- Efficient conversion of acetophenones into 1,3,5-triarylbenzenes catalyzed by bismuth(III) trifluoromethanesulfonate tetrahydrate
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Bismuth(III) trifluoromethanesulfonate tetrahydrate is found to efficiently catalyze the cyclotrimerization of acetophenones into 1,3,5-triarylbenzenes in good yields. Georg Thieme Verlag Stuttgart.
- Ono, Fumiaki,Ishikura, Yuichi,Tada, Yuusuke,Endo, Masato,Sato, Tsuneo
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- Highly efficient and novel method for synthesis of 1,3,5-triarylbenzenes from acetophenones
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Heteropolyacid-phosphomolybdic acid has been found to be an efficient and recyclable catalyst for cyclotrimerization of acetophenones into 1,3,5-triarylbenzenes in good yields.
- Phatangare, Kiran,Padalkar, Vikas,Mhatre, Devidas,Patil, Ketan,Chaskar, Atul
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- Thionyl chloride-catalyzed preparation of microporous organic polymers through aldol condensation
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We demonstrated the synthesis of five kinds of microporous organic polymers based on aldol self-condensation of di- and multiacetyl-containing building blocks catalyzed by thionyl chloride. The α,β-unsaturated ketone (dimerization) and 1,3,5-trisubstitute
- Zhao, Yan-Chao,Zhou, Ding,Chen, Qi,Zhang, Xin-Jian,Bian, Ning,Qi, Ai-Di,Han, Bao-Hang
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- Efficient one-step synthesis of C 3-symmetrical benzenoid compounds mediated by SOCl 2/EtOH
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An efficient one-step synthesis of branched functionalized benzenoid compounds from aryl methyl ketones mediated by SOCl2/EtOH is described; some novel C 3-symmetrical molecules were prepared with satisfactory yields. The method enjo
- Zhao, Sanhu,Kang, Lina,Ge, Haixia,Yang, Feifei,Wang, Chenlu,Li, Chang,Wang, Qiang,Zhao, Minggen
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- Independent electrocyclization and oxidative chain cleavage along the backbone of cis-poly(phenylacetylene)
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cis-Poly(phenylacetylene) (PPA) and cis-poly(pentadeuteriophenylacetylene) (PPA-d5) undergo similar thermally induced transformations in bulk and solution. The structures identified in thermally treated samples include cis - trans isomerization of the backbone, cyclohexadiene repeat units in the main chain, and extruded 1,3,5-triphenylbenzene (1,3,5-C6H 3Ph3). Among these structures, cyclohexadiene sequences along the backbone formed by intramolecular cyclization are the principal products in all solvents regardless of temperature and the presence or absence of ambient light or O2. We propose that cyclohexadiene structures form via 6π electrocyclization of triene sequences and, therefore, are an unavoidable consequence of cis-alkene units of the polyene backbone. Concurrent with cyclization, decrease of molecular weight and increase of molecular weight distribution are observed. Traces of acid lead to a dramatic increase in cyclization. Extrusion of 1,3,5-C6H3Ph3 results from cyclohexadiene repeat units and is slower than electrocyclization, even in the presence of acid, light, or O2. In the presence of ambient light, O2 accelerates the rate of cyclization and extrusion of 1,3,5-C6H3Ph3, the decrease of molecular weight, and the formation of carbonyl-containing products detected in a 5:1 molar ratio to extruded 1,3,5-C6H3Ph3. Under these conditions, the most dramatic changes in molecular weight and molecular weight distribution are observed.
- Percec, Virgil,Rudick, Jonathan G.
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- TiCl3(OTf) catalyses the efficient conversion of acetophenones to 1,3,5-triaryl benzenes
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The quantitative conversion of different substituted acetophenones to their corresponding 1,3,5-triaryl benzenes was achieved in the presence of catalytic amounts of TiCl3(OTf) in sealed tubes at 90-100°C.
- Iranpoor,Zeynizaded
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- Simple and convenient synthesis of 1,3,5-triarylbenzenes from ketones
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A new and efficient synthesis of a series of 1,3,5-triarylbenzenes was accomplished in good yields via the triple condensation of aryl methyl ketones promoted by thionyl chloride in anhydrous ethanol. The method is simple and convenient.
- Hu, Anan,Zhang, Anjiang,Ding, Lisheng,Lei, Xinxiang,Zhang, Lixue
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- Silver(I) Interactions with Ketones. Site of Complexation with Acetophenones and Effectiveness as a Lewis Acid Catalyst
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Aromatic ketones present three possible sites for complexation of Ag(1+): the oxygen lone pair, the ? electrons of the carbonyl bond, and the ? electrons of the aromatic ring.Upfield shifts of (13)C chemical shifts of meta and para carbons of acetophenone in the presence of silver nitrate showed that Ag(1+) complexes with the aromatic ring moiety in water.This contrasts with previous results in methylene chloride in which the carbonyl group is not hydrogen bonded to solvent and acts as an n donor toward Ag(1+).In the solid state, an X-ray structure determination of (p-methylacetophenone)2AgBF4 showed that Ag(1+) was tetracoordinated to two carbonyl oxygens (2.36 Angstroem) and to two aromatic rings of different ketone molecules (2.55- and 2.72-Angstroem distances to meta and ortho carbons, respectively).Thus in the solid state, acetophenone acts both as an n and ? donor.The Ag-O bond was shorter than most Ag-O bonds and appears to contribute more to the stabilization of the complex than Ag(1+) interactions with the benzene rings.An sp2 hybridization at oxygen was indicated by an AgOC angle of 137 deg and the fact that Ag(1+) is only 6.2 deg above the plane of the carbonyl bond.Although Ag(1+) catalyzed an aldol condensation of acetophenone in 1,2-dichloroethane at 70-80 deg C, rates of hydrogen exchange for acetone in deuterated water at 44 deg C showed no catalytic activity of AgNO3 or LiNO3.
- Crist, DeLanson R.,Hsieh, Zon-Hong,Quicksall, Carl O.,Sun, Michael K.
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- OLIGOMERISATION OF PHENYL ACETYLENE OVER TITANIUM OXIDE SUPPORTED ON SILICA - ALUMINA CATALYST
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Titanium oxide on silica-alumina support is found to be effective for oligomerisation of phenyl acetylene.Cyclic trimerisation of the acetylene leading to trisubstituted benzene was also found to occur during the oligomerisation, in addition of the formation of small quantities of a ketone by the reaction of phenyl acetylene with moisture over the catalyst surface.
- Kumar, V. G.,Shoba, T. S.,Rao, K. V. C.
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- 2-cyano-iso-propyl radical addition to alkynes
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The thermolysis of azobisisobutyronitrile (AIBN) in benzene in the presence of various mono- and di-substituted acetylenes has been investigated in order to ascertain the chemical reactivity of transient 2-cyano-isopropyl radical (CPR) towards carbon-carbon triple bonds. Results show that this rather sluggish and bulky carbon centered radical successfully adds in a regioselective fashion to alkynes bearing an electron acceptor phenyl, methoxycarbonyl and trimethylsilyl substituent, but fails with alkylacetylenes and those sterically hindered. The produced vinyl radicals undergo H-abstraction reaction, alkyne addition, aromatic addition and intramolecular cyclization in a relative proportion strongly dependent upon the nature of both 1- and 2-substituent. Two unprecedented examples of 4-exo and 6-exo vinyl radical cyclization onto the cyano triple bond are reported.
