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.     

Sonogashira reaction of aryl halides with propiolaldehyde diethyl acetal catalyzed by a tetraphosphine/palladium complex

All-cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane/[PdCl(C₃H₅)]₂ efficiently catalyzes the Sonogashira reaction of propiolaldehyde diethyl acetal with a variety of aryl bromides and chlorides. A minor electronic effect of the substituents of the aryl bromide was observed. Similar reaction rates were observed in the presence of activated aryl bromides such as 4-trifluoromethylbromobenzene and deactivated aryl bromides such as bromoanisole. Turnover numbers up to 95,000 can be obtained for this reaction. Even aryl chlorides and heteroarylbromides or chlorides have been successfully alkynylated with this catalyst. Moreover, a wide variety of substituents on the aryl halide such as fluoro, trifluoromethyl, acetyl, benzoyl, formyl, nitro, dimethylamino or nitrile are tolerated.     

Palladium-catalyzed Heck reaction of aryl chlorides under mild conditions promoted by organic ionic bases

An efficient Pd-catalyzed Heck reaction of aryl chlorides with olefins under mild conditions is described. High yields of products were achieved with n-Bu(4)N(+)OAc(-) as base. Significantly, the temperature of the Heck reaction of diverse nonactivated aryl chlorides can be lowered to 80 °C. The new reaction system can also tolerate a wider range of olefins.     

Well-defined NHC–Pd(II)–Im (NHC=N-heterocyclic carbene; Im=1-methylimidazole) complex catalyzed C–N coupling of primary amines with aryl chlorides

We report herein a well-defined NHC–Pd(II)–Im (NHC=N-heterocyclic carbene; Im=1-methylimidazole) complex catalyzed C–N coupling of primary amines with aryl chlorides. Under the optimal reaction conditions, a variety of primary amines can be coupled with aryl chlorides to give the amination products in good to high yields within 4 h. It is worthy of noting here that the NHC–Pd(II)–Im complex showed especially high catalytic activity toward challenging sterically hindered substrates including both of aryl amines and aryl chlorides. In addition, alkyl amines were also proved to be suitable reaction partners to give the corresponding amination products in good to high yields.     

Palladium‐catalysed reductive carbonylation of aryl halides with iron pentacarbonyl for synthesis of aromatic aldehydes and deuterated aldehydes

The first use of iron pentacarbonyl is described for the novel and efficient conversion of aryl iodides, bromides and chlorides into their corresponding aryl aldehydes and/or aryl deuterated aldehydes. The reaction is catalysed with Pd(0) in aqueous N,N‐dimethylformamide at atmospheric pressure. In this protocol, neither gaseous hydrogen nor any reducing agent is required for the formation of the carbonylated product. The reaction can be performed without a P(III) ligand for aryl iodides; however, employing a P(III) ligand is necessary to perform the reaction with aryl bromides and chlorides. Copyright © 2015 John Wiley & Sons, Ltd.     

Pd2(dba)3/P(i-BuNCH2CH2)3N-catalyzed Stille cross-coupling of aryl chlorides

[reaction: see text] The Pd(2)(dba)(3)/P(i-BuNCH(2)CH(2))(3)N (1d) catalyst system is highly effective for the Stille cross-coupling of aryl chlorides with organotin compounds. This method represents only the second general method for the coupling of aryl chlorides. Other proazaphosphatranes possessing benzyl substituents also generate very active catalysts for Stille reactions. Noteworthy features of the method are: (a) commercial availability of ligand 1d, (b) the wide array of aryl chlorides that can be coupled, and (c) applicability to aryl, vinyl, and allyl tin reagents.     

环钯-[PPh4]Br体系催化氯代芳烃的Heck芳基化反应研究

以氯代芳烃为底物，季鏻盐[PPh4]Br为助催化剂，用于环钯催化的Heek芳基化反应．结果表明，在环钯-[PPh4]Br催化体系中，以Na2CO3作为碱性试剂，使用0．3mol％Pd的环钯催化剂催化氯苯的Heek反应，就可得到比较高的产率（88％）和转化率（90％）．对于大部分卤代芳烃Heck反应而言，环钯-[PPh4]Br是一种有效的催化体系，即使是对含推电子基团的不活泼的氯代芳烃，在此体系中也能获得比较好的结果．此外，文中还探讨了反应温度、[PPh4]Br／Pd比值及催化剂回用对反应活性的影响．     

Kumada coupling of aryl, heteroaryl, and vinyl chlorides catalyzed by amido pincer nickel complexes

A series of amido pincer complexes of nickel were examined for their catalysis in the Kumada cross-coupling reaction. The P,N,O-pincer nickel complexes tested are active catalysts for the cross-coupling of aryl, heteroaryl, and vinyl chlorides with aryl Grignard reagents. The reactions can proceed at room temperature and tolerate functional groups in aryl chlorides with the aid of LiCl and ZnCl(2) additives.     

