Chan–Lam coupling reactions: synthesis of heterocycles

Copper(ii)-catalyzed Chan–Lam cross-coupling: chemoselective N-arylation of aminophenols

Copper(ii)-catalyzed boronic acid promoted chemoselective N-arylation of unprotected aminophenols has been developed.

Palladium-catalyzed, unsymmetrical homocoupling of thiophenes via carbon–sulfur bond activation: a new avenue to homocoupling reactions

Introduction of an unprecedented pattern of reactivity, namely the C–N unsymmetrical homocoupling by joining the electrophilic and nucleophilic motifs of the substrate through transition-metal catalysis.

Sulfonato-imino copper(ii) complexes: fast and general Chan–Evans–Lam coupling of amines and anilines

A simple coordination complex allows Chans–Evans–Lam arylations of a wide variety of amines and anilines without optimization of reaction conditions.

Copper-Catalyzed Amidation of Primary and Secondary Alkyl Boronic Esters

The oxidative copper-catalyzed cross-coupling of functionalized alkyl boronic esters with primary amides is reported. Through the identification of appropriate diketimine ligands, conditions for efficient coupling of both primary and secondary alkyl boronic esters with diverse primary amides, including acetamide, have been developed.

Catalytic Chan-Lam coupling using a 'tube-in-tube' reactor to deliver molecular oxygen as an oxidant

A flow system to perform Chan–Lam coupling reactions of various amines and arylboronic acids has been realised employing molecular oxygen as an oxidant for the re-oxidation of the copper catalyst enabling a catalytic process. A tube-in-tube gas reactor has been used to simplify the delivery of the oxygen accelerating the optimisation phase and allowing easy access to elevated pressures. A small exemplification library of heteroaromatic products has been prepared and the process has been shown to be robust over extended reaction times.

Nickel-catalyzed Chan–Lam cross-coupling: chemoselective N-arylation of 2-aminobenzimidazoles

A complementary set of Ni- and Cu-based catalyst systems for the chemoselective N-arylation of 2-aminobenzimidazoles have been developed.

A new series of pyrenyl-based triarylamines: syntheses, structures, optical properties, electrochemistry and electroluminescence

A new series of pyrenyl-based triarylamines (2a–2e and 3py) were designed and synthesized. These pyrene-based triarylamines exhibit excellent photoelectric properties and are potentially functional materials for devices.

Iodine-catalyzed expeditious synthesis of sulfonamides from sulfonyl hydrazides and amines

A new synthesis of sulfonamides via an iodine-catalyzed sulfonylation of amines with arylsulfonyl hydrazides at room temperature is reported.

A highly efficient heterogeneous copper-catalyzed Chan–Lam coupling reaction of sulfonyl azides with arylboronic acids leading to N-arylsulfonamides

A highly efficient and practical method for the synthesis of N-arylsulfonamides has been developed by a heterogeneous copper-catalyzed Chan–Lam coupling between sulfonyl azides and boronic acids.

A quick Chan–Lam C–N and C–S cross coupling at room temperature in the presence of square pyramidal [Cu(DMAP)4I]I as a catalyst

A rapid and efficient protocol for C–N and C–S cross coupling has been developed using a new square pyramidal copper complex, [Cu(DMAP)₄I]I.

Copper-mediated synthesis of N-alkenyl-α,β-unsaturated nitrones and their conversion to tri- and tetrasubstituted pyridines

A Chan–Lam reaction has been used to prepare N-alkenyl-α,β-unsaturated nitrones, which undergo a subsequent thermal rearrangement to the corresponding tri- and tetrasubstituted pyridines. The optimization and scope of these transformations is discussed. Initial mechanistic experiments suggest a reaction pathway involving oxygen transfer followed by cyclization.

Branch-Selective Alkene Hydroarylation by Cooperative Destabilization: Iridium-Catalyzed ortho-Alkylation of Acetanilides

An iridium(I) catalyst system, modified with the wide-bite-angle and electron-deficient bisphosphine d(F) ppb (1,4-bis(di(pentafluorophenyl)phosphino)butane) promotes highly branch-selective hydroarylation reactions between diverse acetanilides and aryl- or alkyl-substituted alkenes. This provides direct and ortho-selective access to synthetically challenging anilines, and addresses long-standing issues associated with related Friedel-Crafts alkylations.

