Efficient use of a surfactant for copper-catalyzed coupling reaction of arylboronic acids with imidazoles in water

Copper-catalyzed oxidative coupling of arylboronic acids with imidazoles in water was realized by using an amphiphilic surfactant. By choosing an appropriate surfactant, reactions of a variety of arylboronic acids proceeded smoothly under mild and base-free conditions, providing an efficient, practical, and greener method for the synthesis of N-arylimidazoles.     

Palladium-catalyzed cross-coupling reactions of 2-diazonaphthoquinones with arylboronic acids

Palladium-catalyzed cross-coupling reactions of 2-diazonaphthoquinones and arylboronic acids proceeded by the treatment with Pd(OAc)₂ in acetic acid to afford 2-aryl-1-naphthols.     

In situ generated cationic Pd(II)/bipyridine-catalyzed addition of arylboronic acids to N-sulfonyl-arylaldimines

An in situ generated cationic Pd(II)/bipyridine-catalyzed nucleophilic addition of arylboronic acids to N-sulfonyl arylaldimines was developed and optimized, and the reaction was proceeded highly efficiently and conveniently in CH₃NO₂. A series of arylboronic acids and N-sulfonyl arylaldimines were surveyed, and 12 of 13 examples gave 90～96% yields.     

低温Suzuki反应合成联苯及三联苯化合物

发展了一个低温下无配体钯催化溴代芳烃与芳基硼酸的Suzuki反应体系。该体系以醋酸钯为催化剂,无水碳酸钾为碱,乙醇水溶液为溶剂,无需加入任何配体,在0oC下即可高效催化溴代芳烃与芳基硼酸的Suzuki反应;反应的底物容忍性好,产品分离收率最高达97%。以溴代芳基N-甲基亚氨基二乙酸硼酸酯为砌块分子,通过调控反应温度,实现了砌块分子选择性Suzuki反应,从而一锅合成了不对称三联苯化合物,产品收率最高为81%。     

Synthesis of Terphenyl Derivatives by Pd‐Catalyzed Suzuki‐Miyaura Reaction of Dibromobenzene Using 2N2O‐Salen as a Ligand in Aqueous Solution

A simple and efficient catalytic system for Na₂PdCl₄ catalyzing the Suzuki‐Miyaura reaction of dibromobenzene and arylboronic acid has been developed by using 2N2O‐salen as a ligand in H₂O/EtOH (V:V=4:1) at 100°C. Using this method, the reactions of substrates containing sterically demanding ortho substituents (e.g. dibromobenzene and/or arylboronic acids) proceeded efficiently, with the corresponding terphenyl derivatives being produced in moderate to excellent yields. Furthermore, this method offers interesting features for the multi‐gram scale synthesis of terphenyl compound.     

Supported Palladium-Catalyzed Carbonylative Synthesis of Diaryl Ketones from Aryl Bromides and Arylboronic Acids

A palladium supported on graphitic carbon nitride (Pd/g-C₃N₄) catalyzed carbonylative reaction of aryl bromides and arylboronic acids by has been developed for the construction of diaryl ketones. Using benzene-1,3,5-triyl triformate (TFBen) as the CO source, the reaction proceeded well to give various diaryl ketones in moderate to good yields.     

Efficient, protection-free Suzuki-Miyaura synthesis of ortho-biphenyltetrazoles

We describe an efficient protocol for the Suzuki-Miyaura synthesis of ortho-biphenyltetrazoles from non-protected 2-bromophenyltetrazole and arylboronic acids. The optimised conditions were achieved using [1,1′-bis(diphenylphosphino)ferrocene]dichloropalladium(II) as catalyst and Na₂CO₃ as base. A panel of structurally diverse arylboronic acids was used to demonstrate the scope of the coupling procedure.     