P[N(i-Bu)CH2CH2]3N: a versatile ligand for the Pd-catalyzed amination of aryl chlorides

[reaction: see text] Palladium-catalyzed amination reactions of aryl chlorides with amines proceeded in the presence of the bicyclic triaminophosphine P[N(i-Bu)CH(2)CH(2)](3)N to afford the corresponding arylamines in good to excellent yields. Electron-poor, electron-neutral, and electron-rich aryl chlorides all participated with equal ease.     

A General Palladium‐Catalyzed Hiyama Cross‐Coupling Reaction of Aryl and Heteroaryl Chlorides

A general palladium‐catalyzed Hiyama cross‐coupling reaction of aryl and heteroaryl chlorides with aryl and heteroaryl trialkoxysilanes by a Pd(OAc)₂/ L2 catalytic system is presented. A newly developed water addition protocol can dramatically improve the product yields. The conjugation of the Pd/ L2 system and the water addition protocol can efficiently catalyze a broad range of electron‐rich, ‐neutral, ‐deficient, and sterically hindered aryl chlorides and heteroaryl chlorides with excellent yields within three hours and the catalyst loading can be down to 0.05 mol % Pd for the first time. Hiyama coupling of heteroaryl chlorides with heteroaryl silanes is also reported for the first time. The reaction can be easily scaled up 200 times (100 mmol) without any degasification and purification of reactants; this facilitates the practical application in routine synthesis.     

Diaminophosphine oxides as preligands for Ni-catalyzed Suzuki cross-coupling reactions of aryl chlorides with arylboronic acids

The first investigation of air- and moisture-stable diaminophosphine oxides as preligands in the Ni-catalyzed Suzuki cross-coupling reactions of aryl chlorides with arylboronic acids has been reported. The results show that under the optimized reaction conditions, the new catalytic system with a Ni(II) σ-aryl complex as precatalyst and a diaminophosphine oxide as preligand tolerates a variety of functional groups and is efficient for both electron-rich and electron-deficient aryl chlorides, though it shows higher efficiency for activated arylboronic acids than deactivated ones. Steric effects were observed for both aryl chlorides and arylboronic acids.     

Suzuki-Miyaura, alpha-ketone arylation and dehalogenation reactions catalyzed by a versatile N-heterocyclic carbene-palladacycle complex

[reaction: see text] The activity of the complex (IPr)PdCl(eta2-N,C-C12H7NMe2), 1 [IPr = (N,N'-bis(2,6-diisopropylphenyl)imidazol)-2-ylidene], in the Suzuki-Miyaura cross-coupling reaction involving unactivated aryl chlorides and triflates with arylboronic acids at room temperature in technical grade 2-propanol is described. These conditions allow for the synthesis of di- and tri-ortho-substituted biaryls in very short reaction times. This complex also displays very high activity for alpha-ketone arylation and dehalogenation reactions of activated and unactivated aryl chlorides.     

Palladium-catalyzed Stille cross-couplings of sulfonyl chlorides and organostannanes

Arene and phenylmethanesulfonyl chlorides can be cross-coupled with aryl, heteroaryl, and alkenylstannanes with desulfitation in the presence of 10 mol % CuBr.Me2S, 1.5 mol % Pd2dba3, and 5 mol % tri-2-furylphosphine in tetrahydrofuran or toluene under reflux. This extension of the Stille cross-coupling reaction realizes a new and economical method for the generation of C-C bonds. The palladium-catalyzed carbonylative Stille cross-coupling reactions of arenesulfonyl chlorides and organostannanes in the presence of CO (60 bar) at 110 degrees C in toluene generate the corresponding ketones. Arenesulfonyl chlorides are more reactive than aryl chlorides and aryl bromides in their Stille cross-coupling with organostannanes but less reactive than aryl iodides. The new methods disclosed for the generation of C-C bonds open new possibilities for medicinal chemistry and material sciences.     