- Montevecchi, Pier Carlo,Navacchia, Maria Luisa,Spagnolo, Piero
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- Fabrication of palladium nanoparticles as effective catalysts by using supramolecular gels
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Two-component supramolecular gels were made through self-assembly of tetrazolyl derivatives and Pd(OAc)2. The robust gels indicated high storage modulus (>10,000 Pa) and loss modulus, which were studied by rheological measurements. The formed P
- Zhang, Wei,Xie, Zhi-Gang
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- Chiral diphosphine derivatives of alkylidyne tricobalt carbonyl clusters - A comparative study of different cobalt carbonyl (pre)catalysts for (asymmetric) intermolecular Pauson-Khand reactions
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Reaction of the tricobalt carbyne cluster [Co3(μ3-CH)(CO)9] with chiral diphosphines of the Josiphos and Walphos families affords the new clusters [Co3(μ3-CH)(CO)7(P-Pμ)] in good yield (P-Pμ = J004 (1), J005 (2), J007 (3), W001 (4), W003 (5)). The new alkylidyne tricobalt clusters, and the previously known [Co3(μ3-CH)(CO)7(μ-J003)], have been tested as catalysts/catalyst precursors for intermolecular Pauson-Khand cyclization, using norbornene and phenylacetylene as substrate. The diphosphine-substituted tricobalt carbonyl clusters proved to be viable catalysts/catalyst precursors that gave products in moderate to good yields, but the enantiomeric excesses were low. When the chiral diphosphine ligands were used as promoters/auxiliary ligands for the same Pauson-Khand reaction, using either [Co2(CO)8] or [Co4(CO)12] as catalyst precursors, both the overall yields and the selectivities with respect to cyclopentenone formation were significantly improved. The best results were obtained for ligands J007 and W001, with [Co4(CO)12] as pre-catalyst, where yields of 96%, and virtually 100% selectivity were obtained. However, the enantioselectivity of product formation was low or non-existent. The crystal structure of [Co3(μ3-CH)(CO)7(μ-J004)] is described. [J003 = [(R)-1-{(S)-2-(dicyclohexylphosphino)-ferrocenyl} ethyldicyclohexylphosphine], J004 = [(R)-1-{(S)-2-(dicyclohexylphosphino)-ferrocenyl} ethyldiphenylphosphine], J005 = [(R)-1-{(S)-2-(diphenylphosphino)ferrocenyl}ethyl-di-3,5-xylylphosphine], J007 = [(R)-1-{(S)-2-di-(4-methoxy-3,5-dimethylphenyl)phosphino)ferrocenyl} ethyldicyclohexylphosphine], W001 = [(R)-1-{(R)-2-(2′-diphenyl phosphinophenyl)ferrocenyl} ethyldi(bis-3,5-trifluoromethylphenyl)phosphine], W003 [(R)-1-{(R)-2-(2′-diphenylphosphino-phenyl)ferrocenyl}ethyldi(3,5-xylyl)phosphine].
- Mottalib, M. Abdul,Haukka, Matti,Nordlander, Ebbe
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- SRN1 and stille reactions: A new synthetic strategy
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The photostimulated reaction of Me3Sn- ion with mono, di and trichloro arenes in liquid ammonia gave very good yields of stannanes by the SRN1 mechanism. These products reacted by a palladium-catalized cross coupling reaction with halobenzenes to give phenylated products also in very goods yields. Similar yields can be obtained in one-pot reactions.
- Corsico, Eduardo F.,Rossi, Roberto A.
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- Catalytic three-component coupling of alkynes, imines, and organoboron reagents
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An unusual degree of functional group compatibility for imine addition reactions was observed in the assembly of allylic amines from alkynes, imines, and organoboron reagents (boronic acids or boranes) by using a catalyst derived from [Ni(cod)2] and (c-C5H9)3P - this catalytic three-component process (see scheme) is tolerant of ketones, esters, and hydroxylic solvents.
- Patel, Sejal J.,Jamison, Timothy F.
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- A facile synthesis of 1,3,5-triaryl benzenes from acetophenone diethyl ketals in the presence of acetyl chloride and SmCl3
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Samarium trichloride, SmCl3, has been found to be an efficient catalyst for the synthesis of 1,3,5-triaryl benzenes from acetophenone diethyl ketals in the presence of acetyl chloride under solvent of pentane and mild conditions.
- Cheng, Ke-Jun,Ding, Zong-Biao,Wu, Shi-Hui
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- Effect of phosphonium ionic liquid/Pd ratio on the catalytic activity of palladium nanoparticles in Suzuki cross-coupling reaction
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Phosphonium salts were synthesized and used as support for palladium nanoparticles. It was demonstrated that the catalytic behavior of palladium nanoparticles in Suzuki cross-coupling reaction is determined by the ratio of the phosphonium ionic liquid to
- Arkhipova, D.,Ermolaev, V.,Gaynanova, G.,Hey-Hawkins, E.,Miluykov, V.,Oeckler, O.,Wagner, G.,Zakharova, L.
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- Suzuki cross-coupling of hexachlorobenzene promoted by the Buchwald ligands
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The study of cross-coupling between hexachlorobenzene and phenylboronic acid comprised five Buchwald ligands, from which 2-dicyclohexylphosphino-2′-(dimethylamino)biphenyl (DavePHOS) provided the best conversion. When excess of phenylboronic acid was used, a mixture of isomeric tri-, tetra- and pentaphenyl-substituted derivatives in the ~10:70:20 ratio was obtained, along with minor amounts of hydrodechlorination products.
- Burukin, A. S.,Vasil’ev, A. A.,Zhdankina, G. M.,Zlotin, S. G.
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p. 169 - 172
(2022/02/17)
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- Hydrogen-Bonding Controlled Nickel-Catalyzed Regioselective Cyclotrimerization of Terminal Alkynes
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Herein we report a hydrogen-bonding controlled nickel-catalyzed regioselective cyclotrimerization of terminal alkynes in moderate to excellent yields with high regioselectivities toward 1,3,5-trisubstituted benzenes. This method features a cheap catalyst, mild reaction conditions, and excellent functional group compatibility. The Ni-B(OH)2 complex in situ generated from NiCl2·DME and tetrahydroxydiboron might act as an active catalyst. After three consecutive cis-additions of terminal alkynes, internal migratory insertion cyclization, and β-boron elimination induced aromatization, 1,3,5-trisubstituted benzenes were selectively established.
- Yang, Kai,Wang, Pengfei,Sun, Ze-Ying,Guo, Minjie,Zhao, Wentao,Tang, Xiangyang,Wang, Guangwei
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supporting information
p. 3933 - 3938
(2021/05/26)
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- Iron-catalyzed trimerization of terminal alkynes enabled by pyrimidinediimine ligands: A regioselective method for the synthesis of 1,3,5-substituted arenes
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The development of pyrimidine-based analogues of the well-known pyridinediimine (PDI) iron complexes enables access to a functional-group-tolerant methodology for the catalytic trimerization of terminal aliphatic alkynes. Remarkably, in contrast to established alkyne trimerization protocols, the 1,3,5-substituted arenes are the main reaction products. Preliminary mechanistic investigations suggest that the enhanced π-acidity of the pyrimidine ring, combined with the hemilability of the imine groups coordinated to the iron center, facilitates this transformation. The entry point in the catalytic cycle is an isolable iron dinitrogen complex. The catalytic reaction proceeds via a 1,3-substituted metallacycle, which explains the observed 1,3,5-regioselectivity. Such a metallacycle could be isolated and represents a rare 1,3-substituted ferracycle obtained through alkyne cycloaddition.
