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Manganese (Mn) oxides are promising cathode materials for rechargeable aqueous Zn‐ion batteries. However, the Mn dissolution in weakly acidic electrolytes always hinders the development of better aqueous Zn–Mn batteries. Herein, a hydroxylated manganese oxide cathode material (H‐MnO2) is fabricated using an electrochemical method for stable aqueous Zn–Mn batteries without relying on the Mn2+ electrolyte additives. The partial hydroxylation of the oxides leads to charge redistribution of the material, changing the reaction thermodynamics and kinetics. Theoretical simulation suggests that the hydroxylation of manganese oxide promotes both Zn2+ adsorption thermodynamics and diffusion kinetics on the surface of H‐MnO2 but weakens the interaction between H+ and the electrode. Therefore, Zn2+ ions can be more reactive with the hydroxylated manganese oxide than H+ ions. Experimental results show that the Zn2+ insertion mechanism dominates the charge storage process of H‐MnO2, and the H+‐induced Mn dissolution reaction is effectively alleviated. Importantly, H‐MnO2 exhibits good cycling stability with 95% capacity retention over 5000 cycles at the current density of 3.8 A g−1 in the ZnSO4 electrolyte, outperforming the state‐of‐the‐art aqueous Zn–Mn batteries, even those with Mn2+ electrolyte additives. The findings provide new insights for designing stable manganese oxide cathodes in aqueous Zn–Mn batteries. [ABSTRACT FROM AUTHOR]

Hierarchically structured materials are considered to be one of the important options to enhance the mass transportation efficiency in microporous zeolites. Herein, we reported a highly efficient steam-assisted crystallization strategy for the synthesis of a hierarchical TS-1 zeolite with a tunable macropore size. The amorphous SiO2–TiO2 precursor dissolved gradually and acted as both a nutrient supplier and macropore template in situ. The framework Ti content of the synthesized TS-1 zeolites could be tuned over a wide range (Ti wt% = 0.70–1.39) by varying the Ti content of the SiO2–TiO2 precursor. Moreover, the pore size of the macropores could be modulated according to the particle size of the precursor based on the investigation of the formation mechanism of the macropores in the hierarchical TS-1 zeolite. The hierarchical TS-1 zeolite exhibited better catalytic activity in the epoxidation reaction of 1-hexene and hydroxylation of phenol compared to the typical microporous zeolites. The improved performance of the hierarchical TS-1 zeolite was probably caused by the improved diffusion performance of the hierarchical structure. [ABSTRACT FROM AUTHOR]

Propolis is a natural resinous compound produced by bees, mixed with their saliva and wax, and has a range of biological benefits, including antioxidant and anti-inflammatory effects. This article reviews the in vivo transformation of propolis flavonoids and their potential influence on drug efficacy. Despite propolis is widely used, there is little research on how the active ingredients of propolis change in the body and how they interact with drugs. Future research will focus on these interactions and the metabolic fate of propolis in vivo. [ABSTRACT FROM AUTHOR]

A substantial increase in colorectal cancer (CRC)–associated fatalities can be attributed to tumor recurrence and multidrug resistance. Traditional treatment options, including radio- and chemotherapy, also exhibit adverse side effects. Ancient treatment strategies that include phytochemicals like resveratrol are now widely encouraged as an alternative therapeutic option. Resveratrol is the natural polyphenolic stilbene in vegetables and fruits like grapes and apples. It inhibits CRC progression via targeting dysregulated cancer-promoting pathways, including PI3K/Akt/Kras, targeting transcription factors like NF-κB and STAT3, and an immunosuppressive tumor microenvironment. In addition, combination therapies for cancer include resveratrol as an adjuvant to decrease multidrug resistance that develops in CRC cells. The current review discusses the biology of resveratrol and explores different mechanisms of action of resveratrol in inhibiting CRC progression. Further, the detrimental role of resveratrol on the immunosuppressive tumor microenvironment of CRC has been discussed. This review illustrates clinical trials on resveratrol in different cancers, including resveratrol analogs, and their efficiency in promoting CRC inhibition. [ABSTRACT FROM AUTHOR]

SUMMARY: Erianin, crepidatin, and chrysotobibenzyl are typical medicinal polymethoxylated bibenzyls (PMBs) that are commercially produced in Dendrobium species. PMBs' chemo‐diversity is mediated by the manifold combinations of O‐methylation and hydroxylation in a definite order, which remains unsolved. To unequivocally elucidate the methylation mechanism of PMBs, 15 possible intermediates in the biosynthetic pathway of PMBs were chemically synthesized. DcOMT1–5 were highly expressed in tissues where PMBs were biosynthesized, and their expression patterns were well‐correlated with the accumulation profiles of PMBs. Moreover, cell‐free orthogonal tests based on the synthesized intermediates further confirmed that DcOMT1‐5 exhibited distinct substrate preferences and displayed hydroxyl‐group regiospecificity during the sequential methylation process. The stepwise methylation of PMBs was discovered from SAM to dihydro‐piceatannol (P) in the following order: P → 3‐MeP → 4‐OH‐3‐MeP → 4‐OH‐3,5‐diMeP → 3,3'(4′),5‐triMeP → 3,4,4′,5‐tetraMeP (erianin) or 3,3′,4,5‐tetraMeP (crepidatin) → 3,3′,4,4′,5‐pentaMeP (chrysotobibenzyl). Furthermore, the regioselectivities of DcOMTs were investigated by ligand docking analyses which corresponded precisely with the catalytic activities. In summary, the findings shed light on the sequential catalytic mechanisms of PMB biosynthesis and provide a comprehensive PMB biosynthetic network in D. catenatum. The knowledge gained from this study may also contribute to the development of plant‐based medicinal applications and the production of high‐value PMBs. [ABSTRACT FROM AUTHOR]

The enantioselective benzylic oxidation to synthesize chiral benzyl alcohols from alkylarenes poses a challenge. This study introduces a one-pot, two-step C–H bond hydroxylation process that integrates HRP-catalyzed oxidation and carbonyl reductase-catalyzed reduction for the enantiocomplementary synthesis of benzyl alcohols (up to 77% yield and 99% ee). This mild and operationally simple process provides an alternative approach to enantioselective benzylic hydroxylation. [ABSTRACT FROM AUTHOR]

Prolyl-hydroxylation is an oxygen-dependent posttranslational modification (PTM) that is known to regulate fibril formation of collagenous proteins and modulate cellular expression of hypoxia-inducible factor (HIF) α subunits. However, our understanding of this important but relatively rare PTM has remained incomplete due to the lack of biophysical methodologies that can directly measure multiple prolyl-hydroxylation events within intrinsically disordered proteins. Here, we describe a real-time 13C-direct detection NMR-based assay for studying the hydroxylation of two evolutionarily conserved prolines (P402 and P564) simultaneously in the intrinsically disordered oxygen-dependent degradation domain of hypoxic-inducible factor 1α by exploiting the "proton-less" nature of prolines. We show unambiguously that P564 is rapidly hydroxylated in a time-resolved manner while P402 hydroxylation lags significantly behind that of P564. The differential hydroxylation rate was negligibly influenced by the binding affinity to prolyl-hydroxylase enzyme, but rather by the surrounding amino acid composition, particularly the conserved tyrosine residue at the +1 position to P564. These findings support the unanticipated notion that the evolutionarily conserved P402 seemingly has a minimal impact in normal oxygen-sensing pathway. [ABSTRACT FROM AUTHOR]

