Palladium‐Catalyzed Heck‐Type Reactions of Allylic Esters with Arylboronic Acids or Potassium Aryltrifluoroborates

A selective and general route to (E)‐1,3‐diaryl‐prop‐1‐enes and (E)‐3‐arylallyl acetates has been developed by palladium‐catalyzed Heck‐type reactions of allylic esters with arylboronic acids or potassium aryltrifluoroborates. The present method selectively proceeds including β‐OAc elimination or β‐H elimination on the basis of the boronic acids. Whereas a variety of allylic esters were reacted with arylboronic acids, palladium(II) acetate [Pd(OAc)₂], tetra(n‐butyl)ammonium chloride [(n‐Bu)₄NCl] and postassium dihydrogen phosphate (KH₂PO₄) to afford the corresponding diarylation products in moderate to good yields, treatment of allylic esters with potassium aryltrifluoroborates furnished the corresponding monoarylation products.     

Synthesis of 3‐Arylindole‐2‐carboxylates via Copper‐Catalyzed Hydroarylation of o‐Nitrophenyl‐Substituted Alkynoates and Subsequent Cadogan Cyclization

A two‐step route to biologically important 3‐arylindole‐2‐carboxylic esters has been successfully established: o‐nitrophenyl‐substituted alkynoates underwent copper‐catalyzed hydroarylation in the presence of commercially available arylboronic acids to afford 3,3‐diarylacrylates, which were then converted to indolecarboxylates via a modified Cadogan cyclization using a molybdenum catalyst and triphenylphosphine.     

Rhodium‐Catalyzed Cross‐Coupling of Alkenyl Halides with Arylboron Compounds

The rhodium(I)‐catalyzed reaction between arylboronic esters and excess 1,2‐dichloroethene selectively afforded (2‐chlorovinyl)arenes. Double arylation yielding 1,2‐diarylethenes was observed when 1,2‐dibromoethene was reacted with 2.5 equivalents of arylboronic acid.

     

Oxidative cyanide-free cyanation on arylboronic acid derivatives using aryl/heteroaryl thiocyanate using novel IL-PdCl4 catalyst under mild condition

An efficient and simple method is reported for the cyanation on arylboronic acid using various simple/indole thiocyanates using a new IL-PdCl₄ catalyst. The cascade process involves a coupling reaction without any additive to give a wide range of cyanide derivatives. Cyanation on various arylboronic acids underwent smoothly affording the corresponding arylnitriles in good to high yields.     

芳基硼酸在有机合成中的应用

芳基硼酸作为一种重要的中间体,在有机合成中的应用相当广泛。Suzuki偶联反应是合成联芳基结构最有效的方法之一,近年许多用于芳基硼酸与各种卤代芳烃偶合的催化剂相继被开发。芳基硼酸与苯酚在Cu(OAc)2和NEt3存在时用于合成二芳基醚,与胺的偶联是合成C-N键的有效方法,与,α-β不饱和体系的1,4-共轭加成反应广泛用于β-取代羰基化合物的合成。反应采用相对无毒而又廉价的普通试剂,反应条件温和,产率高,立体选择性好。综述了芳基硼酸在联芳基合成、二芳基醚合成、芳香胺合成和催化加成反应中的应用。     

The Effect of Arylboronic Acid Treatment of Carbon Fiber on the Mechanical and Tribological Properties of PA66 Composites

PA66 composites filled with surface-treated carbon fiber were prepared by twin-screw extruder in order to study the influence of carbon fiber surface arylboronic acid treatment on the mechanical and tribological behavior of the PA66 composites (CF/PA66). The mechanical property, friction and wear tests of the composites with untreated and treated carbon fiber were performed and the worn surface morphology was analyzed. The results show that the worn surface area of the treated carbon fiber was far smoother than that of the untreated carbon fiber and there formed a bonding adhesion on the carbon fiber surface after treatment. The tensile strength of CF/PA66 composites with surface arylboronic acid treatment was improved. The friction coefficient and wear of arylboronic acid treated CF/PA66 composites were apparently lower than that with untreated carbon fiber. In conclusion, the surface treatment favored the improvement of the higher interface strength and so had good effect on improving the tribological properties of the composites.     