- Doll, Julianna S.,Eichelmann, Robert,Hertwig, Leif E.,Bender, Thilo,Kohler, Vincenz J.,Bill, Eckhard,Wadepohl, Hubert,Ro?ca, Drago?-Adrian
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p. 5593 - 5600
(2021/05/31)
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- Variation on the π-Acceptor Ligand within a RhI?N-Heterocyclic Carbene Framework: Divergent Catalytic Outcomes for Phenylacetylene-Methanol Transformations
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A series of neutral and cationic rhodium complexes bearing IPr {IPr=1,3-bis-(2,6-diisopropylphenyl)imidazolin-2-carbene} and π-acceptor ligands are reported. Cationic species [Rh(η4-cod)(IPr)(NCCH3)]+ and [Rh(CO)(IPr)(L)2]+ (L=pyridine, CH3CN) were obtained by chlorido abstraction in suitable complexes, whereas the cod-CO derivative [Rh(η4-cod)(IPr)(CO)]+ was formed by the carbonylation of [Rh(η4-cod)(IPr)(NCCH3)]+. Alternatively, neutral derivatives of type RhCl(IPr)(L)2 {L=tBuNC or P(OMe)3} can be accessed from [Rh(μ-Cl)(η2-coe)(IPr)]2. In addition, the mononuclear species Rh(CN)(η4-cod)(IPr) was prepared by cyanide-chlorido anion exchange, which after carbonylation afforded the unusual trinuclear compound [Rh{1κC,2κN-(CN)}(CO)(IPr)]3. Divergent catalytic outcomes in the phenylacetylene-methanol transformations have been observed. Thus, enol ethers, arisen from hydroalkoxylation of the alkyne, were obtained with neutral Rh?CO catalyst precursors whereas dienol ethers were formed with cationic catalysts. Variable amounts of alkyne dimerization, cyclotrimerization or polymerization products were obtained in the absence of a strong π-acceptor ligand on the catalyst.
- Galiana-Cameo, María,Passarelli, Vincenzo,Pérez-Torrente, Jesús J.,Di Giuseppe, Andrea,Castarlenas, Ricardo
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p. 2947 - 2957
(2021/07/16)
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- Synthesis method of 1,3,5-trisubstituted aryl compound
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The invention belongs to the field of organic synthesis, and particularly relates to a synthesis method of a 1,3,5-trisubstituted aryl compound. The method is carried out according to a process route as described in a formula (III). In the formula (III), R, R and R are any substituent group, X is C-R, and R is H or any other substituent group. The invention provides the novel method for synthesizing the 1,3,5-trisubstituted aryl compound. The large-scale production and application of the 1,3,5-trisubstituted aryl compound are greatly promoted.
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Paragraph 0062-0066
(2021/08/06)
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- Case Study of N-iPr versus N-Mes Substituted NHC Ligands in Nickel Chemistry: The Coordination and Cyclotrimerization of Alkynes at [Ni(NHC)2]
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A case study on the effect of the employment of two different NHC ligands in complexes [Ni(NHC)2] (NHC=iPr2ImMe 1Me, Mes2Im 2) and their behavior towards alkynes is reported. The reaction of a mixture of [Ni2(iPr2ImMe)4(μ-(η2 : η2)-COD)] B/ [Ni(iPr2ImMe)2(η4-COD)] B’ or [Ni(Mes2Im)2] 2, respectively, with alkynes afforded complexes [Ni(NHC)2(η2-alkyne)] (NHC=iPr2ImMe: alkyne=MeC≡CMe 3, H7C3C≡CC3H7 4, PhC≡CPh 5, MeOOCC≡CCOOMe 6, Me3SiC≡CSiMe3 7, PhC≡CMe 8, HC≡CC3H7 9, HC≡CPh 10, HC≡C(p-Tol) 11, HC≡C(4-tBu-C6H4) 12, HC≡CCOOMe 13; NHC=Mes2Im: alkyne=MeC≡CMe 14, MeOOCC≡CCOOMe 15, PhC≡CMe 16, HC≡C(4-tBu-C6H4) 17, HC≡CCOOMe 18). Unusual rearrangement products 11 a and 12 a were identified for the complexes of the terminal alkynes HC≡C(p-Tol) and HC≡C(4-tBu-C6H4), 11 and 12, which were formed by addition of a C?H bond of one of the NHC N-iPr methyl groups to the C≡C triple bond of the coordinated alkyne. Complex 2 catalyzes the cyclotrimerization of 2-butyne, 4-octyne, diphenylacetylene, dimethyl acetylendicarboxylate, 1-pentyne, phenylacetylene and methyl propiolate at ambient conditions, whereas 1Me is not a good catalyst. The reaction of 2 with 2-butyne was monitored in some detail, which led to a mechanistic proposal for the cyclotrimerization at [Ni(NHC)2]. DFT calculations reveal that the differences between 1Me and 2 for alkyne cyclotrimerization lie in the energy profile of the initiation steps, which is very shallow for 2, and each step is associated with only a moderate energy change. The higher stability of 3 compared to 14 is attributed to a better electron transfer from the NHC to the metal to the alkyne ligand for the N-alkyl substituted NHC, to enhanced Ni-alkyne backbonding due to a smaller CNHC?Ni?CNHC bite angle, and to less steric repulsion of the smaller NHC iPr2ImMe.
- Tendera, Lukas,Helm, Moritz,Krahfuss, Mirjam J.,Kuntze-Fechner, Maximilian W.,Radius, Udo
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supporting information
p. 17849 - 17861
(2021/11/17)
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- Solvent-dependent metal-free chemoselective synthesis of benzimidazoles and 1,3,5-triarylbenzenes from 2-amino anilines and aryl alkyl ketones catalyzed by I2
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A solvent-dependent I2-catalyzed chemoselective reaction was developed for the synthesis of benzimidazoles and 1,3,5-triarylbenzenes via the annulation of 2-amino anilines and aryl alkyl ketones or the cyclization of aryl alkyl ketones, respectively. With 1,4-dioxane as the solvent, sequential C[sbnd]N bond formation followed by C(CO)-C(CH3) bond cleavage leads to the formation of benzimidazoles in a highly selective manner while aldol-type self-condensation of aryl alkyl ketones predominates using PhNO2 or PhCl as the solvent to afford 1,3,5-triarylbenzenes.
- Ding, Yuxin,Ma, Renchao,Ma, Yongmin
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supporting information
(2021/04/09)
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- Buchwald ligand-assisted Suzuki cross-coupling of polychlorobenzenes
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Screening of four Buchwald ligands for the cross-coupling of isomeric di-, tri- and tetrachlorobenzenes with arylboronic acids revealed that good yields of exhaustive substitution can be best provided by 2-dicyclohexylphosphino-2′-(dimethylamino) biphenyl (DavePHOS).
- Burukin, Alexander S.,Vasil'ev, Andrei A.,Zhdankina, Galina M.,Zlotin, Sergei G.
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p. 400 - 402
(2021/06/07)
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- Molecular engineered palladium single atom catalysts with an M-C1N3subunit for Suzuki coupling
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Single atom catalysis has emerged as a powerful technique for catalysis due to its outstanding performance and atom economy. Controlling the hybridization of the atom with its environment is crucial in determining the selectivity and/or yield of the reaction. However, the single atom environment is usually ill-defined and hard to predict because the pyrolysis process used in preparing SACs damages the original status of the precursors in the catalyst preparation. A molecular engineering approach to synthesize single atom catalysts (SACs) on a heterogeneous template provides a strategy to make SACs with a highly uniform coordinating environment. Herein, we report the preparation of a molecular engineered Pd single atom catalyst with a pre-defined M-N3C1 coordination (Pd-N3C1-SAC) using a structure-rigid Pd-N3C1 porphyrin as the precursor, which shows more efficient Suzuki coupling compared with the SAC with Pd-N4 coordination. The origin of the high activity of the Pd-N3C1-SAC is revealed through density functional theory calculations, where a lower reaction barrier for the rate-determining oxidative addition is identified. This journal is
- Liu, Jia,Chen, Zhongxin,Liu, Cuibo,Zhang, Bao,Du, Yonghua,Liu, Chen-Fei,Ma, Lu,Xi, Shibo,Li, Runlai,Zhao, Xiaoxu,Song, Jingting,Sui, Xin Zhi,Yu, Wei,Miao, Ling,Jiang, Jianjun,Koh, Ming Joo,Loh, Kian Ping
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supporting information
p. 11427 - 11432
(2021/05/19)
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- Amine-Tagged Fragmented Ligand Installation for Covalent Modification of MOF-74
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MOF-74 is one of the most explored metal–organic frameworks (MOFs), but its functionalization is limited to the dative post-synthetic modification (PSM) of the monodentate solvent site. Owing to the nature of the organic ligand and framework structure of MOF-74, the covalent PSM of MOF-74 is very demanding. Herein, we report, for the first time, the covalent PSM of amine-tagged defective Ni-MOF-74, which is prepared by de novo solvothermal synthesis by using aminosalicylic acid as a functionalized fragmented organic ligand. The covalent PSM of the amino group generates metal binding sites, and subsequent post-synthetic metalation with PdII ions affords the PdII-incorporated Ni-MOF-74 catalyst. This catalyst exhibits highly efficient, size-selective, and recyclable catalytic activity for the Suzuki–Miyaura cross-coupling reaction. This strategy is also useful for the covalent modification of amine-tagged defective Ni2(DOBPDC), an expanded analogue of MOF-74.
