- Regioselective Ortho‐C–H sulfenylation of free phenols catalyzed by Co(II)-immobilized on silica-coated magnetic nanoparticles
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Fe3O4?SiO2-UT?CoII is prepared by the silica-coated magnetic nanoparticles, urea-triazole, and CoCl2. This organic-inorganic hybride composite showed a good to excellent catalytic activity toward regioselective ortho-sulfenylation of free phenols and naphthols using pivalic anhydride as a directing group, also K2S2O8 and PPh3 were employed as oxidant and additive respectively. The newly synthesized catalyst was fully characterized by using different techniques such as FT-IR, TGA, DTG, TEM, SEM, EDS, ICP and VSM analyses. The competitive price, accessibility and lower toxicity of cobalt compared to expensive transition metals using for C–H bond activation and functionalization constitute precious advantages for this method. Moreover, this heterogeneous catalyst could be magnetically recovered and reused without significant loss of its catalytic activity after five cycles.
- Khaef, Sepideh,Rostami, Abed,Khakyzadeh, Vahid,Zolfigol, Mohammad Ali,Taherpour, Avat Arman,Yarie, Meysam
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- Palladium-Catalyzed Esterification of Carboxylic Acids with Aryl Iodides
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The first palladium-catalyzed esterification of carboxylic acids with aryl iodides is described. A palladium-based catalytic system consisting of IBnF (1,3-bis((pentafluorophenyl)methyl)imidazole-2-ylidene) ligand was found to significantly acc
- Kitano, Hiroyuki,Ito, Hideto,Itami, Kenichiro
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supporting information
p. 2428 - 2432
(2018/04/27)
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- Copper-Mediated Functionalization of Aryl Trifluoroborates
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This paper describes the Cu(OTf)2-mediated coupling of aryl and heteroaryl trifluoroborates with tetrabutylammonium or alkali metal salts to form C-O, C-N, and C-halogen bonds. The reactions proceed under mild conditions (often room temperature over 16 hours) with carboxylate, halide, and azide salts, all nucleophiles that have been underrepresented in the copper cross-coupling literature. Preliminary results show that copper salts bearing weakly coordinating X-type ligands are essential for enabling these transformations to proceed under mild conditions.
- Schimler, Sydonie D.,Sanford, Melanie S.
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supporting information
p. 2279 - 2284
(2016/10/06)
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- Erbium(III) triflate as an extremely active acylation catalyst
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Erbium(III) triflate is a powerful catalyst for the acylation of alcohols and phenols. The reaction works well for a large variety of simple and functionalized substrates by using different kinds of acidic anhydrides {Ac 2O, (EtCO)2O, [(CH3)3CO] 2O, Bz2O, and (CF3CO)2O} without isomerisation of chiral centres. Moreover, the catalyst can be easily recycled and reused without significant loss of activity.
- Procopio, Antonio,Dalpozzo, Renato,De Nino, Antonio,Maiuolo, Loredana,Russo, Beatrice,Sindona, Giovanni
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p. 1465 - 1470
(2007/10/03)
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- A New and Efficient Esterification Reaction via Mixed Anhydrides by the Promotion of a Catalytic Amount of Lewis Acid
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In the presence of a catalytic amount of Lewis acid, various carboxylic esters or S-phenyl carbothioates are prepared in excellent yields by the respective reactions of equimolar amounts of silyl carboxylates and alkyl silyl ethers or phenyl silyl sulfides with 4-trifluoromethylbenzoic anhydride.
- Miyashita, Mitsutomo,Shiina, Isamu,Miyoshi, So,Mukaiyama, Teruaki
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p. 1516 - 1527
(2007/10/02)
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- Reaction of (Acyloxy)alkyl α-Halides with Phenols: Effect of Nucleofugicity and Nucleophilicity on Product Distribution
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The product distribution obtained from the reaction of (acyloxy)alkyl α-halides (1 or 5) with phenols was found to depend on the nucleophilicity of the phenol, the nucleofugicity of the leaving group, and the ability of the electrophile to stabilize a carbenium ion.More nucleophilic phenols tended to give more acylation while better leaving groups and more stable incipient carbenium ions in the electrophile tended to favor the formation of alkylated products.In addition, the reaction of methanol with 1a was found to give a mixture of acylated and alkylated products (40 : 60).Thus, a general trend for all the nucleophiles for which information is available suggests that better nucleophiles undergo relatively more acylation and that poorer nucleophiles undergo more alkylation.These results are suggested to be consistent with the observations of Westaway on the effect of leaving group nucleofugicity and nucleophilicity of the nucleophile on bond lengths in the SN2 transition state.Facile rearrangements of acylated to alkylated products and of one alkylated product to another caused by the phenolate anion were also observed in the 3-phenoxy-1(3H)-isobenzofuranone-phenyl 2-formylbenzoate series.
- Sloan, Kenneth B.,Koch, Suzanne A. M.
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p. 3777 - 3783
(2007/10/02)
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