Intra‐ and Intermolecular Nickel‐Catalyzed Reductive Cross‐Electrophile Coupling Reactions of Benzylic Esters with Aryl Halides

Nickel‐catalyzed cross‐electrophile coupling reactions of benzylic esters and aryl halides have been developed. Both inter‐ and intramolecular variants proceed under mild reaction conditions. A range of heterocycles and functional groups are tolerated under the reaction conditions. Additionally, the first example of a stereospecific cross‐electrophile coupling of a secondary benzylic ester is described.     

Ketone synthesis under neutral conditions. Cu(I) diphenylphosphinate-mediated,palladium-catalyzed coupling of thiol esters and organostannanes

[reaction: see text] A versatile approach to ketone synthesis is described. The reaction relies on the palladium-catalyzed, copper diphenylphosphinate-mediated coupling of thiol esters with organostannanes under neutral reaction conditions. This reaction complements the previously described coupling of thiol esters with boronic acids that used dual thiophilic-borophilic activation methodology.     

Regiospecific formation of 1,3-dienes by the palladium catalysed intra- and inter-molecular coupling of vinyl halides.1

Palladium acetate (5 mol %) effects catalytic inter-and intra-molecular coupling of vinyl bromides in good yield under mild conditions provided sufficient triarylphosphine and potassium carbonate are present to regenerate the active palladium(O) species. Wilkinson's catalyst is a poor catalyst for the same coupling reaction. Double bond isomerisation is not observed under these conditions. The palladium catalyst also couples iodobenzene to biphenyl in 48% yield whilst Wilkinson's catalyst is ineffective. The mechanism of the coupling process is discussed.     

Formation of arylboronates by a CuI-catalyzed coupling reaction of pinacolborane with aryl iodides at room temperature

[reaction: see text] The coupling reaction of pinacolborane with aryl iodides under the catalysis of 10 mol % CuI and the action of sodium hydride in THF works at room temperature to provide corresponding arylboronates in good yields. Aryl bromides give poor conversion under these reaction conditions.     

Photoinduced switching from living radical polymerization to a radical coupling reaction mediated by organotellurium compounds

An efficient and simple method for the synthesis of symmetric macromolecules by photoinduced switching from radical polymerization to a radical coupling reaction is reported. Structurally well-defined telechelic polyisoprenes and ABA-triblock copolymers were prepared by successive organotellurium-mediated living radical polymerization (TERP) under thermal conditions, followed by a polymer-end radical coupling reaction under photoirradiation.     

Mesoporous Silica MCM‐41 Supported N‐Heterocyclic Carbene‐Pd Complex for Heck and Sonogashira Coupling Reactions

Heterocyclic carbene‐Pd complex was anchored onto the mesoporous silica MCM‐41 which exhibits high catalytic activity in Heck reaction under phosphine free reaction conditions for the reaction of iodo/bromoarenes with olefinic compounds such as butyl acrylate, isopropyl acrylate and styrene. This catalytic system also showed high activity for Sonogashira coupling reaction of various aryl halides under copper, phosphine and solvent‐free reaction conditions. The air and thermally stable catalyst were reused several times without significant loss of its activity. High efficiency of the catalyst along with its recycling ability and the rather low Pd‐loading demonstrated in both Heck and Sonogashira coupling reactions are the merits of the presented catalyst system.     

Reaction mechanism in the mechanochemical synthesis of dibenzophenazine: application of vibronic coupling density analysis

The reaction mechanism for mechanochemical synthesis of dibenzophenazine was theoretically investigated in terms of the vibronic coupling density, which describes the interactions between electrons and nuclear motions. The concept theoretically indicates experimentally observed reactive sites that cannot be explained by the conventional frontier orbital theory. The results of vibronic coupling density analysis suggested the difference between reaction mechanisms under thermal and mechanochemical conditions.     

原位生成的水溶性Salen-Pd配合物催化微波促进水中的C-C偶联反应

将一种水溶性Salen,N,N’-双[（5-磺酸基-2-羟基）苄基]缩N,N’-二甲基-1,2-乙二胺（L）与醋酸钯原位生成水溶性Salen-Pd配合物,该水溶性钯配合物应用于催化微波加热的水中的Heck和Sonogashira碳-碳偶联反应.在优化反应条件之后,对溴苯衍生物与乙烯衍生物的Heck偶联反应以及溴苯衍生物与苯乙炔及其衍生物之间的Sonogashira偶联反应进行了考察.发现,在优化的反应条件下,无论是Heck反应,还是Sonogashira偶联反应,都能得到很好的收率.在有机物分离之后,水相继续循环使用4次,在水相的前3次循环使用时,都获得了不错的收率.     

Thio-mediated two-component coupling reaction of carboxylic acids and isonitriles under mild conditions

The coupling reaction between carboxylic acids and isonitriles in the presence of thiophenol as activator under mild conditions is described.     

A new tandem reaction of benzyne: one-pot synthesis of aryl amines containing anthracene

[reaction: see text] The reaction of benzyne with N-substituted imidazoles affords a novel way to prepare arylamines containing anthracene under very mild conditions. This transformation is assumed to proceed via a tandem reaction involving a Diels-Alder reaction and an intermolecular nucleophilic coupling reaction.     

