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Hydration, as a ubiquitous and vital phenomenon in nature, has attracted great attention in the field of surface science concerning the fundamental interactions between water and organic molecules. However, the role of functional group derivatization is still elusive in terms of its potential impact on hydration. By the combination of high-resolution scanning tunneling microscopy imaging and density functional theory calculations, the hydration of 9mA molecules was realized on Au(111) in real space, forming 9mA–H2O–9mA structures. In comparison with the hydration of adenine molecules, methyl derivatization is experimentally found to remotely regulate the hydration sites from the imidazole ring to the pyrimidine ring and is further theoretically revealed to allow intramolecular electron redistribution and, therefore, steer the priority of the hydration sites. These results provide sub-molecular understandings of the relationship between derivatization and hydration, which would shed light on the regulation of hydration processes in chemically and biologically related systems. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed dual C–H functionalization of substituted aromatic ketones and ester with maleimides leading to tricyclic heterocyclic molecules with good to excellent yield is reported. In this protocol, weak chelation of the carbonyl groups has been successfully utilized for the selective activation of the ortho-methyl C(sp3)–H bond instead of the ortho-C(sp2)–H bond in the presence of an external bidentate ligand Ac-Ile-OH. The reaction proceeds through two-fold C–H activation to generate a five-membered cyclic ring. The first C–H activation takes place selectively at the benzylic position followed by a second C–H bond activation at the meta position. The protocol demonstrates compatibility among diverse substituted aromatic ketones and ester as well as various substituted maleimides. Further derivatization of the tricyclic ketone to an alcohol exhibits the synthetic applicability of the protocol. Also, a plausible reaction mechanism has been proposed. [ABSTRACT FROM AUTHOR]

The catalytic access of silicon‐stereogenic organosilanes remains a big challenge, and largely depends on the desymmetrization of the symmetric precursors with two identical substitutes attached to silicon atom. Here we report the construction of silicon‐stereogenic organosilanes via catalytic kinetic resolution of racemic monohydrosilanes with good to excellent selectivity factors. Both Si‐stereogenic dihydrobenzosiloles and Si‐stereogenic monohydrosilanes could be efficiently accessed in one single operation via Rh‐catalyzed enantioselective intramolecular hydrosilylation, employing (R,R)‐Et‐DuPhos as the optimal ligand. This catalytic protocol features mild conditions, a low catalyst loading (0.1 mol % [Rh(cod)Cl]2), high stereoinduction (S factor up to 152), and excellent scalability. Moreover, further derivatizations led to the efficient synthesis of uncommon middle‐size (7‐ and 8‐membered) Si‐stereogenic silacycles. Preliminary mechanistic study indicates this reaction might undergo a modified Chalk–Harrod mechanism. [ABSTRACT FROM AUTHOR]

The catalytic access of silicon‐stereogenic organosilanes remains a big challenge, and largely depends on the desymmetrization of the symmetric precursors with two identical substitutes attached to silicon atom. Here we report the construction of silicon‐stereogenic organosilanes via catalytic kinetic resolution of racemic monohydrosilanes with good to excellent selectivity factors. Both Si‐stereogenic dihydrobenzosiloles and Si‐stereogenic monohydrosilanes could be efficiently accessed in one single operation via Rh‐catalyzed enantioselective intramolecular hydrosilylation, employing (R,R)‐Et‐DuPhos as the optimal ligand. This catalytic protocol features mild conditions, a low catalyst loading (0.1 mol % [Rh(cod)Cl]2), high stereoinduction (S factor up to 152), and excellent scalability. Moreover, further derivatizations led to the efficient synthesis of uncommon middle‐size (7‐ and 8‐membered) Si‐stereogenic silacycles. Preliminary mechanistic study indicates this reaction might undergo a modified Chalk–Harrod mechanism. [ABSTRACT FROM AUTHOR]