- Lim, Jaewoong,Lee, Seonghwan,Ha, Hyeonbin,Seong, Junmo,Jeong, Seok,Kim, Min,Baek, Seung Bin,Lah, Myoung Soo
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supporting information
p. 9296 - 9300
(2021/03/09)
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- Suzuki-Miyaura Cross-Coupling of Sulfoxides
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The utilization of diphenyl sulfoxides as versatile electrophilic coupling partners for the Suzuki-Miyaura reaction via C-S bond cleavage was successfully developed under palladium-N-heterocyclic carbene catalysis. The reactions showed good functional group compatibility, proceeded well under mild conditions, and provided biaryls in yields of up to 96%. A wide range of useful functional groups, such as fluoro, chloro, ether, hydroxyl, amide, cyano, keto, trimethylsilyl (TMS), and ester were tolerated under the reaction conditions; however, the use of phenylboronic anhydride and arylboronic acid pinacol esters generally would lead low yields. Good regioselectivity for the electron-poor phenyl group was achieved when unsymmetrical diphenyl sulfoxides were used. The protocol is applicable at the gram scale even with half the amount of catalyst. Density functional theory calculations were performed to investigate the reaction mechanism, indicating that the reaction occurred through oxidative addition, transmetalation, and reductive elimination to provide the final coupling product.
- Abduhulam, Hayrul,Cao, Changsheng,Chen, Qianwei,Dang, Yanfeng,Li, Chengxi,Shi, Yanhui,Wu, Shufeng,Yan, Shuqin
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p. 8168 - 8176
(2020/09/18)
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- A simple Lewis acid induced reaction of phenols with electrophiles: Synthesis of functionalized 4H-chromenes and ortho-benzylphenols
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Lewis acid ZnCl2 promoted cyclization protocol to 4H-chromenes is accomplished, using readily available phenols and acetophenones as starting materials. Interestingly, the process is feasible under the solvent free environment. Synthesis of a variety of 4H-chromenes have been accomplished using this strategy. In addition, this concept is extended to the synthesis of ortho-benzylphenols by treating phenols either with styrenes or secondary benzylic alcohols.
- Sreenivasulu, Chinnabattigalla,Thadathil, Ditto Abraham,Pal, Sumit,Gedu, Satyanarayana
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p. 112 - 122
(2019/11/19)
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- Metal-free and solvent-free synthesis of: M -terphenyls through tandem cyclocondensation of aryl methyl ketones with triethyl orthoformate
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Reported here is a novel cyclocondensation of aryl methyl ketones and triethyl orthoformate for the simple synthesis of m-terphenyls. In the presence of a catalytic amount of TfOH, alkyl- and chloro-substituted acetophenones produced a series of terphenyls through a tandem reaction which merged six steps into a one-pot procedure. Moreover, the corresponding ester products were obtained when using other substituted acetophenones as the starting materials under the same reaction conditions.
- Gan, Zongjie,Jiang, Wengao,Luo, Juan,Tang, Qiang,Xiao, Xiaoqin
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p. 12113 - 12118
(2020/04/10)
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- Boron–Nitrogen-Doped Nanographenes: A Synthetic Tale from Borazine Precursors
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In this work, a comprehensive account of the authors’ synthetic efforts to prepare borazino-doped hexabenzocoronenes by using the Friedel–Crafts-type electrophilic aromatic substitution is reported. Hexafluoro-functionalized aryl borazines, bearing an ortho fluoride leaving group on each of the N- and B-aryl rings, was shown to lead to cascade-type electrophilic aromatic substitution events in the stepwise C?C bond formation, giving higher yields of borazinocoronenes than those obtained with borazine precursors bearing fluoride leaving groups at the ortho positions of the B-aryl substituents. By using this pathway, an unprecedented boroxadizine-doped PAH featuring a gulf-type periphery could be isolated, and its structure proven by single-crystal X-ray diffraction analysis. Mechanistic studies on the stepwise Friedel–Crafts-type cyclization suggest that the mechanism of the planarization reaction proceeds through extension of the π system. To appraise the doping effect of the boroxadizine unit on the optoelectronic properties of topology-equivalent molecular graphenes, the all-carbon and pyrylium PAH analogues, all featuring a gulf-type periphery, were also prepared. As already shown for the borazino-doped hexabenzocoronene, the replacement of the central benzene ring by its B3N2O congener widens the HOMO–LUMO gap and dramatically enhances the fluorescence quantum yield.
- Dosso, Jacopo,Battisti, Tommaso,Ward, Benjamin D.,Demitri, Nicola,Hughes, Colan E.,Williams, P. Andrew,Harris, Kenneth D. M.,Bonifazi, Davide
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supporting information
p. 6608 - 6621
(2020/04/22)
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- Evaluation of the Transferability of the “Flexible Steric Bulk” Concept from N-Heterocyclic Carbenes to Planar-Chiral Phosphinoferrocenes and their Electronic Modification
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The concept of “flexible steric bulk” is discussed at 2-phenylvinyl-1-phosphinoferrocenes. The introduction of freely rotatable 1'-silyl groups increases the catalytic productivity within the synthesis of tri-ortho-substituted biaryls by Suzuki–Miyaura C,C cross-coupling reactions, giving higher yields with 1/4 of catalyst concentration than for the non-silylated derivatives. Electronic modification of the P and the vinyl donor functionalities was investigated by introducing substituents in the para positions of both groups. Therein, electron-withdrawing phosphines increased the yield from 78 to 91 percent for a given biaryl, by changing from a diphenylphosphino to the P(p-CN-C6H4)2 unit. Opposite results, obtained from electron-donating and sterically demanding phosphines, were in accordance with the 1J(31P,77Se) values. However, the electron density of the ferrocenyl backbone, expressed by the redox potential of the first ferrocenyl-related redox process, cannot be correlated with the donor-properties at the P atom. Changing from a PPh2-substituted ferrocene to a (RA)-1,1'-binaphthyl-containing phosphonite, a complex interaction between the axial- and the planar-chiral motifs occurs, resulting a change of the absolute biaryl configuration.
- Korb, Marcus,Schaarschmidt, Dieter,Grumbt, Martin,K?nig, Matthias,Lang, Heinrich
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supporting information
p. 2968 - 2982
(2020/07/02)
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- Ionic-Liquid Controlled Nitration of Double Bond: Highly Selective Synthesis of Nitrostyrenes and Benzonitriles
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Unprecedented in literature, the conversion of aryl alkenes into β-nitrostyrenes (2) or benzonitriles (3) with sodium nitrite can be governed by an appropriate choice of ionic liquid (IL) medium. A general trend was found for the selectivity of these processes, which depends on the nature of IL, with imidazolium-based ILs, such as [Bmim]Cl, that favor the C–H nitration leading to β-nitrostyrenes, while tetraalkylammonium-based ILs, such as TBAA, privilege the C=C bond cleavage affording benzonitriles. Besides a substrate scope, mechanistic hypotheses were provided on the origin of the different selectivity in the two kinds of ILs, based on their own tunable properties such as polarity, viscosity, and solvent cage effects.
