- Pinpoint-fluorinated phenanthrene synthesis based on C-F bond activation of difluoroalkenes Dedicated to Prof. Véronique Gouverneur on the occasion of her receipt of the 2014 ACS Award for Creative Work in Fluorine Chemistry.
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Treatment with a cationic palladium(II) catalyst promoted the Friedel-Crafts-type cyclization of 1,1-difluoro-1-alkenes bearing a biphenyl skeleton to afford regioselectively fluorinated (pinpoint-fluorinated) phenanthrenes via C-F bond activation. The obtained pinpoint-fluorinated phenanthrenes were observed to be organized by π-π and C-H?F interactions to exhibit columnar and layer structures in the solid state.
- Fuchibe, Kohei,Morikawa, Toshiyuki,Ueda, Ryu,Okauchi, Tatsuo,Ichikawa, Junji
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- Annulation selectivity in the coupling of Fischer carbene complexes with o-alkynylbiphenyl and o-alkynylstyrene derivatives
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The coupling of various Fischer carbene complexes with o-ethynylbiphenyl and an o-alkynylstyrene derivatives has been examined. In coupling reactions with methylcarbene and cyclopropylcarbene complexes, the major products are derived from C-H or C-C activation processes. In coupling reactions with phenylcarbene complexes, the major products are derived from the D?tz reaction.
- Jackson, Thaddeus J,Herndon, James W
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- Suzuki-Miyaura and Hiyama reactions catalyzed by orthopalladated triarylphosphite complexes
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Orthometallated, dimeric, and monomeric palladium complexes with triphenylphoshito ligands and square-planar complexes of the type PdCl 2[P(OR)3]2 (where R=Ph, m-MeC6H 4, o-MeC6H4, C6H3-2,4- tBu2) were applied in the Suzuki-Miyaura and the Hiyama reactions leading to the same product, 2-Mebiphenyl. The desired product was obtained in high yield in reactions performed in ethane-1,2-diol with Cs 2CO3 as a base. The optimized procedure was also applied to the synthesis of other biphenyl derivatives, and in most cases the Suzuki-Miyaura procedure led to higher yields of the product.
- B?aszczyk, Izabela,Trzeciak, Anna M.
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- Macroporous resin impregnated palladium nanoparticles: Catalyst for a microwave-assisted green Hiyama reaction
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A non-functional macroporous commercial resin, Amberlite XAD-4, was impregnated with palladium nanoparticles of size 5-10 nm. The supported PdNPs, thus prepared, were used to catalyze the sodium hydroxide activated Hiyama cross-coupling reaction of phenyltrimethoxysilane with a variety of bromo and chloro arenes under microwave heating. They were found to have very high efficiency (TOF ≈ 3 × 104) and excellent recyclability. The procedure, which was carried out in the absence of any additional ligands, surfactants or toxic organic solvents, can lead to the development of a sustainable and green protocol for the production of biaryls.
- Shah, Dipen,Kaur, Harjinder
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- Cu(OAc)2-catalyzed coupling of aromatic C-H bonds with arylboron reagents
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Cu-catalyzed coupling of aryl C-H bonds with arylboron reagents was accomplished using a readily removable directing group, which provides a useful method for the synthesis of biaryl compounds. The distinct transmetalation step in this Cu-catalyzed C-H coupling with aryl borons provides unique evidence for the formation of an aryl cupperate intermediate.
- Shang, Ming,Sun, Shang-Zheng,Dai, Hui-Xiong,Yu, Jin-Quan
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- (Biphenyl-2-alkyne) derivatives as common precursors for the synthesis of 9-iodo-10-organochalcogen-phenanthrenes and 9-organochalcogen-phenanthrenes
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In this paper, we report our results on the cyclization of (biphenyl-2-alkyne) derivatives to give two different types of phenanthrene derivatives, 9-iodo-10-organochalcogen-phenanthrenes and 9-organochalcogen-phenanthrenes. The strategy for the synthesis was based on the use of electrophilic cyclization for the preparation of 9-iodo-10-organochalcogen-phenanthrenes and iron(iii) chloride/diorganyl diselenide-mediated intramolecular cyclization to prepare 9-organochalcogen-phenanthrenes. The effects of solvent, temperature, reaction time and stoichiometry on the efficiency of cyclization reactions were investigated. The standard reaction conditions were compatible with many functional groups in the substrates, such as methyl, chlorine, fluorine and methoxyl. This protocol was efficient for diorganyl diselenides and disulfides but ineffective for diorganyl ditellurides. The resulting phenanthrenes were further functionalized through Sonogashira reactions followed by the electrophilic cyclization reaction to give the selenophene-fused aromatic compounds.
- Grimaldi, Tamiris B.,Lutz, Guilherme,Back, Davi F.,Zeni, Gilson
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- Palladium catalysed cross-coupling of aryl chlorides with arylboronic acids in the presence of a new tetraphosphine ligand
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Cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclo pentane/[PdCl(C3H5)]2 system catalyses the cross-coupling of aryl chlorides with arylboronic acids with high ratios substrate/catalyst. A turnover number of 6800000 has been obtained for the addition of the activated 2-chloro-5-(trifluoromethyl)nitrobenzene to benzeneboronic acid in the presence of this catalyst.
- Feuerstein,Doucet,Santelli
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- PHOTODEGRADATION OF PHENANTHRENE IN THE PRESENCE OF HUMIC SUBSTANCES AND HYDROGEN PEROXIDE
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The photodegradation of phenanthrene in water was investigated for a variety of reaction conditions employing various fulvic acids (FAs) as photosensitizers and hydrogen peroxide as oxidant. All experiments were conducted by using artificial sunlight from Suntest apparatus (Hanau, Germany) as light source. The relative rates of phenanthrene photodegradation for the different experimental conditions were computed. Fulvic acids of different origins influenced the rate of sunlight-induced photodegradation of phenanthrene in different ways. Hydrogen peroxide vigorously enhanced the photodegradation rate of phenanthrene. The photoproducts identified were oxygenated products of aromatic ring, such as 9,10-phenanthrenquinone, a group of hydroxyphenanthrene with hydroxyl at different position (1, 3, 4, and 9), 2,2'biphenyldicarbonic acid, 2,2'-biphenyldialdehyde and 2-phenylbenzaldehyde. It can be consumed that the phenanthrene photodegraded via free radical mechanism. - Keywords: Phenanthrene; Photodegradation; Fulvic Acids; Hydrogen Peroxide; Interaction
- Wang, C. X.,Yediler, A.,Peng, A.,Kettrup, A.
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- Restricted rotation in (phenylpyrrolidino)fullerene derivatives
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A complete series of (phenylpyrrolidino)fullerene derivatives has been prepared. A detailed conformational analysis of these compounds has been carried out by variable-temperature 1H NMR experiments and computational studies. In the case of (phenylpyrrolidino)fullerene derivatives without ortho substituents, dynamic phenomena arising from restricted rotation around the phenyl-pyrrolidine bond are observed. In contrast, as soon as one of the ortho positions of the phenyl ring is substituted, the rotational energy barrier is high enough to prevent observation under our experimental conditions (room temperature to 120°C) of any dynamic exchange resulting from rotation of the phenyl substituent on the pyrrolidine ring. Whereas, in principle, two diastereoisomeric conformers can exist for the ortho-substituted (phenylpyrrolidino)fullerenes, only the atropisomers in which the unsubstituted ortho position is located atop the fullerene sphere are obtained. We conclude that the reaction of the ortho-substituted benzaldehyde derivatives with C 60 is diastereoselective, affording only one of the two possible atropisomers. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
- Ajamaa, Fettah,Duarte, Teresa M. Figueira,Bourgogne, Cyril,Holler, Michel,Fowler, Patrick W.,Nierengarten, Jean-Francois
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- Convenient synthesis of palladium nanoparticles and catalysis of hiyama coupling reaction in water
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An efficient synthesis of Pd nanoparticles in water has been developed using a Fischer carbene complex of tungsten as the reductant and PEG as the capping agent. The colloidal palladium (1 mol %) efficiently catalyzes Hiyama cross-coupling reactions performed in air. Excellent yields of products were obtained with a wide range of substrates. Catalytic activity and stability of the nanoparticles were found to be inversely correlated.
- Srimani, Dipankar,Sawoo, Sudeshna,Sarkar, Amitabha
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- Homoleptic chelating N-heterocyclic carbene complexes of palladium immobilized within the pores of SBA-15/IL (NHC-Pd@SBA-15/IL) as heterogeneous catalyst for Hiyama reaction
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In this work, SBA-15 was selected as a support for the homoleptic chelating N-heterocyclic carbene complexes of palladium. Here, Pd2+ ions were coordinated to N-heterocyclic carbene (NHC-Pd) which also contain ionic liquid. Then, this NHC-Pd@SBA-15/IL catalyst (NHC-Pd active part of the catalyst) was successfully applied in the catalysis of Hiyama coupling reaction with lower mol% Pd rather to previously reported literatures. The role of TBAF and Cs2CO3 in the decrease of Pd mol% was crucial. Recyclability test showed a successful reusability for 5 runs. Simultaneous application of TBAF and NaOH did destroy the silica structure of SBA-15 in the first run.