AbstractThis review paper critically examines the current state of research concerning the analysis and derivatization of aldehyde, aromatic hydrocarbons and carboxylic acids components in foods and drinks samples, with a specific focus on the application of Chromatographic techniques. These diverse components, as vital contributors to the sensory attributes of food, necessitate accurate and sensitive analytical methods for their identification and quantification, which is crucial for ensuring food safety and compliance with regulatory standards. In this paper, High-Performance Liquid Chromatography (HPLC) and Gas Chromatographic (GC) methods for the separation, identification, and quantification of aldehydes in complex food matrices were reviewed. In addition, the review explores derivatization strategies employed to enhance the detectability and stability of aldehydes during chromatographic analysis. Derivatization methods, when applied judiciously, improve separation efficiency and increase detection sensitivity, thereby ensuring a more accurate and reliable quantification of aldehyde aromatic hydrocarbons and carboxylic acids species in food samples. Furthermore, methodological aspects encompassing sample preparation, chromatographic separation, and derivatization techniques are discussed. Validation was carried out in term of limit of detections are highlighted as crucial elements in achieving accurate quantification of compounds content. The discussion presented by emphasizing the significance of the combined HPLC and GC chromatography methods, along with derivatization strategies, in advancing the analytical capabilities within the realm of food science. [ABSTRACT FROM AUTHOR]

An array of cyanopyridazine derivatives have been developed through a sequence of (3+3) cycloaddition/oxidative aromatization/derivatization steps. Investigation of the physicochemical properties of these compounds shows that four have interesting fluorescence properties and have the potential to be developed into bimodal photoredox catalysts. One has been confirmed to be an photoredox catalyst in the reactions of N‐aryl‐ tetrahydroisoquinolines with phosphite, nitromethane, malonitrile and sodium thiocyanate, led to 22%–95% yields. The catalyst capabilities remain with recyclable using under the reaction conditions. [ABSTRACT FROM AUTHOR]

The investigation of collagen hydrolysates (CHs) is essential due to their widespread use in health, cosmetic, and therapeutic industries, attributing to the presence of bioactive dipeptides (DPs) and tripeptides (TPs). This study developed a novel targeted liquid chromatography–tandem mass spectrometry (LC-MS/MS) method with propyl chloroformate (PCF) derivatization to measure three bioactive peptides—Hydroxyprolyl-glycine (Hyp-Gly), Glycyl-prolyl-hydroxyproline (Gly-Pro-Hyp), and Prolyl-hydroxyproline (Pro-Hyp)—in CHs, with strong correlation coefficients (0.992, 1.000, and 0.995, respectively) and low limits of detection (LODs) of 1.40, 0.14, and 1.16 µM, respectively. Untargeted data-dependent acquisition (DDA) analyses measured peptide size distribution, while amino acid analysis assessed nutritional content. The analysis of ten commercial CHs revealed similar amino acid profiles but varied peptide lengths, indicating diverse hydrolysis conditions. Products with higher proportions of smaller peptides showed elevated levels of the targeted bioactive peptides, suggesting that a smaller peptide size may increase bioactivity. These findings can inform the optimization of CH supplements, providing consumers with detailed peptide content for more informed choices. Data are available via ProteomeXchange with the identifier PXD051699. [ABSTRACT FROM AUTHOR]

Herein, a new, direct paper-based fluorimetric method is described for the quantitative determination of glutathione (GSH) molecules in nutritional supplements. Briefly, the proposed analytical method is based on the fluorescence emission resulting from the direct and selective chemical reaction of GSH molecules with the derivatization reagent that is o-phthalaldehyde (OPA) in acidic conditions at room temperature. The intensity of the emitted fluorescence on the surface of the analytical paper devices after irradiation with a lamp at 365 nm is proportional to the concentration of GSH and is measured using a smartphone as the detector. This methodology, which is suitable for measurements in laboratories with limited resources, does not require specialized instrumentation or trained personnel. The protocol governing the proposed method is simple and easily applicable. Essentially, the chemical analyst should adjust the value of pH on the surface of the paper by adding a minimal amount of buffer solution; then, after adding a few microliters of the derivatization reagent, wait for the surface of the paper to dry and, finally, add the analyte. Subsequently, the irradiation of the sensor and the measurement of the emitted fluorescence can be recorded with a mobile phone. In the present study, several parameters affecting the chemical reaction and the emitted fluorescence were optimized, the effect of interfering compounds that may be present in dietary supplements was examined, and the stability of these paper sensors under different storage conditions was evaluated. Additionally, the chemical stability of these paper devices in various maintenance conditions was studied, with satisfactory results. The detection limit calculated as 3.3 S/N was 20.5 μmol L−1, while the precision of the method was satisfactory, ranging from 3.1% (intra-day) to 7.3% (inter-day). Finally, the method was successfully applied to three different samples of dietary supplements. [ABSTRACT FROM AUTHOR]

