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Spontaneous ionization/breakup of water at the surface of aqueous droplets has been reported with evidence ranging from formation of hydrogen peroxide and hydroxyl radicals, indicated by ions at m/z 36 attributed to OH⋅‐H3O+ or (H2O‐OH2)+⋅ as well as oxidation products of radical scavengers in mass spectra of water droplets formed by pneumatic nebulization. Here, aqueous droplets are formed both by nanoelectrospray, which produces highly charged nanodrops with initial diameters ~100 nm, and a vibrating mesh nebulizer, which produces 2–20 μm droplets that are initially less highly charged. The lifetimes of these droplets range from 10s of μs to 560 ms and the surface‐to‐volume ratios span ~100‐fold range. No ions at m/z 36 are detected with pure water, nor are significant oxidation products for the two radical scavengers that were previously reported to be formed in high abundance. These and other results indicate that prior conclusions about spontaneous hydroxyl radical formation in unactivated water droplets are not supported by the evidence and that water appears to be stable at droplet surfaces over a wide range of droplet size, charge and lifetime. [ABSTRACT FROM AUTHOR]

Fluoroalkyl ketones are a class of structural motifs which are ubiquitous in bioactive molecules, and serve as synthons for diverse value‐added fluorine‐containing targets. The presence of fluorine significantly alters the lipophilicity and bioactivity of alkyl ketones as well as imposes additional challenges on the synthesis of fluoroalkyl ketones. Traditional methods for the synthesis of fluoroalkyl ketones heavily rely on multiple‐step manipulations which require stoichiometric reagents and suffer from low efficiency. Thus, the development of synthesizing fluoroalkyl ketones enabled by catalytic methods is highly valuable yet challenging. This Concept summarizes the recent renaissance in developing catalytic methods for the synthesis of fluoroalkyl ketones with diverse substitution patterns from different fluorine‐containing precursors. In addition, further efforts for catalytic method development are also discussed. [ABSTRACT FROM AUTHOR]

Herein, we report a vibration‐induced emission molecule, 9,14‐diphenyl‐dihydrodibenzo[a,c]phenazines (DPAC), compound‐catalyzed C−H difluoroalkylation of (hetero)arenes under visible light conditions. This method demonstrates the promising potential of vibration‐induced‐emission (VIE) molecules in photocatalysis and facilitates a metal‐free synthetic approach for difluoroalkyl (hetero)arenes with broad substrate scope and functional group tolerance. [ABSTRACT FROM AUTHOR]

Dithiocarbamates are common structural motifs in various bioactive compounds, attracting considerable attention due to their wide‐ranging applications in organic synthesis, material science, agrochemicals, and the pharmaceutical industry. Given the significant bioactivity and extensive applications of dithiocarbamates, the continuous pursuit of their efficient and diverse synthetic methods remains critical and urgent. Direct dithiocarbamation reactions can introduce −S−C(S)NR2 group directly into parent molecules, providing shorter, greener, and more practical pathways for the synthesis of organodithiocarbamates. This article offers a comprehensive overview of the latest advancements in direct dithiocarbamation reactions, categorizing them based on the different sources of the −S−C(S)NR2 group, with a particular emphasis on elucidating substrate scope and reaction mechanisms. Additionally, some synthetic limitations and applications of these methods are discussed. This review aims to provide the latest advancements in this field to both general readers and professional practitioners, inspiring innovative ideas for the synthesis of organosulfur compounds. [ABSTRACT FROM AUTHOR]

Sn‐based perovskites have emerged as one of the most promising environmentally‐friendly photovoltaic materials owing to their low toxicity and exceptional optoelectronic properties. Nonetheless, the low‐cost production and stable operation of Sn‐based perovskite solar cells (PSCs) are still largely limited by the costly hole transport materials and the under‐optimized interfaces between hole transport layer (HTL) and Sn perovskite layer. Here, we innovatively developed a chlorine radical chemical bridging (Cl‐RCB) strategy that enabled to remove the HTL and optimize the indium tin oxide (ITO)/perovskite heterointerface for constructing high‐performance Sn‐based PSCs with simplified structures. The key is to modify the commercially‐purchased ITO electrode with highly active chlorine radicals that could effectively mitigate the surface oxygen vacancies, alter the chemical constitutions, and favorably down‐shifted the work function of ITO surface to be close to the valence band of perovskites. As a result, the interfacial energy barrier has been largely reduced by 0.20 eV and the interfacial carrier dynamics have been optimized at the ITO/perovskite heterointerface. Encouragingly, the efficiency of HTL‐free Sn‐based PSCs has been enhanced from 6.79 % to 14.20 %, which is on par with the state‐of‐the‐art conventional HTL‐containing counterparts (normally >14 % efficiency) and representing the record performance for the Sn perovskite photovoltaics in the absence of HTL. Notably, the target device exhibited enhanced stability for up to 2000 h. The Cl‐RCB strategy is also versatile to be used in Pb‐based and mixed Sn−Pb HTL‐free PSCs, achieving efficiencies of 22.27 % and 21.13 %, respectively, all representing the advanced device performances for the carrier transport layer‐free PSCs with simplified device architectures. [ABSTRACT FROM AUTHOR]