Highly regioselective palladium-catalyzed direct cross-coupling of imidazo[1,2-a]pyridines with arylboronic acids

A highly regioselective method for the palladium-catalyzed direct cross-coupling of imidazo[1,2-a]pyridines with arylboronic acids has been developed by using O₂ as oxidant. This process can be applied to a wide range of imidazo[1,2-a]pyridines and arylboronic acids with excellent C-3-regioselectivity. It provides a new way for developing CC bond-forming processes of multisubstituted imidazo[1,2-a]pyridines, which are common structural motifs in natural products and pharmaceuticals.     

Size-Selective Homocoupling of Arylboronic Acids Mediated by a Copper-Based Metal–Organic-Framework

Copper-based metal–organic-frameworks with open metal sites have received increasing research interest as heterogeneous catalysts for various organic transformations. A copper-based metal organic framework (1) built with L-NO₂ ligand (L-NO₂?=?4,4′-dicarboxy-4″-nitrotriphenylamine) was selected for catalyzing aerobic homocoupling of arylboronic acid toward biaryl products given its structural robustness and 1-D channels lined with rich open metal sites. The experimental results show that MOF (1) exhibits pronounced size selectivity over arylboronic acid molecules, which is only effective for short arylboronic acid molecules (e.g. phenylboronic acid, p-methylphenylboronic acid and p-fluorophenylboronic acid), giving the corresponding biaryl products in good yields. Moreover, MOF (1) also demonstrates a good recyclability which only shows a small decay in the catalytic performance after five repeated runs.

     

合成芳基硼酸及其酯的研究进展

综述了近年来芳基硼酸及其酯的合成研究进展,介绍了各种合成方法的优缺点及其应用前景。     

Synthesis of Benzimidazole‐Substituted Arylboronic Acids via Aerobic Oxidation of 1,2‐Arylenediamines and Formyl‐Substituted Aryl MIDA Boronates using Potassium Iodide as a Catalyst

A highly efficient protocol for the synthesis of benzimidazole‐substituted arylboronic acids was developed via aerobic oxidative cyclization of 1,2‐aryldiamines and formyl‐substituted aryl MIDA (N‐methyliminodiacetic acid) boronates using potassium iodide as a nucleophilic catalyst. Furthermore, a one‐pot protocol for the synthesis of benzimidazole‐substituted arylboronic acids from 1,2‐phenylenediamines and formyl‐substituted arylboronic acids was developed without the isolation of any intermediates. The resulting boronic acids were further subjected to Suzuki–Miyaura coupling reactions without isolation, leading to diaryl‐substituted benzimidazoles with only one separation step.

     

钯催化超临界CO_2中合成四取代烯烃

在超临界CO2中,钯作为催化剂,CsOAc作为碱,用易得的芳基碘、内炔、芳基硼酸三组分偶联高产率地一步合成四取代烯烃。超临界CO2中三组分偶联的最后优化条件是在100℃、PCO2=7.5 MPa下,芳基碘（0.5 mmol）,内炔（0.25 mmol）,芳基硼酸（0.5 mmol）,PdCl2（2 mol%）和CsOAc（1 mmol）反应24 h。超临界二氧化碳作为溶剂优化了这个钯催化体系并且大大的提高了目标产物四取代烯烃的产率。此方法是内炔的全顺式加成,且超临界体系是一个对环境友好的高效体系。     

Aerobic Ligand‐Free Suzuki Coupling Reaction of Aryl Chlorides Catalyzed by In Situ Generated Palladium Nanoparticles at Room Temperature

An aerobic, ligand‐free Suzuki coupling reaction catalyzed by in situ generated palladium nanoparticles in polyethylene glycol with an average molecular weight of 400 Da (PEG‐400) at room temperature has been developed. This catalytic system is a very simple and highly active protocol for the Suzuki coupling of aryl chlorides with arylboronic acids, which proceed smoothly in excellent yields in short times using low catalyst loadings. Control experiments demonstrated that the Suzuki reaction catalyzed by the in situ generated palladium nanoparticles can be carried out much quicker than that using the preprepared particles under the same conditions. The formation of palladium nanoparticles in PEG‐400 was promoted by arylboronic acids.     

