines by using a Pd-catalyzed direct C-H arylation approach via a transient activator strategy. Although methylation reagent as a transient activator and Cu(I) salt or oxide were found to be prerequisites, details regarding the mechanism remained unclear. In this paper, DFT calculations combined with experimental investigations were carried out to elucidate the principle features of this transformation. The results reveal (1) the origin of the exquisite diarylating selectivity of the pyridine under the transient strategy; (2) the possible demethylating reagent as the counteranion of the pyridinium salt; (3) the reason why Cu2O is a better Cu(I) resource than others.
- Jia, Feiyun,Yin, Changzhen,Zeng, Yang,Sun, Rui,Ge, Yi-Cen,Xu, Dingguo,Li, Ruixiang,Chen, Hua,Zhang, Chunchun,Fu, Haiyan
-
-
Read Online
- Enaminones as building blocks in heterocyclic synthesis: A new one pot synthesis of polyfunctional substituted pyridines
-
Enaminones react with a variety of active methyl and methylene reagents in presence of ammonium acetate to yield functionally substituted pyridines in good yields. The reaction proceeded via initial Michael addition across the double bond followed by cyclization. The reaction of enaminone with aromatic aldehyde in acetic acid/ammonium acetate afforded the dihydropyridine that was oxidized to the corresponding pyridine.
- Agamy, Samia Michel,Abdel-Khalik, Mervat Mohammed,Mohamed, Mona Hassan,Elnagdi, Mohammed Hilmy
-
-
Read Online
- Pincerlike manganese complex and preparation method thereof, related ligand and preparation method thereof, catalyst composition and application
-
The invention discloses a pincerlike manganese complex, a preparation method thereof, a ligand for preparation, a preparation method of the ligand, a catalyst composition taking the complex as an active component and application of the catalyst composition. According to the pincerlike manganese complex, a cycloalkyl ring is introduced into a ligand framework, and by regulating and controlling the cyclic tension, flexibility and steric hindrance of the cycloalkyl ring, the reactivity and stability of the manganese metal center can be effectively adjusted, and the catalytic activity and substrate applicability of a manganese metal system are remarkably improved. The catalyst composition taking the pincerlike manganese complex as an active component has the advantages of high catalyst activity, wide substrate application range, mild reaction conditions and the like in the process of preparing quinoline or pyridine derivatives by catalyzing dehydrogenation coupling reaction of o-amino aromatic alcohol or gamma-amino alcohol, ketone or secondary alcohol; and the synthesis advantages of low cost and stable performance are embodied, the operation is simple, and the yield is high.
- -
-
Paragraph 0159-0165
(2021/07/31)
-
- Iron-Catalyzed Ring-Opening Reactions of Cyclopropanols with Alkenes and TBHP: Synthesis of 5-Oxo Peroxides
-
The ring opening of cyclopropanols is rarely used in multicomponent reactions. Herein we report the three-component reaction of cyclopropanols with alkenes and tert-butyl hydroperoxide (TBHP) catalyzed by an iron catalyst. This protocol enables the incorporation of both the β-carbonyl fragment and a peroxy unit across the C=C double bond regioselectively, thus allowing an efficient, facile access to 5-oxo peroxides. Modification of the biologically active molecules and various downstream derivatizations of the peroxides are also demonstrated.
- Lou, Chenhao,Wang, Xin,Lv, Leiyang,Li, Zhiping
-
p. 7608 - 7612
(2021/10/02)
-
- Efficient access to quinolines and quinazolines by ruthenium complexes catalyzed acceptorless dehydrogenative coupling of 2-aminoarylmethanols with ketones and nitriles
-
Treatment of N,N,O-tridentate pyrazolyl-pyridinyl-alcohol ligands, 2-(CR1R2OH)-6-[3,5-(R3)2C3HN2]C5H3N (R1 = R2 = Me, R3 = H (L1H); R1 = Me, R2 = Ph, R3 = H (L2H); R1 = R2 = Ph, R3 = H (L3H); R1 = R2 = R3 = Me (L4H)) with RuCl3?xH2O in refluxing EtOH afforded the corresponding Ru(III) complexes L2RuCl (1a-1d), which were well characterized by IR, HR-MS and X-ray single crystal structural determination. These Ru complexes showed similarly high catalytic performance for both dehydrogenative couplings of 2-aminoarylmethanols with ketones and nitriles, giving the quinolines and quinazolines in good to excellent yields. This protocol provides an atom-economical and sustainable route to access various structurally important quinoline and quinazoline derivatives by using phosphine-free ligand based Ru catalysts.
- Feng, Qi,Han, Zhangang,Hao, Zhiqiang,Huo, Shuaicong,Kong, Siqi,Lin, Jin,Lu, Guo-Liang,Zeng, Guang
-
-
- Ruthenium complex and preparation method thereof and catalytic application
-
The invention discloses a ruthenium complex and a preparation method thereof and catalytic application. The ruthenium complex is reported for the first time. Research finds that the ruthenium complexhas the activity of catalytically synthesizing quinazoline and derivatives thereof or catalytically synthesizing quinoline and derivatives thereof. When the ruthenium complex provided by the inventionis used for catalytic synthesis of quinazoline and derivatives thereof or quinoline and derivatives thereof, the ruthenium complex has the advantages of mild reaction conditions, wide substrate range, high catalytic product yield and good functional group tolerance, and is significantly superior to the prior art.
- -
-
Paragraph 0104-0106; 0145-0146
(2021/01/24)
-
- Direct synthesis of ring-fused quinolines and pyridines catalyzed byNNHY-ligated manganese complexes (Y = NR2or SR)
-
Four cationic manganese(i) complexes, [(fac-NNHN)Mn(CO)3]Br (Mn-1-Mn-3) and [(fac-NNHS)Mn(CO)3]Br (Mn-4) (whereNNHis a 5,6,7,8-tetrahydro-8-quinolinamine moiety), have been synthesized and evaluated as catalysts for the direct synthesis of quinolines and pyridines by the reaction of a γ-amino alcohol with a ketone or secondary alcohol;NNHS-ligatedMn-4proved the most effective of the four catalysts. The reactions proceeded well in the presence of catalyst loadings in the range 0.5-5.0 mol% and tolerated diverse functional groups such as alkyl, cycloalkyl, alkoxy, chloride and hetero-aryl. A mechanism involving acceptorless dehydrogenation coupling (ADC) has been proposed on the basis of DFT calculations and experimental evidence. Significantly, this manganese-based catalytic protocol provides a promising green and environmentally friendly route to a wide range of synthetically important substituted monocyclic, bicyclic as well as tricyclicN-heterocycles (including 50 quinoline and 26 pyridine examples) with isolated yields of up to 93%.
