B-alkyl suzuki-miyaura cross-coupling reactions with air-stable potassium alkyltrifluoroborates

The palladium-catalyzed cross-coupling reaction of substituted potassium alkyltrifluoroborates with aryl halides and aryl triflates proceeds readily with moderate to good yields. The potassium alkyltrifluoroborates 1, 2, and 3a-e were easily synthesized and obtained as air-stable crystalline solids that can be stored for long periods of time. All of the cross-couplings proceed under the same reaction conditions using PdCl(2)(dppf).CH(2)Cl(2) as catalyst in THF-H(2)O in the presence of 3 equiv of Cs(2)CO(3) as base.     

New catalysts for Suzuki-Miyaura coupling reactions of heteroatom-substituted heteroaryl chlorides

The new air-stable PdCl2[PR2(Ph-R')]2 complexes, readily prepared from commercial reagents, exhibit unique efficiency as catalysts for the Suzuki-Miyaura coupling reactions of a variety of heteroatom-substituted heteroaryl chlorides with a diverse range of aryl/heteroaryl boronic acids. The coupling reactions catalyzed by the new complexes exhibit high product yields (88-99%) and high catalyst turnover numbers (up to 10,000 TON).     

Ionic liquid acceleration of solid-phase suzuki-miyaura cross-coupling reactions

[reaction: see text] Room-temperature ionic liquids promote various transition metal-catalyzed reactions in the solution phase. Here, for the first time, we show that these effects are translatable to solid-phase reactions. The Suzuki-Miyaura cross-coupling of 4-iodophenol immobilized on polystyrene-Wang resin with various arylboronic acids was significantly accelerated by the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)(-)]).     

New ligands for a general palladium-catalyzed amination of aryl and heteroaryl chlorides

The synthesis and application of monodentate N-substituted heteroarylphosphines is described. In general, the ligands are conveniently prepared by selective metallation at the 2-position of the respective N-substituted heterocycle (pyrrole, indole) by using n-butyllithium/tetramethylethylenediamine (TMEDA) followed by quenching with dialkyl- or diarylchlorophosphines. Of the different ligands prepared, the new dialkyl-2-(N-arylindolyl)phosphines (cataCXium P) perform excellently in the palladium-catalyzed amination of aryl and heteroaryl chlorides. Coupling of both activated and deactivated chloroarenes proceeds under mild conditions (room temperature to 60 degrees C). By using optimized conditions remarkable catalyst productivity (total turnover number, TON, up to 8000) and activity (turnover frequency, TOF=14000 h(-1) at 75% conversion) are observed.     

Palladium-catalyzed Hiyama cross-coupling of aryltrifluorosilanes with aryl and heteroaryl chlorides

An efficient, palladium-catalyzed Hiyama cross-coupling reaction of aryltrifluorosilanes with aryl chlorides has been developed. A wide variety of functionalized biaryl derivatives were isolated in good to excellent yields. The scope of this reaction has also been extended to heteroaryl chlorides, affording the corresponding heterobiaryl compounds in high yields.     

Highly efficient monophosphine-based catalyst for the palladium-catalyzed suzuki-miyaura reaction of heteroaryl halides and heteroaryl boronic acids and esters

A highly active and efficient catalyst system derived from a palladium precatalyst and monophosphine ligands 1 or 2 for the Suzuki-Miyaura cross-coupling reaction of heteroaryl boronic acids and esters has been developed. This method allows for the preparation of a wide variety of heterobiaryls in good to excellent yields and displays a high level of activity for the coupling of heteroaryl chlorides as well as hindered aryl and heteroaryl halides. Specific factors that govern the efficacy of the transformation for certain heterocyclic motifs were also investigated.     

New air-stable planar chiral ferrocenyl monophosphine ligands: Suzuki cross-coupling of aryl chlorides and bromides

[reaction: see text] A novel class of planar chiral electron-rich monophosphine ligands has been developed. The modular design allows a short and efficient synthesis of an array of aryl-ferrocenyl derivatives carrying the donating bis(dicyclohexyl)phosphino moiety. These new ligands have successfully been applied in the palladium-catalyzed Suzuki cross-coupling of activated as well as nonactivated aryl chlorides at room temperature. The asymmetric coupling of an aryl bromide and an aryl boronic acid was also tested, giving ees up to 54%.     

CuI-catalyzed suzuki-miyaura and sonogashira cross-coupling reactions using DABCO as ligand

In the presence of TBAB, CuI-catalyzed Suzuki-Miyaura cross-coupling of vinyl halides and aryl halides with arylboronic acids was conducted smoothly to afford the corresponding diarylethenes and polyaryls in moderate to good yields using DABCO (1,4-diazabicyclo[2.2.2]octane) as the ligand. We also found that the inexpensive CuI/DABCO catalytic system was effective for Sonogashira cross-couplings of aryl halides and vinyl halides. A variety of aryl halides and vinyl halides including activated aryl chlorides underwent the coupling with terminal alkynes in moderate to excellent yields.     

