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An intramolecular C-H arylation reaction was established for the construction of a series of 6H-benzocchromene and dihydrophenanthridine derivatives under visible light irradiation. The products were characterized by H NMR and C NMR spectra. Compared with traditional methods, this method uses clean and renewable light energy to drive reactions, avoiding strict reaction conditions such as high temperature and high pressure. In addition, this method has the advantages of easily available starting materials, broad substrate scopes, mild reaction conditions and simple operation [ABSTRACT FROM AUTHOR]

Unusual direction of the C–H arylation of 2-(het)aryl[1,2,4]triazolo[1,5-a]pyrimidines with (het)aryl halides under catalysis by ruthenium(II) complexes has been revealed. The reaction involved activation of the C7–H bond rather than the Cα–H bond of the (het)aryl substituent at C2 of the triazolopyrimidine core. The arylation of 2-substituted [1,2,4]triazolo[1,5-a]pyrimidines with (het)aryl bromides afforded a series of 7-(het)aryl derivatives in good yields. [ABSTRACT FROM AUTHOR]

The visible light-assisted photocatalysis approach allows more sustainable and atom-economical C–H bond arylation processes. The polymer-based photocatalysts are an attractive choice because of their variable design and development feasibility as well as effective catalytic applications. In the present work, by following the basic principles of green chemistry, we have chosen an environmentally friendly and biologically suitable chemical i.e. Erythrosine B as a unit molecule for the generation of photocatalyst EP (C20H8O5S4). The generation of EP has been performed via a one-pot solvothermal reaction of Erythrosine B with sulfur powder. The structural analysis of the EP evidence the generation of an interesting example 2D-polymeric assembly where disulfide (–S–S–) units are acting as linkers and show high thermal stability up to 800 °C (39.9% left as a residue). The low optical band gap of 2.08 eV and electrochemical band gap of 2.09 eV favors its catalytic applicability. The catalytic investigation reveals excellent applicability of EP in C–H arylation (yield 98.5% & selectivity 99%). [ABSTRACT FROM AUTHOR]

C–H arylation of heterocyclic compounds is a very interesting and important research field in chemistry for the formation of C–C bonds, but unfortunately, few methods have been reported for this purpose. In this attractive and highly efficient methodology, we wish to report that copper (I) chloride immobilized on magnetic nanoparticles modified with benzothiazole-pyrimidine Ligand (Fe3O4@BTH-Pyr-CuCl) is a novel and efficient magnetically recoverable catalyst for carbon–carbon bond formation through C–H arylation of a category of heterocyclic compounds by aryl iodides in the presence of KOAc in PEG under mild conditions. Under this catalytic system, A category of heterocyclic substrates including benzo[d]oxazole, benzo[d]thiazole, 1-methyl-1H-benzo[d]imidazole, 2,5-diphenyloxazole, benzofuran, 2-phenyl-1,3,4-oxadiazole and 2-phenylimidazo[1,2-a]pyridine were used as substrate and the desired products were prepared with high to excellent yields. Reusability tests revealed that the Fe3O4@BTH-Pyr-CuCl catalyst can be reused at least 7 runs without significant decrease in its catalytic efficiency. ICP-OES, VSM and SEM techniques confirmed the recovered Fe3O4@BTH-Pyr-CuCl catalyst was very stable and had high magnetic property despite the utilization for 7 runs. [ABSTRACT FROM AUTHOR]

An efficient method for the synthesis of 1-substituted 5-aryl-1,2,4-triazoles by selective C—H arylation of 1-substituted 1,2,4-triazoles with non-activated aryl chlorides and aryl bromides under the catalysis by a palladium complex with a N-heterocyclic carbene ligand IPr*OMe using 1,1,2,2-tetraphenylethane-1,2-diol (TPEDO) as a catalyst activator is reported. [ABSTRACT FROM AUTHOR]

We demonstrated a straightforward photo-induced strategy for decarbonylative aryl C H arylation with the aldehydes. This transformation proceeds with operational simplicity and solvent-free conditions, does not need for 1,2-dinitrobenzene additive, and tolerates unsuccessful functionalities (e.g., 4-pyridine, NO 2 and SO 2 Me) in previously reported protocols. [Display omitted] • Developing a new photothermal-catalytic approach for divergent construction of biaryl skeletons avoiding the use of equivalent o -dinitrobenzene. • High functional-group tolerance such as previously unsuccessful 4-pyridine, -NO 2 and -SO 2 Me. • Offering a new strategy for aliphatic aldehydes for the first time. • The reaction proceeds through decarbonylation of aldehyde via photothermal excitation to generate an aromatic anion. Here, by using eosin Y as a preferable catalyst, we present a photothermally induced decarbonylative aryl C H arylation with the aldehydes. This transformation proceeds with operational simplicity and solvent-free conditions, does not need for 1,2-dinitrobenzene additive, and tolerates unsuccessful functionalities (e.g., 4-pyridine, NO 2 and SO 2 Me) in previously reported protocols. In addition to the aryl aldehydes, the alkyl ones are also compatible with this transformation. Mechanistic investigations reveal that the reaction undergoes aldehyde decarbonylation to afford aryl radicals in situ , its regioselective addition to the arenes followed by single electron oxidation and homolytic hydrogen abstraction gives rise to the desired cross-coupling products. Give the striking features, this work offers a useful platform to directly access various biaryls. [ABSTRACT FROM AUTHOR]