Photocatalytic ozonation is considered to be a promising approach for the treatment of refractory organic pollutants, but the design of efficient catalyst remains a challenge. Surface modification provides a potential strategy to improve the activity of photocatalytic ozonation. In this work, density functional theory (DFT) calculations were first performed to check the interaction between O3 and TiO2−OH (surface hydroxylated TiO2) or TiO2−F (surface fluorinated TiO2), and the results suggest that TiO2−OH displays better O3 adsorption and activation than does TiO2−F, which is confirmed by experimental results. The surface hydroxyl groups greatly promote the O3 activation, which is beneficial for the generation of reactive oxygen species (ROS). Importantly, TiO2−OH displays better performance towards pollutants (such as berberine hydrochloride) removal than does TiO2−F and most reported ozonation photocatalysts. The total organic carbon (TOC) removal efficiency reaches 84.4 % within two hours. This work highlights the effect of surface hydroxylation on photocatalytic ozonation and provides ideas for the design of efficient photocatalytic ozonation catalysts. [ABSTRACT FROM AUTHOR]

Decarboxylative cross‐coupling reactions are powerful tools for carbon‐heteroatom bonds formation, but typically require pre‐activated carboxylic acids as substrates or heteroelectrophiles as functional groups. Herein, we present an electrochemical decarboxylative cross‐coupling of carboxylic acids with structurally diverse fluorine, alcohol, H2O, acid, and amine as nucleophiles. This strategy takes advantage of the ready availability of these building blocks from commercial libraries, as well as the mild and oxidant‐free conditions provided by electrochemical system. This reaction demonstrates good functional‐group tolerance and its utility in late‐stage functionalization. [ABSTRACT FROM AUTHOR]

The present study employed sodium hexametaphosphate (SHMP) as a depressant for quartz to achieve selective flotation separation of lepidolite. Micro-flotation and artificial mixed-mineral tests confirmed that the introduction of SHMP successfully facilitated the separation of lepidolite and quartz under weak acid conditions. The MD simulations revealed that hydroxylation of non-bridging oxygen atoms on the quartz surface influenced the adsorption of dodecylamine (DDA), while it had no impact on the adsorption of sodium hexametaphosphate (SHMP). Additionally, SHMP was found to form hydrogen bonds with hydroxyl groups present on the quartz surface, thereby enhancing its adsorption capacity and indirectly promoting a higher degree of surface hydroxylation to impede DDA adsorption, thus preserving the hydrophilic nature of the quartz surface. Conversely, the dissolution of K+ in the [Si6-nAlnO6] (n=0, 1, 2) rings on the lepidolite surface in an aqueous environment leads to a negative charge on lepidolite. This negatively charged state presents obstacles for SHMP adsorption onto the lepidolite surface; however, it facilitates strong attraction and firm adsorption of positively charged DDA within the ring cavities of lepidolite, resembling an "anchor". The adsorption test revealed that, following treatment with SHMP, a substantial amount of DDA remained adsorbed onto the lepidolite, while only a negligible quantity was observed on the quartz surface. Consequently, the introduction of SHMP enables effective inhibition of quartz under conditions characterized by low hydroxylation levels on its surface (weak acid or neutral), thereby facilitating the production of high-quality lepidolite products. [ABSTRACT FROM AUTHOR]

Mycoparasite secondary metabolites control fungal infections or diseases in agriculture and human health. Among genes involved in synthesizing secondary metabolites, cytochrome P450 monooxygenases (CYPs/P450s) play a key role in synthesizing and attributing diversity to the secondary metabolites. Despite the importance of P450s, a comparative analysis of P450s in mycoparasites has yet to be reported. This study is aimed at addressing this research gap. Genome-wide analysis of P450s in 43 fungi representing six fungal phyla and three distinct lifestyles, such as mycoparasitic (24 species), saprophytic (5 species), and ectomycorrhizal (14 species), revealed the expansion of P450s in Pezizomycete mycoparasites for the synthesis of secondary metabolites. The number of P450s and their families and subfamilies, the number of secondary-metabolite biosynthetic gene clusters (SMBGCs), and the number of P450s that are part of these SMBGCs were found to be highest in Pezizomycete mycoparasites compared to their counterparts of saprophytes and ectomycorrhiza, indicating P450s also play a key role in mycoparasitism. An analysis of P450 location as part of SMBGCs and the available literature on Pezizomycete P450s revealed that P450s play a key role in the synthesis of anti-fungal secondary metabolites such as trichothecene sesquiterpene, harzianum A, heptelidic acid, and gliotoxin. The mycoparasite Trichoderma virens Tv29.8 P450 CYP68Q3 is found to be a bifunctional enzyme with epoxidation and oxidation capability, and CYP5117A3 performs a Baeyer–Villiger oxidation reaction with regioselectivity. This study serves as a reference for future annotation of P450s in mycoparasites. [ABSTRACT FROM AUTHOR]

Published data on salicylic acid synthesis methods based on the use of phenol, ortho-cresol, and benzoic acid are reviewed and analyzed. Current trends in the development of a technology based on the Kolbe–Schmitt process (production of aromatic and heteroaromatic hydroxy acids by treating alkali metal phenolates with CO2) are shown. Data on the effect of the catalyst system composition and benzoic acid hydroxylation process conditions on the achieved conversion and selectivity values and purity of the product are described. The review can be useful for choosing a suitable raw material base and a precursor conversion method for the development of domestic production of salicylic acid, which is a high-demand compound used in various industries. [ABSTRACT FROM AUTHOR]

Microbial biotransformation of argentatin A (1), isoargentatin A (2) and argentatin B (3), the cycloartane- and lanostane-type triterpenoid constituents of guayule (Parthenium argentatum) resin, with Cunninghamella elegans ATCC 9245-A0 afforded eight new metabolites 4–11. These were identified as products formed as a result of: (i) α- and β-hydroxylation at C-7 and C-11; (ii) sequential oxidation of these newly formed alcohols to their corresponding carbonyl analogues; and (iii) rearrangement of the 9(10)-cyclopropane ring. The observed regiospecific hydroxylation reactions are possibly catalyzed by cytochrome P450 enzymes known to be produced by C. elegans. It is interesting that among the biotransformation products 9–11 of argentatin B (3) with a carbonyl group at C-11, only 11 had resulted from the rearrangement of the 9(10)-cyclopropane ring under the conditions used for biotransformation. This constitutes the first report of biotransformation of argentatins by C. elegans. [ABSTRACT FROM AUTHOR]

