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BACKGROUND: Organophosphate esters (OPEs) are flame retardants and plasticizers used in consumer products. OPEs are found ubiquitously throughout the environment with high concentrations in indoor house dust. Exposure to individual OPEs is associated with immune dysfunction, particularly in macrophages. However, OPEs exist as complex mixtures and the effects of environmentally relevant mixtures on the immune system have not been investigated. OBJECTIVES: The objectives of this study were to evaluate the toxicity of an environmentally relevant mixture of OPEs that models Canadian house dust on macrophages using phenotypic and functional assessments in vitro. METHODS: High-content live-cell fluorescent imaging for phenotypic biomarkers of toxicity in THP-1 macrophages treated with the OPE mixture was undertaken. We used confocal microscopy and cholesterol analysis to validate and expand on the observed OPE-induced lipid phenotype. Then, we used flow cytometry and live-cell imaging to conduct functional tests and uncover mechanisms of OPE-induced phagocytic suppression. Finally, we validated our THP-1 findings in human primary peripheral blood mononuclear cells (hPBMC) derived macrophages. RESULTS: Exposure to non-cytotoxic dilutions of the OPE mixture resulted in higher oxidative stress and disrupted lysosome and lipid homeostasis in THP-1 and primary macrophages. We further observed that phagocytosis of apoptotic cells in THP-1 and primary macrophages was lower in OPEexposed cells vs. controls. In THP-1 macrophages, phagocytosis of both Gram-positive and Gram-negative bacteria was also lower in OPE-exposed cells vs. controls. Additionally, the OPE mixture altered the expression of phagocytic receptors linked to the recognition of phosphatidylserine and pathogen-associated molecular patterns. DISCUSSION: The results of this in vitro study suggested that exposure to an environmentally relevant mixture of OPEs resulted in higher lipid retention in macrophages and poor efferocytic response. These effects could translate to enhanced foam cell generation resulting in higher cardiovascular mortality. Furthermore, bacterial phagocytosis was lower in OPE-exposed macrophages in an in vitro setting, which may indicate the potential for reduced bacterial clearance in models of infections. Taken together, our data provide strong evidence that mixtures of OPEs can influence the biology of macrophages and offer new mechanistic insights into the impact of OPE mixtures on the immune system. https://doi.org/10.1289/EHP13869, Introduction Manufacturers use organophosphate esters (OPEs), the most prominent class of flame retardants,in consumer and commercial products to prevent or reduce the spread of fire. (1,2) The use of OPEs [...]

Determining the structure and phenotypic context of molecules detected in untargeted metabolomics experiments remains challenging. Here we present reverse metabolomics as a discovery strategy, whereby tandem mass spectrometry spectra acquired from newly synthesized compounds are searched for in public metabolomics datasets to uncover phenotypic associations. To demonstrate the concept, we broadly synthesized and explored multiple classes of metabolites in humans, including N-acyl amides, fatty acid esters of hydroxy fatty acids, bile acid esters and conjugated bile acids. Using repository-scale analysis1,2, we discovered that some conjugated bile acids are associated with inflammatory bowel disease (IBD). Validation using four distinct human IBD cohorts showed that cholic acids conjugated to Glu, Ile/Leu, Phe, Thr, Trp or Tyr are increased in Crohn's disease. Several of these compounds and related structures affected pathways associated with IBD, such as interferon-γ production in CD4+ T cells3 and agonism of the pregnane X receptor4. Culture of bacteria belonging to the Bifidobacterium, Clostridium and Enterococcus genera produced these bile amidates. Because searching repositories with tandem mass spectrometry spectra has only recently become possible, this reverse metabolomics approach can now be used as a general strategy to discover other molecules from human and animal ecosystems.

BackgroundWidespread exposure to organophosphate ester (OPE) flame retardants with potential reproductive toxicity raises concern regarding the impacts of gestational exposure on birth outcomes. Previous studies of prenatal OPE exposure and birth outcomes had limited sample sizes, with inconclusive results.ObjectivesWe conducted a collaborative analysis of associations between gestational OPE exposures and adverse birth outcomes and tested whether associations were modified by sex.MethodsWe included 6,646 pregnant participants from 16 cohorts in the Environmental influences on Child Health Outcomes (ECHO) Program. Nine OPE biomarkers were quantified in maternal urine samples collected primarily during the second and third trimester and modeled as log2-transformed continuous, categorized (high/low/nondetect), or dichotomous (detect/nondetect) variables depending on detection frequency. We used covariate-adjusted linear, logistic, and multinomial regression with generalized estimating equations, accounting for cohort-level clustering, to estimate associations of OPE biomarkers with gestational length and birth weight outcomes. Secondarily, we assessed effect modification by sex.ResultsThree OPE biomarkers [diphenyl phosphate (DPHP), a composite of dibutyl phosphate and di-isobutyl phosphate (DBUP/DIBP), and bis(1,3-dichloro-2-propyl) phosphate] were detected in >85% of participants. In adjusted models, DBUP/DIBP [odds ratio (OR) per doubling=1.07; 95% confidence interval (CI): 1.02, 1.12] and bis(butoxyethyl) phosphate (OR for high vs. nondetect=1.25; 95% CI: 1.06, 1.46), but not other OPE biomarkers, were associated with higher odds of preterm birth. We observed effect modification by sex for associations of DPHP and high bis(2-chloroethyl) phosphate with completed gestational weeks and odds of preterm birth, with adverse associations among females. In addition, newborns of mothers with detectable bis(1-chloro-2-propyl) phosphate, bis(2-methylphenyl) phosphate, and dipropyl phosphate had higher birth weight-for-gestational-age z-scores (β for detect vs. nondetect=0.04-0.07); other chemicals showed null associations.DiscussionIn the largest study to date, we find gestational exposures to several OPEs are associated with earlier timing of birth, especially among female neonates, or with greater fetal growth. https://doi.org/10.1289/EHP13182.

