- Bimetallic Ni/Cu mesoporous silica nanoparticles as an efficient and reusable catalyst for the Sonogashira cross-coupling reactions
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A bimetallic mesoporous system (Ni/Cu-MCM-41) has been developed and evaluated as an efficient catalyst for the Sonogashira cross-coupling reaction, under palladium-free conditions. In this new methodology, a wide range of aryl halides react with phenylacetylene to give the corresponding disubstituted alkynes in good yields. Moreover, the present catalytic system is desired because of its high efficiency, easy preparation, low cost, high activity, and good recyclability.
- Nasresfahani, Zahra,Kassaee, Mohamad Z.
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supporting information
(2021/02/12)
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- Metal-Free and syn-Selective Hydrohalogenation of Alkynes through a Pseudo-Intramolecular Process
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A new metal-free hydrohalogenation method for alkynes has been developed, which proceeds through a pseudo-intramolecular process. In this reaction, ethynylaniline serves as a substrate to quantitatively form an anilinium salt upon treatment with hydrochloric acid. The spatial proximity facilitates the efficient electrophilic addition of HCl to the ethynyl group in syn-mode, affording the corresponding chloroalkene without overaddition. This protocol was applied to HBr and HI, and the corresponding bromo- and iodoalkenes were obtained, respectively. The obtained chloroalkene was converted to tri-substituted alkenes possessing different aryl/alkynyl groups through Pd-catalyzed cross-coupling reactions.
- Asahara, Haruyasu,Mukaijo, Yusuke,Muragishi, Kengo,Iwai, Kento,Ito, Akitaka,Nishiwaki, Nagatoshi
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p. 5747 - 5755
(2021/10/20)
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- One-Pot Generation of Benzynes from Phenols: Formation of Primary Anilines by the Deoxyamination of Phenols
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Benzynes were selectively generated in situ from phenols and trapped regioselectively with potassium hexamethyldisilazide to form primary anilines following acidic workup. The direct conversion of a phenolic hydroxyl group into a free amino group is a useful method for the preparation of primary aryl amines that are hard to synthesize by using coupling reactions involving phenol derivatives with ammonia. Whereas reactions of ortho- and meta-substituted phenols produced meta-substituted anilines exclusively, those of para-substituted phenols provided ortho-silylanilines.
- Akai, Shuji,Ikawa, Takashi,Masuda, Shigeaki
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- A Co-Cu bimetallic magnetic nanocatalyst with synergistic and bifunctional performance for the base-free Suzuki, Sonogashira, and C-N cross-coupling reactions in water
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A novel magnetically recyclable bimetallic catalyst was prepared by anchoring imidazolium moiety and PEG chains on Fe3O4 NPs and named as Fe3O4?PEG/Cu-Co. It was found to be a powerful catalyst for the Sonogashira, Suzuki, and C-N cross-coupling reactions in water as a green solvent without the need for any external base. Fe3O4?PEG/Cu-Co was well characterized with FT-IR, FE-SEM, TEM, VSM, EDX, ICP, UV-visible, CV, and XPS analyses. Optimum ranges of parameters such as time, temperature, and amount of catalyst were investigated by Design-Expert 10.0.7 software for C-C Suzuki, Sonogashira, and C-N cross-coupling reactions to find the optimum conditions. The catalyst was compatible with a variety of aryl halides and N-arenes and gave favorable coupling products with good to high yields for all of them. Hot filtration and Hg poisoning tests involving the nanocatalyst revealed the stability, low metal leaching, and heterogeneous nature of the catalyst. Reaction mechanisms were proposed by study of the UV-visible spectra in situ as well as hydroquinone tests during the progress of reactions. In situ XPS analysis was also used to study the reaction mechanism. To prove the synergistic performance of Co and Cu in the catalyst, its various homologues were synthesized and applied to a model reaction separately, and then their catalytic activities were investigated. Finally, the catalyst could be recovered from the reaction mixture simply, and reused for several cycles with a minimum loss in catalytic activity and performance.
