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Herein, we report an efficient strategy towards the synthesis of amino acid substituted isoquinoline derivatives via reaction of unprotected amino acid/amino acid ester/amino acid based drugs with 2‐(2‐oxo‐2‐aryl/alkylethyl)benzonitrile under metal‐free conditions. The developed protocol is highly simple and shows functional group tolerance to provide corresponding novel amino acid substituted isoquinolines in aqueous medium. The applicability of the reaction is an easier modification of well‐known drugs and successfully extended to gram‐scale synthesis. [ABSTRACT FROM AUTHOR]

An efficient boron Lewis acids mediated sulfonylation reaction has been successfully developed for the synthesis of C(sp3)‐sulfonylation isoindolinones, utilizing various γ‐hydroxy lactams and sulfonic nucleophile. The prominent features of the present strategy include wide substrate scope, excellent group tolerability, high atom economy, and moderate to good yields (up to 97 % yield). [ABSTRACT FROM AUTHOR]

Conventional oxidation processes for alkyl aromatics to ketones employ oxidants that tend to generate harmful byproducts and cause severe equipment corrosion, ultimately creating critical environmental problems. Thus, in this study, a practical, efficient, and green method was developed for the synthesis of aromatic ketones by applying a bis(2-butoxyethyl) ether/O2 system under external catalyst-, additive-, and base-free conditions. This O2-mediated oxidation system can tolerate various functional groups and is suitable for large-scale synthesis. Diverse target ketones were prepared under clean conditions in moderate-to-high yields. The late-stage functionalization of drug derivatives with the corresponding ketones and one-pot sequential chemical conversions to ketone downstream products further broaden the application prospects of this approach. [ABSTRACT FROM AUTHOR]

Trifunctional electrocatalysts, an exciting class of materials that can simultaneously catalyze hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR), can significantly enhance the performance and economic viability of electrochemical energy storage and conversion technologies such as water‐splitting electrolyzers, metal‐air batteries, fuel cells and their integrated devices. Such multifunctional electrocatalysts encompass multiple active sites that can simultaneously catalyze two or more different electrochemical reactions and are feasible routes for addressing global energy and environmental challenges. This review accounts for nanocarbons‐based trifunctional electrocatalysts reported for electrolyzers, metal‐air batteries and integrated electrolyzer‐battery systems, providing a practical perspective. Metal‐free and hybrid (hybrids of nanocarbons and transition metals/compounds) trifunctional electrocatalysts are covered. Given the growing importance of green technologies, we discuss biomass‐derived carbon‐based trifunctional electrocatalysts separately. The collective information provided in the review could help researchers derive more effective and durable trifunctional electrocatalysts suitable for commercial use. [ABSTRACT FROM AUTHOR]

Synthesis of functionalized 1,3‐indandiones containing‐cyclopentenones and ‐benzotropones has been achieved by the reaction of 1,5‐diphenylpenta‐1,4‐diyn‐3‐ones with 1,3‐indandiones, bindone respectively. The developed method involves Michael‐anti‐Michael addition cascade reactions under transition‐metal‐free conditions. This is the first report to synthesise diverse benzotropone fused with 1,3‐indandiones under transition metal‐free conditions from bindone. [ABSTRACT FROM AUTHOR]

We disclose herein a triflic acid and silane‐promoted reductive deoxygenative transformation of ketoacid/esters for the divergent synthesis of different‐sized lactones, which hold substantial significance in pharmaceutical and natural product chemistry. Owing to the simple reaction conditions and setup, this protocol features broad substrate generality, scalability, and good functional group tolerance, including late‐stage functionalization of pharmaceutical compounds and natural products. The control experiments and detailed NMR study provide insight into the reaction mechanism. [ABSTRACT FROM AUTHOR]

A metal‐free hypervalent iodine‐mediated C3‐trifluoropropionyloxylation of N‐substituted indoles was developed. (Bis‐trifluoropropanoate)iodobenzene was used as both the oxidant and fluorine source. The reaction was sensitive to the N‐protecting groups of the indoles. N‐acylated indoles provided 3‐trifluoropropionyloxylated indoles, while 3‐trifluoropropionyloxylated oxindoles were generated from indoles bearing N‐alkyl groups. [ABSTRACT FROM AUTHOR]