Rhodium‐Catalyzed Addition of Boronic Acids to Vinylogous Imines Generated in situ from Sulfonylindoles

The rhodium‐catalyzed addition of arylboronic acids to vinylogous imines generated in situ from sulfonylindoles has been developed. This procedure provided a rapid approach to C‐3 sec‐alkyl‐substituted indoles.     

Electron‐Poor,Fluoro‐Containing Arylboronic Acids as Efficient Coupling Partners for Bis(1,5‐cyclooctadiene)nickel(0)/Tricyclohexylphosphine‐Catalyzed Cross‐Coupling Reactions of Aryl Arenesulfonates

The use of electron‐poor, fluoro‐containing arylboronic acids as general coupling partners for nickel(0)/tricyclohexylphosphine‐catalyzed cross‐coupling of aryl arenesulfonates is described. Electron‐poor fluoro‐containing arylboronic acids were found to react faster than electron‐rich/neutral arylboronic acids, with (4‐methoxyphenyl)(4‐methylbenzenesulfonato‐κO)bis(tricyclohexylphosphine)nickel. Bis(1,5‐cyclooctadiene)nickel(0)/tricyclohexylphosphine, (4‐methoxyphenyl)(4‐methylbenzenesulfonato‐κO)bis(tricyclohexylphosphine)nickel and bis(tricyclohexylphosphine)nickel(II) bromide were all found to be efficient catalysts/catalyst precursors.

     

Mercapto-Functionalized MCM-41 Anchored Palladium(0) Complex as an Efficient Catalyst for the Heterogeneous Suzuki Reaction

Mercapto-functionalized MCM-41 anchored palladium(0) complex is an efficient catalyst for the heterogeneous Suzuki reaction of arylboronic acids with aryl halides. Our system not only solves the basic problems of catalyst separation and recovery but also avoids the use of phosphine ligands.     

Synthesis of Functionalised Phenylalanines Using Rhodium Catalysis in Water

The efficient synthesis of substituted phenylalanine‐type amino acids using a rhodium‐catalysed, conjugate addition of arylboronic acids is described. The reactions are run in water and use a low loading (0.5 mol %) of rhodium catalyst.     

Palladium/Phosphite or Phosphate Catalyzed Oxidative Coupling of Arylboronic Acids with Alkynes to Produce 1,4‐Diaryl‐1,3‐butadienes

The intermolecular oxidative coupling of arylboronic acids with internal alkynes efficiently proceeds in a 2:2 manner in the presence of palladium acetate, a triaryl phosphite or phosphate, and silver carbonate as catalyst, ligand, and oxidant, respectively, to produce the corresponding 1,4‐diaryl‐1,3‐butadiene derivatives.     

Palladium(II)‐Catalyzed One‐Pot Enantioselective Synthesis of Arylglycine Derivatives from Ethyl Glyoxylate,p‐Toluenesulfonyl Isocyanate and Arylboronic Acids

A palladium(II)‐catalyzed, one‐pot enantioselective synthesis of arylglycine derivatives from ethyl glyoxylate, p‐toluenesulfonyl isocyanate and arylboronic acids giving moderate to good yields and enantioselectivity has been developed. This reaction provides a convenient and efficient method for the synthesis of arylglycines.     

Rhodium‐Catalyzed Enantioselective Conjugate Addition of Arylboronic Acids to Dihydronitronaphthalenes

A highly enantioselective (up to 91% ee) rhodium‐catalyzed asymmetric addition of arylboronic acids has been achieved leading to the challenging dihydro‐3‐nitronaphthalenes using one equivalent of phosphoramidite ligand to rhodium catalyst. A concise formal asymmetric synthesis of the dopamine D1 agonist, dihydrexidine was accomplished using the method.     

Highly Efficient and Reusable Polyaniline‐Supported Palladium Catalysts for Open‐Air Oxidative Heck Reactions under Base‐ and Ligand‐Free Conditions

Oxidative Heck reactions of arylboronic acids and alkenes are carried out in the presence of polyaniline‐supported palladium catalysts using air as a co‐oxidant to afford the Heck products with excellent yields and selectivities under base‐ and ligand‐free conditions. The catalyst was recovered by simple filtration and used for several cycles with consistent activity.