Copper oxide nanoparticles catalyzed synthesis of aryl sulfides via cascade reaction of aryl halides with thiourea

Recyclable copper oxide nanoparticles catalyzed simple and highly efficient protocol for the synthesis of symmetrical aryl sulfides was developed by the cross-coupling of aromatic halides with inexpensive and commercially available thiourea which was used as an effective sulfur surrogate. The present cross-coupling protocol of thiourea, via cascade reaction with various substituted aryl halides, producing desired aryl sulfides, has an added advantage of avoiding foul-smelling thiols.     

Microwave assisted,ligand free,copper catalyzed reaction of aryl halides with phenyl urea

The ligand free coupling reaction of phenyl urea with different functionalized aryl halides in the presence of air stable Cu₂O and t-BuOK as a base gives symmetrical and unsymmetrical diarylureas in relatively high yields.This method is milder than the palladium catalyzed arylation and avoids the use of toxic phosphine ligand.     

Cu-nanoparticle catalyzed O-arylation of phenols with aryl halides via Ullmann coupling

Recyclable Cu-nanoparticles provide an efficient, economic, and novel method for the synthesis of diaryl ethers via Ullmann type coupling. This method provides a wide range of substrate applicability and avoids the use of a heavy metal co-catalyst and gives diaryl ethers in satisfactory yields.     

Tetraphosphine/palladium catalysed Suzuki cross-coupling reactions of aryl halides with alkylboronic acids

Through the use of [PdCl(C₃H₅)]₂/cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane as a catalyst, a range of aryl bromides and chlorides undergoes Suzuki cross-coupling with alkylboronic acids in good yields. Several alkyl substituents such as ethyl, n-butyl, n-octyl, isobutyl or 2,2-dimethylpropyl on the alkylboronic acids have been successfully used. The functional group tolerance on the aryl halide is remarkable; substituents such as fluoro, methyl, methoxy, acetyl, formyl, benzoyl, nitro or nitrile are tolerated. Furthermore, this catalyst can be used at low loading, even for reactions of sterically hindered aryl bromides.     

Palladium catalyzed alkynylation of aryl halides (Sonogashira reaction) in water

The palladium catalyzed alkynylation of aryl halides (Sonogashira reaction) has been achieved in pure water without any additives or phase transfer catalysts. The reaction, which requires only 0.5 mol % of Pd(PPh₃)₄ catalyst, is remarkably fast (30 min at 70 °C) producing high yields of the aryl alkyne products.     

α-Arylation of β-diketones with aryl halides catalyzed by CuO/aluminosilicate

α-Arylation of β-diketones has been carried out over CuO/aluminosilicate catalyst under ligand-free condition. The reaction conditions were optimized with different solvents, bases, catalyst amounts, and temperatures using acetylacetone and 4-bromobenzaldehyde as a model system. The scope of the catalytic system was extended to include various substituted aryl halides. 27 examples were successfully demonstrated and the yields were ranging from 55% to 94%. C–Br bond was regioselectively activated in the presence of C–Cl bond. Similarly acetylacetone was chemoselectively arylated by 4-bromobenzaldehyde in the presence of dibenzoylacetone. Heterogeneous nature of the catalyst was confirmed by hot-filtration test. The catalyst was also found to be reusable.     

Copper-catalyzed N-arylation of 2-arylindoles with aryl halides

10 mol% Cul combined with the DMEDA ligand can efficiently catalyze the N-arylation of 2-arylindoles with aryl iodides and aryl bromides in good to excellent yields. The aryl halides bearing electron-rich or electron-deficient functional groups can be well tolerated under this mild reaction conditions.     

Facile synthesis of symmetrical functionalized biaryls from aryl halides catalyzed by commercial zinc dust using ammonium formate

Reductive homocoupling of aryl halides in the presence of commercial zinc dust and ammonium formate in methanol produces biaryls in good to excellent yields. Aryl halides having either electron-donating or electron-withdrawing groups underwent smooth coupling to afford the corresponding symmetrical biaryls. Addition of 1 equiv of sodium hydroxide enhanced the coupling reaction rate. Commercial zinc dust is inexpensive, widely available and can be used without any auxiliary catalysts such as Pd(0) and/or Ni(0).     

Sonogashira reaction of aryl halides with propiolaldehyde diethyl acetal catalyzed by a tetraphosphine/palladium complex

All-cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane/[PdCl(C₃H₅)]₂ efficiently catalyzes the Sonogashira reaction of propiolaldehyde diethyl acetal with a variety of aryl bromides and chlorides. A minor electronic effect of the substituents of the aryl bromide was observed. Similar reaction rates were observed in the presence of activated aryl bromides such as 4-trifluoromethylbromobenzene and deactivated aryl bromides such as bromoanisole. Turnover numbers up to 95,000 can be obtained for this reaction. Even aryl chlorides and heteroarylbromides or chlorides have been successfully alkynylated with this catalyst. Moreover, a wide variety of substituents on the aryl halide such as fluoro, trifluoromethyl, acetyl, benzoyl, formyl, nitro, dimethylamino or nitrile are tolerated.     

