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[Display omitted] An efficient procedure for the preparation of furo[2,3- c ]-quinolin-4(5 H)-ones from 2-furoic acid N -(o -bromoaryl)- amides via selective intramolecular C(3)–H arylation of the furan nucleus involves the catalysis by a Pd/NHC system generated in situ from Pd(OAc) 2 and readily available IPrSPh HCl proligand. A series of novel furo[2,3- c ]quinolin-4(5 H)-ones were prepared in 65–80% isolated yields. [ABSTRACT FROM AUTHOR]

[Display omitted] Readily available air-stable (NHC)NiCp 2 complexes (NHC is N-heterocyclic carbene, Cp is cyclopentadienyl anion ligand) can be used as efficient thermally activated precatalysts for hydroheteroarylation of olefins with various heteroarenes. According to preliminary mechanistic studies, precatalyst activation may involve reductive elimination of two Cp ligands to give 1,1"-bi(cyclopenta-2,4-diene) and (NHC)Ni0 active species under elevated temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • First report on Pd(II)-catalyzed synthesis of isochromenochromenones possessing spirofused succinimides. • Readily available 3-hydroxy-2-phenyl-chromenones and maleimides are used as the starting compounds. A new annulation reaction is developed for the synthesis of isochromene fused chromenones possessing spiro succinimides scaffold. In this hydroxyl group directed Pd(II)-catalyzed reaction, easily affordable 3-hydroxy-2-phenyl-chromenones and maleimides were used as the coupling partners to synthesize a wide range of the biologically relevant spirocyclic compounds. [ABSTRACT FROM AUTHOR]

• For the first time, the direct carboxylation mechanism of phenol at ZrO 2 is elucidated • The reaction proceeds rather through an Eley Rideal than a Langmuir-Hinshelwood mechanism. • The monoclinic phase is more reactive than the tetragonal one, hence attesting the geometry effect ZrO 2 catalytic properties. • This work is expected to serve as a base for future work related to aromatics carboxylation at metal oxide surfaces. In the present context of environmental concerns, sustainable solutions must be proposed to dispose of waste CO 2 , a well-known greenhouse gas. Among the various emerging projects, upgrading CO 2 molecule into high-value added chemicals appears to be very promising. More particularly, the carboxylation of aromatic compounds to (di-) acid aromatic monomers is of great interest for the high performance polymer industry. Focusing on the direct phenol carboxylation to para -hydroxybenzoic acid as a model reaction, the reactivity of ZrO 2 was investigated in this paper, this material being recently reported in various experimental works for its catalytic efficiency. For the first time, we established the phenol carboxylation mechanism at the surface of a metal oxide material, showing that the reaction can only proceed through an Eley-Rideal mechanism. In this mechanism, CO 2 is strongly chemisorbed at the surface, whereas phenol is physisorbed close to the CO 2 adsorbate. Besides, while the monoclinic and the tetragonal phases often coexist in ZrO 2 particles, we demonstrated that only the monoclinic geometry exhibits a substantial activity. However, the selectivity remains a major challenge, the ortho - isomer being the most abundant product, as in the original Kolbe-Schmitt method. While most of the processes generally reported in literature for the direct carboxylation of phenol are achieved in liquid media, a very few theoretical knowledge is available to describe such a process at solid surfaces. Therefore, we expect the present manuscript to be a pioneer work, aiming at providing a better understanding of metal oxide surface reactivity, paving the road to the rational design of efficient solid catalysts for aromatics carboxylation reactions. While a multistep process (Langmuir-Hinshelwood mechanism) is often proposed in heterogeneous catalysis, at ZrO2 surface the direct carboxylation of aromatics can only proceed via a single step process (Eley-Rideal mechanism). [Display omitted] [ABSTRACT FROM AUTHOR]

The construction of C(sp³)-P bonds is of paramount importance in organic synthesis, catalysis, and materials science. Organophosphorus compounds containing C(sp³)-P bonds serve as pivotal structural motifs in ligands, pharmaceuticals, agrochemicals, and functional materials. While traditional methods for C(sp³)-P bond formation largely rely on nucleophilic substitution or coupling of reactive organometallic reagents, recent years have witnessed significant advancements in metal-catalyzed approaches. This review highlights the recent developments in C(sp³)-P bond formation enabled by metals including Cu, Fe, Bi, Pd, Ni, Ru, Rh, and Co, with particular emphasis on methodologies that activate simple C(sp³)-H bonds or utilize readily available chemical feedstocks. Key mechanistic paradigms, including photoredox/transition metal dual catalysis, metal-catalyzed radical processes, and photo-induced ligand-to-metal charge transfer (LMCT), are critically discussed. This review evaluates the mechanistic insights, applications, and limitations of these methodologies in the synthesis of organophosphorus compounds, and provides perspectives on future directions to promote further advancements in C(sp³)-P bond formation strategies. [Display omitted] [ABSTRACT FROM AUTHOR]

The activation of C(sp 2) H bonds of benzene was achieved by sodium and potassium aluminyls. The products were studied by single-crystal X-ray diffraction showing inverse sandwich structures in which 1,4-dialumination had been achieved. The mechanism was studied using density functional theory, identifying Meisenheimer-type intermediates preceding each activation step. [Display omitted] Under forcing conditions, the aluminyls [AM{Al(NON)}] 2 ([NON]2− = [O(SiMe 2 NDipp) 2 ]2−, Dipp = 2,6- i Pr 2 C 6 H 3 , AM = Na, K) react with benzene to give the 1,4-phenylene di(hydrido)aluminate complexes, AM 2 [1,4-{Al(NON)(H)} 2 (C 6 H 4)]. Crystal structure analysis of the products shows that the 'Al(NON)(H)' groups are in the plane of the para -substituted C 6 -ring, with the alkali metals above and below forming an inverse sandwich structure. Density functional theory calculations were performed to analyse the mechanism leading to the di-substituted product. Results identify a viable dimeric pathway and show that each alumination step is preceded by a Meisenheimer-type intermediate leading to the observed trans -dialuminated product. [ABSTRACT FROM AUTHOR]