Despite the current research aims at replacing expensive metals like Platinum with non-noble metals for producing hydrogen via hydrogen evolution reaction (HER), practical challenges like oxidation continue to be a significant concern. Our study aims at providing the metal-free alternative to such noble Pt-based catalysts. Taking care of the fact that the defects are inevitable during the material's growth process, we propose thermodynamically and thermally stable two-dimensional (2D) Polyaramid (2DPA) with possible intrinsic point defects as HER active materials with overpotentials comparable to that of Pt catalysts using density functional theory (DFT). Creating single carbon (V C), single nitrogen (V N), and single oxygen (V O) vacancies helps reducing its wide band gap upon creation of several defect states, thereby improving conductivity. V O -2DPA exhibits lowest Δ G H * value of −0.04 eV which is closest to thermoneutrality condition, i.e., Δ G H * ≈ 0 while V N -2DPA is not found suitable for HER. The calculated low formation energies for generating point-vacancies under defect-poor growth conditions and the minimal bond length fluctuations within, serve as strong validation for the feasibility of their synthesis. Furthermore, underlying reaction mechanisms are also investigated for the HER process favouring the Heyrovsky reaction path over Tafel as the former requires lesser activation energy: 0.53 eV v. 0.86 eV for V C -2DPA and 0.34 eV v. 1.01 eV for V O -2DPA. [Display omitted] • A metal-free 2D Polyaramid (2DPA) with common point-vacancies is utilized as an electrocatalyst for HER using DFT. • Creation of point-vacancies introduces mid-gap states, causing band gap reduction. • Defective structures exhibit low defect formation energies and high room temperature structural stability. • C-defective and O-defective 2DPA exhibit platinum comparable overpotentials, boosting the HER activity. • Low energy barriers of 0.53 eV for C-defective and 0.34 eV for O-defective 2DPA suggest quick H 2 desorption. [ABSTRACT FROM AUTHOR]

Low‐energy light, endowing with excellent characteristics of lower energy, fewer side reactions, more abundance in solar light. The scenario has been developed for the fabrication of indenone through a low‐energy green light driven radical annulation reaction between α‐keto acids and internal alkynes using Rhodamine 6G as photocatalyst. Various kinds of substrates are suitable for this methodology, affording the corresponding indenones in a greener and efficient manner. [ABSTRACT FROM AUTHOR]

In this study, a difluorocarbene‐promoted O−O bond activation of peroxy acids is developed through the insertion of difluorocarbene into O−H bond. This activation strategy in synergy with O−B coordination with boronic acids/ester greatly polarizes the O−O bond for in‐situ generation of carboxylium species that reacts with the nucleophilic part of boronic acids in a concerted way to produce carboxylic esters. Good efficiency and functional group tolerance are demonstrated. Application of this method to the functionalization of a boronic acid drug used as HSL enzyme inhibitor produces smoothly the ester derivative. This difluorocarbene‐mediated O−O bond activation strategy is conceptually different from traditional radical type methods, and is also complementary to conventional esterification methods with a distinct retro‐synthetic disconnection. [ABSTRACT FROM AUTHOR]

The metal-free direct oxidative cross-dehydrogenative C–H bond amination of imidazopyridines with pyrazole in water as solvent has been developed under K2 S2 O8-promoted mild conditions. This strategy was applied to variable imidazoheterocycles to give amination products in moderate to good yields. The described protocol also offers scale-up synthesis for the construction of C–N bonds, which makes it suitable for the synthesis of biologically active compounds and pharmaceuticals. [ABSTRACT FROM AUTHOR]

ABSTRACT Imidazole moiety when fused with other heterocyclic system form numerous compounds with different types of pharmacological and biological activities. In this review, we discussed a comprehensive analysis of the synthetic methodologies and reaction mechanisms for imidazo‐fused heterocyclic molecules. These molecules represent a crucial class of compounds due to their significant applications and versatile chemical reactivity. This article meticulously examined various synthetic routes for the construction of imidazo‐fused heterocycles, ranging from traditional methods to modern approaches such as microwave‐assisted reactions, NPs‐catalyzed reactions, light‐mediated synthesis, electrochemical reactions, and transition metal‐free synthesis routes. By consolidating the current knowledge and highlighting future directions, this review aims to serve as a treasure for research community in the fields of organic chemistry, medicinal chemistry, and material science. [ABSTRACT FROM AUTHOR]

