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Hibiscetin, a major bioactive ingredient of Hibiscus sabdariffa, exhibits numerous pharmacological actions and five metal-chelating sites. Since flavonoids play a vital role in scavenging or reducing the toxicity of redox-active metal ions, the chelation of Fe2+ cation by the flavonoid Hibiscetin was examined using the DFT method carried out at the M06-2X/6-311+G(d, p)/LANL2DZ level of theory in the aqueous phase. All the complexed species derived from neutral and deprotonated ligand forms were considered. The results show that the oxygen atoms of the di-deprotonated catechol moiety at the C-7 and C-8 positions of Hibiscetin interact best with the Fe2+ ion among the possible chelation sites on Hibiscetin. The stability of the most stable complex, HIB-[7-8] -Fe2+, was validated by Frontier molecular orbital, Natural bond orbital, and natural population reports. The topological analysis indicated the electrostatic interaction between the oxygen atoms of Hibiscetin and the metal ion in the complex. The investigation of the radical scavenging capabilities in gas, water, and benzene media proved the superior antioxidant activity of the most stable complex of Hibiscetin and Fe2+ ion when compared to parent flavonoid. The hydrogen atom transfer (HAT), single-electron transfer followed by proton transfer (SET-PT), and sequential proton-loss electron transfer (SPLET) mechanisms were studied, and the HAT mechanism was found to be the most effective radical scavenging mechanism in the gas and non-polar solvent and the SPLET mechanism in the polar solvent. The best site for radical attack is identified to be 4'-OH. [ABSTRACT FROM AUTHOR]

Machine learning combined with density functional theory (DFT) enables rapid exploration of catalyst descriptors space such as adsorption energy, facilitating rapid and effective catalyst screening. However, there is still a lack of models for predicting adsorption energies on oxides, due to the complexity of elemental species and the ambiguous coordination environment. This work proposes an active learning workflow (LeNN) founded on local electronic transfer features (e) and the principle of coordinate rotation invariance. By accurately characterizing the electron transfer to adsorption site atoms and their surrounding geometric structures, LeNN mitigates abrupt feature changes due to different element types and clarifies coordination environments. As a result, it enables the prediction of *H adsorption energy on binary oxide surfaces with a mean absolute error (MAE) below 0.18 eV. Moreover, we incorporate local coverage (θ1) and leverage neutral network ensemble to establish an active learning workflow, attaining a prediction MAE below 0.2 eV for 5419 multi-*H adsorption structures. These findings validate the universality and capability of the proposed features in predicting *H adsorption energy on binary oxide surfaces. [ABSTRACT FROM AUTHOR]

Natural photosynthesis enzymes utilize energies of several photons for challenging oxidation of water, whereas artificial photo‐catalysis typically involves only single‐photon excitation. Herein, a multiphoton excitation strategy is reported that combines parallel photo‐excitations with a photoinduced electron transfer process for the activation of C(sp3)─H bonds, including methane. The metal–organic framework Fe3‐MOF is designed to consolidate 4,4′,4″‐nitrilotrisbenzoic units for the photoactivation of dioxygen and trinuclear iron clusters as the HAT precursor for photoactivating alkanes. Under visible light irradiation, the dyes and iron clusters absorbed parallel photons simultaneously to reach their excited states, respectively, generating 1O2 via energy transfer and chlorine radical via ligand‐to‐metal charge transfer. The further excitation of organic dyes leads to the reduction of 1O2 into O2•− through a photoinduced electron transfer, guaranteeing an extra multiphoton oxygen activation manner. The chlorine radical abstracts a hydrogen atom from alkanes, generating the carbon radical for further oxidation transformation. Accordingly, the total oxidation conversion of alkane utilizing three photoexcitation processes combines the energies of more than two photons. This new platform synergistically combines a consecutive excited photoredox organic dye and a HAT catalyst to combine the energies of more than two photons, providing a promising multiphoton catalysis strategy under energy saving, and high efficiency. [ABSTRACT FROM AUTHOR]

A visible‐light‐initiated energy‐transfer enabled radical cyclization for the divergent synthesis of polycyclic γ‐sultine derivatives has been developed. The reaction provides an alternative and expeditious access to benzofused γ‐sultine frameworks, the analogues of γ‐lactones and γ‐sultones, and features good functional group compatibility, mild reaction conditions and excellent diastereoselectivity. The robustness and application potential of this method have also been successfully displayed by two gram‐scale reactions and the synthesis of polycyclic sultones. Mechanistic studies indicated the transformations through a possible energy‐transfer enabled intramolecular radical homolytic substitution or hydrogen atom transfer process mainly. [ABSTRACT FROM AUTHOR]

The γ C-H amination of carboxylic acid presents a promising and sustainable strategy for synthesizing high-value pharmaceutical chemicals. Radical reaction pathways initiated by aroyloxy radical-involved hydrogen atom transfer (HAT) provide diverse but challenging opportunities for remote C-H functionalization. In this report, the first example of intramolecular γ C-H amination of carboxylic acids using a commercially available oxime auxiliary has been achieved. This innovative approach employs a radical relay chaperone, facilitating selective C-H functionalization via 1,5-HAT/radical cross-coupling and enabling the net incorporation of ammonia at the γ carbon of carboxylic acids. In addition, this protocol enables the recycling of the by-product benzophenone, and both product isolation and by-product recycling are silica gel-free. The reactions offer high chemo- and regio-selectivities, operate under mild reaction conditions, boast a broad substrate scope, exhibit good functional group compatibility, and are easily scalable. [ABSTRACT FROM AUTHOR]

A single-step phenylation at the non-acidic C(sp3)–H bond attached to the heteroatom of ethers and N -Boc-amines has been achieved using photoexcited 4-benzoylpyridine as a hydrogen atom transfer (HAT) catalyst. The design of electron-deficient (trifluoromethylsulfonyl)benzene derivatives, as a phenyl precursor, was critical to realizing the present transformation. Moreover, the DFT calculations indicated that the present transformation proceeds via a concerted homolytic aromatic substitution rather than via a stepwise one involving the formation of a cyclohexadienyl radical intermediate. [ABSTRACT FROM AUTHOR]