In pristine graphitic carbon nitride (g-CN), amino groups often function as structural defects that trap photogenerated charges, resulting in low photocatalytic activity as well as reaction with nitrite, aldehyde, etc., ensuing in poor product yield. Without significantly altering the optical characteristics, the removal of amino groups is necessary to increase the photocatalytic activity and structural stability of pristine g-CN. The deamino graphitic carbon nitride (DA-gCN-5) was prepared by tert-butyl nitrite (TBN)- treatment, characterized and used as a photocatalyst for the radical C-H arylation of heteroarenes using anilines as radical source. Indeed, the photophysical characteristics of DA-gCN-5 and those of pristine g-CN are very comparable, except that DA-gCN-5 has a fewer residual amino groups, higher crystallinity, and compressed structure with a different morphology. Moreover, DA-gCN-5-catalyzed C-H arylation reaction offers greater product yield in a shorter reaction time compared to that of pristine g-CN in the coupling between heteroarenes and the in situ generated aryl diazonium salts from anilines under visible light irradiation. The amino groups in pristine g-CN absorbed the TBN that was added to convert aniline into the appropriate diazonium ions during the reaction. As a result, deamino graphitic carbon nitride produced by chemical treatment has better photophysical properties and catalytic activity than pristine g-CN. Additionally, this is the first method that uses diazotization reaction for the preparation of deamino graphitic carbon nitride, as far as we are aware. [ABSTRACT FROM AUTHOR]

Keywords: dibenzo[ f, h ]quinolones; polycyclic aromatic hydrocarbons; C-H arylation; reductive cyclodehydrogenation; ruthenium EN dibenzo[ f, h ]quinolones polycyclic aromatic hydrocarbons C-H arylation reductive cyclodehydrogenation ruthenium 2779 2785 7 08/17/23 20230901 NES 230901 Graph Polycyclic aromatic hydrocarbons (PAHs) typically contain two or more fused benzene rings and are structurally characterized by a high degree of rigidity and -conjugation. We present in this work a new approach to synthesize dibenzo[ I f i , I h i ]quinolines via a two-step procedure involving the ruthenium-catalyzed C-H arylation followed by the potassium-mediated reductive cyclodehydrogenation (Figure 1e). For the substituents, only the relatively electron-rich groups such as OMe, Me, and Ph were used, because electron-deficient substituents, e.g., Cl and CO SB 2 sb Et, are not tolerated in the subsequent reductive cyclodehydrogenation reaction with potassium. Zhang and co-workers developed a palladium-catalyzed double cross-coupling reaction between cyclic diaryliodonium salts and 2-chloropyridinyl acids to access dibenzo-[ I f i , I h i ]quinolines and their derivatives (Figure 1a). [Extracted from the article]

Keywords: benzyne; N -alkylpyridinium salts; dicarbofunctionalization; visible light; C-H arylation; de Mayo-type reaction EN benzyne N -alkylpyridinium salts dicarbofunctionalization visible light C-H arylation de Mayo-type reaction 2159 2165 7 07/03/23 20230718 NES 230718 It is widely known that arynes are a useful and transient intermediate in synthetic organic chemistry. After cooling to room temperature, the reaction mixture was concentrated in vacuo and the residue was purified by silica gel flash column chromatography (hexane/EtOAc = 2:1) to afford B 3q b as a yellow solid; mp 157-160 °C. After cooling to room temperature, the reaction mixture was concentrated in vacuo and the residue was purified by silica gel flash column chromatography (hexane/EtOAc = 5:1) to afford B 3r b as a yellow solid; mp 133-135 °C. After cooling to room temperature, the reaction mixture was concentrated in vacuo and the residue was purified by silica gel flash column chromatography (hexane/EtOAc = 2:1) to afford B 3p b as sa yellow solid; mp 130-132 °C. [Extracted from the article]

Imidazole-4-carboxamide (ICA), which is one of the groups of "fairy chemicals" (FCs) that cause the fairy ring phenomena, has plant growth inhibitory activity. FCs have the potential as candidates for a new family of plant hormones as they have been found endogenously in all plant species tested and show growth-regulating activities against the plants. While basic research on FCs is progressing, they are also expected to be applied not only to agrochemicals but also as pharmaceuticals. Derivatization of one of the FCs, 2-azahypoxanthine, and the structure–activity relationship (SAR) studies have clarified its activity as a plant growth promoter. Yet, ICA has not been derivatized at all and SAR regarding its activity remains unknown. In this study, we synthesized the derivatives of ICA by direct C–H arylation of ICA precursors and evaluated its activity in rice. The 12 total compounds including the arylated ICAs and their precursors were evaluated for root and shoot elongation in rice, resulting in the discovery that a number of compounds unexpectedly have an elongation activity in the root and shoot. [ABSTRACT FROM AUTHOR]