- Casiello, Michele,Caputo, Daniela,Fusco, Caterina,Cotugno, Pietro,Rizzi, Vito,Dell'Anna, Maria Michela,D'Accolti, Lucia,Nacci, Angelo
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supporting information
p. 6012 - 6018
(2020/08/24)
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- Cyclotrimerization of alkynes catalyzed by a self-supported cyclic tri-nuclear nickel(0) complex with α-diimine ligands
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A cyclic tri-nuclear α-diimine nickel(0) complex [{Ni(μ-LMe-2,4)}3] (2) was synthesized from a “pre-organized”, trimerized trigonal LNiBr2-type precursor [Ni3(μ2-Br)3(μ3-Br)2(LMe-2,4)3]·Br (1; LMe-2,4 = [(2,4-Me2C6H3)NC(Me)]2). In complex 2, the α-diimine ligands not only exhibit the normal N,N′-chelating mode, but they also act as bridges between the Ni atoms through an unusual π-coordination of a C═N bond to Ni. Complex 2 is able to catalyze the cyclotrimerization of alkynes to form substituted benzenes in good yield and regio-selectivity for the 1,3,5-isomers, which is found to vary with the nature of the alkyne employed. This complex represents a convenient self-supported nickel(0) catalyst with no need for additional ligands and reducing agent.
- Shen, Lingyi,Zhao, Yanxia,Luo, Qiong,Li, Qian-Shu,Liu, Bin,Redshaw, Carl,Wu, Biao,Yang, Xiao-Juan
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supporting information
p. 4643 - 4649
(2019/04/05)
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- Iron-catalyzed regioselective cyclotrimerization of alkynes to benzenes
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We report the synthesis and characterization of simple di(aminomethyl)pyridine ligated iron-pincer complexes, which catalyzed the regioselective [2+2+2] cyclotrimerization of terminal aryl and alkyl alkynes to provide the 1,2,4-trisubstituted benzene molecules. Interestingly, internal alkynes also exhibited similar cyclization and resulted in hexa-substituted benzene compounds. Increased steric bulk on pincer ligands diminished the selectivity for cycloaddition. Cyclotrimerization reactions proceeded at room temperature upon activation of catalyst by a Grignard reagent. EPR studies indicated thermally induced spin crossover effect in catalyst.
- Gawali, Suhas Shahaji,Gunanathan, Chidambaram
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p. 139 - 149
(2019/01/03)
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- METHOD FOR PRODUCING BENZENE COMPOUND AND CATALYST FOR PRODUCING BENZENE COMPOUND
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PROBLEM TO BE SOLVED: To provide a method for producing a benzene compound capable of performing production of various benzene compounds with low environmental load without generating waste as in the case of using benzene as a starting raw material and to provide a catalyst used for the production method. SOLUTION: There are provided: a method for producing a benzene compound from alkynes in the presence of a catalyst, wherein the catalyst is a PdAu supported catalyst obtained by supporting Pd and Au in a molar ratio of 1:1 to 1:10 on a carrier; and a catalyst used for the production method. SELECTED DRAWING: None COPYRIGHT: (C)2019,JPOandINPIT
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-
Paragraph 0022; 0023-0030
(2019/03/02)
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- Synthesis and Reactivity of an Early-Transition-Metal Alkynyl Cubane Mn4C4 Cluster
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While the coordination chemistry of monometallic complexes and the surface properties of extended metal particles are well understood, the control of metal nanocluster formation has remained challenging. The isolation of discrete metal clusters provides an especially rare snapshot at the nanoscale of cluster growth. The synthesis and full characterization of the first early-transition-metal alkynyl cubane and the first μ3-alkynyl Mn3 motif are reported.
- Chakraborty, Uttam,Demeshko, Serhiy,Meyer, Franc,Jacobi von Wangelin, Axel
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supporting information
p. 3466 - 3470
(2019/02/20)
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- Application of zwitterionic phosphapalladacycles in aqueous phase Suzuki-Miyaura coupling
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The catalytic application of novel six-membered zwitterionic palladacycles with formal negative charge on the metal center and positive charge on the ancillary ligand is reported in the aqueous phase Suzuki-Miyaura coupling. The novel catalysts provide excellent activities with high functional group tolerance in the carbon-carbon bond forming reaction yielding substituted biaryls in high yields.
- Szi-Ferenc, László,Császár, Zsófia,Bényei, Attila,Bakos, József,Farkas, Gergely
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supporting information
p. 569 - 570
(2019/01/04)
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- Palladium-catalysed room-temperature Suzuki–Miyaura coupling in water extract of pomegranate ash, a bio-derived sustainable and renewable medium
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An agro waste-derived, ‘water extract of pomegranate ash’ (WEPA), has been utilized for the first time as a renewable medium for Pd(OAc)2-catalysed Suzuki–Miyaura cross-coupling at room temperature. This method offers a simple and sustainable synthesis of biaryls from aryl halides and arylboronic acids under ligand- and external base-free aerobic and ambient conditions. This method has been found effective for both activated and unactivated aryl halides in the production of biaryls with moderate to nearly quantitative yields. The protocol shows high chemoselectivity over identical/similar reactive sites in aryl halides (i.e. selectivity over identical halogens or different halogens of aryl halides). This method exhibits high regioselectivity, i.e. the selective reactivity of a halogen over other identical halogens at different positions on the aromatic nucleus. Therefore, we disclose here a clean, benign, substantial chemo- and regioselective and highly economic alternative method for the palladium-assisted synthesis of biaryls using an agro waste-derived medium.
- Appa, Rama Moorhy,Prasad, S. Siva,Lakshmidevi, Jangam,Naidu, Bandameeda Ramesh,Narasimhulu, Manchala,Venkateswarlu, Katta
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- Facile Synthesis of 1,3,5-Triarylbenzenes and 4-Aryl-NH-1,2,3-Triazoles Using Mesoporous Pd-MCM-41 as Reusable Catalyst
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We report mesoporous nano-Pd-MCM-41 catalyzed rapid and efficient synthesis of 1,3,5-triarylbenzenes via de-nitrative cyclotrimerization of β-nitrostyrenes. All the reactions were very fast and high yielding. The Pd-MCM-41 was also very effective in catalyzing de-nitrative [3+2] cycloaddition of β-nitrostyrenes with TMSN3 to synthesize 4-aryl-NH-1,2,3-triazoles. The catalyst was reused at least up to eight times with minimum loss of catalytic activity.
- Saha, Arijit,Wu, Chia-Ming,Peng, Rui,Koodali, Ranjit,Banerjee, Subhash
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p. 104 - 111
(2019/01/04)
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- Concerted Catalysis by Adjacent Palladium and Gold in Alloy Nanoparticles for the Versatile and Practical [2+2+2] Cycloaddition of Alkynes
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A Pd-Au alloy efficiently catalyzed the [2+2+2] cycloaddition of substituted alkynes. Whereas monometallic Pd and Au catalysts were totally ineffective, Pd-Au alloy nanoparticle catalysts with a low Pd/Au molar ratio showed high activity to give the corresponding polysubstituted arenes in high yields. A variety of substituted alkynes participated in various modes of cycloaddition under Pd-Au alloy catalysis. The Pd-Au alloy catalysts exhibited high air tolerance and reusability.