Synthesis of 1,5-disubstituted tetrazoles via Suzuki-Miyaura cross-coupling of 5-chloro-1-phenyltetrazole

Suzuki-Miyaura coupling reactions of 5-chloro-1-phenyl-tetrazole with various functionalized arylboronic acids were investigated. In the presence of catalytic amounts of SPhos/Pd(OAc)₂ or RuPhos/Pd(OAc)₂, the reaction proceeded smoothly to afford 1,5-diaryltetrazoles in good to excellent yields.     

Palladium‐Catalyzed Asymmetric Arylation of Trifluoromethylated/Perfluoroalkylated 2‐Quinazolinones with High Enantioselectivity

Asymmetric arylation of 4‐fluoroalkyl‐2‐quinazolinone derivatives with arylboronic acids proceeded smoothly in the presence of a cationic palladium catalyst (1 mol %) coordinated with a chiral phosphinooxazoline (phox) ligand to create the corresponding fluorine‐containing arylated dihydroquinazolinones in high yields and with greater than 99 % ee.     

Rhodium-catalyzed regioselective cross-coupling of styrene oxides with arylboronic acids in aqueous γ-valerolactone

A simple and regioselective cross-coupling of styrene oxides with arylboronic acids in the presence of Rh(PPh₃)₃Cl in biomass-derived γ-valerolactone has been developed. The reactions proceeded smoothly to give 1,2-diaryl ethanols as the predominant products in moderate to good yields.     

Air-stable Pd(II) catalysts with cryptand-22 ligand for convenient and efficient Suzuki cross-coupling reactions

Air-stable Pd(II) catalysts with cryptand-22 ligand was easily handled in atm air at room temperature for Suzuki cross-coupling reactions of aryl bromides with arylboronic acids both containing electron-withdrawing and electron-donating groups. Generally, reactions proceeded fast to completion in 2 h to give high product yields. Our Pd(OAc)₂/cryptand-22 catalyst is unique, since the reaction solution remained yellow during reaction period and air-stable without formation of Pd black as usually observed for ordinary simple amine ligands.     

A simple method to prepare single isomer tetrasubstituted olefins by successive Suzuki–Miyaura cross-couplings of E-β-chloro-α-iodo-α,β-unsaturated esters

A convenient method of synthesizing tetrasubstituted olefins as single isomers is described. E-β-Chloro-α-iodo-α,β-unsaturated esters are first converted into the corresponding E-β-chloro-α,β-unsaturated esters using Suzuki–Miyaura coupling reactions with arylboronic acids and alkenylboronic acids. These transformations gave complete selectivity, and proceeded with substitution at the more activated α-iodide position. These compounds, isolated as single isomers, were then transformed into tetrasubstituted olefins by Suzuki–Miyaura couplings with arylboronic acids, alkenylboronic acids, and alkyl boranes to afford the corresponding tetrasubstituted olefins as single isomers. During this coupling process, it was discovered that the use of small ligands, such as PMe₃ or PEt₃, was critical for efficient coupling. The stereochemistry and regiochemistry of the products were unequivocally established using NMR methods.     

Pd-catalyzed C-C bond-forming reactions of thymidine mesitylene sulfonate

Facile synthesis of C-4 aryl pyrimidinone nucleoside analogues from an easily prepared O4-arylsulfonate derivative of thymidine is reported. Two O4-arylsulfonylthymidine precursors, (4-methylphenyl)sulfonyl and (2,4,6-trimethylphenyl)sulfonyl, were prepared and analyzed for their stabilities. Of the two, the latter possessed suitable stability as well as reactivity for Pd-catalyzed C-C bond-forming reactions with a variety of arylboronic acids. These reactions at the C-4 position are nontrivial in comparison with similar reactions at the C-5 position of pyrimidine nucleosides, with hydrolysis of the arylsulfonate precursor being a competing reaction in some cases. There are pronounced solvent influences in these reactions, but successful reactions can be attained by careful control of conditions. Many reactions proceeded efficiently at room temperature, and electron-deficient arylboronic acids can also be cross-coupled under suitable conditions. Desilylation of these products was also nontrivial, and various conditions were tested. Finally, antiviral screening was performed with the C-4 aryl pyrimidinone nucleoside analogues, but none possessed any interesting activity. The study represents the first successful synthesis of C-4 aryl pyrimidinone nucleoside analogues by cross-coupling of arylboronic acids with an arylsulfonate derived from a pyrimidine nucleoside, as well as antiviral testing of this new class of compounds.     

