A general rhodium-catalyzed cross-coupling reaction of thiols with aryl iodides

The general procedure for the rhodium-catalyzed cross-coupling of thiols with aryl iodides is described. The catalytic system consists of 5 mol % of [RhCl(cod)]₂ and 10 mol % of PPh₃ as a ligand. A variety of aryl iodides reacted with thiols, giving aryl thioethers in good to excellent yields. It is important to note that the deactivated aryl iodides such as 4-iodoanisole is worked smoothly to provide the corresponding aryl thioethers in excellent yields. Functional groups such as free-amines, chloro, are all tolerated under the employed reaction conditions.     

Efficient copper-catalyzed coupling of aryl iodides and thiobenzoic acid

A highly efficient copper-catalyzed coupling reaction of aryl iodides and thiobenzoic acid, using 10 mol % of copper iodide, 20 mol % of 1,10-phenanthroline, and ⁱPr₂NEt in toluene, was developed. This methodology is applicable to a variety of aryl iodides.     

Direct synthesis of 3-arylindoles via annulation of aryl hydroxylamines with alkynes

3-Arylindoles are produced in moderate to excellent yields from the reaction between aryl hydroxylamines and alkynes catalyzed by 10 mol % iron(II) phthalocyanine [Fe(Pc)]. Terminal and internal alkynes afford 3-aryl substituted indoles exclusively. Electron-donating and -withdrawing groups are tolerated on the aryl hydroxylamine. A few bioactive indoles are synthesized as well as several new indoles using this one-step intermolecular annulation procedure.     

A practical and efficient procedure for the cleavage of acylals to aldehydes catalyzed by indium tribromide in water

Indium tribromide (10 mol %) is an efficient catalyst for chemoselective cleavage of aryl acylals in refluxing water. A variety of acylals have been deprotected to give the corresponding parent aldehydes in high yield. The procedure presented is operationally simple, practical, and compatible with other sensitive functionalities such as methoxy, methyleneioxy, and benzyloxy groups present in the substrates.     

Copper-catalyzed cross-coupling of aryl iodides and aryl acetylenes using microwave heating

An efficient copper-catalyzed cross-coupling of aryl iodides with aryl acetylenes under microwave irradiation is described. The reaction proceeds under microwave heating with 10 mol % CuI and 2 equiv Cs₂CO₃ in 43-87% yields.     

Palladium-catalyzed coupling of vinyl tosylates with arylsulfinate salts

The first palladium-catalyzed coupling of vinyl tosylates with arylsulfinate salts is described. A variety of cyclic and acyclic vinyl tosylates were coupled with aryl sulfinate salts using 2.5 mol % Pd₂(dba)₃/5.0 mol % XantPhos to give vinyl aryl sulfone products in good yields. The coupling was extended to the preparation of a cyclopropyl vinyl sulfone.     

Asymmetric Suzuki-Miyaura cross-coupling of aryl chlorides with enhancement of reaction time and catalyst turnover

A series of new chiral phosphonite ligands were evaluated for the palladium-catalyzed asymmetric Suzuki-Miyaura cross-coupling reactions of aryl chlorides. Ligand 4 gave 91% yield and 78% ee with 0.5 mol % catalyst loading for the coupling of aryl boronic acid and aryl chloride in 5 h. When the catalyst loading was lowered to 0.1 mol % the same reaction gave 75% yield and 76% ee.     

One-pot synthesis of 1,4-diarylsubstituted 1,3-diynes from the sequential coupling reactions of aryl iodides and propiolic acid

1,4-Disubstituted 1,3-dialkynes were obtained from the one-pot palladium/copper-catalyzed coupling reactions of aryl iodide and propiolic acid. The optimized catalytic system consisted of 5.0 mol % Pd(PPh₃)₂Cl₂, 10 mol % dppb, 10 mol % CuI, 2.4 equiv of DBU, and 1.2 equiv of K₂CO₃. The coupling reaction was carried out at 30 °C for 6 h and subsequently at 80 °C for 3 h.     

Rhodium-catalyzed organothio exchange reaction of α-organothioketones with disulfides

RhH(PPh(3))(4) and 1,2-bis(diphenylphosphino)ethane (dppe) catalyzed the organothio exchange reaction of α-organothioketones and organic disulfides. The reaction was affected by the structure of the substrate: α-phenylthio and α-alkylthio aryl ketones reacted effectively with diaryl and dialkyl disulfides; α-phenylthio dialkyl ketones reacted with diaryl disulfides but not with dialkyl disulfides; diaryl disulfides with electron-donating p-substituents were more reactive than those with electron-withdrawing p-substituents.     

Copper-catalyzed cross-coupling of sulfonamides with aryl iodides and bromides facilitated by amino acid ligands

A highly general, convenient, and inexpensive catalyst system was developed for the N-arylation of sulfonamides with aryl iodides or bromides by using 5-20 mol % of CuI as catalyst, 20 mol % of N-methylglycine (for aryl iodides) or N,N-dimethylglycine (for aryl bromides) as ligand, and K₃PO₄ as base.     