- Miura, Hiroki,Tanaka, Yumi,Nakahara, Karin,Hachiya, Yuka,Endo, Keisuke,Shishido, Tetsuya
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supporting information
p. 6136 - 6140
(2018/05/03)
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- A Manganese Nanosheet: New Cluster Topology and Catalysis
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While the coordination chemistry of monometallic complexes and the surface characteristics of larger metal particles are well understood, preparations of molecular metallic nanoclusters remain a great challenge. Discrete planar metal clusters constitute nanoscale snapshots of cluster growth but are especially rare owing to the strong preference for three-dimensional structures and rapid aggregation or decomposition. A simple ligand-exchange procedure has led to the formation of a novel heteroleptic Mn6 nanocluster that crystallized in an unprecedented flat-chair topology and exhibited unique magnetic and catalytic properties. Magnetic susceptibility studies documented strong electronic communication between the manganese ions. Reductive activation of the molecular Mn6 cluster enabled catalytic hydrogenations of alkenes, alkynes, and imines.
- Chakraborty, Uttam,Reyes-Rodriguez, Efrain,Demeshko, Serhiy,Meyer, Franc,Jacobi von Wangelin, Axel
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supporting information
p. 4970 - 4975
(2018/03/28)
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- Catalytic activity of a large Rhodium metallaborane towards the [2+2+2] cycloaddition of alkynes
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Rhodadecaborane [6-(η5-C5Me5)-nido-6-RhB9H13] (1) was found to be able to catalyze the [2+2+2] cycloaddition of a series of terminal and internal alkynes to yield mixtures of 1,2,4- and 1,3,5-substituted benzene. The reactivity of compound 1 with alkynes demonstrates that decaborane based metallaborane can be used as the catalyst for [2+2+2] cycloaddition of alkynes. All compounds are characterized by NMR spectroscopy and MS spectrometry methods.
- Ma, Pei,Spencer, James T.
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- Cyclotrimerization of phenylacetylene catalyzed by a cobalt half-sandwich complex embedded in an engineered variant of transmembrane protein FhuA
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An (η5-cyclopentadienyl)cobalt(i) complex was covalently incorporated into an engineered variant of the transmembrane protein ferric hydroxamate uptake protein component: A, FhuA ΔCVFtev, using a thiol-ene reaction. A CD spectrum shows the structural integrity of the biohybrid catalyst. MALDI-TOF of the segment containing the anchoring site for the cobalt complex Cys545 confirmed successful conjugation. This biohybrid catalyst catalyzed the cyclotrimerization of phenylacetylene to give a mixture of regioisomeric 1,2,4- and 1,3,5-triphenylbenzene in aqueous medium.
- Thiel,Sauer,Mertens,Polen,Chen,Schwaneberg,Okuda
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supporting information
p. 5452 - 5456
(2018/08/12)
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- Cobalt Octacarbonyl-Catalyzed Scalable Alkyne Cyclotrimerization and Crossed [2 + 2 + 2]-Cycloaddition Reaction in a Plug Flow Reactor
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Cobalt-catalyzed alkyne cyclotrimerization and crossed [2 + 2 + 2] cycloadditions are developed in a plug flow reactor. The protocol generally uses 5 mol % of Co2(CO)8 and is scalable at least at multigram scale. Efficient and scalable use of Co2(CO)8 for crossed reactions of diynes and alkynes has hardly any precedent.
- García-Lacuna, Jorge,Domínguez, Gema,Blanco-Urgoiti, Jaime,Pérez-Castells, Javier
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p. 5219 - 5223
(2018/09/13)
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- Alkyne [2 + 2 + 2] Cyclotrimerization Catalyzed by a Low-Valent Titanium Reagent Derived from CpTiX3 (X = Cl, O- i-Pr), Me3SiCl, and Mg or Zn
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Inter-, partially intra-, and intramolecular [2 + 2 + 2] cycloadditions of alkynes were catalyzed by a low-valent titanium species generated in situ from the reduction of CpTi(O-i-Pr)3, CpTiCl3, or Cp?TiCl3 with Mg or Zn powder in the presence of Me3SiCl. The role of Me3SiCl as an additive in the reaction mechanism is discussed.
- Okamoto, Sentaro,Yamada, Takeshi,Tanabe, Yu-Ki,Sakai, Masaki
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p. 4431 - 4438
(2019/01/03)
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- Can the Ti(OiPr)4/nBuLi combination of reagents function as a catalyst for [2+2+2] alkyne cyclotrimerisation reactions?
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Catalysis of the cyclotrimerisation of alkynes with the Ti(OiPr)4/nBuLi system was studied, leading to the development of a particularly convenient and reliable protocol. This method allows the [2+2+2] cycloaddition reaction to proceed within a few minutes under microwave conditions, with generally good selectivity from a variety of aromatic and aliphatic alkynes.
- Siemiaszko, Gabriela,Six, Yvan
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supporting information
p. 20219 - 20226
(2018/12/13)
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- Olefin-Stabilized Cobalt Nanoparticles for C=C, C=O, and C=N Hydrogenations
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The development of cobalt catalysts that combine easy accessibility and high selectivity constitutes a promising approach to the replacement of noble-metal catalysts in hydrogenation reactions. This report introduces a user-friendly protocol that avoids complex ligands, hazardous reductants, special reaction conditions, and the formation of highly unstable pre-catalysts. Reduction of CoBr2 with LiEt3BH in the presence of alkenes led to the formation of hydrogenation catalysts that effected clean conversions of alkenes, carbonyls, imines, and heteroarenes at mild conditions (3 mol % cat., 2–10 bar H2, 20–80 °C). Poisoning studies and nanoparticle characterization by TEM, EDX, and DLS supported the notion of a heterotopic catalysis mechanism.
- Sandl, Sebastian,Schwarzhuber, Felix,P?llath, Simon,Zweck, Josef,Jacobi von Wangelin, Axel
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supporting information
p. 3403 - 3407
(2018/02/13)
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- Preliminary results of the reaction of cyclotrimerization of phenylacetylene [2+2+2] catalyzed by [(Cp?)Co(Indene)] complex
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This work describes the catalytic study of [(Cp?)Co(Ind)] (with Cp?= pentamethylcyclopentadienyl, Ind= Indenyl, (C9H7)) complex in cyclotrimerization of phenylacetylene. From the cylcotrimerization reaction was possible to obtain products such as substituted pyridines 2-methyl-3,5-diphenylpyridine (3), 2-methyl- 4,6-diphenylpyridine (4) and the compound 1,2,4-triphenylbenzene (5) using acetonitrile as solvent. On the other hand, using toluene as solvent under the same working conditions, the product of reaction was 1,3,5-triphenylbenzene (1). Furthermore, by varying the working conditions, the reaction is 90% selective towards the formation of pyridines. In addition, has been appreciated the formation of another product 1,4-diphenilbuta-1,3-diyne (2), which was isolated and characterized by means NMR and GC-Mass spectrometry.
- Morales-Verdejo, Cesar,Camarada, María Belén,Morales, Verónica,Ca?ete, álvaro,Martínez, Iván,Manriquez, Juan Manuel,Chávez, Ivonne
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p. 3898 - 3901
(2018/05/24)
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- Sulfurative self-condensation of ketones and elemental sulfur: A three-component access to thiophenes catalyzed by aniline acid-base conjugate pairs
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A sulfurative self-condensation method for constructing thiophenes 2 by a reaction between ketones 1 and elemental sulfur is reported. This reaction, which is catalyzed by anilines and their salts with strong acids, starts from readily available and inexp
- Nguyen, Thanh Binh,Retailleau, Pascal
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p. 387 - 390
(2018/02/07)
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- Electrical and electrochemical properties of lithium solvated electron solutions derived from 1,3,5-triphenylbenzenes
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A series of 1,3,5-triphenylbenzenes (TPBs) bearing various substituents have been made and their ability to form lithium solvated electron solutions (LiSESs) in tetrahydrofuran (THF) solution have been studied. It was found that the TPBs bearing electron
- Lunchev, Andrey V.,Tan, Kim Seng,Grimsdale, Andrew C.,Yazami, Rachid
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supporting information
p. 15678 - 15683
(2018/10/04)
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- Efficient Synthesis of Functionalized 4 H -Chromenes via an Fe(OTf) 3 -Catalyzed Cyclization Reaction of Phenols and Ketones
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The iron(III) triflate catalyzed cyclization reaction of phenols and ketones is described; the reaction provides a direct approach to 4 H -chromene derivatives. 4 H -Chromene is an important structural fragment of many pharmaceuticals, natural products, and functional materials. The 4 H -chromene synthetic protocol possesses many advantages, such as using readily available and inexpensive starting materials and a non-toxic catalyst, high selectivity, and operational simplicity, which offer attractive industrial prospects from the point of view of green and sustainable chemistry.