Visible‐light active heterogeneous organophotocatalysts have recently gained considerable interest in organic synthetic community. Ordered mesoporous polymers (OMPs) are highly promising as heterogeneous alternative to traditional precious metal/organic dyes‐based photocatalysts. Herein, we report the preparation of a benzothiadiazole functionalized OMPs (BT‐MPs) through a "bottom‐up" strategy. High ordered periodic porosity, large surface area, excellent stability and rational energy‐band structures guarantee the high catalytic activity of BT‐MPs. As a result, at least six conversions, e. g., the [3+2] cycloaddition of phenols with olefins, the selective oxidation of sulfides, the C‐3 thiocyanation of indole and the aminothiocyanation of β‐keto ester, could be promoted smoothly by BT‐MPs. In addition, BT‐MPs was readily recovered with well maintaining its photocatalytic activity and could be reused for at least eight times. This study highlights the potential of exploiting photoactive OMPs as recyclable, robust and metal‐free heterogeneous photocatalysts. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A visible‐light‐induced photoredox‐catalyzed regioselective and stereoselective C(sp2)–H amination of enamides with bench‐stable and easily accessible N‐aminopyridium salts is developed, affording synthetically and biologically prominent vicinal 1,2‐diamine scaffolds with broad substrate scope and excellent functional group compatibility. The transformation proceeded through a radical pathway involving the Giese addition of the relatively electrophilic N‐centered sulfonamidyl radical species to nucleophilic β‐olefinic position of enamides followed by the ensuing single electron oxidation and β‐H elimination, delivering geometrically‐defined Z‐configured β‐sulfonamidylated enamides. The operational simplicity, environmental friendliness and cost efficiency of this methodology allowed it to pave a new avenue to enrich the arsenal of synthetically crucial functionalized enamides and their related derivatives. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Allenes, served as highly sought‐after building blocks, are an indispensable component of synthetic chemistry. Their utility in modulating the chemical, physical, and pharmaceutical properties of organic compounds make allenes a desirable choice in various applications. Here, we report a facile method for the atom‐economical synthesis of propargyl allenylamines via an underdeveloped [2,3]‐sigmatropic rearrangement. Our strategy employs easily accessible propargylamines as starting materials, which are first converted into propargyl ammonium salts, followed by a base‐promoted [2,3]‐sigmatropic rearrangement. This one‐pot, two‐step reaction proceeds in the absence of transition metals, displays a very broad scope, and does not require the introduction of the electron‐withdrawing group into the starting materials. [ABSTRACT FROM AUTHOR]

Visible‐light induced, photoredox catalysis has opened a wide range in the transformation of organic compounds in recent times. In synthetic organic chemistry HAT (hydrogen atom transfer) and SET (single electron transfer) mechanisms are a very noteworthy routes that has opened a window in favor of C−C single bond formations. Usually, a major role of unsaturated hydrocarbons is to participate in carbon‐carbon bond formation as they carry reactive π‐bond. Under visible‐light, metal‐free cross‐coupling reactions are particularly favorable because of their atom economy, increased efficiency, and environmentally friendly procedures that result in the construction of C−C bonds. The review emphasizes the latest advancements of visible‐light mediated, cross‐coupling reactions of unsaturated hydrocarbons in metal‐free conditions for constructing carbon‐carbon single bonds. [ABSTRACT FROM AUTHOR]

A viable tactic to effectively address the climate crisis is the production of renewable fuels via photocatalytic reactions using solar energy and available resources like carbon dioxide (CO2) and water. Organic polymer material-based photocatalytic materials are thought to be one way to convert solar energy into valuable chemicals and other solar fuels. The use of porous organic polymers (POPs) for CO2 fixation and capture and sequestration to produce beneficial compounds to reduce global warming is still receiving a lot of interest. Visible light-responsive organic photopolymers that are functionally designed and include a large number of heteroatoms and an extended π-conjugation allow for the generation of photogenerated charge carriers, improved absorption of visible light, increased charge separation, and decreased charge recombination during photocatalysis. Due to their rigid structure, high surface area, flexible pore size, permanent porosity, and adaptability of the backbone for the intended purpose, POPs have drawn more and more attention. These qualities have been shown to be highly advantageous for numerous sustainable applications. POPs may be broadly categorized as crystalline or amorphous according to how much long-range order they possess. In terms of performance, conducting POPs outperform inorganic semiconductors and typical organic dyes. They are light-harvesting materials with remarkable optical characteristics, photostability, cheap cost, and low cytotoxicity. Through cocatalyst loading and morphological tweaking, this review presents optimization options for POPs preparation techniques. We provide an analysis of the ways in which the preparative techniques will affect the materials' physicochemical characteristics and, consequently, their catalytic activity. An inventory of experimental methods is provided for characterizing POPs' optical, morphological, electrochemical, and catalytic characteristics. The focus of this review is to thoroughly investigate the photochemistry of these polymeric organic photocatalysts with an emphasis on understanding the processes of internal charge generation and transport within POPs. The review covers several types of amorphous POP materials, including those based on conjugated microporous polymers (CMPs), inherent microporosity polymers, hyper-crosslinked polymers, and porous aromatic frameworks. Additionally, common synthetic approaches for these materials are briefly discussed. [ABSTRACT FROM AUTHOR]