Synthesis of Aryldiazoacetates through Palladium(0)‐Catalyzed Deacylative Cross‐Coupling of Aryl Iodides with Acyldiazoacetates

Palladium(0)‐catalyzed deacylative cross‐coupling of aryl iodides and acyldiazocarbonyl compounds can be achieved at room temperature under mild reaction conditions. The coupling reaction represents a highly efficient and general method for the synthesis of aryldiazocarbonyl compounds, which have found wide and increasing applications as precursors for generating donor/acceptor‐substituted metallocarbenes.     

Hypervalent Iodine Reagents Enable Chemoselective Deboronative/Decarboxylative Alkenylation by Photoredox Catalysis

Chemoselective C(sp³)? C(sp²) coupling reactions under mild reaction conditions are useful for synthesizing alkyl‐substituted alkenes having sensitive functional groups. Reported here is a visible‐light‐induced chemoselective alkenylation through a deboronation/decarboxylation sequence under neutral aqueous reaction conditions at room temperature. This reaction represents the first hypervalent‐iodine‐enabled radical decarboxylative alkenylation reaction, and a novel benziodoxole‐vinyl carboxylic acid reaction intermediate was isolated. This C(sp³)? C(sp²) coupling reaction leads to aryl‐and acyl‐substituted alkenes containing various sensitive functional groups. The excellent chemoselectivity, stable reactants, and neutral aqueous reaction conditions of the reaction suggest future biomolecule applications.     

Molecular Iodine: An Efficient Catalyst for the Synthesis of Tetrahydrobenzo[b]pyrans

An iodine/DMSO system is introduced as an excellent catalyst in three‐component coupling reactions of tetrahydrobenzo[b]pyran synthesis. The reaction proceeds quickly under very mild reaction conditions.     

An efficient BINAM-copper(II) catalyzed Ullmann-type synthesis of diaryl ethers

A wide range of diaryl ethers are synthesized from the corresponding aryl iodides and phenols through Ullmann type coupling reactions in the presence of a catalytic amount of easily available BINAM-Cu(OTf)₂ complex under mild reaction conditions. Less reactive aryl bromides have also been shown to react with phenols under identical reaction conditions to give good yields of the diaryl ethers without increasing the reaction temperature and time.     

Short communication: Stille coupling reactions of functionalized triorganotin halides

Convenient conditions for the Stille coupling of halide‐bearing triorganotin compounds, which do not normally react under typical Stille reaction conditions, are presented. The coupling of vinylstannanes with allyl bromide using palladium(II) catalysis is accomplished under fluoride assistance to give the substituted 2,5‐hexadien‐1‐ols in Z‐configuration. Copyright © 2004 John Wiley & Sons, Ltd.     

Copper-catalyzed N-arylation of sulfonamides with aryl bromides under mild conditions

This Letter describes a copper catalyzed sulfonamide coupling reaction with aryl bromides to form N-aryl sulfonamides under mild conditions, including the first examples of Cu-catalyzed sulfonamide coupling at room temperature. The reaction protocol tolerates a broad range of substrates including a variety of primary and secondary sulfonamides and challenging heteroaryl bromides such as 2-bromothiazole.     

Elaboration of 2-(trifluoromethyl)indoles via a cascade coupling/condensation/deacylation process

CuI/l-proline-catalyzed coupling of 2-halotrifluoroacetanilides with beta-keto esters in anhydrous DMSO under the action of Cs2CO3 at 40-80 degrees C produces polysubstituted 2-(trifluoromethyl)indoles in good to excellent yields. This reaction is suggested to occur via a novel coupling/condensation/deacylation mechanism, and many functional groups are tolerated under these conditions.     

A new ketone synthesis by palladium-catalyzed cross-coupling reactions of esters with organoboron compounds

[reaction: see text] The palladium-catalyzed coupling reaction of 2-pyridyl esters with organoboron compounds is described. The reaction is compatible with various functional groups and proceeds under mild reaction conditions. The coordination of the nitrogen atom to Pd is a key step for efficient reaction.     

Polyaniline‐Induced CH Arylation of Arenes with Arenediazonium Salts

A reduced form of polyaniline has been shown to induce direct arylation of an arenediazonium salt with an arene (Gomberg–Bachmann reaction) to give the cross‐coupling product in moderate to good yields under mild conditions. Various arenediazonium salts and arenes, including heteroarenes such as furans, thiophenes, and pyrroles, are employed for the reaction. The most favorable combination of substrates is an electron‐poor arenediazonium salt with an electron‐rich heteroarene. Investigation of the mechanism by reactions with radical scavengers and experiments on kinetic isotope effects indicated the occurrence of a radical chain reaction initiated by one‐electron reduction of an arenediazonium salt by the polyaniline. Only 1 mol % (based on aniline tetramer) of the polyaniline is required for the cross‐coupling reaction to occur. This reaction proceeds under metal‐free conditions and with no need for photonic activation.     

AlCl3-mediated direct carbon-carbon bond-forming reaction of alpha-hydroxyketene-S,S-acetals with arenes and synthesis of 3,4-disubstituted dihydrocoumarin derivatives

A simple and efficient AlCl(3)-mediated C-C coupling reaction between readily available alpha-hydroxyketene-S,S-acetals and various arenes via direct substitution of the hydroxy group in alcohols has been developed. On the basis of this C-C coupling reaction, a series of bio- and pharmacologically important 3,4-disubstituted dihydrocoumarins, difficult to obtain by other methods, were prepared in high yields by a sequential Friedel-Crafts alkylation and intramolecular annulation reaction of alpha-hydroxyketene acyclic-S,S-acetals with phenols under mild conditions.