Development of the suzuki-miyaura cross-coupling reaction: use of air-stable potassium alkynyltrifluoroborates in aryl alkynylations

The palladium-catalyzed cross-coupling reaction of potassium alkynyltrifluoroborates with aryl halides or triflates proceeds readily with moderate to excellent yields. The potassium alkynyltrifluoroborates are air- and moisture-stable crystalline solids that can be stored indefinitely, which will provide an advantage in applications to combinatorial chemistry. The alkynyl cross-coupling reaction can be effected using 9 mol % of PdCl2(dppf).CH2Cl2 as catalyst in THF or THF-H2O in the presence of Cs2CO3 as the inorganic base. A variety of functional groups are tolerated in both partners.     

Potassium boc-protected secondary aminomethyltrifluoroborates: synthesis and suzuki-miyaura cross-coupling reactions

Seven potassium Boc-protected secondary aminomethyltrifluoroborates were prepared in a standardized two-step process. The Suzuki-Miyaura cross-coupling reaction was studied with this new class of nucleophiles, and a large variety of aryl and hetaryl chlorides provided the desired products in good to excellent yields, thereby allowing easy access to secondary aminomethyl substructures.     

Use of tetrahydropyrimidinium salts for highly efficient palladium-catalyzed cross-coupling reactions of aryl bromides and chlorides

New, sterically demanding 1,3-dialkyl-3,4,5,6-tetrahydropyrimidinium salts (2) as NHC precursors have been synthesized and characterized. These salts, in combination with palladium acetate, provided active catalysts for the cross-coupling of aryl chlorides and bromides under mild conditions. The catalytic system was applied to the Heck, Suzuki and benzaldehyde (Kumada) coupling reactions. Catalyst activity was found to be influenced by the presence of a methoxy group on the ring of the p-position of benzyl substituent of the ligand precursor.     

Highly efficient and reusable supported pd catalysts for Suzuki-Miyaura reactions of aryl chlorides

Syntheses of air- and moisture-stable heterogeneous (tert-butylarylphosphino)polystyrene-supported Pd catalysts and their use for versatile Suzuki-Miyaura reactions of aryl chlorides and arylboronic acids under non-anhydrous conditions are reported. The catalysts are easily recovered by filtration. They can be used many times (more than seven) without showing any loss of activity, and the amount of Pd leached is extremely low (<0.1%).     

An efficient silane-promoted nickel-catalyzed amination of aryl and heteroaryl chlorides

A new silane-promoted nickel-catalyzed amination of aryl chlorides with 0.5 mol % of Ni(acac)2, 1 mol % of 3,5,6,8-tetrabromo-1,10-phenanthroline, and polymethylhydrosiloxane was developed. A broad range of aryl and heteroaryl chlorides can be coupled with secondary amines and anilines to give the desired (het)arylamines in good to excellent yields. The reaction is sensitive to the nature and amount of the silane promoter.     

Polyoxometalate-supported Pd nanoparticles as efficient catalysts for the Mizoroki-Heck cross-coupling reactions in PEG medium

Palladium nanoparticles supported on polyoxometalate as a solid carrier were successfully prepared and evaluated as a heterogeneous nanocatalyst for the Mizoroki-Heck cross-coupling reactions. This supported catalyst was characterized by a set of techniques, including XRD, chemical analysis (ICP-OES), IR spectroscopy, TEM and FE-SEM analyses. Poly (ethylene glycol) was employed as an environmentally friendly solvent for coupling reactions. The various fundamental reaction parameters that influence the efficiency of the reaction and yield of the desired reaction products were optimized. This catalytic system showed good activities and evolve a strategy for achieving five times catalyst and green solvent recyclability without appreciable loss of its activity, thus making this protocol eco-friendly.     

Suzuki-Miyaura cross-coupling reactions of potassium vinyltrifluoroborate with aryl and heteroaryl electrophiles

We have previously reported that the palladium-catalyzed cross-coupling reaction of potassium vinyltrifluoroborate with aryl electrophiles proceeds with good yields. Herein, we describe recent progress in optimizing the reaction, as well as outlining the scope and limitations of the reaction. The cross-coupling reaction can generally be effected using 2 mol % of PdCl2 and 6 mol % of PPh3 as a catalyst system in THF/H2O with Cs2CO3 as a base. Moderate to good yields are obtained in the presence of a variety of functional groups.     

Microwave-assisted Negishi and Kumada cross-coupling reactions of aryl chlorides

Rapid Pd or Ni-catalyzed microwave-accelerated Negishi and Kumada cross-coupling reactions of aryl chlorides in solution and on solid phase are reported.     

Palladium catalyst systems for cross-coupling reactions of aryl chlorides and olefins

A detailed investigation into the influence of phosphines, additives, bases and solvents on the Heck coupling reaction of 4-trifluoromethyl-1-chlorobenzene (2) is presented. It is shown that a number of catalyst systems exist for efficient cross coupling of electron-deficient aryl chlorides with various olefins. Basicity and steric demand of the ligand are two factors which determine the success of the reaction. In addition the phosphine/palladium ratio, the correct type and amount of additive, and finally the use of an appropriate base and solvent are also important. The optimised reaction conditions are applied for the arylation of styrene, 2-ethylhexyl acrylate and N,N-dimethyl acrylic amide with various aryl chlorides.