Efficient ligand-free nickel-catalyzed C-S cross-coupling of thiols with aryl iodides

NiCl₂·6H₂O efficiently catalyzes the C-S bond formation by the cross-coupling of aryl iodides with thiols in tetrabutylammonium bromide (TBAB) in excellent yield. The reaction functions in air and the NiLn-TBAB can be recovered and recycled without the loss of activity.     

Efficient copper-catalyzed C-S cross-coupling of heterocyclic thiols with aryl iodides

A copper-catalyzed cross-coupling of heterocyclic thiols with aryl iodides is reported. The reaction was carried out in the presence of CuI (5 mol %), 1,10-phenanthroline (10 mol %) and K₂CO₃ (1.3 equiv) in DMF at 120 °C. A variety of heterocyclic sulfides were prepared in high selectivities and yields.     

Ligand-free copper-catalyzed C-S coupling of aryl iodides and thiols

A protocol for the copper-catalyzed aryl-sulfur bond formation between aryl iodides and thiophenols is reported. The reaction is catalyzed by a low amount (1-2.5 mol %) of readily available and ligand-free copper iodide salt. A variety of diaryl thioethers are synthesized under relatively mild reaction conditions with good chemoselectivity and functional group tolerance.     

Copper-catalyzed arylation of phenylurea using KF/Al2O3

A mild and efficient method for the copper-catalyzed arylation of phenylurea is described. The coupling reaction of phenylurea with different functionalized aryl iodides in the presence of air stable CuI, N,N′-dibenzylethylenediamine as a ligand, and KF/Al₂O₃ as a base gives symmetrical and unsymmetrical diarylureas in relatively high yields.     

Copper-catalyzed N-arylation of diazoles with aryl bromides using KF/Al2O3: an improved protocol

Copper-catalyzed N-arylation of diazoles can be accomplished using air-stable CuI as a copper source and 1,10-phenanthroline in the presence of KF/Al₂O₃ as a base. This is a simple and efficient method for the coupling of aryl bromide with diazoles. Different functionalized aryl bromides were coupled with diazoles using this system.     

Preparation, characterization and application of KNH2/Al2O3 and KF/Al2O3 as strong solid bases

This review describes the preparation, characterization and application of KNH₂ loaded on alumina and KF loaded on alumina. These strong solid bases catalyze a variety of organic reactions in a very selective manner. The reactions include isomerizations of alkenes and alkynes, dimerization of alkynes, Tishchenko reaction, and the reaction of silanes to form of Si–C, Si–N and Si–O bonds.     

Iron/copper-catalyzed C-C cross-coupling of aryl iodides with terminal alkynes

Synergic effect of iron and copper salts as catalysts for the Sonogashira-Hagihara cross-couplings of aryl iodides with terminal alkynes is demonstrated. High yields of cross-coupled products are obtained under conditions that are smoother than those using only CuI as catalyst. Furthermore no expensive or/and toxic ligand is required.     

Simple, efficient and recyclable catalytic system for performing copper-catalyzed C-S coupling of thiols with aryl iodides in PEG and PEG-H2O

A new protocol for the coupling of aryl iodides with thiophenols or alkanethiols is reported. The reaction is catalyzed by CuI-PEG or CuI-PEG-H₂O system in the absence of ligands and volatile organic solvents. A variety of functionalized aryl sulfides are prepared in excellent yields. The isolation of the products is readily performed by the extraction with diethyl ether or petroleum ether, and the CuI-PEG catalyst can be reused without significant loss in activity. The simple catalytic system is economically competitive and environmentally friendly.     

Synthesis of (Z)-organylthioenynes using KF/Al2O3/solvent as recyclable system

PEG-400 and glycerol were successfully used as recyclable solvents for the synthesis of several organylthioenynes in good to excellent yields and high selectivity using solid supported catalyst (KF/Al₂O₃). This easy, general and improved method furnishes the corresponding alkenyl sulfides preferentially with Z configuration. The catalytic system and the glycerol or PEG-400 can be reused up to three times without previous treatment with comparable activity.     

A general rhodium-catalyzed cross-coupling reaction of thiols with aryl iodides

The general procedure for the rhodium-catalyzed cross-coupling of thiols with aryl iodides is described. The catalytic system consists of 5 mol % of [RhCl(cod)]₂ and 10 mol % of PPh₃ as a ligand. A variety of aryl iodides reacted with thiols, giving aryl thioethers in good to excellent yields. It is important to note that the deactivated aryl iodides such as 4-iodoanisole is worked smoothly to provide the corresponding aryl thioethers in excellent yields. Functional groups such as free-amines, chloro, are all tolerated under the employed reaction conditions.     

