Imidazolium-based phosphinite ionic liquid (IL-OPPh2) as Pd ligand and solvent for selective dehalogenation or homocoupling of aryl halides

The use of an imidazolium-based phosphinite ionic liquid (IL-OPPh₂) as ligand for Pd offers an efficient reagent system for the selective dehalogenation or homocoupling of aryl halides in the presence of NaOPrⁱ or Et₃N, respectively. This ionic liquid plays a dual role as both the reaction media and also as the potential complexing agent with Pd via its phosphinite carrying group. The ionic liquid containing its corresponding Pd complex can be easily recovered and reused in several runs.     

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.     

Effect of ionic liquid BMImBr on palladium-catalyzed oxidation of ethylene with LiNO3

Oxidative bromination of ethylene was found to proceed effectively in the presence of a catalytic system Pd(OAc)₂–LiNO₃ in two-component BMImBr–HOAc and three-component BMImBr–HOAc–H₂O solvents. At a large content of BMImBr, conversion of ethylene was found to yield 1,2-dibromoethane with a selectivity over 95%. The composition of the Pd(OAc)₂–LiNO₃ solutions was followed during the reaction of ethylene by means of UV–Vis spectroscopy.     

Co2(CO)8 as a convenient in situ CO source for the direct synthesis of benzamides from aryl halides (Br/I) via aminocarbonylation

A fast, mild, and functional group tolerant method for the direct synthesis of benzamides from aryl halides (Br, I) via aminocarbonylation, using solid Co₂(CO)₈ as a convenient CO source, has been demonstrated. The developed method is applicable to a wide variety of 1° and cyclic and acyclic 2° amines. Nitro substituted (o, m and p) aryl halides have easily been converted to the corresponding benzamides, without the reduction of the nitro group, in high yields using this in situ carbonylation methodology under microwave irradiation.     

A new diphenylphosphinite ionic liquid (IL-OPPh2) as reagent and solvent for highly selective bromination, thiocyanation or isothiocyanation of alcohols and trimethylsilyl and tetrahydropyranyl ethers

A new diphenylphosphinite ionic liquid (IL-OPPh₂) is introduced. This ionic liquid is used as both a reagent and a solvent to convert alcohols and trimethylsilyl and tetrahydropyranyl (THP) ethers into their corresponding alkyl bromides, thiocyanates or isothiocyanates in the presence of Br₂ and SCN⁻ at 80 °C. In this ionic liquid, bromination and thiocyanation of alcohols occurs highly selectively in the presence of trimethylsilyl and THP-ethers and also between different classes of alcohols. The use of this ionic liquid allows easy separation of the desired products from the phosphinate by-product.     

Sodium 2-(2-pyridin-3-ylethylamino)sulfonate: an efficient ligand and base for palladium-catalyzed Heck reaction in aqueous media

The first successful Pd(OAc)₂, N-donor ligand and base mediated Heck coupling reaction of aryl halides and alkenes in water is described. The corresponding Heck products were obtained in good to excellent yields.     

Microwave-enhanced and ligand-free copper-catalyzed cyanation of aryl halides with K4[Fe(CN)6] in water

Copper-catalyzed cyanation of aryl halides was improved to be more economical and environmentally friendly by using water as the solvent and ligand-free Cu(OAc)₂·H₂O as the catalyst under microwave heating. The suggested methodology was applicable to a wide range of substrates including aryl iodides and activated aryl bromides.     

Microwave-assisted Pd(OH)2-catalyzed direct C−H arylation of free-(NH2) adenines with aryl halides

A direct C−H arylation of free-(NH₂) adenines using Pd(OH)₂/C (Pearlman’s catalyst) and stoichiometric amount of copper iodide under ligandless microwave activation is described. This new protocol proved to be highly effective to synthesize a variety of 8-aryladenine derivatives 3 without prior protection of the amino substituent. The arylation reaction takes place rapidly within few minutes and allows the coupling to proceed regioselectively at the 8-position with a wide range of aryl halides including aryl iodides, bromides and the less reactive aryl chlorides.     

Sodium 2-(2-pyridin-3-ylethylamino)ethyl sulfonate: an efficient ligand and base for palladium-catalyzed Suzuki reaction in aqueous media

PdCl₂, N-donor ligand and base mediated Suzuki coupling reaction of aryl halides and arylboronic acid in water are described. The corresponding Suzuki products were obtained in good to excellent yields.     

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.     