Iodosilarene derivatives (PhIO, PhI(OAc)2) constitute an important class of oxygen atom transfer reagents in organic synthesis and are often used together with iron-based catalysts. Since the factors controlling the ability of iron centers to catalyze alkane hydroxylation are not yet fully understood, the aim of this report is to develop bioinspired non-heme iron catalysts in combination with PhI(OAc)2, which are suitable for performing C-H activation. Overall, this study provides insight into the iron-based ([FeII(PBI)3(CF3SO3)2] (1), where PBI = 2-(2-pyridyl)benzimidazole) catalytic and stoichiometric hydroxylation of triphenylmethane using PhI(OAc)2, highlighting the importance of reaction conditions including the effect of the co-ligands (para-substituted pyridines) and oxidants (para-substituted iodosylbenzene diacetates) on product yields and reaction kinetics. A number of mechanistic studies have been carried out on the mechanism of triphenylmethane hydroxylation, including C-H activation, supporting the reactive intermediate, and investigating the effects of equatorial co-ligands and coordinated oxidants. Strong evidence for the electrophilic nature of the reaction was observed based on competitive experiments, which included a Hammett correlation between the relative reaction rate (logkrel) and the σp (4R-Py and 4R'-PhI(OAc)2) parameters in both stoichiometric (ρ = +0.87 and +0.92) and catalytic (ρ = +0.97 and +0.77) reactions. The presence of [(PBI)2(4R-Py)FeIIIOIPh-4R']3+ intermediates, as well as the effect of co-ligands and coordinated oxidants, was supported by their spectral (UV–visible) and redox properties. It has been proven that the electrophilic nature of iron(III)-iodozilarene complexes is crucial in the oxidation reaction of triphenylmethane. The hydroxylation rates showed a linear correlation with the FeIII/FeII redox potentials (in the range of −350 mV and −524 mV), which suggests that the Lewis acidity and redox properties of the metal centers greatly influence the reactivity of the reactive intermediates. [ABSTRACT FROM AUTHOR]

Demonstrated here is an external photo‐sensitizer‐free (auto‐sensitized) singlet oxygen‐enabled solvent‐dependent tertiary hydroxylation and aryl‐alkyl spiro‐etherification of C3‐maleimidated quinoxalines. Such "reagent‐less" photo‐oxygenation at Csp3‐H and etherification involving Csp3‐H/Csp2‐H are unparalleled. Possibly, the highly π‐conjugated N‐H tautomer allows the substrate to get excited by irradiation, and subsequently, it attains the triplet state via ISC. This excited triplet‐state sensitized molecule then transfers its energy to a triplet‐state oxygen (3O2) generating reactive singlet oxygen (1O2) for hydroxylation and spirocyclization depending on the solvent used. In HFIP, the generated alkoxy radical accepts a proton via HAT giving hydroxylated product. In contrast, in an aprotic PhCl it underwent a radical addition at the ortho‐position of the C2 aryl to provide spiro‐ether. An unprecedented orthogonal spiro‐etherification was observed via the displacement of o‐substitutents for ortho (−OEt, −OMe, −F, −Cl, −Br) substituted substrates. The order of ipso substitution follows the trend −OMe>−OEt>−F>−H>−Cl>−Br. Both these oxygenation reactions can be carried out with nearly equal ease using direct sunlight without the requirement of any elaborate reaction setup. Demonstration of large‐scale synthesis and a few interesting transformations have also been realized. Furthermore, several insightful control experiments and quantum chemical computations were performed to unravel the mechanism. [ABSTRACT FROM AUTHOR]

Herein, we report a general copper‐catalyzed method for the tunable oxygenative rearrangement of tetrahydrocarbazoles to cyclopentyl‐bearing spiroindolin‐2‐ones and spiroindolin‐3‐ones. The method demonstrates excellent chemoselectivity, regioselectivity, and product control simply by using the H2O and O2 as oxygen source, respectively. This open‐flask method is safe and simple to operate, and no other chemical oxidants are required. Besides, inspired from the unique pathway of 1, 2‐migration rearrangement, a highly controllable hydroxylation of indoles for the construction of C3a‐hydroxyl iminium indolines was also developed. Mechanistic experiments suggest that a single‐electron transfer‐induced oxidation process is responsible for the tunable selectivity control. [ABSTRACT FROM AUTHOR]

The hydroxylation of remote C(sp3)−H bonds in aliphatic amino acids yields crucial precursors for the synthesis of high‐value compounds. However, accurate regulation of the regioselectivity of remote C(sp3)−H bonds hydroxylation in aliphatic amino acids continues to be a common challenge in chemosynthesis and biosynthesis. In this study, the Fe(II)/α‐ketoglutarate‐dependent dioxygenase from Bacillus subtilis (BlAH) was mined and found to catalyze hydroxylation at the γ and δ sites of aliphatic amino acids. Crystal structure analysis, molecular dynamics simulations, and quantum chemical calculations revealed that regioselectivity was regulated by the spatial effect of BlAH. Based on these results, the spatial effect of BlAH was reconstructed to stabilize the transition state at the δ site of aliphatic amino acids, thereby successfully reversing the γ site regioselectivity to the δ site. For example, the regioselectivity of L‐Homoleucine (5 a) was reversed from the γ site (1 : 12) to the δ site (>99 : 1). The present study not only expands the toolbox of biocatalysts for the regioselective functionalization of remote C(sp3)−H bonds, but also provides a theoretical guidance for the precision‐driven modification of similarly remote C(sp3)−H bonds in complex molecules. [ABSTRACT FROM AUTHOR]

The peroxygenases are ideal biocatalysts for the selective oxyfunctionalisation of stable C-H bonds. However, the catalytic efficiency of this approach is limited due to enzyme lability toward oxidant H2O2. Although the reported in-situ H2O2 generation system enables the stable biocatalytic process without deactivating the enzyme, the greatest catalytic potential of peroxygenases still cannot be fulfilled effectively. To address the above issue, a H2O2 generation-detection-regulation platform that integrated an effective organocatalyst-driven H2O2 generation system, a precise electrochemical H2O2 real-time detection device, and a convenient H2O2 regulation strategy was first developed. The suitable range of H2O2 generation rate for maximizing the catalytic efficiency of perox-ygenases while minimizing inactivation of the enzyme was firstly obtained by simply adjusting the amount of organocatalyst. According to the determined suitable range, the C-H oxyfunctionalisation efficiency of peroxygenases for each substrate was significantly boosted, achieving ~3-fold of the reported highest turnover frequency. [ABSTRACT FROM AUTHOR]

Background: Polysaccharide from Garcinia mangostana rind has many biological activities and deserves further research. Methods: The antioxidant properties of UAEE-GMRP, UAEE-GMRP-1 A, CM-30, and Ac-30 were evaluated through two different antioxidant activity experimental systems. Results: The four polysaccharides had a better scavenging effect on hydroxyl radicals, while their inhibitory effect on lipid peroxidation was relatively weak. However, overall, the four polysaccharides showed a certain degree of potential application in the two antioxidant experiments mentioned above, especially the chemically modified polysaccharides from Garcinia mangostana rind, which effectively improved their antioxidant activity. This also indicates that chemical modification is a better method to improve polysaccharide activity. In addition, in these two antioxidant exploration experiments, carboxymethylated polysaccharide showed stronger activity compared to the other three polysaccharides. Conclusion: The carboxymethylation modification may have great potential for application. [ABSTRACT FROM AUTHOR]