- Rostamnia, Sadegh,Golchin Hossieni, Habib,Doustkhah, Esmail
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- Green conditions for the Suzuki reaction using microwave irradiation and a new HNT-supported ionic liquid-like phase (HNT-SILLP) catalyst
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A new catalytic system based on modified halloysite nanotubes was employed in the Suzuki reaction under microwave irradiation. A set of solvents, times and bases was screened and the best experimental conditions were obtained when the reactions were carried out for 10 min in water-ethanol at 120 °C in presence of K2CO3 as base. Good recyclability was observed. The new catalytic system was employed using either 1 mol% or 0.1 mol%. The palladium catalyst displayed good activity, allowing the synthesis of several biphenyl compounds in high yield working with only 0.1 mol% palladium loading. The application of microwave irradiation decreased the reaction time and also improved conversion with respect to traditional heating. Copyright
- Massaro, Marina,Riela, Serena,Lazzara, Giuseppe,Gruttadauria, Michelangelo,Milioto, Stefana,Noto, Renato
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- Carbon dot reduced palladium nanoparticles as active catalysts for carbon-carbon bond formation
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Carbon dots were used as a reducing agent for the synthesis of Pd nanoparticles coated with ultrathin carbon dot shells of ca. 4 nm. The resulting composite nanoparticles showed high catalytic activity for the Heck and Suzuki coupling reactions.
- Dey, Deepa,Bhattacharya, Tamalika,Majumdar, Biju,Mandani, Sonam,Sharma, Bhagwati,Sarma, Tridib K.
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- Bidentate organochalcogen ligands (N, E; E = S/Se) as stabilizers for recyclable palladium nanoparticles and their application in Suzuki–Miyaura coupling reactions
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Chalcogeno-substituted secondary amines L1 and L2 have been synthesized by the reduction of corresponding imines. Ligands L1 and L2 have been characterized using 1H and 13C{1H} NMR spectroscopy. The Schiff base precursors used for the synthesis of L1 has also been characterized using single crystal x-ray diffraction technique. Both the ligands (L1 and L2) have been used as stabilizers for palladium nanoparticles (PdNPs) 1–4 in two different ratios of Pd:L (1:1 and 1:4). The NPs have been characterized by UV–Vis spectroscopy, powder X-ray diffraction, scanning electron microscopy (SEM), SEM-EDX, and transmission electron microscopy (TEM). The chalcogen donor site showed remarkable role in the stabilization of these nanoparticles. The Pd:L ratio in NPs has been noticed to affect the size and shape of particles and also their catalytic behavior. Size of the NPs has been found to be in a range of 2–3 nm (NPs 1); 4–5 nm (NPs 2); 3–4 nm (NPs 3); and 4–6 nm (NPs 4). When explored as catalyst, the low loading of these NPs gave significant conversions for the coupling of various aryl halides with phenylboronic acid (Suzuki–Miyaura coupling) in a short reaction time of 3 h. The highest catalytic activity has been observed for Pd NPs 1 (Pd:L ratio 1:1) due to the uniformity in the dispersion of particles. The distinct advantage associated with these NPs (1–4) is that they retain catalytic activity after the reaction and are recyclable up to three times. Attempts were made to gain mechanistic insights of catalysis and it was found that both homogeneous and heterogeneous catalytic processes contribute to the catalysis.
- Sharma, Pratibha,Arora, Aayushi,Oswal, Preeti,Rao,Kaushal,Kumar, Sushil,Kumar, Satyendra,Singh,Kumar Singh, Ajai,Kumar, Arun
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- Chromium-Catalyzed, Regioselective Cross-Coupling of C-O Bonds by Using Organic Bromides as Reactants
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We report a chromium-catalyzed cross-coupling of C-O bonds with widely accessible organic bromides as reactants for the preparation of ortho -arylated or -alkylated aromatic aldehydes at room temperature. The use of metallic magnesium is essential for the reaction to occur, giving it an advantage over previous reactions involving Grignard reagents that have to be prepared separately from organic halides before the coupling.
- Tang, Jinghua,Luo, Meiming,Zeng, Xiaoming
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- Suzuki cross-coupling mediated by tetradentate N-heterocyclic carbene (NHC)-palladium complexes in an environmentally benign solvent
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A highly effective, easy to handle and environmentally benign process for palladium mediated Suzuki cross-coupling was developed. By utilizing a solid support based NHC-palladium catalyst, cross couplings of aryl bromides with phenylboronic acid were achieved in neat water under air. A high ratio of substrate to catalyst was also realized.
- Zhao, Yuanhong,Zhou, Yongyun,Ma, Dandan,Liu, Jingping,Li, Liang,Zhang,Zhang, Hongbin
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- Suzuki-Miyaura, Mizoroki-Heck carbon-carbon coupling and hydrogenation reactions catalysed by PdII and RhI complexes containing cyclodiphosphazane cis-{tBuNP(OC6H4OMe-o)} 2
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The catalytic activity of the palladium complex cis-[PdCl 2{(tBuNP(OC6H4OMe-o)) 2-κP}2] (2) containing cis-{tBuNP(OC 6H4OMe-o)}2 (1) in Suzuki-Miyaura and Mizoroki-Heck carbon-carbon cross coupling reactions is described. The compound 2 also displays very high activity in Mizoroki-Heck coupling reactions. The rhodium(I) complex [RhCl(COD){(tBuNP(OC6H 4OMe-o))2-κP}] (3) acts as an excellent catalyst for the hydrogenation of several terminal olefins. Indian Academy of Sciences.
- Mohanty, Sasmita,Balakrishna, Maravanji S.
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- An unsymmetrical Schiff-base derived recyclable Pd-catalyst for Suzuki–Miyaura and Sonogashira reactions in aqueous media
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Abstract: A water-soluble palladium (II) complex containing an unsymmetrical Schiff-base ligand was synthesized and applied as catalyst Suzuki–Miyaura and Sonogashira cross-coupling reactions in aqueous media. Notably, moderate to excellent yields of biaryls were obtained in Suzuki reaction with usually less reactive aryl and heteroaryl chlorides under relatively mild condition. Moderate-to-high yields of aryl-alkynes were also obtained in Sonogashira reactions using aryl bromides. Apart from hydrophilic nature, the accomplishment of reactions in water, high recyclability, broad functional group tolerance, etc., are other advantages of the system. Graphic abstract: [Figure not available: see fulltext.]
- Das, Pankaj,Gogoi, Achinta,Puzari, Amlan
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- Pd nanoparticles on a porous ionic copolymer: A highly active and recyclable catalyst for Suzuki-Miyaura reaction under air in water
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A porous copolymer of an IL with divinylbenzene was prepared and applied as a support for Pd nanoparticles. The supported Pd nanocatalyst was found to be extremely active for Suzuki-Miyaura reaction of aryl bromides and chlorides with phenylboronic acid even with 10 ppm Pd loading under air in water.
- Yu, Yanpeng,Hu, Tongjie,Chen, Xiaorong,Xu, Kunling,Zhang, Junli,Huang, Jun
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- Nucleophilic aromatic substitution on aromatic aldimines
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Ortho-methoxy-substituted benzaldimines derived from 3-amino-2,4-dimethylpentane undergo efficient nucleophilic aromatic substitution with typical organolithium reagents. The aldimine products can be hydrolyzed under mild conditions to provide ortho-alkyl or ortho-phenyl benzaldehyde derivatives.
- Flippin, Lee A.,Carter, David S.,Dubree, Nathan J. P.
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- Efficient ligand-free Hiyama cross-coupling reaction catalyzed by functionalized SBA-15-supported Pd nanoparticles
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A ligand-free Hiyama cross-coupling reaction catalyzed by functionalized SBA-15-supported Pd catalysts has been developed. The catalysts were prepared by depositing Pd nanoparticles preferentially in the micropores of the SBA-15 with hydrophobic trimethylsilyl or triphenylsilyl groups grafted on the mesopores. The nanocomposite catalysts showed excellent activities for the cross-coupling between various aryltriethoxysilanes and aryl halides under relatively mild (at 100 °C in air) reaction conditions. Moreover, the hydrophobic functionalization rendered the catalysts reusable without showing significant activity loss. The decreased activity after successive catalytic runs was attributed to a low level of Pd-leaching and a gradual collapse of mesopores of host silica. The cross-coupling protocol with the designed catalysts would be practical for use as an economical synthetic method for the construction of biphenyl derivatives. the Partner Organisations 2014.