- Allahresani, Ali,Kazemnejadi, Milad,Nasseri, Mohammad Ali,Rezazadeh, Zinat
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p. 10645 - 10660
(2020/09/18)
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- Green synthesis of graphene oxide (GO)-anchored Pd/Cu bimetallic nanoparticles using: Ocimum sanctum as bio-reductant: An efficient heterogeneous catalyst for the Sonogashira cross-coupling reaction
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To explore the synergism between two metal centers we have synthesized graphene oxide (GO) supported Pd/Cu?GO, Pd?GO and Cu?GO nanoparticles through bio-reduction of Pd(NO3)2 and CuSO4·5H2O using Tulsi (Ocimum sanctum) leaf extract as the reducing and stabilizing agent. The graphene oxide (GO) was obtained by oxidation of graphite following a simplified Hummer's method. The as-prepared nanomaterials have been extensively characterized by FTIR, powder X-ray diffraction (PXRD), HRTEM, TEM-EDS, XPS, ICP-AES and BET surface area measurement techniques. The morphological study of Pd/Cu?GO revealed that crystalline bimetallic alloy type particles were dispersed on the GO layer. The activity of Pd?GO, Cu?GO and Pd/Cu?GO as catalysts for the Sonogashira cross-coupling reaction have been investigated and it was found that the Pd/Cu?GO nanostructure showed highly superior catalytic activity over its monometallic counterparts, substantiating the cooperative influence of the two metals. The inter-atom Pd/Cu transmetalation between surfaces was thought to be responsible for its synergistic activity. The catalyst showed higher selectivity towards coupling of aryl iodides with both aliphatic and aryl alkynes resulting in moderate to excellent isolated yield of the desired products (45-99%). The products have been characterized by GC-MS and 1H-NMR spectroscopic techniques and compared with authentic samples. The Pd/Cu?GO catalyst could be easily isolated from the reaction products and reused for up to at least ten successive runs effectively.
- Borah, Geetika,Gogoi, Pradip K.,Hussain, Farhaz Liaquat,Mech, Swapna Devi,Pahari, Pallab,Sultana, Samim
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p. 23108 - 23120
(2020/07/03)
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- Sustainable Ligand-Free Heterogeneous Palladium-Catalyzed Sonogashira Cross-Coupling Reaction in Deep Eutectic Solvents
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The commercially available and cheap Pd/C was found to promote Sonogashira couplings in the environmentally friendly choline chloride/glycerol eutectic mixture in the absence of external ligands. Under heterogeneous conditions, (hetero)aryl iodides were successfully coupled with both aromatic and aliphatic alkynes in yields ranging from 50 to 99 % within 3 h at 60 °C. The aforementioned catalytic system proved to be effective also towards electron-rich iodides, which are notoriously known to be poorly reactive in Pd-catalyzed Sonogashira coupling reactions. The eutectic mixture and the catalyst could easily and successfully be recycled up to four times with an E-factor as low as 24.4.
- Messa, Francesco,Dilauro, Giuseppe,Perna, Filippo M.,Vitale, Paola,Capriati, Vito,Salomone, Antonio
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p. 1979 - 1984
(2020/02/20)
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- Magnetic Cu–Schiff base complex with an ionic tail as a recyclable bifunctional catalyst for base/Pd-free Sonogashira coupling reaction
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Abstract: A Cu(II)–Schiff base complex containing imidazolium ionic phase was prepared and decorated on γ-Fe2O3 magnetic nanoparticles (γ-Fe2O3@Cu(II)IL-SB) and found to be an efficient catalyst for the Pd- and base-free Sonogashira coupling reaction. The heterogeneous catalyst was characterized by FTIR spectroscopy, UV–visible spectroscopy, FE-SEM, TEM, XRD spectroscopy, EDX spectroscopy, VSM, ICP spectroscopy, and atomic absorption spectroscopy. The coupling reactions were performed using the catalyst under mild and base-free conditions, and high-to-excellent yields were obtained for a variety of substrates. The catalyst demonstrates a dual-functionality arising from metal sites and imidazolium moieties and that the later plays a base role. Reusability and stability of γ-Fe2O3@Cu(II)IL-SB were studied several times, which can be reused up to eight consecutive runs with at least reduction in catalytic activity. Also, the mechanism of this bifunctional catalytic system was thoroughly investigated. Graphic abstract: A new and efficient method has been developed for the base- and Pd-free Sonogashira cross-coupling reactions of aryl halides with phenyl acetylene using a bifunctional γ-Fe2O3@Cu(II)IL-SB catalyst with imidazolium moiety under mild conditions[Figure not available: see fulltext.].
