Magnesium-induced copper-catalyzed synthesis of unsymmetrical diaryl chalcogenide compounds from aryl iodide via cleavage of the Se-Se or S-S bond

The methodology for a copper-catalyzed preparation of diaryl chalcogenide compounds from aryl iodides and diphenyl dichalcogenide molecules is reported. Unsymmetrical diaryl sulfide or diaryl selenide can be synthesized from aryl iodide and PhYYPh (Y = S, Se) with a copper catalyst (CuI or Cu(2)O) and magnesium metal in one pot. This reaction can be carried out under neutral conditions according to an addition of magnesium metal as the reductive reagent. Furthermore, it is efficiently available for two monophenylchalcogenide groups generated from diphenyl dichalcogenide.     

Alkyl- or arylthiolation of aryl iodide via cleavage of the S-S bond of disulfide compound by nickel catalyst and zinc

Various aryl sulfides can be synthesized by nickel-catalyzed alkyl- or arylthiolation of aryl iodide with a disulfide compound. This reaction produces Ni(0) from NiBr2-bpy by the reduction with zinc, and this generated complex works as an activating species to convert ArI into ArSR under neutral conditions. Furthermore, this system enables the use of two RS groups in (RS)2.     

Solvent control of product diversity in palladium-catalyzed addition of arylboronic acid to aryl aldehydes

In Pd-catalyzed arylboronic acid addition to aryl aldehydes, the expected carbinol or asymmetrical ether can be obtained as the major product by altering aqueous solvent composition. Exploiting this methodology with 2-formylbiphenyls as reaction partner, a fluorene scaffold can be readily constructed in two steps.     

A STUDY ON THE SELECTIVE REDUCTION OF AROMATIC AMIDE WITH LiAlH_4

In the synthesis of l-phenyl-5-substituted amino-4-pyrazole N-alkyl amide,it was found for the first time that one of the two aromatic amido groups in the moleculeof 1-phenyl-5-benzoyl amino-4-pyrazole N-alkyl amide was reduced selectively by LiAlH_4.new conclusion was drawn after several experiments have been done that ortho-amino(orsubstituted amino)aryl amide or the aryl amide with its ortho substituent which canbe reduced into an amino group(or substituted amino group)can not be reduced by LiAlH_4.It was further rationalized by quantum chemical calculation.     

A simple catalyst for aqueous phase Suzuki reactions based on palladium nanoparticles immobilized on an ionic polymer

Palladium nanoparticles immobilized on a cross-linked imidazolium-containing polymer were evaluated as a catalyst for Suzuki carbon-carbon cross-coupling reactions using water as the solvent. The nanocatalysts show good catalytic activities for aryl iodides and aryl bromides and moderate activity with aryl chloride substrates. Coupling of sterically hindered substrates could also be achieved in reasonable yields. The heterogeneous catalyst is stable, can be stored without precautions to exclude air or moisture, and can be easily recycled and reused.     

Achieving Vinylic Selectivity in Mizoroki–Heck Reaction of Cyclic Olefins

In Heck reactions of cyclic olefins, the products usually have aryl groups that end up at the allylic and/or homoallylic position. We herein report new selectivity that adds aryl groups to the vinylic position. Cyclic olefins of various ring size worked well. The desired isomers were produced by palladium–hydride‐catalyzed isomerization of the initial products. Thus, a specific catalyst must be used so that it can perform two jobs under one set of reaction conditions.     

Mono- and beta,beta-double-Heck reactions of alpha,beta-unsaturated carbonyl compounds in aqueous media

Optimized reaction conditions for the mono- and beta,beta-diarylation of electron-deficient alkenes in aqueous media catalyzed either by a p-hydroxyacetophenone oxime-derived palladacycle or by palladium(II) acetate under phosphine-free conditions and in the presence of (dicyclohexyl)methylamine as base are described. Regioselective monoarylation of unsubstituted and substituted alpha,beta-unsaturated carbonyl compounds takes place with aryl iodides at 120 degrees C in water. Aqueous N,N-dimethylacetamide (DMA), tetra-n-butylammonium bromide (TBAB) as additive, and the palladacycle as catalyst are the most efficient conditions for the coupling with aryl bromides, good stereoselectivities being also obtained in the arylation of crotonates and itaconates, whereas cinnamic derivatives afford lower steroselectivity, with the exception of cinnamic acid and nitrile. beta,beta-Diarylation of unsubstituted alpha,beta-unsaturated carbonyl compounds can be controlled by using higher loading of the palladacycle and can be performed in refluxing water for aryl iodides, whereas DMA must be used for aryl bromides. Microwave irradiation can be used in the monoarylation of tert-butyl acrylate with aryl iodides in water or the coupling between ethyl cinnamate and aryl bromides in aqueous DMA.     