Palladium(II) chloride/EDTA-catalyzed biaryl homo-coupling of aryl halides in aqueous medium in the presence of ascorbic acid

Both electron-deficient and electron-rich aryl bromides undergo biaryl homo-coupling in a basic aqueous-ethanolic medium in the presence of PdCl₂-EDTA (1:1 molar ratio, 3 mol %) as catalyst and ascorbic acid as reductant (1 mol equiv) in acceptable to good yields.     

Design and synthesis of thioether-imidazolium chlorides as efficient ligands for palladium-catalyzed Suzuki-Miyaura coupling of aryl bromides with arylboronic acids

The catalyst composed of 0.25-0.025 mol % of [Pd(allyl)Cl]₂ and 0.5-0.05 mol % of the thioether-imidazolium chloride 3c was proven to be efficient in the Suzuki-Miyaura cross-coupling reactions of aryl bromides with arylboronic acids.     

Palladium-catalyzed cross-coupling of trimethoxysilylbenzene with aryl bromides and chlorides using phosphite ligands

Phosphites were employed as ligands in palladium-catalyzed Hiyama coupling reactions. The optimized reaction conditions were equimolar amounts (5 mol % each) of Pd(acac)₂ and phosphite 1 in p-xylene at 80 °C with TBAF as an additive. This catalyst system exhibited high activities in the reactions with trimethoxysilylbenzene and aryl bromides that have electron-donating or electron-withdrawing groups. In the case of aryl chlorides, substrates possessing electron-withdrawing groups gave the coupled products in high yields.     

InBr3-catalyzed annulations of cyclic 1,3-diketones with aryl propargyl alcohols: a novel synthesis of 2,4-diaryldihydropyrans

The cyclic 1,3-dicarbonyl compounds undergo smooth cyclization with aryl propargyl alcohols in the presence of 10 mol % indium tribromide in refluxing dichloroethane to produce 2,4-diarylpyran derivatives in good yields with high selectivity.     

A copper- and amine-free Sonogashira coupling reaction promoted by a ferrocene-based phosphinimine-phosphine ligand at low catalyst loading

A palladium(II) complex containing a ferrocene-based phosphinimine-phosphine ligand was applied to the amine- and copper-free Sonogashira coupling of aryl iodides and aryl bromides with terminal alkynes using 1 equiv of tetrabutylammonium acetate as an activator. The corresponding disubstituted alkynes were obtained in high yields and TONs using 0.1 mol % Pd-catalyst.     

Copper-catalyzed decarboxylative coupling reactions for the synthesis of propargyl amines

When aryl alkynyl carboxylic acids were allowed to react with amines and aldehydes in CH₃CN at 80 °C in the presence of 10 mol % CuI, the desired propargyl amines were formed in good yields. This coupling reaction demonstrated to work across a broad range of reagents including functionalized aryl alkynyl carboxylic acids, aliphatic and aromatic aldehydes, and cyclic and acyclic amines.     

A novel class of amide-derived air-stable P,O-ligands for Suzuki cross-coupling at low catalyst loading

The benzamide-derived P,O-ligands efficiently promoted the Pd-catalyzed Suzuki cross-coupling reactions of aryl bromides with phenylboronic acid at 0.01 mol % of Pd loading at 60-80 °C to form biaryls in excellent yields. A sterically hindered arylboronic acid gave a quantitative yield of the coupling product at 110 °C with 1 mol % Pd.     

Hydroxymethylation of α-substituted nitroacetates

Only 1 mol % of K₃PO₄ is efficient enough to catalyze the hydroxymethylation of α-substituted nitroacetates in good to excellent yield. Both aliphatic and aryl substituted nitroacetates work well under this reaction. The first catalytic asymmetric version of this reaction also reported that 10 mol % of cupreidine could catalyze this reaction up to 71% ee and 89% yield. Paraformaldehyde and formalin could both serve as the hydroxymethylation C1 unit. The synthetic application of products is also demonstrated.     

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.     

Preparation of 2,2-difluoro-1-trialkylsilylethenylstannanes and their cross-coupling reactions

Reaction of 2 with bis(tributyltin) in the presence of 3 mol % Pd₂(dba)₃, 6 mol % XPhos, and 30 equiv of LiBr in wet and air bubbled THF at reflux for 8 h afforded the desired products 3 in 73–74% yields. The cross-coupling reaction of 3a with aryl iodides in the presence of 10 mol % Pd(PPh₃)₄ and 10 mol % CuI afforded the coupled products 4a–p in 47–90% yields. The coupling reaction of 3b with various alkynyl bromides having aryl-, alkyl, or trialkylsilyl group also afforded the corresponding 1,3-enynes 5a–g in 61–77% yields.