Palladium‐Catalyzed Intermolecular Aryliodination of Internal Alkynes

A completely atom economical palladium‐catalyzed addition reaction has been developed to stereoselectively access functionalized tetrasubstituted alkenyl iodides. The palladium catalyst, which bears an electron‐poor bidentate ligand rarely employed in catalysis, is essential to promote the high yielding and chemoselective intermolecular reaction between equimolar amounts of an alkyne and an aryl iodide. This new carbohalogenation reaction is an attractive alternative to traditional synthetic methods, which rely on multistep synthetic sequences and protecting‐group manipulations.     

Desulfinylative Pd-catalyzed coupling reaction of arenediazonium salt with aryl sulfinates to give unsymmetrical biaryls

An efficient route for the synthesis of unsymmetrical biaryls was developed via palladium catalyzed reaction of arenediazonium salts and aryl sulfinates under inert atmosphere. This synthesis involves cascade processes. Tetrabutylammonium iodide was used as an iodide source for in situ formation of aryl iodide, followed by desulfinylative cross-coupling reaction between aryl sulfinates and aryl iodides. A wide range of biaryls were selectively prepared in one pot from simple substrates in good to excellent yields.     

Synthesis of aryl azides and vinyl azides via proline-promoted CuI-catalyzed coupling reactions

The coupling reaction of aryl halides or vinyl iodide with sodium azide under catalysis of CuI/L-proline works at relatively low temperature to provide aryl azides or vinyl azides in good to excellent yields.     

Catechol violet as new, efficient, and versatile ligand for Cu(I)-catalyzed C-S coupling reactions

Combination of CuI and Catechol violet (CuI-CV) was employed as catalyst for the first time in the C-S coupling reaction of a wide variety of aromatic halides, such as aryl iodides, bromo pyridines, activated aryl chlorides, and vinyl iodide with thiols to afford the corresponding thioethers in good to excellent yields. Broad range of functional group tolerance present in both the coupling partners has been observed in this reaction protocol.     

Regio- and stereoselective route to tetrasubstituted olefins by the palladium-catalyzed three-component coupling of aryl iodides, internal alkynes, and arylboronic acids

[reaction: see text] The Pd-catalyzed three-component coupling of readily available aryl iodides, internal alkynes, and arylboronic acids provides a convenient, one-step, regio- and stereoselective route to tetrasubstituted olefins in good to excellent yields, although electron-poor aryl iodides and dialkylalkynes normally afford only low yields under our standard reaction conditions. The proper combination of substrates and reaction conditions is important for high yields. The presence of water generally substantially increases the yields of the desired tetrasubstituted olefins. The reaction involves cis-addition of the aryl group from the aryl iodide to the less hindered or more electron-rich end of the alkyne, while the aryl group from the arylboronic acid adds to the other end. A modified, room-temperature procedure has also been successfully developed, which works very well for some substrates. Tamoxifen and its derivatives are synthesized in a concise, regio- and stereoselective manner by applying our synthetic protocol.     

Synthesis of symmetrical and unsymmetrical N,N'-diaryl guanidines via copper/N-methylglycine-catalyzed arylation of guanidine nitrate

CuI/N-methylglycine-catalyzed coupling reaction of guanidine nitrate with both aryl iodides and bromides takes place at 70-100 °C, affording symmetrical N,N'-diaryl guanidines with good to excellent yields. Unsymmetrical N,N'-diaryl guanidines can be assembled via monoarylation of guanidine nitrate with aryl iodides bearing a strong electron-withdrawing group and subsequent coupling with another aryl iodide.     

Improved studies of cross‐coupling reactions of 5‐(tri‐n‐butystannyl)‐ and 5,5′‐bis(tri‐n‐butylstannyl)‐2,2′‐bithiophene with aryl halides

Stille coupling under standard conditions proceeds in low yield when using hindered organostannanes (1) or (2) and aryl bromide partners. The inclusion of aryl iodide instead of aryl bromide with the same organostannanes, significantly improves the efficiency of the coupling, providing a variety of desired products in good to excellent yield. The yields of Stille coupling are compared to the different reactivity of aryl halides. This study of Stille coupling with different aryl halides are documented and rationalized.     

Sonogashira Coupling Reaction with Palladium Powder and Potassium Fluoride in Methanol

A Sonogashira coupling reaction of aromatic halides with terminal alkynes in the presence of palladium powder,potassium fluoride,cuprous iodide and triphenylphosphine in methanol,giving the corresponding coupling products aryl alkynes in good to excellent yiekls,was investigated.     

An efficient, microwave-assisted, one-pot synthesis of indoles under Sonogashira conditions

A microwave-assisted, one-pot, three-component coupling reaction for the synthesis of indoles has been developed. The reaction is carried out in two steps under standard Sonogashira coupling conditions from an N-substituted/N,N-disubstituted 2-iodoaniline and a terminal alkyne, followed by the addition of acetonitrile and an aryl iodide. A variety of polysubstituted indoles have been prepared in moderate to excellent yields using the present method.     

Mild and efficient copper-catalyzed cyanation of aryl iodides and bromides

An efficient copper-catalyzed cyanation of aryl iodides and bromides is reported. Our system combines catalytic amounts of both copper salts and chelating ligands. The latter, which have potential nitrogen- and/or oxygen-binding sites, have never previously been used in this type of reaction. A protocol has been developed that enables the cyanation of aryl bromides through the copper-catalyzed in situ production of the corresponding aryl iodides using catalytic amounts of potassium iodide. Aryl nitriles are obtained in good yields and excellent selectivities in relatively mild conditions (110 degrees C) compared with the Rosenmund-von Braun cyanation reaction. Furthermore, the reaction is compatible with a wide range of functional groups including nitro and amino substituents. The protocol reported herein involves two main innovations: the use of catalytic amounts of ligands and the use of acetone cyanohydrin as the cyanating agent in copper-mediated cyanation reactions.     