In this study, we introduce a novel intramolecular hydrogen atom transfer (HAT) reaction that efficiently yields azetidine, oxetane, and indoline derivatives through a mechanism resembling the carbon analogue of the Norrish‐Yang reaction. This process is facilitated by excited triplet‐state carbon‐centered biradicals, enabling the 1,5‐HAT reaction by suppressing the critical 1,4‐biradical intermediates from undergoing the Norrish Type II cleavage reaction, and pioneering unprecedented 1,6‐HAT reactions initiated by excited triplet‐state alkenes. We demonstrate the synthetic utility and compatibility of this method across various functional groups, validated through scope evaluation, large‐scale synthesis, and derivatization. Our findings are supported by control experiments, deuterium labeling, kinetic studies, cyclic voltammetry, Stern–Volmer experiments, and density functional theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

An organophotocatalytic method has been described towards the synthesis of indolines and oxindoles starting from unusual α-chloro amide and N-(2-chlorophenyl)-N-alkyl methacrylamide substrates. This marks a notable improvement since the earlier syntheses utilized iridium and gold catalysts, and involved C–I or C–Br bond cleavage as the initial step. Our photocatalyst is a pincer ligand that can be easily deprotonated to make a very strong reducing agent. The reductive cleavage of the carbon–chloride bond, and subsequent 5-exo-trig ring cyclization, followed by hydrogen atom abstraction, prepare the desired heterocycles under very mild reaction conditions. An atom economic use of KOtBu has been shown to demonstrate the unusual trifunctional role of the latter. [ABSTRACT FROM AUTHOR]

The radical Truce–Smiles rearrangement is a straightforward strategy for incorporating aryl groups into organic molecules for which asymmetric processes remains rare. By employing a readily available and non‐expensive chiral auxiliary, we developed a highly efficient asymmetric photocatalytic acyl and alkyl radical Truce–Smiles rearrangement of α‐substituted acrylamides using tetrabutylammonium decatungstate (TBADT) as a hydrogen atom–transfer photocatalyst, along with aldehydes or C−H containing precursors. The rearranged products exhibited excellent diastereoselectivities (7 : 1 to >98 : 2 d.r.) and chiral auxiliary was easily removed. Mechanistic studies allowed understanding the transformation in which density functional theory (DFT) calculations provided insights into the stereochemistry‐determining step. [ABSTRACT FROM AUTHOR]

Here, we report CdS quantum dot (QD) gels, a three‐dimensional network of interconnected CdS QDs, as a new type of direct hydrogen atom transfer (d‐HAT) photocatalyst for C−H activation. We discovered that the photoexcited CdS QD gel could generate various neutral radicals, including α‐amido, heterocyclic, acyl, and benzylic radicals, from their corresponding stable molecular substrates, including amides, thio/ethers, aldehydes, and benzylic compounds. Its C−H activation ability imparts a broad substrate and reaction scope. The mechanistic study reveals that this reactivity is intrinsic to CdS materials, and the neutral radical generation did not proceed via the conventional sequential electron transfer and proton transfer pathway. Instead, the C−H bonds are activated by the photoexcited CdS QD gel via a d‐HAT mechanism. This d‐HAT mechanism is supported by the linear correlation between the logarithm of the C−H bond activation rate constant and the C−H bond dissociation energy (BDE) with a Brønsted slope α=0.5. Our findings expand the currently limited direct hydrogen atom transfer photocatalysis toolbox and provide new possibilities for photocatalytic C−H activation. [ABSTRACT FROM AUTHOR]

Metal hydrides are crucial intermediates in numerous catalytic reactions. Intensive efforts have been dedicated to constructing molecular metal hydrides, where toxic precursors and delicate mediators are usually involved. Herein, we demonstrate a facile pressure-induced methodology to generate a cost-effective heterogeneous electrocatalytic metal hydride surface for sustainable hydrogen transfer. Taking carbon dioxide (CO2) electroreduction as a model system and zinc (Zn), a well-known carbon monoxide (CO)-selective catalyst, as a model catalyst, we showcase a homogeneous-type hydrogen atom transfer process induced by heterogeneous hydride surfaces, enabling direct hydrogenation pathways traditionally considered "prohibited". Specifically, the maximal Faradaic efficiency for formate is enhanced by ~fivefold to 83% under ambient conditions. Experimental and theoretical analyses reveal that unlike the distal hydrogenation route for CO2 to CO over pristine Zn, the Zn hydride surface enables direct hydrogenation at the carbon site of CO2 to form formate. This work provides a promising material platform for sustainable synthesis. The authors demonstrate a facile pressure-induced methodology to generate a cost-effective heterogeneous electrocatalytic metal hydride surface for sustainable hydrogen transfer. [ABSTRACT FROM AUTHOR]

This paper presents the synthesis and characterization of a series of novel monomeric aqua‐ligated iron(III) complexes, [FeIII(L5R)(OH2)]2+ (R=OMe, H, Cl, NO2), supported by an amide‐containing pentadentate N5 donor ligand, L5R [HL5R=2‐(((1‐methyl‐1H‐imidazol‐2‐yl)methyl)(pyridin‐2‐yl‐methyl)amino)‐N‐(5‐R‐quinolin‐8‐yl)acetamide]. The complexes were characterized by various spectroscopic and analytical techniques, including electrochemistry and magnetic measurements. The Fe(III)‐hydroxo complexes, [FeIII(L5R)(OH)]1+, were generated in situ by deprotonating the corresponding aqua complexes in a pH ~7 aqueous medium. In another way, adding one equivalent of a base to a methanolic solution of the Fe(III)‐aqua complexes also produced the Fe(III)‐hydroxo complexes. The study uses linoleic fatty acid as a substrate to explore the hydrogen atom abstraction (HAA) reactivity of both hydroxo and aqua complexes. The investigation highlights the substitution effect of the L5R ligand on reactivity, revealing a higher rate when an electron‐withdrawing group is present. Hammett analyses and(or) determination of the asynchronicity factor (η) suggest an oxidative asynchronous concerted proton‐electron transfer (CPET) pathway for the HAA reactions. Aqua complexes exhibited a higher asynchronicity in CPET, resulting in higher reaction rates than their hydroxo analogs. Overall, the work provides insights into the beneficial role of a higher imbalance in electron‐transfer‐proton‐transfer (ET‐PT) contributions in HAA reactivity. [ABSTRACT FROM AUTHOR]

Recent years have seen increasing interest in uranyl(VI) photocatalysis. In this study, uranyl complexes were successfully synthesized from ligands L1–L6 and UO2(NO3)2·6H2O under reflux conditions, yielding products 1–6 with yields ranging from 30% to 50%. The complexes were thoroughly characterized using NMR spectroscopy, single-crystal X-ray diffraction, and elemental analysis. The results indicate that complexes 1–5 possess a pentagonal bipyramidal geometry, whereas complex 6 exhibits an octahedral structure. The photocatalytic properties of these novel complexes for sp3 C-H bond functionalization were explored. The results demonstrate that complex 4 functions as an efficient photocatalyst for converting C-H bonds to C-C bonds via hydrogen atom transfer under blue light irradiation. [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]