The recent development of photoredox and energy transfer catalysis has led to a significant expansion of visible‐light‐driven chemical transformations. These methods have demonstrated exceptional efficiency in converting a wide range of substrates into radical intermediates and generating open‐shell catalytic species. However, the simplification of catalytic systems and the direct generation of highly reactive radical organocatalysts through direct visible‐light irradiation from stable precatalysts remains largely an unrealized goal. This challenge is mainly due to the limited availability of precatalysts that are responsive to visible light. Herein, we introduce a new class of bench‐stable dicationic disulfuranes, which release highly reactive thiyl radicals upon blue‐light excitation. Spectroscopic and computational studies reveal that this reactivity arises from a combination of structural features and intermolecular interactions. This family of molecules has been employed to catalyze radical cascades previously incompatible with photoredox conditions, enabling the efficient formation of 1,2‐dioxolanes and 1,3‐hydroxyketones in excellent yields and short reaction times. [ABSTRACT FROM AUTHOR]

Sulfation is a highly valuable pathological and physiological process, yet it is often underappreciated considering the rather difficult accessibility of organosulfates. O‐sulfonation (O−SO3), a conventional and still common way to make organosulfates, restricts its applicability to hydroxyl compounds and therein lies a major challenge of library construction. Here, we describe a benzylic C−H radical sulfation with persulfates via C−O bond formation. This strategy leverages modular control over the reactivity of persulfates and the stability of sulfate radicals by coutercations. K+/NH4+ stabilized sulfate radicals act as the oxidant to generate carbon‐centered radicals from substrates, and activation of persulfates by n‐NBu4+ provides O−O resource pool to facilitate C−OSO3− bond formation via a bimolecular homolytic substitution (SH2) process. [ABSTRACT FROM AUTHOR]

The rapid development of photo‐synergistic transition metal catalytic systems has provided a green paradigm to complement thermal transition metal catalytic methods. However, the most commonly used iridium or ruthenium complexes involve expensive in nature, in contrast to the abundant copper elements in the earth's crust, which are highly valued for their unique electronic structure and light‐absorbing properties. Recently, the application of copper and photocatalytic synergistic strategies in radical cyclization reactions has progressed considerably, leading to a renaissance in the synthesis of functional natural products, drugs and their analogues, but summary work addressing this aspect has not been reported. In this review, we briefly analyze the effect of ligand choice on copper complexes and some inorganic copper salts and even on light sources. We then summarize the copper and photocatalytic synergistic strategies in radical cyclization reactions and classify them into three categories, C, N and O radicals, according to the class of the central atom of the radical in each work, and in each category will be elaborated in turn from coordination cyclization via Cu catalysts, direct radical cyclization and other cyclization mode. For individual more complex reactions, the mechanisms are explored and briefly discussed. [ABSTRACT FROM AUTHOR]

Oxygen-assisted oxidative dehydrogenation of propane (O2-ODHP) to propylene is a promising route that complements the existing oil-based processes to bridge the gap between continuously increasing market demand and productivity of propylene. This reaction i) is free from thermodynamic constraint and ii) features minimized coke deposition of the catalyst. A major challenge of ODHP lies in the over-oxidation to undesired carbon oxides (COx). Transition metal oxides have been extensively explored in the past decades; however, they suffer from a low olefin selectivity. Most recently, hexagonal boron nitride (h-BN) emergesas a promising candidate for ODHP, which shows a unique high selectivity toward light olefins (C2-C3) and negligible COx formation. To interpret the origin of such unique catalytic performance, significant efforts have been put forth in identifying active sites and developing an in-depth understanding of reaction mechanisms through combined experimental and computational approaches. In general, boron-oxide species are identified as the active sites, and a surface-induced gas-phase reaction mechanism has been proposed, though detailed scenarios vary. These findings explain the Eley-Rideal kinetic behavior and unique high olefin selectivity of h-BN. The breakthrough in h-BN catalysts revitalizes the exploration of boron-oxide catalysts because of their identical kinetic behavior and similar active sites to h-BN catalysts. With the accumulated knowledge, continuous endeavor is devoted to developing advanced boron-containing materials for enhanced activity and durability. This review aims to summarize the recent advances in ODHP on boron-based catalysts, with particular emphases on catalytic performance, kinetic behavior, stability and leaching issues, identification of active sites, and site-dependent reaction mechanisms, as well as the development of advanced boron-based materials. With this review, we expect to not only provide an overview to keep abreast of the state-of-the-art boron-containing catalytic materials for ODHP, but also to identify key descriptors for designing efficient boron-based catalysts with low-temperature activity. TOC: [ABSTRACT FROM AUTHOR]

Fundamental understanding of initial evolutions of molecules in the universe is of great interest and importance. CH4 is one of the abundant simple molecules in the universe. Herein we report γ‐ray, high‐energy photons commonly existing in cosmic rays and unstable isotope decay, as an external energy to efficiently drives aqueous‐phase CH4 conversions to various products with the presence of oxygen at room temperature. Glycine also forms with an additional introduction of ammonia. Both CH4 conversions and product distributions are modified by solid granules, and a CH3COOH selectivity as high as 82 % is obtained when SiO2 is added. Our results point to γ‐ray driven aqueous‐phase CH4 conversions as a likely formation network of initial complex organic compounds in the universe and offer an alternative strategy for efficiently utilizing CH4 as the carbon source to produce value‐added products at mild conditions, a long‐standing challenging task in heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Organophosphorothioates are organic molecules containing sulfur and phosphorus, with significant biological activity and physicochemical properties, widely used in organic synthesis, medicinal chemistry, and the agrochemical industry. In particular, many phosphorothioates display a variety of biological activities, such as antifungal, antibacterial, anti‐parasite, anticancer, and so on. Traditionally, the synthesis of phosphorothioates has mainly relied on indirect methods involving the construction of S−P bond. In recent years, direct phosphorothiolation has gained attention as a reliable and rapid method for introducing the −S−P(O)(OR)2 group into parent molecules. This article reviews the latest advances in direct phosphorothiolation reactions, categorized based on the different sources of the −S−P(O)(OR)2 group. [ABSTRACT FROM AUTHOR]