- Han, Mingyang,Lin, Qing,Liu, Qingbin,Liu, Song,Ma, Ning,Solan, Gregory A.,Sun, Wen-Hua,Wang, Zheng,Yan, Xiuli
-
p. 8026 - 8036
(2021/12/27)
-
- Syntheses of Pyrroles, Pyridines, and Ketonitriles via Catalytic Carbopalladation of Dinitriles
-
The first example of the Pd-catalyzed addition of organoboron reagents to dinitriles, as an efficient means of preparing 2,5-diarylpyrroles and 2,6-diarylpyridines, has been discussed here. Furthermore, the highly selective carbopalladation of dinitriles with organoboron reagents to give long-chain ketonitriles has been developed as well. Based on the broad scope of substrates, excellent functional group tolerance, and use of commercially available substrates, the Pd-catalyzed addition reaction of arylboronic acid and dinitriles is expected to be significant in future synthetic procedures.
- Qi, Linjun,Li, Renhao,Yao, Xinrong,Zhen, Qianqian,Ye, Pengqing,Shao, Yinlin,Chen, Jiuxi
-
supporting information
p. 1097 - 1108
(2020/01/22)
-
- Palladium (II) Complexes Containing 2-Phenylpyridine Derivatives: Synthesis, Molecular Structures, and Catalytic Activity for Suzuki–Miyaura Cross-Coupling Reactions
-
The preparation and characterization of a series of new 2-phenylpyridine derivative ligands consisting of 2-(R) pyridine (R = mesityl (L1), 2,6-dimethylphenyl (L2), o-tolyl (L3), m-tolyl (L4), p-tolyl (L5), o-methoxyphenyl (L6), and p-methoxyphenyl (L7)) and their Pd complexes [PdCl2L2] (L1–L7) is investigated using a combination of X-ray diffraction spectroscopy, GC-MS, and NMR. The crystal structures show that the Pd complexes adopt a square planar geometry, and the monodentate ligand is coordinated through the N donor of the pyridine ring to the Pd atom. The catalytic activities of the synthesized complexes are investigated. The square planar Pd complex trans-[(2-mesitylpy)2PdCl2)] shows a high efficiency in promoting Suzuki-Miyaura cross coupling in an aqueous solvent under aerobic conditions.
- Adamson, A.,Alhaddad, M. R.,Arshad, M. N.,Asiri, A. M.,Budiman, Y. P.,Mkhalid, I.,Muhammad, R.
-
p. 466 - 475
(2020/07/31)
-
- Influence of Ligand and Nuclearity on the Cytotoxicity of Cyclometallated C^N^C Platinum(II) Complexes
-
A series of cyclometallated mono- and di-nuclear platinum(II) complexes and the parent organic ligand, 2,6-diphenylpyridine 1 (HC^N^CH), have been synthesized and characterized. This library of compounds includes [(C^N^C)PtII(L)] (L=dimethylsulfoxide (DMSO) 2 and triphenylphosphine (PPh3) 3) and [((C^N^C)PtII)2(L‘)] (where L‘=N-heterocycles (pyrazine (pyr) 4, 4,4‘-bipyridine (4,4‘-bipy) 5 or diphosphine (1,4-bis(diphenylphosphino)butane (dppb) 6). Their cytotoxicity was assessed against four cancerous cell lines and one normal cell line, with results highlighting significantly increased antiproliferative activity for the dinuclear complexes (4–6), when compared to the mononucleated species (2 and 3). Complex 6 is the most promising candidate, displaying very high selectivity towards cancerous cells, with selectivity index (SI) values >29.5 (A2780) and >11.2 (A2780cisR), and outperforming cisplatin by >4-fold and >18-fold, respectively.
- Kergreis, Angélique,Lord, Rianne M.,Pike, Sarah J.
-
p. 14938 - 14946
(2020/10/19)
-
- Cyclometalated pt complexes of cnc pincer ligands: Luminescence and cytotoxic evaluation
-
In the framework of our attempts to develop cyclometalated Pt(II) complexes toward bifunctional targeting inhibitors or agents for photodynamic therapy, diagnostics, and bioimaging, a series of bis-cyclometalated Pt(II) complexes [Pt(CNC)(L)] (L = DMSO, MeCN) containing various (CNC)2- ligands based on 2,6-diphenylpyridine were synthesized and characterized analytically and spectroscopically, focusing on their electrochemical, luminescence, and antiproliferative properties. Electrochemical experiments and UV-vis absorption spectroscopy suggest ligand-centered LUMOs and metal-centered HOMOs in line with DFT calculations. Extension of the ancillary phenyl to naphthyl cores and a central 4-phenylpyridine group instead of pyridine results in bathochromic shifts of the long-wavelength absorption bands ranging from 420 to 440 nm, with the latter shift being more pronounced. The complexes of the fused CNC heterocyclic systems dba (H2dba = dibenzo[c,h]acridine), db(ph)a (H2db(ph)a = 7-phenyldibenzo[c,h]acridine), and bzqph (HbzqphH = 2-phenylbenzo[h]quinoline) absorb far more red-shifted in the range 500-530 nm. All complexes show reversible first electrochemical reductions and irreversible oxidations with an electrochemical gap of about 3 V, roughly in line with the absorption energies. While the 2,6-diphenylpyridine complexes [Pt(CNC)(DMSO)] show no luminescence at ambient temperature in solution, the fused dba, db(ph)a, and bzqph derivatives are efficient triplet emitters at ambient temperature with emission wavelengths in the region 575-600 nm and quantum yields ranging from 7 to 23%. Vibrationally resolved emission spectra calculated in the framework of DFT faithfully reproduce the experimental data. TD-DFT calculations at the excited-state T1 geometry reveal intraligand π-π*/MLCT character of the emission for all three investigated complexes. Antiproliferative tests on selected complexes gave very different toxicities, ranging from lower than 1 μM to virtually nontoxic. The data allowed drawing some structure-activity relationships (SAR), even though variations in solubility could also significantly account for the different toxicities.
- Garbe, Simon,Krause, Maren,Klimpel, Annika,Neundorf, Ines,Lippmann, Petra,Ott, Ingo,Brünink, Dana,Strassert, Cristian A.,Doltsinis, Nikos L.,Klein, Axel
-
supporting information
p. 746 - 756
(2020/03/30)
-
- Palladium-Catalyzed Cascade Reactions of I-Ketonitriles with Arylboronic Acids: Synthesis of Pyridines
-
This study presents the first example of the Pd-catalyzed cascade reactions of 5-oxohexanenitrile with arylboronic acids, affording important synthon 2-methylpyridines that can be further translated through C(sp3)-H functionalization to construct pyridine derivatives. Furthermore, this chemistry allows 5-oxo-5-Arylpentanenitrile to react with arylboronic acids to provide unsymmetrical 2,6-diarylpyridines. This protocol paves the way for the practical and atom economical syntheses of valuable pyridines with broad functional groups in moderate to excellent yields under mild conditions.