- Huang, Shao-Hsien,Liu, Chun-Hsia,Yang, Chia-Min
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- Structure-Modified Germatranes for Pd-Catalyzed Biaryl Synthesis
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Germanium, a member of 14th group that falls between Si and Sn, has remained considerably ignored as a nucleophile for a long time. Compared with other forms of Ge-containing nucleophiles, germatranes are structure-defined, easily accessible, and stabilized nucleophilic fragments, but they fail to meet the need of high reactivity and facile introducing to organics. Herein, we report a modified structure of germatranes, whose cross-coupling reactivity is greatly improved. The structure can be easily constructed from inexpensive industrial GeO2, and corresponding Ge-Cl and Ge-H can also be obtained after facile transformations. Moreover, Ar-Ge can be effectively synthesized either from Grignard reagents or Pd-catalyzed germylation of aryl halides.
- Song, Hai-Jie,Jiang, Wei-Tao,Zhou, Qiao-Lan,Xu, Meng-Yu,Xiao, Bin
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- Bis(imino)acenaphthene (BIAN)-supported palladium(ii) carbene complexes as effective C-C coupling catalysts and solvent effects in organic and aqueous media
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The synthesis and catalytic properties of two new 1,2-acenaphthenyl N-heterocyclic carbene-supported palladium(ii) catalysts are presented. The acenaphthenyl carbene has been prepared with mesityl or 1,5-diisopropyl N-aryl substituents. Comprehensive catalytic studies for the Suzuki coupling of aryl halides with aryl boronic acids have been conducted. In general, the diisopropyl-functionalised catalyst showed superior selectivity and reactivity. A comparison of the catalytic performances in dichloromethane, toluene and water at low temperatures (30-40 °C) is also presented. Both catalysts were proficient in the homogeneous Suzuki coupling of aryl iodides, bromides and chlorides with boronic acids in dichloromethane. Similar reactions in water led to the formation of insoluble colloidal catalytic species that still exhibited high activity in the Suzuki reaction with aryl chlorides. Reactions performed in toluene showed intermediate results; partial catalyst decomposition led to concomitant homogeneous and heterogeneous catalysis. The heterogeneous palladium precipitates could be easily recovered by filtration and reactivated for subsequent use. Activation energies determined for aryl bromide-based Suzuki reactions were found to be in the range of 159-171 kJ mol-1 in organic solvents and 111-116 kJ mol-1 in water. The corresponding activation energy for the aryl chloride was found to be 322 kJ mol-1 in water. the Partner Organisations 2014.
- Crawford, Katherine A.,Cowley, Alan H.,Humphrey, Simon M.
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- Interplay between n→π? Interactions and Dynamic Covalent Bonds: Quantification and Modulation by Solvent Effects
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Orbital donor-acceptor interactions play critical roles throughout chemistry, and hence, their regulation and functionalization are of great significance. Herein we demonstrate for the first time the investigation of n→π? interactions through the strategy of dynamic covalent chemistry (DCC), and we further showcase its use in the stabilization of imine. The n→π? interaction between donor X and acceptor aldehyde/imine within 2-X-2′-formylbiphenyl derivatives was found to significantly influence the thermodynamics of imine exchange. The orbital interaction was then quantified through imine exchange, the equilibrium of which was successfully correlated with the difference in natural bond orbital stabilization energy of n→π? interactions of aldehyde and its imine. Moreover, the examination of solvent effects provided insights into the distinct feature of the modulation of n→π? interaction with aprotic and protic solvents. The n→π? interaction involving imine was enhanced in protic solvents due to hydrogen bonding with the solvent. This finding further enabled the stabilization of imine in purely aqueous solution. The strategies and results reported should find application in many fields, including molecular recognition, biological labeling, and asymmetric catalysis.
- Zheng, Hao,Ye, Hebo,Yu, Xiaoxia,You, Lei
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- Ruthenium complex catalyzed direct ortho arylation and alkenylation of aromatic imines with organic halides
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Matrix presented The ortho position of the aromatic ring of imino group substituted aromatic compounds is directly arylated and alkenylated with organic halides in the presence of a catalytic amount of a ruthenium(II)-phosphine complex.
- Oi, Shuichi,Ogino, Yukako,Fukita, Susumu,Inoue, Yoshio
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- Highly efficient suzuki cross-coupling catalyzed by palladium/phosphine- imidazolium carbene system
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Novel phosphine-imidazolium salts 2 have been synthesized and successfully used in palladium-catalyzed Suzuki cross-coupling. A combination of 0.05 mol % of [Pd(η-C3H5)Cl]2 and 0.1 mol % of 2b in the presence of 2 equivs. of K3PO4 as base provided coupling products in excellent yields in the reaction of aryl bromides and chlorides with aryl boronic acids.
- Wang, Ai-E.,Zhong, Jun,Xie, Jian-Hua,Li, Kai,Zhou, Qi-Lin
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- A highly active and recyclable catalyst: Phosphine dendrimer-stabilized nickel nanoparticles for the Suzuki coupling reaction
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We report here the first dendritic phosphine-stabilized nickel nanoparticles, which can be prepared from nickel(II) chloride, a third generation phosphine dendrimer and the surfactant tetraoctylammonium bromide (TOABr) by two-phase reduction using sodium borohydride. The resulting nickel nanoparticles are found to be a highly active and recyclable catalyst for Suzuki coupling reactions, especially those extended to aryl chloride substrates, affording the biaryls in moderate to good yields. Copyright
- Wu, Lei,Ling, Jie,Wu, Zong-Quan
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- An improved Suzuki–Miyaura cross-coupling reaction with the aid of in situ generated PdNPs: evidence for enhancing effect with biphasic system
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We present here an improved Suzuki–Miyaura cross-coupling in WERSA (Water Extract of Rice Straw Ash). We found that, although the reaction can be run in neat water, use of alcoholic co-solvent dramatically enhances the yield and generates in situ PdNPs during the reaction. The PdNPs were characterized by TEM and powder XRD analysis. The rice straw ash was characterized by EDX, Flame photometry, and Ion-Exchange chromatography to reveal a broad range of active metal species. The chemical analysis reports of ash showed the presence of oxides of K, Na, and Ca, which probably in the presence of water produces the corresponding hydroxides responsible for the basicity.
- Mahanta, Abhijit,Mondal, Manoj,Thakur, Ashim Jyoti,Bora, Utpal
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- Modular Arene Difunctionalization of Unactivated C-O and C-H Bonds by Sequential Chromium-Catalyzed Transformations
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Sequential transformations of unactivated C-O and C-H bonds under chromium catalysis are described. The use of a N-benzyl-substituted imino group as an auxiliary combined with chromium(II) chloride as a precatalyst and 2,3-dichlorobutane as an oxidant allows the arene C-O and C-H bonds to sequentially couple to arylmagnesium reagents to incorporate two identical or different aryl groups into the ortho positions of benzaldehydes.
- Rong, Zhi,Luo, Meiming,Zeng, Xiaoming
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- Low-Valent, High-Spin Chromium-Catalyzed Cleavage of Aromatic Carbon-Nitrogen Bonds at Room Temperature: A Combined Experimental and Theoretical Study
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The cleavage of aromatic carbon-nitrogen bonds catalyzed by transition metals is of high synthetic interest because such bonds are common in organic chemistry. However, few metal catalysts can be used to selectively break C(aryl)-N bonds in electronically neutral molecules. We report here the first low-valent, high-spin chromium-catalyzed cleavage of C(aryl)-N bonds in electronically neutral aniline derivatives at room temperature. By using simple and inexpensive chromium(II) chloride as precatalyst, accompanied by an imino auxiliary, the selective arylative and alkylative C-C coupling of C(aryl)-N bonds can be achieved. Crossover experiments indicate that a low-valent chromium species, formed in situ by reduction of CrCl2 with Grignard reagent, is responsible for the catalytic cleavage of C(aryl)-N bonds. DFT calculations show that facile insertion of the C(aryl)-N bond by chromium(0) can take place in a high-spin quintet (S = 2) ground state, whereas the lower-spin singlet (S = 0) and triplet (S = 1) states are inaccessible in energy. It was found that both donation of the sole paired d electrons in the d6 shell of high-spin chromium(0) to the antibonding orbital of the C(aryl)-N bond and the nitrogen ligating interaction to the metal center with its lone pair play important roles in the cleavage of the C(aryl)-N bond by the zerovalent chromium species.