Anilines selectively arylated at their ortho , meta or para positions are useful building blocks in synthesis and have found applications in many areas. The most straightforward method for their synthesis relies on the direct arylation of a C(sp2)–H bond of anilines, an attractive strategy avoiding the prefunctionalization of the starting anilines provided that such arylations proceed with high levels of regioselectivity. Such reactions are presented and discussed, in a comprehensive manner, in this review article, with an emphasis on the regioselectivity of the processes and factors governing both the reactivity and selectivity. 1 Introduction 2 ortho -Arylation of Anilines 2.1 Direct C(sp2)–H ortho -Arylation of Anilines 2.2 Directed C(sp2)–H ortho -Arylation of Anilines 3 meta -Arylation of Anilines 4 para -Arylation of Anilines 4.1 Direct C(sp2)–H para -Arylation of Anilines via Oxidative Radical Homodimerization 4.2 Direct C(sp2)–H para -Arylation of Anilines via Transition-Metal Catalysis 5 Conclusion and Outlook [ABSTRACT FROM AUTHOR]

[Display omitted] A simple and efficient electrochemical C–H arylation of five- membered active heteroarenes involves the application of arenediazonium salts generated in situ from anilines and tert - butyl nitrite. A cathodic reduction-induced radical chain mechanism is proposed. [ABSTRACT FROM AUTHOR]

A new solvent/ligand-controlled switchable C–H arylation of 1-methyl-4-nitro-1 H -indazole catalyzed by Pd(OAc)2 was achieved. A bidentate ligand in DMA promoted the activation at C7 position, while a phosphine ligand in H2 O oriented the arylation at C3 position. The C3 and C7 arylation products were obtained in moderate to good yields and with high regioselectivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Meso-aryl substituted corrole based photocatalysts are reported. • Corrole were used to catalyse C–H arylation and borylation reactions. • The method utilized 0.5 to 1 mol% of corrole catalyst under blue light. • Corrole catalysts also worked efficiently under sunlight, with yields up to 80%. • DFT studies indicated SET from the singlet state of catalyst to the substrate. The visible light mediated metal-free approach has been developed for C–H arylation and borylation employing anilines as starting material. A series of meso -aryl corroles (A 3 and A 2 B type) were synthesized and their catalytic potential was tested in blue light and sunlight. The method includes substituted anilines as source of expensive aryl diazonium salts and utilizes only 0.5 to 1 mol% of corrole catalyst at room temperature. Corrole catalyst worked efficiently under the blue light/sunlight to produce heterobiaryls and aryl boronic esters in decent to good yields (15–80 %). Mechanistic insight was obtained from TD-DFT studies, which suggested single electron transfer (SET) from the singlet state of corrole catalyst to the aryl diazonium salt. The paper demonstrates corrole based photo-redox catalysis as a mild, green and eco-sustainable alternative for the C–H arylation reactions. [ABSTRACT FROM AUTHOR]

In this contribution, an eco-friendly, sustainable, and efficient palladium nanoparticle-decorated chitosan (Pd@Chitosan) catalyst was synthesized by a simple impregnation method. The synthesized material was utilized as a heterogeneous catalyst for the C-H arylation of benzothiazole under ultrasonic irradiation. The Pd@Chitosan catalyst efficiently catalyzed the conversion of aryl iodides and bromides to 1-(4-(benzothiazol-2-yl)phenyl)ethan-1-one selectively. A single product of 83–93% yield was obtained in N,N-dimethylformamide solvent at 80 °C for 2.5h. This study reveals that Pd@Chitosan is an efficient catalyst, which catalyzes the C-H arylation with good reaction yields. The activity of the Pd@Chitosan is due to the presence of highly dispersed Pd(0) nanoparticles on the surface of the chitosan and Pd2+; a tentative mechanism was proposed based on the XPS results of the fresh catalyst and spent catalyst. [ABSTRACT FROM AUTHOR]

The development of a mild, general, and green method for the C-H arylation of pyrazoles with relatively unreactive aryl halides is an ongoing challenge in organic synthesis. We describe herein a novel sonophotoreactor based on an ultrasonic cleaning bath and blue LED light (visible light) that induce copper-catalyzed monoarylation for pharmacologically relevant pyrazoles. The hybrid effect of ultrasonic irradiation and blue LED is discussed to interpret the observed synergistic action. A broad array of pyrazoles coupled with iodobenzene avoids expensive palladium metal or salts, and certain designed substrates were attained. Only comparatively inexpensive copper(I)iodide and 1,10-phenanthroline were used all together as the catalyst. The presented technique is a greener way to create C-H arylation of pyrazoles. It significantly reduces the amount of energy needed. [ABSTRACT FROM AUTHOR]