Major constituents of the plant cell walls are structural proteins that belong to the hydroxyproline-rich glycoprotein (HRGP) family. Leucine-rich repeat extensin (LRX) proteins contain a leucine-rich domain and a C-terminal domain with repetitive Ser–Pro3–5 motifs that are potentially to be O -glycosylated. It has been demonstrated that pollen-specific LRX8–LRX11 from Arabidopsis thaliana are necessary to maintain the integrity of the pollen tube cell wall during polarized growth. In HRGPs, including classical extensins (EXTs), and probably in LRXs, proline residues are converted to hydroxyproline by prolyl-4-hydroxylases (P4Hs), thus defining novel O -glycosylation sites. In this context, we aimed to determine whether hydroxylation and subsequent O -glycosylation of Arabidopsis pollen LRXs are necessary for their proper function and cell wall localization in pollen tubes. We hypothesized that pollen-expressed P4H4 and P4H6 catalyze the hydroxylation of the proline units present in Ser–Pro3–5 motifs of LRX8–LRX11. Here, we show that the p4h4-1 p4h6-1 double mutant exhibits a reduction in pollen germination rates and a slight reduction in pollen tube length. Pollen germination is also inhibited by P4H inhibitors, suggesting that prolyl hydroxylation is required for pollen tube development. Plants expressing pLRX11::LRX11-GFP in the p4h4-1 p4h6-1 background show partial re-localization of LRX11–green fluorescent protein (GFP) from the pollen tube tip apoplast to the cytoplasm. Finally, immunoprecipitation-tandem mass spectrometry analysis revealed a decrease in oxidized prolines (hydroxyprolines) in LRX11–GFP in the p4h4-1 p4h6-1 background compared with lrx11 plants expressing pLRX11::LRX11-GFP. Taken together, these results suggest that P4H4 and P4H6 are required for pollen germination and for proper hydroxylation of LRX11 necessary for its localization in the cell wall of pollen tubes. [ABSTRACT FROM AUTHOR]

The tert‐butyl group is a common aliphatic motif extensively employed to implement steric congestion and conformational rigidity in organic and organometallic molecules. Because of the combination of a high bond dissociation energy (~100 kcal mol−1) and limited accessibility, in the absence of directing groups, neither radical nor organometallic approaches are effective for the chemical modification of tert‐butyl C−H bonds. Herein we overcome these limits by employing a highly electrophilic manganese catalyst, [Mn(CF3bpeb)(OTf)2], that operates in the strong hydrogen bond donor solvent nonafluoro‐tert‐butyl alcohol (NFTBA) and catalytically activates hydrogen peroxide to generate a powerful manganese‐oxo species that effectively oxidizes tert‐butyl C−H bonds. Leveraging on the interplay of steric, electronic, medium and torsional effects, site‐selective and product chemoselective hydroxylation of the tert‐butyl group is accomplished with broad reaction scope, delivering primary alcohols as largely dominant products in preparative yields. Late‐stage hydroxylation at tert‐butyl sites is demonstrated on 6 densely functionalized molecules of pharmaceutical interest. This work uncovers a novel disconnection approach, harnessing tert‐butyl as a potential functional group in strategic synthetic planning for complex molecular architectures. [ABSTRACT FROM AUTHOR]

The tert‐butyl group is a common aliphatic motif extensively employed to implement steric congestion and conformational rigidity in organic and organometallic molecules. Because of the combination of a high bond dissociation energy (~100 kcal mol−1) and limited accessibility, in the absence of directing groups, neither radical nor organometallic approaches are effective for the chemical modification of tert‐butyl C−H bonds. Herein we overcome these limits by employing a highly electrophilic manganese catalyst, [Mn(CF3bpeb)(OTf)2], that operates in the strong hydrogen bond donor solvent nonafluoro‐tert‐butyl alcohol (NFTBA) and catalytically activates hydrogen peroxide to generate a powerful manganese‐oxo species that effectively oxidizes tert‐butyl C−H bonds. Leveraging on the interplay of steric, electronic, medium and torsional effects, site‐selective and product chemoselective hydroxylation of the tert‐butyl group is accomplished with broad reaction scope, delivering primary alcohols as largely dominant products in preparative yields. Late‐stage hydroxylation at tert‐butyl sites is demonstrated on 6 densely functionalized molecules of pharmaceutical interest. This work uncovers a novel disconnection approach, harnessing tert‐butyl as a potential functional group in strategic synthetic planning for complex molecular architectures. [ABSTRACT FROM AUTHOR]

Regioselective and enantioselective hydroxylation of propargylic C-H bonds are useful reactions but often lack appropriate catalysts. Here a green and efficient asymmetric hydroxylation of primary and secondary C–H bonds at propargylic positions has been established. A series of optically active propargylic alcohols were prepared with high regio- and enantioselectivity (up to 99% ee) under mild reaction conditions by using P450tol, while the C≡C bonds in the molecule remained unreacted. This protocol provides a green and practical method for constructing enantiomerically chiral propargylic alcohols. In addition, we also demonstrated that the biohydroxylation strategy was able to scaled up to 2.25 mmol scale with the production of chiral propargyl alcohol 2a at a yield of 196 mg with 96% ee, which's an important synthetic intermediate of antifungal drug Ravuconazole. [ABSTRACT FROM AUTHOR]

Adding HClO4 to [(BnTPEN)MnIII–OO]+ in MeOH generates a short-lived MnIII–OOH species, which converts to a putative MnV＝O species. The potent MnV＝O species in MeCN oxidizes the pendant phenyl ring of the ligand in an intramolecular fashion. The addition of benzene causes the formation of (BnTPEN)MnIII-phenolate. These findings suggest that high valent Mn species have the potential to catalyze challenging aromatic hydroxylation reactions. [ABSTRACT FROM AUTHOR]

The aim of this study was to obtain new halolactones with a gem-dimethyl group in the cyclohexane ring (at the C-3 or C-5 carbon) and a methyl group in the lactone ring and then subject them to biotransformations using filamentous fungi. Halolactones in the form of mixtures of two diasteroisomers were subjected to screening biotransformations, which showed that only compounds with a gem-dimethyl group located at the C-5 carbon were transformed. Strains from the genus Fusarium carried out hydrolytic dehalogenation, while strains from the genus Absidia carried out hydroxylation of the C-7 carbon. Both substrates and biotransformation products were then tested for antimicrobial activity against multidrug-resistant strains of both bacteria and yeast-like fungi. The highest antifungal activity against C. dubliniensis and C. albicans strains was obtained for compound 5b, while antimicrobial activity against S. aureus MRSA was obtained for compound 4a. [ABSTRACT FROM AUTHOR]