Microwave-assisted, Mo(CO)6-mediated, palladium-catalyzed amino-carbonylation of aryl halides using allylamine: from exploration to scale-up

Palladium-catalyzed aminocarbonylations of various (hetero)aryl halides with allylamine using Mo(CO)₆ as a solid, in situ CO source, were explored. Microwave-enhanced conditions proved to be highly useful in promoting the conversions in a mere 10-20 min with various (hetero)aryl iodides, bromides and chlorides. The scale-up of a microwave-enhanced aminocarbonylation to 25 mmol scale was performed successfully.     

Triallyl(aryl)silanes serve as a convenient agent for silicon-based cross-coupling reaction of aryl halides

Triallyl(aryl)silanes, stable and easily accessible arylsilanes, were found to react with aryl bromides in the presence of a palladium catalyst (PdCl₂-PCy₃) and tetrabutylammonium fluoride (TBAF) in good yields. The scope of the reaction is broad, and a wide variety of functional groups are tolerant. Allyl groups on Si are readily cleaved upon treatment with TBAF to form fluorosilanes, silanepolyols, siloxanes and/or their mixed forms, which might be responsible for high efficiency of the reaction.     

A facile approach to asymmetrical biaryls via coupling reaction of aryl halides with sodium tetraphenylborate catalyzed by MCM-41-supported sulfur palladium（0） complex

Various functionalized asymmetrical biaryls can be synthesized in high to excellent yields via coupling reaction of aryl iodides or bromides with NaBPh4 catalyzed by MCM-41-supported sulfur palladium(0)complex.This palladium complex can be easily recovered and reused many times without loss of activity.     

Efficient method for the reduction of carbonyl compounds by triethylsilane catalyzed by PdCl2

The versatility of the palladium(II) chloride and triethylsilane system has been tested in the reduction of aromatic carbonyl compounds. The reaction takes place under mild conditions. This facile and efficient method affords high yields for the reduction of aldehydes and ketones to the corresponding alkanes.     

Baylis-Hillman reaction in [bdmim][PF6] ionic liquid

A new use of ionic liquid [bdmim][PF₆] as solvent for the Baylis-Hillman reaction is presented. Unlike the commonly used [bmim][PF₆] that evidently reacts with electrophilic aldehydes under basic conditions, ionic liquid [bdmim][PF₆] is inert and the Baylis-Hillman reaction in [bdmim][PF₆] proceeds smoothly with better yield.     

Thermal stability of ionic liquid BMI(BF4) in the presence of nucleophiles

We have found that a common ionic liquid--one containing a N-N′-dialkylimidazolium cation--decomposes in the presence of nucleophiles at much lower temperatures than previously believed. The decomposition occurs through S_N2 attack of the nucleophile on the electrophilic alkyl groups attached to the imidazolium ring.     

Halofluorination of alkenes with ionic liquid EMIMF(HF)2.3

Halofluorination of alkene by means of N-halosuccinimide and ionic liquid, 1-ethyl-3-methylimidazorium oligo hydrogenfluoride (EMIMF(HF)_2.3), was demonstrated. Various alkenes were converted into β-halo organofluorides in good yields after non-aqueous work-up.     

Effects of solvent and base on the palladium-catalyzed amination: PdCl2(Ph3P)2/Ph3P-catalyzed selective arylation of primary anilines with aryl bromides

A readily accessible catalytic system, PdCl₂(Ph₃P)₂/Ph₃P, was developed for the selective arylation of primary anilines with aryl bromides. The strong influence of solvents and bases on the catalytic activity was observed. In refluxing o-xylene, triphenylphosphine shows high efficiency for Pd-catalyzed intermolecular amination reactions. By changing the bases, mono- and diarylation of primary amines could be selectively achieved in high yields. Moreover, the catalytic system showed good toleration for the steric hindrance of anilines. A series of N,N,N′,N′-tetraaryl-1,1′-biphenyl-4,4′-diamines, important intermediates of OLED hole transport materials, were synthesized facilely via coupling reactions between 4,4′-diaminobiphenyls and aryl bromides.     

X-ray structure of trans-chloro(1-naphthyl) bis(triphenylphosphine)nickel(II) and its application for catalytic dehalogenation of aryl chlorides

X-ray structure of trans-chloro(1-naphthyl)bis(triphenylphosphine)nickel(II) (4) was determined. The complex crystallizes in the triclinic system, space group P 1 with a = 12.0623(3), b = 13.8844(4), c = 14.5261(4) Å, α = 104.787(2), β = 104.861(2), γ = 107.602(2)°, and Z = 2. Dehalogenation of aryl chlorides was successfully performed in isopropyl alcohol (IPA) by using 4 as a precatalyst in the absence of reducing agent. The dehalogenation proceeded smoothly at ambient temperature to provide desired arenes in almost quantitative yields.