This review offers an overview of the synthesis and photoelectric applications of various derivatives of perylene bisimides at different positions, spanning from the imide to bay positions, achieved over the past decade. The synthesis of PBIs involves several routes, including classical methods such as condensation reactions and modern strategies like click chemistry and photochemistry. These methods offer control over the molecular structure, allowing for tailored properties suited for specific applications. In photoelectric applications, PBIs exhibit exceptional characteristics like exceptional photostability, strong absorption within the visible spectrum, and effective charge mobility. These attributes render PBIs excellent candidates for applications such as organic photovoltaics, OLEDs, sensors and organic field-effect transistors. In this review we delve into the development of novel synthetic methodologies, highlighting recent advances in synthetic tools such as C–C coupling and C–H activation. Additionally, the review explores the diverse photoelectric applications of these derivatives, encompassing optical properties, redox behavior, molecular self-assembly, and photo-induced electron transfer characteristics. [ABSTRACT FROM AUTHOR]

[Display omitted] • C-H photooxidation of alkylarenes through charge transfer complex. • Photooxidation of alkylarenes can be performed more efficiently than the corresponding alcohols. • Overoxidation can be avoided via acetal formation in CH 3 CN:MeOH. • Large scale for the production of acids, ketones, and aldehydes. • Co-catalyst (e.g., t-butyl nitrite, nitric acid) free. Here we present a practical, mild, selective, eco-friendly, metal-free, cost-effective, and tunable method for the photoactivation of C-H compounds using an organo photocatalyst without any additives. For this purpose, the organo photocatalyst DDQ was employed as a versatile and highly efficient catalyst for C-H bond functionalization under visible light irradiation in a straightforward reaction setup, free from additives and co-catalysts. Notably, under appropriate solvent conditions, the photooxidation of alkylarenes produced ketones, aldehydes, and carboxylic acids from corresponding starting materials. In CH 3 CN solvent, carboxylic acids were obtained. Interestingly over oxidation to carboxylic acid is avoided and aldehydes were produced from methyl arenes via acetal formation in CH 3 CN:MeOH. Furthermore, our results demonstrated that the photooxidation of 4-methoxytoluene was more efficient than that of 4-methoxybenzylalcohol. The proposed mechanism for this reaction involved the formation of a charge transfer complex between the starting material and DDQ, as indicated by UV–Vis and fluorescence spectra. Also, this method exhibited promising scalability, with 30 mmol of 4-methoxytoluene being converted to 4-methoxybenzoic acid with a yield of 92 % (TON: 345). [ABSTRACT FROM AUTHOR]

Dry reforming of methane (DRM) with CO 2 to syngas can not only reduce the greenhouse gas emissions, but also enrich energy resources. In this study, the performances of the direct and oxygen assisted activation of C–H bond for DRM reaction by Ni(111), Rh/Ni(111) and Rh 6 /Ni(111) were studied based on density functional theory calculations. Doping of Rh to Ni weakened the adsorption strength of the intermediate on the catalyst surface and promoted the activation of C–H bond. The energy barriers of direct dissociation of CH 3 ∗ → CH 2 ∗ + H∗ and CH 2 ∗ → CH∗ + H∗ are much lower than these of oxygen assisted dissociation of CH 3 ∗ + O∗ → CH 3 O∗ and CH 2 ∗ + O∗ → CH 2 O∗ for all the three catalysts, and the optimal reaction path of DRM reaction is CH 4 ∗ → CH 3 ∗ → CH 2 ∗ → CH∗. After formation of CH∗, direct dissociation of CH∗ → C∗ is easier to happen on Ni(111) surface compared to Rh/Ni(111) and Rh 6 /Ni(111) surfaces. However, CH∗ favores the oxygen assisted dissociation of CH∗ + O∗ → CHO∗, which prevents the resistance to carbon depositions. [Display omitted] • C–H activation for DRM reaction over Rh–Ni catalyst was well-established by DFT calculations. • Doping of Rh to Ni weakened the adsorption strength and promoted the activation of C–H bond. • Direct dissociation of CH x ∗(x = 1–3) had lower energy barriers than O∗ assisted dissociation. • Rh–Ni catalysts significantly prevented carbon depositions compared to the Ni catalyst. [ABSTRACT FROM AUTHOR]

We present an approach for ortho C(sp2)-H acylation and intramolecular amination reactions, employing 4-amino-benzotriazole (ABTA) as a bidentate directing group. This method is facilitated by a palladium catalyst in combination with iodobenzene diacetate. Our approach efficiently yields acetoxylation and intramolecular amination products from a variety of acylamide substrates, including arylcarboxamides and arylacetamides. [Display omitted] • Utilize a novel directing group (ABTA). • Effectively activate both C(sp2)-H and C(sp3)-H bonds. • Good yield and selectivity to obtain acetoxylation and intramolecular amination products. • ABTA directing group was removed easily. [ABSTRACT FROM AUTHOR]

Over the past few decades, the field of transition metal-catalyzed selective C–H functionalization has made significant strides in enabling the synthesis of diverse organic compounds. These advancements in C–H functionalization techniques have paved the way for the efficient introduction of various functional groups to distal aromatic C(sp2)-H bonds under mild reaction conditions. This review highlights the progress made in the selective functionalization of aromatic C(sp2)-H bonds in 2-phenyl-4 H -benzo[ d ][1,3]oxazin-4-ones via transition metal-catalyzed C–H activation. Key features of the review include a detailed discussion on how substituents affect C–C, C–O, C–N, and C-X (X = Cl, Br, I) bond formation at the ortho C(sp2)-H position of 2-phenyl-4 H -benzo[ d ][1,3]oxazin-4-ones, along with a deeper exploration of the mechanistic studies. This review provides a succinct overview of the recent accomplishments in controlled functionalization of aromatic C(sp2)-H bond of 2-phenyl-4H-benzo[d][1,3]oxazin-4-ones, one of the most valuable pharmaceutically active heterocyclic molecules, with directing group assistance strategy using transition metal-catalyzed C–H activation approaches. [Display omitted] [ABSTRACT FROM AUTHOR]