- Chen, Jiuxi,Hu, Maolin,Li, Renhao,Liu, Jichao,Qi, Linjun,Shao, Yinlin,Yao, Xinrong,Zhao, Zhiwei,Zhen, Qianqian
-
p. 114 - 119
(2020/03/25)
-
- Diarylpyridine substance and 2,6- preparation method thereof (by machine translation)
-
The method disclosed by the invention is 2,6 - characterized in that the; reaction time of the, reaction 5 - of the palladium catalyst and the acid promoter is 12 - 24 that the reaction time of the reaction process. of the; palladium catalyst and the (acid promoter is, that) the (reaction time of the) reaction process ; of the palladium catalyst and the; acid promoter is 80 - 100 °C, the reaction time of, the reaction, 96%, 2,6 . (by machine translation)
- -
-
Paragraph 0026-0032; 0095-0102
(2020/01/25)
-
- Decarboxylative cyclization of amino acids towards the Regioselective synthesis of 2,4-diarylpyridines via relay Fe(III)/In(III)-catalysis
-
A competent relay Fe(III)-/In(III)-catalyzed decarboxylative cyclization of amino acids has been devised towards the exclusive preparation of 2,4-diarylpyridines. The efficacy of the developed conditions drives the reaction towards selective formation of 2,4-diarylpyridines over other pyridine derivatives. The described protocol showed good functional group tolerance with moderate to good yields of products.
- Gujjarappa, Raghuram,Vodnala, Nagaraju,Malakar, Chandi C.
-
supporting information
(2019/12/24)
-
- Palladium (II) complexes chelated by 1-substituted-4-pyridyl-1H-1,2,3-triazole ligands as catalyst precursors for selective ethylene dimerization
-
A series of neutral as well as cationic palladium methyl complexes bearing 1-substituted-4-pyridyl-1H-1,2,3-triazole ligands were prepared and fully characterized by a range of analytical techniques. Conventional and 2D NMR spectroscopy as well as single-crystal X-ray diffraction analysis unambiguously determined the molecular structure of the complexes. The neutral complexes activated by methylaluminoxane were found to be effective catalysts in the ethylene dimerization reaction. The catalyst performance of the in-situ-generated active species was compared with the discrete cationic complexes of the same ligand scaffold. Activities and selectivities for the two systems were remarkably similar, pointing to similarities in the nature of the active species. Both catalytic systems showed a strong correlation of activity and selectivity with the nature of the ligand scaffold. Highest activities were attained when electron-withdrawing groups were incorporated into the triazole ring, while increasing steric bulk in the ortho-position on the pyridyl ring of the ligand led to the almost exclusive dimerization of ethylene with selectivities up to 94% observed toward 1-butene.
- Joseph, Mohammed Cassiem,Swarts, Andrew John,Mapolie, Selwyn Frank
-
-
- Sustainable synthesis of quinolines (pyridines) catalyzed by a cheap metal Mn(I)-NN complex catalyst
-
This study represents the first example of a bidentate phosphine-free manganese(I)-NN complex catalyst for the synthesis of quinolines (pyridines) through acceptorless dehydrogenative condensation of various secondary alcohols with amino alcohols. The coupling reactions occurred at 3 mol% catalyst loading and 110°C, and tolerated diverse functional groups. Moderate to excellent yields ranging from 45% to 89% were achieved after 12 hr of reaction. The present protocol provides a concise and environmentally friendly method for the construction of heterocyclic compounds.
- Chai, Huining,Tan, Weiqiang,Lu, Yuanyuan,Zhang, Guangyao,Ma, Jiping
-
-
- Synthesis of Pyridines, Quinolines, and Pyrimidines via Acceptorless Dehydrogenative Coupling Catalyzed by a Simple Bidentate P^ N Ligand Supported Ru Complex
-
A ruthenium hydrido chloride complex (1) supported by a simple, heteroleptic bidentate P^N ligand (L1) containing a diarylphosphine and a benzannulated phenanthridine donor arm is reported. In the presence of base, complex 1 catalyzes multicomponent reactions using alcohol precursors to produce structurally diverse molecules including pyridines, quinolines, and pyrimidines via acceptorless dehydrogenative coupling pathways. Notably, L1 does not bear readily (de)protonated Br?nsted acidic or basic groups common to transition metal catalysts capable of these sorts of transformations, suggesting metal-ligand cooperativity does not play a significant role in the catalytic reactivity of 1. A rare example of an η2-aldehyde adduct of ruthenium was isolated and structurally characterized, and its role in acceptorless dehydrogenative coupling reactions is discussed.
- Mondal, Rajarshi,Herbert, David E.
-
supporting information
p. 1310 - 1317
(2020/04/15)
-
- Nickel(II)- and Palladium(II)-NHC Complexes from Hydroxypyridine Functionalized C,O Chelate Type Ligands: Synthesis, Structure, and Catalytic Activity toward Kumada-Tamao-Corriu Reaction
-
Hydroxypyridine functionalized imidazolium salts (2a-c) have been prepared in a one pot neat reaction between alkyl/aryl imidazoles and 2-chloro-3-hydroxypyridine. The imidazolium salts were used as proligands for the synthesis of new Ni(II) (3a, 3c, and 3c′) and Pd(II) NHC (4a-4c) complexes. Complexes, 3a, 3c, and 4a-4c are four coordinated with square planar geometry around the metal center and feature the C,O chelation of the heterobidentate NHC ligands, using carbene atoms and the O atom of the hydroxypyridine arm. Depending upon the steric bulk of the alkyl/aryl substituents on the ligand, either cis (3a and 4a) or trans (3c, 4b, and 4c) complexes are obtained. For the nickel complex with the 2c ligand, two different isomeric forms (3c and 3c′) were observed. In 3c, both the NHC ligands are bound via C2 and O atoms of the hydroxypyridine arm, whereas, in 3c′, one of the two ligands binds via C4 and N atoms of the hydroxypyridine side arm. 3c′ represents a unique square planar complex with the central metal atom bound simultaneously to both normal and abnormal carbenes. All the five complexes, except 3c′, were evaluated as catalysts for the Kumada-Tamao-Corriu cross-coupling reaction between phenylmagnesium bromide and different aryl chlorides at room temperature.
- Bhat, Irshad Ahmad,Avinash, Iruthayaraj,Anantharaman, Ganapathi
-
p. 1699 - 1708
(2019/03/07)
-
- Synthesis of heterobiaryls via Suzuki-Miyaura coupling reaction of potassium aryltrifluoroborates with heteroaryl halides in aqueous systems
-
A variety of heterobiaryl compounds have been synthesized by the Suzuki-Miyaura coupling reactions of heteroaryl halides with potassium aryltrifluoroborates. Pd (OAc)2 was found to be highly efficient for the Suzuki-Miyaura coupling reactions of various heteroaryl halides with potassium aryltrifluoroborates in aqueous systems, delivering the corresponding heterobiaryl compounds in good to excellent yields.