Bonds between hydrogen and carbon atoms are the most frequent type of bonds in organic molecules. The ability to replace hydrogen atoms by making other types of bonds to carbon atoms can enable simpler access to complex organic molecules by substituting multistep synthetic sequences. The use of transition metal catalysts to activate C–H bonds is particularly attractive as it offers control over the reactivity and selectivity through catalyst design. However, such functionalization includes the difficult breaking of strong C–H bonds that are not activated by the presence of other groups. Additionally, the common presence of a number of C–H bonds in a molecule raises the issue of site-selectivity because differentiation of C–H bonds that are in sterically and electronically similar environments is a challenge. We discuss selected recent developments that are a part of the long-term research interest in mild and selective C–H activation reactions with a focus on the replacement of C–H bonds with C–aryl groups and an emphasis on the work of our group.

Two novel hyper-cross-linked fluorinated microporous polyketone networks (FMPN-1 and FMPN-2) with permanent porosity and narrow pore size distribution were synthesized via a facile "one-step" polycondensation between the trifluoroacetophenone-based monomers and 1,3,5-triphenylbenzene. The result polymers were investigated by FTIR, solid state NMR, EDX, XRD, TGA, SEM, and TEM et al. The geometry configurations difference of building blocks resulted in the polyketone networks exhibiting the BET special surface areas from 622 to 706 m2 g−1 and total volume from 0.58 to 0.66 cm3 g−1. What's more, ideal adsorbed solution theory (IAST) analysis showed that the two polymers possessed good C 3 H 8 /CH 4 , C 2 H 6 /CH 4 selectivities at 298K/1 bar. Together with the excellent thermal and physicochemical stabilities, the microporous fluorinated polyketone networks obtained in this work showed promising applications in adsorption/separation for C 1 –C 3 hydrocarbons. [Display omitted] • Fluorinated microporous polyketone networks through direct C–H arylation polycondensation were prepared. • The result polymers possessed high thermal stability with the 3.0 % weight loss exceeded 488 °C. • The selectivities of C 3 H 8 /CH 4 and C 2 H 6 /CH 4 reached 317.2 and 21.6, respectively. [ABSTRACT FROM AUTHOR]

C–H activation of functionally rich molecules without the need for directing groups promises shorter organic syntheses and late-stage diversification of molecules for drug discovery. We highlight recent examples of palladium-catalyzed nondirected functionalization of C–H bonds in arenes as limiting substrates with a focus on the development of the concept of spatial anion control for direct C–H arylation. 1 C–H Activation and the CMD Mechanism 2 Nondirected C–H Functionalizations of Arenes as Limiting Substrates 3 Nondirected C–H Arylation 4 Spatial Anion Control for Direct C–H Arylation 5 Coordination Chemistry with Spatial Anion Control 6 Conclusion [ABSTRACT FROM AUTHOR]

Atropisomeric molecules are privileged scaffolds, not only as ligands for asymmetric synthesis, but also as biologically active products and advanced materials. Although very attractive from a sustainability viewpoint, the direct construction of the stereogenic axis through asymmetric C–H arylation is very challenging and consequently only a few examples have been reported. This short review summarizes these very recent results on the atropo-enantio or diastereo­selective synthesis of atropisomeric (hetero)biaryl molecules; transformations during which the Ar–Ar atropisomeric axis is formed during the C–H activation process. 1 Introduction 2 Atropo-enantioselective Intermolecular Pd-Catalyzed C–H Arylation of Thiophene Derivatives 3 Atropodiastereoselective Intermolecular Pd-Catalyzed C–H Arylation towards Terphenyl Scaffolds Bearing Two Atropisomeric Axes 4 Atropo-enantioselective Intramolecular Pd-Catalyzed C–H Arylation towards Atropisomeric Benzodiazepinones 5 Atropo-enantioselective Intermolecular Pd-Catalyzed C–H Arylation of Heteroarenes 6 Rh-Catalyzed Atropo-enantioselective C–H Arylation of Diazonaphthoquinones 7 Conclusion

The regioselective C–H arylation of substituted polycyclic aromatic hydrocarbons (PAHs) is a desired but challenging task. A copper-catalyzed C7–H arylation of 1-naphthamides has been developed by using aryliodonium salts as arylating reagents. This protocol does not need to use precious metal catalysts and tolerates wide variety of functional groups. Under standard conditions, the remote C–H arylation of other PAHs including phenanthrene-9-carboxamide, pyrene-1-carboxamide and fluoranthene-3-carboxamide has also accomplished, which provides an opportunity for the development of diverse organic optoelectronic materials.

An efficient synthesis of tetrabenzo[a,d,j,m]coronene derivatives having alkyl and alkoxy substituents at the 3, 6, 13, and 16-positions was achieved based on the ruthenium-catalyzed coupling reactions of anthraquinone derivatives with arylboronates via C–H and C–O bond cleavage. The reaction sequence involving the arylation, carbonyl methylenation, and oxidative cyclization effectively provided various tetrabenzo[a,d,j,m]coronenes in short steps from readily available starting materials. Tetrabenzo[a,d,j,m]coronenes possessing two different types of substituents were obtained selectively by sequential chemoselective C–O arylation and C–H arylation. The 1H NMR spectra of the tetrabenzo[a,d,j,m]coronene product indicated its self-assembling behavior in CDCl3.