A metal-free and sustainable visible-light-mediated method for the preparation of organic nitrate esters has been developed through the aerobic nitrooxylation reaction of α-diazoesters and cyclic ethers with t-BuONO in the presence of dioxygen. This protocol provides an efficient approach to access nitrate esters with the advantages of clean energy, broad substrate scope, green oxidants, operational simplicity, and mild conditions. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate a method for the syntheses of sulfinamides and sulfinate esters using a novel sulfur(IV) fluoride exchange reaction with organometallic reagents. Our strategy involves the addition of an amine or alcohol nucleophile to thionyl fluoride, acting as a S(IV) SuFEx hub, followed by an organometallic reagent. This approach allows efficient access to sulfinamides (45–91% yields) and sulfinate esters (44–82% yields) in only 30 minutes. The sulfinamide and sulfinate esters also can be readily derivatized to the corresponding S(VI) sulfonamides, sulfonate esters, sulfonimidamides, and sulfonimidates without isolation of the intermediates. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Herein, we report rhodium catalyzed N‐arylation via addition of arylboronic acids to electron‐deficient α‐iminoesters which can be prepared in high efficiency by using easily accessible β‐carbonyl esters. The reaction is highly regiospecific to achieve the N‐aryl addition efficiently with up to 99% yield under mild conditions. The corresponding product can be further efficiently converted into indoles and a series of other important building blocks. [ABSTRACT FROM AUTHOR]

Bioaromas can be produced by lipases either through their hydrolytic or (trans)esterifying activities. Therefore, this work reports the development of a lipase-catalyzed biotransformed licuri oil, forming volatile ethyl esters with odor notes resembling tropical fruits. Ethyl octanoate formation was promoted when 7.0 % (m/v) Lipozyme 435® was used to convert a grain alcohol:licuri oil mixture (51:49, v/v) at 58ºC and 70 rpm for 6 hours. The biotransformed oil has shown antimicrobial activity against Staphylococcus hominis , S. epidermidis, and Corynebacterium xerosis , bacteria associated with bad skin odor. Finally, this biotransformed oil was used without further treatments (e.g., recovery or purification procedures) to prepare two cosmetic formulations (in a dosage of 1.5 %), aiming for both fragrant and deodorant activity. • Odor-active ethyl esters were formed in lipase-biotransformed licuri oil. • 8.22 g/L ethyl octanoate was formed with 7 % lipase, 51:49 alcohol:oil ratio at 58°C. • Antibacterial activity of biotransformed oil could prevent bad skin odor. • Cosmetic formulations were prepared with 1.5 % biotransformed licuri oil. • No purification procedures were needed to use a natural fragrant mixture. [ABSTRACT FROM AUTHOR]

A general and highly enantioselective method for the preparation of tetra‐substituted 3‐hydroxyphthalide esters via isothiourea‐catalysed acylative dynamic kinetic resolution (DKR) is reported. Using (2S,3R)‐HyperBTM (5 mol %) as the catalyst, the scope and limitations of this methodology have been extensively probed, with high enantioselectivity and good to excellent yields observed (>40 examples, up to 99 %, 99 : 1 er). Substitution of the aromatic core within the 3‐hydroxyphthalide skeleton, as well as aliphatic and aromatic substitution at C(3), is readily tolerated. A diverse range of anhydrides, including those from bioactive and pharmaceutically relevant acids, can also be used. The high enantioselectivity observed in this DKR process has been probed computationally, with a key substrate heteroatom donor O⋅⋅⋅acyl‐isothiouronium interaction identified through DFT analysis as necessary for enantiodiscrimination. [ABSTRACT FROM AUTHOR]

The development of methods to allow the selective acylative dynamic kinetic resolution (DKR) of tetra‐substituted lactols is a recognised synthetic challenge. In this manuscript, a highly enantioselective isothiourea‐catalysed acylative DKR of tetra‐substituted morpholinone and benzoxazinone‐derived lactols is reported. The scope and limitations of this methodology have been developed, with high enantioselectivity and good to excellent yields (up to 89 %, 99 : 1 er) observed across a broad range of substrate derivatives incorporating substitution at N(4) and C(2), di‐ and spirocyclic substitution at C(5) and C(6), as well as benzannulation (>35 examples in total). The DKR process is amenable to scale‐up on a 1 g laboratory scale. The factors leading to high selectivity in this DKR process have been probed through computation, with an N−C=O⋅⋅⋅isothiouronium interaction identified as key to producing ester products in highly enantioenriched form. [ABSTRACT FROM AUTHOR]

We disclose herein a metal-free cascade reductive Friedel–Crafts alkylation/cyclization of keto acids/esters for the synthesis of tetralones and indanones. Owing to the simple reaction conditions and setup, this protocol features broad substrate generality, facile scalability, and remarkable functional group tolerance, including the synthesis of bioactive molecule sertraline. [ABSTRACT FROM AUTHOR]