- Cong, Xuefeng,Fan, Fei,Ma, Pengchen,Luo, Meiming,Chen, Hui,Zeng, Xiaoming
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- N-Heterocyclic carbene silver(I), palladium(II) and mercury(II) complexes: Synthesis, structural studies and catalytic activity
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The bis-benzimidazolium salts, 1,2-bis[2-(N-R-benzimidazolemethyl)phenoxy] ethane chloride (L1H2: R = Et, L2H2: R = nBu), 1,3-bis[2-(N-R-benzimidazolemethyl)phenoxy]propane chloride (L3H2: R = nPr, L4H 2: R = nBu) and bis[N-R-benzimidazolemethyl]mesitylene 2X (L5H2: R = nBu, X = I; L6H 2: R = PyCH2, X = Br and L7H2: R = PhCH2, X = Br), as well as their eight NHC silver(i), palladium(ii) and mercury(ii) complexes, [(L1Ag)2Ag2Cl 4] (1), [L1(PdCl2CH3CN)2] (2), [(L2Ag)2AgCl2][AgCl2] (3), [(L3Ag2Cl2)n] (4), [(L 4Ag2Cl2)n] (5), [L 5HgI][HgI4]0.5 (6), [L6Hg][HgBr 4] (7) and [L7Ag][(NO3)0.76Br 0.24] (8) have been prepared and characterized. The complexes 1-8 adopt four different structures: (1) with bis-macrometallocycles connected via a Ag2Cl4 unit for 1 and via a AgCl2 unit for 3, (2) an open structure formed via one ligand and two metal atoms for 2, (3) 1D polymeric chains formed by the monomers of a cage-like cavity via weak Ag...Cl bonds (monomer: L3Ag2Cl2 for 4 and L4Ag2Cl2 for 5) and (4) a macrocyclic structure formed by one ligand and one metal for 6-8. In the crystal packing of these complexes, 1D supramolecular chains, 2D supramolecular layers and 3D supramolecular architectures are formed via intermolecular weak interactions, including π-π interactions, hydrogen bonds, C-H...π contacts and weak Hg...Br bonds. Particularly, the catalytic activity of the NHC palladium(ii) complex 2 in Suzuki-Miyaura cross-coupling reactions was studied.
- Liu, Qing-Xiang,Wang, Hong,Zhao, Xiao-Jun,Yao, Zhao-Quan,Wang, Zhi-Qiang,Chen, Ai-Hui,Wang, Xiu-Guang
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- Photochemical oxidation of phenanthrene sorbed on silica gel
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There have been relatively few detailed studies of PAH photochemical degradation mechanisms and products at solid/air interfaces under controlled conditions. Results from mechanistic studies on particulate simulants are important in understanding the fates of PAH sorbed on similar materials in natural settings. In this study, the photolysis of phenanthrene (PH) on silica gel, in the presence of air, has been carefully examined. Once sorbed onto the silica surface, PH is not observed to repartition into the gas phase, even under vacuum, and dark reactions of PH are not observed at the silica/air interface. Photolysis (254 nm) of PH leads to the formation of 2,2'-biformylbiphenyl (1), 9,10-phenanthrenequinone (2), cis-9,10-dihydrodihydroxyphenanthrene (3), benzocoumarin (4), 2,2'-biphenyldicarboxylic acid (5), 2-formyl-2'-biphenylcarboxylic acid (5), 2-formylbiphenyl (7),1,2-naphthalenedicarboxylic acid (8), and phthalic acid (9). These products account for 85-90% of the reacted PH. The photoproducts are independent of excitation wavelength (254 and 350 nm), and the reaction proceeds entirely through an initial step involving the addition of singlet molecular oxygen to the ground state of phenanthrene with subsequent thermal and/or photochemical reactions of the initially formed product. Singlet molecular oxygen is produced through quenching of the lowest triplet state of PH at the silica gel/air interface. The high material balance and detailed mechanistic information provided by this study serve as a standard for comparisons with the products and mechanism of PH photochemical oxidation on environmentally derived inorganic oxide particulates.
- Barbas, John T.,Sigman, Michael E.,Dabestani, Reza
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- Pd immobilized in mesoporous silica particles as recyclable catalysts for suzuki-miyaura coupling: Cooperative effects exerted by co-immobilized amine functionalities
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A bifunctional heterogeneous palladium catalyst bearing additional basic sites was successfully prepared by sequential Cu-catalyzed 1,3-dipolar alkyne-azide cycloaddition and thermal nitroxide-exchange reaction of surface-bound alkoxyamines. This catalyst shows high activity in the Suzuki-Miyaura cross-coupling. The additional basic functionality acts cooperatively since an analogous heterogeneous Pd catalyst lacking the amine functionality is less active. Such catalysts can be recycled up to ten times without loss of activity. Georg Thieme Verlag Stuttgart. New York.
- Dickschat, Arne T.,Surmiak, Sabrina,Studer, Armido
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- Palladium Supported on Silk Fibroin for Suzuki–Miyaura Cross-Coupling Reactions
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Silk fibroin supported Pd (Pd/SF) has been prepared and used as catalyst in Suzuki–Miyaura cross-coupling reactions in water/ethanol (4:1 v/v) mixture. The reactions proceed rapidly with aryl iodides and boronic acids with different electronic properties using low metal loading (0.38 mol-%). Pd/SF exhibits better recyclability compared to other biopolymer-supported Pd catalysts, up to nineteen cycles without loss of activity.
- Albano, Gianluigi,Farinola, Gianluca M.,Lo Presti, Marco,Milella, Antonella,Omenetto, Fiorenzo G.,Rizzo, Giorgio
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- Phosphine free diamino-diol based palladium catalysts and their application in Suzuki-Miyaura cross-coupling reactions
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Inexpensive air and moisture stable diamino-diol ligands [(2-OH-C10H6)CH2(μ-NC4H8N)CH2(C10H6-2-OH)] (1) and [(5-tBuC6H3-2-OH)CH2(μ-NC4H8N)CH2(5-tBuC6H3-2-OH)] (2) were synthesized by reacting corresponding alcohols with formaldehyde and piperazine. Treatment of ligands 1 and 2 with Pd(OAc)2 in 1:1 molar ratio afforded neutral palladium complexes [Pd{(OC10H6)CH2(μ-NC4H8N)CH2(C10H6O)}] (3) and [Pd{(5-tBuC6H3-2-O)CH2(μ-NC4H8N)CH2(5-tBuC6H3-2-O)}] (4) in good yield. The palladium complexes 3 and 4 are employed in Suzuki-Miyaura cross-coupling reactions between phenylboronic acid and several aryl chlorides or bromides. They are found to be competent homogeneous catalysts for a variety of substrates to afford the coupled products in good to excellent yields. The crystal structures of compounds 2 and 4 are also reported.
- Mohanty, Sasmita,Suresh,Balakrishna, Maravanji S.,Mague, Joel T.
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- Catalytic Cleavage of Unactivated C(aryl)-P Bonds by Chromium
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We describe here the coupling to transform aryl phosphine derivatives by the cleavage of unactivated C(aryl)-P bonds with chromium catalysis, allowing us to achieve the reaction with alkyl bromides and arylmagnesium reagents under mild conditions. Mechani
- Ling, Liang,Luo, Meiming,Tang, Jinghua,Yuan, Shuqing,Zeng, Xiaoming
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supporting information
p. 1581 - 1586
(2022/03/14)
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- Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones
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We have developed a cerium-photocatalyzed aerobic oxidation of primary and secondary benzylic alcohols to aldehydes and ketones using inexpensive CeCl3 7H2O as photocatalyst and air oxygen as the terminal oxidant.
- K?nig, Burkhard,Kumar, Sumit,Stahl, Jessica,Yatham, Veera Reddy,Yedase, Girish Suresh
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supporting information
p. 1727 - 1732
(2021/08/05)
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- Transient imine as a directing group for the metal-free o-C-H borylation of benzaldehydes
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Organoboron reagents are important synthetic intermediates and have wide applications in synthetic organic chemistry. The selective borylation strategies that are currently in use largely rely on the use of transition-metal catalysts. Hence, identifying much milder conditions for transition-metal-free borylation would be highly desirable. We herein present a unified strategy for the selective C-H borylation of electron-deficient benzaldehyde derivatives using a simple metal-free approach, utilizing an imine transient directing group. The strategy covers a wide spectrum of reactions and (i) even highly sterically hindered C-H bonds can be borylated smoothly, (ii) despite the presence of other potential directing groups, the reaction selectively occurs at the o-C-H bond of the benzaldehyde moiety, and (iii) natural products appended to benzaldehyde derivatives can also give the appropriate borylated products. Moreover, the efficacy of the protocol was confirmed by the fact that the reaction proceeds even in the presence of a series of external impurities.
- Rej, Supriya,Chatani, Naoto
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p. 2920 - 2929
(2021/03/01)
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- Synthesis of highly substituted fluorenones via metal-free TBHP-promoted oxidative cyclization of 2-(aminomethyl)biphenyls. Application to the total synthesis of nobilone
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Highly substituted fluorenones are readily prepared in mostly fair to good yields via metal- and additive-free TBHP-promoted cross-dehydrogenative coupling (CDC) of readily accessible N-methyl-2-(aminomethyl)biphenyls and 2-(aminomethyl)biphenyls. This methodology is compatible with numerous functional groups (methoxy, cyano, nitro, chloro, and SEM and TBS-protective groups for phenols) and was further utilized in the first total synthesis of the natural product nobilone.