N-arylation of indoles with aryl halides using copper/glycerol as a mild and highly efficient recyclable catalytic system

A simple, efficient, and inexpensive copper catalyzed protocol has been developed for cross-coupling of indoles with aryl halides by using glycerol as a green recyclable solvent and DMSO as an additive. The reaction was carried out at low catalyst loading furnishing various N-aryl indoles in good to excellent yield. This copper/glycerol mixture was recycled up to four runs without any loss in its catalytic activity.     

Palladium catalyzed ligand-free Suzuki cross-coupling reactions of benzylic halides with aryl boronic acids under mild conditions

A highly efficient Suzuki cross-coupling reaction between benzylic halides and aryl boronic acids using palladium chloride as catalyst in acetone:water (3:1) as the solvent system has been developed. High yields of products, mild reaction conditions and short reaction times in the absence of ligand are important features of this method.     

Ligand free open air copper(II) mediated aryl formamidation and amination of aryl halides

A simple synthetic procedure for direct formamidation and amination of aryl halides mediated by copper(II) salts was developed in open air, without an external ligand in formamide with potassium carbonate as a base. This approach is particularly efficient when electron active aryl halides are used as substrates. In these cases almost quantitative formamidation was observed.     

Room temperature dehalogenation of (hetero)aryl halides with magnesium/methanol

Magnesium in methanol was found to be an effective and inexpensive reagent for the dehalogenation of (hetero)aryl chlorides, bromides and iodides under mild conditions. The halogen/hydrogen exchange proceeded at room temperature and tolerated functional groups such as esters, nitriles, alcohols, and alkenes.     

Polyethylene glycol (PEG) promoted hydrodehalogenation of aryl halides

Transition-metal-free hydrodehalogenation of aryl halides (eg. bromides) can take place efficiently in the presence of green polyethylene glycol (PEG-800) and t-BuOK without adding any extra solvents and additives. A radical mechanism is proposed for this transition-metal-free dehalogenation of aryl halides and the role of polyethylene glycol is both reaction promotor and activated alkyl CH donor.     

Dimer formation in the reaction of aryl halides catalyzed by nickel complexes

The synthesis of diaryls catalyzed by electrochemically generated zero-valent nickel with 2,2-diapyridyl as the ligand was carried out from aryl halides in high yield. Feasibility was demonstrated for synthesizing the catalyst itself by the anodic dissolution of nickel in the presence of 2-bromopyridine in a diaphragmless cell.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Science Center, Russian Academy of Sciences, 420083 Kazan. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1674–1676, July, 1992.     

The metal-halogen exchange reaction between ortho-substituted aryl halides and Ph2CuLi · LiCN: scope and applicability for coupling reactions

Metal-halogen exchange between Ph₂CuLi · LiCN and ortho-substituted aryl iodides or bromides may be used to conveniently afford substituted metallated aryls which can subsequently undergo reaction with electrophiles.     

Ruthenium-catalyzed coupling reaction of 2,3,5-trisubstituted furans with aryl halides through C-H bond cleavages

A variety of functionalized furans were synthesized by way of a ruthenium-catalyzed coupling reaction of 2,3,5-trisubstituted furans with aryl halides through C-H bond cleavages. The feature of the reaction was facilitative preparation of furan derivatives good functional group tolerance. All reactions gave the desired products in moderate to good yields (56-89%) in the presences of [RuCl₂(p-cymene)] and K₂CO₃ in NMP at 120 °C.     

A general and efficient CuI/BtH catalyzed coupling of aryl halides with thiols

We report an exceptionally mild, general and efficient copper catalyzed cross coupling reaction of aryl bromides and thiols using 0.5 mol % CuI and 1 mol % benzotriazole. Experimental simplicity, generality, functional group tolerance and low cost of the catalyst are advantages of the protocol.     

A simple catalyst system for the palladium-catalyzed coupling of aryl halides with terminal alkynes

A convenient catalyst system consisting of Pd(OAc)₂, PPh₃, K₃PO₄ and DMSO was found to be effective for the coupling reaction of aryl halides with terminal alkynes as well as the deacetonative coupling reaction using a 4-aryl-2-methylbut-3-yn-2-ol as a terminal alkyne precursor. An iminophosphine as a ligand worked more effectively for some combination of substrates than triphenylphosphine.     

Pd/C-mediated coupling of aryl halides with terminal alkynes in water

2-Aminoethanol facilitated the alkynylation of aryl halides (Sonogashira reaction) under palladium/charcoal-copper catalysis in water affording a mild and practical method for the synthesis of arylalkynes. A variety of terminal alkynes were coupled with aryl iodides and bromides possessing no hydrophilic functional groups to give the coupled products in good to excellent yields.