Privileged biaryl frameworks, BINOL and NOBIN, were efficiently constructed with sole 1-DNQs as arylation reagents under one set of reaction conditions. The judicious selection of palladium-catalytic system plays a pivotal role in the excellent selectivities. This transformation accommodated fairly broad substrate generality for both 2-naphthol and N-Boc-2-naphthylamine and afforded the structurally diversified BINOLs and NOBIN derivatives in high efficiency. Notably, the bromo-substituents which cannot survive in conventional palladium-catalyzed reactions were well-compatible with this set of conditions, providing an effective handle for further enriching the library of BINOLs and NOBINs. Preliminary attempts on the asymmetric variant of this reaction were also performed with up to 80:20 er for BINOLs synthesis. [ABSTRACT FROM AUTHOR]

Synthetic methodologies involving the formation of carbon–carbon bonds from carbon–hydrogen bonds are of significant synthetic interest, both for efficiency in terms of atom economy and for their undeniable usefulness in late-stage functionalization approaches. Combining these aspects with being metal-free, the radical C–H intermolecular arylation procedures covered by this review represent both powerful and green methods for the synthesis of (hetero)biaryl systems. 1 Introduction 2 Arylation with Arenediazonium Salts and Related Derivatives 2.1 Ascorbic Acid as the Reductant 2.2 Hydrazines as Reductants 2.3 Gallic Acid as the Reductant 2.4. Polyanilines as Reductants 2.5 Chlorpromazine Hydrochloride as the Reductant 2.6 Phenalenyl-Based Radicals as Reductants 2.7 Electrolytic Reduction of Diazonium Salts 2.8 Visible-Light-Mediated Arylation 3 Arylation with Arylhydrazines: Generation of Aryl Radicals Using an Oxidant 4 Arylation with Diaryliodonium Salts 5 Arylation with Aryl Halides 6 Conclusions [ABSTRACT FROM AUTHOR]

In this contribution, an eco-friendly, sustainable, and efficient palladium nanoparticle-decorated chitosan (Pd@Chitosan) catalyst was synthesized by a simple impregnation method. The synthesized material was utilized as a heterogeneous catalyst for the C-H arylation of benzothiazole under ultrasonic irradiation. The Pd@Chitosan catalyst efficiently catalyzed the conversion of aryl iodides and bromides to 1-(4-(benzothiazol-2-yl)phenyl)ethan-1-one selectively. A single product of 83–93% yield was obtained in N,N-dimethylformamide solvent at 80 °C for 2.5h. This study reveals that Pd@Chitosan is an efficient catalyst, which catalyzes the C-H arylation with good reaction yields. The activity of the Pd@Chitosan is due to the presence of highly dispersed Pd(0) nanoparticles on the surface of the chitosan and Pd2+; a tentative mechanism was proposed based on the XPS results of the fresh catalyst and spent catalyst.

The development of a mild, general, and green method for the C-H arylation of pyrazoles with relatively unreactive aryl halides is an ongoing challenge in organic synthesis. We describe herein a novel sonophotoreactor based on an ultrasonic cleaning bath and blue LED light (visible light) that induce copper-catalyzed monoarylation for pharmacologically relevant pyrazoles. The hybrid effect of ultrasonic irradiation and blue LED is discussed to interpret the observed synergistic action. A broad array of pyrazoles coupled with iodobenzene avoids expensive palladium metal or salts, and certain designed substrates were attained. Only comparatively inexpensive copper(I)iodide and 1,10-phenanthroline were used all together as the catalyst. The presented technique is a greener way to create C-H arylation of pyrazoles. It significantly reduces the amount of energy needed.

We recently reported a general and practical strategy for the Bi(V)-mediated C–H arylation of phenols and naphthols. Our telescoped protocol proceeds via transmetallation from readily available arylboronic acids to a stable Bi(III) precursor, oxidation to a reactive Bi(V) intermediate, and subsequent ortho -selective phenol arylation. The process exhibits broad scope with respect to both components and tolerates functionality that is incompatible with conventional cross-coupling methods. Preliminary investigations provide insight into the mechanism of each key reaction step. 1 Introduction 2 Design of a Modular and Practical Arylating System 3 B-to-Bi Transmetallation: Scope and Mechanism 4 Oxidative C–H Arylation: Exemplification and Mechanism 5 Conclusionsions [ABSTRACT FROM AUTHOR]