[Display omitted] • The multifunctional additive HCCP-TMP was innovatively synthesized by combining the free radical trapping unit—hindered amine with the high-efficiency flame retardant element—HCCP. • HCCP-TMP significantly increased the upper limit of electrochemical window of the polyacrylate gel electrolyte, improving the compatibility with the nickel-rich high-voltage cathode NCM811. • The addition of HCCP-TMP significantly improved the cycling stability and rate performance of the polyacrylate gel electrolyte at high voltages. • 1 wt% HCCP-TMP can make the polyacrylate-based gel electrolyte non-flammable, and the equipped NCM811//graphite pouch battery will not exhibit fire behavior during thermal runaway, improving the fire safety of the battery. For high energy density lithium-ion batteries (LIBs) with nickel-rich ternary cathodes, the chemical degradation of electrolytes caused by free radical reactions and the hazards of thermal runaway have always been significant challenges. Inspired by the free radical scavenging of living organisms and multiphase synergistic flame retardant mechanism, we innovatively designed and prepared a multifunctional flame retardant HCCP-TMP that combines flame retardancy and free radical scavenging by combining hindered amine and cyclophosphazene. Only 1 wt% HCCP-TMP can make the polyacrylate-based gel polymer electrolyte (GPE) incombustible. Moreover, the equipped NCM811//Graphite pouch cells don't exhibit combustion behavior after thermal runaway and can resist mechanical abuse. Based on the above noncombustible GPE, the NCM811//Li battery exhibits capacity retention rate of 82.2 % after 100 cycles at a current density of 2 C and in the voltage range of 3.0–4.7 V, exhibiting excellent cyclability under high voltage. This simple molecular design simultaneously improves the fire safety and high voltage stability, demonstrating enormous application potential in the field of advanced LIBs with high safety and high energy density. [ABSTRACT FROM AUTHOR]

During the past decades, N‐heterocyclic carbene (NHC)‐catalyzed reactions have emerged as a versatile tool in synthetic chemistry. In particular, NHC‐catalyzed cross‐coupling reaction has been significantly developed in many respects, including new reaction development and mechanistic investigation. This concept article presents recent advances towards direct cross‐coupling reactions of aldehydes with alkyl halides enabled by NHC organocatalysis. [ABSTRACT FROM AUTHOR]

This concept paper aims to summarize recent research on the design and synthetic applications of metal‐organic frameworks (MOFs)‐based hydrogen atom transfer (HAT) catalysts. Functional MOFs have emerged as highly promising heterogeneous catalysts, leveraging their tunable, ordered structure and abundant active sites to enhance catalytic efficiency in various reactions. HAT, a versatile method for generating active open‐shell radical species through selective hydrogen abstraction, has been well explored in homogeneous photocatalysis. In contrast, heterogeneous HAT catalysis remains less developed, albeit their great potential in industry. This paper will provide a timely overview of the advancements in MOFs‐based HAT photocatalysis, classified according to catalytic centers including aromatic ketones, polyoxometalates, xanthene dyes, thiols, and alcohols, highlighting their design principles and practical applications in photocatalytic organic synthesis. [ABSTRACT FROM AUTHOR]

Conjugated molecules with multiple radical centers such as the iconic Chichibabin diradicaloid hold promise as building blocks in materials for quantum sensing and quantum information processing. However, it is a considerable challenge to design simple analogues of the Chichibabin hydrocarbon that are chemically inert, exhibit high diradical character and emit light at a distinct wavelength that may offer an optical readout of the spin state in functional ensembles. Here we describe the serendipitous discovery of the stable TTM‐TTM diradicaloid, which exhibits high diradical character, a striking sky‐blue color and near‐infrared (NIR) emission (in solution). This combination of properties is unique among related diradicaloids and is due to the presence of hydrogen and chlorine atoms in "just the right positions", allowing a perfectly planar, yet predominantly benzenoid bridge to connect the two sterically stabilized radical centers. In‐depth studies of the optical and magnetic properties suggest that this structural motif could become a mainstay building block of organic spin materials. [ABSTRACT FROM AUTHOR]

The increasing use of fluorine‐containing bioactive molecules necessitates efficient strategies for fluorinated group installation. Despite the impressive development of photoinduced radical fluoroalkylation as a powerful tool for introducing fluorine, the persistent issues, including the recyclability and reaction specificity of homogeneous photocatalysts, still leave great room for further advancement in a sustainable and general fashion. Herein, we report a conceptually different approach toward multiple types of fluoroalkylations by using recoverable and versatile graphitic carbon nitride (g‐CN) nanosheets as a heterogeneous photocatalyst. This photocatalytic system enables diverse intermolecular fluoroalkylations of alkenes with fluoroalkanesulfinates and intramolecular fluoroalkyl migrations of alkenyl triflates. Detailed characterizations and mechanism studies substantiate the stability of this organic semiconductor and the crucial role of photogenerated electron‐hole pairs. [ABSTRACT FROM AUTHOR]

