[Pd(PPh3)2(saccharinate)2]—general catalyst for Suzuki–Miyaura,Negishi cross-coupling and C–H bond functionalization of coumaryl and pyrone substrates

The potential of complex [Pd(PPh₃)₂(saccharinate)₂] 1 in catalyzing Suzuki–Miyaura cross-coupling of 4-halo and 4-bromomethyl coumaryl and pyrone substrates with different aryl boronic acids has been explored. Excellent yields of the desired products are obtained in competitive reaction time and under relatively mild conditions. Negishi cross-coupling of 4-coumaryl tosylate with aryl and alkylzinc reagents has also been performed with good yields of the cross-coupled products obtained in most cases. Intra-molecular C–H bond functionalization of coumaryl ethers also furnished very high yields of synthetically attractive tetracyclic ring systems exhibiting the potential of 1 as a powerful catalyst in synthetically important reactions.     

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.     

Suzuki aryl cross-coupling chemistry using derivatives of 1,1,2,2,9,9,10,10-octafluoro[2.2]paracyclophane

An exploration into the scope of Suzuki aryl cross-coupling chemistry using derivatives of 1,1,2,2,9,9,10,10-octafluoro[2.2]paracyclophane is reported. The coupling of 4-iodo-1,1,2,2,9,9,10,10-octafluoro[2.2]paracyclophane with various aryl boronic acids and boronic acid pinacol esters was successful, with the exception of very sterically demanding systems, such as mesityl. The synthesis of the previously unreported 1,1,2,2,9,9,10,10-octafluoro[2.2]paracyclophanyl-4-boronic acid is described, together with various Suzuki aryl cross-coupling reactions of this new system. Using standard Suzuki methodology, it was possible to prepare dicyclophanes bearing two octafluoro[2.2]paracyclophane units separated by both one and two benzene rings.     

Cross-coupling and dehalogenation reactions catalyzed by (N-heterocyclic carbene)Pd(allyl)Cl complexes

A series of well-defined, air- and moisture-stable (NHC)Pd(allyl)Cl (NHC = N-heterocyclic carbene) complexes has been used in several catalytic reactions: Suzuki-Miyaura cross-coupling, catalytic dehalogenation of aryl halides, and aryl amination. The scope of the three processes using various substrates was examined. A general system involving the use of (IPr)Pd(allyl)Cl as catalyst and NaO(t)Bu as base has proven to be highly active for the Suzuki-Miyaura cross-coupling of activated and unactivated aryl chlorides and bromides, for the catalytic dehalogenation of aryl chlorides, and for the catalytic aryl amination of aryl triflates. All reactions proceed in short reaction times and at mild temperatures. The system has also proven to be compatible with the microwave-assisted Suzuki-Miyaura cross-coupling and catalytic dehalogenation processes, affording yields similar to those of the conventionally heated analogous reactions.     

Room-temperature Ni0-catalyzed cross-coupling reactions of aryl arenesulfonates with arylboronic acids

Room-temperature Ni(0)-catalyzed cross-coupling reactions of aryl arenesulfonates with arylboronic acids are described. The Ni(0) catalyst, derived from Ni(COD)2 and PCy3, proved to be a general one for the Suzuki-Miyaura cross-coupling of a variety of aryl arenesulfonates. The mild reaction condition, the readily availability of the catalyst, and excellent coupling yields make aryl arenesulfonates potentially useful substrates in organic synthesis.     

Oxidative addition of aryl tosylates to palladium(0) and coupling of unactivated aryl tosylates at room temperature

Aryl tosylates are attractive substrates for Pd-catalyzed cross-coupling reactions, but they are much less reactive than the more commonly used aryl triflates. We report the oxidative addition of aryl tosylates to Pd(PPF-t-Bu)[P(o-tolyl)3] and to Pd(CyPF-t-Bu)[P(o-tolyl)3] at room temperature to produce the corresponding palladium(II) aryl tosylate complexes. In the presence of added bromide ions, arylpalladium(II) bromide complexes were formed. The rate of oxidative addition was accelerated by addition of either coordinating or weakly coordinating anions, and the reactions were faster in more polar solvents. The mild conditions for oxidative addition allowed for the development of Pd-catalyzed Kumada couplings and amination reactions of unactivated aryl tosylates at room temperature. The catalysts for these mild couplings of aryl tosylates were generated from palladium precursors and the sterically hindered Josiphos-type ligands that induced oxidative addition of aryl tosylates to Pd(0) at room temperature.     