The direct functionalization of remote C(sp3)–H is valuable but challenging, and is even more difficult to achieve than the γ-C(sp3)–H functionalization of alcohols. Among the strategies, hydrogen atom transfer (HAT) is one of the solutions for such transformations. Herein, we designed a migration reaction involving carbon monoxide, forming an alkoxy radical by photocatalysis, and used carbon monoxide to extend the carbon chain to provide a site for the migration of heteroaryl groups, which makes 1,4-HAT more advantageous, and we relied on this strategy to successfully achieve the synthesis of 1,4-dicarbonyl compounds by γ-C(sp3) functionalization of alcohols. [ABSTRACT FROM AUTHOR]

Understanding the properties of small particles working under high-temperature conditions at the atomistic scale is imperative for exact control of related processes, but it is quite challenging to achieve experimentally. Herein, benefitting from state-of-the-art mass spectrometry and by using our newly designed high-temperature reactor, the activity of atomically precise particles of negatively charged vanadium oxide clusters toward hydrogen atom abstraction (HAA) from methane, the most stable alkane molecule, has been measured at elevated temperatures up to 873 K. We discovered the positive correlation between the reaction rate and cluster size that larger clusters possessing greater vibrational degrees of freedom can carry more vibrational energies to enhance the HAA reactivity at high temperature, in contrast with the electronic and geometric issues that control the activity at room temperature. This finding opens up a new dimension, vibrational degrees of freedom, for the simulation or design of particle reactions under high-temperature conditions. [ABSTRACT FROM AUTHOR]

Vibrational relaxation of H2O(v2,v13) molecules by collisions with Ar was studied at 298 K (v2 denotes the bending vibrational mode and v13 denotes the sum of the symmetric, v1, and asymmetric, v3, vibrational modes). The H2O molecules from 14 different exothermic reactions of H-atom abstraction by OH radicals were observed by infrared emission from a fast flow reactor as a function of Ar pressure and reaction time. Numerical kinetic calculations were used to obtain rate constants for stretch-to-bend energy conversion, (v2,v13) → (v2 + 2,v13 − 1), and pure bend relaxation, (v2,v13) → (v2 − 1,v13). Rate constants for states up to v13 = 4 were based on the average values from all reactions. The rate constant for the (2,0) → (1,0) bending relaxation is in agreement with the published values from laser-induced fluorescent experiments; the rate constants for higher levels increase with v2. Our average rate constant for the (0,1) → (2,0) stretch-to-bend conversion is somewhat smaller but falls within the uncertainty limit of the published value. The average rate constants for the stretch-to-bend process for (01), (02), (03), and (04) stretching states are (4.3 ± 0.8) × 10−14, (7.7 ± 1.1) × 10−14, (14.3 ± 4.2) × 10−14, and (20.6 ± 6.2) × 10−14 cm3 molecule−1 s−1, respectively. [ABSTRACT FROM AUTHOR]

In this work, the pressure- and temperature-dependent reaction rate constants for the hydrogen abstraction and addition of hydroxyl radicals to the unsaturated cyclopentene were studied. Geometries and vibrational frequencies of reactants, products, and transition states were calculated using density functional theory, with single-point energy corrections determined at the domain-based local pair natural orbital-coupled-cluster single double triple/cc-pVTZ-F12 level. The high-pressure limit rate constants were calculated using the canonical variational transition state theory with the small-curvature tunneling approximation. The vibrational partition functions were corrected by the effects of torsional and ring-puckering anharmonicities of the transition states and cyclopentene, respectively. Variational effects are shown to be relevant for all the hydrogen abstraction reactions. The increasing of the rate constants by tunneling is significant at temperatures below 500 K. The pressure dependence on the rate constants of the addition of OH • to cyclopentene was calculated using the system-specific quantum Rice–Ramsperger–Kassel model. The high-pressure limit rate constants decrease with increasing temperature in the range 250–1000 K. The falloff behavior was studied at several temperatures with pressures varying between 10−3 and 103 bar. At temperatures below 500 K, the effect of the pressure on the addition rate constant is very modest. However, at temperatures around and above 1000 K, taking pressure into account is mandatory for an accurate rate constant calculation. Branching ratio analyses reveal that the addition reaction dominates at temperatures below 500 K, decreasing rapidly at higher temperatures. Arrhenius parameters are provided for all reactions and pressure dependent Arrhenius parameters are given for the addition of OH • to cyclopentene. [ABSTRACT FROM AUTHOR]

The nitro moiety is an indispensable functional group in organic synthesis due to its facile introduction and reduction to the corresponding amines for a plethora of organic transformations. Owing to its distinct electronegative and conventional properties, it has been used for activated aromatic nucleophilic substitution (SNAr) reactions, Smiles reactions, Henry reactions, acyl anion equivalents, etc. Recently, the excellent photochemical properties of nitroarenes have been rediscovered by several groups, and their untapped potential in organic synthesis under UV or visible light irradiation has been exploited. Photoexcited nitroarenes can undergo facile reduction to amines, azo-coupling, metal-free reductive C--N coupling with boronic acids via a 1,2-boronate shift, hydrogen atom transfer (HAT), oxygen atom transfer for anaerobic oxidation of organic molecules, molecular editing via nitrene intermediates, denitrative coupling of β-nitrostyrene, radical α-alkylation of nitroalkanes, etc. They have also been used as a photolabile protecting group in medicinal chemistry and chemical biology applications. Here, we summarise the recent findings on visible-light-mediated transformations involving nitro-containing organic molecules. [ABSTRACT FROM AUTHOR]

A supramolecular naphthalenediimide radical anion was developed through host--guest interactions between NDI and cucurbit[7]uril (CB[7]), which can be greatly promoted in the presence of chloride ions to obtain Cl• and NDI-2CB[7]•-. Under the synergistic action of Cl• as a hydrogen atom transfer (HAT) agent and NDI-2CB[7]•- transferring electrons to O2 to produce O2•, the photocatalytic oxidation reactions of alkylarenes to carbonyls can be realized with universal applicability. [ABSTRACT FROM AUTHOR]