• Pd NPs@Cu 2 (BDC) 2 DABCO as heterogenous catalyst for the synthesis of diaryl ketones via C H activation. • Mild reaction condition and easily work-up of the products. • Reusability of the catalyst without significant loss of catalytic activity after four runs. In this research, Pd@Cu-MOF is used as a reusable heterogeneous catalyst to develop a unique approach for the synthesis of diaryl ketones via C H activation reaction of aryl aldehydes and arylhalides with good yield. Pd nanoparticles encapsulated in the metal-organic framework (Pd@Cu 2 (BDC) 2 DABCO) and the structure of the catalyst was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), BET, transmission electron microscopy (TEM). The catalyst was recycled and reused four times without significant loss of activity. A plausible mechanism is provided and the chemical structures of the synthesized compounds were confirmed by comparison of their melting points with literature and 1HNMR spectra. [ABSTRACT FROM AUTHOR]

Inert C–H bonds are present in a plethora of bioactive and pharmaceutical compounds. Activating otherwise inert C–H bond has emerged as a versatile tool for sustainable organic synthesis. The catalytic potential of C–H bond activation by second and third-row-based metal catalysts has been well documented. In the last decade, the first row-based metal catalyst for C–H activation has emerged as a transformative platform and setting a benchmark. Manganese catalysis, due to its abundance, non-toxic nature, low cost and variable oxidation states (−3 to +7) has become a rapidly growing area of research interest in recent years. Over the past years, many reviews have been published regarding Mn-catalyzed functionalization but in this review a particular attention has been made on the transformation of C–H bond. Summarizing reports from January 2018 to August 2024, this review aims to guide the potential of Mn catalysts for future developments. [Display omitted] • The review explores the wide array of manganese catalysts employed in various C–H activation reactions, shedding light on their design, efficiency, and reaction scope. •Manganese's capacity for oxidative addition and reductive elimination enables the direct transformation of inert C–H bonds into valuable chemical entities. Its electronic and steric properties significantly influence regioselectivity, offering precise control over reaction outcomes. •The review emphasizes the untapped potential of Mn, which, due to its abundance and affordability, presents a promising alternative for catalytic applications, particularly in C–H activation processes. [ABSTRACT FROM AUTHOR]

The selective photocatalytic oxidative coupling of methane (OCM) holds great potential in converting low-cost feedstock into C 2 products. However, the challenge lies in improving the photocatalytic OCM activity through catalyst design and gaining a deeper understanding of reactant activation in the OCM process. Here, we synthesized Au-ZnSn-LDH with oxygen vacancies to achieve efficient selective oxidation of methane using O 2. The optimal hybrid exhibits a C 2 H 6 yield of 2666 μmol g−1 h−1 and 76.8 % selectivity. Our findings showed that the oxygen within the surface of ZnSn-LDH (possibly from adsorption at O v vacancy sites) provides sites for the evolution of O 2 to O 2 − with assistance from Au cocatalyst. More O 2 − could be generated from O 2 provides a desired reactivity to selectively promote selective C−H activation of CH 4 under photoexcitation. The Au cocatalyst plays crucial roles in facilitating the methyl transfer and promoting C−C coupling to produce C 2 H 6 as the main product while avoiding undesirable overoxidation. [Display omitted] • Au-loaded ZnSn-layered double hydroxides with a defect structure were synthesized. • The hybrid enables the oxidative coupling of methane through directional activation of oxygen. • The involvement of O 2 − radical is essential for facilitating the selective C−H activation of CH 4. • The presence of Au cocatalyst and O v vacancies ensures a high-rate conversion of CH 4 to C 2 H 6. [ABSTRACT FROM AUTHOR]

The present study explores the potential of six NHC-palladium(II) complexes derived from 1-cinnamyl- N -alkylbenzimidazolium salts, namely trans -dichloro[1,3-dicinnamyl-benzimidazol-2-yliden]pyridine palladium(II) (3a), trans -dichloro[1-cinnamyl-3-benzyl-benzimidazol-2-yliden]pyridine palladium(II) (3b), trans -dichloro[1-cinnamyl-(fluorobenzyl)-benzimidazol-2-yliden]pyridine palladium(II) (2-fluorobenzyl 3c , 3-fluorobenzyl 3d and 4-fluorobenzyl 3e ,) and trans -dichloro[1-cinnamyl-(4-nitrobenzyl)-benzimidazol-2-yliden]pyridine palladium(II) (3f), as precatalyst for the cross-coupling reactions between furanyl and thiofuranyl derivatives and arylbromides via C–H activation of the heterocycles. The structure of the six palladium(II) complexes has been elucidated through the use of multinuclear NMR, FT-IR and mass spectroscopy. Furthermore, the square-planar geometry of the organometallic ion was confirmed by single crystal X-ray diffraction study carried out on complex 3c. The latter complex proved to be the most effective precatalyst agent, with observed conversions higher than 78 % when 4-bromoacetophenone and 1-bromonaphthalene were employed. [Display omitted] The present study explores the potential of six NHC-palladium(II) complexes derived from N -cinnamyl- N' -alkylbenzimidazolium salts, namely trans -dichloro[1,3-dicinnamyl-benzimidazol-2-yliden]pyridine palladium(II) (3a), trans -dichloro[1-cinnamyl-3-benzyl-benzimidazol-2-yliden]pyridine palladium(II) (3b), trans -dichloro[1-cinnamyl-(fluorobenzyl)-benzimidazol - 2-yliden]pyridine palladium(II) (2-fluorobenzyl 3c , 3-fluorobenzyl 3d and 4-fluorobenzyl 3e ,) and trans -dichloro[1-cinnamyl-(4-nitrobenzyl)-benzimidazol-2-yliden]pyridine palladium(II) (3f), as precatalyst for the cross-coupling reactions between furanyl and thiofuranyl derivatives and arylbromides via C H activation of the heterocycles. The structure of the six palladium(II) complexes has been elucidated through the use of multinuclear NMR, FT-IR and mass spectroscopy. Furthermore, the square-planar geometry of the organometallic ion was confirmed by single crystal X-ray diffraction study carried out on complex 3c. The latter complex proved to be the most effective precatalyst agent, with observed conversions higher than 78% when 4-bromoacetophenone and 1-bromonaphthalene were employed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effective synthesis of branched and linear allyl arenes. • Excellent E/Z selectivity and regio-selectivity. • Easily available starting materials, mild and redox-neutral reaction conditions. Presented herein is an effective synthesis of branched and linear allyl arenes based on the reactions of 2-aryl-3 H -indoles with 5-methylene-1,3-dioxan-2-one or 4-vinyl-1,3-dioxolan-2-one. Mechanistically, the reactions are initiated by Rh(III)-catalyzed aryl C(sp2)–H bond activation/cyclometallation followed by vinyl coordination/migratory insertion and β–O elimination through release of CO 2 as the only by-product. By using this newly developed protocol, a group of 2-aryl-3 H -indole derivatives bearing the substructure of either branched or linear allylic alcohol were obtained in good efficiency. Notably, the linear allylic alcohols were obtained with excellent E/Z selectivity when unsubstituted vinyl-1,3-dioxolan-2-one was used as the allyl surrogate. With advantages such as easily available starting materials, mild and redox-neutral reaction conditions, good compatibility with a broad range of functional groups, benign solvent and divergent products, this protocol is expected to be used in the synthesis of indole-based functional molecules. [ABSTRACT FROM AUTHOR]

