- Imidazolium chloride-Co(iii) complex immobilized on Fe3O4@SiO2 as a highly active bifunctional nanocatalyst for the copper-, phosphine-, and base-free Heck and Sonogashira reactions
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A heterogeneous, magnetically recoverable Fe3O4@SiO2@Im[Cl]Co(iii)-melamine nanocomposite was prepared by immobilization of a novel Co(iii) Schiff base complex on Fe3O4@SiO2 nanoparticles followed by treatment with melamine, and was found to be an efficient catalyst for the Heck and Sonogashira reactions. The reactions were performed in the presence of the catalyst (0.5 mol% Co) along with Mn additive in the absence of any base, phosphine ligand, or Cu/co-catalyst in ethanol under reflux conditions. The nanocatalyst was well studied by FTIR, CHN, XRD, XPS, TGA, EDX, VSM, ICP, NMR, FE-SEM, TEM, BET, CV, and DLS analyses. The catalyst was compatible with a variety of substrates, with which all the Heck and Sonogashira coupling products were obtained in high to excellent yields. Also, protocols such as hot filtration, three-phase testing, and mercury poisoning provided a complete insight into the nature of the heterogeneous catalyst. The recycling and reuse of the catalyst were studied for both coupling reactions several times. Moreover, the mechanism of the coupling reactions was entirely investigated.
- Kazemnejadi, Milad,Alavi, Seyyedeh Ameneh G.,Rezazadeh, Zinat,Nasseri, Mohammad Ali,Allahresani, Ali,Esmaeilpour, Mohsen
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p. 1718 - 1734
(2019/04/08)
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- p-Toluenesulfonic acid catalysed fluorination of α-branched ketones for the construction of fluorinated quaternary carbon centres
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A p-toluenesulfonic acid catalyzed fluorination of α-branched ketones for the construction of fluorinated quaternary carbon centers has been developed, featuring a broad substrate scope, environmentally benign reaction conditions, and operational simplicity.
- Tang, Shi-Zhong,Bian, Hong-Li,Zhan, Zong-Song,Chen, Meng-En,Lv, Jian-Wei,Xie, Shaolei,Zhang, Fu-Min
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supporting information
p. 12377 - 12380
(2018/11/30)
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- Metal-Free Three-Component Oxyalkynylation of Alkenes
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An unprecedented (NH4)2S2O8 mediated metal-free three-component alkene oxyalkynylation using H2O or alcohol as oxygenation agent is described. Mechanistic studies suggested that the reversed regiosele
- Li, Yangshan,Lu, Ran,Sun, Shutao,Liu, Lei
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supporting information
p. 6836 - 6839
(2018/10/25)
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- N-heterocyclic carbene-Pd(II) complex based on theophylline supported on Fe3O4@SiO2 nanoparticles: Highly active, durable and magnetically separable catalyst for green Suzuki-Miyaura and Sonogashira-Hagihara coupling reactions
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In this paper, a novel heterogeneous palladium catalyst was synthesized by anchoring N-heterocyclic carbene-Pd(II) complex based on theophylline on magnetic Fe3O4@SiO2 nanoparticles. The synthesized magnetic composite was characterized by fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray analysis (EDX), thermogravimetric analysis (TGA), vibration sample magnetometry (VSM), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), N2 adsorption-desorption isotherm analysis (BET), UV–vis spectroscopy and elemental analysis. Also, loading content of palladium on the catalyst was measured by inductive coupled plasma (ICP) analysis. The synthesized catalyst was used successfully for the Suzuki cross-coupling reactions of various aryl halides (I, Br, Cl) with phenylboronic acids. This reaction was best performed in water as a green solvent in the presence of just 0.37–0.5 mol% of the catalyst at 60 °C. Also, we have reported this recyclable catalytic system as a stable phosphine-free Pd catalyst for the Sonogashira cross-coupling of aryl halides (I, Br, Cl) with terminal aromatic and aliphatic alkynes under solvent-free conditions. All coupling reactions proceeded with good to excellent yields. The catalyst showed good stability and was recovered and reused for eight reaction cycles without a significant loss in its catalytic activity. Also, the leaching of the catalyst has been examined by a hot filtration test and ICP-AES analysis.
- Esmaeilpour, Mohsen,Sardarian, Ali Reza,Firouzabadi, Habib
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- Palladium nanoparticles immobilized on EDTA-modified Fe3O4@SiO2 nanospheres as an efficient and magnetically separable catalyst for Suzuki and Sonogashira cross-coupling reactions
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In this study, a novel heterogeneous palladium catalyst was synthesized by anchoring palladium onto ethylenediaminetetraacetic acid (EDTA)-coated Fe3O4@SiO2 magnetic nanocomposite and used for the Suzuki and Sonogashira cross-coupling reactions. The properties of the magnetic catalyst were characterized by FT-IR, XRD, TEM, FE-SEM, DLS EDX, XPS, N2 adsorption-desorption isotherm analysis, TGA, VSM, elemental analysis and the loading level of Pd in catalyst was measured to be 0.51?mmol/g by ICP. The catalyst was used in Suzuki cross-coupling reactions of various aryl halides, including less reactive chlorobenzenes with phenylboronic acid without any additive or ligand under green conditions. Furthermore, we have reported this recyclable catalytic system for Sonogashira cross-coupling reactions of various aryl halides (I, Br, Cl) under copper and ligand-free conditions in the presence of DMF/H2O (1:2/v:v) as a solvent. The magnetic catalyst could also be separated by an external magnet and reused six times without any significant loss of activity.