A protocol exploiting isocyanides as carbamoylating agents for the α‐C(sp3)‐H functionalization of cyclic ethers has been optimized via a combined visible light‐driven hydrogen atom transfer/Lewis acid‐catalyzed approach. The isocyanide substrate scope revealed an exquisite functional group compatibility (18 examples, with yields up to 99 %). Both radical and polar trapping, kinetic isotopic effect and real‐time NMR studies support the mechanistic hypothesis and provide insightful details for the design of new chemical processes involving the generation of oxocarbenium ions. [ABSTRACT FROM AUTHOR]

Herein, we developed a photoinduced remote selective C(sp3)−H alkylation of protected amines in the presence of cesium formate. The protected amines were synthesized from commercially available inexpensive 2‐iodo benzoyl chloride. Under mild reaction conditions, the in situ generated aryl radical is converted to α‐amidoalkyl radical via [1,5]‐HAT process, which combines with different Michael acceptors and affords corresponding alkylation products in good yields. Preliminary mechanistic studies revealed that formate anion acts as a source of carbon dioxide radical anion (CO2⋅−) and hydrogen atom donor was directly confirmed by isotope‐labeling studies. [ABSTRACT FROM AUTHOR]

Developing methods to directly transform C(sp3) −H bonds is crucial in synthetic chemistry due to their prevalence in various organic compounds. While conventional protocols have largely relied on transition metal catalysis, recent advancements in organocatalysis, particularly with radical NHC catalysis have sparked interest in the direct functionalization of "inert" C(sp3) −H bonds for cross C−C coupling with carbonyl moieties. This strategy involves selective cleavage of C(sp3) −H bonds to generate key carbon radicals, often achieved via hydrogen atom transfer (HAT) processes. By leveraging the bond dissociation energy (BDE) and polarity effects, HAT enables the rapid functionalization of diverse C(sp3)−H substrates, such as ethers, amines, and alkanes. This mini‐review summarizes the progress in carbene organocatalytic functionalization of inert C(sp3)−H bonds enabled by HAT processes, categorizing them into two sections: 1) C−H functionalization involving acyl azolium intermediates; and 2) functionalization of C−H bonds via reductive Breslow intermediates. [ABSTRACT FROM AUTHOR]

Due to the high oxidation potential of arenes and alkenes, previous methods of benzylic and allylic C–H oxidation necessitated the use of strong oxidizing agents, metal catalysts, or free radical initiators (such as photocatalysts or hydrogen atom transfer reagents) to be effective. Herein, we employ oxygen to generate a triple-spin charge transfer state with π-conjugated compounds effectively accessing the triplet excited states of arenes, followed by energy transfer to form singlet oxygen facilitating C–H bond oxidation. Distinct from previous oxidations, it is the first time that a series of natural products and drug molecules (27 examples) are selectively oxidized without any catalysts or additives. The transformation can be implemented under sunlight to produce valuable unsaturated (aromatic) ketones and only water as waste, which meets every one of the 12 principles of green chemistry. [ABSTRACT FROM AUTHOR]

A photocatalyzed formal (3+2) cycloaddition has been developed to construct original polysubstituted α‐SCF3 cyclopentanones in a regio‐ and diastereoselective manner. This building block approach leverages trifluoromethylthio alkynes and branched/linear aldehydes, as readily available reaction partners, in consecutive hydrogen atom transfers and C−C bond formations. Difluoromethylthio alkynes are also compatible substrates. Furthermore, the potential for telescoped reaction starting from alcohols instead of aldehydes was demonstrated, as well as process automatization and scale‐up under continuous microflow conditions. This prompted density functional theory (DFT) calculations to support a radical‐mediated cascade process. [ABSTRACT FROM AUTHOR]

This method describes the iron-promoted amidation of dioxazolone under visible light to obtain aromatic/alkyl substituted amides. The nitrogen radicals formed during this process undergo hydrogen atom transfer (HAT) to form amides through the proton provided by HBpin. This reaction eliminates the need for external chemical oxidants and expensive photocatalysts, and exhibits compatibility with various aryl/alkyl substituted derivatives. This method has good prospects for application and development in organic synthesis and medicine. [ABSTRACT FROM AUTHOR]

A theoretical thermodynamic study was conducted to investigate the antioxidant activity and mechanism of 1,3,4-oxadiazol-2-ylthieno[2,3-d]pyrimidin-4-amine derivatives (OTP) using a Density Functional Theory (DFT) approach. The study assessed how solvent environments influence the antioxidant properties of these derivatives. With the increasing prevalence of diseases linked to oxidative stress, such as cancer and cardiovascular diseases, antioxidants are crucial in mitigating the damage caused by free radicals. Previous research has demonstrated the remarkable scavenging abilities of 1,3,4-oxadiazole derivatives, prompting this investigation into their potential using computational methods. DFT calculations were employed to analyze key parameters, including bond dissociation enthalpy (BDE), ionization potential (IP), proton dissociation enthalpy (PDE), and electron transfer enthalpy (ETE), to delineate the antioxidant mechanisms of these compounds. Our findings indicate that specific electron-donating groups such as amine on the phenyl rings significantly enhance the antioxidant activities of these derivatives. The study also integrates global and local reactivity descriptors, such as Fukui functions and HOMO-LUMO energies, to predict the stability and reactivity of these molecules, providing insights into their potential as effective synthetic antioxidants in pharmaceutical applications. [ABSTRACT FROM AUTHOR]

Persistent radicals facilitate numerous selective radical coupling reactions. Here, we have identified acyl triazole as a new and versatile moiety for generating persistent radical intermediates through single-electron transfer processes. The efficient generation of these persistent radicals is facilitated by the formation of substrate-coordinated cobalt complexes, which subsequently engage in radical cross-coupling reactions. Remarkably, triazole-coordinated cobalt complexes exhibit metal-hydride hydrogen atom transfer (MHAT) capabilities with alkenes, enabling the efficient synthesis of diverse ketone products without the need for external ligands. By leveraging the persistent radical effect, this catalytic approach also allows for the development of other radical cross-coupling reactions with two representative radical precursors. The discovery of acyl triazoles as effective substrates for generating persistent radicals and as ligands for cobalt catalysis, combined with the bifunctional nature of the cobalt catalytic system, opens up new avenues for the design and development of efficient and sustainable organic transformations. Persistent radical-mediated cross-coupling has emerged as a powerful tool in organic synthesis for forging new C–C bonds. Here, the authors identify acyl triazoles as a versatile moiety for generating persistent radical intermediates through single-electron transfer processes, in the context of cobalt-catalysed carbon-carbon couplings under photoirradiation. [ABSTRACT FROM AUTHOR]