Synthesis and characterization of a polymer-anchored palladium(II) Schiff base complex and its catalytic efficiency in phosphine-free Sonogashira coupling reactions

A polymer-anchored Pd(II) Schiff base complex has been synthesized by reacting a polymeric amine with 2-pyridinecarboxaldehyde to get the polymer-anchored Schiff base, which was then reacted with palladium acetate. The catalyst was characterized by physicochemical and spectroscopic methods. It shows excellent catalytic activity in the Sonogashira coupling of phenylacetylene with aryl halides using triethylamine as a base and copper iodide as a co-catalyst in water under open air at 70 °C. We have also studied the effects of base and solvent on the coupling reaction. Sonogashira reactions of phenylacetylene with a variety of functionalized aryl halides were performed under the optimized reaction conditions. This catalyst gives excellent yields without the use of phosphine ligands. Further experiments showed that the catalyst can be used five times without much loss in the catalytic activity.     

The Sonogashira coupling reaction catalyzed by ultrafine nickel(0) powder

The Sonogashira coupling reaction catalyzed by ultrafine nickel(0) powder has been developed; terminal alkynes couple with aryl, alkenyl iodide and aryl bromide in the presence of cuprous iodide, triphenylphosphine, potassium hydroxide and ultrafine particle nickel(0) to provide the corresponding cross-coupling products with high yields.     

Facile synthesis of ferrocenylamines in aqueous hydrotropic solution using microwaves

Microwave-assisted synthesis of secondary and tertiary ferrocenylamines is achieved by using an amine exchange reaction between ferrocenylmethyltrimethyl ammonium iodide and aryl amines in aqueous hydrotropic solution. The synthesis proceeds in excellent yields within short reaction times.     

Copper-catalyzed Ullmann coupling under ligand- and additive-free conditions. Part 2: S-Arylation of thiols with aryl iodides

S-Arylation of a wide variety of substituted aryl and aliphatic thiols with aryl halides catalyzed by copper iodide under mild ligand- and additive-free conditions (ⁿBu₄NBr, PhMe, NaOH, reflux, 22 h) is accomplished in good to excellent product yields (up to 96%).     

Sonogashira Coupling Reaction with Palladium Powder,Potassium Fluoride in Aqueous Media

Abstract

A Sonogashira coupling reaction of aromatic iodides and bromides with terminal alkynes in the presence of palladium powder, potassium fluoride, cuprous iodide, and triphenylphosphine in aqueous media was developed. The reaction generates the corresponding coupling products aryl alkynes in good to excellent yields.     

无催化剂微波促进下C—O,C—N和C—S交叉偶联反应研究

在无金属催化剂的条件下,利用微波加热促进C—O,C—N和C—S交叉偶联反应.实验发现以DMSO为溶剂,t-BuOK为碱,利用微波加热,活化的氯代芳烃能与各类亲核试剂顺利反应,得到中等及优良的产率.     

Synthesis of isoindol-1-ylphosphonate derivatives via Pd(0)-catalyzed reaction of α-amino (2-alkynylphenyl) methylphosphonate with aryl iodide

α-Amino (2-alkynylphenyl) methylphosphonate, which was generated from 2-alkynyl benzaldehyde, amine, and diethyl phosphate, reacted with aryl iodide at room temperature in the presence of catalytic amount of Pd₂(dba)₃ and DABCO in acetone, leading to the desired isoindol-1-ylphosphonate derivatives in good to excellent yields.     

A novel Heck reaction catalyzed by Co hollow nanospheres in ligand-free condition

Heck reaction catalyzed by cobalt hollow nanospheres has been developed; the coupling of alkenes with aryl iodide or aryl bromide in the presence of potassium carbonate provides the corresponding products with moderate to good yields, which reveals obvious advantages such as low-cost catalyst, ligand-free condition, the recyclability of the catalyst and simple experimental operation.     

Chiral benzimidazole derived bis-phenyl triazoles as chiroptical sensors for iodide and chiral amines

A series of chiral 2-hydroxy ethyl/benzyl benzimidazole based aryl triazole tweezers have been prepared using click chemistry in high yields. Chiral pool strategy has been used to obtain the benzimidazole-based tweezers in very high enantiomerically enriched form. The aryl triazole tweezers, S -(−)- 5a and S -(+)- 8a displayed a high degree of selectivity for iodide anion over other anions, including other halides. The aryl triazole tweezers, S -(−)- 5a and S -( + )- 8a display significant enantio-discrimination for chiral amines. The chiral recognition studies were carried out using UV and circular dichroism (CD) spectroscopy. NMR analysis has been used for establishing the sites for ligation of the iodide anion.     

Application of directed orthometalation toward the synthesis of aryl siloxanes

A selection of ortho-substituted aryl siloxanes have been prepared by directed orthometalation protocols. These siloxanes can be prepared in high yields and purity by use of a diverse selection of ortho-directing groups and electrophilic siloxane derivatives. The siloxanes are employed in palladium-catalyzed cross-coupling reactions with aryl bromides to generate unsymmetrical ortho-substituted biaryls in good to excellent yields.