[Display omitted] • ortho -directed C H benzoxylation of simple 2-phenyl quinazolinones with palladium assistance has been developed. • Ceric ammonium nitrate, a potent single-electron oxidizing agent, was employed as an oxidant. • Simple and readily accessible aromatic carboxylic acids were utilized as a source of benzoxylate. • A one-pot method exhibiting great regioselectivity with good to modest yields. A simple protocol for a regioselective cross dehydrogenative reaction of 2-aryl-quinazolinones with different phenyl carboxylic acids was developed using a palladium catalyst facilitated by C H activation. Simple and readily accessible aromatic carboxylic acids were utilized as a source of benzoxylate. A one-pot method proceeded with great regioselectivity and offered mono benzoxylation product with moderate to excellent yield. [ABSTRACT FROM AUTHOR]

[Display omitted] • This article reports a mild system catalyzed by ligand free palladium, which promoted the ortho -aromatization of benzoic acid under mild conditions for 36 hours and achieved excellent results. • Under this reaction condition, not only is there no decarboxylation byproduct, but also the ortho substituted benzoic acid is obtained with good yield. • The catalytic system has simple operation and mild conditions. It is particularly significant to develop mild and efficient methods to construct 2-aryl-substituted benzoic acids framwork due to their wide existence in many important natural organic compounds. Here, we report a concise and mild method to synthesize ortho -arylation of benzoic acids. In this mild catalytic system, decarboxylation byproducts were not observed. Meanwhile, the high yields could be obtained in the absence of ligands. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of isoquinolines via Cp*Co(III) catalyzed reaction of benzimidates with sulfoxonium ylides. • The reaction features simple operation, broad substrate scope, and good functional group tolerance. • 31 examples of products in 43 % to 85 % yields. A practical and highly efficient method for the regioselective synthesis of isoquinolines was developed via cobalt-catalyzed C(sp2)−H activation and subsequent intramolecular tandem annulations between benzimidates and sulfoxonium ylides. Key to the success of this transformation was the use of an inexpensive and bench-stable Cp*Co(III)-catalyst. Various functionalized isoquinolines were prepared successfully under base-free and oxidant-free conditions. This protocol features simple operation, broad substrate scope, and good functional group tolerance. Moreover, the reaction is scalable and tolerant of ambient air and moisture. [ABSTRACT FROM AUTHOR]

[Display omitted] • Reduced Ni-MgO catalysts were characterized by Ni0 species stabilized by Ni2+. • High crystalline MgO support can retain more Ni0 species on the surface. • The moderate MSI exhibits improved spatial distribution of Ni0. • The HCO 2 * converted rapidly at the rich Ni0/Ni2+ site can promote the activity. To deeply explore the key role of Ni species over highly active Ni-MgO catalysts for the dry reforming of methane (DRM) is still a great challenge. This study presents a Ni-MgO catalyst with a high proportion of active Ni0 species stabilized by Ni2+ (Ni0/Ni2+ site) by electron transfer from Ni0 to Ni2+, which demonstrates remarkable DRM performance, even operating at a high temperature of 750 °C for 200 h. Compared with the Ni-MgO catalysts with strong interaction between Ni species and MgO, the Ni-MgO catalyst with moderate interaction between Ni species and highly crystalline MgO exhibits superior thermal stability, resulting in the high proportion Ni0/Ni2+ sites and the improved spatial distribution of Ni0. TPSR results show that the activation temperatures of CH 4 were obviously decreased (∼100 °C) over the Ni-MgO catalyst with abundant Ni0/Ni2+ sites. Interestingly, the abundant mid/strong base sites that existed on Ni-MgO with a high proportion of Ni0/Ni2+ sites can restrain the carbon deposition due to the increased CO 2 adsorption ability in the DRM reaction. The formate (HCOO*) pathway was validated by in situ DRIFTS, indicating that the plentiful Ni0/Ni2+ sites promoted the activation of HCO 3 * into HCOO*, and then generated H 2 and CO. This study provides a comprehensive understanding of the relationship between the Ni species on MgO and the reaction pathway in dry reforming of methane. [ABSTRACT FROM AUTHOR]

[Display omitted] An efficient method for the selective preparation of trifluoro-methyl-substituted isoindolones has been developed via RhIII catalyzed C-H activation / [4 + 1]-annulation of aryl hydroxamates with functionalized acceptor/acceptor diazo compounds as cross-coupling partners. [ABSTRACT FROM AUTHOR]