Ozone (O3) pollution is usually linked to warm weather and strong solar radiation, making it uncommon in cold winters. However, an unusual occurrence of four high O3 episode days (with maximum hourly concentrations exceeding 100 ppbv and peaking at 121 ppbv) was recorded in January 2018 in Lanzhou city, China. During these episodes, the average daytime concentration of total non-methane volatile organic compounds (TVOCs) reached 153.4 ± 19.0 ppbv, with alkenes—largely emitted from the local petrochemical industry—comprising 82.3 ± 13.1 ppbv. Here we show a photochemical box model coupled with a Master Chemical Mechanism to elucidate the mechanisms behind this unusual wintertime O3 pollution. We find that the typically low temperatures (−1.7 ± 1.3 °C) and weak solar radiation (263.6 ± 60.7 W m-2) of those winter episode days had a minimal effect on the reactivity of VOCs with OH radicals. Instead, the ozonolysis of alkenes generated Criegee intermediates, which rapidly decomposed into substantial ROx radicals (OH, HO2, and RO2) without sunlight. This radical production led to the oxidation of VOCs, with alkene ozonolysis ultimately contributing to 89.6 ± 8.7% of the O3 formation during these episodes. This mechanism did not activate at night due to the depletion of O3 by the NO titration effect. Furthermore, the findings indicate that a reduction of alkenes by 28.6% or NOx by 27.7% in the early afternoon could significantly mitigate wintertime O3 pollution. Overall, this study unravels the unique mechanism of alkene-induced winter O3 pollution and offers a reference for winter O3 reduction strategies in the petrochemical industrial regions.

We report a user‐friendly approach for the decarboxylative formation of stereodefined and complex tri‐ and tetra‐substituted olefins from vinyl cyclic carbonates and amines as radical precursors. The protocol relies on easy photo‐initiated α‐amino‐radical formation followed by addition onto the double bond of the substrate resulting in a sequence involving carbonate ring‐opening, double bond relay, CO2 extrusion and finally O‐protonation. The developed protocol is efficient for both mismatched and matched polarity substrate combinations, and the scope of elaborate stereodefined olefins that can be forged including drug‐functionalized derivatives is wide, diverse and further extendable to other types of heterocyclic and radical precursors. Mechanistic control reactions show that the decarboxylation step is a key driving force towards product formation, with the initial radical addition under steric control. [ABSTRACT FROM AUTHOR]

Plasmodium falciparum is a fast-evolving parasite responsible for the fatal disease malaria, making it crucial to renew our therapeutic arsenal. Modulating the artemisinin's endoperoxide pharmacophore is a promising route to synthesizing new antimalarial derivatives. For the first step of our 20 mmol scale synthesis, catalyzed by manganese (III) acetylacetonate, we applied the conditions previously described in the literature to one of our low-yielding asymmetrically disubstituted alkenes, (2-methylallyl)benzene. Under conditions designed for alkyl derivatives, manganese (II) and (III) acetate catalyzed its peroxycyclization with methyl 3-oxobutanoate to a 1,2-dioxane ring in the presence of oxygen from air at room temperature with a 36% yield, while an oxygen atmosphere, as described in the literature, decreased the yield to 7%. Finally, under conditions designed for aryl derivatives, the yield was reduced to 30%, showing that methylallyl derivatives have an intermediate reactivity that needs further optimization to produce 1,2-dioxane ring by manganese catalyzation in good yields. This work characterizes the product obtained and discusses the most suitable reaction conditions. [ABSTRACT FROM AUTHOR]

Radical chemistry, a rapidly growing field in organic synthesis, offers numerous innovative approaches for the cleavage and construction of challenging chemical bonds. Recent findings have underscored the pivotal contributions of alkali metal ions in radical-driven reactions, where they play a crucial role in lowering the energy barriers required to initiate these processes and in stabilizing vital transient radical species. These properties contribute significantly to the advancement of next-generation synthetic techniques. This article offers a concise yet thorough examination of the roles alkali metal ions assume within radical chemistry, with a specific focus on their diverse modes of activation and the associated mechanistic contexts. Our objective is to encourage and expand their strategic use across various facets of organic synthesis, catalysis, and environmentally conscious green chemistry applications. [ABSTRACT FROM AUTHOR]

Molecules containing ether skeletons are widely present in drugs, natural products, functional materials, and life science. Direct C(sp3)−H bond ether functionalization is considered a powerful strategy for the construction of novel ether derivatives. Photo‐/electro‐chemical technology is a relatively green and sustainable synthesis method, which opens up a broad application prospect in the field of direct functionalization of C(sp3)−H bonds. In recent years, photo‐/electro‐mediated C(sp3)−H bond alkylation, arylation, alkynylation, esterification, mercaptoylation, sulfidation, and amination of ethers have been extensively studied. In this review, the research progress of photo‐/electro‐mediated C(sp3)−H bond functionalization of ether compounds from 2014 to 2023 is systematically reviewed, and the scope, limitations, and mechanisms for some reactions are discussed. [ABSTRACT FROM AUTHOR]

We report the triply selective and sequential diversification of a single Csp3 carbon carrying Cl, Bpin and GeEt3 for the modular and programmable construction of sp3‐rich molecules. Various functionalizations of Csp3−Cl and Csp3−BPin (e.g. alkylation, arylation, homologation, amination, hydroxylation) were tolerated by the Csp3−GeEt3 group. Moreover, the methodological repertoire of alkyl germane functionalization was significantly expanded beyond the hitherto known Giese addition and arylation to alkynylation, alkenylation, cyanation, halogenation, azidation, C−S bond formation as well as the first demonstration of stereo‐selective functionalization of a Csp3‐[Ge] bond. [ABSTRACT FROM AUTHOR]

