Ligand-supported palladium-catalyzed cross-coupling reactions of (hetero) aryl chlorides

The introduction of electron rich and sterically hindered ligands has made otherwise inert aryl chlorides and hetero aryl chlorides viable coupling partners in palladium-catalyzed Suzuki-Miyaura, Sonogashira, Stille and other types of cross-coupling reactions. This review gives highlights of cross-coupling of aryl chlorides employing in situ generated palladium catalytic systems.     

Suzuki-Miyaura coupling reaction of aryl chlorides using di(2,6-dimethylmorpholino)phenylphosphine as ligand

Suzuki-Miyaura coupling was achieved on a variety of aryl chlorides by using di(2,6-dimethylmorpholino)phenylphosphine (L1) as a bulky electron-rich monoaryl phosphine ligand. We report the couplings of various chlorobenzenes and heteroaryl chlorides.     

Efficient palladium-catalyzed amination of aryl chlorides using di(dicyclohexylamino)phenylphosphine as a PN2 ligand

The palladium-catalyzed amination of a variety of aryl chlorides has been accomplished by using di(dicyclohexylamino)phenylphosphine (1) as a bulky electron-rich monoaryl phosphine ligand. The optimized condition for the palladium-catalyzed amination of aryl chloride is the followings: aniline (3.0 mmol, 1.0 equiv), chlorobenzene (3.15 mmol, 1.05 equiv), ligand 1 (1 mol %, 0.03 mmol), KO^tBu (4.5 mmol, 1.5 equiv), Pd₂(dba)₃ (1 mol %, 0.03 mmol), and toluene as solvent at reflux temperature. We report on couplings of various amines or chloroamines with chlorobenzenes and heteroaryl chloride.     

Synthesis of aryl acetamides by aminocarbonylation of benzylic chlorides using carbamoylsilane as an amide source

Using N-methyl-N-(1-phenyl)ethylcarbamoyl(trimethyl)silane as an amide source, the direct transformation of benzylic chlorides into the corresponding aryl acetamides through palladium-catalyzed aminocarbonylation is described. The electronic property and the relative position of substituents on the aromatic ring impact the coupling efficiency.     

Copper-catalyzed direct preparation of diaryl sulfides from aryl iodides using potassium thiocyanate as a sulfur transfer reagent

A method for direct preparation of diaryl sulfides from aryl iodides using potassium thiocyanate as a sulfur-transfer agent is reported. A catalyst system comprising of a simple copper salt, tetrabutylammonium bromide as a phase-transfer agent and water as the solvent is used. Microwave heating at 200 °C for 60 min allows for the conversion of a range of aryl iodides to the corresponding diaryl sulfides.     

Porous polymeric ligand promoted copper-catalyzed C-N coupling of(hetero)aryl chlorides under visible-light irradiation

A porous polymeric ligand(PPL)has been synthesized and complexed with copper to generate a heterogeneous catalyst(Cu@PPL)that has facilitated the efficient C-N coupling with various(hetero)aryl chlorides under mild conditions of visiblelight irradiation at 80°C(58 examples,up to 99%yields).This method could be applied to both aqueous ammonia and substituted amines,and is compatible to a variety of functional groups and heterocycles,as well as allows tandem C-N couplings with conjunctive dihalides.Furthermore,the heterogeneous characteristic of Cu@PPL has enabled a straightforward catalyst separation in multiple times of recycling with negligible catalytic efficiency loss by simple filtration,affording reaction mixtures containing less than 1 ppm of Cu residue.     

Efficient Suzuki-Miyaura coupling of (hetero)aryl chlorides with thiophene- and furanboronic acids in aqueous n-butanol

An efficient Suzuki cross-coupling protocol enables the reaction of N-hetero and normal aryl chlorides with thiophene- and furanboronic acids. Coupling is effected in aqueous n-butanol as the solvent in near quantitative yield with a catalyst loading of 0.1-1 mol %. For heterocyclic substrates aqueous catalysis is found to be more efficient than Suzuki coupling under anhydrous conditions. The developed Suzuki coupling procedure utilizes biodegradable solvents and is useful for large scale reactions, as it includes the facile product separation from a biphasic solvent mixture without the need for additional organic solvents during workup.     

Rational and predictable chemoselective synthesis of oligoamines via Buchwald-Hartwig amination of (hetero)aryl chlorides employing Mor-DalPhos

We report a diverse demonstration of synthetically useful chemoselectivity in the synthesis of di-, tri-, and tetraamines (62 examples) by use of Buchwald-Hartwig amination employing a single catalyst system ([Pd(cinnamyl)Cl](2)/L1; L1 = N-(2-(di(1-adamantyl)phosphino)phenyl)morpholine, Mor-DalPhos). Competition reactions established the following relative preference of this catalyst system for amine coupling partners: linear primary alkylamines and imines > unhindered electron-rich primary anilines, primary hydrazones, N,N-dialkylhydrazines, and cyclic primary alkylamines > unhindered electron-deficient primary anilines, α-branched acyclic primary alkylamines, hindered electron-rich primary anilines ? cyclic and acyclic secondary dialkylamines, secondary alkyl/aryl and diarylamines, α,α-branched primary alkylamines, and primary amides. The new isomeric ligand N-(4-(di(1-adamantyl)phosphino)phenyl)morpholine (p-Mor-DalPhos, L2) was prepared in 63% yield and was crystallographically characterized; the [Pd(cinnamyl)Cl](2)/L2 catalyst system exhibited divergent reactivity. Application of the reactivity trends established for [Pd(cinnamyl)Cl](2)/L1 toward the chemoselective synthesis of di-, tri-, and tetraamines was achieved. Preferential arylation was observed at the primary alkylamine position within 2-(4-aminophenyl)ethylamine with [Pd(cinnamyl)Cl](2)/L1 and 4-chlorotoluene (affording 5a); the alternative regioisomer (5a') was obtained when using [Pd(cinnamyl)Cl](2)/L2. These observations are in keeping with coordination chemistry studies, whereby binding of 2-(4-aminophenyl)ethylamine to the in situ generated [(L1)Pd(p-tolyl)](+) fragment occurred via the primary amine moiety, affording the crystallographically characterized adduct [(L1)Pd(p-tolyl)(NH(2)CH(2)CH(2)(4-C(6)H(4)NH(2))](+)OTf(-) (7) in 72% yield.     