Efficient palladium(II) catalysis under air. Base-free oxidative heck reactions at room temperature or with microwave heating

Scope and limitations of the base-free oxidative Heck reaction with arylboronic acids have been explored. Under our conditions, the dmphen-palladium(II)-catalyzed arylation proceeded with air or p-benzoquinone as reoxidants of palladium(0). We found that ambient temperature and mild aerobic conditions allow for the use of substrates sensitive to palladium(II)-catalyzed oxidation. Oxidative Heck couplings, employing different arylboronic acids, were smoothly and regioselectively conducted with both electron-rich and electron-poor olefins, providing high yields even with disubstituted butyl methacrylate, sensitive acrolein, and a vinylboronate ester. Controlled microwave processing was used to reduce reaction times from hours to minutes both in small scale and in 50 mmol scale batch processes.     

Polymer-supported N-heterocyclic carbene-rhodium complex catalyst for the addition of arylboronic acids to aldehydes

A novel polymer-supported N-heterocylic carbene (NHC)-rhodium complex was prepared from chloromethyl polystyrene (CM PS) resin using a simple procedure. This polymer-supported NHC-rhodium complex was used as a catalyst for the addition of arylboronic acids to aldehydes affording arylmethanols in excellent yields.     

Facile Access to Fluoromethylated Arenes by Nickel‐Catalyzed Cross‐Coupling between Arylboronic Acids and Fluoromethyl Bromide

The nickel‐catalyzed fluoromethylation of arylboronic acids was achieved with the industrial raw material fluoromethyl bromide (CH₂FBr) as the coupling partner. The reaction proceeded under mild reaction conditions with high efficiency; it features the use of a low‐cost nickel catalyst, synthetic simplicity, and excellent functional‐group compatibility, and provides facile access to fluoromethylated biologically relevant molecules. Preliminary mechanistic studies showed that a single‐electron‐transfer (SET) pathway is involved in the catalytic cycle.     

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.     

Planar chiral imidazolium salts based on [2.2]paracyclophane in the asymmetric rhodium-catalyzed 1,2-addition of arylboronic acids to aldehydes

A series of planar chiral imidazolium salts derived from [2.2]paracyclophane have been synthesized and characterized. By using these imidazolium salts as carbene precursors, the Rh-catalyzed 1,2-addition of arylboronic acids to aldehydes proceeded readily with low catalyst loadings (0.03–0.3 mol %) and gave a variety of chiral diarylmethanols in excellent yields and moderate enantioselectivities.     

Optimized Palladium(0)‐catalyzed Suzuki Cross‐coupling Reaction of Polystyrene‐supported Selenenyl Flavanones: A Convenient Preparation of Biaryl‐chromen‐4‐one

Application of the Suzuki cross‐coupling reaction for efficient synthesis of diverse substituted biaryl‐chromen‐4‐ones using an optimized palladium(0) catalyst system is reported. The coupling of arylboronic acids with the resin‐bound bromoflavanones which were prepared by organoselenium‐induced regioselective intramolecular cyclization of bromo‐2‐hydroxylchalcones proceeded smoothly. Biaryl‐chromen‐4‐ones were synthesized by subsequent selenoxide syn‐elimination in good total yields.     

Enantioselective rh-catalyzed arylation of N-tosylarylimines with arylboronic acids

The asymmetric arylation of N-tosylarylimines with arylboronic acids was realized by using rhodium/(S)-ShiP as catalyst. The reaction proceeded in aqueous toluene to give diarylmethylamines in good yields with up to 96% ee. [reaction: see text]