- Liu, Leifang,Zhao, Kai,Li, Wenbo,Liu, Mingli,Chen, Yuting,Dong, Yan
-
-
- Ferrocenyl palladacycles derived from unsymmetrical pincer-type ligands: Evidence of Pd(0) nanoparticle generation during the Suzuki-Miyaura reaction and applications in the direct arylation of thiazoles and isoxazoles
-
A new family of ferrocenyl-palladacycle complexes Pd(L1)Cl (Pd1) and Pd(L2)Cl (Pd2) were synthesized and characterized by UV-visible, IR, ESI-MS, and NMR spectral studies. The molecular structures of Pd1 and Pd2 were determined by X-ray crystallographic studies. Palladacycle catalyzed Suzuki-Miyaura cross-coupling reactions were investigated utilizing the derivatives of phenylboronic acids and substituted chlorobenzenes. Mechanistic investigation authenticated the generation of Pd(0) nanoparticles during the catalytic cycle and the nanoparticles were characterized by XPS, SEM and TEM analysis. Direct C-H arylation of thiazole and isoxazole derivatives employing these ferrocenyl-palladacycle complexes was examined. The reaction model for the arylation reaction implicating the in situ generation of Pd(0) nanoparticles was proposed.
- Maji, Ankur,Singh, Anshu,Mohanty, Aurobinda,Maji, Pradip K.,Ghosh, Kaushik
-
supporting information
p. 17083 - 17096
(2019/11/26)
-
- A new,: Substituted palladacycle for ppm level Pd-catalyzed Suzuki-Miyaura cross couplings in water
-
A newly engineered palladacycle that contains substituents on the biphenyl rings along with the ligand HandaPhos is especially well-matched to an aqueous micellar medium, enabling valued Suzuki-Miyaura couplings to be run not only in water under mild conditions, but at 300 ppm of Pd catalyst. This general methodology has been applied to several targets in the pharmaceutical area. Multiple recyclings of the aqueous reaction mixture involving both the same as well as different coupling partners is demonstrated. Low temperature microscopy (cryo-TEM) indicates the nature and size of the particles acting as nanoreactors. Importantly, given the low loadings of Pd invested per reaction, ICP-MS analyses of residual palladium in the products shows levels to be expected that are well within FDA allowable limits.
- Takale, Balaram S.,Thakore, Ruchita R.,Handa, Sachin,Gallou, Fabrice,Reilly, John,Lipshutz, Bruce H.
-
p. 8825 - 8831
(2019/10/16)
-
- Efficient construction of C–C bonds from aryl halides/aryl esters with arylboronic acids catalysed by palladium(II) thiourea complexes
-
A new set of palladium(II) complexes comprising phenyl(thiazolyl)thiourea ligands have been successfully synthesized and characterized with the aid of analytical as well as spectral (IR, UV–visible and NMR) methods. A distorted square-planar geometry with N^S coordination mode of thiourea ligands in the new palladium complexes was corroborated by single-crystal X-ray diffraction methods. Interestingly, the palladium(II) thiourea complexes showed the highest catalytic activity with 0.1 mol% catalyst loading in Suzuki–Miyaura cross-coupling reactions utilizing a range of aryl bromides/unactivated aryl chlorides with arylboronic acids as coupling partners in aqueous–organic media. Syntheses of diaryl ketones using aryl esters and arylboronic acids as coupling partners were also achieved with low catalyst loading within 20 h. The potential of our catalyst was demonstrated by its wide substrate scope, low catalyst loadings and high isolated yield. Moreover, the influences of key parameters like solvent, base, temperature and catalyst loading were also investigated.
- Thimma Sambamoorthy, Manikandan,Rengan, Ramesh,Jan Grzegorz, Malecki
-
-
- Synthesis and catalytic activity of ionic palladium N-heterocyclic carbene complexes
-
The synthesis of 3 benzimidazole-based ionic Pd(II)-NHC complexes (NHC: N -heterocyclic carbene) is presented. The structures of the complexes are as follows: [NHC-PdBr 3 ] ? [NHC] + . The ionic palladium(II)-NHC complexes were synthesized in high yields and were fully characterized by nuclear magnetic resonance spectroscopy, X-ray diffraction, LC-MS/MS, and elemental analysis. These complexes have been identified as active catalysts in Suzuki–Miyaura reactions in a solution of 2-propanol and water at room temperature for different aryl bromides.
- Ya?ar, Sedat,Akko?, Mitat,?zdemir, Nam?k,?zdemir, ?smail
-
p. 1622 - 1633
(2020/01/03)
-
- Synthesis of Asymmetrical 2,6-Diarylpyridines from Linear α,β,γ,δ-Unsaturated Ketones by Addition of Ammonium Formate Followed by Annulation
-
A simple and efficient method has been established for the synthesis of asymmetrical 2,6-diarylpyridines by cyclization of α,β,γ,δ-unsaturated ketones with ammonium formate under air atmosphere. The reaction is metal-free and operationally convenient from readily available starting materials. Thirty-three examples have been presented, most of which show good yields.
- Chen, Rener,Gao, Yejun,Ma, Yongmin
-
p. 3875 - 3882
(2019/10/11)
-
- 4-HO-TEMPO-Catalyzed Redox Annulation of Cyclopropanols with Oxime Acetates toward Pyridine Derivatives
-
A 4-HO-TEMPO-catalyzed redox strategy for the synthesis of pyridines through the annulation of cyclopropanols and oxime acetates has been developed. This protocol features good functional group tolerance and high chemoselectivity and also promises to be efficient for the late-stage functionalization of skeletons of drugs and natural products. Mechanism studies indicate that the reaction involves the in situ generated α,β-unsaturated ketones and imines as the key intermediates, which are derived from cyclopropanols and oxime acetates via a TEMPO/TEMPOH redox cycle, respectively. The pyridine products are formed as a result of annulation of enones with imines followed by TEMPO-catalyzed oxidative aromatization by excess oxime acetates. This method not only realizes the TEMPO-catalyzed redox reaction but also broadens the frontiers for TEMPO in catalysis.
- Zhan, Jun-Long,Wu, Meng-Wei,Wei, Dian,Wei, Bang-Yi,Jiang, Yu,Yu, Wei,Han, Bing
-
p. 4179 - 4188
(2019/05/01)
-
- Pd-Catalyzed Decarboxylation and Dual C(sp3)-H Functionalization Protocols for the Synthesis of 2,4-Diarylpyridines
-
The Pd-catalyzed decarboxylation and dual C(sp3)-H bond functionalization approaches have been described for the preparation of symmetrical and unsymmetrical 2,4-diarylpyridines. The developed transformations were realized using nonactivated aromatic ketones and amino acids as C-N sources. The efficacy of the catalyst and reagent combination drives the transformation toward the formation of desired products with high yields and selectivity. The described reaction conditions have seduced the self-reaction of phenylalanine via [2 + 2 + 2] cycloaddition and minimized the formation of 3,5-phenylpyridine as a side product, whereas using glycine as a C-N source, the corresponding 2,6-diarylpyridines were formed as minor products.