Cross-coupling reactions of phenylmagnesium halides with fluoroazines and fluorodiazines

The first nickel-catalyzed cross-coupling reactions between fluoroarenes and aryl organometallics using commercially available ligands are described. The nickel-catalyzed cross-coupling reactions between aryl Grignard reagents and fluoroazines and -diazines occurred in THF at room temperature using commercially available 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, or 1,1'-bis(diphenylphosphino)ferrocene as ligand. Various fluoro substrates such as pyridines, diazines (pyrazine, pyridazine), benzodiazines (quinoxaline), and quinolines were successfully involved in the reaction with phenylmagnesium halides (phenylmagnesium chloride, 2-methoxyphenylmagnesium bromide, and 4-methoxyphenylmagnesium bromide). The conditions used also allowed the cross-coupling of 4-fluorotoluene with arylmagnesium reagents.     

经由Domino脱HCl/Pd（OAc）2催化的Heck反应合成查尔酮

通过Domino脱HCl/Pd(OAc)2催化的Heck反应实现了β-氯代烷基芳基酮、酯和酰胺与卤代芳烃的交叉偶联反应,高效合成了查尔酮类化合物。利用原位生成烯酮为中间体进行反应的策略,减少副反应的发生,从而提高反应的效率。该方法对各种官能团的容忍性好,为从氯代烷烃出发直接合成查尔酮类化合物提供了一条新途径。     

Copper-mediated cross-coupling reactions of N-unsubstituted sulfoximines and aryl halides

[reaction: see text] Copper-mediated cross-coupling reactions of sulfoximines with aryl iodides and aryl bromides provide N-arylated sulfoximines in high yields. The method is complementary to the known palladium-catalyzed N-arylation and allows the preparation of N-arylated sulfoximines, which have previously been inaccessible.     

An efficient system for the Pd-catalyzed cross-coupling of amides and aryl chlorides

A catalyst based on a new biarylphosphine ligand (3) for the Pd-catalyzed cross-coupling reactions of amides and aryl chlorides is described. This system shows the highest turnover frequencies reported to date for these reactions, especially for aryl chloride substrates bearing an ortho substituent. An array of amides and aryl chlorides were successfully reacted in good to excellent yields.     

Novel substrates for palladium-catalyzed coupling reactions of arenes

Arenes and heteroarenes are ubiquitous substructures in biologically active agents and new materials. Thus, functionalization ("refinement") of simple arene precursors is still of major importance for preparative organic chemistry. During the last 20 years, especially transition-metal-catalyzed cross-coupling reactions of aryl halides and triflates have given arene chemistry new impetus. The first industrial applications were realized a few years ago. Quite recently, carbonic acid derivatives such as anhydrides and esters have added to the scope of substrates for these coupling reactions. Some recent developments in this area are presented in this Minireview.     

35 years of palladium-catalyzed cross-coupling with Grignard reagents: how far have we come?

This tutorial review is intended to provide the reader with a timely review of major developments and the current state-of-the-art of palladium-catalyzed cross-coupling reactions with Grignard reagents. Organomagnesium reagents, the most reactive and most easily accessible nucleophiles for carbon-carbon bond forming cross-coupling reactions, were the first nucleophiles ever employed in cross-coupling reactions, but have only recently been re-discovered for highly efficient and (stereo)selective coupling reactions. This is mostly a consequence of improved catalyst systems with bulky phosphine, phosphonate or carbene ligands and new metal-halogen exchange procedures for the generation of functionalized Grignard reagents.     

Rapid formation of triarylphosphines by microwave-assisted transition metal-catalyzed C-p cross-coupling reactions

Rapid, direct transition metal-catalyzed C-P(III) cross-coupling reactions were performed by microwave dielectric heating, employing diphenylphosphine and aryl halides/triflates as substrates. Depending on the specific aryl halide/triflate precursor, the highest yields were obtained utilizing heterogeneous or homogeneous Pd or Ni catalysts in DMF or NMP in the presence of KOAc or DABCO as a base. [reaction: see text]     

Microwave-Assisted Cross-Coupling Reaction of Sodium Tetraphenylboratewith Carboxylic Anhydrides Catalyzed by Palladium

Cross-coupling processes of aryl or alkenyl halides with organometallic compounds of main group elements cat alyzed by palladium complexes have been found extensive use in organic synthesis. These cross-coupling reactions offer a powerful tool for the formation of carbon-carbon bonds. [1] The Suzuki-Miyaura cross-coupling reaction has been employed for the synthesis of ketone as well.     