• A copper-based electrode was utilized as the catalyst in sonogashira C-H activation coupling reactions. • This electrode was used for electro-oxidation synthesis of diphenylethyne derivatives. • The successful synthesis of diphenylethynes was achieved with high yields. In recent years, there have been significant advancements in Copper-catalyzed Sonogashira coupling reactions, employing both traditional and electro-oxidation methods for synthesizing diphenylethyne derivatives. This study focuses on the progress achieved through the utilization of copper foam electro-catalyzed Sonogashira coupling reactions in the synthesis of diphenylethyne derivatives 4(a-q) and provides insights into the future prospects of this field. The paper emphasizes the development of efficient copper foam catalysts, the optimization of reaction conditions, and potential applications of electro-oxidation reaction copper-catalyzed Sonogashira coupling in various fields, including materials chemistry and organic synthesis. The integration of electro-oxidation reactions into copper-catalyzed Sonogashira coupling reactions presents a promising approach for the efficient synthesis of diphenylethyne derivatives. The future trajectory of this field involves further advancements in catalyst design, reaction optimization, and the exploration of new applications for diphenylethyne derivatives across diverse scientific disciplines. This investigation specifically explores the electro-oxidation process of the Sonogashira reaction, utilizing a copper foam cathode and graphite anode in isopropyl alcohol (iPrOH) as the solvent and weak base. Sodium bromide (NaBr) serves as an economical and readily available electrolyte and reagent under green and sustainable conditions. The successful synthesis of a variety of diphenylethyne derivatives 4(a-q) was achieved, with notable yields ranging from 83% to 92%. [Display omitted] [ABSTRACT FROM AUTHOR]

• Six palladium(II) (3a-f) complexes of the type [Pd2(μ-Cl)2(NHC)] were prepared by transmetallation of the corresponding Ag-NHC and [PdCl2(CH3CN)2] complexes, and their structures were successfully characterised by 1H NMR, 13C NMR, HRMS, FTIR and elamantal analysis. Density functional theory (DFT) calculations were also realised for the complexes. • The prepared complexes were assessed for their catalytic activity in the C-H arylation of 2-isobuthylthiazole as well as for their biological activities. As results, these complexes were found to be potent catalysts in the creation of C5-arylated 2-isobuthylthiazole derivatives via C-H bond activation reaction. • Furthermore, biological activity analysis revealed that complex 3a exhibits high cytotoxicity towards both human colon carcinoma cell lines (HCT-116) and hepatocellular carcinoma cell lines (HepG-2) with IC50 values of 4.2 and 9.3 μMmL-1, respectively. Six palladium(II) (3a-f) complexes of the type [Pd 2 (μ-Cl) 2 (NHC)] were prepared by transmetallation of the corresponding Ag-NHC and [PdCl 2 (CH 3 CN) 2 ] complexes, and their structures were successfully characterised by 1H NMR, 13C NMR, HRMS, FTIR and elemental analysis. Density functional theory (DFT) calculations were also realised for the complexes. The prepared complexes were assessed for their catalytic activity in the C-H arylation of 2-isobuthylthiazole as well as for their biological activities. As results, these complexes were found to be potent catalysts in the creation of C5-arylated 2-isobuthylthiazole derivatives via C-H bond activation reaction. Furthermore, biological activity analysis revealed that complex 3a exhibits high cytotoxicity towards both human colon carcinoma cell lines (HCT-116) and hepatocellular carcinoma cell lines (HepG-2) with IC 50 values of 4.2 and 9.3 µMmL−1, respectively. Complex 3b also showed antioxidant activity comparable to that of BHT through DPPH and ABTS assays. Both complexes 3d and 3f also showed significant inhibitory activity towards the AChE enzyme with IC 50 values of 5.06 and 2.52 µMmL−1, respectively. Finally, all complexes showed excellent antiparasitic activity, with 3b exhibiting strong antileishmanial activity against both L. major promastigotes and amastigotes. The interaction between the most cytotoxic complexes and DNA, envisaged as a potential mechanism of toxicity, was explored by means of docking studies. In summary, these prepared complexes have the potential to serve as potent catalysts for the synthesis of arylated 2-isobutylthiazole and biologically active agents, paving the way for numerous prospects in the fields of medicinal chemistry and organic synthesis. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] A mild and efficient catalytic method for the iodination of benzoic acids has been explored. The catalytic system comprising [RhCp*Cl 2 ] 2 and PhI(OAc) 2 allowed the ortho -selective iodination products in the absence of any additive or base. This protocol features relatively broad substrate scope and operational simplicity. Air and moisture are also well tolerated. Importantly, readily available and cheap potassium iodide served as iodinating reagent. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni SAs in Zn3In2S6 alter benzyl alcohol photoreforming activity and selectivity. • Improved carrier dynamics by Ni SAs in Zn3In2S6 elevates photoreforming activity. • Ni SAs in Zn3In2S6 suppress C-C coupling and promote benzaldehyde formation. • Ni SAs in Zn3In2S6 induce facile O-H activation post C-H activation, altering selectivity. Photoreforming enables simultaneous H 2 production and organic synthesis in a one-pot system. In this study, a single-step synthesis approach was employed to fabricate atomically dispersed Ni in Zn 3 In 2 S 6 (Ni x ZIS) for benzyl alcohol photoreforming. While neat ZIS exhibits high selectivity toward hydrobenzoin via C-H activation and C-C coupling, its H 2 evolution rate remains below feasible levels. Incorporating Ni single atoms significantly enhances ZIS activity by improving the carrier dynamics, resulting in an optimal H 2 evolution rate of 9.13 mmol g−1 h−1 on Ni 4 ZIS, over five times higher than neat ZIS. The presence of Ni single atoms also alters selectivity, suppressing C-C coupling products and promoting benzaldehyde generation. The Ni single atoms induce facile O-H activation following the C-H activation of benzyl alcohol on ZIS, inhibiting the desorption of carbon radicals and causing consecutive oxidation to benzaldehyde. This study elucidates the role of Ni single atoms in driving activity and selectivity during organic photoreforming. [ABSTRACT FROM AUTHOR]