Elemental sulfur has shown to be a promising alternative feedstock for development of novel polymeric materials with high sulfur content. However, the utilization of inverse vulcanized polymers is restricted by the limitation of functional comonomers suitable for an inverse vulcanization. Control over properties and structure of inverse vulcanized polymers still poses a challenge to current research due to the dynamic nature of sulfur‐sulfur bonds and high temperature of inverse vulcanization reactions. In here, we report for the first time the inverse vulcanization of norbornenyl pentafluorophenyl ester (NB‐PFPE), allowing for post‐modification of inverse vulcanized polymers via amidation of reactive PFP esters to yield high sulfur content polymers under mild conditions. Amidation of the precursor material with three functional primary amines (α‐amino‐ω‐methoxy polyethylene glycol, aminopropyl trimethoxy silane, allylamine) was investigated. The resulting materials were applicable as sulfur containing poly(ethylene glycol) nanoparticles in aqueous environment. Cross‐linked mercury adsorbents, sulfur surface coatings, and high‐sulfur content networks with predictable thermal properties were achievable using aminopropyl trimethoxy silane and allylamine for post‐polymerization modification, respectively. With the broad range of different amines available and applicable for post‐polymerization modification, the versatility of poly(sulfur‐random‐NB‐PFPE) as a platform precursor polymer for novel specialized sulfur containing materials was showcased. [ABSTRACT FROM AUTHOR]

A mild and efficient reaction for synthesizing esters from thioamide precursors has been established. This method is accomplished in one pot under mild conditions. The process involves the alkylation and activation of inert thioamides, which leads to the cleavage of stable C–N and C–S bonds, eventually resulting in valuable esters with a broad range of substrates. The transformation can be easily carried out at room temperature using thioamide substrates, reactants, and activating agents. This protocol has been demonstrated by synthesizing important esters with applications. [ABSTRACT FROM AUTHOR]

Considerable synthetic effort has been devoted to acid‐ or base‐catalysed transesterification of alkyl salicylate with alcohol in order to synthesize salicylate esters efficiently. In this study, the transesterification of methyl salicylate with 12 different alcohols was carried out by the use of Zn dust as a catalyst. Depending on the alcohol used in the transesterification reaction, the completion of the reaction was within a range of 8–15 h at a temperature between 100 and 170°C. The use of Zn dust provided reusability and almost complete recovery with moderate to excellent yields (42%–97%). The structural elucidation of the products was performed using IR, 1H NMR, 13C NMR and GC–MS data obtained from the Wiley GC/MS Library and the in‐house "Parkim Fragrance House GC/MS Library." [ABSTRACT FROM AUTHOR]

Herein, we synthesized and used a novel pillar[5]arene with two functionalizable rims (AP5A-C10-OAc) as stationary phase in gas chromatography (GC). The AP5A-C10-OAc column (0.25 mm, i.d.) showed a high column efficiency of 4107 plates/m and medium polarity. The AP5A-C10-OAc stationary phase possesses unique amphiphilic structure, including a π-electron rich cavity and two functionalized arms composed of five nonpolar alkyl chains and five polar ester chains, and showed good separation performance for diverse types of analytes and isomers (apolar/polar, aliphatic/aromatic). Particularly, the AP5A-C10-OAc phase showed high selectivity for the challenging isomers of chloronitrobenzenes, bromonitrobenzenes, benzenediols, and iodoanilines with distinct advantages if compared with the commercial polysiloxane column. [ABSTRACT FROM AUTHOR]

Sucrose esters have been deployed as surfactants in many food products since the 1950s. In addition to their useful physical characteristics, sucrose esters also have interesting biological properties that enhance their utility. This review critically examines the broad suite of biological activities that has been attributed to both synthetically-derived and naturally-occurring sucrose esters. These include insecticidal, molluscicidal, plant growth-regulating, anti-microbial, anti-tumor, anti-oxidant, anti-depressive, neuro-protective, anti-inflammatory and anti-plasmodial effects. In addition to providing a summary of the structure-activity profiles of sucrose esters, the various known mechanisms-of action of these compounds are also discussed. Furthermore, since sucrose esters are well-known surfactants, the potential to advantageously apply their industrially desirable physical characteristics in combination with their biological properties is considered. Recent advances in synthetic chemistry that have facilitated the deployment of biologically active sucrose esters as food additives are also described. [ABSTRACT FROM AUTHOR]

Our newly developed menthyl esters of valine and isoleucine exhibit anti‐inflammatory properties beyond those of the well‐known menthol in macrophages stimulated by lipopolysaccharide (LPS) and in a mouse model of colitis induced by sodium dextran sulfate. Unlike menthol, which acts primarily through the cold‐sensitive TRPM8 channel, these menthyl esters displayed unique mechanisms that operate independently of this receptor. They readily penetrated target cells and efficiently suppressed LPS‐stimulated tumour necrosis factor‐alpha (Tnf) expression mediated by liver X receptor (LXR), a key nuclear receptor that regulates intracellular cholesterol and lipid balance. The menthyl esters showed affinity for LXR and enhanced the transcriptional activity through their non‐competitive and potentially synergistic agonistic effect. This effect can be attributed to the crucial involvement of SCD1, an enzyme regulated by LXR, which is central to lipid metabolism and plays a key role in the anti‐inflammatory response. In addition, we discovered that the menthyl esters showed remarkable efficacy in suppressing adipogenesis in 3T3‐L1 adipocytes at the mitotic clonal expansion stage in an LXR‐independent manner as well as in mice subjected to diet‐induced obesity. These multiple capabilities of our compounds establish them as formidable allies in the fight against inflammation and obesity, paving the way for a range of potential therapeutic applications. [ABSTRACT FROM AUTHOR]