- Esmaeilpour, Mohsen,Zahmatkesh, Saeed,Fahimi, Nafiseh,Nosratabadi, Mehran
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- The role of Br?nsted and Lewis acidity in the green synthesis of homopropargyl alcohols over HZSM-5
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A highly efficient and simple reaction under exceptionally mild conditions is shown for the synthesis of biologically and pharmaceutically active molecules of homopropargyl alcohol using HZSM-5 as the catalyst. Products analyzed by IR, 1H NMR, 13C NMR and GC-MS showed consistent yields of 98 % of the alcohol, even with respective recycles of the regenerated catalyst. The reaction was also carried out with selected mineral acids, acidic oxides and other acidic catalysts to compare reactivity and the influence of the type of acidity involved in the reaction. The results indicate that the presence of both Br?nsted and Lewis acidity is beneficial for inducing a high rate of reaction when compared to systems having either predominantly Br?nsted or Lewis acidity.
- Viswanadham, Balaga,Singh, Sooboo,Friedrich, Holger B.,Mahomed, Abdul S.
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- Asymmetric Induction via a Helically Chiral Anion: Enantioselective Pentacarboxycyclopentadiene Br?nsted Acid-Catalyzed Inverse-Electron-Demand Diels-Alder Cycloaddition of Oxocarbenium Ions
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An enantioselective catalytic inverse-electron-demand Diels-Alder reaction of salicylaldehyde acetal-derived oxocarbenium ions and vinyl ethers to generate 2,4-dioxychromanes is described. Chiral pentacarboxycyclopentadiene (PCCP) acids are found to be effective for a variety of substrates. Computational and X-ray crystallographic analyses support the unique hypothesis that an anion with point-chirality-induced helical chirality dictates the absolute sense of stereochemistry in this reaction.
- Gheewala, Chirag D.,Hirschi, Jennifer S.,Lee, Wai-Hang,Paley, Daniel W.,Vetticatt, Mathew J.,Lambert, Tristan H.
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supporting information
p. 3523 - 3527
(2018/03/21)
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- Alkynylation of aldehydes mediated by zinc and allyl bromide: a practical synthesis of propargylic alcohols
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Abstract: A practical synthesis of propargylic alcohols was developed by alkynylation of aldehydes mediated by zinc and allyl bromide. Aromatic, aliphatic and vinyl aldehydes react with phenylacetylene or 1-hexyne to obtain various propargylic alcohols at room temperature in up to 98% yield. This method is characterized with inexpensive materials, wide substrate scope, and mild reaction conditions, and is also easy to scale up. In addition, this protocol is applicable to the alkynylation of α-ketone esters and epoxides to generate α-tertiary-hydroxy esters and α-alkynyl alcohols, respectively. Graphical Abstract: [Figure not available: see fulltext.].
- Zhou, Ji-Cai,Zhao, Lei,Li, Yuan,Fu, Ding-Qiang,Li, Zi-Cheng,Huang, Wen-Cai
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p. 4283 - 4294
(2017/06/20)
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- Synthesis of 2,3-dihydro-1: H -pyrroles by intramolecular cyclization of N -(3-butynyl)-sulfonamides
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Hydroamination of 3-butynamine derivatives to give non-aromatic 2,3-dihydropyrroles was achieved by using PdCl2 or AuCl as the catalyst. With microwave-assisted heating, up to 92% isolated yield was obtained from this intramolecular 5-endo-dig
- Chung, Min-Ching,Chan, Yung-Hsiang,Chang, Wen-Jung,Hou, Duen-Ren
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supporting information
p. 3783 - 3790
(2017/07/07)
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- Asymmetric fluorination of α-branched cyclohexanones enabled by a combination of chiral anion phase-transfer catalysis and enamine catalysis using protected amino acids
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We report a study involving the successful merger of two separate chiral catalytic cycles: a chiral anion phase-transfer catalysis cycle to activate Selectfluor and an enamine activation cycle, using a protected amino acid as organocatalyst. We have demonstrated the viability of this approach with the direct asymmetric fluorination of α-substituted cyclohexanones to generate quaternary fluorine-containing stereocenters. With these two chiral catalytic cycles operating together in a matched sense, high enantioselectivites can be achieved, and we envisage that this dual catalysis method has the potential to be more broadly applicable, given the breadth of enamine catalysis. It also represents a rare example of chiral enamine catalysis operating successfully on α-branched ketones, substrates commonly inert to this activation mode.
