Copper-mediated C-H bond arylation of arenes with arylboronic acids

A new copper-mediated cross-coupling of arenes and arylboronic acids is described. Under the influence of Cu(OCOCF 3) 2, the C-H bond arylation of electron-rich arenes with arylboronic acids takes place to afford a range of biaryls in good yields. The reaction is selective for cross-coupling; no homocoupling product arising from arenes or arylboronic acids is detected. Multiple C-H bond arylation is possible with indoles and pyrroles furnishing interesting extended pi-systems.     

无配体、水相中钯催化的卤代芳烃与苯硼酸的Suzuki偶联反应

溴代(碘代)芳烃与苯硼酸在以Li OH为碱、水为反应溶剂、醋酸钯为催化剂、90℃条件下反应24h后,可以较高收率得到二芳基产物。该方法具有收率好,操作方便以及催化体系便宜又简单的优点。     

Homocoupling of arylboronic acids catalyzed by simple gold salts

A range of arylboronic acids undergo a homocoupling reaction in the presence of catalytic amount of gold salts to yield symmetrical biaryls. Alkenylboronic acids, arylboronic esters, and arylborates also participate in the gold-catalyzed homocoupling reaction.     

A base-free, one-pot diazotization/cross-coupling of anilines with arylboronic acids

Pd-catalyzed one-pot diazotization/cross-coupling is realized for the synthesis of biaryls directly from anilines and arylboronic acids.     

Homocoupling of arylboronic acids and potassium aryltrifluoroborates catalyzed by protein-stabilized palladium nanoparticles under air in water

Palladium nanoparticles stabilized primarily within the protein cavity of a highly thermostable Dps protein (DNA binding protein from starved cells) from the thermophilic bacterium Thermosynechoccus elongatus provide an efficient catalyst for the homocoupling of boronic acids and potassium aryltrifluoroborates in water under aerobic phosphine-free conditions. Symmetrical biaryls have been isolated in good to excellent yields. Potassium aryltrifluoroborates give similar or better results than the corresponding arylboronic acids.     

Recyclable and reusable Pd(OAc)2/PPh3/PEG‐2000 system for homocoupling reaction of arylboronic acids under air without base

A stable and efficient Pd(OAc)₂/PPh₃/PEG‐2000 catalytic system for homocoupling of arylboronic acids has been developed. In the presence of Pd(OAc)₂ and PPh₃, the homocoupling reaction of arylboronic acids was carried out smoothly in PEG‐2000 at 70 °C under air without base to afford a variety of symmetric biaryls in good to excellent yields. The isolation of the products was readily performed by extraction with diethyl ether, and the Pd(OAc)₂/PPh₃/PEG‐2000 system could be easily recycled and reused six times without significant loss of catalytic activity. Copyright © 2014 John Wiley & Sons, Ltd.     

Ni-catalyzed cross-coupling reaction of aryl chlorides with arylboronic acids in IPA without using a reducing reagent

The coupling reaction of aryl chlorides with arylboronic acids was successfully performed in isopropanol (IPA) by using [NiCl(Ph₂PCH₂CH₂OH)₂(H₂O)]Cl (5), a cationic Ni(II)-complex, as a precatalyst in the absence of a reducing agent. The coupling reaction proceeded smoothly under mild conditions to provide biaryls in satisfactory to excellent yields, and formation of the undesired dechlorination products of aryl chlorides was completely prevented.     

Indolylbenzimidazole‐based ligands catalyze the coupling of arylboronic acids with aryl halides

A novel class of compounds bearing indole and benzimidazole rings was designed and easily synthesized from 2‐indolecarboxylic acid and o‐phenylenediamine. The catalytic system derived from a 2‐indolylbenzimidazole‐based ligand and Pd(OAc)₂ in situ could lead to complete conversion of aryl bromides at 0.5 mol% Pd loading under mild reaction conditions. In the presence of a catalyst, sterically hindered biaryls were selectively generated in excellent yields by adjusting reaction parameters through the coupling of arylboronic acids with aryl halides. The efficiency of this reaction was demonstrated by its compatibility with various functional groups.     