- Nasseri, Mohammad Ali,Rezazadeh, Zinat,Kazemnejadi, Milad,Allahresani, Ali
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p. 2693 - 2705
(2019/07/23)
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- The CuFe2O4@SiO2@ZrO2/SO42-/Cu nanoparticles: An efficient magnetically recyclable multifunctional Lewis/Br?nsted acid nanocatalyst for the ligand- and Pd-free Sonogashira cross-coupling reaction in water
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Herein, the synthesis and application of copper-incorporated sulfated zirconium oxide supported on CuFe2O4 NPs (CuFe2O4@SiO2@ZrO2/SO42-/Cu NPs) as a novel Lewis/Br?nsted acid nanocatalyst were studied for the Sonogashira C-C cross-coupling reaction. The fabricated CuFe2O4@SiO2@ZrO2/SO42-/Cu catalyst exhibited efficient activity for a large variety of aryl iodides/bromides and, most importantly, aryl chlorides in water and in the presence of NaOH as a base in short reaction times. The catalyst was fully characterized by FTIR, TG-DTG, VSM, XRD, EDX, FE-SEM and TEM analyses. A synergetic effect could be considered to have arisen from the various Lewis acid and Br?nsted acid sites present in the catalyst. The efficient incorporation of copper into zirconia provided a robust highly stable hybrid, which prevented any metal leaching, whether from the magnetite moiety and/or Cu sites in the reaction mixture. Moreover, the catalyst was successfully recovered from the mixture by a simple external magnet and reused for at least 9 consecutive runs. Zero metal leaching, stability, consistency with a variety of substrates, fast performance, cost-effectiveness, environmental friendliness, and preparation with accessible and cheap materials are some of the advantages and highlights of the current protocol.
- Nasseri, Mohammad Ali,Alavi, Seyyedeh Ameneh,Kazemnejadi, Milad,Allahresani, Ali
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p. 20749 - 20759
(2019/07/12)
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- Silver-Mediated Trifluoromethoxylation of (Hetero)aryldiazonium Tetrafluoroborates
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Here we report a silver-mediated trifluoromethoxylation of (hetero)aryldiazonium tetrafluoroborates by converting an aromatic amino group into an OCF3 group. This method, which can be considered to be a trifluoromethoxylation variation of the classic Sandmeyer-type reaction, uses readily available aryl and heteroaromatic amines as starting materials and AgOCF3 as trifluoromethoxylating reagents. The broad substrate scope and simple, mild reaction condition made this transformation a valuable method in constructing aryl-OCF3 bonds.
- Yang, Yu-Ming,Yao, Jian-Fei,Yan, Wei,Luo, Zhuangzhu,Tang, Zhen-Yu
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supporting information
p. 8003 - 8007
(2019/10/11)
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- Catalytic Activation of Trimethylsilylacetylenes: A One-Pot Route to Unsymmetrical Acetylenes and Heterocycles
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For the synthesis of unsymmetrical acetylenes, a Sonogashira coupling-deprotection-Sonogashira coupling reaction sequence is often used. Removal of protecting groups requires harsh conditions or an excess of difficult to handle and expensive reagents. Herein, we disclose a novel catalytic method for the selective deprotection of trimethylsilylacetylenes in Sonogashira reaction. The reagent hexafluorosilicic acid, an inexpensive nontoxic compound, was used to promote the selective desilylation. This method enables the efficient synthesis of unsymmetric acetylenes with other silylated functional groups present. Further possibilities of the method were explored by synthesis of heterocycles.