Photoinduced the direct oxidation of benzyl C(sp3)−H bonds provides an attractive strategy for producing high‐value chemicals or intermediates. Unlike the conventional approaches that typically require transition‐metal catalysts, semiconductors, and organic photosensitizers as the photocatalysts, herein we report a bromine salt‐promoted photoinduced aerobic oxidation protocol for methylarenes. By applying NH4Br as both the bromine radical source and hydrogen atom transfer agent, photoinduced oxidation of methylarenes to the corresponding carboxylic products exhibits high conversion and selectivity. Furthermore, control experiments confirm that reactive oxygen species are proved to be essential for the success of this transformation. This strategy provides a metal‐/strong oxidant‐/photocatalyst‐free paradigm for the direct deep oxidation of methylarenes. [ABSTRACT FROM AUTHOR]

In this study, we explored the reactivity of meta‐trifluoromethanesulfonate (OTf) substituted diaryliodonium salts under alkaline conditions. Two distinct pathways with direct arylation of pyrrole derivatives and Diels‐Alder cycloaddition via aryne intermediates, have been found upon the relative alkalinity strength of potassium carbonates or hydroxides. This approach offers a straightforward and efficient route to synthesize heterocyclic aromatics under mild reaction conditions with tolerance of various functional groups. [ABSTRACT FROM AUTHOR]

At room temperature, the conversion of greenhouse gases into valuable chemicals using metal-free catalysts for dry reforming of methane (DRM) is quite promising and challenging. Herein, we developed a novel covalent organic porous polymer (TPE-COP) with rapid charge separation of the electron--hole pairs for DRM driven by visible light at room temperature, which can efficiently generate syngas (CO and H2). Both electron donor (tris(4-aminophenyl)amine, TAPA) and acceptor (4,40,400,4000-((1 E,10E,100E, 1000E)-(ethene-1,1,2,2-tetrayltetrakis (benzene- 4,1-diyl))tetrakis (ethene-2,1-diyl))tetrakis (1-(4-formylbenzyl)quinolin-1-ium), TPE-CHO) were existed in TPE-COP, in which the push--pull effect between them promoted the separation of photogenerated electron--hole, thus greatly improving the photocatalytic activity. Density functional theory (DFT) simulation results show that TPE-COP can form charge-separating species under light irradiation, leading to electrons accumulation in TPE-CHO unit and holes in TAPA, and thus efficiently initiating DRM. After 20 h illumination, the photocatalytic results show that the yields reach 1123.6 and 30.8 mmol g1 for CO and H2, respectively, which are significantly higher than those of TPE-CHO small molecules. This excellent result is mainly due to the increase of specific surface area, the enhancement of light absorption capacity, and the improvement of photoelectron-generating efficiency after the formation of COP. Overall, this work contributes to understanding the advantages of COP materials for photocatalysis and fundamentally pushes metal-free catalysts into the door of DRM field. [ABSTRACT FROM AUTHOR]

At room temperature, the conversion of greenhouse gases into valuable chemicals using metal-free catalysts for dry reforming of methane (DRM) is quite promising and challenging. Herein, we developed a novel covalent organic porous polymer (TPE-COP) with rapid charge separation of the electron–hole pairs for DRM driven by visible light at room temperature, which can efficiently generate syngas (CO and H2). Both electron donor (tris(4-aminophenyl)amine, TAPA) and acceptor (4,4′,4″,4‴-((1 E,1′E,1″E, 1‴E)-(ethene-1,1,2,2-tetrayltetrakis (benzene-4,1-diyl))tetrakis (ethene-2,1-diyl))tetrakis (1-(4-formylbenzyl)quinolin-1-ium), TPE-CHO) were existed in TPE-COP, in which the push–pull effect between them promoted the separation of photogenerated electron–hole, thus greatly improving the photocatalytic activity. Density functional theory (DFT) simulation results show that TPE-COP can form charge-separating species under light irradiation, leading to electrons accumulation in TPE-CHO unit and holes in TAPA, and thus efficiently initiating DRM. After 20 h illumination, the photocatalytic results show that the yields reach 1123.6 and 30.8 μmol g−1 for CO and H2, respectively, which are significantly higher than those of TPE-CHO small molecules. This excellent result is mainly due to the increase of specific surface area, the enhancement of light absorption capacity, and the improvement of photoelectron-generating efficiency after the formation of COP. Overall, this work contributes to understanding the advantages of COP materials for photocatalysis and fundamentally pushes metal-free catalysts into the door of DRM field.

Two types of poly-porphyrin-based heterogeneous photocatalysts including insoluble polymer and water-soluble nanoparticles exhibited excellent photocatalytic activity in visible-light-induced dehydrogenation in water. The extremely low catalyst loading (0.01 ​mol%) of water-soluble nanoparticles provided so far the highest turnover frequency (TOF) value (333 h-1) for such transformation among reported records.