Peripherally arylated tetrathiafulvalenes with an anthraquinoid spacer (TTFAQs) have been synthesized by using palladium-catalyzed direct C–H arylation of the 1,3-dithiole rings. Electrochemical analysis by cyclic voltammetry has revealed that the new tetraarylated TTFAQs show one pair of simultaneous two-electron transfer waves as the parent TTFAQ does. The hydrolysis of the tetra(p -ethoxycarbonylphenyl)-substituted derivative affords the corresponding tetracarboxylic acid, which forms a new double-helical metal-organic framework upon complexation with cobalt(III) nitrate. [ABSTRACT FROM AUTHOR]

Sulfur-containing functional π-conjugated cores play key roles in materials science, mostly due to their unique electrochemical and photophysical properties. Among these, the excellent electron donor tetrathiafulvalene (TTF) has occupied a central position since the emergence of organic electronics. Peripheral C–H modification of this highly useful sulfur-containing motif has resulted in the efficient creation of new molecules that expand the applications of TTFs. This Short Review begins with the development of the palladium-catalyzed direct C–H arylation of TTF. Subsequently, it summarizes the applications of this efficient C–H transformation for the straightforward synthesis of useful TTF derivatives that are employed in a variety of research fields, demonstrating that the development of a new reaction can have a significant impact on chemical science. 1 Introduction 2 Development of the Palladium-Catalyzed Direct C–H Arylation of TTF 3 Synthesis of TTF-Based Tetrabenzoic Acid and Tetrapyridine for MOFs 4 Synthesis of TTF-Based Tetrabenzaldehyde and Tetraaniline for COFs 5 Tetraarylation of TTFAQ 6 Synthesis of Multistage-Redox TTF Derivatives 7 Miscellaneous Examples 8 Conclusions [ABSTRACT FROM AUTHOR]

Summary of main observation and conclusion: A general method for visible light‐induced copper‐catalyzed arylation of sp2 C—H bonds of azoles has been developed. The method employs aryl halide as the coupling partner, lithium alkoxide as base. A variety of azoles including benzooxazole and benzothiazole can be arylated. Furthermore, electron‐poor heterocycles such as thiophene possessing one electron‐withdrawing group can also be arylated. [ABSTRACT FROM AUTHOR]

Summary of main observation and conclusion: A general method for visible light‐induced copper‐catalyzed arylation of sp2 C—H bonds of azoles has been developed. The method employs aryl halide as the coupling partner, lithium alkoxide as base. A variety of azoles including benzooxazole and benzothiazole can be arylated. Furthermore, electron‐poor heterocycles such as thiophene possessing one electron‐withdrawing group can also be arylated. [ABSTRACT FROM AUTHOR]

Microwaves (MW) are often the most efficient, in terms of heat exchange and conversion rate, of all the energy sources used to promote chemical reactions thanks to fast volumetric dielectric heating, and metal-catalyzed synthetic reactions under heterogeneous conditions are an eloquent example. We herein report a MW-assisted green protocol for the C-H arylation of thiophenes with substituted aryl halides. This sustainable protocol carried out in γ-valerolactone (GVL) is catalyzed by Pd nanoparticles embedded in cross-linked β-cyclodextrin. In view of the excellent results achieved with activated substrates, the one-pot synthesis of a 4(3H)-quinazolinone derivative has been accomplished. A pressure-resistant MW reactor, equipped with multiple gas inlets, was used for sequential (i) C-H arylation, (ii) reduction, and (iii) carbonylation in the presence of the same catalyst, but under different gas atmospheres. The robust heterogeneous Pd catalyst showed limited metal leaching in GVL, making this an efficient MW-assisted process with high atom economy.

Over the past ten years, a combination of organic additive and t -BuOK/ t -BuONa has been successfully used for the direct C–H arylation of arenes. Conceptually different from transition-metal-catalyzed cross-coupling reactions, these t -BuOK-mediated reactions have raised significant curiosity among organic chemists. Herein, a systematic computational study of each elementary step of the t -BuOM (M = K, Na, Li)/ N 1 , N 2-dimethylethane-1,2-diamine (DMEDA) mediated direct C–H arylation of benzene is detailed. The presented mechanistic proposal relies on the complexation and reaction of t -BuOM with DMEDA (additive), which leads to the formation of different complexes such as SED(M+)... PhI. These complexes mainly involve coordination of the metal ion (from t -BuOM) to the additive and iodobenzene via stabilizing cation–lone pair and cation–π interactions. Such complexation of a metal ion to an additive and iodobenzene not only ensures facile electron transfer to iodobenzene but also provides a lowest energy pathway for the subsequent radical addition and deprotonation step. [ABSTRACT FROM AUTHOR]

UiO‐66 is a classic Metal–organic framework (MOF) that constructed by zirconium cations and terephthalate with high chemical and thermal stability. Using pristine UiO‐66 nanocrystals as the catalysts, the carbon–carbon bond formation based on denitrogenative substitution of aryl diazonium salts has been achieved under mild condition. The C–H arylation of both enol acetates and heteroarenes could be performed in aqueous medium without other metal assistance. The UiO‐66 catalyst shows good water stability and reusability as well as impressive functional group tolerance. [ABSTRACT FROM AUTHOR]

