Guanidine/Pd(OAc)(2)-catalyzed room temperature Suzuki cross-coupling reaction in aqueous media under aerobic conditions

A highly efficient Pd(OAc)(2)/guanidine aqueous system for the room temperature Suzuki cross-coupling reaction has been developed. The new water-soluble and air-stable catalyst Pd(OAc)(2)(.)(1f)(2) from Pd(OAc)(2) and 1,1,3,3-tetramethyl-2-n-butylguanidine (1f) was synthesized and characterized by X-ray crystallography. In the presence of Pd(OAc)(2)(.)(1f)(2), coupling of arylboronic acids with a wide range of aryl halides, including aryl iodides, aryl bromides, even activated aryl chlorides, was carried out smoothly in aqueous solvent to afford the cross-coupling products in good to excellent yields and high turnover numbers (TONs) (TONs up to 850 000 for the reaction of 1-iodo-4-nitrobenzene and phenylboronic acid). Furthermore, this mild protocol could tolerate a broad range of functional groups.

Immobilization of dipyridyl complex to magnetic nanoparticle via click chemistry as a recyclable catalyst for Suzuki cross-coupling reactions

A magnetic nanoparticle (MNP)-supported di(2-pyridyl)methanol palladium dichloride complex was prepared via click chemistry. The MNP-supported catalyst was evaluated in Suzuki coupling reaction in term of activity and recyclability in DMF. It was found to be highly efficient for Suzuki coupling reaction using aryl bromides as substrates and could be easily separated by an external magnet and reused in five consecutive runs without obvious loss of activity.

Monooxychlorophosphine as a novel and efficient ligand for palladium-catalyzed suzuki-miyaura cross-coupling of aryl chlorides

A new sterically hindered monooxychlorophosphine was synthesized and the complex generated in situ from its reaction with Pd-2(dba)(3) promoted the Suzuki-Miyaura reactions of arylboronic acids with aryl chlorides in good yields.

Synthesis of fluorene-based oligomeric organoboron reagents via Kumada, Heck, and stille cross-coupling reactions

Boronic pinacol ester group is not reactive in Kumada, Heck and Stille coupling reaction conditions. Fluorene-based sophisticated organoboron compounds were synthesized by means of Palladium catalyzed Kumada, Heck and Stille cross-coupling reactions from halofluorenyl boronic esters.

Combination of CH4 oxidative coupling reaction with C2H6 oxidative dehydrogenation by CO2 to C2H4

A new process has been suggested for converting natural gas to ethylene by combining oxidative coupling of methane with ethane dehydrogenation to provide an efficient method for the utilization of thermicity and CO2. From their thermodynamics, it is clear that the exothermicity from CH4 oxidative coupling reaction (DeltaH(800degreesC) = -174.3 kJ mol(-1)) can support C2H6 dehydrogenation by CO2 (DeltaH(800degreesC) = + 180.2 kJ mol(-1)). Meanwhile, the two reactions can be conducted under the same reaction conditions, such as the reaction temperature and reaction pressure as well as space velocity. In addition, the CO2 yielded from CH4 oxidative coupling reaction can be directly used for C2H6 dehydrogenation. Two kinds of catalyst are developed for this combined process with an achievement, from which C2H4 content in tail gas can reach attractively 16.4%, which can be used directly to produce ethylbenzene by the alkylation of benzene. (C) 2002 Elsevier Science Ltd. All rights reserved.

Palladium within ionic liquid functionalized mesoporous silica SBA-15 and its catalytic application in room-temperature Suzuki coupling reaction

Initially, pore walls of mesoporous silica SBA-15 with template were modified with chlorotrimethylsilane. Then imidazolium salts were similarly incorporated covalently in the inner pore walls of mesoporous silica SBA-15 albeit without the template. Finally, palladium salts were introduced into the pore channels of the previously processed mesoporous silica via electrostatic interaction. The resulting palladium catalysts demonstrated exceptional activity for the room-temperature Suzuki Coupling reaction in aqueous-organic mixed solvents and good recycling ability for at least 4-6 times.