The mechanism of the combined process of ion beam sputtering (IBS) and HF acid etching on the chemical structure defects of fused silica and its laser damage resistance performance were investigated in this paper. During the removal process of surface material, the sputtering effect causes lattice atoms to flee their native space locations, and a large amount of unsaturated chemical structures are produced on the silica surface, which improves the chemical activity of Si and O atoms, accelerates the chemical reaction process between surface atoms and water molecules, increases the content of hydroxyl groups (OH-) in the shallow layer, and enhances the photothermal weak absorption intensity. However, the increase in hydroxyl content weakens the binding strength of silicon–oxygen bonds, destroys the spatial network structure of silica bulk, and reduces its mechanical strength, resulting in a decrease in its laser damage resistance performance. The paper reveals for the first time the mechanism by which IBS changes the structure characteristics of silica material, accelerates the surface hydroxylation process, and thereby reduces the laser damage resistance performance. This work provides technical guidance for effectively suppressing chemical structure defects on silica surfaces and improving the laser damage resistance performance of optical components under high-flux laser irradiation. [ABSTRACT FROM AUTHOR]

A phytoalexin polyphenolic chemical, resveratrol, can be found in a variety of foods, including cereals, peanuts, grapes, strawberries, and raspberries. It is also known that resveratrol protects the body against cardiovascular diseases as well as various types of cancer. In addition to these health issues, resveratrol is currently the subject of research since it helps treat and prevent a number of illnesses. More clinical research is needed to validate resveratrol's potential as a therapeutic agent, despite the plethora of in vitro and in vivo evidence to support this. When the literature data are evaluated, the fact that resveratrol has a therapeutic effect in these studies, but it is known to be subject to rapid metabolism despite its low bioavailability and oral absorption of approximately 75%, has directed the studies to resveratrol derivatives, especially piceatannol. Based on recent studies, 4 types of resveratrol derivatives were assessed in this work: hydroxylated compounds, methoxylated compounds, glycosides, and oligomers. Because of their advantageous bioactivities, methoxylated, hydroxylated, and halogenated derivatives have drawn the most interest among these classes. However, as a result of these studies, more studies should be conducted to better understand whether resveratrol derivatives can be recommended as therapeutic agents. [ABSTRACT FROM AUTHOR]

Zastaprazan (JP-1366), a novel potassium-competitive acid blocker, is a new drug for the treatment of erosive esophagitis. JP-1366 is highly metabolized in human, mouse, and dog hepatocytes but moderately metabolized in rat and monkey hepatocytes when estimated from the metabolic stability of this compound in hepatocyte suspension and when 18 phase I metabolites and 5 phase II metabolites [i.e., N-dearylation (M6), hydroxylation (M1, M19, M21), dihydroxylation (M7, M8, M14, M22), trihydroxylation (M13, M18), hydroxylation and reduction (M20), dihydroxylation and reduction (M9, M16), hydrolysis (M23), hydroxylation and glucuronidation (M11, M15), hydroxylation and sulfation (M17), dihydroxylation and sulfation (M10, M12), N-dearylation and hydroxylation (M3, M4), N-dearylation and dihydroxylation (M5), and N-dearylation and trihydroxylation (M2)] were identified from JP-1366 incubation with the hepatocytes from humans, mice, rats, dogs, and monkeys. Based on the cytochrome P450 (CYP) screening test and immune-inhibition analysis with CYP antibodies, CYP3A4 and CYP3A5 played major roles in the metabolism of JP-1366 to M1, M3, M4, M6, M8, M9, M13, M14, M16, M18, M19, M21, and M22. CYP1A2, 2C8, 2C9, 2C19, and 2D6 played minor roles in the metabolism of JP-1366. UDP-glucuronosyltransferase (UGT) 2B7 and UGT2B17 were responsible for the glucuronidation of M1 to M15. However, JP-1366 and active metabolite M1 were not substrates for drug transporters such as organic cation transporter (OCT) 1/2, organic anion transporter (OAT) 1/3, organic anion transporting polypeptide (OATP)1B1/1B3, multidrug and toxic compound extrusion (MATE)1/2K, P-glycoprotein (P-gp), and breast cancer-resistant protein (BCRP). Only M1 showed substrate specificity for P-gp. The findings indicated that drug-metabolizing enzymes, particularly CYP3A4/3A5, may have a significant role in determining the pharmacokinetics of zastaprazan while drug transporters may only have a small impact on the absorption, distribution, and excretion of this compound. [ABSTRACT FROM AUTHOR]

With a rising demand of cocaine over the last years, it is likely that unregulated new psychoactive substances with similar effects such as indatraline ((1R,3S)-3-(3,4-dichlorophenyl)-N-methyl-2,3-dihydro-1H-inden-1-amine) and troparil (Methyl (1R,2S,3S,5S)-8-methyl-3-phenyl-8-azabicyclo[3.2.1]octane-2-carboxylate) become popular as well. Both substances share a similar pharmacological profile as cocaine, while their potency is higher, and their duration of action is longer. This study investigated their metabolic fate in rat urine and incubations using pooled human liver S9 fraction (pHLS9). Indatraline formed two phase I and four phase II metabolites, with aromatic hydroxylation and glucuronidation being the main metabolic steps. All metabolites were detected in rat urine, while the parent compound was not detectable. Although low in abundance, indatraline metabolites were well identifiable due to their specific isotopic patterns caused by chlorine. Troparil formed four phase I and three phase II metabolites, with demethylation being the main metabolic step. Hydroxylation of the tropane ring, the phenyl ring, and combinations of these steps, as well as glucuronidation, were found. Phase I metabolites were detectable in rat urine and pHLS9, while phase II metabolites were only detectable in rat urine. [ABSTRACT FROM AUTHOR]

Three types of smectite with various crystallochemical compositions and interlayer cations as well as kaolinite and illite were fired at 800°C and 650°C and tested for their rehydroxylation's (RHX) potential and kinetics in the presence of water vapor at 200°C–350°C. A dehydroxylated structure of 2:1 Al‐rich mineral with the interlayer pillared by a large cation (like K+ or Cs+) is wide enough to allow H2O diffusion which results in advanced RHX, that is, restoring up to several tens of percent of the original OH content. Such 2:1 layer structures (beidellite, illite) do not follow the time‐to‐the‐quarter (TTTQ) kinetics during RHX and show a non‐Arrhenius behavior for isothermal RHX. Because TTTQ kinetics is assumed in an RHX dating of ceramic artifacts in archaeometry, fired‐clay ceramics prepared from material dominated by Al‐rich 2:1 minerals was found unfeasible for RHX dating. Kaolinite and Mg2+‐ or Ca2+‐exchanged smectites show the Arrhenius behavior and follow the TTTQ kinetics of RHX, resulting in apparent Ea increase with the progress of reaction (up to α ∼0.2) of ∼20–50 kJ/mol in beidellite and 15–35 kJ/mol in montmorillonite. We suggest using 'hydroxylation' rather than 'rehydroxylation' for structurally‐disordered fired clays gaining OH groups in an unknown position. [ABSTRACT FROM AUTHOR]