The iron-hydroxo species called compound II in conversion of lidocaine analogs into imidazolinones show a secondary selective hydrogen abstraction, which is related to the spin state of the active center and the specific structure of the organic compound. This selectivity is well described by electron spin density isosurface and is a hydride transfer mechanism other than hydrogen atom abstraction process. [Display omitted] • The spin state of Compound I and the substrate's structure jointly determine the selective activation of the C H bond. • The selective H-abstraction is well elucidated by the spatial orientation and electron spin density isosurface. • The study of mechanisms can offer valuable insights for the design and synthesis of organic compounds. The regio- and stereo-selectivity activation of C H bond catalyzed by CYP450 has attracted much attention due to its high efficiency. In these reactions, a pair of high-valent iron-oxo and iron-hydroxo species called compound I (Cpd I) and II (Cpd II) are the main intermediates. Studies on the conversion of lidocaine analogs into imidazolinones reveal that the cyclization process, whether it involves a one-step hydrogen abstraction mediated by Cpd I or a secondary selective hydrogen abstraction facilitated by Cpd II, is contingent upon the spin state of the P450 active center and the specific structure of the organic compound. Based on the research findings, it is suggested that inserting a carbon atom at a specific position to elongate the carbon chain length represents an effective approach for producing piperazinone. The mechanistic investigation can offer valuable insights for the rational design of organic compounds and facilitate a deeper comprehension of P450. [ABSTRACT FROM AUTHOR]

A proficient approach has been developed for the synthesis of substituted 2 H -chromenes from C1-substituted glucal. The key step of our synthetic methodology was C–H activation in propylene carbonate solvent followed by 6 π- electrocyclization aromatization in ethylene glycol as greener substitutes to toxic aprotic solvents, to obtain 2 H -chromenes in a stepwise manner. The application of the developed methodology was further explored with the synthesis of a small library of substituted 2 H -chromenes in good yields. [Display omitted] • Synthesis of substituted 2 H -chromenes from d -mannose. • 6 π- electrocyclization aromatization in ethylene glycol. • Utilization of green solvents and gram-scale synthesis. [ABSTRACT FROM AUTHOR]

Hexahydro-1,3,5-triazines are often used as formaldimine precursors. The recent success of Sun et al. (Angew. Chem. Int. Ed., 2016, 55 , 11867) in achieving gold-catalyzed [4 + 1]/[4 + 3] annulations of hexahydro-1,3,5-triazines with diazo esters, in which the hexahydro-1,3,5-triazine is directly used as the 1,4-dipole in the annulation, represents a breakthrough in mechanistic studies. In the present work, density functional theory (DFT) calculations were used for detailed investigation of possible catalytic mechanisms. The proposed catalytic cycle involves five major stages: dinitrogen elimination to form a gold–carbene intermediate; diazoacetate–hexahydro-1,3,5-triazine C–C coupling to give an ammonium ylide; ring opening of the hexahydro-1,3,5-triazine via C–N single-bond cleavage; a second C–N single-bond cleavage; and C–C-bond-forming reductive elimination. The regioselectivities of the cycloaddition of hexahydro-1,3,5-triazines with enol diazoacetates differ from those of cycloadditions with vinyl diazoacetates. The calculations also clarified the origins of the substrate-controlled regioselectivity. Image 1 • Origin of substrate-controlled regioselectivity was clarified. • Novel reaction mechanism for the hexahydro-1,3,5-triazine was exploited. • Second gold is important in facilitating the reaction. [ABSTRACT FROM AUTHOR]

An efficient, scalable synthetic method of chromeno[3,4- c ]pyridine scaffolds through redox-neutral [4 + 2] annulation between coumarinyl ketoxime esters and internal alkynes has been developed using the rhodium(III) catalytic system. The present transformation proceeds under mild conditions, features good functional group compatibility and obivates the use of external oxidants. Ready access to pyridine derivatives bearing three carbon substituents is exemplified. Image 1 • Efficient & scalable synthesis of chromenopyridines. • Redox-neutral annulation. • Oxime acetates as internal oxidant. • Diversified derivatization. • Easy late-stage functionalization. [ABSTRACT FROM AUTHOR]

• Recent developments in organic electronics were allowed by access to new materials. • Many such compounds are prepared by transition metal (TM)-catalyzed cross-couplings. • C–H activation protocols are often more sustainable than traditional cross-couplings. • Examples of both processes are presented, organized according to the reaction type. Cross-coupling reactions have played a key role in producing numerous types of π-conjugated small molecules having appealing properties for practical applications in organic electronics, especially in the field of photovoltaics. The main advantages of such synthetic methodology are the compatibility with many types of functional groups and the flexibility which allows an easy way to introduce diversity and tune the electronic and photophysical properties of the target molecules. As a result, many semiconducting and photoactive organic compounds have been synthesized using this powerful tool. In this paper we will highlight a number of selected syntheses and optimized C–C bond formation processes described in the years 2000–2018 and related to this specific field, choosing those examples which can demonstrate the enormous power of the cross-coupling processes, but also the room for improvements of these methodologies. [ABSTRACT FROM AUTHOR]

• The complicated surface chemistry of TM ceramics may be stemmed from their compositional complexity and flexibility. • An orbital overlap effect were found to dictate several aspects of TM ceramic surface chemistry. • First row TM ceramics are generally less reactive and exhibit more stable surface composition under a reducing environment. • The reduced bonding strength within the 2nd/3rd row TM ceramics led to less stable surface composition and more reactive surface reaction sites. • The distortion energy may indicate specific electronic features in certain materials that may be catalytically useful, e.g., larger C–H bond elongation. Controlling the surface chemistry of catalysts towards unsaturated carbon-carbon bonds is vital to achieving many contemporary chemical transformations. Transition metal (TM) ceramics are promising materials that exhibit lower and tunable surface reactivity towards C=C bonds. Herein, we have employed an analysis of the adsorption of benzene over a large suite of TM ceramic and pure metal surfaces to benchmark a large selection of materials to isolate trends. Results showed a wide range of surface reactivity as a function of the constituent elements, surface composition, TM-to-p-element ratio, surface ensemble size, electronic structure, etc. The 1st row TM ceramics exhibited lower surface reactivity and more stable surface composition than the 2nd/3rd TM ceramics suggesting that orbital-size match could be a simple marker for predicting general surface chemistry and surface composition stability in TM solid compounds. The TM-to-p-element ratio also generally dictated metal-like or markedly-modified reactivity of the constituent elements at the ceramic surface. Electronic analysis further quantified the correlation between the density and type of electronic states near the Fermi level and the reactivity of surface-lattice elements. Structural and energetic analysis of the adsorbed benzene indicated the activation of the adsorbate could be better quantified beyond simple adsorption energy. [ABSTRACT FROM AUTHOR]