Microwave-promoted cross-coupling of acid chlorides with arylboronic acids: a convenient method for preparing aromatic ketones

Simple catalytic systems for cross-coupling reactions of acyl chlorides with arylboronic acids under microwave conditions were tested. Microwave irradiation facilitated the reaction course. Mild reaction conditions afford the symmetrical and unsymmetrical aryl ketones in reasonable to high yields within a short time. A wide range of substrates bearing an electron-donating or an electron-withdrawing substituent on aryl ring of acid chloride as well as on boronic acid were examined and high yields of ketones were produced.     

A Unified and Practical Method for Carbon–Heteroatom Cross-Coupling using Nickel/Photo Dual Catalysis

While carbon–heteroatom cross-coupling reactions have been extensively studied, many methods are specific and limited to a particular set of substrates or functional groups. Reported here is a general method that allows for C−O, C−N and C−S cross-coupling reactions under one general set of conditions. We propose that an energy transfer pathway, in which an iridium photosensitizer produces an excited nickel(II) complex, is responsible for the key reductive elimination step that couples aryl bromides, iodides, and chlorides to 1° and 2° alcohols, amines, thiols, carbamates, and sulfonamides, and is amenable to scale up via a flow apparatus.     

The palladium-catalyzed cross-coupling reactions of trifluoroethyl iodide with aryl and heteroaryl boronic acid esters

The cross-coupling reactions of 1,1,1-trifluoro-2-iodoethane with aryl and heteroaryl boronic acid esters have been successfully achieved. The new protocol allows for a convenient introduction of trifluoroethyl groups into a variety of aryl and heteroaryl moieties under mild conditions.     

Scyllo-inositol as a convenient protecting group for aryl boronic acids in Suzuki–Miyaura cross-coupling reactions

Herein, we report air- and water-stable borate complexes between scyllo-inositol and aryl boronic acids. The complexes were less reactive than free aryl boronic acids under Suzuki–Miyaura cross-coupling reaction conditions; thus, the borate complexes were used as protected boronic acids. Although protecting groups for organoboronic acids are useful in coupling reactions, especially those used to produce π-conjugated molecules, only a few reports describing the use of protecting groups for boronic acids have been published. The proposed unique structural borate complex provides a novel protective method for aryl boronic acids.     

Cobalt co-catalysis for cross-electrophile coupling: diarylmethanes from benzyl mesylates and aryl halides

The nickel-catalyzed cross-coupling of aryl halides with alkyl radicals derived from alkyl halides has recently been extended to couplings with carbon radicals generated by a co-catalyst. In this study, a new co-catalyst, cobalt phthalocyanine (Co(Pc)), is introduced and demonstrated to be effective for coupling substrates not prone to homolysis. This is because Co(Pc) reacts with electrophiles by an S_N2 mechanism instead of by the electron-transfer or halogen abstraction mechanisms previously explored. Studies demonstrating the orthogonal reactivity of (bpy)Ni and Co(Pc), applying this selectivity to the coupling of benzyl mesylates with aryl halides, and the adaptation of these conditions to the less reactive benzyl phosphate ester and an enantioconvergent reaction are presented.     

Reactions of hypervalent iodine reagents with palladium: mechanisms and applications in organic synthesis

The unique reactivity of hypervalent iodine reagents with Pd0 and PdII complexes has been exploited for a variety of synthetically useful organic transformations. For example, IIII reagents have been used in place of aryl halides for diverse Pd-catalyzed C-C and C-heteroatom bond-forming cross-coupling reactions. In addition, these reagents have found application in Pd-catalyzed oxidation reactions, including the oxidative functionalization of C-H bonds and the 1,2-aminooxygenation of olefinic substrates. This review discusses both the synthetic utility and the interesting mechanistic features of these transformations.