Betti Base as an Efficient Ligand for Copper-Catalyzed Ullmann Coupling of Phenol with Aryl Halides

A simple, general, and highly efficient Betti base ligand has been developed for copper-catalyzed Ullmann coupling of phenol with aryl halides without the protection of an inert atmosphere. The reaction proceeds smoothly in the presence of K₂CO₃ as the base and dimethylsulfoxide as the solvent. The catalyst was reused several times with no evident loss of catalytic activity and is environmentally friendly.     

Copper‐Catalyzed Synthesis of Triarylamines from Aryl Halides and Arylamines

A simple and efficient methodology for the synthesis of triphenylamines has been demonstrated using copper catalyst with a ligand and tripotassium phosphate as the base. The effect of parameters such as catalyst precursors, ligands, bases and solvents were studied and a series of triphenylamines were obtained with moderate to excellent yields in DMF. This reaction displays great functional groups compatibility in the presence of a broad range of functional groups.     

Synthesis of Highly Functionalized Diaryl Ethers by Copper‐Mediated O‐Arylation of Phenols using Trivalent Arylbismuth Reagents

Highly functionalized diaryl ethers were prepared by copper(II) acetate mediated O‐arylation reaction of phenols using trivalent organobismuthanes. The reaction is performed under simple conditions and tolerates a wide diversity of functional groups on the phenol and on the organobismuth reagent. Substoichiometric amounts of catalyst can be used by performing the reaction under an oxygen atmosphere. The N‐arylation of pyridones is also reported.     

Copper‐Catalyzed Regioselective Borocarbonylative Coupling of Unactivated Alkenes with Alkyl Halides: Synthesis of β‐Boryl Ketones

The borocarbonylative coupling of unactivated alkenes with alkyl halides remains a challenge. In this communication, a Cu‐catalyzed borocarbonylative coupling of unactivated alkenes with alkyl halides for the synthesis of β‐boryl ketones has been developed. A broad range of β‐boryl ketone derivatives was prepared in moderate to excellent yields with complete regioselectivity.     

Copper‐catalyzed N‐Arylation of Imidazoles with Aryl or Heteroaryl Halides Facilitated by Dimethylglyoxime in Water

A combination of CuSO₄/dimethylglyoxime was found to be an efficient and inexpensive catalyst system for N‐arylation of imidazole and benzimidazole with aryl halides and heteroaryl halides in water, providing the corresponding products in moderate to good yields.     

A Catalyst‐Controlled Aerobic Coupling of ortho‐Quinones and Phenols Applied to the Synthesis of Aryl Ethers

ortho‐Quinones are underutilized six‐carbon‐atom building blocks. We herein describe an approach for controlling their reactivity with copper that gives rise to a catalytic aerobic cross‐coupling with phenols. The resulting aryl ethers are generated in high yield across a broad substrate scope under mild conditions. This method represents a unique example where the covalent modification of an ortho‐quinone is catalyzed by a transition metal, creating new opportunities for their utilization in synthesis.     

Dialkylzinc‐Mediated Cross‐Coupling Reactions of Perfluoroalkyl and Perfluoroaryl Halides with Aryl Halides

A highly chemoselective perfluoroalkylation reaction of aromatic halides is reported. Thermally stable perfluoroalkylzinc reagents, generated by a rapid halogen–zinc exchange reaction between diorganozinc and perfluoroalkyl halide species, couple with a wide range of aryl halides in the presence of a copper catalyst, in moderate to high yields. Good stability of the perfluoroalkylzinc species was indicated by DFT calculation and the reagents were storable for at least three months under argon without loss of activity. This method is applicable to gram‐scale synthesis, and its functional group tolerance compares favorably with reported protocols.     

Efficient Copper(I)‐Catalyzed S‐Arylation of KSCN with Aryl Halides in PEG‐400

A simple and efficient protocol for CuI‐catalyzed C? S bond formation of aryl halides with KSCN to symmetrical diaryl sulfides was reported in PEG‐400 without any other additives. A variety of aryl halides were converted to the corresponding diaryl sulfides in good to excellent yields. The present procedure tolerated a variety of functional groups and the steric hindrance of ortho‐substituents on aryl halides did not affect the outcome.     

Copper‐Catalyzed Coupling of Triaryl‐ and Trialkylindium Reagents with Aryl Iodides and Bromides through Consecutive Transmetalations

An efficient copper(I)‐catalyzed coupling of triaryl and trialkylindium reagents with aryl iodides and bromides is reported. The reaction proceeds at low catalyst loadings (2 mol %) and generally only requires 0.33 equivalents of the triorganoindium reagent with respect to the aryl halide as all three organic nucleophilic moieties of the reagent are transferred to the products through consecutive transmetalations. The reaction tolerates a variety of functional groups and sterically hindered substrates. Furthermore, preliminary mechanistic studies that entailed the synthesis and characterization of potential reaction intermediates offered a glimpse of the elementary steps that constitute the catalytic cycle.     

Copper‐Catalyzed Reductive Cross‐Coupling of Nonactivated Alkyl Tosylates and Mesylates with Alkyl and Aryl Bromides

A copper‐catalyzed reductive cross‐coupling reaction of nonactivated alkyl tosylates and mesylates with alkyl and aryl bromides was developed. It provides a practical method for efficient and cost‐effective construction of aryl–alkyl and alkyl–alkyl C?C bonds with stereocontrol from readily available substrates. When used in an intramolecular fashion, the reaction enables convenient access to various substituted carbo‐ or heterocycles, such as 2,3‐dihydrobenzofuran and benzochromene derivatives.     

Picolinamides as Effective Ligands for Copper‐Catalysed Aryl Ether Formation: Structure–Activity Relationships,Substrate Scope and Mechanistic Investigations

The use of picolinic acid amide derivatives as an effective family of bidentate ligands for copper‐catalysed aryl ether synthesis is reported. A fluorine‐substituted ligand gave good results in the synthesis of a wide range of aryl ethers. Even bulky phenols, known to be very challenging substrates, were shown to react with aryl iodides with excellent yields using these ligands. At the end of the reaction, the first examples of end‐of‐life Cu species were isolated and identified as Cu^II complexes with several of the anionic ligands tested. A preliminary mechanistic investigation is reported that suggests that the substituents on the ligands might have a crucial role in determining the redox properties of the metal centre and, consequently, its efficacy in the coupling process. An understanding of these effects is important for the development of new efficient and tunable ligands for copper‐based chemistry.     

Copper‐Catalyzed Cross‐Coupling of Boronic Esters with Aryl Iodides and Application to the Carboboration of Alkynes and Allenes

Copper‐catalyzed Suzuki–Miyaura‐type cross‐coupling and carboboration processes are reported. The cross‐couplings function well with a variety of substituted aryl iodides and aryl boronic esters and allows for orthogonal reactivity compared to palladium‐catalyzed processes. The carboboration method includes both alkynes and allenes and provides access to highly substituted and stereodefined vinyl boronic esters. The alkyne carboboration method is highlighted in the simple one‐pot synthesis of Tamoxifen.