[Display omitted] • The disorder engineering of TiO2 through phase-selective reduction to enhance the absorption of visible light. • The anatase crystalline structure for adsorptivity of organic reactants. • The phase-mixed ordered anatase and disordered rutile TiO 2 for the photocatalyzed direct C-H arylation. To understand and modify TiO 2 for organic photoreaction, two points are important: improving light absorption and retaining adsorption sites for organic reagents. Herein, we tuning the absorption and adsorption of TiO 2 by introducing the defects on each phase of TiO 2 , called phase-mixed structures of ordered anatase (OA) and disordered rutile (DR) (OA/DR P25) and disordered anatase (DA) and ordered rutile (OR) (DA/OR P25). Disordered structure of TiO 2 broadened the absorption wavelength range including visible light, but changed surface structure reduced the adsorptivity of organic reactant. Additionally, anatase and rutile phase of TiO 2 has different surface properties and energy band structure, so keeping the crystalline anatase surface for adsorption was important while introducing the TiO 2. Thus, it is assumed that the phase combination of OA and DR can be the best photocatalytic structure of TiO 2 even without any supporting materials and/or co-catalysts. In fact, the arylation yield of OA/DR P25 is the highest (63.4%), compared to those of untreated P25 (40.0%) and DA/OR (20.1%), highlighting the potential of OA/DR P25 in various visible light-driven photocatalytic organic reactions. [ABSTRACT FROM AUTHOR]

An account of our previously disclosed total synthesis of the aryltetralin lignan natural product podophyllotoxin, a building block used in the synthesis of the FDA-approved anticancer drug etoposide, is disclosed. A C–H activation disconnection was viewed as being amenable to the preparation of E-ring modified analogs but proved challenging to execute. Various insights into palladium-catalyzed C–H arylation reactions on complex scaffolds are reported ultimately leading to the implementation of this strategy and the synthesis of compounds inaccessible by semisynthetic means. Image 1 [ABSTRACT FROM AUTHOR]

An efficient rhodium-catalyzed direct C-H activation for the synthesis of isoquinolone with 1,4,2-dioxazol-5-ones as oxidizing directing groups have been developed, which featured mild reaction conditions, short reaction time and satisfactory yield. An efficient approach to isoquinolone have been developed, which featured in completing expeditiously under mild conditions with satisfactory yield. Image 1 [ABSTRACT FROM AUTHOR]

Bioinspired chiral iron(II) complex [((R)-(−)-N4Py*)FeII(CH 3 CN)]2+ (1) (N4Py* = N , N -bis(2-pyridylmethyl)-1,2-di(2-pyridyl)ethylamine) has been shown to efficiently catalyze the benzylic C H oxidation of ethylbenzene with tert -butyl hydroperoxide (TBHP), H 2 O 2 , and meta -chloroperoxybenzoic acid (mCPBA) resulting in enantiomerically enriched 1-phenylethanol up to 12.5% ee and the corresponding acetophenone, where the [FeIV(N4Py*)(O)]2+ (2) intermediate has been detected by UV/Vis spectrometry. The stoichiometric oxidation of benzyl alcohol and various hydrocarbon derivatives including the asymmetric hydroxylation of ethylbenzene with 2 has also been investigated. Detailed kinetic, and mechanistic studies (kinetic isotop effect (KIE) of 31 and 38, and Hammett correlation with ρ = −0.32 and −0.98 for PhCH 2 OH and PhCH 3 , respectively, and the linear correlation between the normalized bimolecular reaction rates and bond dissociation energies (BDE CH)) lead to the conclusion that the rate-determining step in these reactions above involves hydrogen-atom transfer between the substrate and the Fe(IV)-oxo species. The stoichiometric 2 -mediated hydroxylation of ethylbenzene affords 1-phenylethanol in up to 33% ee , suggesting clear evidence for the involvement of the oxoiron(IV) species in the enantioselective step. The moderate enantioselectivity may be explained by the epimerization of the long-lived substrate radical before the rebound step (non-rebound mechanism, where k ep > k reb). The kinetic resolution of the resulting chiral alcohol due to its metal-based overoxidation process into acetophenone in the catalytic metal-based ethylbenzene oxidation can be excluded. The reactivity of oxoiron(IV) complex, [FeIV(asN4Py)(O)]2+ with chiral pentadentate ligand, has been investigated in the oxidation of various hydrocarbons and alcohols. Unlabelled Image • Catalytic ethylbenzene oxidation with chiral Fe(II)-polypyridyl complex • Evidence for the formation of oxoiron(IV) intermediate (oxidant) • Oxoiron(IV)-mediated C H activation of benzyl alcohols and hydrocarbons • Reaction kinetics with UV–Vis spectroscopy • Oxoiron(IV)-mediated enantioselective oxidation [ABSTRACT FROM AUTHOR]

Abstract We report a rhodium-catalyzed ortho C(sp 2)-H borylation of 2-phenylpyridines using commercially available N-heterocyclic carbenes (NHCs) as ligand and pinacolatodiboron (B 2 pin 2) as borylating reagent. The reaction could take place at room temperature, tolerating a wide range of functionalities and affording ortho borylated products in moderate to excellent yields. The current method is also applicable to gram-scale reaction with reduced catalyst loading. Graphical abstract Image 3 [ABSTRACT FROM AUTHOR]

Abstract In this paper, we report the assembling of libraries of β -arylated short/medium/long chain-based non- α -amino acid (aminoalkanoic acid) derivatives via the Pd(II)-catalyzed, bidentate directing group 8-aminoquinoline-aided sp3 β -C-H activation/arylation method. Short/medium chain-based unnatural amino acid derivatives containing an aryl group at the β -position are promising small molecules with therapeutic properties. Thus, it is necessary to enrich the libraries of short/medium/long chain-based unnatural amino acid derivatives containing an aryl group at the β -position. Considering the importance of β -arylated short/medium/long chain-based non- α -amino acid derivatives, an inclusive attention was paid to explore the Pd(II)-catalyzed sp3 β -C-H arylation of short/medium/long chain-based non- α -amino acids. Representative synthetic transformations including a short route for the assembling of rolipram and related compounds and 3-arylated GABA derivatives such as, baclofen, phenibut and tolibut were shown using selected β -C-H arylated non-α-amino acid derivatives. Graphical abstract Image 1 [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]