Photoredox catalysis has become a mainstay in synthetic methodology over the past decade. However, its application in the functionalization of natural products remains to be further explored. Herein, we report an efficient approach to synthesize artemisinin G from artemisinin via photocatalysis in high yield. [ABSTRACT FROM AUTHOR]

As one of the six major nutrients, lipids play important roles in various biological processes, including cell membrane construction, signal transduction, and energy metabolism. The diverse functions of lipids are intricately linked to the distinct structures. More than 48 000 molecular lipid structures have been curated in the database which can be further categorized into 8 categories and more than one hundred lipid classes and subclasses. The diverse structures of lipids pose challenges for their lipidomic analysis, especially the co-existence of isomers and isobar. Traditional tandem mass spectrometry (MS/MS) techniques based on collision-induced dissociation (CID) can provide the informations of molecular species and acyl chain composition of various types of lipids in a sensitive fashion. However, they typically fall short in providing detailed structural information, including C=C positions, sn-positions, functional group substitutions and their locations on the fatty acyl chains. In recent years, mass spectrometry methods capable of distinguishing lipid isomers at various structural levels have been developed, among which radical chemistry plays important role in both gas-phase ion activation and chemical derivatization. This article summarized the MS/MS techniques for lipid structural analysis at detailed structural levels via harnessing the power of both radical chemistry and tandem mass spectrometry in the past decade. Radical-induced dissociation (RID) refers to a group of gas-phase dissociation methods which can generate intrachain C-C cleavages in the fatty acyl chain and thus produce fragmentation patterns useful for identification of chain modification. Ultraviolet photodissociation (UVPD) and CID triggered radical-directed dissociation, and electron impact excitation of ions from organics (EIEIO) are the major RID methods. By coupling RID with separation methods, such as reversed-phase liquid chromatography (RPLC), identification and quantitation of lipid isomers consisting of methyl branching, hydroxy group, and cyclopropane modification and their locations have been achieved. The two major derivatization methods utilizing radical chemistry for C=C bond modification were discussed, including radical initiated epoxidation reactions and the Paternò-Büchi reaction. Furthermore, the future direction of combining radical chemistry and tandem mass spectrometry for deep lipidotyping was discussed, which included the coupling with advanced separation methods, integrated workflows for multi-level structure analysis, and development of automated annotation tools for data analysis.

Whereas indications of radical reactivity in bismuth compounds can be traced back to the 19th century, the preparation and characterization of both transient and persistent bismuth‐radical species has only been established in recent decades. These advancements led to the emergence of the field of bismuth radical chemistry, mirroring the progress seen for other main‐group elements. The seminal and fundamental studies in this area have ultimately paved the way for the development of catalytic methodologies involving bismuth‐radical intermediates, a promising approach that remains largely untapped in the broad landscape of synthetic organic chemistry. In this review, we delve into the milestones that eventually led to the present state‐of‐the‐art in the field of radical bismuth chemistry. Our focus aims at outlining the intrinsic discoveries in fundamental inorganic/organometallic chemistry and contextualizing their practical applications in organic synthesis and catalysis. [ABSTRACT FROM AUTHOR]

The pollution of atmospheric ozone in China shows an obvious upward trend in the past decade. However, the studies on the atmospheric oxidation capacity and O 3 formation in four seasons in the southeastern coastal region of China with the rapid urbanization remain limited. Here, a four-season field observation was carried out in a coastal city of southeast China, using an observation-based model combining with the Master Chemical Mechanism, to explore the atmospheric oxidation capacity (AOC), radical chemistry, O 3 formation pathways and sensitivity. The results showed that the average net O 3 production rate (14.55 ppbv/hr) in summer was the strongest, but the average O 3 concentrations in autumn was higher. The AOC and RO x levels presented an obvious seasonal pattern with the maximum value in summer, while the OH reactivity in winter was the highest with an average value of 22.75 sec−1. The OH reactivity was dominated by oxygenated VOCs (OVOCs) (30.6%-42.8%), CO (23.2%-26.8%), NO 2 (13.6%-22.0%), and alkenes (8.4%-12.5%) in different seasons. HONO photolysis dominated OH primary source on daytime in winter, while in other seasons, HONO photolysis in the morning and ozone photolysis in the afternoon contributed mostly. Sensitivity analysis indicated that O 3 production was controlled by VOCs in spring, autumn and winter, but a VOC-limited and NO x -limited regime in summer, and alkene and aromatic species were the major controlling factors to O 3 formation. Overall, the study characterized the atmospheric oxidation capacity and elucidated the controlling factors for O 3 production in the coastal area with the rapid urbanization in China. [ABSTRACT FROM AUTHOR]

Radical-polar crossover (RPC) reaction bridges the gap between one- and two-electron reactivities, thus providing an ideal solution to overcome the limitations of both radical and polar chemistry. In this manifold, organic electrochemistry provides a uniquely facile strategy to access a diverse array of radical intermediates, thus broadening the chemical space of the RPC concept. This review highlights the synthetic advances in the field of electrochemical RPC reactions since 2020, with an emphasis on the substrate scope, reaction limitation and mechanistic aspect. The related RPC reactions are categorized as net-oxidative, net-reductive, or redox neutral transformations. [ABSTRACT FROM AUTHOR]