The possibility of cyanoacetohydrazide usage as a novel derivatizing agent is demonstrated in the presented article, and a comparison with hydroxylamine as the most commonly used reagent is provided. Optimal conditions for steroid derivatization with cyanoacetohydrazide are provided. According to the collected data, the maximum yield of derivatives was observed at pH 2.8 within 70 min at 40 °C with 5 ng/mL limit of detection for all investigated analytes. It was shown that cyanoacetohydrazide derivatives produces both syn- and anti-forms as well as hydroxylamine, and their ratios were evaluated and shown in presented work. An efficiency enchantment from two to up to five times was achieved with a novel derivatization reagent. Its applicability for qualitative analysis of steroids in urine was presented at real samples. Additionally, the reproducible fragmentation of the derivatizing agent in collision-induced dissociation offers opportunities for simplified non-targeted steroidomic screening. Furthermore, cyanoacetohydrazide increases ionization efficiency in positive mode, which can eliminate the need for redundant high-resolution instrument runs required for both positive and negative mode analyses. [ABSTRACT FROM AUTHOR]

In this study, a highly efficient magnetic molecularly imprinted polymer nanocomposite material was prepared using multi-walled carbon nanotubes as carriers. The characterization of the obtained nanocomposite material was conducted using Fourier transform infrared spectroscopy, a vibrating sample magnetometer, a thermogravimetric analyzer, a scanning electron microscope, and a transmission electron microscope. The adsorption properties of the nanocomposite material were evaluated through adsorption experiments, including static adsorption, dynamic adsorption, and selective recognition studies. The prepared nanocomposite material, serving as a selective adsorbent, was applied in magnetic solid-phase extraction. Subsequently, the derivatized samples were analyzed for glucose in fish serum using liquid chromatography–tandem mass spectrometry. Under optimal conditions, the detection limit was 0.30 ng/mL, the quantitation limit was 0.99 ng/mL, satisfactory spiked recovery rates were obtained, and the relative standard deviation was less than 1.1%. Using 2-deoxy-D-ribose as the template molecule and a structural analog of glucose allowed us to eliminate the potential template leakage in qualitative and quantitative analyses, effectively avoiding the issues of false positives and potential quantitative errors, compared to traditional methods. A method for detecting glucose levels in fish serum based on molecularly imprinted polymer technology has been successfully developed to determine the stress and health levels of fish. [ABSTRACT FROM AUTHOR]

A versatile and robust end‐group derivatization approach using oximes has been developed for the detection of oxidative degradation of synthetic polyisoprenes and polybutadiene. This method demonstrates broad applicability, effectively monitoring degradation across a wide molecular weight range through ultraviolet (UV)‐detection coupled to gel permeation chromatography. Importantly, it enables the effective monitoring of degradation via derivatization‐induced UV‐maximum shifts, even in the presence of an excess of undegraded polyene, overcoming limitations previously reported with refractive index detectors. Notably, this oxime‐based derivatization methodology is used in enzymatic degradation experiments of synthetic polyisoprenes characterized by a cis: trans ratio with the rubber oxygenase LcpK30. It reveals substantial UV absorption in derivatized enzymatic degradation products of polyisoprene with molecular weights exceeding 1000 g mol−1 ‐ an unprecedented revelation for this enzyme's activity on such synthetic polyisoprenes. This innovative approach holds promise as a valuable tool for advancing research into the degradation of synthetic polyisoprenes and polybutadiene, particularly under conditions of low organocatalytic or enzymatic degradation activity. With its broad applicability and capacity to reveal previously hidden degradation processes, it represents a noteworthy contribution to sustainable polymer chemistry. [ABSTRACT FROM AUTHOR]

This study aimed to develop a method for determining protein amino acids in microalgae using gas chromatography coupled with mass spectrometry. To efficiently hydrolyze the microalgal proteins and obtain the amino acids, a rotational central composite design was employed with two independent variables: reaction temperature (99.7–170.3 ºC) and hydrolysis time (1.1–27.9 h). The amino acids were derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide and analyzed on a gas chromatograph coupled to a mass spectrometer. Subsequently, the optimized condition was validated and used to characterize the amino acid profile of Spirulina sp. This validation adhered to the criteria set by ANVISA RDC No. 166 and European Union guidelines (SANTE 11312/2021) and consisted of assessing selectivity, limits of detection and quantification, linearity, working range, precision, and accuracy. Nineteen protein amino acids were detected and quantified from the biomass of Spirulina sp., and all validation parameters yielded satisfactory results. Our findings showed that using gas chromatography coupled with mass spectrometry proved effective and reliable for determining protein amino acids in microalgae. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A visible‐light‐enabled, photocatalyst‐free hydroacylation reaction of azodicarboxylic acid derivatives was described. This radical conjugate addition (RCA) protocol relied on the dual role of 4‐acyl‐1,4‐dihydropyridine (acyl‐DHP) reagents that besides being as radical reservoirs, they also enabled the conversion of radical adducts to anion intermediates via reduction. Under "catalyst‐oxidant‐additive free" conditions, a wide range of structurally different acyl hydrazide products were readily obtained in 56%—99% yields. The utility of this transformation was further demonstrated by the scale‐up synthesis and downstream derivatization. [ABSTRACT FROM AUTHOR]