A metal-free, efficient and easy-to-hand protocol for the synthesis of 2-perfluoroalkylquinazolins has been achieved by Eosin B catalyzed radical cascade arylation/cyclization reaction of fluorinated imidoyl isothiocyanates with aryldiazonium Salts. A variety of highly functionalized quinozaline derivatives bearing pharmaceutically important thiol and fluoroalkyl groups were efficiently assembled with broad substrate scope and good functional group tolerance. A series of mechanism experiments indicate that this reaction undergoes a radical cascade arylation/cyclization pathway.

The visible light‐induced decarboxylative cascade reaction of fluoroalkyl carboxylic acids has been achieved for the efficient synthesis of fluorinated compounds. However, most of the transformations rely on noble iridium metal complex. Herein, a visible light‐induced metal‐free decarboxylative cascade reaction of fluoroalkyl carboxylic acids has been realized. This protocol features simple operation, transition metal free, and good functional group tolerance. [ABSTRACT FROM AUTHOR]

Taking iodine-peroxide and diphenyldiselelen ether as raw materials, dimethyl sulfoxide as solvent, ammonium iodide and potassium tert-butoxide as catalysts, C Se bond coupling was formed at room temperature, and 11 selenium aryl peroxides were synthesized. By using HNMR spectroscopy, CNMR spectroscopy and mass spectrometry, the products were characterized and analyzed separately. Through a series of control experiments, the reaction was determined to be ionic and the corresponding reaction mechanism was inferred. The results show that 11 selenium aryl peroxides are all yellow liquid. The yield is 68%~85%. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are a promising class of organic polymers with the merits of robust framework, ultrahigh porosity, and molecularly precise backbones, which reveals great potential for solar‐to‐chemical energy conversion in the context of mitigating energy and environmental crises. However, the photochemical activities of individual COFs are not as robust as desired, primarily due to their limited light absorption, insufficient dissociation of photogenerated excitons and readily recombined photogenerated carriers. Recently, COFs‐based metal‐free heterojunctions with synergistic effects provide a feasible route to boost the photocatalytic activity of COFs in more environmentally friendly and cost‐competitive manners. Herein, it is first systematically overview the advances in COFs‐based metal‐free heterojunctions from heterojunction types, heterointerfaces interactions, and primary design mechanisms. Then, typical COFs‐based metal‐free heterojunction photocatalysts (e.g., g‐C3N4‐COFs, carbon materials‐COFs, polymer semiconductor‐COFs, COFs‐COFs heterojunction) are summarized. Finally, the challenges and long‐term outlooks for future advances of COFs‐based metal‐free heterojunction photocatalysts are offered from the terms of photocatalytic efficiency, yield, stability, cost and reaction mechanisms, as well as the standardized evaluation method of activities. It is anticipated that this review can deliver new insights into the fundamental and engineering of COFs‐based metal‐free heterojunctions for solar‐to‐chemical energy conversion, and further accelerate the development of this area. [ABSTRACT FROM AUTHOR]

A new variant of Fisher indole synthesis involving Bronsted acid-catalyzed hydrohydrazination of unactivated terminal and internal acetylenes with arylhydrazines is reported. The use of polyphosphoric acid alone either as the reaction medium or in the presence of a co-solvent appears to provide the required balance for activating the C–C triple bond towards the nucleophilic attack of the hydrazine moiety without unrepairable reactivity loss of the latter due to competing amino group protonation. Additionally, the formal hydration of acetylenes to the corresponding ketones occurs under the same conditions, making it an alternative approach for generating carbonyl groups from alkynes. [ABSTRACT FROM AUTHOR]

A variety of 2-substituted 3-selanyl-chromenones are readily prepared through a cascade selanylation/cyclization of alkynyl aryl ketones with sulfonoselenoates. This transformation is performed under metal-free conditions and does not require an additional oxidant. It also has the advantage of broad functional group tolerance and scalability. [ABSTRACT FROM AUTHOR]

A BF3 ·OEt2-promoted facile synthesis of cyclic amidines (2-amino-1-pyrrolines) has been developed via the (3+2)-cycloaddition of cyanamides with donor-acceptor cyclopropanes (DACs). In addition to this, the protocol has been successfully extended to construct a dimerized amidine derivative and gram-scale synthesis with great efficiency. [ABSTRACT FROM AUTHOR]