We herein describe a protocol to synthesize trifluoromethylated alkyl boronates from alkenes by the mutual activation of the Togni II and the bis(catecholato)diboron reagents in the absence of any catalyst and additives. This reaction enables synthesizing a series of trifluoromethylated alkyl boronates using unactivated alkenes, including natural products and drug derivatives, in a regioselective manner. Moreover, the synthetic utility of the boronic ester present in the product allows access to a range of trifluoromethyl containing compounds. The radical trapping and gas detection experiments reveal that the more Lewis acidic diboron reagent determines the rapid formation of trifluoromethyl and boron centered radicals. [ABSTRACT FROM AUTHOR]

As one of the six major nutrients, lipids play important roles in various biological processes, including cell membrane construction, signal transduction, and energy metabolism. The diverse functions of lipids are intricately linked to the distinct structures. More than 48 000 molecular lipid structures have been curated in the database which can be further categorized into 8 categories and more than one hundred lipid classes and subclasses. The diverse structures of lipids pose challenges for their lipidomic analysis, especially the co-existence of isomers and isobar. Traditional tandem mass spectrometry (MS/MS) techniques based on collision-induced dissociation (CID) can provide the informations of molecular species and acyl chain composition of various types of lipids in a sensitive fashion. However, they typically fall short in providing detailed structural information, including C=C positions, sn-positions, functional group substitutions and their locations on the fatty acyl chains. In recent years, mass spectrometry methods capable of distinguishing lipid isomers at various structural levels have been developed, among which radical chemistry plays important role in both gas-phase ion activation and chemical derivatization. This article summarized the MS/MS techniques for lipid structural analysis at detailed structural levels via harnessing the power of both radical chemistry and tandem mass spectrometry in the past decade. Radical-induced dissociation (RID) refers to a group of gas-phase dissociation methods which can generate intrachain C-C cleavages in the fatty acyl chain and thus produce fragmentation patterns useful for identification of chain modification. Ultraviolet photodissociation (UVPD) and CID triggered radical-directed dissociation, and electron impact excitation of ions from organics (EIEIO) are the major RID methods. By coupling RID with separation methods, such as reversed-phase liquid chromatography (RPLC), identification and quantitation of lipid isomers consisting of methyl branching, hydroxy group, and cyclopropane modification and their locations have been achieved. The two major derivatization methods utilizing radical chemistry for C=C bond modification were discussed, including radical initiated epoxidation reactions and the Paternò-Büchi reaction. Furthermore, the future direction of combining radical chemistry and tandem mass spectrometry for deep lipidotyping was discussed, which included the coupling with advanced separation methods, integrated workflows for multi-level structure analysis, and development of automated annotation tools for data analysis. [ABSTRACT FROM AUTHOR]

Plasmodium falciparum is a fast-evolving parasite responsible for the fatal disease malaria, making it crucial to renew our therapeutic arsenal. Modulating the artemisinin’s endoperoxide pharmacophore is a promising route to synthesizing new antimalarial derivatives. For the first step of our 20 mmol scale synthesis, catalyzed by manganese (III) acetylacetonate, we applied the conditions previously described in the literature to one of our low-yielding asymmetrically disubstituted alkenes, (2-methylallyl)benzene. Under conditions designed for alkyl derivatives, manganese (II) and (III) acetate catalyzed its peroxycyclization with methyl 3-oxobutanoate to a 1,2-dioxane ring in the presence of oxygen from air at room temperature with a 36% yield, while an oxygen atmosphere, as described in the literature, decreased the yield to 7%. Finally, under conditions designed for aryl derivatives, the yield was reduced to 30%, showing that methylallyl derivatives have an intermediate reactivity that needs further optimization to produce 1,2-dioxane ring by manganese catalyzation in good yields. This work characterizes the product obtained and discusses the most suitable reaction conditions.

Radical chemistry is one of the most important methods used in modern polymer science and industry. Over the past century, new knowledge on radical chemistry has both promoted and been generated from the emergence of polymer synthesis and modification techniques. In this review, we discuss radical chemistry in polymer science from four interconnected aspects. We begin with radical polymerization, the most employed technique for industrial production of polymeric materials, and other polymer synthesis involving a radical process. Post-polymerization modification, including polymer crosslinking and polymer surface modification, is the key process that introduces functionality and practicality to polymeric materials. Radical depolymerization, an efficient approach to destroy polymers, finds applications in two distinct fields, semiconductor industry and environmental protection. Polymer chemistry has largely diverged from organic chemistry with the fine division of modern science but polymer chemists constantly acquire new inspirations from organic chemists. Dialogues on radical chemistry between the two communities will deepen the understanding of the two fields and benefit the humanity.

1,3‐Bis(boronic) esters can be readily synthesized from alkylBpin precursors. Selective transformations of these compounds hold the potential for late‐stage functionalization of the remaining C−B bond, leading to a diverse array of molecules. Currently, there are no strategies available to address the reactivity and, more importantly, the controllable regiodivergent functionalization of 1,3‐bis(boronic) esters. In this study, we have achieved controllable regiodivergent alkynylation of these molecules. The regioselectivity has been clarified based on the unique chelation patterns observed with different organometallic reagents. Remarkably, this methodology effectively addresses the low reactivity of 1,3‐bis(boronic) esters and bridges the gap in radical chemistry, which typically yields only the classical products formed via stable radical intermediates. Furthermore, the compounds synthesized through this approach serve as potent building blocks for creating molecular diversity. [ABSTRACT FROM AUTHOR]