Biaryl scaffolds are prevalent in natural products and drug molecules, and biaryl-containing compounds have been shown to exhibit diverse and interesting biological activities. To date, numerous synthetic methods, particularly direct C–H bond activation, have been developed for the construction of such scaffolds, due to their interesting structural features and biological profiles. We highlight herein recent advances in the construction of biologically important biaryl fragments through direct C–H bond activation and also demonstrate the application of direct C–H arylation in the total synthesis of biaryl-containing natural products and drug molecules. Selected biaryl-containing compounds [ABSTRACT FROM AUTHOR]

The availability and application of direct, functional group-compatible C–H activation methods for late-stage modification of small-molecule bioactives and other valuable materials remains an ongoing challenge in organic synthesis. In the current study, we demonstrate that a LED-activated, photoredox-mediated, Pd(OAc)2-catalyzed C–H arylation, employing a phenyldiazonium aryl source and either tris(2,2′-bipyridine)ruthenium(II) or (2,2′-bipyridine)bis[3,5-di-fluoro-2-[5-(trifluoromethyl)-2-pyridinyl-kN][phenyl-kC]iridium(III) as photoredox initiator, may successfully produce unprecedented mono- and bis-phenyl derivatives of functionality-rich 2,6-diphenylpyrimidine substrates at room temperature. The series of 19 substrates employed herein, which share the biologically-relevant 4-methyl-2,6-diphenylpyrimidine-5-carboxylate scaffold, were generated via a synthetic route involving (3-component) Biginelli condensation, oxidative dehydrogenation of the obtained 3,4-dihydropyrimidin-2(1H)-one to 2-hydroxypyrimidine, O-sulfonylation, and Suzuki-Miyaura C–C cross-coupling. Submission of these substrates to pyrimidine-N-atom-directed C–H arylation conditions led to regioselective phenylation at the ortho site(s) of the pyrimidine-C2-connected phenyl ring, revealing substituent-dependent electronic and steric effects. A focused library of 18 mono- and 10 bis-phenyl derivatives was generated. Its members exhibit interesting 3D and peripheral substitution features that render them promising for evaluation in drug discovery efforts.

Transition-metal-free direct arylation of C-H or N-H bonds is one of the key emerging methodologies that is currently attracting tremendous attention. Diaryliodonium salts serve as a stepping stone on the way to alternative environmentally friendly and straightforward pathways for the construction of C-C and C-heteroatom bonds. In this review, we emphasize the recent synthetic advances of late-stage C(sp2)-N and C(sp2)-C(sp2) bond-forming reactions under metal-free conditions using diaryliodonium salts as arylating reagent and its applications to the synthesis of new arylated bioactive heterocyclic compounds.

A straightforward enantiomerically pure synthesis of the heterocyclic core of the D-series GE2270 is reported. The synthetic strategy combines the Hantzsch thiazole’s building condensation with a cross-coupling reaction including direct C–H hetarylation to build and connect step-by-step thiazolyl moieties to the 5-bromopicolinate as readily available starting material.

Abstract Pd/C was found to be an efficient and convenient metal catalyst for intramolecular C–H arylation reactions in the synthesis of phenanthridinones and dibenzo-α-pyrones. A variety of phenanthridinones and dibenzo-α-pyrones were synthesized under the highly active catalytic system of Pd/C-KOAc-DMA in moderate to excellent yields. The high catalytic activity, high recyclability, low costs, and ease of removal of Pd/C, combined with its commercial availability, render this protocol attractive for both synthetic and industrial applications.

This report describes a highly enantioselective oxidative sp3 C–H arylation of N-aryltetrahydroisoquinolines (THIQs) through a dual catalysis platform. The combination of the photoredox catalyst, [Ir(ppy)2(dtbbpy)]PF6, and chiral copper catalysts provide a mild and highly effective sp3 C–H asymmetric arylation of THIQs.

Herein, we are reporting metal‐free conditions for radical initiation and direct C–H arylation of N‐heteroarenes. Starting from aniline, the corresponding arenediazonium salt generated in situ is reduced to an aryl radical in the presence of chloropromazine hydrochloride, a new reagent for this application. The optimized procedures are mild, operationally simple, and are working successfully with more diverse substrates in comparison to reported methods. The optimized method is also employed for the synthesis of marine natural products Pentabromo‐ and Pentachloropseudilins (PBP/PCP). In the present study, we also validated the potential of the Pentachloropseudilin (PCP), thus synthesized, for inhibition of Myosin1 function in mammalian cells and confirmed that PCP phenocopies Myosin1c depletion in cells. [ABSTRACT FROM AUTHOR]