The deep-processing utility of pure hydrogen sulfide (H2S) is a significant direction in natural gas chemical industry. Herein, a brand-new strategy of H2S conversion by a,b-unsaturated carboxylate esters into thiols or thioethers using task-specific carboxylate ionic liquids (ILs) as catalyst has been developed, firstly accomplishing the phase separation of product and catalyst without introducing the third component. It can be considered as a cascade reaction in which the product selectivity can be controlled by adjusting the molar ratio of H2S to a,b-unsaturated carboxylate esters. Also, the effects of ILs with different anions and cations, intermittent feeding operations, as well as pressure time kinetic behaviors on cascade reaction were investigated. Furthermore, the proposed interaction mechanism of H2S conversion using butyl acrylate catalyzed by [Emim][Ac] was revealed by DFT-based theoretical calculation. The approach enables the selfhase separation promotion of catalyst and product and achieves 99% quantitative conversion under mild conditions in the absence of solvent, making the entire process ecologically benign. High-efficiency reaction activity can still be maintained after ten cycles of the catalyst. Therefore, the good results, combined with its simplicity of operation and the high recyclability of the catalyst, make this green method environmentally friendly and costeffective. It is anticipated that this self-separation method mediated by task-specific ILs will provide a feasible strategy for H2S utilization, which will guide its application on an industrial scale. [ABSTRACT FROM AUTHOR]

We report a photochemical method for the semipinacol rearrangement of unactivated allylic alcohols. Aliphatic as well as aromatic groups participate as migrating groups, yielding a variety of α,α‐disubstituted ketones. The reaction proceeds under mild conditions and is compatible with ethers, esters, halides, nitriles, carbamates, and substituted arenes. The operationally simple and fully catalytic conditions prescribe 1 mol % benzothiazinoquinoxaline as organophotocatalyst, 0.5 mol % Co‐salen, and 10 mol % lutidinium triflate and, importantly, display reactivity complementary to procedures employing Brønsted acid. We showcase the utility of the protocol in late‐stage drug diversifications. [ABSTRACT FROM AUTHOR]

In this work, six benzothioxanthene‐based oxime esters were employed as photoinitiators for photopolymerization under visible light (LED) and sunlight. Their abilities to behave as Type I photoinitiators by mean of a photocleavage mechanism of oxime esters but also in multicomponent photoinitiating systems with an iodonium salt (through an electron transfer mechanism) were both explored with the different structures. Due to their broad absorption spectra tailing up 600 nm, photoinitiating properties of the benzothioxanthene‐based oxime esters were systematically tested under excitation with low‐intensity LED light at wavelengths of 405 nm and 450 nm. Additionally, parallel to the polymerization tests done under artificial light, the different benzothioxanthene‐based oxime esters were also investigated as solar photoinitiators and displayed a high reactivity in France (Western Europe) even in winter conditions. For the best candidates i.e. the most reactive structures, direct laser write experiments were carried out, evidencing the interest of these structures. [ABSTRACT FROM AUTHOR]

Diels‐Alder between nitroalkenes derived from a sugar scaffold and cyclopentadiene were examined. Depending on chemical structure of nitroalkene and polarity of solvent used, the reaction proceeded via the formation of a nitronate intermediate. Cyclic nitronates highly functionalized were obtained as chemically stable and stereochemically pure compounds. [3,3] sigmatropic shift of these ones afforded the Diels Alder cycloadducts in quantitative yield. Mechanistic aspects of reaction between nitroalkenes and cyclopentadiene has been studied using DFT computational methods. Nitronate derivatives are attractive intermediates and open the way for the construction of valuable compounds with potential applications. [ABSTRACT FROM AUTHOR]

We report herein a blue‐light‐promoted iron‐catalyzed reduction of carboxamides and carboxylic esters. Conducting the reaction under hydrosilylation conditions and blue light (2×24 W, 450–460 nm) in the presence of an iron(0) based pre‐catalyst, Fe(CO)4(IMes), amines and alcohols were obtained, respectively, notably at ambient conditions, whereas using white light, higher reaction temperatures up to 100 °C were required. Preliminary mechanism studies highlighted the crucial role of blue light not only to generate the catalytic active species, but also in some steps of the catalytic cycle. [ABSTRACT FROM AUTHOR]

A silver‐catalyzed regioselective one‐pot cyclization reaction of diazo reagents with fluoronitroalkenes was developed. This transformation presents a method for accessing a series of 4‐aryl‐3‐fluoropyrazoles that are substituted with various groups such as trifluoromethyl, carboxylic ester, nitrile, and phosphonate ester. Further synthetic transformations offered the corresponding fluorinated and trifluoromethylated analogues of two fungicide compounds. [ABSTRACT FROM AUTHOR]

In this manuscript a general photocatalytic approach for the synthesis of alkyl‐substituted gem‐difluoroalkenes using readily available oxime esters and 1‐bromo‐1,1‐difluoroprop‐2‐ene (BDFP) has been established. This strategy involving a radical bromo elimination provides access to a large variety of value‐added fluorinated molecules. The mild reaction conditions are compatible with many functional groups including complex natural products or drug molecules. Experimental and theoretical mechanistic investigations indicate that the efficiency of the process relies on the crucial role of imine radical, which is formed after photoexcitation via energy transfert (EnT) and decarboxylation of the oxime ester. Indeed, the imine radical would either behave as a bromine radical scavenger or an XAT promoter in this reaction. [ABSTRACT FROM AUTHOR]

The facile generation of the α‐acyloxy carboxamide radical is hereby reported for the first time, utilizing a photoredox catalyzed reaction of Passerini adducts synthesized using a 4‐formyl‐1,4‐dihydropyridine as the carbonyl component. This radical effectively engages in a Giese reaction with a range of olefins, ultimately leading to the synthesis of novel Passerini‐derived products not previously amenable to direct aldehyde‐based transformations. Consequently, the resulting strategy, developed both in batch and in flow, offers a promising opportunity to expand the chemical space accessible through the Passerini reaction, virtually incorporating “impossible” aldehydes. [ABSTRACT FROM AUTHOR]