- Gujjarappa, Raghuram,Vodnala, Nagaraju,Kumar, Mohan,Malakar, Chandi C.
-
p. 5005 - 5020
(2019/04/25)
-
- Copper-Catalyzed Site-Selective Oxidative C?C Bond Cleavage of Simple Ketones for the Synthesis of Anilides and Paracetamol
-
A copper-catalyzed approach for the N-acylation of anilines with acetone and acetophenones via C?C bond cleavage is described. Under the developed conditions both CHCl3 and CH2Cl2 were identified as potential C1-source to promote the transformation. The reaction features a site selective C?C bond cleavage to install the amide moieties with high functional-group compatibility and wide substrate scope. The developed method avoids the use of sensitive and narcotic agents. The method also represents an excellent complement to the previous protocols with lower E-factor (13.91 mg/1 mg) than current industrially used method (E-factor 17.54 mg/1 mg). The developed approach has also been extended for the effective preparation of pyridine derivatives and paracetamol in gram scale. The course of the reaction was monitored by 1H NMR as a preliminary investigation of the reaction mechanism. (Figure presented.).
- Vodnala, Nagaraju,Gujjarappa, Raghuram,Hazra, Chinmoy K.,Kaldhi, Dhananjaya,Kabi, Arup. K.,Beifuss, Uwe,Malakar, Chandi C.
-
supporting information
p. 135 - 145
(2018/12/05)
-
- Phosphine Ligand-Free Ruthenium Complexes as Efficient Catalysts for the Synthesis of Quinolines and Pyridines by Acceptorless Dehydrogenative Coupling Reactions
-
A series of phosphine-free Ru(III)/Ru(II) complexes of NH functionalized N?N?N pincer ligands exhibit excellent activity for acceptorless dehydrogenative coupling (ADC) of secondary alcohols with 2-aminobenzyl or γ-amino alcohols to quinolines and pyridines. Ru(III) complexes [LRuCl3] (L=6-(3-R1,5-R2-1H-pyrazol-1-yl)-N-(pyridin-2-yl)pyridin-2-amine; 1 a: R1=R2=H (L1); 1 b: R1=R2=Me (L2); 1 c: R1=H, R2=CF3 (L3); 1 d: R1=H, R2=Ph (L4); 1bMe: L=6-(3,5-dimethyl-1H-pyrazol-1-yl)-N-methyl-N-(pyridin-2-yl)pyridin-2-amine (L2Me)) were obtained by refluxing RuCl3 ? xH2O with the corresponding ligand in EtOH. Five Ru(II) complexes [LRu(DMSO-κS)Cl2] (2 a: L=L1; 2 b: L=L2; 2 c: L=L3; 2 d: L=L4; 2bMe: L=L2Me) were formed by reducing the corresponding Ru(III) complex in refluxing EtOH. The latter complexes could also be prepared directly by refluxing Ru(DMSO)4Cl2 with the corresponding ligand in EtOH. These Ru(III) and Ru(II) complexes, especially 1 b/2 b, exhibited high catalytic efficiency and broad functional group tolerance in ADC reactions of secondary alcohols with 2-aminobenzyl or γ-amino alcohols to quinolines and pyridines. A detail mechanistic study indicated the Ru(III) complex was reduced into the Ru(II) species, which is the active catalytic center for ADC via a Ru?H/N?H bifunctional outer-sphere mechanism. This protocol provides a reliable, atom-economical and environmentally benign procedure for C?N and C?C bond formation.
- Guo, Bin,Yu, Tian-Qi,Li, Hong-Xi,Zhang, Shi-Qi,Braunstein, Pierre,Young, David J.,Li, Hai-Yan,Lang, Jian-Ping
-
p. 2500 - 2510
(2019/05/10)
-
- Synthesis, characterization, and catalytic activity of a new series of Ni(II), Cu(II), and Zn(II) complexes of N,N-O,O mixed-bidentate ligands for C–C cross-coupling reactions
-
A new series of air stable transition metal(II) complexes [M(II)(L)(Phen)], [M(II)(L)(Pip)] (M = Ni, Cu, and Zn) (H2L = 2,2′-methylenebis(4-nitrophenol)) (Phen =1,10-phenanthroline) (Pip = Piperazine) has been synthesized by incorporating the metal ion with bisphenol and 1,10-phenanthroline/piperazine ligands. The prepared metal complexes were characterized by FT-IR, UV–vis, 1H NMR, EPR, and mass spectrometry. The metal(II) complexes were potent catalysts for Suzuki–Miyaura and Kumada–Corriu coupling of various aryl halides under optimized conditions.
- Vinoth, Govindasamy,Indira, Sekar,Bharathi, Madheswaran,Nandhakumar, Arumugam,Sathishkumar, Kannappan,Shanmuga Bharathi, Kuppannan
-
p. 3934 - 3946
(2019/01/21)
-
- Sterically hindered N-aryl/benzyl substituted piperidoimidazolin-2-ylidene palladium complexes and their catalytic activities
-
A series of N-aryl (2a,b) or benzyl (2c,d) substituted piperidoimidazolinium salts and their palladium complexes (3a-d) were prepared and characterized by 1H, 13C NMR, IR spectroscopy and elemental analysis. The crystal structures of 3a and 3c have been determined by X-ray crystallography. Thermogravimetric analysis (TGA) was applied to complexes (3a–d). The palladium complexes have been employed as catalyst for Suzuki-Miyaura cross coupling. The N-aryl substituted complex 3b was a highly efficient precatalyst and successfully employed in Suzuki-Miyaura cross coupling reactions of (hetero)aryl chlorides with arylboronic acids in air. In addition, the oxidative addition step of the reaction mechanism involving chlorobenzene and the catalysts 3a, 3b, 3c and 3d were computationally investigated by the DFT-ω-B97X-D method and complete agreement were obtained with the catalytic results. To measure σ-donating and π-acceptor properties of the new ligands, the rhodium carbonyl complexes were also prepared.