Abstract An unprecedented Rh(III)-catalyzed C–H activation of N -(pivaloyloxy)benzamide was recently reported by Feng et al. In this transformation, the substituent on the alkyne controls the chemoselectivity (annulation or hydroarylation). Given the importance of this novel strategy, we performed a density functional theory study to clarify the origins of the experimentally observed chemoselectivity. The results of our calculations showed that the conventional annulation of N -(pivaloyloxy)benzamide with an alkynone was kinetically favored, whereas the hydroarylation of α,α-difluoromethylene alkynes was kinetically favored. We found that the inductive effect of a fluorine substituent on the alkyne polarizes the Rh–C bond, and this facilitates the protonation step. Our calculations also explain the experimentally observed regioselectivity, which mainly arises from the interaction energy. Graphical abstract Image 1 Highlights • Origin of substituent-controled chemoselectivity (annulation or hydroarylation) was clarified. • Experimentally observed regioselectivity was explained. • Fluorine substituents in alkyne play an essential role in diverting the reaction sequence from the conventional pathway. • Protonation of the alkenyl group precedes formation of a Rh(V) nitrenoid intermediate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Use of non-toxic/least toxic chemicals. • Generation of least studied ester-linked covalent organic polymer. • Crystalline nanosheet generation (average crystallite size = 43.5 nm, crystallinity = 90.5 %). • Excellent photocatalytic activity with high selectivity for C-H activation and C-C bond formation reaction. Among all polymeric materials, the chemistry of covalent organic polymers has been the least covered in the field of photocatalysis due to the rare availability of design and synthetic protocols. In the present work, we have come up with an efficient design of a one-dimensional Covalent Organic polymer (COP) (S-COP) through the ester-linked co-polymerization of Erythrosine B with 2,2′-Dithiodibenzoic acid (2,2′-DDB). The COP was synthesized via the facile one-pot solvothermal method. The XRD data analysis favors high crystalline nanoscale polymeric sheet generation (S-COP , 90.5 % & 43.5 nm). The HOMO-LUMO calculation through an electrochemical study as well as Tauc's plot showed 2.1 eV band gap. In this order, S-COP , a metal-free polymeric material was observed as an effective photocatalyst in the solar-driven photocatalytic reaction of heteroarenes with aryl diazonium salts via direct C-H arylation (High yield (∼98 %), and high selectivity (∼98 %)). [ABSTRACT FROM AUTHOR]

Isocoumarin has been recognised as one of the most privileged heterocyclic motifs for the development of numerous natural product-inspired biologically important compounds. Due to the diverse biological activities of isocoumarins and their role as a pivotal intermediate in synthetic organic chemistry, continuous efforts are devoted towards its synthesis via either traditional or metal-catalyzed reactions. The metal complexes of palladium, copper, rhodium, ruthenium, iridium, nickel, zinc and silver are being frequently utilized for the construction of the isocoumarin scaffolds. Among the traditional methods, electrophilic cyclizations, halo-lactonizations are well known methodologies for the development of isocoumarins. This systematically and critically analysed review highlights recent developments in the synthesis of isocoumarin derivatives with plausible reaction mechanisms, their natural occurrence and pharmacological importance, together with their potential applications in medicinal chemistry as active pharmaceutical agents. In this review, the recent developments in synthesis of biologically important isocoumarin derivatives with plausible reaction mechanisms, their natural occurrence and pharmaceutical importance along with their applications in various fields have been discussed. [Display omitted] [ABSTRACT FROM AUTHOR]

Crown ethers consisting of several ether linkages (R–O–R′) have been attracting attention in the fields of inorganic and organic chemistry, attributed to their cavity sizes and superior cation selectivity. However, they exhibit comparatively low selectivity and ion-binding affinities due to their structural flexibility. Recent studies have shown that crown ethers rigidly formed within 2D matrices, e.g., graphene, exhibit enhanced binding energy and selectivity. However, most of these studies were based on computational modeling and simulations. In this study, the synthesis of crown-ether-embedded graphene was attempted for the first time by the solution plasma process (SPP). Crown-ether-embedded graphene was successfully synthesized through C–H activation and polymerization reactions between as-produced intermediates (i.e., polycyclic aromatic hydrocarbons, including multiply fused benzene rings) and activated cation radicals. Structural and chemical analyses were conducted to verify the existence of the crown ether structure (cyclic ether, C–O–C) in the carbon matrix, and a 2D graphene structure with a cavity originating from the crown ether was observed by transmission electron microscopy analysis. Moreover, adsorption test confirmed successful synthesis of crown ether-embedded graphene with ordered cavity size. We believe that the proposed synthesis approach for crown ether-embedded graphene will be valuable for a wide range of applications, such as ion-selective membrane applications and waste cleanup. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • New iridium complexes of acridine-based PNP-type pincer ligands are introduced. • Synthesis involved intramolecular C H activations and additions of H 2 and NaBEt 3 H. • The pincer ligands are flexible and capable of both mer - and fac -coordination. • These ligands support metal-centered reactions, i.e., C H and H H activation. • Hydride- and H 2 -induced dearomatization of the acridine moiety is also feasible. Acridine-based PNP-type pincer ligands (AcrPNP) have previously been used for the construction of a small number of Ru(II), Mn(I), Rh(III) and Ir(III) complexes, with most attention being given to the catalytically-active ruthenium complexes. In the present work, we significantly expand the scope of known AcrPNP complexes by introducing a series of new Ir(I) and Ir(III) complexes. These were synthesized from two AcrPNP ligands differing in their P-substituents (iPr vs Ph), in conjunction with various Ir(I)-olefin precursors, through different sequences of reactions that include intramolecular C H activations and additions of H 2 and NaBEt 3 H. The new iridium complexes, with their observed structures and reactivities, reflect the unique properties of the acridine-based PNP ligands, i.e., their inherent structural flexibility and ability to support both metal-centered reactivity (C H and H H oxidative addition) and ligand-centered reactivity (hydride- and H 2 -induced dearomatization). [ABSTRACT FROM AUTHOR]