Site-selective C(sp3)–H arylation is an appealing strategy to synthesize complex arene structures but remains a challenge facing synthetic chemists. Here we report the use of photoredox-mediated hydrogen atom transfer (HAT) catalysis to accomplish the site-selective α-C(sp3)–H arylation of dialkylamine-derived ureas through 1,4-radical aryl migration, by which a wide array of benzylamine motifs can be incorporated to the medicinally relevant systems in the late-stage installation steps. In contrast to previous efforts, this C–H arylation protocol exhibits specific site-selectivity, proforming predominantly on sterically more-hindered secondary and tertiary α-amino carbon centers, while the C–H functionalization of sterically less-hindered N-methyl group can be effectively circumvented in most cases. Moreover, a diverse range of multi-substituted piperidine derivatives can be obtained with excellent diastereoselectivity. Mechanistic and computational studies demonstrate that the rate-determining step for methylene C–H arylation is the initial H atom abstraction, whereas the radical ipso cyclization step bears the highest energy barrier for N-methyl functionalization. The relatively lower activation free energies for secondary and tertiary α-amino C–H arylation compared with the functionalization of methylic C–H bond lead to the exceptional site-selectivity. Site-selective C(sp3)–H arylation is an appealing strategy to synthesize complex arene structures but remains a challenge facing synthetic chemists. Here the authors report the use of photoredox-mediated hydrogen atom transfer (HAT) catalysis to accomplish the site-selective α-C(sp3)–H arylation of dialkylamine-derived ureas through 1,4-radical aryl migration. [ABSTRACT FROM AUTHOR]

Plastic pollution constitutes an evergrowing urgent environmental problem, since overaccumulation of plastic waste, arising from the immense increase of the production of disposable plastic products, overcame planet's capacity to properly handle them. Chemical upcycling of polystyrene constitutes a convenient method for the conversion of plastic waste into high‐added value chemicals, suggesting an attractive perspective in dealing with the environmental crisis. We demonstrate herein a novel, easy‐to‐perform organocatalytic photoinduced aerobic protocol, which proceeds via synergistic indirect hydrogen atom transfer (HAT) catalysis under LED 390 nm Kessil lamps as the irradiation source. The developed method employs a BrCH2CN‐thioxanthone photocatalytic system and was successfully applied to a variety of everyday‐life plastic products, leading to the isolation of benzoic acid after simple base‐acid work up in yields varying from 23–49 %, while a large‐scale experiment was successfully performed, suggesting that the photocatalytic step is susceptible to industrial application. [ABSTRACT FROM AUTHOR]

Fluorine-containing saturated nitrogen heterocycles are very attractive structures in medicinal and biological chemistry because fluorine can be used to tune conformation as well as key properties such as basicity and bioavailability. At present cyclic fluorinated amines are accessed using hazardous reagents such as DAST or by lengthy synthesis routes. Here we report a modular two-step synthesis of cyclic β-fluoroalkyl amines using a photoredox-catalysed cyclisation/hydrogen atom transfer reaction of bromodifluoroethylamines. [ABSTRACT FROM AUTHOR]

This study focuses on the synthesis of H‐ and MeO‐ functionalized alkali metal hypersilyl borates. Consequently, two distinct silanides were used as polysilane frameworks for our chemical manipulations. Tris(silyl)silanide (1) and tris(trimethoxysilyl)silanide (2) react in the same manner with the BH3 ⋅ SMe2 complex to obtain two new alkali metal hypersilyl borates [(R3Si)3SiBH3M (M=alkali metal; R=H, (3), R=MeO, (4 a–c))] in good to excellent yields. NMR spectroscopy for all compounds and single‐crystal X‐ray crystallography for 3 and 4 a, b enabled a clear structural characterization. Single crystal X‐ray analysis of 3 showed a dimeric structure, where two THF‐molecules and three hydrides from the BH3‐group contribute to the coordination sphere of the lithium atom. Interestingly, crystals suitable for X‐ray analysis of 4 a and 4 b showed a solvent‐free cluster formation, due to the coordination of the MeO groups. Both species form coordination polymers with different coordination modes depending on the nature of the alkali metal. Attempted hydride abstraction reactions of 3 and 4 with various reagents under the formation of the free boranes proceeded unselectively. [ABSTRACT FROM AUTHOR]

Synthetic radicals have intrinsic power for cascading and multifunctional reactions to construct diverse molecular scaffolds. In the previous review series, we covered 1,2-difunctionalizations, remote 1,3-, 1,4-, 1,5-, 1,6-, and 1,7-difunctionalizations, addition followed by cyclization reactions, and cycloaddition-initiated difunctionalizations. Presented in this paper are radical addition-initiated trifunctionalization reactions of alkenes, alkynes, and their derivatives. After the initial radical addition, there are different pathways, such as group or hydrogen atom transfer, cyclization, and radical coupling, to complete the second and third functionalizations. [ABSTRACT FROM AUTHOR]

As part of a series of studies of hydrogen‐atom transfer or tautomerization reactions of imidic acid–amide species, H─O═C─N─⇌O═C─N─H${\rm H\bond O\dbond C\bond N\bond} \rightleftharpoons {\rm O\dbond C\bond N\bond H}$, we report the rate constants for a set of 24 five‐membered cyclic compounds at low, 50–300 K, and high, 500–1500 K, temperatures. These rate constants are for both the high temperature direct reaction and for that mediated by an additional water molecule which facilitates the hydrogen transfer reaction at low temperatures. In the latter case we show that the rate of reaction from a pre‐reaction complex can be rapid at temperatures down to 50 K on a 1 ms timescale and is dominated by quantum mechanical effects as evaluated by small‐curvature and quantised‐reaction‐states tunnelling. In addition, we present thermochemical data such as enthalpies of formation, entropies, isobaric heat capacities and enthalpy functions for these largely unknown species which span a range of compounds from pyrolidinone to oxo‐tetrazoles. [ABSTRACT FROM AUTHOR]