Herein, a new method has been developed for the synthesis of various α‐hydroxyacetophenones via an electro‐oxidation process. It involves electrocatalytic hydroxylation via debromination of C(sp3)−Br bond. Here, simultaneous breaking of carbon‐bromine (C−Br) bond and formation of a new carbon‐oxygen (C−O) bond has been achieved through electrolysis of H2O using binary mixture of water and DMSO. The protocol features easy performance, oxidant and base‐free mild conditions and short reaction time. [ABSTRACT FROM AUTHOR]

A catalytic diastereoselective Prins reaction for hydroxymethylation and hydroxylation of 1,3-diarylpropene was successfully utilized to prepare various 1,3-dioxanes 7 in 14–88% yields. Take advantage of the synthetic intermediate 7h, the key B/C rings in brazilin core could be constructed by the sequential of Friedel–Crafts/Ullmann-Ma rather than Ullmann-Ma/Friedel–Crafts reactions. [ABSTRACT FROM AUTHOR]

Metal oxoclusters constitute a dynamic and expanding domain of research with versatile applications in catalysis, materials science, medicine, and beyond. Particular attention has been given to their potential utility due to their distinctive properties. The incorporation of ionic liquid (IL) environments into metal oxocluster (MOC) systems offers numerous advantages, including higher stability, tunable coordination to metal sites, and the capability to dissolve diverse substrates for catalytic applications. Although IL-stabilized MOCs (IL--MOCs) are still in the developmental phase, their potential to revolutionize catalysis is substantial. As research progresses, IL--MOCs will likely play an increasingly important role in catalysis. This perspective article focuses on the preparation methods of IL--MOCs, how the MOCs are stabilized/regulated by ILs or even PIL (polymeric ILs), as well as their catalytic applications, including oxidation, epoxidation, oxidative desulfurization, biomass oxidation, hydroxylation of benzene, acid catalysis, CO2 activation and utilization, carbonylation, hydrogenation/hydrolysis, electrochemistry, etc. IL--MOCs have played a crucial role in the development of sustainable chemistry in the light of the potential opportunities and challenges. The unique advantages make IL--MOCs outstanding candidates for industrial catalysts. [ABSTRACT FROM AUTHOR]

Key message: Mutants lacking functional HYD2 homoeologs showed improved seedling growth, but comparable or increased susceptibility to salt stress in tillering plants, suggesting a developmentally restricted role of HYD2 in salt response. Salinity stress threatens global food security by reducing the yield of staple crops such as wheat (Triticum ssp.). Understanding how wheat responds to salinity stress is crucial for developing climate resilient varieties. In this study, we examined the interplay between carotenoid metabolism and the response to salt (NaCl) stress, a specific form of salinity stress, in tetraploid wheat plants with mutations in carotenoid β-hydroxylase 1 (HYD1) and HYD2. Our investigation encompassed both the vulnerable seedling stage and the more developed tillering stage of wheat plant growth. Mutant combinations lacking functional HYD2 homoeologs, including hyd-A2 hyd-B2, hyd-A1 hyd-A2 hyd-B2, hyd-B1 hyd-A2 hyd-B2, and hyd-A1 hyd-B1 hyd-A2 hyd-B2, had longer first true leaves and slightly enhanced root growth during germination under salt stress compared to the segregate wild-type (control) plants. Interestingly, these mutant seedlings also showed decreased levels of neoxanthin and violaxanthin (xanthophylls derived from β-carotene) and an increase in β-carotene in roots. However, tillering hyd mutant and segregate wild-type plants generally did not differ in their height, tiller count, and biomass production under acute or prolonged salt stress, except for decreases in these parameters observed in the hyd-A1 hyd-B1 hyd-A2 hyd-B2 mutant that indicate its heightened susceptibility to salt stress. Taken together, these findings suggest a significant, yet developmentally restricted role of HYD2 homoeologs in salt-stress response in tetraploid wheat. They also show that hyd-A2 hyd-B2 mutant plants, previously demonstrated for possessing enriched nutritional (β-carotene) content, maintain an unimpaired ability to withstand salt stress. [ABSTRACT FROM AUTHOR]

Adherent bubbles at electrodes are generally treated as reaction penalties. Herein, in situ hydroxylation of indium tin oxide surfaces can be easily achieved by applying a constant potential of +1.0 V in the presence of bubbles. Its successful hydroxylation is further demonstrated by preparing a ferrocene-terminated film, which is confirmed by cyclic voltammetry and X-ray photoelectron spectroscopy. [ABSTRACT FROM AUTHOR]

The diversity and uniqueness of fungal cytochromes P450 (CYP), capable of catalyzing the regio- and stereospecific hydroxylation of steroids, makes them important for microbiological synthesis of valuable hydroxysteroids. In the present work, the function of recombinant fungal P450 monooxygenase (CYPI) of Curvularia sp. strain VKM F-3040, a promising biocatalyst of 7-hydroxylation of androstane steroids, was studied. RT-PCR amplification of cDNA of the candidate genes encoding CYPI and its natural redox partner (POR), their cloning and heterologous expression in the cells of E. coli BL 21 DE(3) was carried out. In vitro experiments showed the ability of the obtained recombinant monooxygenase to catalyze hydroxylation of dehydroepiandrosterone (DHEA) at positions 7α and 7β. Our results expand the knowledge about fungal steroid hydroxylases and open up the prospects for the synthesis of valuable 7-hydroxysteroids by using recombinant producers. [ABSTRACT FROM AUTHOR]

Unspecific peroxygenases (UPOs) are glycosylated enzymes that provide an efficient method for oxyfunctionalizing a variety of substrates using only hydrogen peroxide (H2O2) as the oxygen donor. However, their poor heterologous expression has hindered their practical application. Here, a novel UPO from Marasmius fiardii PR910 (MfiUPO) was identified and heterologously expressed in Pichia pastoris. By employing a two-copy expression cassette, the protein titer reached 1.18 g L−1 in a 5 L bioreactor, marking the highest record. The glycoprotein rMfiUPO exhibited a smeared band in the 40 to 55 kDa range and demonstrated hydroxylation, epoxidation and alcohol oxidation. Moreover, the peroxidative activity was enhanced by 150% after exposure to 50% (v/v) acetone for 40 h. A semi-preparative production of 4-OH-β-ionone on a 100 mL scale resulted in a 54.2% isolated yield with 95% purity. With its high expression level, rMfiUPO is a promising candidate as an excellent parental template for enhancing desirable traits such as increased stability and selectivity through directed evolution, thereby meeting the necessary criteria for practical application. [ABSTRACT FROM AUTHOR]