This paper presents a novel and reliable approach for the determination of tilmicosin residues in poultry muscle and pork via gas chromatography–tandem mass spectrometry after precolumn derivatization. The samples were subjected to a quick, easy, cheap, effective, rugged, and safe preparation method, solid-phase extraction, hydrogenation, gel chromatography separation, acid hydrolysis, and derivatization with pyridine and acetic anhydride. For the blank spiked samples at the limit of quantification, 0.5 times the maximum residue limit (MRL), the MRL, and 2.0 times the MRL, the recoveries were from 76.91 to 87.99% with a precision of 2.04–5.47%. The limits of detection and quantification were 2.3–4.4 and 6.2–9.8 µg kg−1, respectively. The protocol was validated and real samples analyzed to demonstrate its practical application. [ABSTRACT FROM AUTHOR]

A synthetic protocol was developed to synthesize highly functionalized 3‐furylmethyl chromones from enynones and o‐hydroxyphenyl enaminones via silver‐catalyzed cascade bis‐heteroannulation reaction. This strategy features broad substrate scope and good functional group tolerance. Furthermore, the 3‐furylmethyl chromone skeleton shows the potential synthetic application value through further gram‐scale synthesis and derivatization. [ABSTRACT FROM AUTHOR]

A DBU‐promoted [3+2] cyclization/retro‐Mannich cascade reaction of N‐aminoisoquinolinium and N‐aminoquinolinium derivatives with para‐quinone methides has been established, employing a C=C double bond cleavage. A broad range of N‐aminoquinolinium salts, N‐aminoisoquinolinium salts, and para‐quinone methides are well tolerated, providing the corresponding rearrangement products. Moreover, scaled‐up reactions and diverse derivatizations of the products were also investigated and discussed. [ABSTRACT FROM AUTHOR]

Citrus reticulata dropped fruits are generally discarded as waste, causing environmental pollution and losses to farmers. In the present study, column chromatography has been used to isolate quinic acid (1,3,4,5-tetrahydroxycyclohexane-1-carboxylic acid) from the ethyl acetate fraction of a methanol extract of citrus fruits dropped in April. Quinic acid is a ubiquitous plant metabolite found in various plants and microorganisms. It is an important precursor in the biosynthesis of aromatic natural compounds. It was further derivatized into 3,4-o-isopropylidenequinic acid 1,5-lactone (QA1), 1,3,4,5-tetraacetoxycyclohexylaceticanhydride (QA2), and cyclohexane-1,2,3,5- tetraone (QA3). These compounds were further tested for their antibacterial potential against the foodborne pathogens Staphylococcus aureus, Bacillus spp., Yersinia enterocolitica, and Escherichia coli. QA[sub 1] exhibited maximum antibacterial potential (minimum inhibitory concentration; 80-120 µg/mL). QA1 revealed synergistic behavior with streptomycin against all the tested bacterial strains having a fractional inhibitory concentration index ranging from 0.29 to 0.37. It also caused a significant increase in cell constituent release in all the tested bacteria compared to the control, along with prominent biofilm reduction. The results obtained were further checked with computational studies that revealed the best docking score of QA1 (-6.30 kcal/ mol, -5.8 kcal/mol, and -4.70 kcal/mol) against β-lactamase, DNA gyrase, and transpeptidase, respectively. The absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis revealed that the drug-like properties of QA1 had an ideal toxicity profile, making it a suitable candidate for the development of antimicrobial drugs. [ABSTRACT FROM AUTHOR]