- Bracher, Franz,Jourjine, Ilya A. P.,Krau?, Jürgen,Zeisel, Lukas
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p. 2668 - 2679
(2021/11/30)
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- Anchored PdCl2 on fish scale: an efficient and recyclable catalyst for Suzuki coupling reaction in aqueous media
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PdCl2 anchored on fish scale (FS) complex were intended to a heterogeneous catalyst for ligand-free Suzuki coupling reaction in aqueous media. The catalyst FS-PdCl2 was characterized by FT-IR, powder XRD, XPS and SEM. FS-PdCl2 complex has been successfully implemented for Suzuki coupling reactions of various halogenated aromatics with arylboronic acid to provide the corresponding biaryl compounds under environmentally friendly conditions (40 °C, water solvent). Moreover, the efficient catalyst shows excellent stability and recyclability, and its catalytic activity without any decrease after 8 times consecutive reused.
- Yang, Quanlu,Yang, Fawang,Zhang, Ying,Hou, Juanjuan,Li, Jiankun,Cheng, Jinkui,Wu, Shang,Zhan, Huiying,Zhang, Xinghui,Shi, Haixiong
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supporting information
(2020/12/25)
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- Fe3O4-SAHPG-Pd0 nanoparticles: A ligand-free and low Pd loading quasiheterogeneous catalyst active for mild Suzuki–Miyaura coupling and C-H activation of pyrimidine cores
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This paper reports a green magnetic quasiheterogeneous efficient palladium catalyst in which Pd0 nanoparticles have been immobilized in self-assembled hyperbranched polyglycidole (SAHPG)-coated magnetic Fe3O4 nanoparticles (Fe3O4-SAHPG-Pd0). This catalyst has been used for effective ligandless Pd catalyzed Suzuki–Miyaura coupling reactions of different aryl halides with substituted boronic acids at room temperature and in aqueous media. Herein, SAHPG is used as support; it also acts as a reducing agent and stabilizer to promote the transformation of PdII to Pd0 nanoparticles. Also, this environmental friendly quasiheterogeneous catalyst is employed for the first time in the synthesis of new pyrimido[4,5-b]indoles via oxidative addition/C-H activation reactions on the pyrimidine rings, which were obtained with higher yield and faster than when Pd(OAc)2 was used as the catalyst. Interestingly, the above-mentioned catalyst could be recovered in a facile manner from the reaction mixture by applying an external magnet device and recycled several times with no significant decrease in the catalytic activity.
- Azizollahi, Hamid,Eshghi, Hossein,García-López, José-Antonio
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- Magnetic covalently immobilized nickel complex: A new and efficient method for the Suzuki cross-coupling reaction
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In this study, an efficient procedure was reported to prepare Fe3O4@SiO2 magnetic nanoparticles (MNPs) with immobilized nickel NPs. In order to increase the activity of this catalyst, creatine as a ligand with high content of nitrogen atoms was linked onto the magnetic core–shell structure. Then, Ni(II) ions were coordinated on the surface of the silica-coated MNPs and reduced to Ni(0) NPs to obtain the final catalyst. The catalytic activity of the prepared catalyst was studied for the synthesis of biaryl derivatives via the Suzuki–Miyaura cross-coupling reaction in high yields. The catalyst could also be recovered and reused with no loss of activity over five successful runs.
- Keyhaniyan, Mahdi,Khojastehnezhad, Amir,Eshghi, Hossein,Shiri, Ali
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- Silica-coated magnetic nanoparticles functionalized cobalt complex: a recyclable and efficient catalyst for the C?C bond formation
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In this study, the Co-based catalyst was prepared by cobalt immobilization on the surface of functionalized silica-coated magnetic NPs (Fe3O4@SiO2-CT-Co) as a magnetically core–shell nanocatalyst and characterized by FT-IR, TGA, XRD, VSM, SEM, TEM, EDX, EDX mapping, and ICP techniques and appraised in the Suzuki–Miyaura cross-coupling reaction under mild reaction conditions. The results displayed the superparamagnetic behavior of the Fe3O4 NPs core encapsulated by SiO2 shell, and the size of the particles was estimated about 30?nm. Compared with the previously reported catalysts, the engineered Fe3O4@SiO2-CT-Co catalyst provided perfect catalytic performance for the Suzuki–Miyaura cross-coupling reaction in water as a green solvent and it was much cheaper in the comparison with the traditional Pd-based catalysts. Importantly, the durability of magnetic nanocatalyst was studied and observed that it is stable under the reaction conditions and could be easily reused for at least six successive cycles without any significant decrease in its catalytic activity. Graphic abstract: [Figure not available: see fulltext.]
- Haqjow, Hanif,Raoufi, Farveh
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p. 4113 - 4128
(2021/07/26)
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- Synthesis of N-Heterocyclic Carbine Silver(I) and Palladium(II) Complexes with Acylated Piperazine Linker and Catalytic Activity in Three Types of C—C Coupling Reactions
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Two bis-imidazolium salts LH2·Cl2 and LH2·(PF6)2 with acylated piperazine linker and two N-heterocyclic carbene (NHC) silver(I) and palladium(II) complexes [L2Ag2](PF6)2 (1) and [L2Pd2Cl4] (2) were prepared. The crystal structures of LH2·Cl2 and 1 were confirmed by X-ray analysis. In 1, one 26-membered macrometallocycle was generated through two silver(I) ions and two bidentate ligands L. The catalytic activity of 2 was investigated in Sonogashira, Heck-Mizoroki and Suzuki-Miyaura reactions. The results displayed that these C—C coupling reactions can be smoothly carried out under the catalysis of 2.
- Liu, Qingxiang,Zhang, Xiantao,Zhao, Zhixiang,Li, Xinying,Zhang, Wei
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supporting information
p. 605 - 613
(2021/02/01)
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- Potent Inhibition of Nicotinamide N-Methyltransferase by Alkene-Linked Bisubstrate Mimics Bearing Electron Deficient Aromatics
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Nicotinamide N-methyltransferase (NNMT) methylates nicotinamide (vitamin B3) to generate 1-methylnicotinamide (MNA). NNMT overexpression has been linked to a variety of diseases, most prominently human cancers, indicating its potential as a therapeutic target. The development of small-molecule NNMT inhibitors has gained interest in recent years, with the most potent inhibitors sharing structural features based on elements of the nicotinamide substrate and the S-adenosyl-l-methionine (SAM) cofactor. We here report the development of new bisubstrate inhibitors that include electron-deficient aromatic groups to mimic the nicotinamide moiety. In addition, a trans-alkene linker was found to be optimal for connecting the substrate and cofactor mimics in these inhibitors. The most potent NNMT inhibitor identified exhibits an IC50 value of 3.7 nM, placing it among the most active NNMT inhibitors reported to date. Complementary analytical techniques, modeling studies, and cell-based assays provide insights into the binding mode, affinity, and selectivity of these inhibitors.
- Buijs, Ned,Campagna, Roberto,Emanuelli, Monica,Gao, Yongzhi,Gutiérrez-De-Terán, Hugo,Innocenti, Paolo,Jespers, Willem,Martin, Nathaniel I.,Parsons, Richard B.,Sartini, Davide,Van Haren, Matthijs J.,Van Westen, Gerard J. P.,Zhang, Yurui
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p. 12938 - 12963
(2021/09/11)
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- Gold Catalysts Can Generate Nitrone Intermediates from a Nitrosoarene/Alkene Mixture, Enabling Two Distinct Catalytic Reactions: A Nitroso-Activated Cycloheptatriene/Benzylidene Rearrangement
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Gold-catalyzed reactions of cycloheptatrienes with nitrosoarenes yield nitrone derivatives efficiently. This reaction sequence enables us to develop gold-catalyzed aerobic oxidations of cycloheptatrienes to afford benzaldehyde derivatives using CuCl and nitrosoarenes as co-catalysts (10-30 mol %). Our density functional theory calculations support a novel nitroso-activated rearrangement, tropylium → benzylidene. With the same nitrosoarenes, we developed their gold-catalyzed [2 + 2 + 1]-annulations between nitrosobenzene and two enol ethers to yield 5-alkoxyisoxazolidines using 1,4-cyclohexadienes as hydrogen donors.
- Cheng, Mu-Jeng,Kardile, Rahul Dadabhau,Kuo, Tung-Chun,Liu, Rai-Shung,More, Sayaji Arjun
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p. 5506 - 5511
(2021/07/31)
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- Reductive Cross-Coupling between Unactivated C(aryl)-N and C(aryl)-O Bonds by Chromium Catalysis Using a Bipyridyl Ligand
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Reductive cross-coupling between two chemically inert bonds remains a great challenge in synthetic chemistry. We report here the reductive cross-coupling between unactivated C(aryl)-N and C(aryl)-O bonds that was achieved by chromium catalysis. The simple and inexpensive CrCl2 salt, combined with important bipyridyl ligand and magnesium reductant, shows high reactivity in the successive cleavage of C(aryl)-N bonds of aniline derivatives and C(aryl)-O bonds of aryl esters, allowing the cross-coupling of these two unactivated and different bonds to occur in a reductive fashion to form a C(aryl)-C(aryl) bond. Mechanistic studies by deuterium-labeling experiments indicate that the C(aryl)-N bonds in anilines are preferentially cleaved by reactive Cr species, in which the ligation of bipyridyl with Cr by adopting a coordination model in 1:1 ratio can be considered.