- Lasányi, Dániel,Mészáros, ádám,Novák, Zoltán,Tolnai, Gergely L.
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p. 8281 - 8291
(2018/06/11)
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- AMINATION AND HYDROXYLATION OF ARYLMETAL COMPOUNDS
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In one aspect, the present disclosure provides methods of preparing a primary or secondary amine and hydroxylated aromatic compounds. In some embodiments, the aromatic compound may be unsubstituted, substituted, or contain one or more heteroatoms within the rings of the aromatic compound. The methods described herein may be carried out without the need for transition metal catalysts or harsh reaction conditions.
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Paragraph 0098; 0134; 0135; 0195
(2018/03/25)
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- Rapid heteroatom transfer to arylmetals utilizing multifunctional reagent scaffolds
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Arylmetals are highly valuable carbon nucleophiles that are readily and inexpensively prepared from aryl halides or arenes and widely used on both laboratory and industrial scales to react directly with a wide range of electrophiles. Although C-C bond formation has been a staple of organic synthesis, the direct transfer of primary amino (-NH2) and hydroxyl (-OH) groups to arylmetals in a scalable and environmentally friendly fashion remains a formidable synthetic challenge because of the absence of suitable heteroatom-transfer reagents. Here, we demonstrate the use of bench-stable N-H and N-alkyl oxaziridines derived from readily available terpenoid scaffolds as efficient multifunctional reagents for the direct primary amination and hydroxylation of structurally diverse aryl- and heteroarylmetals. This practical and scalable method provides one-step synthetic access to primary anilines and phenols at low temperature and avoids the use of transition-metal catalysts, ligands and additives, nitrogen-protecting groups, excess reagents and harsh workup conditions.
- Gao, Hongyin,Zhou, Zhe,Kwon, Doo-Hyun,Coombs, James,Jones, Steven,Behnke, Nicole Erin,Ess, Daniel H.,Kürti, László
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p. 681 - 688
(2017/06/30)
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- Ligand- and copper-free Sonogashira and Heck couplings of (Het)aryl chlorides and bromides catalyzed by palladium nanoparticles supported on in situ generated Al(OH)3
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The ligand- and copper-free Sonogashira reaction of (Het)aryl halides (Br and Cl) with various terminal alkynes and the Heck coupling of (Het)aryl halides (Br and Cl) with a series of olefins, catalyzed by palladium nanoparticles supported on newly generated Al(OH)3, were developed. The catalyst can be readily recovered and reused 6 times without significant loss of activity and palladium leaching.
- Li, Xing,Gong, Xiaolei,Li, Zhipeng,Chang, Honghong,Gao, Wenchao,Wei, Wenlong
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p. 2475 - 2479
(2017/02/05)
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- Highly modulated bisindoles: ligands for copper-catalyzed Sonogashira reaction
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Bisindoles (BIMs) were modulated as powerful N,N′ donor ligands for the copper-catalyzed Sonogashira reaction. Ligand screening experiments on 11 BIM compounds found that 3,3′-(4-chlorophenyl)methylenebis(1-methyl-1H-indole) (10%) efficiently accelerated CuCl (5%)-catalyzed cross-coupling of aryl iodides with terminal alkynes. A wide range of substituted aryl iodides and/or alkyl- and aryl-substituted terminal alkynes were examined, leading to the corresponding coupling products with yields up to 99%. An efficient and scalable protocol for the synthesis of BIM ligands on a gram scale, with extremely low catalyst loading of o-ClC6H4NH3 +Cl?, was also developed with a reaction time of 20?min with yields up to 93%. This novel N,N′ ligand was air-stable, easily available and highly modulated with low copper loading. Copyright