Using organic dyes as photocatalysts is an innovative approach to photocatalytic organic transformations. These dyes offer advantages such as widespread availability, adaptable absorption properties, and diverse chemical structures. Recent progress has led to the development of organic photocatalysts that can utilize visible light to modify chemically inert C−H bonds. These catalysts are sustainable, selective, and versatile, enabling mild reactions, late‐stage functionalization, and various transformations in line with green chemistry principles. As catalysts in photoredox chemistry, they contribute to the development of efficient and environmentally friendly synthetic pathways. Acridinium‐based organic photocatalysts have proved valuable in late‐stage C−H functionalization, enabling transformative reactions under mild conditions. This review emphasizes their innovative features, such as organic frameworks, efficient light absorption properties, and their applications in modifying complex molecules. It provides an overview of recent advancements in the use of acridinium‐based organic photocatalysts for late‐stage C−H bond functionalization without the need for transition metals, showcasing their potential to expedite the development of new molecules and igniting excitement about the prospects of this research in the field. [ABSTRACT FROM AUTHOR]

An efficient and environmental protocol for the synthesis of 3‐aryl‐2H‐benzo[b][1,4]oxazin‐2‐ones under mild benign conditions has been developed. This facile one‐pot approach to 3‐aryl‐2H‐benzo[b][1,4]oxazin‐2‐ones from commercially available benzoxazoles and α‐keto acids which only promoted by DIPEA. The protocol exhibits a wide range of applicability in terms of benzoxazoles and α‐keto acids. Notably, the 2‐aryl benzothiazoles can be produced under the similar reaction conditions. [ABSTRACT FROM AUTHOR]

Crystalline and soluble 1D linear conjugated polymers (LCPs) have garnered considerable interest as cost‐effective and efficient metal‐free electrocatalysts for the oxygen reduction reaction (ORR) due to their high exposure of catalytic sites and ease of processing. However, difficulties remain in achieving excellent ORR performance for 1D LCPs by conventional molecular design. Herein, it is demonstrated the utilization of quinoidal units as a promising strategy to develop 1D LCPs for ORR. The incorporation of quinoidal unit not only results in polymers with strong inter‐ and intra‐molecular interactions and low‐lying LUMO (lowest unoccupied molecular orbital) energy levels, but also provides polymers with good crystallinity and commendable charge carrier mobilities. The electronic properties of these polymers are fine‐tuned through the introduction of additional heteroatoms and/or substituents in the monomers and comonomers to understand and optimize their ORR catalytic activity. Evaluation of their catalytic performances reveals a remarkable half‐wave potential and limiting current density of up to 0.74 V (vs reversible hydrogen electrod) and 7.50 mA cm−2, respectively. Notably, these performances are achieved without the addition of carbon nanomaterials as support. This study offers a new insight into the design of highly efficient metal‐free organic electrocatalysts. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A novel and eco‐friendly electrochemical activation of trifluoromethyl thianthrenium triflate (TT–CF3+OTf−) for trifluoromethylation of imidazole‐fused heteroaromatic compounds was established. This method involves the direct electrolysis of TT–CF3+OTf− without the requirement of external oxidants or catalysts, aligning with the principles of green chemistry. A wide range of imidazole‐fused heteroaromatic compounds including imidazo[1,2‐a]pyridines and benzo[d]imidazo[2,1‐b]thiazoles have been successfully trifluoromethylated using this technique, exhibiting excellent compatibility with various functional groups and a broad substrate scope. Moreover, the method's applicability for one‐pot sequential reactions enables the reduction of waste and resource consumption by eliminating the need for intermediate purification steps. [ABSTRACT FROM AUTHOR]

The environmentally benign synthesis of indoline boronic esters, especially through a way of arylboration to alkenes, remains a challenge due to the use of transition metals or high-temperature conditions. We described a photoinduced metal-free arylboration of unactivated alkenes for the synthesis of indoline boronic esters and 1,2,3,4-tetrahydroquinoline boronic ester in good yields. This approach showed good compatibility and great efficiency for a range of allylphenylamines as well as alkylamine. Remarkably, this transformation also suggested that the base is not necessary for photosensitizer-free diboron reagent mediated mild generation of aryl radical. Furthermore, compared to previously reported methods, this approach is mild and environmentally benign. [ABSTRACT FROM AUTHOR]

We describe herein a method for transition‐metal‐free (hetero)arylsulfonylation of 1‐iodopyrrolo[1,2‐a]quinoxalines with sodium arylsulfinates. The corresponding aryl iodides were in situ prepared from eletrophilic iodination of C1−H bonds in pyrrolo[1,2‐a]quinoxalines with N‐iodosuccinimide. The ensuing sulfonylation only required DMSO as solvent and completed after 15 min. Many arylsulfinates bearing chloro, bromo, methylsufonyl, acetamide, and nitro groups were competent substrates. Heteroarylsulfonylation of pyrrolo[1,2‐a]quinoxalines were also feasible. [ABSTRACT FROM AUTHOR]