- Cong, Xuefeng,Fan, Fei,Luo, Meiming,Tang, Jinghua,Zeng, Xiaoming,Zhao, Lixing
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supporting information
p. 12834 - 12840
(2020/08/21)
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- Immobilized Pd on Eggshell Membrane: A powerful and recyclable catalyst for Suzuki and Heck cross-coupling reactions in water
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A stable heterogeneous palladium catalysts, the waste eggshell membrane (ESM) anchored Pd complex, was synthesized by a simple and green technique. The catalyst obtained can display an outstanding catalytic activity for Suzuki and Heck coupling reactions in water media. The reactions of various aryl halides with aryl boronic acids and terminal alkenes provided the corresponding products in moderate to excellent yields. More importantly, this novel and efficient catalyst with high stability can be easily reused for at least twelve times with no decrease of the catalytic activity, performing an endurable and wide tolerance of the substrates. Facile synthesis, high catalytic activity, and recyclability make these catalysts interesting for further studies.
- Wu, Shang,Jiang, Hongyan,Zhang, Hong,Zhao, Lianbiao,Yuan, Peilin,Zhang, Ying,Su, Qiong,Wang, Yanbin,Wu, Lan,Yang, Quanlu
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- Chemoselective Cross-Coupling between Two Different and Unactivated C(aryl)-O Bonds Enabled by Chromium Catalysis
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We report here the first example of cross-coupling between two different and unactivated C(aryl)-O bonds with chromium catalysis. The combination of a low-cost Cr(II) salt, 4,4′-di-tert-butyl-2,2′-dipyridyl (dtbpy) as the ligand, and magnesium as the reductant shows high reactivity in promoting the reductive cross-coupling of aryl methyl ether derivatives with aryl esters by cleavage and coupling of two different C(aryl)-O bonds under mild conditions. The formation of active low-valent Cr species by reduction of CrCl2 with Mg can be considered, which prefers to initially activate the C(aryl)-O bond of phenyl methyl ether with the chelation help of dtbpy and an o-imine auxiliary. The subsequent consecutive reduction, second C(aryl)-O activation, and reductive elimination allow for the achievement of selective cross-coupling of C(aryl)-O/C(aryl)-O bonds.
- Tang, Jinghua,Liu, Liu Leo,Yang, Shangru,Cong, Xuefeng,Luo, Meiming,Zeng, Xiaoming
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p. 7715 - 7720
(2020/05/20)
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- Immobilized N-Heterocyclic Carbene-Palladium(II) Complex on Graphene Oxide as Efficient and Recyclable Catalyst for Suzuki–Miyaura Cross-Coupling and Reduction of Nitroarenes
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Abstract: A new and efficient N-heterocyclic carbene (NHC)-palladium(II) complex immobilized on graphene oxide (NHC-Pd@GO) has been successfully designed and synthesized. The prepared NHC-Pd@GO heterogeneous catalyst was fully characterized using a combination of fourier transform infrared spectroscopy (FTIR), inductively coupled plasma-optical emission spectroscopy (ICP-OES), energy-dispersive X-ray spectroscopy (EDS), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller surface area analysis (BET). This new air- and moisture-stable NHC-Pd@GO heterogeneous catalytic system was found to be a highly active catalyst in the Suzuki–Miyaura cross-coupling between phenylboronic acid and various aryl halides (bromides/chlorides/iodides) and in the reduction of nitroarenes. These organic transformations were best performed in an aqueous ethanol and aqueous methanol solvent system respectively with low catalyst loading under mild reaction conditions. Furthermore, NHC-Pd@GO heterogeneous catalyst could be recovered easily and reused at least eleven times in Suzuki–Miyaura cross-coupling and nine times in reduction of nitroarenes without any considerable loss of its catalytic activity. The stability and good selectivity of the NHC-Pd@GO heterogeneous catalyst in recycling experiments signify that it could be useful for practical application in various organic transformations. Graphic Abstract: [Figure not available: see fulltext.].
- Kandathil, Vishal,Kulkarni, Bhakti,Siddiqa, Aisha,Kempasiddaiah, Manjunatha,Sasidhar,Patil, Shivaputra A.,Patil, Siddappa A.
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p. 384 - 403
(2020/01/06)
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- Synthesis of water soluble Pd-Piperidoimidazolin-2-ylidene complexes and their catalytic activities in neat water
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Through the strategy of water soluble N-heterocyclic carbene (NHC) ligand, Pd-catalyzed reactions were developed in aqueous media. Therefore, four new piperidoimidazolinium salts (1a-d) consisting of sulfonate (a), esther (b, c) and carboxylic acid (d) functionalities and their water-soluble Pd-NHC complexes (2a-d) were synthesized. The new compounds were characterized by elemental analysis, FTIR, TGA, UV–vis and NMR spectroscopy. The catalytic activities of water soluble Pd-NHC complexes (2a-d) were investigated using the Suzuki-Miyaura (S-M) reaction and the reduction of nitroarenes. We found that the water-soluble polar or ionic groups on piperidoimidazolin-2-ylidine had an effect on the catalytic activity. The water-soluble catalyst can be recycled efficiently and reused six times with only a very slight loss of catalytic activity.
- ?ak?r, Sinem,Türkmen, Hayati
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- Palladium-catalyzed external-CO-free reductive carbonylation of aryl sulfonates
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Pd-catalyzed reductive carbonylation of aryl sulfonates using N-formylsaccharin as a carbon monoxide (CO) surrogate was developed. This external-CO-free carbonylation provides a safe and practical access to aldehydes from phenol derivatives. The reaction has a broad substrate scope, rendering it an attractive method for synthesizing aldehydes.
- Konishi, Hideyuki,Kumon, Minoru,Yamaguchi, Miyuki,Manabe, Kei
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- Switchable Bifunctional Bistate Reusable ZnO-Cu for Selective Oxidation and Reduction Reaction
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Herein we disclosed the utilization of copper loaded zinc oxide (ZnO-Cu) for its stimuli (O2/light) responsive switchable performance between its reduced (S-1) and oxidized (S-2) state for two antagonistic reactions, namely oxidation of alkyl arenes/heteroarenes to aldehydes/ketones and reduction of nitro arenes/heteroarenes to corresponding amines. The two states of the catalyst showed its switchable performance as highly active and poorly active catalyst for oxidation and reduction, and both reactions could be turned "off" and "on" by changing the stimuli (light and O2/N2). The switching efficiency between the states and their relative reactivity were found to be consistent under variety of reaction conditions and remain unaltered irrespective of oxidation-reduction (or vice versa) sequence and substrates used in the reaction. The photo catalysts (S-1 and S-2) demonstrated good catalytic activity, multiple reusability, broad substrate scope, and reasonable functional group tolerance for both the reactions and probed its quality performance in a large-scale setup. The system was used in an assisted tandem catalysis setup for the synthesis of benzyl amines utilizing both oxidation and reduction reaction by stimuli responsive switching between the states of the catalyst.
- Sarmah, Kasturi,Mukhopadhyay, Subhamoy,Maji, Tarun K.,Pratihar, Sanjay
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p. 732 - 745
(2019/01/11)
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- 6-Arylphenanthridines from Aryl o-Biaryl Ketones with 1,1,1,3,3,3-Hexamethyldisilazane and Molecular Iodine
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Warming treatment of aryl o-biaryl ketones with 1,1,1,3,3,3-hexamethyldisilazane in the presence of Sc(OTf)3 in toluene, followed by the reaction with molecular iodine and K2CO3 in a mixture of THF and methanol at 60 °C gave the corresponding 6-arylphenanthridines in good to moderate yields. The present reaction is a one-pot method for the preparation of 6-arylphenanthridines from aryl o-biaryl ketones through the cyclization of imino-nitrogen-centered radicals that were generated from N-iodo aryl o-biaryl ketimines formed from the reaction of aryl biaryl ketimines with molecular iodine.
- Kobayashi, Eiji,Kishi, Atsushi,Togo, Hideo
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p. 7335 - 7347
(2019/11/22)
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- An efficient Pd(II)-(2-aminonicotinaldehyde) complex as complementary catalyst for the Suzuki-Miyaura coupling in water
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An efficient new Pd(II)-(2-aminonicotinaldehyde)-catalyzed Suzuki-Miyaura coupling of the aryl halides (Br, Cl and I) and organoboronic acids at moderate temperature in water is described. Low catalyst loading, easy accessibility, being an air-stable catalyst, functional group compatibility, and water as the reaction medium are some of the key features of this synthetic method. This protocol is also applicable for gram scale.