- Wang, Xiu,Wang, Zhenhua,Wu, Ya,Luo, Yanlong,Zhang, Guofang,Jian, Yajun,Sun, Huaming,Zhang, Weiqiang,Gao, Ziwei
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p. 831 - 834
(2016/09/20)
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- Method for catalyzing Sonogashira coupling reaction by synergetic catalysis of 1,2,3-triazole monosubstituted1,3,5-triazine
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The invention discloses a method for catalyzing Sonogashira coupling reaction by synergetic catalysis of 1,2,3-triazole monosubstituted1,3,5-triazine. According to the method, CuSO4.5H2O which has good stability and is cheap and easily available and a tri
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Paragraph 0017; 0034; 0035
(2017/01/17)
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- Fabrication of PEI grafted Fe3O4/SiO2/P(GMA-co-EGDMA) nanoparticle anchored palladium nanocatalyst and its application in Sonogashira cross-coupling reactions
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Novel magnetic Fe3O4/SiO2/P(GMA-co-EGDMA) composite nanoparticles grafted with hyperbranched/linear polyethylenimine ligands were fabricated. Subsequently, nano palladium was effectively anchored on this carrier through complexation between Pd2+ ions and multifunctional organic ligands, then a novel supported Pd nanoparticle catalyst with good dispersion and high loading of Pd nanoparticles was successfully prepared after the following reduction process. Afterwards, the as-prepared supported Pd nanoparticle catalyst was characterized by SEM, TEM, XRD, FTIR, TG and ICP-AES. Ultimately, the catalytic performance of the supported Pd nanoparticle catalyst was investigated by catalysing the Sonogashira cross-coupling reaction between aryl halides and arylacetylene. Research shows that the novel supported Pd nanoparticle catalyst exhibits very superior catalytic activity in catalysing the Sonogashira cross-coupling reaction between aryl halides and arylacetylene, even in the absence of the cocatalyst (CuI), and the side reaction producing the by-product (1,3-diyne) can be inhibited effectively. In addition, this supported Pd nanoparticle catalyst exhibits stable recovery and high catalytic activity, for it can be effectively reused 8 times without obvious loss of catalytic activity. Furthermore, the yields of the target products of the Sonogashira cross-coupling reaction between iodobenzene and phenylacetylene, 3-aminophenylacetylene and 4-(ethynyl)phthalic anhydride can reach approximately 79%, 78% and 95% after this novel supported Pd nanoparticle catalyst has been used eight times, respectively.
- Li, Wei,Jia, Xiangkun,Zhang, Baoliang,Tian, Lei,Li, Xiangjie,Zhang, Hepeng,Zhang, Qiuyu
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p. 2925 - 2934
(2015/04/22)
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- Chemoselective synthesis of unsymmetrical internal alkynes or vinyl sulfones via palladium-catalyzed cross-coupling reaction of sodium sulfinates with alkynes
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A highly efficient and mild palladium-catalyzed cross-coupling of sodium sulfinates and alkynes for the selective synthesis of unsymmetrical internal alkynes and vinyl sulfones has been developed. This methodology has advantages of easily accessible starting materials, functional group tolerance and a wide range of substrates, which provides rapid access to alkynes and vinyl sulfones.
- Xu, Yanli,Zhao, Jinwu,Tang, Xiaodong,Wu, Wanqing,Jiang, Huanfeng
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p. 2029 - 2039
(2014/07/07)
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- Ligand-free copper-catalyzed cross-coupling reaction of alkynes with aryl iodides and vinyl halides
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A copper-catalyzed cross-coupling reaction of alkynes with aryl iodides is described. The system tolerates a broad range of functional groups and enables the sterically demanding substrates presented during the catalysis with only 5-10 mol% of Cu2O as the catalyst. Georg Thieme Verlag Stuttgart. New York.