Formal Direct Cross-Coupling of Phenols with Amines

The transition-metal-catalyzed amination of aryl halides has been the most powerful method for the formation of aryl amines over the past decades. Phenols are regarded as ideal alternatives to aryl halides as coupling partners in cross-couplings. An efficient palladium-catalyzed formal cross-coupling of phenols with various amines and anilines has now been developed. A variety of substituted phenols were compatible with the standard reaction conditions. Secondary and tertiary aryl amines could thus be synthesized in moderate to excellent yields.

Site-selective arene C-H amination via photoredox catalysis

Over the past several decades, organometallic cross-coupling chemistry has developed into one of the most reliable approaches to assemble complex aromatic compounds from preoxidized starting materials. More recently, transition metal-catalyzed carbon-hydrogen activation has circumvented the need for preoxidized starting materials, but this approach is limited by a lack of practical amination protocols. Here, we present a blueprint for aromatic carbon-hydrogen functionalization via photoredox catalysis and describe the utility of this strategy for arene amination. An organic photoredox-based catalyst system, consisting of an acridinium photooxidant and a nitroxyl radical, promotes site-selective amination of a variety of simple and complex aromatics with heteroaromatic azoles of interest in pharmaceutical research. We also describe the atom-economical use of ammonia to form anilines, without the need for prefunctionalization of the aromatic component.

Copper-Catalyzed Inter- and Intramolecular C-N Bond Formation: Synthesis of Benzimidazole-Fused Heterocycles

A Cu (II)-catalyzed, inter/intramolecular C-N bond formation for the synthesis of various benzimidazole-fused heterocycles in a concise manner has been reported. The robustness of this reaction is demonstrated by the synthesis of a series of benzimidazole-fused heteroaromatics (e.g., pyrido[1,2-a] benzimidazole, benzimidazo[1,2-a]quinolines, benzimidazo [1,2-a]pyrazine, benzo[4,5] imidazo[2,1-b]thiazoles) directly from 2-aminoheteroarenens and 2-iodoarylboronic acids in one-pot. The novel cascade protocol for C-N bond formation operates via unique combination of Chan-Lam type coupling followed by Ullmann-type reaction.

Alkyl Aryl Ether Bond Formation with PhenoFluor

An alkyl aryl ether bond formation reaction between phenols and primary and secondary alcohols with PhenoFluor has been developed. The reaction features a broad substrate scope and tolerates many functional groups, and substrates that are challenging for more conventional ether bond forming processes may be coupled. A preliminary mechanistic study indicates reactivity distinct from conventional ether bond formation.

Microelectrode Arrays and the Use of PEG-Functionalized Diblock Copolymer Coatings

PEG-modified diblock copolymer surfaces have been examined for their compatibility with microelectrode array based analytical methods. The use of PEG-modified polymer surfaces on the arrays was initially problematic because the redox couples used in the experiments were adsorbed by the polymer. This led the current measured by cyclic voltammetry for the redox couple to be unstable and increase with time. However, two key findings allow the experiments to be successful. First, after multiple cyclic voltammograms the current associated with the redox couple does stabilize so that a good baseline current can be established. Second, the rate at which the current stabilizes is consistent every time a particular coated array is used. Hence, multiple analytical experiments can be conducted on an array coated with a PEG-modified diblock copolymer and the data obtained is comparable as long as the data for each experiment is collected at a consistent time point.

Construction of N-containing heterocycles via oxidative intramolecular N–H/X–H coupling

The preparation of N-containing heterocycles using oxidative coupling has become a hot topic recently. This feature article summarized the methodology related to the construction of N-heterocycles through intramolecular oxidative N–H/X–H coupling.

Palladium-catalyzed benzothieno[2,3-b]indole formation via dehydrative–dehydrogenative double C–H sulfuration using sulfur powder, indoles and cyclohexanones

An efficient procedure for benzothieno[2,3-b]indole formation via double C–H sulfuration using sulfur powder is described.

Cu-catalyzed arylation of the amino group in the indazole ring: regioselective synthesis of pyrazolo-carbazoles

Arylated aminoindazoles were synthesized by copper-catalyzed C–N bond cross-coupling with boronic acids. These were then transformed to pyrazolo-carbazoles by Pd-catalyzed regioselective cross-dehydrogenative coupling.

Tuning the optical and electrochemical properties of core-substituted naphthalenediimides with styryl imide substituent

Unusually broad thin-film visible absorption (500–800 nm) for naphthalenediimide molecules was obtained by using the combination of alkylamino core substituents and styryl imide substituents.