- Thunga, Sanjeeva,Poshala, Soumya,Anugu, Naveenkumar,Konakanchi, Ramaiah,Vanaparthi, Satheesh,Kokatla, Hari Prasad
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supporting information
p. 2046 - 2048
(2019/07/04)
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- Involving Single-Atom Silver(0) in Selective Dehalogenation by AgF under Visible-Light Irradiation
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The dehalogenation-arylation and the hydrodehalogenation of various types of organic halides are selectively realized using AgF and visible light without any organic additives under mild conditions. Single-atom silver(0) (denoted as SAAg) serves as the catalytically active center, and the TOF of SAAg reaches 6000 h-1. This elusive activity of Ag is beyond that expected from its ionic, nano, or bulk forms.
- Wu, Wenli,Cui, Enxin,Zhang, Yun,Zhang, Chen,Zhu, Feng,Tung, Chen-Ho,Wang, Yifeng
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p. 6335 - 6341
(2019/07/04)
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- FIBROBLAST GROWTH FACTOR 23 ANTAGONISTS AND RELATED COMPOSITIONS AND METHODS
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This disclosure relates to small molecule inhibitors of Fibroblast growth factor 23 (FGF-23) and related compositions and methods of treatment.
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Page/Page column 25-26; 36
(2019/05/15)
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- Ruthenium(0)-Catalyzed Cross-Coupling of Anilines with Organoboranes by Selective Carbon-Nitrogen Cleavage
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Selective activation of neutral carbon-nitrogen bonds is of great synthetic importance, because amines are among the most prevalent motifs across organic and bioactive molecules. Herein, we report the Ru(0)-catalyzed selective cleavage of neutral C(aryl)-N bonds in generic aniline derivatives enabled by a combination of Ru3(CO)12 and an imino auxiliary. These mild conditions provide a direct route to high-value biaryl ketones and biaryl aldehydes after facile in situ hydrolysis. A broad range of organoboranes and anilines can be coupled with high C-N cleavage selectivity. Most crucially, the reaction achieves exquisite selectivity for activation of C(aryl)-N bonds in the presence of typically more kinetically favorable C(aryl)-H bonds. The method provides a strategy for the construction of functionalized terphenyls by exploiting orthogonal properties of the Ru(0) catalyst system and traceless nucleophilic properties of anilines.
- Zhao, Qun,Zhang, Jin,Szostak, Michal
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p. 8171 - 8177
(2019/08/22)
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- Carbocation catalysed ring closing aldehyde-olefin metathesis
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A highly efficient aldehyde-olefin metathesis catalysed by the carbocation, 4-phenylphenyl-diphenylmethylium ion, has been developed. This protocol is characterized by high yields, low catalyst loading (down to 2 mol%), good functional group compatibility and mild reaction conditions.
- Ni, Shengjun,Franzén, Johan
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supporting information
p. 12982 - 12985
(2018/11/23)
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- Palladium-Catalyzed Reductive Conversion of Acyl Fluorides via Ligand-Controlled Decarbonylation
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Ligand-controlled non-decarbonylative and decarbonylative conversions of acyl fluorides were developed using a Pd(OAc)2/Et3SiH combination. When tricyclohexylphosphine (PCy3) was used as the ligand, aldehydes were obtained as simple reductive conversion products. The use of 1,2-bis(dicyclohexylphosphino)ethane (Cy2P(CH2)2PCy2, DCPE) as the ligand, however, favored the formation of hydrocarbons, which are decarbonylative reduction products.
- Ogiwara, Yohei,Sakurai, Yuka,Hattori, Hiroyuki,Sakai, Norio
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supporting information
p. 4204 - 4208
(2018/07/29)
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- Chemoselective Reduction of Sterically Demanding N,N-Diisopropylamides to Aldehydes
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A sequential one-pot process for chemoselectively reducing sterically demanding N,N-diisopropylamides to aldehydes has been developed. In this reaction, amides are activated with EtOTf to form imidates, which are reduced with LiAlH(OR)3 [R = t-Bu, Et] to give aldehydes by hydrolysis of the resulting hemiaminals. The non-nucleophilic base 2,6-DTBMP remarkably improves reaction efficiency. The combination of EtOTf/2,6-DTBMP and LiAlH(O-t-Bu)3 was found to be optimal for reducing alkyl, alkenyl, alkynyl, and 2-monosubstituted aryl N,N-diisopropylamides. In contrast, EtOTf and LiAlH(OEt)3 in the absence of base were found to be optimal for reducing extremely sterically demanding 2,6-disubstituted N,N-diisopropylbenzamides. The reaction tolerates various reducible functional groups, including aldehyde and ketone. 1H NMR studies confirmed the formation of imidates stable in water. The synthetic usefulness of this methodology was demonstrated with N,N-diisopropylamide-directed ortho-metalation and C-H bond activation.
- Xiao, Peihong,Tang, Zhixing,Wang, Kai,Chen, Hua,Guo, Qianyou,Chu, Yang,Gao, Lu,Song, Zhenlei
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p. 1687 - 1700
(2018/02/23)
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- Bench-Stable Sulfoxide-Based Boronates: Preparation and Application in a Tandem Suzuki Reaction
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A set of novel aromatic and heteroaromatic bench-stable sulfoxide-based boronates was prepared. The structure of the boronates was established by means of X-ray crystallography, and the prepared boronates were successively used in Suzuki cross-coupling reactions under different conditions. We also developed a tandem Suzuki reaction so that a base is generated during the nucleophilic addition of Grignard reagents to 4-bromobenzaldehyde. The formed intermediates were smoothly coupled with the prepared boronates and the boronic acids under external base-free conditions. (Figure presented.).
- ?ubiňák, Marek,Eigner, Václav,Tobrman, Tomá?
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p. 4604 - 4614
(2018/10/31)
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- Green Synthesis of Palladium Nanoparticles: Applications in Aryl Halide Cyanation and Hiyama Cross-Coupling Reaction Under Ligand Free Conditions
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Abstract: In the current work, palladium nanoparticles (Pd NPs) were prepared from palladium acetate biogenically using the aqueous-ethanolic extract of black pepper (Piper nigrum) and characterized by various analytical techniques like XRD, FE-SEM, EDS, TEM, ATR-IR, UV–Vis spectroscopy, BET, TGA and ICP-OES analysis. The reduction of Pd(II)?to?Pd(0) is achieved by the action of various phytochemicals present in the black pepper extract like phenols, acids, pellitorine, ethyl piperonyl cyanoacetate, piperine and N-isobutyl-tetradeca-2,4-dienamide. The biosynthesized Pd NPs shown excellent catalytic activity in aryl halide cyanation and Hiyama cross-coupling reactions. Also, less toxic potassium hexacyanoferrate(II) trihydrate was used as cyanide source in aryl halide cyanation and Hiyama cross-coupling was performed under fluoride free condition. Both reactions proceeded well with Pd NPs under ligand free circumstances to give good to excellent yields. The Pd NPs were recovered after each reaction and recycled up to five times in aryl halide cyanation and ten times in Hiyama cross-coupling without considerable loss in the activity. Graphical Abstract: Green synthesis of palladium nanoparticles: applications in aryl halide cyanation and Hiyama cross-coupling reaction under ligand free conditions. [Figure not available: see fulltext.].
- Kandathil, Vishal,Dateer, Ramesh B.,Sasidhar,Patil, Shivaputra A.,Patil, Siddappa A.
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p. 1562 - 1578
(2018/04/02)
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- Synthesis, characterization and first application of covalently immobilized nickel-porphyrin on graphene oxide for Suzuki cross-coupling reaction
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In this study, nickel(ii)-coordinated 5,10,15,20-tetrakis(aminophenyl)porphyrin (NiTAPP) as a macrocyclic complex was covalently grafted to the edge of graphene oxide (GO). The prepared nanocatalyst was well characterized by various techniques such as FT-IR, Raman, XRD, TEM, SEM, EDX, TGA, ICP-OES, UV and XPS. All analyses confirmed the successful immobilization of NiTAPP on GO. The synthesized catalyst was applied to evaluate its performance in the Suzuki-Miyaura cross-coupling reaction. GO/NiTAPP exhibited good catalytic efficiency with a high yield of products. Moreover, the suggested catalyst could be recycled for five consecutive cycles without a noticeable decrease in its catalytic activity or metal leaching.
- Keyhaniyan, Mahdi,Shiri, Ali,Eshghi, Hossein,Khojastehnezhad, Amir
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p. 19433 - 19441
(2018/12/13)
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- Suzuki–Miyaura coupling reaction in water in the presence of robust palladium immobilized on modified magnetic Fe3O4 nanoparticles as a recoverable catalyst
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Aryl halides and especially inactive aryl chlorides were coupled to benzenoid aromatic rings in a Suzuki–Miyaura coupling reaction in the absence of organic solvents and toxic phosphine ligands. The reaction was catalysed by a recoverable magnetic nanocatalyst, Pd@Fe3O4, in aqueous media. This method is green, and the catalyst is easily removed from the reaction media using an external magnetic field and can be re-used at least 10 times without any considerable loss in its activity. The catalyst was characterized using scanning and transmission electron microscopies, thermogravimetric analysis, inductively coupled plasma spectroscopy, Fourier transform infrared spectroscopy, CHN analysis, X-ray diffraction and vibrating sample magnetometry.