All biological hydroxylation reactions are thought to derive the oxygen atom from one of three inorganic oxygen donors, O2, H2O2 or H2O. Here, we have identified the organic compound prephenate as the oxygen donor for the three hydroxylation steps of the O2-independent biosynthetic pathway of ubiquinone, a widely distributed lipid coenzyme. Prephenate is an intermediate in the aromatic amino acid pathway and genetic experiments showed that it is essential for ubiquinone biosynthesis in Escherichia coli under anaerobic conditions. Metabolic labeling experiments with 18O-shikimate, a precursor of prephenate, demonstrated the incorporation of 18O atoms into ubiquinone. The role of specific iron--sulfur enzymes belonging to the widespread U32 protein family is discussed. Prephenate-dependent hydroxylation reactions represent a unique biochemical strategy for adaptation to anaerobic environments. [ABSTRACT FROM AUTHOR]

Saxitoxin (STX, 1) is a representative compound of paralytic shellfish toxins (PSTs) that are produced by marine dinoflagellates and freshwater cyanobacteria. Although several pathways have been proposed for the biosynthesis of STX, the order of ring and side chain hydroxylation, and formation of the tricyclic skeleton have not been well established. In this study, 12,12‐dideoxy‐decarbamoyloxySTX (dd‐doSTX, 2), the most reduced STX analogue having the tricyclic skeleton, and its analogues, 12β‐deoxy‐doSTX (12β‐d‐doSTX, 3), 12α‐deoxy‐doSTX (12α‐d‐doSTX, 4), and doSTX (5), were synthesized, and these compounds were screened in the toxic microalgae using high‐resolution LCMSMS. dd‐doSTX (2) and 12β‐d‐doSTX (3) were identified in the PSTs‐producing dinoflagellates (Alexandrium catenella, A. pacificum, and/or Gymnodinium catenatum) and in the cyanobacterium Dolichospermum circinale (TA04). doSTX (5), previously isolated from the dinoflagellate G. catenatum, was also identified in D. circinale (TA04). Furthermore, the conversion of 2 to 3, and 4 to 5, by SxtT with VanB, a reported Rieske oxygenase and its redox partner in STX biosynthesis, was confirmed. These results support that 2 is a possible biosynthetic precursor of STX, and that ring and side‐chain hydroxylations proceed after cyclization. [ABSTRACT FROM AUTHOR]

Biocatalytic oxidations are an emerging technology for selective C−H bond activation. While promising for a range of selective oxidations, practical use of enzymes catalyzing aerobic hydroxylation is presently limited by their substrate scope and stability under industrially relevant conditions. Here, we report the engineering and practical application of a non‐heme iron and α‐ketoglutarate‐dependent dioxygenase for the direct stereo‐ and regio‐selective hydroxylation of a non‐native fluoroindanone en route to the oncology treatment belzutifan, replacing a five‐step chemical synthesis with a direct enantioselective hydroxylation. Mechanistic studies indicated that formation of the desired product was limited by enzyme stability and product overoxidation, with these properties subsequently improved by directed evolution, yielding a biocatalyst capable of >15,000 total turnovers. Highlighting the industrial utility of this biocatalyst, the high‐yielding, green, and efficient oxidation was demonstrated at kilogram scale for the synthesis of belzutifan. [ABSTRACT FROM AUTHOR]

Biocatalytic oxidations are an emerging technology for selective C−H bond activation. While promising for a range of selective oxidations, practical use of enzymes catalyzing aerobic hydroxylation is presently limited by their substrate scope and stability under industrially relevant conditions. Here, we report the engineering and practical application of a non‐heme iron and α‐ketoglutarate‐dependent dioxygenase for the direct stereo‐ and regio‐selective hydroxylation of a non‐native fluoroindanone en route to the oncology treatment belzutifan, replacing a five‐step chemical synthesis with a direct enantioselective hydroxylation. Mechanistic studies indicated that formation of the desired product was limited by enzyme stability and product overoxidation, with these properties subsequently improved by directed evolution, yielding a biocatalyst capable of >15,000 total turnovers. Highlighting the industrial utility of this biocatalyst, the high‐yielding, green, and efficient oxidation was demonstrated at kilogram scale for the synthesis of belzutifan. [ABSTRACT FROM AUTHOR]

Inspired by the ubiquitous prevalence of 3‐hydroxyoxindoles in natural products and pharmaceuticals, we herein disclose a direct and practical transition‐metal‐free asymmetric hydroxylation using commercially available Davis enantiopure oxaziridines as efficient oxidants, expeditiously affording an array of medicinally active 3‐functionalized 3‐hydroxy‐2‐oxindoles bearing quaternary stereocenters. The protocol features cheap reactants, ease of operation, scalability, and good functional‐group tolerance and efficient formal synthesis of natural products. [ABSTRACT FROM AUTHOR]

The Von Hippel–Lindau (VHL) protein, which is frequently mutated in clear-cell renal cell carcinoma (ccRCC), is a master regulator of hypoxia-inducible factor (HIF) that is involved in oxidative stresses. However, whether VHL possesses HIF-independent tumor-suppressing activity remains largely unclear. Here, we demonstrate that VHL suppresses nutrient stress-induced autophagy, and its deficiency in sporadic ccRCC specimens is linked to substantially elevated levels of autophagy and correlates with poorer patient prognosis. Mechanistically, VHL directly binds to the autophagy regulator Beclin1, after its PHD1-mediated hydroxylation on Pro54. This binding inhibits the association of Beclin1-VPS34 complexes with ATG14L, thereby inhibiting autophagy initiation in response to nutrient deficiency. Expression of non-hydroxylatable Beclin1 P54A abrogates VHL-mediated autophagy inhibition and significantly reduces the tumor-suppressing effect of VHL. In addition, Beclin1 P54-OH levels are inversely correlated with autophagy levels in wild-type VHL-expressing human ccRCC specimens, and with poor patient prognosis. Furthermore, combined treatment of VHL-deficient mouse tumors with autophagy inhibitors and HIF2α inhibitors suppresses tumor growth. These findings reveal an unexpected mechanism by which VHL suppresses tumor growth, and suggest a potential treatment for ccRCC through combined inhibition of both autophagy and HIF2α. Synopsis: PHD1-mediated prolyl hydroxylation targets HIF-1α for VHL-dependent ubiquitination and is a key step in the cell's oxygen sensing machinery. This work shows that PHD1 and VHL also inhibit Beclin1 and autophagy initiation, with dysregulation leading to clear-cell renal cell carcinoma progression. PHD1 mediates Beclin1 Pro54 hydroxylation on pre-autophagosomal structures in clear-cell renal cell carcinoma cells. VHL binds to Pro54-hydroxylated Beclin1 and prevents the association between ATG14L and Beclin1/VPS34. VHL inhibits VPS34-dependent PI(3)P production, autophagy initiation, and kidney tumor growth. The Von Hippel-Lindau (VHL) E3 ligase binds to proline-hydroxylated Beclin1, inhibiting the initiation of autophagy and blocking kidney tumor growth. [ABSTRACT FROM AUTHOR]