- Tsai, Wan-Ting,Lin, Yun-Yung,Chen, Yi-An,Lee, Chin-Fa
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supporting information
p. 443 - 447
(2014/03/21)
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- Practical synthesis of unsymmetrical diarylacetylenes from propiolic acid and two different aryl bromides
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A palladium catalyst that mediates the one-pot sequential Sonogashira and decarboxylative coupling of propiolic acid with two different aryl bromides has been developed. Selective coupling of the first aryl bromide was achieved in the presence of a copper-free, monometallic catalyst generated in situ from allylpalladium chloride dimer and SPhos with tetra-n-butylammonium fluoride as the base in an N-methyl-2-pyrrolidone/water solvent mixture. Upon addition of another aryl bromide and raising the temperature from 50 to 80°C, the intermediate arylpropiolic acid underwent decarboxylative coupling to give the corresponding diarylacetylene. Thus, the new system permits a one-pot three-component synthesis of unsymmetrical diarylacetylenes from widely available aryl bromides, rather than expensive aryl iodides, and propiolic acid, rather than (trimethylsilyl)acetylene, as an inexpensive and easy-to-handle acetylene synthon. The process is highly selective, modular, and gives access to a wide range of unsymmetrical diarylacetylenes in good yields. A palladium-catalyzed three component synthesis of diaryl acetylenes has been optimized. Several disubstituted alkynes have been prepared from two different arylbromides and propiolic acid in good yields. Copyright
- Tartaggia, Stefano,De Lucchi, Ottorino,Goossen, Lukas J.
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supporting information; experimental part
p. 1431 - 1438
(2012/04/04)
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- Microwave-assisted copper-catalyzed cross-coupling reaction of alkynes with aryl iodides and vinyl halides
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The microwave-assisted, copper-catalyzed coupling of terminal alkynes with aryl iodides and vinyl halides is reported. In general, the reactions are completed in 10-30 min using 2-5 mol% [CuI(xantphos)] as a catalyst to provide the corresponding alkynes and enynes in good to excellent yields. A broad spectrum of aryl iodides, vinyl iodides, and bromides are coupled with aryl- and alkyl alkynes.
- Tsai, Wen-Ting,Lin, Yun-Yung,Wang, Yu-Jen,Lee, Chin-Fa
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supporting information; experimental part
p. 1507 - 1510
(2012/06/18)
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- Synthesis and characterization of recyclable and recoverable MMT-clay exchanged ammonium tagged carbapalladacycle catalyst for Mizoroki-Heck and Sonogashira reactions in ionic liquid media
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An efficient synthesis of an ammonium tagged carbapalladacycle 5, in modest yield, has been achieved. Further, the clay-nanocomposite 6 was prepared by ion exchange of 5 into clay interlayers as a new organic-inorganic hybrid catalytic system. The ionic t
- Singh, Vasundhara,Ratti, Rajni,Kaur, Sukhbir
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scheme or table
p. 13 - 19
(2011/03/17)
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- Copper-catalyzed decarboxylative cross-coupling of alkynyl carboxylic acids with aryl halides
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The copper-catalyzed decarboxylative reactions of alkynyl carboxylic acids with aryl halides were performed under relatively mild reaction conditions. Benzofurans could be further prepared smoothly by a one-pot domino protocol on the basis of decarboxylative cross-coupling of 2-iodophenol.
- Zhao, Dongbing,Gao, Chao,Su, Xiaoyu,He, Yunqing,You, Jingsong,Xue, Ying
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supporting information; experimental part
p. 9049 - 9051
(2011/02/17)
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- Efficient copper-catalyzed cross-coupling reaction of alkynes with aryl iodides
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A copper-catalyzed cross-coupling reaction of alkynes with aryl iodides is described. The system, tolerates a broad range of functional groups and enables the use of sterically demanding substrates with only 1.0-2.5 mol-% of Cu 2O and 1.0-2.5 mol-% of xantphos as the catalyst.