PAD4 is a promising epigenetic drug target for various cancers and immune diseases. In this work, we applied a Cu-catalyzed C–H arylation reaction of N-heteroarene to the synthesis of complex non-covalent PAD4 inhibitors bearing a bi-heteroaryl pharmacophore. This strategy allowed us to access various analogs of C2-aryl substituted benzimidazoles from a common benzimidazole core and easily accessible aryl iodides. Preliminary SAR studies revealed the indole motif of GSK-484 is critical to its activity. Replacing the N-cyclopropylmethyl group to N-benzyl group on the indole ring of GSK-484 resulted in more than 5-fold increase in cell killing efficacy against 4T1 cell line. [ABSTRACT FROM AUTHOR]

Abstract A one-pot, multicomponent-type, solvent-free Pd(II)-catalyzed direct β -C-H activation/arylation of carboxamides involving anhydrides as substrates via in situ installation of directing group (DG) is reported. Typically, the DG-assisted β -C-H activation/arylation of carboxamides is a two-step process comprising the installation of DG and Pd(II)-catalyzed C H arylation. We attempted a multicomponent-type reaction comprising an anhydride, a DG (e.g. 8-aminoquinoline), an aryl iodide in the presence of the Pd(II) catalyst and an appropriate additive. Different anhydrides, DGs, aryl iodides, catalysts and additives were screened to reveal the scope of this multicomponent-type C H arylation reaction process and various β -C-H arylated carboxamides were obtained in satisfactory to good yields. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

The development of an oriented arylation process dedicated to the naphthalene core is presented. Our approach is based on dual role of N‐tosyl carboxamides acting jointly as a directing group in a first C–H arylation step and as a "CO" or "CO–NH" fragment precursor in a further construction step of naphthalene‐based fluorenone or phenanthridinone derivatives. The presence of the directing group in position 1 and 2 of the naphthalene platform allowed selective arylations in position 2 and 3 respectively. Our study represents a first synthetic and general entry of C–H arylation at naphthalene platforms towards the preparation of extended fluorenones as well as benzo‐fused phenanthridinones. Further, the C–H arylation and cyclisation sequence represents a useful way to the preparation of novel extended tetra‐ and pentacyclic fluorenones bearing both electron donating as well as electron withdrawing groups in various substitution patterns. Additionally, both the regioselectivity and the reaction paths of the cyclization leading to the fluorenone architectures was studied by DFT calculations which fully complement experimental observations. Dedicated to naphthalene derivatives. The Pd‐catalysed C–H arylation of naphthalene platforms is illustrated along with the dual role of the N‐tosyl carboxamides group. The developed approach results in an improved access to linear and angular extended fluorenone and phenanthridinone architectures [ABSTRACT FROM AUTHOR]

Herein we report a study on the reactivity of C2‐quinoline‐substituted furan, thiophene and pyrrole derivatives in palladium‐catalyzed direct C–H arylation. The regioselectivity of the reaction was strongly influenced by site position of the attached five‐membered heterocycle thus giving rise to C3‐ and/or C5‐arylated products. Furthermore, the Hammett correlation performed on 5‐substituted‐8‐(furan‐2‐yl)quinolines indicates that a marginally positive charge is building up in the rate determining transition state and thus pointing towards the electrophilic metalation‐deprotonation reaction mechanism. The regioselectivity of the arylation reaction of five‐membered heterocycles bearing a quinoline directing group was studied. The transformation was strongly influenced by site position of the attached five‐membered heterocycle thus giving rise to C3‐ and/or C5‐arylated products. [ABSTRACT FROM AUTHOR]

A facile and environmentally benign Pd-catalyzed direct C-H arylation polymerization (DAP) has been developed for the syntheses of homo- and copolymers of anionic-group-functionalized 3,4-ethylenedioxythiophenes with high yields (up to 99%), high molecular weights, and narrow polydispersities. The effects of various Pd catalysts, phosphine ligands, and additives on the properties of the polymers have been examined. The method gives anionic poly(3,4-ethylenedioxythiophenes) with higher molecular weights than those produced by the previously reported chemical or electrochemical methods. The method was also used to synthesize polymers functionalized with carboxylic acid groups without the need for protection/deprotection steps. The resulting polymers can be processed from water or highly polar organic solvents. We also demonstrated a phosphine-free, water-mediated, Pdcatalyzed DAP. The anionic poly(3,4-ethylenedioxythiophenes) were stable in water, and are promising for applications in sensors, drug delivery, and cell engineering. [ABSTRACT FROM AUTHOR]

Pd-catalyzed regioselective C–H arylation is a useful tool for the chemical modification of aromatic heterocycles and 2-arylbenzofuran derivatives are of interest as biologically active substances. Herein, the reaction of triarylantimony difluorides with benzofurans under aerobic conditions in 1,2-DCE, using 5 mol% Pd (OAc)2 and 2 eq. of CuCl2 at 80 °C, produced a variety of 2-arylbenzofurans in moderate-to-high yields. The reaction is sensitive to the electronic nature of the substituents on the benzene ring of the triarylantimony difluorides: an electron-donating group showed higher reactivity than an electron-withdrawing group. Single crystal X-ray analysis of tri(p-methylphenyl) antimony difluoride revealed that the central antimony atom exhibits trigonal bipyramidal geometry.