- Deng, Kai,Huai, Qi-Yong,Li, Hui-Jing,Wang, Jun-Hu,Yang, Hui-Ru,Liu, Ying,Wu, Yan-Chao
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p. 1482 - 1492
(2018/03/26)
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- The Highly Efficient Suzuki–Miyaura Cross-Coupling of (Hetero)aryl Chlorides and (Hetero)arylboronic Acids Catalyzed by “Bulky-yet-Flexible” Palladium–PEPPSI Complexes in Air
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A series of Pd–PEPPSI complexes were designed and synthesized. The relationship between catalyst structure and properties was systematically investigated. It was revealed that “bulky-yet-flexible” C3 bearing ancenaphthyl backbone was a highly efficient precatalyst and could be successfully employed in Suzuki–Miyaura reactions of (hetero)aryl chlorides with (hetero)arylboronic acids at a low palladium loading in the presence of a weak inorganic base in air.
- Ouyang, Jia-Sheng,Li, Yan-Fang,Huang, Fei-Dong,Lu, Dong-Dong,Liu, Feng-Shou
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p. 371 - 375
(2017/12/15)
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- Desulfinative and denitrogenative palladium-catalyzed cross-coupling of arylsulfonyl hydrazides with aryl diazonium salts
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Palladium-catalyzed cross-coupling of arylsulfonyl hydrazides with aryl diazonium salts to provide biaryl products under relatively mild conditions is established. This reaction proceeded smoothly with tetrabutylammonium iodide and gave the corresponding
- Shang, Yonghui
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- Air-Stable Blue Phosphorescent Tetradentate Platinum(II) Complexes as Strong Photo-Reductant
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Strong photo-reductants have applications in photo-redox organic synthesis involving reductive activation of C?X(halide) and C=O bonds. We report herein air-stable PtII complexes supported by tetradentate bis(phenolate-NHC) ligands having peripheral electron-donating N-carbazolyl groups. Photo-physical, electrochemical, and computational studies reveal that the presence of N-carbazolyl groups enhances the light absorption and redox reversibility because of its involvement into the frontier MOs in both ground and excited states, making the complexes robust strong photo-reductant with E([Pt]+/*) over ?2.6 V vs. Cp2Fe+/0. The one-electron reduced [Pt]? species are stronger reductants with EPC([Pt]0/?) up to ?3.1 V vs. Cp2Fe+/0. By virtue of the strong reducing nature of these species generated upon light excitation, they can be used in light-driven reductive coupling of carbonyl compounds and reductive debromination of a wide range of unactivated aryl bromides.
- Li, Kai,Wan, Qingyun,Yang, Chen,Chang, Xiao-Yong,Low, Kam-Hung,Che, Chi-Ming
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supporting information
p. 14129 - 14133
(2018/10/15)
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- DBU-Mediated Construction of 1,3,5-Trisubstituted Benzenes via Annulation of α,β-Unsaturated Carboxylic Acids and α-Cyano-β-methylenones
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A DBU-mediated synthesis of 1,3,5-trisubstituted benzenes was developed via the [2 + 4] annulation of in situ activated α,β-unsaturated carboxylic acids and α-cyano-β-methylenones. The dual role of DBU as Br?nsted base and nucleophilic Lewis base is the key for the success of the reaction.
- Zhang, Chun-Lin,Zhang, Zhao-Fei,Xia, Zi-Hao,Han, You-Feng,Ye, Song
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p. 12507 - 12513
(2018/10/20)
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- Synthesis of α-pyrones by catalytic oxidative coupling of terminal alkynes and carbon dioxide
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The use of the complex [(dippe)Ni(μ-H)]2(1) as a catalyst precursor (10?mol%) in the presence of a variety of terminal alkynes and CO2allowed the production of substituted α–pyrones. This reaction occurs using relatively mild conditions (50?°C, 150 psi of CO2) with good to modest yields, depending on the nature of the substituents in the corresponding alkyne. The produced α–pyrones were characterized by different analytical methods and spectroscopic techniques.
- Oliveros-Cruz, Saray,Arévalo, Alma,García, Juventino J.
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- Insight into the Activation of In Situ Generated Chiral RhI Catalysts and Their Application in Cyclotrimerizations
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We report a detailed study concerning the efficient generation of highly active chiral rhodium complexes of the general structure [Rh(diphosphine)(solvent)2]+ as well as their exemplary successful utilization as catalysts for cyclotrimerizations. Such solvent complexes could likewise be prepared from novel ammonia complexes of the type [Rh(diphosphine)(NH3)2]+. A valuable, feasible approach to generate novel chiral RhI complexes was found by in situ generation from Wilkinson's catalyst [RhCl(PPh3)3] with chiral P,N ligands. The generated catalysts led to moderate to good enantioselectivities and excellent yields in the cyclotrimerizations of triynes, showcasing their usefulness in the synthesis of axially chiral benzene derivatives.
- Thiel, Indre,Horstmann, Moritz,Jungk, Phillip,Keller, Sonja,Fischer, Fabian,Drexler, Hans-Joachim,Heller, Detlef,Hapke, Marko
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p. 17048 - 17057
(2017/11/16)
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- Divergent reactivity of a new dinuclear xanthene-bridged bis(iminopyridine) di-nickel complex with alkynes
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The reaction of a dinucleating bis(iminopyridine) ligand L bearing a xanthene linker (L = N,N′-(2,7-di-tert-butyl-9,9-dimethyl-9H-xanthene-4,5-diyl)bis(1-(pyridin-2-yl)methanimine)) with Ni2(COD)2(DPA) (COD = cyclooctadiene, DPA = diphenylacetylene) leads to the formation of a new dinuclear complex Ni2(L)(DPA). Ni2(L)(DPA) can also be obtained in a one-pot reaction involving Ni(COD)2, DPA and L. The X-ray structure of Ni2(L)(DPA) reveals two square-planar Ni centers bridged by a DPA ligand. DFT calculations suggest that this species features NiI centers antiferromagnetically coupled to each other and their iminopyridine ligand radicals. Treatment of Ni2(L)(DPA) with one equivalent of ethyl propiolate (HCCCO2Et) forms the Ni2(L)(HCCCO2Et) complex. Addition of the second equivalent of ethyl propiolate leads to the observation of cyclotrimerised products by 1H NMR spectroscopy. Carrying out the reaction under catalytic conditions (1 mol% of Ni2(L)(DPA), 24 h, room temperature) transforms 89% of the substrate, forming primarily benzene products (triethyl benzene-1,2,4-tricarboxylate and triethyl benzene-1,3,5-tricarboxylate) in 68% yield, in a ca. 5:1 relative ratio. Increasing catalyst loading to 5 mol% leads to the full conversion of ethyl propiolate to benzene products; no cyclotetramerisation products were observed. In contrast, the reaction is significantly more sluggish with methyl propargyl ether. Using 1 mol% of the catalyst, only 25% conversion of methyl propargyl ether was observed within 24 h at room temperature. Furthermore, methyl propargyl ether demonstrates the formation of cyclooctatetraenes in significant amounts at a low catalyst concentration, whereas a higher catalyst concentration (5 mol%) leads to benzene products exclusively. Density functional theory was used to provide insight into the reaction mechanism, including structures of putative dinuclear metallocyclopentadiene and metallocycloheptatriene intermediates.