- Lin, Che-Hung,Wang, Yu-Jen,Lee, Chin-Fa
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supporting information; experimental part
p. 4368 - 4371
(2010/09/20)
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- Compounds for the treatment of inflammatory disorders and microbial diseases
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This invention relates to compounds of the Formulae (I)-(IX): or a pharmaceutically acceptable salt, solvate, ester or isomer thereof, which can be useful for the treatment of diseases or conditions mediated by MMPs, aggrecanase, ADMP, LpxC, ADAMs, TACE,
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Page/Page column 46
(2008/06/13)
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- Sonogashira coupling with aqueous ammonia directed to the synthesis of azotolane derivatives
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Sonogashira coupling with aqueous ammonia is tolerable for the reaction of aryl iodides or terminal alkynes bearing an azobenzene group. The reaction of (4-heptyloxyphenyl)ethyne with (4-heptyloxyphenyl)-(4-iodophenyl)diazene in the presence of 1 mol% of
- Mohamed Ahmed, Mohamed S.,Mori, Atsunori
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p. 9977 - 9982
(2007/10/03)
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- Photolysis of regioisomeric diazides of 1,2-diphenylacetylenes studies by matrix-isolation spectroscopy and DFT calculations.
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A series of diazides of 1,2-diphenylacetylenes was photolyzed in matrices at low temperature and transient photoproducts were characterized by using IR, UV/vis methods combined with ESR studies. Theoretical calculations were also used to understand the experimental findings. The introduction of phenylethynyl groups on phenyl azides has little effect on the photochemical pathway. Thus, upon photoexcitation, (phenylethynyl)phenyl azides afforded the corresponding triplet nitrene, which is in photoequilibrium with the corresponding azacycloheptatetraene. In marked contrast, azidophenylethynyl groups exhibited a dramatic effect not only on the photochemical pathway of phenyl azides but also on the electronic and molecular structure of the photoproducts. The patterns of the effect depended upon the relative position of azide groups in the diphenylacetylene unit. Whenever two azide groups were situated in a conjugating position with respect to each other, as in p,p'-, o,o'-, and p,o'-bis(azides), the azides always resulted in the formation of a quinoidal diimine diradical in which unpaired electrons were extensively delocalizedin the pi-conjugation. The situation changed rather dramatically when azide groups were introduced in the meta position. Thus, the formation of azacycloheptatetraene was noted in the photolysis of the m.m'-isomer. ESR studies indicated the generation of a quintet state that was shown to be a thermally populated state with a very small energy gap of ca. 100 cal mol(-1). The m,p'-isomer was shown to be an excellent precursor for the high-spin quintet dinitrene.The IR spectra of the photoproduct showed no bands ascribable to azacycloheptatetraene. The observed spectra were in good agreement with that calculated for the quintet state. Strong EPR signals assignable to the quintet state were observed, along with rather weak signals due to mononitrenes. Moreover, the quintet bis(nitrene) was rather photostable under these conditions.
- Tomioka, Hideo,Sawai, Shinji
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p. 4441 - 4450
(2007/10/03)
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- Molecular construction based on icosahedral carboranes and aromatic N,N′-dimethylurea groups. Aromatic layered molecules and a transition metal complex
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cis-Preference of N-methyl aromatic ureas in combination with regulation of the C-substituent on an o-carborane cage is applicable to construct structurally unique macromolecules. Aromatic ureas with multilayer structure (5-12) and an aromatic urea containing an intramolecular nido-carborane-cobalt complex (13) were synthesized and their structures were determined by X-ray crystallography.
- Endo, Yasuyuki,Songkram, Chalermkiat,Yamasaki, Ryu,Tanatani, Aya,Kagechika, Hiroyuki,Takaishi, Kojiro,Yamaguchi, Kentaro
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- Phenylacetylene-substituted schiff's base momomers and electroconductive polymers
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Novel mono- or difunctional phenylacetylene-substituted Schiff's base monomers useful in the preparation of electrically conducting polymers is disclosed. On heating, these monomers melt to a viscous liquid state, and on continued heating above about 300°C polymerize to form an electrically insulating thermoset polymer. On further post-cure heat treatment, the polymer becomes electroconductive showing a bulk conductivity of at least 10 2 S/cm.
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