A metal‐free three‐component reaction for the direct synthesis of α‐sulfonamide phosphonates involving sulfonamide derivatives, benzaldehyde derivatives, and diethyl phosphite, has been achieved with high yields using ethanol as a green solvent. This efficient method reduces reaction time and minimizes the use of excess reagents. Hitherto, no reports have been found in the literature for the direct synthesis of α‐sulfonamide phosphonates from the readily available aldehydes, diethyl phosphite, and sulfonamides, emphasizing the novelty and significance of this work. [ABSTRACT FROM AUTHOR]

Denitrogenative organic transformations and related reactions are a class of significant approaches for carrying out unusual C−C/C‐heteroatom (C−O, C−N, C−S) bond‐forming reactions that are usually promoted by Ru, Ir, Pd, Ni, and Cu metal catalysts. In this trait, numerous methods were adopted to synthesize several pharmaceutically valuable N‐ and O‐containing heteroaromatics using 1,2,3‐benzotriazin‐4(3H)‐one as an electrophilic coupling partner. This review involves the recent achievements related to the metal/organo‐catalyzed thermal and visible‐light mediated denitrogenative approaches with 1,2,3‐benzotriazin‐4(3H)‐ones towards the synthesis of imperative N‐heteroaromatic compounds. In addition, metal and oxidant‐free ortho‐functionalization of benzotriazinones by using suitable nucleophilic partners have been discussed. In particular, the most novel methods employing Ni and Pd metal catalysts that have emerged are exhibited. Specific attention has been paid to offering the detailed mechanistic pathway to explain the role of metal catalysts and the mechanism in the absence of metal catalysts in the denitrogenative reactions under a thermal/visible light medium. [ABSTRACT FROM AUTHOR]

Here we introduce a metal‐free, catalytic and enantioselective strategy from α,β‐unsaturated 2‐acyl imidazoles to the chiral phosphorous 2‐acyl imidazoles. Interestingly, this methodology was catalyzed by the classical and commercial oxazaborolidine under mild conditions. This strategy features a wide range of substrates scope with good yields and excellent enantioselectivities. The possible mechanism further suggests the key of this reaction through the cleavage of diarylphosphine oxides using Frustrated Lewis Pairs theory. [ABSTRACT FROM AUTHOR]

This article proposes a milder approach for C(sp2=−H functionalization of 2,2‐disubstituted cyclopentene‐1,3‐dione via formal 1° amination utilizing water as a solvent. In addition, this approach also offers C(sp2)−O, C(sp2)−I bond formation for the first time using sodium azide. The said highly scalable transformation does not require any prefunctionalization of the starting material. Moreover, this methodology is metal free, requires no ligand and all these reactions are carried out in an open‐air atmosphere with broad substrate scope. We have also explored a novel BF3.OEt2 mediated dehalogenation using mild reaction conditions. [ABSTRACT FROM AUTHOR]

A straightforward and efficient methodology has been developed for the synthesis of 3-cyano-2-pyridones via the C–C and C–N bond formation processes. A total of 51 diverse 3-cyano-2-pyridone derivatives were obtained in moderate to excellent yields. This reaction featured advantages such as a metal-free process, wide functional group tolerance, simple operation, and mild conditions. A plausible mechanism for the reaction was proposed. 3-cyano-2-pyridones as ricinine analogues for insecticidal properties were evaluated, and the compound 3ci (LC50 = 2.206 mg/mL) showed the best insecticidal property. [ABSTRACT FROM AUTHOR]

Regio‐ and chemo‐selective functionalization of electron deficient azaarenes often required their transformations to corresponding N‐oxides and subsequent removal of oxygen after functionalization to get back the desired substituted azaarenes. An efficient metal‐free visible‐light photo‐redox catalytic deoxygenation of N‐oxides of azaheterocyclic compounds has been developed using acridinium based organo‐photocatalyst in blue LED light. High efficiency and mildness of this methodology has been demonstrated through higher deoxygenation yield of wide variety of azaheterocyclic N‐oxides with reactive functional groups. Robustness of the photocatalytic reduction has been demonstrated through easy scaling‐up of the reaction to gram level without much change in the reaction yield. [ABSTRACT FROM AUTHOR]