Redox-triggered hydroarylation of o-(hydroxyalkyl)arylalkynes with arylsulfonyl chlorides using visible light catalysis

A new radical-mediated method for the synthesis of 1-(2-(1,2-diarylvinyl)phenyl)ethan-1-ones by the redox hydroarylation of o-(hydroxyalkyl)arylalkynes with arylsulfonyl chlorides is described. This visible light catalysis method proceeds via a sequence of the radical addition of aryl group across the C-C triple bond, protonation and redox reaction, and represents a new redox transformation reaction directed by a neighboring hydroxyl group.     

Synthesis of aryl(di)azinyl ketones through copper- and iron-catalyzed oxidation of the methylene group of aryl(di)azinylmethanes

Sustainable Oxidations: an oxidation method to transform aryl(di)azinylmethanes into aryl(di)azinyl ketones is described. Base metals (copper and iron) as catalysts in combination with O(2) as the oxidant are used, which makes this method sustainable. The utility of this method is illustrated by the synthesis of 6-(4-methylbenzoyl)pyridine-2-carbaldehyde, which is an intermediate in the preparation of the drug Acrivastine.     

Cobalt-catalyzed aminocarbonylation of (hetero)aryl halides promoted by visible light

The catalytic aminocarbonylation of (hetero)aryl halides is widely applied in the synthesis of amides but relies heavily on the use of precious metal catalysis. Herein, we report an aminocarbonylation of (hetero)aryl halides using a simple cobalt catalyst under visible light irradiation. The reaction extends to the use of (hetero)aryl chlorides and is successful with a broad range of amine nucleophiles. Mechanistic investigations are consistent with a reaction proceeding via intermolecular charge transfer involving a donor–acceptor complex of the substrate and cobaltate catalyst.

An aminocarbonylation of (hetero)aryl halides using a simple cobalt catalyst under visible light irradiation is presented.     

Synthesis of 2-trifluoromethyl-1(substituted aryl)-4(1H)-quinolones using trifluoroacetamidoyl chlorides

A simple two-step procedure for the preparation of 2-trifluoromethyl-1(substituted aryl)-4(1H)-quinolones utilizing electrophilic trifluoroacetamidoyl chlorides as the starting materials is described. The cyclization of trifluoromethyl enaminone intermediates with potassium carbonate in hot dimethylformamide produce the trifluoromethylated 4(1H)-quinolones in good to excellent yields.     

First Synthesis of Bis(di(indolyl)aryl)methanes From Bis(salicylaldehydes)

In this article, a simple method for the synthesis of bis(di(indolyl)aryl)methanes is described. The iodine‐catalyzed (5 mol %) reaction of indoles with various bis(salicylaldehyde) derivatives affords the bis(di(indolyl)aryl)methanes in excellent yields. The reaction works well under mild reaction condition with shorter reaction time.     

应用亲核性离子交换树脂(PhS^-型)制备苯硫醚

用强碱性离子交换树脂(^-OH型)与PhSH反应，得到一种离子交换树脂支载的PhS^-试剂，它与卤代物和α,β-不饱和醛酮很容易反应，得到相应的苯硫醚，产率较高或中等。     

Metal Free Bi(hetero)aryl Synthesis: A Benzyne Truce–Smiles Rearrangement

A new benzyne transformation is described that affords versatile biaryl structures without recourse to transition‐metal catalysis or stoichiometric amounts of organometallic building blocks. Aryl sulfonamides add to benzyne upon fluoride activation, and then undergo an aryl Truce–Smiles rearrangement to afford biaryls with sulfur dioxide extrusion. The reaction proceeds under simple reaction conditions and has excellent scope for the synthesis of sterically hindered atropisomeric biaryl amines.     

A short synthesis of 3,3-di(hetero)arylpropylamines obtained from bis-(hetero)aryl ketones via palladium catalysis

A palladium-catalyzed parallel synthesis of bis-hetero(aryl) ketones is described with two further synthetic steps allowing easy entry to 3,3-di(hetero)arylpropylamines.     

Pd-catalyzed decarboxylative cross-coupling of sodium pyrimidinecarboxylates with (hetero)aryl bromides

A straightforward method for the synthesis of functionalized 4- or 5-(hetero)arylpyrimidines via decarboxylative cross-coupling reaction from readily available pyrimidine-4- and pyrimidine-5-carboxylates was described. In the presence of dual-catalyst system of Pd(PPh₃)₄/Cu₂O, the reaction proceeds smoothly, tolerates a variety of functional groups, and provides easy access to the synthesis of different (hetero)arylpyrimidines compounds.