Acinetobacter baumannii has developed multiple drug resistances, posing a significant threat to antibiotic efficacy. LysECD7, an endolysin derived from phages, could be a promising therapeutic agent against multi-drug resistance A. baumannii. In this study, in order to further enhance the antibacterial efficiency of the engineered LysECD7, a few lipopolysaccharide-interacting peptides (Li5, MSI594 and Li5-MSI) were genetically fused with LysECD7. Based on in vitro antibacterial activity, the fusion protein Lys-Li5-MSI was selected for further modifications aimed at extending its half-life. A cysteine residue was introduced into Lys-Li5-MSI through mutation (Lys-Li5-MSIV12C), followed by conjugation with a C16 fatty acid chain via a protonation substitution reaction(V12C-C16). The pharmacokinetic profile of V12C-C16 exhibited a more favorable characteristic in comparison to Lys-Li5-MSI, thereby resulting in enhanced therapeutic efficacy against lethal A. baumannii infection in mice. The study provides valuable insights for the development of novel endolysin therapeutics and proposes an alternative therapeutic strategy for combating A. baumannii infections. [ABSTRACT FROM AUTHOR]

The design and synthesis of analogs of natural products can be a valuable source of medicinal preparations for the pharmaceutical industry. In the present study, the structural elucidation of eleven derivatives of 2,4-dihalogeno substituted synthetic analogues of the natural compound carvacrol was carried out by means of NMR experiments, and of another thirteen by DFT calculations. By selective NOE experiments and the irradiation of CH signals of the isopropyl group, individual conformers were assigned as syn and anti. By comparing GIAO/B3LYP/6-311++G(d,p)-calculated and experimentally measured vicinal 3JCH spin-spin constants, this assignment was confirmed. An unusual relationship is reported for proton-carbon vicinal couplings: 3JCH (180°) < 3JCH (0°). The conformational mobility of carvacrols was studied by 2D EXSY spectra. The application of homonuclear decoupling technique (HOBS) to these spectra simplifies the spectra, improves resolution without reducing the sensitivity, and allows a systematic examination of the rotational barrier of all compounds via their CH signals of the isopropyl group in a wider temperature interval. The rate constants of the isopropyl rotation between syn and anti conformers were determined and the corresponding energy barriers (14–17 kcal/mol) were calculated. DFT calculations of the energy barriers in carvacrol derivatives allowed the determination of the steric origin of the restricted isopropyl rotation. The barrier height depends on the size of the 2- and 4-position substituents, and is independent of the derivatization of the OH group. [ABSTRACT FROM AUTHOR]

The accurate detection of biogenic amines (BAs) is an important means of ensuring the quality and safety of cephalopod seafood products. In this study, the pre‐column derivatization of high‐performance liquid chromatography (HPLC) was optimized using dansyl chloride (Dns‐Cl) to detect BAs in octopus, cuttlefish, and squid. The reasons for the formation of BAs were investigated by assessing their decarboxylase activity and the rates of decomposition. The findings demonstrated that using Dns‐Cl to optimize pre‐column derivatization enabled the separation of nine different BAs. The detection limits ranged from 0.07 to 0.25 mg/L, and the results exhibited a high level of linearity (R2 ≥ 0.997). The decarboxylase activity and biodegradation rate positively correlated with the formation of BAs at temperatures below 0°C. Notably, the decarboxylase activity of octopus, cuttlefish, and squid exhibited a significant increase with prolonged storage time, and formyltransferase and carbamate kinase may be the key decarboxylase in cephalopod products. These findings serve as a valuable reference for further investigations into the mechanisms behind BAs production and the development of control technologies for BAs in cephalopod products. This study has successfully demonstrated the effectiveness of the Dns‐Cl pre‐column derivatization‐HPLC method in accurately and efficiently detecting BAs in octopus, cuttlefish, and squid. Moreover, it highlights the influence of decarboxylase content and biodegradation rate on the formation of BAs. Importantly, this method can serve as a reference for detecting BAs in various seafood products. [ABSTRACT FROM AUTHOR]

RNA‐based tools for biological and pharmacological research are raising an increasing interest. Among these, RNA aptamers whose biological activity can be controlled via illumination with specific wavelengths represent an important target. Here, we report on a proof‐of‐principle study supporting the viability of a systematic use of Morita‐Baylis‐Hillman adducts (MBHAs) for the synthesis of light‐responsive RNA building blocks. Accordingly, a specific acetylated MBHA derivative was employed in the functionalization of the four natural RNA bases as well as two unnatural bases (5‐aminomethyl uracil and 5‐methylaminomethyl uracil). The results reveal a highly selective functionalization for both unnatural bases. The conjugation products were then investigated spectroscopically, photochemically and computationally. It is shown that when a single light‐responsive unit is present (i. e. when using 5‐methylaminomethyl uracil), the generated unnatural uracil behaves like a cinnamic‐framework‐based photochemical switch that isomerizes upon illumination through a biomimetic light‐induced intramolecular charge transfer mechanism driving a barrierless and, therefore, ultrafast reaction path. [ABSTRACT FROM AUTHOR]