Coumalic acid methyl ester (methyl coumalate), a biomass‐derived building block, was converted into (E)‐enaminoesters by an original uncatalyzed stereoselective 1,6‐addition/fragmentation cascade involving secondary amines. The transformation occurred under useful experimental conditions as a simple heating of a stoichiometric mixture of the starting compounds led to the desired products. The reaction could be extended to a range of alkyl coumalates and a variety of secondary amines. Given the original character of the transformation, the reaction mechanism was discussed. Therefore, the cascade is supposed to involve a 1,6‐conjugate addition followed by a fragmentation sequence leading ultimately to the decarboxylative elimination of (E)‐enaminoesters. Using this procedure, renewable coumalic acid proved to be a valuable alternative to fossil fuel‐based propiolates for the preparation of enaminoesters. [ABSTRACT FROM AUTHOR]

A facile esterification of α,β-unsaturated aldehydes with alcohols has been developed for the synthesis of esters by using bulky N-heterocyclic (NHC) carbene as a metal-free and eco-friendly organocatalyst. This new protocol has been proved to be effective with a wide substrate scope, giving selective esters in yields greater than 84% under mild conditions. Moreover, proposed synthetic strategy enables modification of various types of silsesquioxanes (SQ) which cannot or are technically difficult to be carried out with known protocols. For the first time, a one-pot sequential esterification/hydrosilylation has been successfully carried out. [ABSTRACT FROM AUTHOR]

Fluorination of azopyridine N-donors regulates the formation of either B ← N coordination adducts or a co-crystal with phenylboronic acid catechol ester. Specifically, the formation of B ← N adducts is promoted by azopyridines with up to four fluorines, while perfluorination affords a co-crystal via phenyl–perfluoropyridyl [π⋯πF] contacts. Electrostatic potential maps showed supramolecular bonding competition outcomes to be primarily determined by modulation of electron-donating capacity and π surfaces of azopyridine N-donors using fluorination. [ABSTRACT FROM AUTHOR]

A novel and highly efficient technique has been demonstrated for the transamidation of N-tert-butoxycarbonyl (N-Boc) activated secondary amides, as well as the direct amidation of esters with amines, resulting in the formation of amide bonds. This technique exhibits exceptional selectivity in cleaving N–C/O–C bonds and utilizes Co@NC as a highly efficient magnetic nano-catalyst. The method stands out for its solvent-free conditions, environmentally friendly catalyst, straightforward work-up, and the ability to easily reclaim (aided by an external magnet) and reuse the catalyst for up to five cycles without significant loss of catalytic activity, showcasing both novelty and efficiency. [ABSTRACT FROM AUTHOR]

A seven-step ex-chiral-pool synthesis of optically active 4-alkylidenetetrahydroisoquinolines was developed. Starting from 6-bromopiperonal and (S)-serine esters, N -benzylation via reductive amination gave enantiopure N -piperonyl serine esters. Subsequent NH and OH protection delivered defined (S)-serine building blocks. The best results to achieve the conversion into the corresponding serinal were obtained via a two-step sequence of NaBH4 /LiCl reduction and subsequent TEMPO oxidation. Then, chain elongation using the Masamune–Roush variant of the Horner olefination afforded ethyl (E)-4-(N -6-bromopiperonyl)-substituted pentenoates in high yields. Intramolecular Heck cyclization employing the Herrmann–Beller catalyst enabled generation of enantiopure 4-(2-ethoxycarbonylmethylidene)tetrahydroisoquinoline building blocks in high Z -selectivity. Subsequent selected functional group transformations gave carbinols and lactones, which can be used as key intermediates in crinane alkaloid total syntheses. [ABSTRACT FROM AUTHOR]

Unstable tetra(methoxycarbonyl)cyclopentadienone was investigated in the synthesis of electron-deficient cycloheptatrienes via [4+2]-cycloaddition/cycloelimination reaction with cyclopropenes. The use of its stable dimer did not afford the product although similar reactions with alkynes have been reported. Quantum chemical calculation revealed that cyclopentadienone is not generated from the dimer and the reaction with alkynes proceeds via a more complicated cycloelimination/cycloaddition/cycloelimination cascade. However, the formation of cycloheptatrienes was found favorable over the formation of the dimer. Therefore, the trapping of tetra(methoxycarbonyl)cyclopentadienone upon formation was successful to give cycloheptatrienes with five ester groups. The use of methyl coumalate as a four-electron component was successful with cyclopropenes containing only one ester group to afford only two ester groups in the product. [ABSTRACT FROM AUTHOR]

An efficient strategy for the oxidative cleavage of C ＝ C bonds in olefins to form esters with one or multiple carbon atoms less over heterogeneous cobalt/nitrogen-doped carbon catalyst with dioxygen as the oxidant was described. The protocol features a wide substrate range including the challenging inactive aliphatic and long-chain alkyl aryl olefins. The reactivity of the catalyst did not decrease after reused for seven times. Characterization and control experiments reveal that synergistic effects between the metallic Co nanoparticles and Co – Nx sites provide access to the excellent catalytic activity. [ABSTRACT FROM AUTHOR]