Carbon dioxide/propylene oxide coupling reaction catalyzed by chromium salen complexes

A series of chromium/Schiff base complexes N,N'-bis(salicylidene)-1,2-phenylenediamino chromium(III) X were prepared and employed for the alternating copolymerization of carbon dioxide with racemic propylene oxide in the presence of (4-dimethylamino)pyridine. The effect of the complex structure and reaction conditions on the catalytic activity, the poly(propylene carbonate)/cyclic carbonate (PPC/PC) selectivity, and the polymer head-to-tail linkages was examined. The experiments indicated that N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-phenylenediamino chromium(III) (NO3) exhibited the highest PPC/PC selectivity as well as polymer head-to-tail linkages and N,N'-bis(3,5-dichlorosalicylidene)-1,2-phenylenediimino chromiu(III) (NO3) possessed the highest catalytic activity among these chromium/Schiff base complexes. The structure of the produced copolymer was characterized by the IR, H-1 NMR, and C-13 NMR measurements.

Highly active, hexabutylguanidinium salt/zinc bromide binary catalyst for the coupling reaction of carbon dioxide and epoxides

An experimentally simple and inexpensive catalyst system based on hexabutylguanidinium/ZnBr, has been developed for the coupling of carbon dioxide and epoxides to form cyclic carbonates with significant catalytic activity under mild reaction conditions without using additional organic solvents (e.g. the turnover frequencies (TOF, h(-1)) values as high as 6.6 x 10(3) h(-1) for styrene oxide and 1.01 x 10(4) h(-1) for epichlorohydrin). This catalyst system also offers the advantages of recyclability and reusability. Therefore, it is a very effective, environmentally benign, and simple catalytic process. The special steric and electrophilic characteristics of hexabutylguanidinium bromide ionic liquid result in the prominent performance of this novel catalyst system.

Nickel-promoted ligand-free palladium-catalyzed Suzuki coupling reaction

A Ni-promoted ligand-free palladium catalyst system for Suzuki coupling of aryl bromides has been developed in high efficiency under mild reaction conditions. It was obtained in situ by introducing NiCl2 to PdCl2/PVP using a parallel high-throughput screening technique. A wide range of aryl bromides bearing a variety of functional groups was evaluated.

A highly active palladium-phosphoramidite catalyst for the Suzuki cross-coupling of aryl bromides

A highly efficient palladium-catalyzed Suzuki coupling of aryl bromides with aiylboronic acids using phosphoramidite ligand 2c was developed. The phosphoramidite ligands are cost-effective and easily prepared from inexpensive, commercially available starting materials using a simple, efficient method. It represents an advance toward the discovery of low-cost catalyst systems for eventual availability. (c) 2005 Elsevier B.V. All rights reserved.

Synthesis and applications of 3-[6-(hydroxymethyl)pyridin-2-yl]-1,1 '-bi-2-naphthols or 3,3 '-bis[6-(hydroxymethyl)pyridin-2-yl]-1,1 '-bi-2-naphthols

A series of new 1,1'-bi-2-naphthol (BINOL) derived ligands, 3-[6-(hydroxymethyl)pyridin-2-yl]-BINOLs or 3,3'-bis[6(hydroxymethyl)pyridin-2-yl]-BINOLs, bearing one or two chiral pyridinylmetlianols attached to a binaphthyl skeleton, have been synthesized using the Suzuki cross-coupling reaction. The resulting compounds have been used as ligands in the enantioselective addition of diethylzinc to aldehydes; the products were obtained with up to 96% ee.

An Efficient Ullmann-Type C-O Bond Formation Catalyzed by an Air-Stable Copper(I)-Bipyridyl Complex

An efficient O-arylation of phenols and aliphatic alcohols with aryl halides was developed that uses an air-stable copper(I) complex as the catalyst. This arylation reaction can be performed in good yield in the absence of Cs2CO3. A variety of functional groups are compatible with these reaction conditions with low catalyst loading levels.