Electrooxidative homo-coupling of arylboronic acids catalyzed by electrogenerated cationic palladium catalysts

An electrochemical method for generating cationic palladium complexes was integrated into an electrooxidative homo-coupling of arylboronic acids. In the presence of a catalytic amount of TEMPO, the homo-coupling reaction proceeded efficiently under argon to afford symmetric biaryls.     

Electrophilic ipso-iodination of silylated arylboronic acids

Silylated functionalized arylboronic acids were converted into corresponding iodinated arylboronic acids in good yields via the electrophilic ipso-desilylation effected with iodine chloride in refluxing CHCl₃. Disilylated arylboronic acids were susceptible to diiodination. In addition, the structural characterization and reactivity of a novel sterically hindered ortho-silylated diarylborinic ester were reported. The potential of selected iodinated phenylboronic acids as monomers for the Suzuki-Miyaura cross-coupling polymerization was demonstrated.     

Synthetic connections to the aromatic directed metalationreaction. Unsymmetrical biaryls by palladium-catalyzed cross coupling of directed metalation-derived arylboronic acids with aryl halides

The arylboronic acids 2 and 4 derived by directed ortho metalation of benzamides and carbamates, undergo an efficient palladium-catalyzed cross coupling reaction with a variety of aryl halides to yield unsymmetrical biaryls and heterobiaryls (Table).     

Oxidative homocoupling of arylboronic acids catalyzed by a 4‐aminoantipyrine–Pd(II)complex

A one‐step synthesis of symmetric biaryls is reported under very mild conditions via the homocoupling reaction of substituted arylboronic acids using an air‐ and moisture‐stable 4‐aminoantipyrine–Pd(II) complex as catalyst. The reaction is conducted at a low catalyst loading of 0.1 mol% at room temperature in methanol in the presence of K₂CO₃ as the base and KMnO₄ as the oxidant. The catalytic methodology is shown to be compatible with diverse functional groups and affords the desired biphenyls in good to excellent yields. Copyright © 2015 John Wiley & Sons, Ltd.     

A highly efficient and recyclable NiCl2(dppp)/PEG-400 system for Suzuki-Miyaura reaction of aryl chlorides with arylboronic acids

Abstract

NiCl₂(dppp) in PEG-400 is shown to be a highly efficient catalyst for Suzuki-Miyaura coupling of aryl chlorides with arylboronic acids. The reaction could be conducted at 100?°C using K₃PO₄ as base, yielding a variety of biaryls in good to excellent yields. The isolation of the products was readily performed by extraction with petroleum ether and NiCl₂(dppp)/PEG-400 system could be easily recycled and reused up to five times without significant loss of activity. Our system not only avoids the use of easily volatile and toxic dioxane or toluene as a solvent but also solves the basic problem of nickel catalyst reuse.     

Base-free Pd-MOF catalyzed the Suzuki-Miyaura cross-coupling reaction of arenediazonium tetrafluoroborate salts with arylboronic acids

A convenient and environmental benign synthesis of biaryls has been demonstrated by a straightforward reaction catalyzed by the palladium-containing metal-organic framework (Pd-MOF) [Pd (2-pymo)₂]_n (2-pymo = 2-pyrimidinolate). A series of functionalized biaryl derivatives have been synthesized in good to excellent yields by the Suzuki-miyaura cross-couplings of sustainable arenediazonium salts with a variety of arylboronic acids and the reactions were catalyzed by the Pd-MOF using methanol as a benign solvent. Those base- and additive-free catalytic reactions proceeded smoothly under non-anhydrous and non-degassed condition. Such transformation avoided high reaction temperature, tolerated many functional groups and presented a wide substrate scope. The catalyst could be recovered by filtration and reused for four successive cycles before collapse of the MOF structure.     

