Unsymmetrical Biaryls Research Articles

One‐Pot Preparation of Unsymmetrical Biaryls via Suzuki Cross‐Coupling Reaction of Aryl Halide Using Phase‐Transfer Catalyst in a Biphasic Solvent System.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

BF3×Et2O‐Catalyzed Direct Carbon—Carbon Bond Formation of α‐EWG Ketene‐(S,S)‐Acetals and Alcohols and Synthesis of Unsymmetrical Biaryls.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Biaryl Synthesis via Pd-Catalyzed Decarboxylative Coupling of Aromatic Carboxylates with Aryl Halides

A new strategy for the regiospecific construction of unsymmetrical biaryls is presented, in which easily available salts of carboxylic acids are decarboxylated in situ to give arylmetal species that serve as the nucleophilic component in a catalytic cross-coupling reaction with aryl halides. The catalyst system consists of a copper phenanthroline complex that mediates the extrusion of CO2 from aromatic carboxylates to generate arylcopper species, and a palladium complex that catalyzes the cross-coupling of these intermediates with aryl halides. This bimetallic system allows the direct coupling of various aryl, heteroaryl, or vinyl carboxylic acids with aryl or heteroaryl iodides, bromides, or chlorides at 160 degrees C in the presence of a mild base such as potassium carbonate. The present scope and potential economic impact of the reaction are demonstrated by the synthesis of 42 biaryls, some of which are of substantial industrial relevance. Remaining challenges and future perspectives of the new transformation are discussed.

One‐Pot Preparation of Unsymmetrical Biaryls via Suzuki Cross‐Coupling Reaction of Aryl Halide using Phase‐Transfer Catalyst in a Biphasic Solvent System

A one‐pot synthetic method of unsymmetrical biaryls was developed via the Suzuki cross‐coupling reaction of aryl halide using a phase‐transfer catalyst in a biphasic solvent system.

Pd‐Catalyzed Synthesis of Biphenyls with Methylthio Group

The synthesis of unsymmetrical biaryls with a methylthio group is achieved using the air‐stable palladium–phosphinous acid complexes, [(t‐Bu)2P(OH)]2 PdCl2 (POPd), as the catalyst. A great variety of substituted bromobenzenes having electron‐withdrawing and electron‐donating functional groups in para and meta positions have been successfully coupled with 3‐methylthiophenylboronic acid.

Phosphine oxides as stabilizing ligands for the palladium-catalyzed cross-coupling of potassium aryldimethylsilanolates

The palladium-catalyzed cross-coupling reaction of potassium (4-methoxyphenyl)dimethylsilanolate (K + 1 −) with aryl bromides has been demonstrated using triphenylphosphine oxide as a stabilizing ligand. Unsymmetrical biaryls can be prepared from a variety of aryl bromides in good yield with short reaction times. Qualitative kinetic studies compared effects of different phosphine oxides on the rate of cross-coupling and established the beneficial effect of these ligands in the reaction of electron-rich arylsilanolates. The improved yield and reproducibility of the cross-coupling of several bromides was demonstrated by direct comparison of reactions performed with and without triphenylphosphine oxide under non-rigorous exclusion of oxygen.

A Facile Synthesis of Unsymmetrical Biaryls via Coupling Reaction of Aryl Halides with Sodium Tetraphenylborate Catalyzed by MCM‐41‐Supported Thioether Palladium(0) Complex.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

BF3·Et2O-Catalyzed Direct Carbon−Carbon Bond Formation of α-EWG Ketene-(S,S)-Acetals and Alcohols and Synthesis of Unsymmetrical Biaryls

A highly efficient BF3.OEt2-catalyzed formal dehydration C-C coupling reaction between readily available alpha-EWG ketene-(S,S)-acetals and various alcohols via direct substitution of the hydroxy group in alcohols has been developed. On the basis of this C-C coupling reaction, a series of alkylated alpha-EWG ketene-(S,S)-acetals and functionalized 1,4-pentanedienes were prepared in high to excellent yields and the unsymmetrical biaryls were synthesized in good yields from the generated 1,4-pentanedienes and nitroalkanes through a one-pot annulation-aromatization process.

Intermolecular Cross-Coupling of Simple Arenes via C−H Activation by Tuning Concentrations of Arenes and TFA

Formation of unsymmetrical biaryls from simple arenes has been achieved successfully in a catalytic system of Pd(OAc)2/CF3CO2H(TFA)/K2S2O8 just by tuning the concentrations of arenes and TFA under mild conditions. A proposed mechanism containing two-step aromatic C−H activation on this novel intermolecular cross-coupling of arenes is also suggested and partly supported by experiments.