This study investigated the impact of the depulping of cocoa beans after pod opening, as well as the influences of pod storage (PS) and fermentation time on the fermentation dynamics and the overall quality of beans and liquors made thereof. Twelve variations were conducted in three experimental runs (with/without depulping; 1-/3-day PS; and fermentation times of 3, 4, 5, 6 or 7 days). Fermentation dynamics (e.g., temperature and pH) and the quality of dried beans (e.g., cut-test and fermentation index) and liquors (sensory assessment, quantification of cocoa key-odorants and tastants) were investigated. It was demonstrated that 17–20% of cocoa pulp, relative to the total bean-pulp-mass weight, could be mechanically removed without negatively affecting the bean quality. No significant differences were found in the percentages of well-fermented beans after 5–6 days fermentation with 1-day PS, resulting in 49 ± 9% with, and 48 ± 12% without depulping. There were no significant differences in key tastants present in the liquors; however, significantly less volatile acids and esters were found when liquors were produced from 5–6 day-fermented depulped beans, with 1-day PS, without negatively affecting the sensory profiles. This strategy allows producers to maximize the cacao fruit's value by integrating part of the pulp into the cocoa value chain. [ABSTRACT FROM AUTHOR]

The present study aimed to identify the content of astaxanthin and its esterified forms using high-performance liquid chromatography coupled with diode array and atmospheric pressure chemical ionisation mass spectrometry detection in three samples of shrimp waste. The analyses revealed twenty-one astaxanthin derivatives, including astaxanthin in free form, across all three extracts with the highest number of derivatives observed in the head extract. The shell extract had a lower content of astaxanthin and its esterified forms, with monoesterified astaxanthins being the major components, with contents ranging from 0.5–1 mg g−1. On the other hand, in both global waste and head extracts, astaxanthin diesters were found to be the dominant bioactive compounds, with contents ranging from 0.7–5.2 mg g−1 and 10.2–18.2 mg g−1, respectively. Notably, the astaxanthin content extracted from head was significantly higher compared to other extracts, indicating its potential as a valuable source of bioactive compounds. [ABSTRACT FROM AUTHOR]

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Aptamers are oligonucleotides with antibody-like binding function, selected from large combinatorial libraries. In this study, we modified a DNA aptamer library with N-hydroxysuccinimide esters, enabling covalent conjugation with cognate proteins. We selected for the ability to bind to mouse monoclonal antibodies, resulting in the isolation of two distinct covalent binding motifs. The covalent aptamers are specific for the Fc region of mouse monoclonal IgG1 and are cross-reactive with mouse IgG2a and other IgGs. Investigation into the covalent conjugation of the aptamers revealed a dependence on micromolar concentrations of Cu2+ ions which can be explained by residual catalyst remaining after modification of the aptamer library. The aptamers were successfully used as adapters in the formation of antibody-oligonucleotide conjugates (AOCs) for use in detection of HIV protein p24 and super-resolution imaging of actin. This work introduces a new method for the site-specific modification of native monoclonal antibodies and may be useful in applications requiring AOCs or other antibody conjugates. Site-specific conjugation of oligonucleotides and native proteins remains challenging. Here, the authors select covalent DNA aptamers from a library modified with N-hydroxysuccinimide esters, and show their application in the formation of antibody–oligonucleotide conjugates for protein detection. [ABSTRACT FROM AUTHOR]

A one‐pot tandem process was developed aiming at the concise and expeditious enantioselective synthesis of dihydrobenzofuran, dihydrobenzosulfone, and dihydroindole scaffolds under mild, and open‐flask conditions. This process combines the in situ generation of aryldiazonium salt directly from the anilines in methanol telescoped to an intramolecular Heck‐Matsuda reaction linked to a redox relay process to provide the final products as the dimethyl acetals. These Heck products were smoothly converted into the corresponding primary alcohols or esters. The robustness and the efficiency of the protocol are demonstrated by the synthesis of 24 enantioenriched dihydrobenzofurans, dihydrobenzosulfones, and dihydroindoles in overall yields up to 78 % in enantiomeric ratios up to 99 : 1 by a sequential 5‐step protocol. [ABSTRACT FROM AUTHOR]

A photoinduced EnT-mediated generation of sulfonamidyl radicals has been accomplished using rationally designed iminophenylacetic acid oxime ester reagents under metal-free conditions. This approach offers a mild, regio- and diastereoselective synthesis of N-sulfonyl diamines via diamination of alkenes and (hetero)arenes. [ABSTRACT FROM AUTHOR]

A photocatalytic decarboxylative functionalization of cyclopropenes is reported. Starting from a broad range of redox‐active ester‐substituted cyclopropenes, cyclopropenylphthalimides can be synthesized in the absence of a nucleophile. Alternatively, different carbon and heteroatom nucleophiles can be introduced. The transformation proceeds most probably through the formation of an aromatic cyclopropenium cation, followed by trapping with the nucleophiles. [ABSTRACT FROM AUTHOR]

Determining the content of the nutrient choline in foods and obtaining the required amount from the diet are crucial. One way to measure choline in foods is by converting choline esters to free choline via acid hydrolysis, followed by quantifying the total choline, as adopted by the AOAC method (AOAC-Choline); however, certain choline esters are difficult to hydrolyse. Here, we investigated various acid hydrolysis conditions to establish a reliable method for determining the total choline in foods by detecting free choline using highly sensitive and selective mass spectrometry. Hydrolysis in 0.055 mol/L HCl for 8 h in an autoclave (121 °C) was found to be optimal for the hydrolysis of choline esters in various foods. Twenty-four foods, including grains, seed, vegetables, fruits, mushroom, algae, fish, meats, beverage, processed foods, and egg, were measured. The trends in the total choline content were consistent with previous reports; however, the choline content was 10–20% higher than that measured using AOAC-Choline. Therefore, re-evaluation of the total choline content in foods using our constructed method is recommended. This reassessment will allow for a more reliable determination of choline intake for maintaining health. [ABSTRACT FROM AUTHOR]

