Synthesis of 10-Methylacridin-9(10H)-ones through Cu-Catalyzed Intramolecular Oxidative C(sp2)-H Amination of 2-(Methylamino)benzophenones

K2CO3-Catalyzed Dual C-C-Coupled Cyclization to 3-Amino-4-benzoylbiphenyls and In Situ I2-Catalyzed C-N Bond Forming Annulation: A Metal-Free Synthesis of Arylacridones

Unprecedented metal-free cyclization catalysis reactions are developed in a highly regioselective fashion to synthesize 3-amino-4-benzoyl biphenyls and arylacridones with high atom economy. Catalytic K2CO3 is utilized as the only reagent for the unusual rapid dual C-C-coupled cyclization between β-keto enamines and cinnamaldehydes to furnish the functionalized biphenyls. Its C(sp2)-H functionalized C-N bond-forming cyclization was performed in situ using molecular I2 as a catalyst to furnish valuable arylacridones. Plausible mechanisms for the new cyclization reactions are predicted by conducting various control experiments and ESI-MS analyses.

Base-Controlled Synthesis of Fluorescent Acridone Derivatives via Formal (4 + 2) Cycloaddition

A transition-metal-free formal (4 + 2) cycloaddition for the direct assembly of acridone derivatives has been developed from simple and easily accessible o-aminobenzamides and 2-(trimethylsilyl)aryl triflates. The base played an important role in the selective controlled synthesis of N-H and N-aryl acridones. A preliminary study on the fluorescence properties of N-aryl acridones demonstrated that they could be used as fluorescent materials with a broad emission range.

Copper-catalyzed cascade C–N coupling/C–H amination: one pot synthesis of imidazo[1,2-b]indazole

A one-pot, two-fold C–N bond formation protocol has been developed for the construction of imidazo[1,2-b]indazole derivatives.

3d Transition Metals for C-H Activation

C-H activation has surfaced as an increasingly powerful tool for molecular sciences, with notable applications to material sciences, crop protection, drug discovery, and pharmaceutical industries, among others. Despite major advances, the vast majority of these C-H functionalizations required precious 4d or 5d transition metal catalysts. Given the cost-effective and sustainable nature of earth-abundant first row transition metals, the development of less toxic, inexpensive 3d metal catalysts for C-H activation has gained considerable recent momentum as a significantly more environmentally-benign and economically-attractive alternative. Herein, we provide a comprehensive overview on first row transition metal catalysts for C-H activation until summer 2018.

Denitrogenative Suzuki and carbonylative Suzuki coupling reactions of benzotriazoles with boronic acids

Unprecedented palladium-catalyzed denitrogenative Suzuki and carbonylative Suzuki coupling reactions of benzotriazoles with boronic acids have been realized, which afforded structurally diverse ortho-amino-substituted biaryl and biaryl ketone derivatives. The key to this success is due to the development of a rationally designed strategy to achieve the ring opening of benzotriazoles with a synergistic activating-stabilizing effect, which enables the in situ generation of the corresponding ortho-amino-arenediazonium species. The present work opens up a new avenue to utilize benzotriazoles as synthetic equivalents of ortho-amino-arenediazoniums, which otherwise could not be directly accessed by existing synthetic methods.

Recent advances in copper-mediated chelation-assisted functionalization of unactivated C–H bonds

Recent advances in copper-mediated (both stoichiometric and catalytic) chelation-assisted functionalization of unactivated C–H bonds are reviewed.

Synthesis of oxindoles via reductive CO2 fixation

The synthesis of 3-aryl-3-hydroxy-2-oxindoles, which are a structural motif found in various natural products and pharmaceutically active compounds, was conducted via reductive coupling of (2-aminophenyl)(aryl)methanone derivatives and CO₂ as a key step. The conditions employing Mg with chlorotrimethylsilane in DMA are the best for the reductive coupling. The reductive coupling and acid-catalyzed lactam formation can be performed in a one-pot reaction to give the oxindoles.

Recent Trends in Copper-Catalyzed C-H Amination Routes to Biologically Important Nitrogen Scaffolds

Nitrogen-containing heterocycles have found remarkable applications in natural product research, material sciences, and pharmaceuticals. Although the synthesis of this interesting class of compounds attracted the interest of generations of organic chemists, simple and straightforward assembly methods based on transition-metal catalysis have regularly been elusive. The recent advancements in the development of C-H functionalization have helped in accomplishing the synthesis of a variety of complex heterocycles from simple precursors. This Focus Review summarizes the recent advances in one particular field: the copper-catalyzed C-N bond formation reactions via C-H bond functionalization to furnish a comprehensive range of nitrogen heterocycles. Applicability and synthetic feasibility of a particular reaction represent major requirements for the inclusion in this review.

Dual Role of Acetanilides: Traceless Removal of a Directing Group through Deacetylation/Diazotation and Palladium-Catalyzed C-C-Coupling Reactions

The acetamide group enables regioselective oxidative ortho-C-H activation reactions, such as Pd-catalyzed acylation. The synthetic utility of these transformations can be significantly enhanced by using the acetamide as a quasi-leaving group in a subsequent conventional Pd-catalyzed coupling or cross-coupling reaction. The concept is illustrated herein for the synthesis of o-alkenyl- and o-arylphenones, which have potential for the synthesis of arylated aromatic heterocycles.

A POCl3-mediated synthesis of substituted fused azoacridones derivatives

We provide an efficient approach to synthesize fused azoacridone derivatives, which showed broad substrate scope and good yields.

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.

PhI(OAc)2-mediated intramolecular oxidative aryl-aldehyde Csp(2)-Csp(2) bond formation: metal-free synthesis of acridone derivatives

A metal-free protocol for direct aryl-aldehyde Csp(2)-Csp(2) bond formation via a PhI(OAc)2-mediated intramolecular cross-dehydrogenative coupling (CDC) of various 2-(N-arylamino)aldehydes was developed. The novel methodology requires no need of preactivation of the aldehyde group, is applicable to a large variety of functionalized substrates, and most of all provides a convenient approach to the construction of biologically important acridone derivatives.

Syntheses of indolizinones from an intramolecular one-pot process of gem-dibromoolefins

A rare type of indolizinone is constructed from an Intramolecular one-pot process from gem-dibromoolefins.