- Gacal, Elif,Denizalt?, Serpil,K?nal, Arma?an,G?k?e, Ayta? Gürhan,Türkmen, Hayati
-
p. 6829 - 6838
(2018/10/20)
-
- Bis[ N, N ′-(2-indanolyl)]-1,5-diazacyclooctane as Unique Metal Ligand: Self-Assembly of Palladium Nanoparticles and Catalytic Reactivity on C-C Bond Formation
-
A previously unreported 1,5-diazacyclooctane-palladium(II) complex was synthesized using bis[ N, N ′-(2-indanolyl)]-1,5-diazacyclooctane, which was readily prepared via a novel [4+4] homocyclization of the unsaturated imine intermediate generated from acrolein and 1-amino-2-indanol. Interestingly, the 1,5-diazacyclooctane-palladium(II) complex self-assembled to form palladium nanoparticles. This approach readily provided palladium nanoparticles simply by heating a mixture of palladium(II) acetate and bis[ N, N ′-(2-indanolyl)]-1,4-diazacyclooctane in dichloroethane at mild temperatures. The 1,5-diazacyclooctane-derivative-palladium nanoparticles were successfully deployed in synthetic applications as a heterogeneous catalyst, facilitating Suzuki coupling and a challenging C-C bond formation via C(sp 3)-H activation under low catalyst loading conditions.
- Fujiki, Katsumasa,Tanaka, Katsunori
-
supporting information
p. 1097 - 1104
(2017/11/22)
-
- Stereoelectronic Flexibility of Ammonium-Functionalized Triazole-Derived Carbenes: Palladation and Catalytic Activities in Water
-
The postmodification approach allows convenient access to charge-tagged ammonium-functionalized bis(1,2,4-triazolin-5-ylidene)palladium(II) complexes even when the respective azolium salts are elusive. Bromo-functionalized 1,2,4-triazolium salts were first metalated to form the respective bromo-functionalized bis(NHC) complexes trans-[PdBr2(R-tazy-Br)2] (R = Ph, Cy, 1a,b). Subsequent postcoordinative nucleophilic substitutions converted the bromo into ammonium functions, leading to the water-soluble, charge-tagged complexes trans-[PdBr2(R-tazy-NEt3)2]Br2 (R = Ph, Cy, 2a,b). The catalytic activities of 2a,b in the aqueous Suzuki-Miyaura reaction were compared to those of their analogues 2c,d bearing more bulky mesityl and diisopropylphenyl substituents, and a detailed stereoelectronic profiling of the NHCs using %Vbur, HEP, and DFT calculations was conducted to rationalize their catalytic differences. Although all complexes are active, the more donating and less bulky complexes 2a,b performed significantly better than 2c,d at a very low catalyst loading of 0.001 mol %. 2a was found to be highly active for various aryl and heteroaryl bromides and some aryl chlorides. More importantly, this study discloses that NHCs with N-phenyl and N-cyclohexyl groups exhibit stereoelectronic flexibility, which could be the cause for the greater activities of their complexes.
- Nguyen, Van Ha,El Ali, Bassam M.,Huynh, Han Vinh
-
p. 2358 - 2367
(2018/07/31)
-
- NNN-Ruthenium Catalysts for the Synthesis of Pyridines, Quinolines, and Pyrroles by Acceptorless Dehydrogenative Condensation
-
The bidentate ruthenium complex (HO-C5H3N-CO-C5H3N-C5H4N)Ru(CO)2Cl2 (2) could transform to a tridentate product (HO-C5H3N-CO-C5H3N-C5H4N)Ru(CO)Cl2 (3), which further reacted with CH3ONa in the presence of PPh3 to convert to two complexes [(OC5H3N-CO-C5H3N-C5H4N)Ru(PPh3)2(CO)]Cl- (4) and [(OC5H3N-CO-C5H3N-C5H4N)Ru(PPh3)(CO)Cl] (5), via -OH deprotonation. The catalytic coupling cyclizations of secondary alcohols with amino alcohols were investigated, and complex 3 exhibited the highest activity. The coupling reactions proceeded in air with only 0.2 mol % catalyst loading and had a broad scope for the synthesis of pyridines, quinolones, and pyrroles.
- Deng, Danfeng,Hu, Bowen,Yang, Min,Chen, Dafa
-
p. 2386 - 2394
(2018/07/31)
-
- A highly efficient and recyclable Pd(II) metallogel catalyst: A new scaffold for Suzuki-Miyaura coupling
-
A convenient and practical procedure to prepare Pd(II) metallogel as a highly efficient and recyclable catalyst for Suzuki-Miyaura coupling has been developed. Such metallogel shows highly processable and reversible responses to thermal and mechanical stimuli. The xerogel is a highly efficient (0.005?mol% Pd) heterogeneous catalyst for Suzuki-Miyaura couplings with arylhalides and phenylboronic acids in excellent yield in water or ethanol under ambient atmosphere. The reaction could be scaled up to 10?gram scale with 0.001?mol% Pd catalyst loading with 99% yield. The catalyst can be recycled and reused at least seven times without loss of activity.
- Ye, Yu-Xin,Liu, Wan-Long,Ye, Bao-Hui
-
p. 100 - 105
(2016/11/11)
-
- Synthesis and catalytic applications of palladium N-heterocyclic carbene complexes as efficient pre-catalysts for Suzuki-Miyaura and Sonogashira coupling reactions
-
A new palladium complex series with N-heterocyclic carbene (NHC), pyridine and phosphine ligands, PdCl2(L)NHC (2a-c)(L = NHC), PdCl2(L1)NHC(3a-c)(L1 = pyridine), PdCl2(L2)NHC(4a-c)(L2 = triphenylphosphine) was synthesised and fully characterized. The catalytic activities of these complexes were screened for the Sonogashira and Suzuki-Miyaura reactions between arylhalides and phenylacetylene, and phenylboronic acid, respectively. The results pointed out that the carbene/phosphine complexes 4a-c exhibited excellent catalytic activities as compared to 2a-c, 3a-c, and the well-known systems for the palladium-catalysed Sonogashira reaction. The reactivity of 4a-c in these preliminary Sonogashira coupling tests seems to be higher than that of previously reported catalytic systems based on Pd(NHC) moieties. These new palladium NHC complexes are among the first reported palladium catalysts that are efficient for catalysing the Sonogashira reaction from arylchloride substrates.
- Boubakri,Yasar,Dorcet,Roisnel,Bruneau,Hamdi,Ozdemir
-
p. 5105 - 5113
(2017/07/11)
-
- Direct C-H Functionalization of Pyridine via a Transient Activator Strategy: Synthesis of 2,6-Diarylpyridines
-
A Pd-catalyzed highly selective direct diarylation of pyridines has been developed using a transient activator strategy. Both (MeO)2SO2 and Cu2O are required for this transformation. The in situ generated N-methylpyridinium salt can be arylated at both 2- and 6-positions under the cooperative Pd/Cu catalysis. A subsequent N-demethylation then gives the 2,6-diarylpyridines. This protocol provides a novel synthetic route for the symmetric 2,6-diarylpyridines.