The utilization of photo‐induced processes in C−H functionalization via radical pathways has emerged as a highly promising strategy for the preparation and modification of complex organic compounds. While current methods for generating carbon‐centred radicals from C−H bonds primarily focus on hydridic C−H bonds to yield nucleophilic radical species, the reactivity and potential applications of electrophilic radicals derived from protic C−H bonds remain largely unexplored. In this review, we aim to shed light on the seminal findings regarding the activation of protic C(sp3)−H bonds while also showcasing noteworthy examples of this radical formation process. Mechanistically diverse modes of activation are discussed, unified by proton‐coupled electron transfer (PCET) concepts. [ABSTRACT FROM AUTHOR]

Our current unhealthy lifestyle and the exponential surge in the population getting affected by a variety of diseases have made pharmaceuticals or drugs an imperative part of life, making the development of innovative strategies for drug discovery or the introduction of refined, cost‐effective and modern technologies for the synthesis of clinically used drugs, a need of the hour. Ever since their discovery, free radicals and radical cations or anions as reactive intermediates have captivated the chemists, resulting in an exceptional utilization of these moieties throughout the field of chemical synthesis, owing to their unprecedented and widespread reactivity. Sticking with the idea of not judging the book by its cover, despite the conventional thought process of radicals being unstable and difficult to control entities, scientists and academicians around the globe have done an appreciable amount of work utilizing both persistent as well as transient radicals for a variety of organic transformations, exemplifying them with the synthesis of significant biologically active pharmaceutical ingredients. This review truly accounts for the organic radical transformations including radical addition, radical cascade cyclization, radical/radical cross‐coupling, coupling with metal‐complexes and radical cations coupling with nucleophiles, that offers fascinating and unconventional approaches towards the construction of intricate structural frameworks of marketed APIs with high atom‐ and step‐economy; complementing the otherwise employed traditional methods. This tutorial review presents a comprehensive package of diverse methods utilized for radical generation, featuring their reactivity to form critical bonds in pharmaceutical total synthesis or in building key starting materials or intermediates of their synthetic journey, acknowledging their excellence, downsides and underlying mechanisms, which are otherwise poorly highlighted in the literature. Despite great achievements over the past few decades in this area, many challenges and obstacles are yet to be unraveled to shorten the distance between the academics and the industry, which are all discussed in summary and outlook. [ABSTRACT FROM AUTHOR]

Researching and utilizing radical intermediates in organic synthetic chemistry have innovated discoveries in methodology and theory. Reactions concerning free radical species opened new pathways beyond the frame of the two‐electron mechanism while commonly characterized as rampant processes lacking selectivity. As a result, research in this field has always focused on the controllable generation of radical species and determining factors of selectivity. Metal‐organic frameworks (MOFs) have emerged as compelling candidates as catalysts in radical chemistry. From a catalytic point of view, the porous nature of MOFs entails an inner phase for the reaction that could offer possibilities for the regulation of reactivity and selectivity. From a material science perspecti ve, MOFs are organic‐inorganic hybrid materials that integrate functional units in organic compounds and complex forms in the tunable long‐ranged periodic structure. In this account, we summarized our progress in the application of MOFs in radical chemistry in three parts: (1) The generation of radical species; (2) The weak interactions and site selectivity; (3) Regio‐ and stereo‐selectivity. The unique role of MOFs play in these paradigms is demonstrated in a supramolecular narrative through the analyses of the multi‐constituent collaboration within the MOF and the interactions between MOFs and the intermediates during the reactions. [ABSTRACT FROM AUTHOR]

The use of free radicals as organocatalysts constitutes a powerful strategy to activate and functionalize unsaturated carbon chains. Indeed, the unique affinity of open‐shell species for alkenes and alkynes can be rerouted to achieve the catalytic covalent activation of the substrate and control a subsequent radical cascade. However, the field of covalent radical catalysis has remained challenging for decades due to important issues in terms of catalyst handling, reaction design and viability. Recently, these pitfalls have been addressed one by one by the use of photocatalysis to control the generation and the reactivity of radical catalysts. This Concept article aims to highlight recent achievements in the field of photocatalyzed covalent radical catalysis and the perspectives offered by such catalytic combinations. The reaction mechanisms and the interconnection between the catalytic cycles are reviewed with the hope of demonstrating the synthetic potential of this approach and foster a rapid growth of this nascent topic. [ABSTRACT FROM AUTHOR]

The review covers research published since 2017 and is focused on enantioselective synthesis using radical reactions. It describes recent approaches to the asymmetric synthesis of chiral molecules based on the application of the metal catalysis, dual metal and organocatalysis and finally, pure organocatalysis including enzyme catalysis. This review focuses on the synthetic aspects of the methodology and tries to show which compounds can be obtained in enantiomerically enriched forms. [ABSTRACT FROM AUTHOR]

Due to their strong covalent bonds and low reduction potentials, activating inert substrates is challenging. Recent advances in photoredox catalysis offered a number of solutions, each of which useful for activating specific inert bonds. Developing a general catalytic platform that can consistently target a broad range of inert substrates would be synthetically useful. Herein, we report a readily available indole thiolate organocatalyst that, upon excitation with 405 nm light, acquires a strongly reducing power. This excited‐state reactivity served to activate, by single‐electron reduction, strong C−F, C−Cl, and C−O bonds in both aromatic and aliphatic substrates. This catalytic platform was versatile enough to promote the reduction of generally recalcitrant electron‐rich substrates (Ered<−3.0 V vs SCE), including arenes that afforded 1,4‐cyclohexadienes. The protocol was also useful for the borylation and phosphorylation of inert substrates with a high functional group tolerance. Mechanistic studies identified an excited‐state thiolate anion as responsible of the highly reducing reactivity. [ABSTRACT FROM AUTHOR]