This study examined the antiradical activity of three synthesized coumarin derivatives: (E)-3-(1-((2-hydroxyphenyl)amino)ethylidene)-2,4-dioxochroman-7-yl acetate (A1-OH), (E)-3-(1-((3-hydroxyphenyl)amino)ethylidene)-2,4-dioxochroman-7-yl acetate (A2-OH), and (E)-3-(1-((4-hydroxyphenyl)amino)ethylidene)-2,4-dioxochroman-7-yl acetate (A3-OH) against HOO•/O2•− radical species. The investigation included electron spin resonance (ESR) measurements and a DFT kinetic study. Thermodynamic and kinetic parameters of antiradical mechanisms—Formal Hydrogen Atom Transfer (f-HAT), Radical Adduct Formation (RAF), Sequential Proton Loss followed by Electron Transfer (SPLET), and Single-Electron Transfer followed by Proton Transfer (SET-PT)—were evaluated using the Quantum Mechanics-based test for Overall Free Radical Scavenging Activity (QM–ORSA) under physiological conditions. ESR results indicated antiradical activity decreased in the sequence A1–OH (58.7%) > A2–OH (57.5%) > A3–OH (53.1%). Kinetic analysis revealed the f-HAT mechanism dominated HOO• inactivation. A newly formulated Sequential Proton Loss followed by Radical Adduct Formation (SPL-RAF) mechanism described interactions with O2•−. The activity toward O2•− was A2–OH (1.26 × 106 M−1s−1) > A3–OH (7.71 × 105 M−1s−1) > A1–OH (4.22 × 105 M−1s−1). Molecular docking and dynamics studies tested inhibitory capability against enzymes producing reactive species: Lipoxygenase (LOX), Myeloperoxidase (MPO), NAD(P)H oxidase (NOX), and Xanthine Oxidase (XOD). Affinity to enzymes decreased in the order: XOD > LOX > NOX > MPO. [ABSTRACT FROM AUTHOR]

A novel Fe-MoOx nanozyme, engineered with enhanced peroxidase (POD)-like activity through strategic doping and the creation of oxygen vacancies, is introduced to catalyze the oxidation of TMB with high efficiency. Furthermore, Fe-MoOx is responsive to single electron transfer (SET) and hydrogen atom transfer (HAT) mechanisms related to antioxidants and can serve as a desirable nanozyme for total antioxidant capacity (TAC) determination. The TAC colorimetric platform can reach a low LOD of 0.512 μM in solution and 24.316 μM in the smartphone-mediated RGB hydrogel (AA as the standard). As proof of concept, the practical application in real samples was explored. The work paves a promising avenue to design diverse nanozymes for visual on-site inspection of food quality. [ABSTRACT FROM AUTHOR]

Isatin-derived Schiff bases are the subject of many studies, finding wide application areas in polymer technology, pharmaceutical industry, and medicine. In this study, a series of new Schiff bases were prepared from monothiocarbohydrazones based on isatins with different substituents (5-F, 5-Br, 5-I, and 5-MeO). The chemical structures of the synthesized compounds were determined using 1H NMR, 13C NMR, FTIR spectroscopic techniques, and elemental analysis. Antioxidant activity determinations of 23 compounds were performed using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical quenching method. The highest percent inhibition value at 10 µM concentration was shown by compound number 22, 5-bromoisatin Schiff base containing 3-methoxy-4-hydroxy group. Compound 17, a 5-iodoisatin Schiff base containing 3-methoxy-4-hydroxy group, showed the highest antioxidant activity with an IC50 value of 9.76 ± 0.03 µM. In addition to the theoretical analysis of the compounds, both their spectroscopic and antioxidant properties were investigated. The ground-state geometries and some chemical reactivity parameters of the compounds were calculated using the B3LYP/6-311 + + G(2d,2p) approach. Besides intramolecular interactions, substituent effects, and some QTAIM parameters, the calculations were also performed to study the electronic properties of reactive N/O–H bonds and were used to interpret the experimental results. The effects of the electronic parameters and intramolecular interactions of reactive N/O–H bonds on the antioxidant properties of the compounds were investigated. Additionally, the relationships of DPPH reactions with delocalization indices of N/O-H bonds and the pattern of SET/HAT mechanisms with electronic variables were analyzed. Examination of electron and hydrogen atom transfer mechanisms has shown the dominance of electron transfer, supported by the correlation coefficients between IC50 values and SET reaction energies. [ABSTRACT FROM AUTHOR]

Context: Carbonyl compounds, especially aldehydes, emitted to the atmosphere, may suffer hydration in aerosols or water droplets in clouds. At the same time, they can react with hydroxyl radicals which may add or abstract hydrogen atoms from these species. The interplay between hydration and hydrogen abstraction is studied using density functional and quantum composite theoretical methods, both in the gas phase and in simulated bulk water. The H-abstraction from the aldehydic and geminal diol forms of formaldehyde, acetaldehyde, glycolaldehyde, glyoxal, methylglyoxal, and acrolein is studied to determine whether the substituent has any noticeable effect in the preference for the abstraction of one form or another. It is found that abstraction of the H-atom adjacent to the carbonyl group gives a more stable radical than same abstraction from the geminal diol in the case of formaldehyde, acetaldehyde, and glycolaldehyde. The presence of a delocalizing group in the Cα (a carbonyl group in glyoxal and methylglyoxal, and a vinyl group in acrolein), reverts this trend, and now the abstraction of the H-atom from the geminal diol gives more stable radicals. A further study was conducted abstracting hydrogen atoms from the other different positions in the species considered, both in the aldehydic and geminal diol forms. Only in the case of glycolaldehyde, the radical formed by H-abstraction from the –CH2OH group is more stable than any of the other radical species. Abstraction of the hydrogen atom in one of the hydroxyl groups in the geminal diol is equivalent to the addition of the •OH radical to the aldehyde. It leads, in some cases, to decomposition into a smaller radical and a neutral molecule. In these cases, some interesting theoretical differences are observed between the results in gas phase and (simulated) bulk solvent, as well as with respect to the method of calculation chosen. Methods: DFT (M06-2X, B2PLYP, PW6B95), CCSD(T), and composite (CBS-QB3, jun-ChS, SCVECV-f12) methods using Dunning basis sets and extrapolation to the CBS limit were used to study the energetics of closed shell aldehydes in their keto and geminal-diol forms, as well as the radical derived from them by hydrogen abstraction. Both gas phase and simulated bulk solvent calculations were performed, in the last case using the Polarizable Continuum Model. [ABSTRACT FROM AUTHOR]