Copper-catalyzed N-arylation of 2-arylindoles with aryl halides

10 mol% Cul combined with the DMEDA ligand can efficiently catalyze the N-arylation of 2-arylindoles with aryl iodides and aryl bromides in good to excellent yields. The aryl halides bearing electron-rich or electron-deficient functional groups can be well tolerated under this mild reaction conditions.     

Palladium‐Catalyzed Direct C?H Functionalization of Benzoquinone

A direct Pd‐catalyzed C H functionalization of benzoquinone (BQ) can be controlled to give either mono‐ or disubstituted BQ, including the installation of two different groups in a one‐pot procedure. BQ can now be directly functionalized with aryl, heteroaryl, cycloalkyl, and cycloalkene groups and, moreover, the reaction is conducted in environmentally benign water or acetone as solvents.     

Rapid, easy cyanation of aryl bromides and chlorides using nickel salts in conjunction with microwave promotion

We report here a fast, easy, and efficient method for the preparation of aryl nitriles from aryl bromides and chlorides. The methodology for aryl bromides involves the use of either Ni(CN)(2) or NaCN and NiBr(2). With aryl chlorides, a mix of NaCN and NiBr(2) is used and the reaction proceeds via the in situ formation of the corresponding aryl bromide. The reaction can be performed in air and is complete within 10 min.     

Palladium‐Catalyzed Direct CH Functionalization of Benzoquinone

A direct Pd‐catalyzed C? H functionalization of benzoquinone (BQ) can be controlled to give either mono‐ or disubstituted BQ, including the installation of two different groups in a one‐pot procedure. BQ can now be directly functionalized with aryl, heteroaryl, cycloalkyl, and cycloalkene groups and, moreover, the reaction is conducted in environmentally benign water or acetone as solvents.     

One-pot synthesis of unsymmetrical triarylamines from aniline precursors

The "one-pot" synthesis of triarylamines from an aniline and two different aryl halides is described. A catalytic system composed of Pd2(dba)3/P(t-Bu)2-o-biphenyl (1) is used to prepare a variety of triarylamines in a single flask by the coupling of an aniline with an aryl bromide and aryl chloride. The synthesis of triarylamines containing a heterocyclic aryl group is also described by employing a one-flask, two-step method. These methods can be used to synthesize both discrete triarylamines and a triarylamine library.     

Palladium catalysed 3-component cascade synthesis of bis(2-arylallyl) tertiary amines from aryl iodides,allene and primary amines

A 3-component cascade synthesis of bis(2-arylallyl) tertiary amines from aryl iodide, allene and primary aliphatic amines is described; chiral amines give analogous products with no detectable racemisation; mixtures of two different aryl iodides can be utilised to give the mixed tertiary amines as the sole, or major, product; the reaction is sensitive to stereoelectronic effects which lead to mono(2-arylallyl) secondary amines.     

Facile photochemical transformation of alkyl aryl selenides to the corresponding carbonyl compounds by molecular oxygen: use of selenides as masked carbonyl groups

Alkyl aryl selenides with and without functional groups on the alkyl group were transformed efficiently into the corresponding carbonyl compounds, particularly primary alkyl aryl selenides in good yields, by a simple photolysis in the presence of air or oxygen. This transformation can be conducted without protection of functional groups. The yield of carbonyl compounds was much affected by the solvent viscosity, reaction temperature, concentration of dissolved oxygen in the solvents, wavelength of light, and structure of the aryl substituents. The present study indicates that aryl selenides can be considered as a masked carbonyl group that can be easily converted to a carbonyl group by very mild reaction conditions even in the presence of various unprotected functional groups. Therefore, this functional group transformation can be used as an important tool in organic synthesis due to its simplicity and mild reaction condition.     