A photoinduced synthesis of β‐keto thiosulfone/β‐keto selenosulfone by the reaction of α‐bromoacetophenone with thiosulfonate/selenosulfonate under metal‐free and visible light irradiation conditions is developed. Two C−S bonds or one C−S bond and one C−Se bond were constructed simultaneously. [ABSTRACT FROM AUTHOR]

The radiolytic degradation chemistry of three phenylated analogs of N,N,N',N'-tetraoctyl diglycolamide (TODGA) was investigated: 2-(2-(di-n-octylamino)-2-oxoethoxy)-N,N-di-n-octyl-2-phenylacetamide (PhTODGA), which has a phenyl substituent bound to a central methylene, 2-(2-(di-n-octylamino)-2-oxo-1-phenylethoxy)-N,N-di-n-octylpropanamide (PhMeTODGA), which also contains a methyl substituent bound to the methylene on the other side of the ether moiety, and, 2-(2-N-n-hexyl-N-phenylamino)-2-oxoethoxy)-N-n-hexyl-N-phenylacetamide (DHDPDGA), which has phenyl substituents located on the amide groups instead of the central methylenes. In Part II of this series of papers radiolytic degradation products were identified after separation with liquid chromatography by High Resolution, Accurate-Mass mass spectrometry and collision-induced dissociation. At least twenty-two radiolytic degradation products were identified for PhTODGA, twenty-nine for PhMeTODGA, and over three dozen for DHDPDGA. The suite of radiolytic degradation products of these three investigated ligands was significantly larger than has been reported for previously studied diglycolamides, owing to their asymmetric nature, and to the identification of several new degradation mechanisms, including addition of methyl, hydroxyl, and nitrogen oxide radicals, that have not been previously reported for diglycolamides. Degradation products that contained addition of a NO2 or NO3 group were particularly prevalent for DHDPDGA, likely due to the phenyl side-groups. Several of these newly observed mechanisms do not appear to depend on the presence of the phenyl groups, suggesting these novel mechanisms may apply to other diglycolamides [ABSTRACT FROM AUTHOR]

Boron-containing materials, and in particular boron nitride, have recently been identified as highly selective catalysts for the oxidative dehydrogenation of alkanes such as propane. To date, no mechanism exists that can explain both the unprecedented selectivity, the observed surface oxyfunctionalization, and the peculiar kinetic features of this reaction. We combine catalytic activity measurements with quantum chemical calculations to put forward a bold new hypothesis. We argue that the remarkable product distribution can be rationalized by a combination of surface-mediated formation of radicals over metastable sites, and their sequential propagation in the gas phase. Based on known radical propagation steps, we quantitatively describe the oxygen pressure-dependent relative formation of the main product propylene and by-product ethylene. Free radical intermediates most likely differentiate this catalytic system from less selective vanadium-based catalysts.

The enantioselective total synthesis of the rearranged spongian diterpenoid (-)-macfarlandin C is reported. This is the first synthesis of a rearranged spongian diterpenoid in which the bulky hydrocarbon fragment is joined via a quaternary carbon to the highly hindered concave face of the cis-2,8-dioxabicyclo[3.3.0]octan-3-one moiety. The strategy involves a late-stage fragment coupling between a tertiary carbon radical and an electrophilic butenolide resulting in the stereoselective formation of vicinal quaternary and tertiary stereocenters. A stereoselective Mukaiyama hydration that orients a pendant carboxymethyl side chain cis to the bulky octahydronapthalene substituent was pivotal in fashioning the challenging concave-substituted cis-dioxabicyclo[3.3.0]octanone fragment.

The glycyl radical enzyme (GRE) superfamily utilizes a glycyl radical cofactor to catalyze difficult chemical reactions in a variety of anaerobic microbial metabolic pathways. Recently, a GRE, trans-4-hydroxy-L-proline (Hyp) dehydratase (HypD), was discovered that catalyzes the dehydration of Hyp to (S)-Δ1-pyrroline-5-carboxylic acid (P5C). This enzyme is abundant in the human gut microbiome and also present in prominent bacterial pathogens. However, we lack an understanding of how HypD performs its unusual chemistry. Here, we have solved the crystal structure of HypD from the pathogen Clostridioides difficile with Hyp bound in the active site. Biochemical studies have led to the identification of key catalytic residues and have provided insight into the radical mechanism of Hyp dehydration.

As the cross-coupling needs of chemists continue to grow for accessing increasingly complex targets, radical-based transformations have become mainstay methodologies for the discovery of new reactivity under mild and waste-limiting conditions. En route to such methodological advancements, the observation of the 1,2-boron shift a novel radical rearrangement in its application has generated a new cross-coupling methodology to access products that were previously inaccessible or otherwise cumbersome to make. The origins of this radical rearrangement along with the synthetic applications to organic chemistry are highlighted.

Although the direct conversion of gaseous acetylene into value‐added liquid commodity chemicals is becoming increasingly attractive, the majority of the established methodologies are focused on cross‐coupling, hydro‐functionalization, and polymerization. Herein, we describe a 1,2‐difunctionalization method that inserts acetylene directly into readily available bifunctional reagents. This method provides access to diverse C2‐linked 1,2‐bis‐heteroatom products in high regio‐ and stereoselectivity along with opening up previously unexplored synthetic directions. In addition, we demonstrate this method's synthetic potential by converting the obtained products into diverse functionalized molecules and chiral sulfoxide‐containing bidentate ligands. Using a combination of experimental and theoretical methods, the mechanism for this insertion reaction was investigated. [ABSTRACT FROM AUTHOR]