Mechanism of the palladium-catalyzed homocoupling of arylboronic acids: key involvement of a palladium peroxo complex

The mechanism of the palladium-catalyzed homocoupling of arylboronic acids ArB(OH)(2) (Ar = 4-Z-C(6)H(4) with Z = MeO, H, CN) in the presence of dioxygen, leading to symmetrical biaryls, has been fully elucidated. The peroxo complex (eta(2)-O(2))PdL(2) (L = PPh(3)), generated in the reaction of dioxygen with the Pd(0) catalyst, was found to play a crucial role. Indeed, it reacts with the arylboronic acid to generate an adduct (coordination of one oxygen atom of the peroxo complex to the oxophilic boron atom of the arylboronic acid) characterized by (31)P NMR spectroscopy and ab initio calculations. This adduct reacts with a second molecule of arylboronic acid to generate trans-ArPd(OH)L(2) complexes. A transmetalation by the arylboronic acid gives trans-ArPdArL(2) complexes. The biaryl is then released in a reductive elimination. This reaction is at the origin of the formation of biaryls as byproducts in palladium-catalyzed Suzuki-Miyaura reactions when they are not conducted under oxygen-free atmosphere.     

Base-free oxidative homocoupling of arylboronic esters

Base-free oxidative homocoupling reaction of arylboronic esters has been found to proceed using a catalytic amount of a palladium-1,3-bis(diphenylphosphino)propane (DPPP) complex under an oxygen atmosphere, affording a variety of biaryls in modest to excellent yields. Even arylboronic esters bearing a base-sensitive functional group are applicable to the reaction.     

Efficient palladium-catalyzed Suzuki-Miyaura coupling of aryl chlorides with arylboronic acids using benzoferrocenyl phosphines as supporting ligands

Four monodentate benzoferrocenyl phosphines were studied as supporting ligands in palladium-catalyzed Suzuki-Miyaura coupling of aryl chlorides with arylboronic acids. Of these ligands, the more electron-rich and steric demanding benzoferrocenyl dicyclohexyl phosphine was found highly effective for the reaction followed by the benzoferrocenyl diisopropyl phosphine. The corresponding diethyl and diphenyl phosphines are much less active. When the dicyclohexyl phosphine was used, both electron-rich and electron-poor aryl chlorides were coupled with arylboronic acids within 1 h giving good to excellent yields. Chloro-substituted pyridines were also found highly reactive under these conditions giving excellent yields of biaryl products. Sterically hindered biaryls can also be prepared using the dicyclohexyl phosphine as ligand.     

Suzuki-Miyaura cross-couplings of arenediazonium tetrafluoroborate salts with arylboronic acids catalyzed by aluminium hydroxide-supported palladium nanoparticles

Suzuki-Miyaura cross-couplings of arenediazonium salts with arylboronic acids catalyzed by highly active aluminium hydroxide-supported palladium nanoparticles catalyst have been investigated for the first time. The reactions are performed at 25 °C in MeOH without any base and ligand to afford biaryls in good to excellent yields under non-anhydrous and non-degassed conditions.     

Manganese(III) acetate-mediated synthesis of biaryls under microwave irradiation

Manganese(III) acetate (Mn(OAc)₃)-mediated synthesis of biaryls and heterobiaryls starting from arylboronic acid was developed under microwave irradiation in high yields. Microwaves were also used for the synthesis of Mn(OAc)₃ from KMnO₄ and acetic acid. Additional irradiation of this in situ generated Mn(OAc)₃ with arylboronic acids, which in turn furnished the biaryls in high yields in a one pot reaction. This is superior from the point of view of yield, short reaction time, sensitive functional group toleration, and more environmentally friendly than the reported methods with a minimum amount of benzene and thiophene as a reagent but not as a solvent.     

Tetrasubstituted olefin synthesis via Pd-catalyzed addition of arylboronic acids to internal alkynes using O2 as an oxidant

The Pd(II)-catalyzed reaction of arylboronic acids and internal alkynes provides a convenient route to a wide variety of tetrasubstituted olefins. The reaction is conducted in DMSO using molecular O2 as an oxidant in the absence of any base. The reaction involves the cis addition of two aryl groups from the arylboronic acid to opposite ends of the triple bond of the internal alkyne. The synthesis tolerates a wide variety of functional groups, including alcohol, aldehyde, ester, TMS, and acetal groups. Electron-rich dialkylacetylenes, such as 4-octyne, provide highly substituted 1,3-dienes in moderate yields. The very mild O2/DMSO conditions also afford good to excellent yields of biaryls by the homocoupling of arylboronic acids.