This article discusses the metal-free synthesis of trifluoromethyl carbinol-containing imidazo[1,2-a]pyridines through dehydrative coupling. Trifluoromethyl-containing compounds are important in various fields due to their biological activity and stability. Imidazo[1,2-a]pyridines are commonly found in pharmaceuticals, and the construction of CF3-containing imidazo[1,2-a]pyridines is valuable for drug discovery. The use of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as a medium for organic synthesis has been explored, and it has been found to promote the hydroxy-trifluoromethylation of imidazo[1,2-a]pyridines with trifluoroacetaldehyde. The optimized reaction conditions using HFIP as a solvent resulted in good yields of the desired products. The substrate scope of this process was also investigated, demonstrating its generality and practicality. This article describes a novel approach for the synthesis of trifluoromethyl carbinol-containing imidazo[1,2-a]pyridines using imidazo[1,2-a]pyridines and trifluoroacetaldehyde via a dehydrative cross-coupling process. The reaction was promoted by HFIP and exhibited wide substrate generality, excellent functional group tolerance, and mild reaction conditions. [Extracted from the article]

A novel metal-free synthesis of 3-substituted isocoumarins through a sequential O-acylation/Wittig reaction has been established. The readily accessible (2-carboxybenzyl)-triphenylphosphonium bromide and diverse chlorides produced various 1H-isochromen-1-one in the presence of triethylamine, employing sequential O-acylation and an intramolecular Wittig reaction of acid anhydride. Reactions using these facile conditions have exhibited high functional group tolerance and excellent yields (up to 90%). Moreover, the fluorescence properties of isocoumarin derivatives were evaluated at the theoretical and experimental levels to determine their potential application in fluorescent materials. These derivatives have good photoluminescence in THF with a large Stokes shift and an absolute fluorescence quantum yield of up to 14%. [ABSTRACT FROM AUTHOR]

The hypervalent iodine mediated, silica gel promoted synthesis of 2‐aminobenzazoles and 2‐aminobenzothiazole derivatives under metal‐free mild conditions within short time (30 min) has been developed. Under this process, PhI(COOCF3)2 (PIFA) or PhI(COOCH3)2 (PIDA) acts as an oxidant and radical initiator direct activated the ortho‐C−H bond of substrate, silica gel as weakly lewis acid effectively increased the reactivity of the reaction system. This method is compatible with various of arylurea and arylthiourea substrates, which is green, efficient, simple to operate and suitable for practical application. [ABSTRACT FROM AUTHOR]

Easy operation, readily accessible starting materials, and direct synthesis of iminotetrazoles via metal‐free aerobic oxidation were achieved in one‐pot Ugi‐azide multicomponent reactions. A study of the reactivity of 2‐hydroxybenzaldehyde (Salicylaldehyde) as single reactant replacement (SSR) in classical Ugi reaction has been carried out showing an outcome that differs by simply varying the ortho‐substituents of the benzaldehyde moiety. In doing so, various substituted imino tetrazole products could be obtained directly in one step by simple execution without oxidation step in good yields. Characterization of these new iminotetrazole products was confirmed by X‐ray analysis. [ABSTRACT FROM AUTHOR]

The synthesis of thioether derivatives has been explored widely due to the potential application of these derivatives in medicinal chemistry, pharmaceutical industry and material chemistry. Within this context, there has been an increasing demand for the environmentally benign construction of C–S bonds via C–H functionalization under metal-free conditions. In the present article, we highlight recent developments in metal-free sulfenylation that have occurred in the past three years. The synthesis of organosulfur compounds via a metal-free approach using a variety of sulfur sources, including thiophenols, disulfides, sulfonyl hydrazides, sulfonyl chlorides, elemental sulfur and sulfinates, is discussed. Non-conventional strategies, which refer to the development of thioether derivatives under visible light and electrochemically mediated conditions, are also discussed. The key advantages of the reviewed methodologies include broad substrate scope and high reaction yields under environmentally benign conditions. This comprehensive review will provide chemists with a synthetic tool that will facilitate further development in this field. [ABSTRACT FROM AUTHOR]

New nanocatalyst Lewis acid type promoted MCM-41@silyl-n-propyl modified 1,4-diazabicyclo[2.2.2]octane (MCM-41@SnPr-DABCO-H) as an effective, metal-free and heterogeneous reusable nanocatalyst was synthesized and characterized by FT-IR, SEM, TEM, EDS, XRD, TGA-DTG and Brunauer–Emmett–Teller (BET) techniques. This nanocatalyst was used in the clean synthesis of various CH-tetrazoles in moderate to high yields. The CH-tetrazoles were synthesized by the one-pot reaction of triethyl orthoformate, aniline derivatives and sodium azide in the presence of catalytic amount of nanocatalyst. CH-tetrazole structures were characterized and confirmed by FT-IR, 1H and 13C NMR spectroscopy techniques. [ABSTRACT FROM AUTHOR]