- Zeng, Yang,Zhang, Chunchun,Yin, Changzhen,Sun, Maoshen,Fu, Haiyan,Zheng, Xueli,Yuan, Maolin,Li, Ruixiang,Chen, Hua
-
supporting information
p. 1970 - 1973
(2017/04/27)
-
- Method for double carbon-hydrogen activation and arylation of pyridine compounds
-
The invention discloses a method for double carbon-hydrogen activation and arylation of pyridine compounds, and belongs to the field of methodology of organic synthesis. The method comprises the following steps: mixing a palladium source, a phosphine ligand, a copper salt or an oxide of copper, an alkali and aryl halide, placing the mixture in a nitrogen gas environment, then adding an additive, 4-substituted pyridine and a solvent, and carrying out a heating reaction, to obtain a C2-site and C6-site double aryl substituted pyridine compounds through a carbon-hydrogen activation mechanism, wherein a substituent group of 4-substituted pyridine is any one of hydrogen, alkyl and aryl. The method has the advantages of wide application range, simple operation steps, no need of pre-activation of a pyridine ring, and no need of introduction of a guiding group, and extremely high atomic economy and practicability.
- -
-
Paragraph 0040; 0041; 0042; 0043; 0044
(2017/04/21)
-
- A Versatile Ru(II)-NNP Complex Catalyst for the Synthesis of Multisubstituted Pyrroles and Pyridines
-
A pincer-type Ru(II)-NNP complex bearing a pyrazolyl-(NH-PtBu2)-pyridine ligand was synthesized and structurally characterized by NMR, IR, elemental analysis, and X-ray single-crystal crystallographic determinations, which efficiently catalyzed the synthesis of multisubstituted pyrroles and pyridines by means of the reactions of secondary alcohols and β- or γ-amino alcohols through deoxygenation and selective C-N and C-C bond formation. The coupling reactions took place with 0.3 mol % catalyst loading and tolerated diverse functional groups. The present work provides an alternative method to construct highly active transition-metal complex catalysts from readily available ligands.
- Chai, Huining,Wang, Liandi,Liu, Tingting,Yu, Zhengkun
-
supporting information
p. 4936 - 4942
(2018/02/07)
-
- Efficient symmetrical bidentate dioxime ligand-accelerated homogeneous palladium-catalyzed Suzuki-Miyaura coupling reactions of aryl chlorides
-
A series of N,O-bidentate ligands were synthesized using the Vilsmeier-Haack reaction and oximation. 2,5-Dihydroxyterephthalaldehyde dioxime (L8) as an efficient N,O-symmetrical bidentate ligand was prepared from hydroquinone. It was studied as a high activity ligand for palladium-catalyzed Suzuki-Miyaura cross-coupling reactions of aryl chlorides with arylboronic acids under mild conditions. The coupling reactions were performed in the presence of PdCl2 as the catalyst, L8 as the ligand, Na2CO3 as the base, PEG-400 as the PTC and in ethanol/water (1?:?1) as an environmentally benign solvent at 85 °C. Plentiful biaryls were obtained by the optimized reaction with good yields at a low palladium loading of 0.20 mol%.
- Song, Jinyi,Zhao, Hongyan,Liu, Yang,Han, Huatao,Li, Zhuofei,Chu, Wenyi,Sun, Zhizhong
-
p. 372 - 376
(2016/12/30)
-
- Ligand-free Pd catalyzed cross-coupling reactions in an aqueous hydrotropic medium
-
A simple, efficient and ligand-free protocol for the Suzuki-Miyaura reaction and base-free Heck-Matsuda reactions under mild reaction conditions have been developed over palladium supported on activated carbon (Pd/C) in an aqueous hydrotropic solution. The catalyst Pd/C was fully characterized by TG-DTA, SEM, EDS, XRD, XPS, BET and ICP-AES analyses. This green methodology represents a cost-effective and operationally convenient method for the synthesis of a variety of biaryls, prochiral ketones, and acrylates under the conditions that are tolerant for a broad range of functional groups with good to excellent yields. The developed Pd/C-aqueous hydrotrope combined catalytic system is well suited for the 3R approach (reducible, robust, and recyclable) for different cross-coupling reactions without an appreciable loss of its activity.
- Jadhav, Sanjay N.,Kumbhar, Arjun S.,Rode, Chadrashekhar V.,Salunkhe, Rajashri S.
-
supporting information
p. 1898 - 1911
(2016/04/19)
-
- Mono- and multifold C-C coupling reactions catalyzed by a palladium complex encapsulated in MIL-Cr as a three dimensional nano reactor
-
The organic palladium complex (trans-dichlorobis(4-iodoaniline-κN)palladium(ii)) was encapsulated into a porous metal-organic framework MIL-Cr (Pd complex@MIL-Cr) using ship-in-a-bottle strategy. The novel catalyst as a three dimensional nanoreactor was fully characterized using different techniques such as XRD, BET, XPS, SEM, EDX, TEM and ICP. The Pd complex@MIL-Cr is isostructural to the parent MIL-Cr framework, with a high surface area and pore volume of ca. 1418 m2 g-1 and 0.87 cm3 g-1, respectively. The nanoreactor was highly efficient in the catalytic conversion of aryl halides, showing extraordinarily higher activity than the homogeneous Pd counterparts. Surprisingly, high yields were achieved in Suzuki-Miyaura and Heck coupling reactions of chloroarenes bearing a wide range of substituents. Besides, this protocol could be extended to the cross-couplings of 2-bromo and 2,6-dibromopyridine with arylboronic acids in excellent yields at room temperature. The Pd complex@MIL-Cr was also used as an efficient and convenient catalyst for the preparation of a series of C3-symmetric molecules with benzene, pyridine or pyrimidine units as the central core. Moreover, the catalyst could be recovered easily and reused several times without any considerable loss of its catalytic activity. Investigation of the nature of the recovered catalyst showed that the catalyst is converted to Pd nanoparticles.
- Rezaei, Saghar,Landarani-Isfahani, Amir,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
-
p. 92463 - 92472
(2016/10/11)
-
- Highly efficient palladium(II) hydrazone based catalysts for the Suzuki coupling reaction in aqueous medium
-
Synthesis of a new family of air stable palladium(ii)benzhydrazone complexes of the general formula [PdCl(PPh3)(L)] (where HL = thiophene aldehyde benzhydrazones) incorporating PPh3 and chloride as co-ligands has been described through a single and convenient step with good yields. All the new complexes have been fully characterized by means of elemental analysis, IR, UV-vis, and NMR spectral methods. The molecular structures of three of the complexes were determined by single crystal X-ray crystallography, which confirm the coordination mode of benzhydrazone and reveal the presence of a distorted square planar geometry around the Pd ion. The complexes 1-5 (0.05 mol%) have been found to be a highly active catalytic system in the mono and double Suzuki-Miyaura cross coupling reaction of deactivated aryl and heteroaryl bromides with different types of aryl boronic acids in neat water and the maximum yield was up to >99%. Notably, these catalysts work well with ultra-low loading of the catalysts and show high turnover numbers in a short time towards different substrates. Moreover, the catalysts could be simply recovered and reused five times without significant loss of efficiency.