Selective Heck reaction of aryl bromides with cyclopent-2-en-1-one or cyclohex-2-en-1-one

The selective Heck reaction of cyclopent-2-en-1-one or cyclohex-2-en-1-one with aryl bromides gives a simple access to the corresponding 3-arylcycloalk-2-en-1-ones. The choice of the base was found to be crucial to avoid the formation of 3-arylcyclopentanones or 3-arylcyclohexanones as side-products. Using KF as base, DMF as solvent and Pd(OAc)₂ as catalyst, the target products were obtained in moderate to good yields with a variety of aryl bromides. Substituents such as fluoro, trifluoromethyl, acetyl, benzoyl, formyl, ester or nitrile on the aryl bromide are tolerated. Sterically congested aryl bromides or bromopyridines can also be employed.     

Intramolecular Metal‐Free Oxidative Aryl–Aryl Coupling: An Unusual Hypervalent‐Iodine‐Mediated Rearrangement of 2‐Substituted N‐Phenylbenzamides

Hypervalent‐iodine‐mediated oxidative coupling of the two aryl groups in either 2‐acylamino‐N‐phenyl‐benzamides or 2‐hydroxy‐N‐phenylbenzamides, with concomitant insertion of the ortho‐substituted N or O atom into the tether, has been described for the first time. This unusual metal‐free rearrangement reaction involves an oxidative C(sp²)? C(sp²) aryl–aryl bond formation, cleavage of a C(sp²)? C(O) bond, and a lactamization/lactonization. Furthermore, unsymmetrical diaryl compounds can be easily obtained by removing the tether within the cyclized product.     

Ligand-free highly effective iron/copper co-catalyzed formation of dimeric aryl ethers or sulfides

Highly selective coupling of diiodoarenes with phenols or phenthiols can be performed by using a low-cost, benign character and readily available Fe/Cu catalytic system in the absence of ligands. It is noteworthy that the desired dimeric aryl ethers or sulfides could be obtained in high yields by coupling between diiodoarenes and phenols, or diphenols with aryl iodides.     

A catalytic amount of nickel(II) chloride hexahydrate and 1,2-ethanedithiol is a good combination for the cleavage of tetrahydropyranyl (THP) and tert-butyldimethylsilyl (TBS) ethers

Various THP and TBS ethers can be unmasked easily to the corresponding hydroxyl compounds in good yields by using a combination of a catalytic amount of nickel(II) chloride hexahydrate and 1,2-ethanedithiol at room temperature. In addition, alkyl TBS ethers can be hydrolyzed chemoselectively in the presence of aryl TBS ethers. Moreover, alkyl TBS ethers can be cleaved easily in the presence of alkyl or aryl THP ethers using the same conditions.     

Amino acid promoted CuI-catalyzed C-N bond formation between aryl halides and amines or N-containing heterocycles

CuI-catalyzed coupling reaction of electron-deficient aryl iodides with aliphatic primary amines occurs at 40 degrees C under the promotion of N-methylglycine. Using l-proline as the promoter, coupling reaction of aryl iodides or aryl bromides with aliphatic primary amines, aliphatic cyclic secondary amines, or electron-rich primary arylamines proceeds at 60-90 degrees C; an intramolecular coupling reaction between aryl chloride and primary amine moieties gives indoline at 70 degrees C; coupling reaction of aryl iodides with indole, pyrrole, carbazole, imidazole, or pyrazole can be carried out at 75-90 degrees C; and coupling reaction of electron-deficient aryl bromides with imidazole or pyrazole occurs at 60-90 degrees C to provide the corresponding N-aryl products in good to excellent yields. In addition, N,N-dimethylglycine promotes the coupling reaction of electron-rich aryl bromides with imidazole or pyrazole to afford the corresponding N-aryl imidazoles or pyrazoles at 110 degrees C. The possible action of amino acids in these coupling reactions is discussed.     

The copper-catalyzed N-arylation of indoles

A general method for the N-arylation of indoles using catalysts derived from CuI and trans-1,2-cyclohexanediamine (1a), trans-N,N'-dimethyl-1,2-cyclohexanediamine (2a), or N,N'-dimethyl-ethylenediamine (3) is reported. N-Arylindoles can be produced in high yield from the coupling of an aryl iodide or aryl bromide with a variety of indoles.