Mild and general methods for the palladium-catalyzed cyanation of aryl and heteroaryl chlorides

[reaction: see text] New methods for the palladium-catalyzed cyanation of aryl and heteroaryl chlorides have been developed, featuring sterically demanding, electron-rich phosphines. Highly challenging electron-rich aryl chlorides, in addition to electron-neutral and electron-deficient substrates, as well as nitrogen- and sulfur-containing heteroaryl chlorides can all undergo efficient cyanation under relatively mild conditions using readily available materials. In terms of substrate scope and temperature, these methods compare very favorably with the state-of-the-art cyanations of aryl chlorides.     

Suzuki Coupling of Cyclopropylboronic Acid With Aryl Halides Catalyzed by a Palladium–Tetraphosphine Complex

The tetraphosphine all‐cis‐1,2,3,4‐tetrakis(diphenylphosphinomethyl)cyclopentane (Tedicyp) in combination with [Pd(C₃H₅)Cl]₂ affords a very efficient catalyst for the coupling of cyclopropylboronic acid with aryl bromides and aryl chlorides. Higher reactions rates were observed with aryl bromides than with aryl chlorides; however, even in the presence of 1–0.4% of catalyst, a few aryl chlorides gave the coupling products in good yields. A wide variety of substituents such as alkyl, methoxy, trifluoromethyl, acetyl, benzoyl, formyl, carboxylate, nitro, and nitrile on the aryl halides are tolerated. The coupling reaction of sterically very congested aryl bromides such as bromomesitylene or 2,4,6‐triisopropylbromobenzene also proceeds in good yields.     

Expanding the scope of the Cu assisted Suzuki-Miyaura reaction

Recent advances in the development of the copper facilitated Suzuki-Miyaura reaction are described. Improvements include expansion of substrate scope to include aryl chlorides and polyhalo aryl boronates. It was found that use of S-Phos and X-Phos could accomplish the coupling of 2-pyridyl boronates to aryl chlorides and bromides in shorter reaction times and in higher yield than previously described with DPPF.     

Room-temperature Kumada cross-coupling of unactivated aryl chlorides catalyzed by N-heterocylic carbene-based nickel(II) complexes

The Kumada cross-coupling reaction of a variety of unactivated aryl chlorides, vinyl chlorides, and heteroaryl chlorides catalyzed by nickel(II) complexes containing pyridine-functionalized NHC ligands is described. The catalysts are so active that the reactions proceed at room temperature in excellent yields.     

High turnover number and rapid, room-temperature amination of chloroarenes using saturated carbene ligands

[equation--see text] A catalytic system for the mild amination of aryl chlorides is described. This system consists of a Pd(0) precursor and a dihydroimidazoline carbene ligand, which is generated in situ from its protonated tetrafluoroborate salt (2). Using this catalyst, aryl and heteroaryl chlorides react with secondary amines and anilines within hours at room temperature. Turnover numbers as high as 5000 are obtained at elevated temperatures for reaction of morpholine with an unactivated aryl chloride.     

Cross-coupling of cyclopropyl- and cyclobutyltrifluoroborates with aryl and heteroaryl chlorides

Suitable conditions were found for the Suzuki-Miyaura cross-coupling reaction of potassium cyclopropyl- and cyclobutyltrifluoroborates with aryl chlorides. Both of these secondary alkyl trifluoroborates coupled in moderate to excellent yield with electron-rich, electron-poor, and hindered aryl chlorides to give a variety of substituted aryl cyclopropanes and cyclobutanes.     

Trichloroisocyanuric Acid (TCCA) and N-Chlorosuccinimide (NCS) as Efficient Reagents for the Direct Oxidative Conversion of Thiols and Disulfides to Sulfonyl Chlorides

Abstract

Trichloroisocyanuric acid (TCCA) and N-chlorosuccinimide (NCS) were found to be mild and efficient reagents for the direct oxidative conversion of sulfur compounds to the corresponding arenesulfonyl chlorides in good-to-excellent yields through the oxidative chlorination. The overall process is simple and practical, and it provides convenient access to a variety of aryl or heteroarylsulfonyl chlorides. The mild reaction conditions and the broad substrate scope render this method attractive and complementary to existing syntheses of aryl or heteroarylsulfonyl chlorides.