The Cu−O−Cu core has been proposed as a potential site for methane oxidation in particulate methane monooxygenase. In this work, we used density functional theory (DFT) to design a mixed‐valent CuIII−O−CuII species from an experimentally known peroxo‐dicopper complex supported by N‐donor ligands containing phenolic groups. We found that the transfer of two‐protons and two‐electrons from phenolic groups to peroxo‐dicopper core takes place, which results to the formation of a bis‐μ‐hydroxo‐dicopper core. The bis‐μ‐hydroxo‐dicopper core converts to a mixed‐valent CuIII−O−CuII core with the removal of a water molecule. The orbital and spin density analyses unravel the mixed‐valent nature of CuIII−O−CuII. We further investigated the reactivity of this mixed‐valent core for aliphatic C−H hydroxylation. Our study unveiled that mixed‐valent CuIII−O−CuII core follows a hydrogen atom transfer mechanism for C−H activation. An in‐situ generated water molecule plays an important role in C−H hydroxylation by acting as a proton transfer bridge between carbon and oxygen. Furthermore, to assess the relevance of a mixed‐valent CuIII−O−CuII core, we investigated aliphatic C−H activation by a symmetrical CuII−O−CuII core. DFT results show that the mixed‐valent CuIII−O−CuII core is more reactive toward the C−H bond than the symmetrical CuII−O−CuII core. [ABSTRACT FROM AUTHOR]

In this study, an electrochemical-assisted ferric ion/persulfate (EC/Fe3+/PS) process was proposed to degrade bezafibrate (BZF), a widespread hypolipidemic drug, in water. By promoting the reduction of Fe3+ to Fe2+ at the cathode, the introduction of an electric field successfully overcomes the limitation of non-regenerable Fe2+ inherent in Fe2+/PS systems, significantly improving the degradation efficiency of BZF. The predominant reactive species identified were •OH and SO4●−, with 1O2 also playing a role. Various key operational parameters were investigated and optimized, including the current intensity, Fe3+ dosage, PS concentration, and initial pH. With a current intensity of 50 mA, an Fe3+ concentration of 50 μΜ, a PS dosage of 50 μM, and an initial pH of 3, the degradation efficiency of BZF demonstrated an exceptional achievement, reaching up to 98.8% within 30 min. The influence of anions and humic acid was also assessed. An LC/TOF/MS analysis revealed four major degradation pathways of BZF: hydroxylation, amino bond cleavage, dechlorination, and fibrate chain removal. The acute and chronic toxicities of BZF and its degradation intermediates were then assessed using the ECOSAR program. These findings highlight the wide-ranging applications of the EC/Fe3+/PS system and its potential for remediating water contaminated with micropollutants. [ABSTRACT FROM AUTHOR]

The purpose of this article is to provide a study of the hydroxylation reaction optimization of epoxidized soybean oil using a mathematical model based on surface response methodology. The variables were selected based on previous studies of the reaction. The three most influential factors are the time, the methanol ratio, and the catalyst ratio. Potentiometric characterization of the hydroxyl index allowed the influence of these factors and their interactions to be measured. It was possible to quantify these influences using multivariate regression. The results show that the three selected factors influenced the reaction yield positively; however, there were some interactions, such as an interaction between time and methanol and the interaction between time and catalyst, which had a negligible influence. The coefficients of the formulas used to construct the mathematical model were obtained from the influence values. The model was able to predict the optimum variable levels for an acceptable reaction yield efficiently and accurately. These levels were: time 244.4 min; methanol:oil ratio 1:4, and catalyst percentage 15.34%. The characterization of the hydroxylated oil product was carried out using Fourier‐transform infrared (FTIR) spectroscopy proton nuclear magnetic resonance (1H‐NMR) and carbon‐13 nuclear magnetic resonance (13C‐NMR) spectroscopy. [ABSTRACT FROM AUTHOR]

In this work, the synthesis and characterization of a heterogeneous photocatalyst based on spherical silica nanoparticles superficially modified with anthraquinone 2‐carboxylic acid (AQ−COOH) are presented. The nanomaterial was characterized by TEM, SEM, FT‐IR, diffuse reflectance, fluorescence, NMR, DLS, XRD and XPS. These analyses confirm the covalent linking of AQ−COOH with the NH2 functionality in the nanomaterial and, more importantly, the photocatalyst retains its photophysical properties once bound. The heterogeneous photocatalyst was successfully employed in the aerobic hydroxylation of arylboronic acids to phenols under sustainable reaction conditions. Phenols were obtained in high yields (up to 100 %) with low catalyst loading (3.5 mol %), reaching TOF values of 3.7 h−1. Using 2‐propanol as solvent at room temperature, the visible light photocatalysis produced H2O2 as a key intermediate to promote the aerobic hydroxylation of arylboronic acids. The heterogeneous photocatalyst was reused at least 5 times, without modification of the nanomaterial structure and morphology. This simple heterogeneous system showed great catalytic activity under sustainable reaction conditions. [ABSTRACT FROM AUTHOR]

Site‐selective C(sp3)−H functionalization of unreactive hydrocarbons is always challenging due to its inherited chemical inertness, slightly different reactivity of various C−H bonds, and intrinsically high bond dissociation energies. Here, a site‐selective C−H alkylation of naphthoquinone with unactivated hydrocarbons using Mn2(CO)10 as a catalyst under blue‐light (457 nm) irradiation without any external acid or base and pre‐functionalization is presented. The selective C−H functionalization of tertiary over secondary and secondary over primary C(sp3)−H bonds in abundant chemical feedstocks was achieved, and hydroxylation of quinones was realized in situ by employing the developed methodology. This protocol provides a new catalytic system for the direct construction of high‐value‐added compounds, namely, parvaquone (a commercially available drug used to treat theileriosis) and its derivatives under ambient reaction conditions. Moreover, this operationally simple protocol applies to various linear‐, branched‐, and cyclo‐alkanes with high degrees of site selectivity under blue‐light irradiated conditions and could provide rapid and straightforward access to versatile methodologies for upgrading feedstock chemicals. Mechanistic insight by radical trapping, radical scavenging, EPR, and other controlled experiments well corroborated with DFT studies suggest that the reaction proceeds by a radical pathway. [ABSTRACT FROM AUTHOR]

The development of photocatalysts that are effective in different organic processes is a topic of great interest to researchers in materials chemistry. Herein, we report the design and synthesis of a new covalent triazine framework (CTF) built by acid-catalyzed trimerization of 4,4′-(benzo[b]benzo[4,5]thieno[2,3-d]thiophene-2,7-diyl)dibenzonitrile activated by microwaves that generates a new organic polymer, DPhBTBT-CTF. This CTF exhibits visible-light absorption due to the electron-donating BTBT units and the extended π-conjugated framework with the electron-acceptor triazine node and proves to be an efficient and versatile metal-free heterogeneous photocatalyst for different organic processes such as selective oxidations of both sulfides and benzyl alcohols to sulfoxides and benzaldehydes, respectively or the oxidative bromination of electron rich aromatic compounds. Moreover, two different proof of concept reactions were tested: the Diels–Alder cycloaddition and the hydroxylation of boronic acids. Heterogeneity studies confirmed that this photocatalyst can be recycled without significant loss of selectivity, and also some mechanistic tests suggested the preferred oxidation pathway. [ABSTRACT FROM AUTHOR]