- Yang, Xiaoyu,Phipps, Robert J.,Toste, F. Dean
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supporting information
p. 5225 - 5228
(2014/05/06)
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- Synthesis of propargylic and allenic carbamates via the C-H amination of alkynes
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Propargylic amines are important intermediates for the synthesis of nitrogen-containing heterocycles. The insertion of a nitrene into a propargylic C-H bond has not been explored, despite the attention directed toward the Rh-catalyzed amination of other t
- Grigg, R. David,Rigoli, Jared W.,Pearce, Simon D.,Schomaker, Jennifer M.
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supporting information; experimental part
p. 280 - 283
(2012/02/16)
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- Synthesis of heterocyclic systems by transition-metal-catalyzed cyclization-migration reactions - A diversity-oriented strategy for the construction of spirocyclic 3(2H)-furanones and 3-pyrrolones
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Two platinum(II)-catalyzed heterocyclization-migration reactions that provide five-membered heterocycle products are described. With 5 mol-% of PtCl2 as a catalyst, 2-alkynyl-2-hydroxy carbonyl compounds 1 are converted into 3(2H)-furanones 2 a
- Binder, Joerg T.,Crone, Benedikt,Kirsch, Stefan F.,Liebert, Clemence,Menz, Helge
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p. 1636 - 1647
(2008/02/06)
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- Cyclization reactions of homopropargyl azide derivatives catalyzed by PtCl4 in ethanol solution: Synthesis of functionalized pyrrole derivatives
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PtCl4-catalyzed cyclization reactions of homopropargyl azide derivatives to pyrrole rings were investigated. Using ethanol as solvent with 2,6-di-tert-butyl-4-methylpyridine as the base was found to be the best set of conditions for effecting this ring-closing reaction. These reaction conditions can be applied to the preparation of functionalized pyrrole derivatives, with no effect on the functional groups.
- Hiroya, Kou,Matsumoto, Shigemitsu,Ashikawa, Masayasu,Ogiwara, Kentaro,Sakamoto, Takao
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p. 5349 - 5352
(2007/10/03)
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- Boron trifluoride-tetrahydrofuran complex: A superior trigger for the Yamaguchi-Hirao alkylation of lithio-acetylides by epoxides
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Use of BF3·THF complex in place of the usual BF3·OEt2 analogue in the Yamaguchi-Hirao alkylation of lithio-acetylides 2 by monosubstituted epoxides 3 gives consistently superior isolated yields (ca. 90%) of homopropargylic
- Evans, Ann B,Knight, David W
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p. 6947 - 6948
(2007/10/03)
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- A practical titanium-catalyzed synthesis of bicyclic cyclopentenones and allylic amines
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A practical titanium-catalyzed synthesis of bicyclic cyclopentenones and allylic amines is described. The process converts enyne substrates to iminocyclopentenes using 10 mol % of the air- and moisture-stable precatalyst Cp2TiCl2 in the presence of n-BuLi and triethylsilyl cyanide. The resulting iminocyclopentenes can be hydrolyzed to cyclopentenones in good yields or reduced to allylic silylamines with Red-Al or DIBALH. Treatment of the crude silylamines with acetyl chloride allows isolation of allylic amides in excellent yields.
- Hicks, Frederick A.,Berk, Scott C.,Buchwald, Stephen L.
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p. 2713 - 2718
(2007/10/03)
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- Stereo- and regioselective metal salt-catalyzed alkynylation of 1,2-epoxides
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A simple, efficient, stereoselective, and highly regioselective method for the synthesis of β-hydroxyacetylenes by the direct opening of 1,2-epoxides with lithium acetylides in anhydrous THF, in the presence of metal salts, is described. This new method a
- Chini,Crotti,Favero,Macchia
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p. 6617 - 6620
(2007/10/02)
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- SYNTHESIS OF α-ALKYLIDENE-γ-LACTONES BY INTRAMOLECULAR ADDITION OF ALKOXYCARBONYL FREE-RADICALS TO ACETYLENES
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α-Alkylidene-γ-lactones are obtained by treatment of chloroformate and selenocarbonate derivatives of homopropargylic alcohols with tri-n-butylstannane.
- Bachi, Mario D.,Bosch, Eric
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p. 641 - 644
(2007/10/02)
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- Radical Annulation: A Method for Preparation of Carbocycles
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β-Acetylenic radicals, e.g., (6b) and (12), generated in three steps from epoxides or in two steps from α-halogenoketones, respectively, react with electron-defficient olefins to produce five-membered carbocycles by a process of conjugate addition and 5-e
- Angoh, Gaeatan A.,Clive, Derrick L. J.
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p. 980 - 982
(2007/10/02)
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- AN EFFICIENT METHOD FOR THE ALKYNYLATION OF OXIRANES USING ALKYNYL BORANES
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Alkynyl boranes, generated in situ from lithium acetylides and boron trifluoride etherate, were found to react with oxiranes under mild reaction conditions to afford β-hydroxyacetylenes in high yields.
- Yamaguchi, Masahiko,Hirao, Ichiro
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p. 391 - 394
(2007/10/02)
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