A stereoselective synthesis of the C1–C13 segment of poecillastrin C has been achieved. The C1–C4 moiety was derived from diallyl l -tartrate, and the amide group at the C3 position was constructed by means of a traceless Staudinger reaction. The C1–C13 segment was submitted to model studies, including esterification with a bulky alcohol at the C1 position and Stille coupling with vinyl iodide at the C13 position. The reactivity of the C1 position was affected by the neighboring C2-protective group. When the C2 hydroxy group was protected as a TBS ether, the C1 carboxylic acid did not undergo esterification with a bulky secondary alcohol, whereas the p -methoxybenzylidene N , O -acetal afforded a 2,4-dimethyl-3-pentyl ester. Stille coupling of the C1–C13 segment with 1-iodohept-1-ene gave the southern part of the poecillastrin C macrolactam attached to simplified eastern and western parts. [ABSTRACT FROM AUTHOR]

An efficient strategy for rapid assembly of the complex substituted cyclohexene core that is present in several cyclic imine marine toxins is presented. Several of these toxins, including pinnatoxin A and recently discovered portimine A, have been the focus of much attention due to their fascinating biological activities. We demonstrate that the substituted cyclohexene-diene motif, which is a challenging feature to access synthetically, can be prepared through a stepwise Ireland–Claisen rearrangement/enyne metathesis procedure beginning from chiral esters. This approach enables a divergent strategy that can be implemented in syntheses of cyclic imines or derivatives thereof. [ABSTRACT FROM AUTHOR]

Spinal cord ischemia has serious sequelae. The aim of this study is to investigate the effects of resveratrol and caffeic acid phenyl ester (CAPE), a propolis derivative, on spinal cord injury induced by ischemia-reperfusion (IR). In our research, 30 male Wistar albino rats, 200–250 gr, were used. Before the experiment, during a week of the process, the rats were fed with these two agents, and the experimental group rats were exposed to spinal cord IR injury. At the end of the experiment, spinal cord samples were taken from the sacrificed rats. Bax, p53, nNOS, and Beclin-1 immunoreactivity moreover TUNEL (+) cells were evaluated with immunohistochemically in the IR-induced damaged rats. It has been clearly determined that the TUNEL (+) apoptotic cell number and immunopositive cells of nNOS, Beclin-1, p53, Bax were raised in the IR group. However, these increments partially were restored in the resveratrol and CAPE-fed rats with IR-induced injury. In light of our data, resveratrol, and CAPE could be beneficial in spinal cord IR injury. Although both agents provide beneficial effects, it can be said that CAPE is partially more effective in spinal cord injury caused by IR. [ABSTRACT FROM AUTHOR]

Tyrosol is a principle phenolic compound present in olive oil and wine with great pharmacological potentials due to its strong antioxidant property. Its application can be highly extended by increasing its lipophilicity through esterification. In this study, tyrosol esters were synthesized by enzymatic transesterification of tyrosol with vinyl esters, with a commercial lipase from Novozymes (Novozym 435, Candida antarctica lipase B (CALB) immobilized on macroporous acrylic resin beads) as the catalyst, both in organic solvents and in ionic liquids. Methyl tert-butyl ether (MTBE) was the best solvent, offering complete conversions towards the synthesis of tyrosol esters with varying chain lengths (C2-C18) within 1 h. Taking the enzymatic transesterification between tyrosol and vinyl acetate as the model reaction, 18 organic solvents and 24 ionic liquids were screened, and their solvent properties (i.e. hydrophobicity, polarity, viscosity, water activity, and partition coefficients of substrate and product) were correlated to the enzyme activity. Upon enzyme screening, four new lipases were found to be highly efficient, relative to the best-performed Novozym 435 and Lipozyme TLIM (Thermomyces lanuginosus lipase (TLL) immobilized on silica gel), in tyrosol ester synthesis. This work provides enzymatic methods of esterifying tyrosol that are much more efficient than those reported in literature, and will shed light on re-consideration of the roles of solvents in nonaqueous enzymology. [ABSTRACT FROM AUTHOR]

The evolution of high-frequency communication has accentuated the significance of controlling dielectric properties in polymer media. Traditionally, it has been theorized that rigid molecular chains lead to lower dielectric loss. However, the validity of this proposition at high frequencies remains uncertain. To scrutinize the correlation between chain flexibility and dielectric properties, we synthesized six poly(ester imide)s (PEIs) with systematically varied molecular chain flexibilities by modifying the ester's substitution on the aromatic ring. The introduction of ester bonds bestowed all PEI films with a low dielectric dissipation factor (Df), ranging from 0.0021 to 0.0038 at 10 GHz in dry conditions. The dry Df displayed a pattern consistent with volume polarizability (P/V). Unexpectedly, PI-mmm-T, featuring the most flexible molecular chain, exhibited the lowest dielectric loss under both dry (0.0021 @ 10 GHz) and hygroscopic (0.0029 @ 10 GHz) conditions. Furthermore, the observed increase in Df after humidity absorption suggests that the high dielectric loss of PEI in applications may be attributed to its hygroscopic nature. Molecular simulations and characterization of the aggregation structure revealed that the smaller cavities within flexible molecular chains, after close stacking, impede the entry of water molecules. Despite sacrificing high-temperature resistance, the precursor exhibited enhanced solubility properties and could be processed into high-quality films. Our research unveils new insights into the relationship between flexibility and high-frequency dielectric loss, offering innovative perspectives on synthesizing aromatic polymers with exceptional dielectric properties. [ABSTRACT FROM AUTHOR]

