Aryl Coupling Research Articles

ChemInform Abstract: Palladium‐Catalyzed Cross‐Couplings of Functionalized 2‐Bromobenzofurans for Atom‐Economic Synthesis of 2‐Arylbenzofurans Using Triarylbismuth Reagents.

AbstractThe bismuth agents undergo three aryl couplings as multi‐coupling organometallic nucleophiles and the reaction is complete in a short time.

ChemInform Abstract: Efficient Recyclable CuI‐Nanoparticle‐Catalyzed S‐Arylation of Thiols with Aryl Halides on Water under Mild Conditions.

AbstractThe title procedure avoids the undesired formation of disulfides.

N-Heterocyclic Carbene–Palladium(II)–1-Methylimidazole Complex-Catalyzed Suzuki–Miyaura Coupling of Aryl Sulfonates with Arylboronic Acids

A well-defined NHC-Pd(II)-Im complex 1 was found to be an effective catalyst for the Suzuki-Miyaura coupling of aryl sulfonates including tosylates and phenylsulfonates with arylboronic acids, giving the desired coupling products in good to high yields. Acceptable yields can also be achieved even by using the less reactive mesylates as the substrates. It is worthy of noting here that this is the first example of NHC-Pd(II) complex-catalyzed Suzuki-Miyaura coupling of aryl sulfonates with arylboronic acids, enriching an inexpensive, convenient, and alternative method for the synthesis of biaryl compounds.

Synthesis, DNA binding and antileishmanial activity of low molecular weight bis-arylimidamides

The effects of reducing the molecular weight of the antileishmanial compound DB766 on DNA binding affinity, antileishmanial activity and cytotoxicity are reported. The bis-arylimidamides were prepared by the coupling of aryl S-(2-naphthylmethyl)thioimidates with the corresponding amines. Specifically, we have prepared new series of bis-arylimidamides which include 3a, 3b, 6, 9a, 9b, 9c, 13, and 18. Three compounds 9a, 9c, and 18 bind to DNA with similar or moderately lower affinity to that of DB766, the rest of these compounds either show quite weak binding or no binding at all to DNA. Compounds 9a, 9c, and 13 were the most active against Leishmania amazonensis showing IC50 values of less than 1 μM, so they were screened against intracellular Leishmania donovani, showing outstanding activity with IC50 values of 25–79 nM. Despite exhibiting little in vitro cytotoxicity these three compounds were quite toxic to mice.

Pd‐Catalyzed Threefold Arylation of Baylis–Hillman Bromides and Acetates with Triarylbismuth Reagents

AbstractFunctionalized alkyl 2‐benzylacrylates and 2‐benzylacrylonitriles were synthesized by means of atom‐economic cross‐couplings of Baylis–Hillman bromides or acetates with BiAr3 under palladium‐catalyzed conditions. These reactions, involving threefold aryl couplings using BiAr3 reagents with bromides and acetates, are fast and are completed in 1–2 h with high product yields.

Synthesis of Geodesic Polynuclear Arenes and Fullerenes by Intramolecular Aryl–Aryl Coupling

Bending over backwards to build buckybowls and -balls? For the last two decades, flash vacuum pyrolysis of chloro- and bromoarenes has been the method of choice for intramolecular aryl-aryl couplings that afford geodesic polynuclear arenes ("buckybowls") including fullerene C(60). Recently, even fluoroarenes were subjected under relatively mild conditions to intramolecular C(Ar)-C(Ar) couplings by combining the cleavage of C(Ar)-F with the formation of very strong Si-F or Al-F bonds (see picture; green C, white H).

Total Synthesis of (+)‐Davidiin

Quite strained: The total synthesis of (+)-davidiin, an ellagitannin with more substituents in axial than in equatorial positions, requires a conformational lock of the glucose, induced by steric repulsion between adjacent bulky silyloxy groups. This conformational lock played a pivotal role in 1) the β-selective formation of the glycosyl ester at the anomeric position, 2) the formation of the 1,6-HHDP bridge, and 3) the complete control of axial chirality in the aryl–aryl coupling.

ChemInform Abstract: Microwave‐Enhanced Triton B Catalyzed Suzuki Coupling Reaction.

AbstractAn efficient method for the Suzuki coupling of aryl and heteroaryl halides with aryl and heteroaryl boronic acids is presented.

Oxidative Trifluoromethylthiolations of Aryl Boronic Acids Using a Copper/O2‐Based Protocol

All you need is air: A new protocol has been developed which can mediate the coupling of aryl and vinyl boronic acids at room temperature in high yields (see scheme, dtbpy=4,4′-di-tert-butyl-2,2′-bipyridine). The reactions take place using simple copper(II) salts under aerobic conditions and do not require the use of expensive silver oxidants. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

ChemInform Abstract: Aminoborylation/Suzuki—Miyaura Tandem Cross Coupling of Aryl Iodides as Efficient and Selective Synthesis of Unsymmetrical Biaryls.

AbstractSequential borylation of a first aryl iodide (I) using a dialkylaminoborane followed by a Suzuki—Miyaura cross coupling of second aryl iodide (II) affords unsymmetrical biaryls, in an efficient and practical manner.