In the present research, the physicochemical properties including electronic and structural properties and antioxidant activity of six fluorinated flavone derivatives have been discussed using of density functional theory calculations. Benchmarking studies of the DFT-B3LYP/6–311 + G(d, p) computational method were done using experimental 1HNMR and 13CNMR data of flavones 2 and 5. The experimental and calculated spectral data are in very good agreement with R2 < 92%. Using the DFT-B3LYP/6–311 + G(d, p) method, bond lengths and bond angles, intramolecular hydrogen interactions, EHOMO and ELUMO, electrophilicity index, and reactivity against active oxygen radicals were investigated. The local electrophilicity indices were calculated for flavones 1–6. Three reactive centers can be considered for nucleophilic attack on flavones 1–6. The data showed that the most active center is C9 on the 4-pyrone ring, conducting the Michael reaction, and the presence of -CF3 group on these compounds increases the electrophilic properties of flavones 1–6. Using three mechanisms of hydrogen atom transfer (HAT), single electron transfer followed by proton transfer (SET-PT), and the sequential proton loss electron transfer (SPLET) mechanisms, antioxidant activity of the studied flavones was investigated and compared with data for phenol. The presence of intramolecular hydrogen bonds strongly affects the antioxidant properties. According to the above-mentioned mechanisms, antioxidant activity of studied flavones 1–6 is higher than that of phenol. The presence of fluorine atom has a significant effect on their physicochemical properties. [ABSTRACT FROM AUTHOR]

It is imperative to have an in-depth understanding of the mechanism of action for the role of moisture in a coal matrix during coal spontaneous combustion, not only for preventing fires in the coal industry but also for reducing emissions of hazardous gases. In this study, the method of isotope tracing was first introduced to study the mechanism of moisture in the spontaneous combustion of coal. Moisture in a coal matrix was labeled separately using D2O and H218O, and the coal samples with internal moisture and external moisture were prepared by controlling the drying temperature. Coal samples with different isotopic moisture were heated using a spontaneous combustion apparatus. The gaseous products (CO2, CO, and CH4) were measured using a GC-950 gas chromatography equipped with a flame photometric detector, and simultaneously, the isotopic gases (including C18O, C18O2, CH3D) were timely monitored using an online mass spectrometer. The appearance of isotopic gases directly proved that the moisture could participate in the spontaneous combustion of coal in atomic level, and the moisture in the coal matrix is involved in the spontaneous combustion of coal through chemical reaction. Based on the experimental results, the pathways of the oxygen atom and H atom from the moisture participating in the production of isotopic gases were investigated. The reaction mechanism of moisture participating in the spontaneous combustion of coal was also explored based on the migration law of oxygen and hydrogen atoms of H2O molecule in coal matrix. [ABSTRACT FROM AUTHOR]

Light‐driven carboxylation offers a promising approach for synthesizing valuable fine chemicals under mild conditions. Here we disclose a heterogeneous photocatalytic strategy of C(sp2)−H activation of formate for hydrocarboxylation of alkenes over zinc indium sulfide (ZnIn2S4) under visible light. This protocol functions well with a variety of substituted styrenes with good to excellent yields; it also works for unactivated alkenes albeit with lower yields. Mechanistic studies confirm the existence of CO2⋅− as a key intermediate. It was found that C(sp2)−H activation of formate is induced by S⋅ species on the surface of ZnIn2S4 via hydrogen atom transfer (HAT) instead of a photogenerated hole oxidation mechanism. Moreover, both cleavage of the C(sp2)−H of HCOO− and formation of a benzylic anion were found to be involved in the rate‐determining step for the hydrocarboxylation of styrene. [ABSTRACT FROM AUTHOR]

\nHIGHLIGHTSAllium dictyoprasum C.A. Meyer ex Kunth (A. dictyoprasum) underwent comprehensive analysis, encompassing quantum chemical computations to assess its radical scavenging potential, chemical and elemental composition, total phenolic content, and antimicrobial activity. Experimental and theoretical investigations focused on elucidating the radical scavenging properties of polyhydroxy phenolic compounds present in the plant. Quantum chemical calculations were employed to evaluate the antioxidants employed to evaluate selected polyhydroxy phenolic molecules including flavonoids, hydrocinnamic acid derivatives, and hydroxybenzoic acid derivatives from natural sources. Thermochemical parameters of these compounds were calculated by the B3LYP/6–311 G++(d,p) level in both gas and solvent phases to elucidate the radical scavenging mechanism including hydrogen atom transfer (HAT), single electron transfer followed by proton transfer (SET-PT) and sequential proton loss electron transfer (SPLET). Analysis of A. dictyoprasum extracts obtained via various extraction methods revealed the presence of several major compounds, including dimethyl trisulfide, 3,5-Dihydroxy-6-methyl-2,3-dihydro-4 H-pyran-4-one, 2-Methoxy-4-vinylphenol, Dimethyl phthalate, Methyl palmitate, Methyl oleate, Methyl stearate, (9Z)-9-Octadecenamide. Notably, Malic acid and Quinic acid were identified as major compounds, with concentrations of 43.31 and 17.47 mg kg−1 extract, respectively, based on LC-MS/MS analysis. The total phenolic content of the extract was measured as 17.83 mg gallic acid/mL, while its free radical scavenging activity was 80.89% per mg/mL. Elemental analysis revealed significant levels of Mg, K, Na, Fe, and P, with minor concentrations of elements such as Ti, Tl, B, and Be. Furthermore, A. dictyoprasum exhibited notable antibacterial activity against various bacteria strains, surpassing the efficacy of some commercial antibiotics.Quantum chemical calculations of radical scavenging analysis were performed.Thermochemical parameters were calculated by the B3LYP/6–311 G++(d,p) level.Radical scavenging mechanism was evaluated based on HAT, SET-PT and SPLET.Chemical composition of Allium dictyoprasum C.A. Meyer ex Kunth was determined.A. dictyoprasum has a greater antibacterial effects than some commercial antibiotics. [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]

A series of zinc(II) thioamidate complexes [Zn{SC(iPr)NR}2]n for R = iPr (n = 2) (2), tBu (3) (n = 1), Ph (4) (n = 2) and Cy (5) (n = 2) and one cadmium(II) thioamidate complex [Cd{SC(iPr)NtBu}2]3, (6), were designed and synthesised as single-source precursors for AACVD ZnS and CdS. Solid-state structures of all four zinc(II) compounds revealed distorted tetrahedral or trigonal bipyramidal geometries, with varying tendencies for dimeric association, mediated by {Zn–S} bridging bonds. The thermogravimetric analysis identified the {tBu} derivertive, 3, as the most promising precursor based on its low decomposition onset (118 °C) and clean conversion to ZnS. This was attributed to the greater availability of β-hydrogen atoms promoting the pyrolysis mechanism. The corresponding cadmium thioamide 6 was found to crystallise as a trimetallic molecule which lacked the thermal stability to be considered viable for AACVD. Hence, 3 was used to deposit ZnS thin films by AACVD at 200–300 °C. Powder X-ray diffraction confirmed phase-pure growth of hexagonal wurtzite ZnS, with approximate crystallite sizes of 15–20 nm. Scanning electron microscopy revealed densely packed spherical nanoclusters. The morphology and crystallinity were most consistent for depositions between 250–300 °C. Energy dispersive X-ray spectroscopy indicated slightly sulfur-deficient stoichiometries. [ABSTRACT FROM AUTHOR]