There is a significant trend towards the integration of natural substances with bio-polymers for fully bio-based functional composites. Polylactic acid is regarded as a promising biodegradable polymer for replacing synthetic polymers. Differing from the case of natural fiber, the incompatibility of polylactic acid with bio-based molecules prevents it from being used to fabricate high-quality sustainable composites. This work presents a simultaneous ultraviolet shielding and antibacterial finishing process of polylactic acid combined with bioactive baicalin and an eco-friendly ester, which is highlighted for (a) the lack of synthetic chemicals involved in such process, (b) adsorption enhancement achieved at a mild temperature, and (c) marginal color change on treated polylactic acid. A response surface methodology was adopted to analyze the impacts of various factors on the baicalin quantity in polylactic acid, and to optimize the treatment condition. The uptake ratio of baicalin in polylactic acid was drastically promoted from 8.5 mg/g to 21.1 mg/g using methyl cinnamate. The response surface methodology based on a central composite design experiment indicated that the usage of baicalin was the most significant factor followed by methyl cinnamate and temperature. After optimization, a very faint color depth of 1.2 was apparent, but UPF 50+ and 92% bacterial reduction could be achieved. In all, the success in strengthening of the functionalities of polylactic acid extends the applications of polylactic acid products. [ABSTRACT FROM AUTHOR]

To understand the role of an additional coordination site in the linker in chirality sensing, we designed and synthesized an S-2-methylbutanamido-substituted m-phthalic diamide-linked zinc bisporphyrinate, [Zn2(S-MAABis)] and investigated its ability to sense the chirality of amino acid esters. The 1H NMR spectra and the crystal structure showed that the amido oxygen adjacent to the chiral carbon was coordinated with zinc. NMR and UV–vis titration showed that the binding of [Zn2(S-MAABis)] to amino acid esters occurred via two equilibria, forming 1:1 and 1:2 host–guest complexes. The CD spectra suggested that [Zn2(S-MAABis)] can effectively recognize the absolute configuration of amino acid esters. The sign of the CD spectra remained unchanged during the titration, indicating that the corresponding 1:1 and 1:2 host–guest complexes had the same chirality. This is different from previously studied amino-substituted m-phthalic diamide-linked zinc bisporphyrinate [Zn2(AmBis)], which showed chirality inversion during titration. Theoretical calculations indicated that the additional coordination sites (amido or amino) in the 1:1 host–guest complexes played different roles, leading to differences in chirality. Our studies suggest that the introduction of a coordination site can influence the chirality transfer process, but the results of chirality transfers are dependent on the specific binding modes. [ABSTRACT FROM AUTHOR]

Benzoxazine dimers are a group of compounds with a variety of properties, such as anticancer properties and good chelating behaviors. The modification of the benzoxazine dimers can be carried out on the OH groups as well as the benzene moiety. There are several works reported on the property adjustment involving the use of different substituent groups on the benzene ring. Only a few works described the properties and crystallographic studies of the OH-modified benzoxazine dimer. The repulsion forces between two bulky benzoyl groups push them to be more distant compared to the unmodified benzoxazine dimer. According to the crystallographic information, the C—H···O, C—H···π, and π···π interactions hold neighbor molecules together, which consequently stabilize the crystal structure. Thermal analyses (TGA and DSC) reveal that the synthesized benzoated benzoxazine dimer is stable up to 175 °C. Hirshfeld surface analysis confirmed the presence of the C—H···O and C—H···π interactions as seen from the high contributions of the following contacts: H···H (60.6%), H···C/C···H (25.1%), and H···O/O···H (12.3%). Moreover, the observed π···π interaction is supported by the shape-index property of the corresponding Hirshfeld surface. For the solid-state photoluminescence of the di-benzoated benzoxazine dimer recorded at the excitation wavelength range from 265 to 320 nm, the emission peak at 490 nm is observed together with another peak or shoulder in the range of 440–480 nm. For all the excitation wavelengths studied, the di-benzoated dimer emits the fluorescence in the blue color shades (CIE coordinate of x at 0.137–0.142 and y at 0.200–0.262). The photoluminescence property is found to originate by the benzoate modification of the benzoxazine dimer. [ABSTRACT FROM AUTHOR]

This study investigated the effects of high-hydrostatic-pressure (HHP) treatment of varying intensity (100–600 MPa) and duration (10–30 min) on polyphenols and volatile aromatic compounds in Marselan red wine. The types and concentrations of polyphenols and volatile aromatic compounds were compared before and after HHP treatment; the results indicated that HHP treatment at 300 MPa for 20 min significantly increased the total polyphenol content to 369.70 mg/L, a rise of 35.82%. The contents of key polyphenols, such as resveratrol and protocatechuic acid, were significantly enhanced. Furthermore, while the total content of volatile aromatic compounds did not change significantly under this condition compared to the untreated samples, the concentration of ester compounds significantly increased to 1.81 times that of the untreated group, thereby enriching the floral and fruity aromas of the wine and effectively improving its aromatic profile and sensory quality. Principal component analysis (PCA) further validated the positive impact of HHP treatment on the flavor characteristics of Marselan red wine. These findings provide technical support for the use of HHP in improving wine quality. [ABSTRACT FROM AUTHOR]

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The copper‐catalyzed coupling of thiols with alcohols was achieved under air atmosphere. The reaction proceeded smoothly in the presence of a base such as Cs2CO3 or Rb2CO3 affording sulfinic esters in good yields. Furthermore, disulfides were also available in the procedure. Both sulfide‐groups on disulfide were efficiently consumed. [ABSTRACT FROM AUTHOR]