- Muthumari, Subramanian,Ramesh, Rengan
-
p. 52101 - 52112
(2016/06/13)
-
- Evaluation of bis-cyclometalated alkynylgold(III) sensitizers for water photoreduction to hydrogen
-
Well-defined gold sensitizers for hydrogen production from water remain extremely rare despite decades of interest, and are currently limited to systems based on ruthenium, iridium or platinum complexes. This report details the synthesis and characterization of a series of neutral cyclometalated gold(iii) complexes of the type [(RC^N^CR)Au(CC-R′)] (R = H or tert-butyl group; R′ = aryl groups) that have been found to be good candidates to function as harvesting materials in light-induced electron transfer reactions. We established the efficacy of systems with these gold(iii) complexes as photosensitizers (PSs) in the production of renewable hydrogen in the presence of [Co(2,2′-bipyridine)3]Cl2 or [Rh(4,4′-di-tert-butyl-2,2′-bipyridine)3](PF6)3 as a H2-evolved catalyst and triethanolamine (TEOA) as a sacrificial electron donor in acetone-water solution. All complexes are active, and there is a more than threefold increase over other candidates in photocatalytic H2 generation activity. Under the optimal reaction conditions, hydrogen evolution took place through a photochemical route with the highest efficiency and with a turnover number (TON) of up to 1441.5 relative to the sensitizer over 24 hours. In the initial photochemical path, the reductive quenching of the excited gold(iii) complex by TEOA due to the latter's greater concentration in the system followed by electron transfer to the catalyst species is proposed to be the dominant mechanism. A photo-to-H2 quantum yield of approximately 13.7% was attained when illuminated with monochromatic light of 400 nm. Such gold(iii) complexes have demonstrated significant utility in solar-to-hydrogen reactions and thus represent a new effective class of light-harvesting materials. These results open possibilities for pursuing more efficient photosensitizers featuring gold(iii) complexes in photocatalytic solar energy conversion.
- Yu, Zhen-Tao,Liu, Xiao-Le,Yuan, Yong-Jun,Li, Yong-Hui,Chen, Guang-Hui,Zou, Zhi-Gang
-
supporting information
p. 17223 - 17232
(2016/11/13)
-
- Carboxyamido/carbene ligated palladium (II) complex: A versatile catalyst for the synthesis of aryl-substituted heteroarenes
-
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
-
supporting information
p. 150 - 153
(2016/12/06)
-
- A short synthesis of pyridines from deprotonated α-aminonitriles by an alkylation/RCM sequence
-
α-Aminonitriles can serve as versatile key precursors for the synthesis of nitrogen containing heterocycles. After unsuccessful trials involving the [1,2]-Stevens rearrangement of nitrile-stabilized ammonium ylides, we herein report a simple three-step synthesis of substituted pyridines based on an alkylation/ring-closing metathesis/aromatization sequence.
- Weber, Carina,Nebe, Marco M.,Kaluza, Lukas P. V.,Opatz, Till
-
p. 633 - 641
(2016/07/06)
-
- Metal-Free Assembly of Polysubstituted Pyridines from Oximes and Acroleins
-
Transition-metal-catalyzed synthesis of N-heterocycles from oximes has been previously well established. In this paper, for the first time a metal-free protocol with the combinational employment of iodine and triethylamine has been demonstrated to be effective to trigger the oxime-based synthesis of pyridines with high chemo-selectivity and wide functional group tolerance. A broad range of functional pyridines were prepared in moderate to excellent yields. While neither iodine nor triethylamine could trigger this transformation, mechanistic experiments indicated a radical pathway for the reaction. The resultant 2-aryl-substituted pyridines have been proved to be versatile building blocks in a range of transition-metal-catalyzed C-H functionalization reactions. (Chemical Equation Presented).
- Huang, Huawen,Cai, Jinhui,Tang, Lichang,Wang, Zilong,Li, Feifei,Deng, Guo-Jun
-
p. 1499 - 1505
(2016/03/01)
-
- Molecular Iodine-Mediated Chemoselective Synthesis of Multisubstituted Pyridines through Catabolism and Reconstruction Behavior of Natural Amino Acids
-
A new process has been developed for the selective construction of 2,6-disubstituted, 2,4,6-trisubstituted, and 3,5-disubstituted pyridines based on the catabolism and reconstruction behaviors of amino acids. Molecular iodine was used as a tandem catalyst to trigger the decarboxylation-deamination of amino acids and to promote the subsequent formation of the pyridine products.
- Xiang, Jia-Chen,Wang, Miao,Cheng, Yan,Wu, An-Xin
-
supporting information
p. 24 - 27
(2016/01/15)
-
- A Ruthenium Catalyst with Unprecedented Effectiveness for the Coupling Cyclization of - Amino Alcohols and Secondary Alcohols
-
The ruthenium complex (8-(2-diphenylphosphinoethyl)aminotrihydroquinolinyl)(carbonyl)(hydrido)ruthenium chloride exhibited extremely high efficiency toward the coupling cyclization of -amino alcohols with secondary alcohols. The corresponding products, pyridine or quinoline derivatives, are obtained in good to high isolated yields. On comparison with literature catalysts whose noble-metal loading with respect to -amino alcohols reached 0.5-1.0 mol % for Ru and a record lowest of 0.04 mol % for Ir, the current catalyst achieves the same efficiency with a loading of 0.025 mol % for Ru. The mechanism of acceptorless dehydrogenative condensation (ADC) was proposed on the basis of DFT calculations; in addition, the reactive intermediates were determined by GC-MS, NMR, and single-crystal X-ray diffraction. The catalytic process is potentially suitable for industrial applications.
- Pan, Bing,Liu, Bo,Yue, Erlin,Liu, Qingbin,Yang, Xinzheng,Wang, Zheng,Sun, Wen-Hua
-
p. 1247 - 1253
(2016/02/18)
-
- (Diphosphine)Nickel-catalyzed negishi cross-coupling: An experimental and theoretical study
-
The use of a strongly donating "(bis-dialkylphosphine)Ni" fragment promotes the catalytic coupling of a large range of ArCl and ArZnCl derivatives under mild conditions. Stoichiometric mechanistic investigations and DFT calculations prove that a Ni0/NiII cycle is operative in this system.
- Nicolas, Emmanuel,Ohleier, Alexia,D'Accriscio, Florian,Pécharman, Anne-Frédérique,Demange, Matthieu,Ribagnac, Philippe,Ballester, Jorge,Gosmini, Corinne,Mézailles, Nicolas
-
supporting information
p. 7690 - 7694
(2015/05/20)
-