Nickel(0)/Imidazolium Carbene Catalyst System for Efficient Cross‐Coupling of Aryl Bromides and Chlorides with Organomanganese Reagents.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

A facile synthesis of unsymmetrical biaryls via coupling reaction of aryl halides with sodium tetraphenylborate catalysed by MCM-41-supported thioether palladium(0) complex

Various functionalised unsymmetrical biaryls can be synthesised in high to excellent isolated yields via coupling reaction of aryl iodides or bromides with NaBPh4 catalysed by MCM-41-supported thioether palladium(0) complex. This palladium complex can be easily recovered and reused many times without loss of activity.

Synthesis of o, m-cymene-cored biaryls through a carbanion-induced ring transformation strategy

Aromatic compounds derived from two or more ‘isoprene units’ are the core structures found in several natural products of biological importance. Among them, cymene derivatives are of particular interest due to the unique structural and biological properties associated with them. In this letter, we describe an expeditious synthesis of cymene-cored unsymmetrical biaryls functionalized with donor and acceptor substituents prepared in excellent yields by the carbanion-induced ring transformation of 2 H-pyran-2-ones with ketones.

Palladium‐Catalyzed Homocoupling and Cross‐Coupling Reactions of Aryl Halides in Poly(ethylene glycol).

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Nickel(0)/Imidazolium Carbene Catalyst System for Efficient Cross‐Coupling of Aryl Bromides and Chlorides with Organomanganese Reagents

AbstractN,N′‐Bis(2,6‐diisopropylphenyl)imidazolium chloride associated with nickel(II) acetylacetonate (3–5 mol %) was used as catalyst to efficiently cross‐couple functionalized aryl bromides with organomanganese reagents. The reactions were performed between 0 °C and room temperature, giving unsymmetrical biaryls in 0.25 to 24 h with 52 to 100 % yields for isolated materials. Aryl chlorides showed slightly diminished reactivity in Ni/2 IPr‐catalyzed cross‐couplings and good yields could only be attained with activated or neutral substrates.

Acetyltrimethylsilane: A Novel Reagent for the Transformation of 2H‐Pyran‐2‐ones to Unsymmetrical Biaryls.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Palladium-Catalyzed Homocoupling and Cross-Coupling Reactions of Aryl Halides in Poly(ethylene glycol)

The direct coupling of aryl halides to prepare symmetrical and unsymmetrical biaryls were performed successfully in poly(ethylene glycol) (PEG) using Pd(OAc)2 as the catalyst in the absence of other additives or reductants. The selectivity toward biaryl depended on the amount of PEG used. Excessive PEGs induce the increase of hydrodehalogenation product, and the best selectivity to biaryl is obtained when the concentration of the hydroxyl group in PEG achieves 100 mol % relative to aryl halides. The catalyst system could be recycled and reused up to five times with no loss of catalytic activity.

Oxovanadium(v)-catalyzed oxidative biaryl synthesis from organoborate under O2

Oxidative ligand coupling of organoborates was catalyzed by VO(OEt)Cl(2) under oxygen atmosphere, which provides a versatile method for the selective synthesis of symmetrical or unsymmetrical biaryls.

Acetyltrimethylsilane: A Novel Reagent for the Transformation of 2H-Pyran-2-ones to Unsymmetrical Biaryls

[reaction: see text] An expeditious synthesis of unsymmetrical biaryls functionalized with electron-withdrawing or -donating substituents is described and illustrated by carbanion-induced ring transformation of 2H-pyran-2-one using acetyltrimethylsilane (ATMS) as a novel reagent in good yield. The novelty of the reaction lies in the creation of an aromatic ring from 2H-pyran-2-ones via two-carbon insertion from ATMS used as a source of carbanion.

Nanocrystalline Magnesium Oxide‐Stabilized Palladium(0): An Efficient and Reusable Catalyst for Suzuki and Stille Cross‐Coupling of Aryl Halides

AbstractA nanocrystalline magnesium oxide‐stabilized palladium(0) catalyst is prepared by counterion stabilization of PdCl42− with nanocrystalline MgO followed by reduction. This ligand‐free heterogeneous nanocrystalline MgO‐stabilized nanopalladium [NAPMgPd(0)] catalyst using the basic MgO in place of basic ligands exhibits excellent activity in Suzuki and Stille cross‐coupling of haloarenes (chloro, bromo and iodo) to afford the unsymmetrical biaryls. The catalyst is quantitatively recovered by simple filtration and reused for four cycles with almost consistent activity.

Regioselective Synthesis of Functionally Congested Biaryls Through a Novel C—C Bond Formation Reaction.

AbstractFor Abstract see ChemInform Abstract in Full Text.