The Cu−O−Cu core exhibits methane‐to‐methanol conversion, mirroring the reactivity of the copper–containing enzyme pMMO. Herein, we computationally examined the reactivity of a biomimetic Cu−O−Cu core towards methane–to–methanol conversion. The oxygen atom of the Cu−O−Cu core abstracts hydrogen present in the C−H bond of methane. The spin density at the bridging oxygen helps to abstract hydrogen from the C−H bond. We modulated the spin density of the bridging oxygen by substituting only a single copper atom of the Cu−O−Cu core by metals (M) such as Fe, Co, and Ag. These substitutions result in bimetallic [Cu−O−M]2+ models. We observed that the energy barriers for the C−H activation step and the subsequent rebound step vary with the metal M. [Cu−O−Ag]2+ exhibits the highest reactivity for M2M conversion, while [Cu−O−Fe]2+ displays the lowest reactivity. To understand the different reactivity of these models towards M2M conversion, we employed distortion‐interaction analysis, orbital analysis, spin density analysis, and quantum theory of atoms in molecules analysis. Orbital analysis reveals that all four adducts follow a hydrogen atom transfer mechanism for C−H activation. Further, spin density analysis reveals that a higher spin density on the bridging oxygen leads to a lower C−H activation barrier. [ABSTRACT FROM AUTHOR]

The metal-free porphyrins protonation has gained interest over five decades because its structure modification and hardly monoacid intermediate isolation. Here, upon the hydrogen atom abstraction processes, one step diproptonated H3STTP(BF4)2 (STTP = 5,10,15,20-tetraphenyl-21-thiaporphyrin) (3) and stepwise protonated HS2TTPSbCl6 (5) and diprotonated H2S2TTP(BF4)2 (6) (S2TTP = 5,10,15,20-tetraphenyl-21,23-thiaporphyrin) compounds were obtained using HSTTP and S2TTP with oxidants. The closed-shell protonated compounds were fully characterized using XRD, UV-vis, IR and NMR spectra. In addition, the reduced 19π compounds [K(2,2,2)]HSTTP (2) and [K(2,2,2)]S2TTP (7) were synthesized by the ligands with reductant KC8 in THF solution. These two open-shell compounds were characterized with UV-vis, IR and EPR spectroscopies. The semiempirical ZINDO/S method was employed to analyze the HOMO/LUMO gap lever and identify the electronic transitions of the UV-vis spectra of the closed- and open-shell porphyrin compounds. [ABSTRACT FROM AUTHOR]

This article explores the synthesis of α,β-unsaturated carbonyl compounds, which have applications in pharmacology and materials science. It discusses various methods for synthesizing these compounds, with a focus on the use of earth-abundant metals like iron and cobalt as catalysts. The authors explain the mechanisms involved in these reactions and highlight the advantages of using earth-abundant metals. While these methods have been used in the synthesis of pharmaceuticals and bioactive molecules, there are still challenges to overcome, and more research is needed to develop more efficient and environmentally friendly catalytic systems. [Extracted from the article]

Reaction of a rare and well‐characterized MnIII‐superoxo species, Mn(BDPBrP)(O2⋅) (1, H2BDPBrP=2,6‐bis((2‐(S)‐di(4‐bromo)phenylhydroxylmethyl‐1‐pyrrolidinyl)methyl)pyridine), with 4‐dimethylaminophenol at −80 °C proceeds via concerted proton electron transfer (CPET) to produce a MnIII‐hydroperoxo complex, Mn(BDPBrP)(OOH) (2), alongside 4‐dimethylaminophenoxy radical; whereas, upon treatment with 4‐nitrophenol, complex 1 undergoes a proton transfer process to afford a MnIV‐hydroperoxo complex, [Mn(BDPBrP)(OOH)]+ (3). Intriguingly, the reactions of 1 with 4‐chlorophenol and 4‐methoxyphenol follow two routes of CPET and sequential proton and electron transfer to furnish complex 2 in the end. UV‐vis and EPR spectroscopic studies coupled with DFT calculations provided support for this wide mechanistic spectrum of activating various phenol O−H bonds by a single MnIII‐superoxo complex, 1. [ABSTRACT FROM AUTHOR]

Methods enabling the broad diversification of C(sp3)−H bonds from a common intermediate are especially valuable in chemical synthesis. Herein, we report a site‐selective (N‐phenyltetrazole)thiolation of aliphatic and (hetero)benzylic C(sp3)−H bonds using a commercially available disulfide to access N‐phenyltetrazole thioethers. The thioether products are readily elaborated in diverse fragment couplings for C−C, C−O, or C−N construction. The C−H functionalization proceeds via a radical‐chain pathway involving hydrogen atom transfer by the electron‐poor N‐phenyltetrazolethiyl radical. Hexafluoroisopropanol was found to be essential to reactions involving aliphatic C(sp3)−H thiolation, with computational analysis consistent with dual hydrogen bonding of the N‐phenyltetrazolethiyl radical imparting increased radical electrophilicity to facilitate the hydrogen atom transfer. Substrate is limiting reagent in all cases, and the reaction displays an exceptional functional group tolerance well suited to applications in late‐stage diversification. [ABSTRACT FROM AUTHOR]

This study presents the phytochemical composition, antioxidant (hydrogen atom and single-atom transfer mechanisms), and digestive enzyme inhibitory (alpha-amylase, alpha-glucosidase, and pancreatic lipase) activities of ethanol-based extractions and traditional preparations (infusion) of the leaves of wild-edible Allium species (A. kharputense, A. affine, A. shirnakiense, and A. akaka) from the highlands of Eastern Anatolia. Among the eight extracts analyzed, ethanol extractions of the A. kharputense and A. akaka leaves exhibited better biotherapeutic activities and had the highest bioactive content. The dominant bioactive profile was composed of mainly allicin and phenolic compounds (chlorogenic acid, hesperidin, rutin, isoquercitrin, and quercetin) with small amounts of fatty acids. These data were similar to the biological activities and chemical composition of common Allium species and suggest the utilization of the extracts of wild-edible Allium species in the development of Allium-based biotherapeutics or nutraceuticals. [ABSTRACT FROM AUTHOR]