- Dadras, Arefeh,Naimi-Jamal, M. Reza,Moghaddam, Firouz Matloubi,Ayati, Seyed Ebrahim
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- Palladium complexes with two unsymmetrical Schiff base ligands: Highly active catalyst for activation of chloroarenes in Suzuki-Miyaura reaction
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Two new unsymmetrical Schiff base derived palladium(II) complexes, [PdCl2{bis(salicylidene)-2-aminobenzamide}] (C1) and [PdCl2{N,N'-bis(salicylidene)-2-aminobenzylamine}] (C2) have been synthesized and characterized. The complexes have been explored as catalysts for the Suzuki-Miyaura cross-coupling reactions of aryl halides with arylboronic acids. An optimization study reveals that under similar experimental conditions, the complex C1 shows superior activity over the complex C2. Using the complex C1 as catalyst, less reactive chloroarenes are efficiently converted to their corresponding biaryls under relatively mild conditions (80oC, 0.5 mol% catalyst) using EtOH as an environmentally safer reaction media. Excellent yields of cross coupling products are also obtained with aryl bromides at room temperature in neat water with low catalyst loading (0.02 mol %).
- Puzari, Amlan,Shahnaz, Nasifa,Das, Pankaj
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p. 837 - 842
(2020/06/26)
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- Facile synthesis of indene and fluorene derivatives through AlCl3-catalyzed cyclization of in situ formed iminium ions
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A simple AlCl3-catalyzed condensation/cyclization cascade process between aldehydes and sulfonamide is reported, in which two new bonds and one five-membered ring are simultaneously formed with water as the byproduct. This method provides a rapid access to indenamine and 9-aminofluorene derivatives. Additionally, these products can be transformed into corresponding indanones and fluorenones under the developed conditions.
- Chen, Lei,Teng, Wei,Geng, Xin-Le,Zhu, Yi-Fan,Guan, Yong-Hong,Fan, Xiaohui
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- Sulfur-Directed Ligand-Free C-H Borylation by Iridium Catalysis
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An iridium-catalyzed ortho C-H borylation reaction directed by cyclic dithioacetal moiety is disclosed. A series of borylation products were obtained in moderate to good yields under mild conditions in exclusive mono- and ortho-regioselectivity. Thus, the 1,3-dithiane or 1,3-dithiolane group serves as a remarkable effective directing group for C-H borylation without any ligand assistance. The further transformations of the borylation products are also carried out to change boryl group to other functional groups.
- Liu, Li,Wang, Guanghui,Jiao, Jiao,Li, Pengfei
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supporting information
p. 6132 - 6135
(2017/11/24)
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- Intramolecular Acylation of Unactivated Pyridines or Arenes via Multiple C-H Functionalizations: Synthesis of All Four Azafluorenones and Fluorenones
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An unprecedented intramolecular acylation of unactivated pyridines via multiple C(sp3/sp2)-H functionalizations of a methyl, hydroxymethyl, or aldehyde group has been developed providing a general access to all four azafluorenones. The application of this protocol is further demonstrated to the synthesis of azafluorenone related fused nitrogen heterocycles and fluorenones. In addition, design and synthesis of a novel fluorene based organic emitter for potential use in organic light emitting devices (OLEDs) is also reported.
- Laha, Joydev K.,Jethava, Krupal P.,Patel, Sagarkumar,Patel, Ketul V.
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- Palladium nanoparticles in cross-linked polyaniline as highly efficient catalysts for Suzuki-Miyaura reactions
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Palladium nanoparticles supported on cross-linked polyaniline with bulky phosphorus ligands were developed. These catalysts showed high efficiency in the Suzuki-Miyaura reaction of aryl chlorides and bromides with phenylboronic acids. Aryl chlorides and bromides with functional groups, such as CN, MeO, CHO, MeCO and NO2, were converted to the corresponding biphenyls in high yields with catalyst loading. Additionally, the catalysts combined high activity with good reusability; they could be used at least five times for the Suzuki-Miyaura coupling reaction.
- Fan, Haipeng,Qi, Zhengliang,Sui, Dejun,Mao, Fei,Chen, Rizhi,Huang, Jun
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p. 589 - 596
(2017/04/04)
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- An N-Heterocyclic Carbene-Nickel Half-Sandwich Complex as a Precatalyst for Suzuki-Miyaura Coupling of Aryl/Heteroaryl Halides with Aryl/Heteroarylboronic Acids
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A nickel half-sandwich complex supported by our original NHC ligand was developed as a robust precatalyst for Suzuki-Miyaura cross-coupling. The addition of PPh3 was a crucial element in the suppression of side reactions and in accelerating the cross-coupling reaction. By employing the optimal conditions, aryl-aryl, heteroaryl-aryl, and heteroaryl-heteroaryl couplings were achieved.
- Ando, Shin,Matsunaga, Hirofumi,Ishizuka, Tadao
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p. 1266 - 1272
(2018/06/18)
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- Palladium-Catalyzed Arylation of Arylboronic Acids with Yagupolskii-Umemoto Reagents
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A Pd-catalyzed Suzuki cross-coupling of arylboronic acids with Yagupolskii-Umemoto reagents was explored. In contrary to trifluoromethylations, the Pd-catalyzed reaction of R-B(OH)2 and [Ar2SCF3]+[OTf]- provided the arylation products (R-Ar) in good to high yields. The reaction confirms that the S-Ar bonds of [Ar2SCF3]+[OTf]- can be readily cleaved in the presence of Pd complexes. The relatively electron-poor aryl groups of asymmetric [Ar1Ar2SCF3]+[OTf]- salts are more favorably transferred compared to the electron-rich ones. This reaction represents the first report of utilization of [Ar2SCF3]+[OTf]- as arylation reagents in organic synthesis.
- Wang, Shi-Meng,Wang, Xiao-Yan,Qin, Hua-Li,Zhang, Cheng-Pan
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p. 6542 - 6546
(2016/05/02)
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- Pd-PEPPSI Complexes bearing bulky [(1,2-Di-(tert-butyl)acenaphthyl] (DtBu-An) on N-heterocarbene backbones: Highly efficient for suzuki-miyaura cross-coupling under aerobic conditions
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With the goal of achieving highly efficient palladium-catalyzed cross-coupling reactions under mild reaction conditions, the Pd-PEPPSI complexes C1 and C2 bearing 1,2-di(tert-butyl)acenaphthyl (DtBu-An) backbones were synthesized and characterized, and their use in Suzuki-Miyaura cross-coupling was investigated. The effects of catalyst structure and reaction conditions on the cross-coupling efficiency were evaluated in detail. The significant differences in catalytic activity compared with classical PEPPSI-IPr and PEPPSI-IPrAn precatalysts are discussed, where the axial sterics on the backbone play an important role. At low palladium loadings of 0.05-0.1 mol % and upon the addition of the relatively weak base K3PO4, the palladium complex C1 was found to be highly efficient for the coupling of (hetero)aryl chlorides with arylboronic acids under aerobic conditions, affording the corresponding biaryls in excellent yields.
- Lan, Xiao-Bing,Chen, Fu-Min,Ma, Bei-Bei,Shen, Dong-Sheng,Liu, Feng-Shou
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p. 3852 - 3860
(2016/12/07)
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- One-Pot Synthesis of Polysubstituted Spirofluorene-Indene via Ru(II)-Catalyzed [3 + 2] Annulation and Intramolecular Friedel-Crafts Cyclization
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Ru(II)-catalyzed one-pot synthesis of polysubstituted spirofluorene-indenes via [3 + 2] annulation and then intramolecular Friedel-Crafts alkylation has been achieved. The simple method provides a broad scope of aryl ketones and internal alkynes, achieving PAHs skeletons in moderate to good yields.
- Zhu, Yu-Qin,Dong, Lin
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p. 9973 - 9979
(2015/11/03)
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- Regio- and Chemoselective Kumada-Tamao-Corriu Reaction of Aryl Alkyl Ethers Catalyzed by Chromium under Mild Conditions
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Acting as an environmentally benign synthetic tool, the cross-coupling reactions with aryl ethers via C-O bond activation have attracted broad interest. However, the functionalizations of C-O bonds are mainly limited to nickel catalysis, and selectivity has long been a prominent challenge when several C-O bonds are present in the one molecule. We report here the first chromium-catalyzed selective cross-coupling reactions of aryl ethers with Grignard reagents by the cleavage of C-O(alkyl) bonds. Diverse transformations were achieved using simple, inexpensive chromium(II) precatalyst combining imino auxiliary at room temperature. It offers a new avenue for buildup functionalized aromatic aldehydes with high efficiency and selectivity.
- Cong, Xuefeng,Tang, Huarong,Zeng, Xiaoming
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supporting information
p. 14367 - 14372
(2015/12/01)
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