- Hollingsworth, Ryan L.,Bheemaraju, Amarnath,Lenca, Nicole,Lord, Richard L.,Groysman, Stanislav
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p. 5605 - 5616
(2017/07/10)
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- Iron-Catalyzed Cyclotrimerization of Terminal Alkynes by Dual Catalyst Activation in the Absence of Reductants
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Catalyzing C?C bond-forming reactions with earth-abundant metals under mild conditions is at the heart of sustainable synthesis. The cyclotrimerization of alkynes is a valuable atom-efficient reaction in organic synthesis that is enabled by several metal catalysts, including iron. This study reports an effective iron-catalyzed cyclotrimerization for the regioselective synthesis of 1,2,4-substituted arenes (1 mol % catalyst, toluene, 20 °C, 5 min). A dual activation mechanism (substrate deprotonation, reductive elimination) renders the simple FeII precatalyst highly active in the absence of any reductant.
- Brenna, Davide,Villa, Matteo,Gieshoff, Tim N.,Fischer, Fabian,Hapke, Marko,Jacobi von Wangelin, Axel
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supporting information
p. 8451 - 8454
(2017/07/11)
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- Synthesis, characterization and catalytic application of some novel PNP-Ni(II) complexes: Regio-selective [2+2+2] cycloaddition reaction of alkyne
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Some novel Ni(II) complexes of PN(H)PPh, PN(Me)PiPr and PN(Me)PtBu ligands have been synthesized and characterized using standard analytical and spectroscopic methods such as 1H NMR, 31P NMR, elemental analysis, ESI-MS, UV-Visible spectroscopy and single-crystal X-ray crystallography. In the presence of silver triflate, complex [PN(H)PPhNiBr]2NiBr4 (5) activated the C?Cl bond of dichloromethane at room temperature and afford complex [PN(H)PPhNiCl]OTf (6). We have also performed alkyne [2+2+2] cycloaddition reaction using Ni(II) complexes and observed high regioselectivity of the products. The observed selectivity is well correlating with the electronic feature of alkynes. The [2+2+2] cycloaddition of electron rich alkynes produced 1,3,5-substituted benzene derivatives as a major product whereas the electron deficient alkynes produced 1,2,4-substituted benzene derivatives as a major product.
- Tamizmani, Masilamani,Sivasankar, Chinnappan
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- Pd and Ni complexes of a novel vinylidene β-diketimine ligand: Their application as catalysts in Heck coupling and alkyne trimerization
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A β-diketimine ligand with vinylidene substitution at γ-carbon, CH2C(CH3CNAr)2 (Ar?=?2,6-diisopropylphenyl) (L2), was synthesized by treating β-diketimine H2C(CH3CNAr)2 with n-BuLi followed by paraformaldehyde. L2 formed the homobimetallic ether-bridged β-diketiminate complex [O{(CH2-β-diketiminate)Pd(OAc)}2] (1) with (PdOAc)2. It also gave complexes [L2PdCl2] (2) and [L2NiBr2] (3) when treated with PdCl2(CH3CN)2 and NiBr2(dimethoxyethane), respectively. All the compounds were characterized using 1H/13C NMR spectroscopy and single-crystal X-ray diffraction studies. The catalytic activity of Pd and Ni complexes 1, 2 and 3 was explored in Heck coupling and alkyne trimerization reactions and it was found that they are very good catalysts. The results are reported in detail.
- Beesam, Raghavendra,Nareddula, Dastagiri Reddy
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- Reversible Cleavage/Formation of the Chromium–Chromium Quintuple Bond in the Highly Regioselective Alkyne Cyclotrimerization
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Herein we report the employment of the quintuply bonded dichromium amidinates [Cr{κ2-HC(N-2,6-iPr2C6H3)(N-2,6-R2C6H3)}]2 (R=iPr (1), Me (7)) as catalysts to mediate the [2+2+2] cyclotrimerization of terminal alkynes giving 1,3,5-trisubstituted benzenes. During the catalysis, the ultrashort Cr?Cr quintuple bond underwent reversible cleavage/formation, corroborated by the characterization of two inverted arene sandwich dichromium complexes (μ-η6:η6-1,3,5-(Me3Si)3C6H3)[Cr{κ2-HC(N-2,6-iPr2C6H3)(N-2,6-R2C6H3)}]2 (R=iPr (5), Me (8)). In the presence of σ donors, such as THF and 2,4,6-Me3C6H2CN, the bridging arene 1,3,5-(Me3Si)3C6H3 in 5 and 8 was extruded and 1 and 7 were regenerated. Theoretical calculations were employed to disclose the reaction pathways of these highly regioselective [2+2+2] cylcotrimerization reactions of terminal alkynes.
- Huang, Yu-Siang,Huang, Gou-Tao,Liu, Yao-Lun,Yu, Jen-Shiang K.,Tsai, Yi-Chou
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supporting information
p. 15427 - 15431
(2017/11/10)
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- Synthesis of zwitterionic palladium complexes and their application as catalysts in cross-coupling reactions of aryl, heteroaryl and benzyl bromides with organoboron reagents in neat water
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N-(3-Chloro-2-quinoxalinyl)-N′-arylimidazolium salts (aryl = 2,6-diisopropylphenyl [HL1Cl]Cl, aryl = mesityl [HL2Cl]Cl) have been synthesized by treating 2,3-dichloroquinoxaline with the corresponding N′-arylimidazole in neat water. Facile reactions of these imidazolium salts with Pd(PPh3)4 and Pd2(dba)3/PPh3 (dba = dibenzyledene acetone) at 50 °C have afforded zwitterionic palladium(ii) complexes [Pd(HL1)(PPh3)Cl2] (I) and [Pd(HL2)(PPh3)Cl2] (II) in excellent yields. I and II have been tested for their ability to catalyze Suzuki-Miyaura cross coupling (SMC) reactions in neat water/K2CO3 and are found to be highly active for carrying out these reactions between aryl bromides and organoboron reagents. Furthermore, the scope of the catalyst I was also examined by employing (hetero)aryl bromides, hydrophilic aryl bromides, benzyl bromides and various organoboron reagents. More than 80 aryl/benzyl bromide-arylboronic acid combinations were screened in neat water/K2CO3 and it was found that I was a versatile catalyst, which produced biaryls/diarylmethanes in excellent yields. A TON of 82 000 was achieved by using I. Studies on the mechanism have also been carried out to investigate the involvement of carbene complexes in the catalytic path. Poison tests and a two-phase test were also conducted and the results are reported.
- Ramakrishna,Dastagiri Reddy
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supporting information
p. 8598 - 8610
(2017/07/12)
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- Sulfated tungstate catalyzed synthesis of C3-symmetric 1,3,5-triaryl benzenes under solvent-free condition
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Sulfated tungstate catalyzed environmentally benign, simple, one pot, and solvent-free method has been developed for the synthesis of 1,3,5-triarylbenzenes via cyclic self-condensation of three molecules of aryl ketones. High yields, short reaction time, easy work-up procedure and recycling of the catalyst endorse advantage.
- Wagh, Ganesh D.,Akamanchi, Krishnacharya G.
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supporting information
p. 3032 - 3036
(2017/07/17)
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- Method for preparing 1,3,5-triphenylbenzene compound
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The invention relates to a method for synthesizing a 1,3,5-triphenylbenzene compound. The 1,3,5-triphenylbenzene compound has a structure as shown in figure 1, wherein R1, R2, R3 R4 and R5 are hydrogen atom, alkyl, aryl, halogen, alkoxy, amidogen andtrifl
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Paragraph 0006
(2017/09/01)
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