Efficient copper-catalyzed N-arylation of sulfoximines with aryl iodides and aryl bromides

Two simple and inexpensive systems for copper-catalyzed N-arylations of sulfoximines with aryl bromides and aryl iodides have been developed. Using 10 mol % of a copper(I) salt in combination with 20 mol % of a 1,2-diamine and Cs2CO3 provides N-arylated sulfoximines in high yields. Various functional groups and heteroatoms are tolerated. The method is complementary to the known protocols for N-arylations of sulfoximines, which require stoichiometric quantities of copper salts or cost-intensive palladium/BINAP catalysts.     

Synthesis of vinyl sulfides via hydrothiolation of alkynes using Al2O3/KF under solvent-free conditions

We present here a clean, solvent-free hydrothiolation of alkynes using solid supported catalyst (Al₂O₃/KF). This efficient and improved method selectively furnishes the corresponding anti-Markovnikov vinyl sulfides in good to excellent yields. The method is applicable for aliphatic and aromatic thiols and the catalytic system can be re-used up to two times without previous treatment and with comparable activity.     

Sulfuration of Pt/Al2O3, Pt?Re/Al2O3 and Pt?Ir/Al2O3 catalysts

Three reforming catalysts Pt/Al₂O₃, Pt–Ir/Al₂O₃ and Pt–Re/Al₂O₃ have been sulfurated by H₂S and tested by their activities in benzene hydrogenation. By treatment at 500°C under hydrogen flow only a part of the initial activity of the non-sulfurated catalyst is retained. So only a part of the adsorbed sulfur is easily removed in these conditions. The remaining sulfur for each of the catalysts (Pt/Al₂O₃, Pt–Ir/Al₂O₃ and Pt–Re/Al₂O₃) gives the same atomic ratio of 0.5 sulfur atom per accessible metallic atom.

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Pt/Al₂O₃, Pt–Ir/Al₂O₃ Pt–Pe/Al₂O₃ . 500°C H₂ . . ., . (Pt/Al₂O₃, Pt–Ir/Al₂O₃ Pt–Pe/Al₂O₃) 0,5.

     

Pd2(dba)3/Xantphos-catalyzed cross-coupling of thiols and aryl bromides/triflates

The cross-coupling of aliphatic and aromatic thiols and aryl bromides/triflates mediated by a Pd₂(dba)₃/Xantphos catalytic system in refluxing xylene (140 °C) affords the corresponding aryl thioethers in good to excellent yields.     

Sulfurization of Pt/Al2O3?Cl catalysts. IV. Adsorption sites of H2S on Al2O3, Al2O3?Cl and Pt/Al2O3?Cl

Chemisorption of H₂S on Al₂O₃, Al₂O₃–Cl and Pt/Al₂O₃–Cl has been studied by gravimetry and IR spectroscopy. The influence of the amount of Cl on the H₂S adsorption equilibrium value and the nature of the adsorption sites at low and high coverages are discussed.

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H₂S Al₂O₃, Al₂O₃–Cl Pt/Al₂O₃–Cl . Cl H₂S, .

     

Microwave-assisted deformylation of N-aryl formamide by KF on basic Al2O3

The formyl group was successfully removed from N-aryl formamide by KF on a solid support of basic Al₂O₃ in 4-20 min with microwave irradiation. The conditions mimic base-catalyzed hydrolysis of formamide and are compatible with carbamates and t-butyl esters, but not methyl, ethyl, and benzyl esters.     

Efficient copper-catalyzed cross-coupling of 1-Boc-piperazine with aryl iodides and its application in the synthesis of trazodone

A convenient and practical strategy is developed for the cross-coupling of N-Boc protected piperazines with aryl iodides using CuBr/1,1′-bi-2-naphthol as the catalyst and K₃PO₄ as the base. The protocol affords N-arylated piperazine products in moderate to good yields under the optimized conditions. The application of this catalytic system to the synthesis of trazodone is also successfully demonstrated using commercially available substrates.     

Efficient ligand-free copper-catalyzed N-arylation of amides with aryl halides in water

A convenient and efficient protocol has been developed for the cross-coupling of amides and aryl iodides using a ligand-free copper(I) oxide catalyst in water. A variety of amide derivatives afforded the corresponding N-arylated products in moderate to good yields (up to 88%).     

TPR studies on steam reforming of 2-propanol on Rh/Al2O3, Ru/Al2O3 and Pd/Al2O3

Reaction pathways for steam reforming of 2-propanol (isopropyl alcohol, IPA) on Rh/Al₂O₃, Ru/Al₂O₃ and Pd/Al₂O₃ have been studied by temperature-programmed reactions (TPRs) of IPA and acetone in the presence of steam. The results of TPRs suggest that that of IPA on Rh/Al₂O₃ and Ru/Al₂O₃ proceeds via acetone, while the steam reforming of IPA on Pd/Al₂O₃ takes place via propene from acetone. This revised version was published online in August 2006 with corrections to the Cover Date.