Cyclopalladated ferrocenylimine as an efficient catalyst for the syntheses of diarylmethane derivatives

The cyclopalladated ferrocenylimine adducts Ia, Ib, Ic were evaluated in the Suzuki cross‐coupling reaction of benzyl halides with arylboronic acids. The tricyclohexylphosphine adduct Ia exhibited highly catalytic activity for the coupling of aryl and heteroaryl boronic acids containing various functional groups with benzylic bromides and chlorides (up to 99% yield), furnishing diarylmethane derivatives with low catalyst loading (1 mol%). It is worth noting that catalyst Ia can be reused eight times without losing its catalytic activity. Copyright © 2012 John Wiley & Sons, Ltd.

Preparation and Characterization of Aryl or Heteroaryl(3-indolyl)methylium o-Benzenedisulfonimides

An initial study has been accomplished into the synthetic feasibility of the preparation of diarylcarbenium salt via the direct coupling of aryl (or heteroaryl) aldehydes and arenes (or heteroaryl analogues) in the presence of a strong organic Brønsted acid. A number of stabilized aryl or heteroaryl(3-indolyl)carbenium ions, never previously prepared in the solid state, have been isolated in excellent yields as highly stable o-benzenedisulfonimide salts and have been fully characterized. Their purity has been proven by spectroscopic methods and chemical reduction with NaBH(4). An X-ray crystal structure analysis has been performed on one of the products: an azafulvenium species was shown to be the exclusive structure in the solid state.

Facile Bucky‐Bowl Synthesis by Regiospecific Cove‐Region Closure by HF Elimination

Building bowls: An effective intramolecular aryl–aryl coupling is the key step in rational fullerene synthesis and in synthesis of extended buckybowl structures. Such a process can be embodied very efficiently through quantitative HF elimination on active Al2O3. The process is characterized by an unprecedentedly high chemoselectivity and regiospecificity.

Palladium-catalyzed cross-couplings of functionalized 2-bromobenzofurans for atom-economic synthesis of 2-arylbenzofurans using triarylbismuth reagents

The palladium catalyzed, atom-economic synthesis of various functionalized 2-arylbenzofurans was achieved through cross-coupling reaction of 2-bromobenzofurans with triarylbismuth reagents. The palladium catalytic protocol is very efficient to furnish various cross-coupled functionalized 2-arylbenzofurnas in high yields using triarylbismuth reagents with three aryl couplings as multi-coupling organometallic nucleophiles in one-pot operation. All the coupling reactions were completed in 1h short reaction time involving three couplings from triarylbismuths under heating condition.

ChemInform Abstract: A Homogeneous, Recyclable Polymer Support for Rh(I)‐Catalyzed C—C Bond Formation.

AbstractThe catalyst efficiently promotes the coupling of aryl‐ and alkenylboronic acids with enones, aldehydes, aldimines, and internal alkynes as well as the hydroformylation of alkenes and the addition of enones to terminal alkynes.

Unusual redox play of Mo(V/IV) during oxidative aryl–aryl coupling

The oxidative treatment of a suitable 1,3-diarylpropene precursor by MoCl5 causes a series of redox steps yielding a dimer of dibenzo[a,c]cycloheptene. After the oxidative aryl–aryl bond formation, a C,H activation occurs providing a tropylium intermediate. Upon aqueous workup the metal waste acts as reductive media generating the dimer in an almost quantitative manner. The oxidative generation of the tropylium species as well as the subsequent redox play by the metal waste is unique and unprecedented. The dimeric compound can be oxidatively cleaved and subsequently decarboxylated providing the key intermediate of a previous synthesis of metasequirin-B derivatives.

Nucleophilic Substitutions and Radical Reactions of Phenylazocarboxylates

tert-Butyl phenylazocarboxylates are versatile building blocks for synthetic organic chemistry. Nucleophilic substitutions of the benzene ring proceed with aromatic amines and alcohols under mild conditions. The attack of aliphatic amines may be directed to the aromatic core as well as to the carbonyl unit leading to azocarboxamides. The benzene ring can further be modified through radical reactions, in which the tert-butyloxycarbonylazo group enables the generation of aryl radicals at either elevated temperatures or under acidic conditions. Radical reactions include oxygenation, halogenation, carbohalogenation, carbohydroxylation, and aryl-aryl coupling.

Few unexpected results from a Suzuki–Miyaura reaction

In the course of the synthesis of original anti-infectious compounds we focused on the palladium-catalyzed Suzuki–Miyaura aryl–aryl coupling reaction between 2-(3-ethoxy-5-iodo-1H-pyrazol-1-yl)pyridine and phenylboronic acid. A study of the reaction products obtained under different conditions (various ligands and solvents), not only provided us with insights to optimize this reaction but also with few side compounds, resulting from CH activation, along with the unexpected bis(3-ethoxy-1-(pyridin-2-yl)-1H-pyrazol-5-yl)palladium. Stochiometric experiments with this remarkably stable biscyclopalladated reagent and phenylhalides pointed out the occurrence of aryl–aryl coupling, possibly via palladium IV intermediates.

Efficient recyclable CuI-nanoparticle-catalyzed S-arylation of thiols with aryl halides on water under mild conditions

CuI nanoparticles efficiently catalyzed the C-S cross coupling of aryl and alkyl thiols with aryl halides in the absence of ligands on water under mild conditions. A wide range of diaryl sulfides and aryl alkyl sulfides are synthesized in good to excellent yields utilizing this protocol. This procedure is particularly noteworthy given its mild conditions, avoiding the undesired formation of disulfides through oxidation of thiols. The recovery and successful reutilization of the catalyst is described. Furthermore, the directed synthesis of bisarylated product is presented.

ChemInform Abstract: Recent Advances in Sonogashira Reactions

AbstractReview: 352 refs.