We report herein an enantioselective [3+3] annulation of indoline‐2‐thiones with yne–enones by chiral dinuclear zinc catalysts via a Brønsted base and Lewis acid cooperative activation model. This transformation proceeded through sequential conjugate addition, allenyl ketone formation and intramolecular sulfa‐Michael 6‐endo‐trig cyclization. A range of enantioenriched tetrahydrothiopyrano[2,3‐b]indole derivatives bearing an exocyclic double bond were obtained in moderate yields with excellent stereoselectivities (up to 20 : 1 dr, 20:1 Z/E ratio and 95% ee). Late‐stage functionalization, large‐scale experiment and further derivatizations were also explored. [ABSTRACT FROM AUTHOR]

The transmetalation triggered rhodium‐catalyzed C−H bond activation and tandem annulation of 2‐biphenylboronic acids with sulfoxonium ylides or iodonium ylides has been developed. Various products of phenanthrenes were constructed under redox‐neutral conditions in 34–86% yields. Several mechanism exploration experiments and derivatization reactions were conducted in sequence to gain a deeper understanding of the process and the potential of this transformation. It offers an alternative approach for the synthesis of phenanthrene derivatives. [ABSTRACT FROM AUTHOR]

Fatty acids (FAs) have attracted many interests for their pivotal roles in many biological processes. Imbalance of FAs is related to a variety of diseases, which makes the measurement of them important in biological samples. Over the past two decades, mass spectrometry (MS) has become an indispensable technique for the analysis of FAs owing to its high sensitivity and precision. Due to complex matrix effect of biological samples and inherent poor ionization efficiency of FAs in MS, sample preparation including extraction and chemical derivatization prior to analysis are often employed. Here, we describe an updated overview of FA extraction techniques, as well as representative derivatization methods utilized in different MS platforms including gas chromatography-MS, liquid chromatography-MS, and mass spectrometry imaging based on different chain lengths of FAs. Derivatization strategies for the identification of double bond location in unsaturated FAs are also summarized and highlighted. The advantages, disadvantages, and prospects of these methods are compared and discussed. This review provides the development and valuable information for sample pretreatment approaches and qualitative and quantitative analysis of interested FAs using different MS-based platforms in complex biological matrices. Finally, the challenges of FA analysis are summarized and the future perspectives are prospected. [ABSTRACT FROM AUTHOR]

A catalyst free oxone mediated synthesizing N-alkyl 1, 4-dihydroquinoxaline-2,3-dione has been developed by oxidation of the N-alkyl quinoxalin-2(1H)-one. The developed method is a novel, safest, cost-effective, industrially viable method and applicable for N-substituted and without substitution of 1,4-dihydroquinoxaline-2,3-dione. Consequently, the process is applicable to a broad spectrum of functionality. The reaction can be performed in all organic solvents without any further heating with an extended time and without generating side products. This novel synthetic methodology using Oxone is believed to be the shortest and most efficient to prepare various key intermediates which can be used for further derivatization to make the different biologically active molecules, the key feature of this methodology is not solvent specific, all organic solvents giving the optimum purity and quality using the same reaction condition. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The azepine ring is a prominent structural scaffold in biologically significant molecules. In this study, we present a Ni(II)‐catalyzed asymmetric difunctionalization of alkynes, involving intermolecular regioselective arylation and intramolecular nitrile addition, enabling the synthesis of enantioenriched azepine derivatives. This reaction simultaneously installs an all‐carbon quaternary stereocenter and introduces an unprotected imine functionality, showing great promise for subsequent transformations. The reaction exhibits good tolerance toward various functional groups, resulting in high yields and enantioselectivities. The synthetic utility of this methodology is further demonstrated through gram‐scale synthesis and product derivatization. This research offers an efficient approach to the synthesis of seven‐membered nitrogen heterocycles. [ABSTRACT FROM AUTHOR]

Optical Activity, Or Chirality, Is an Important Characteristic of Many Chemical Compounds. Various Industries Use Organic Compounds with Stereo Genic Centers, Which Can Affect Their Properties. Investigating The Attributes of Each Drug Enantiomer Is Crucial, As Only One Typically Exhibits Activity. Enantioselective Chromatography Plays a Valuable Role in Producing Pure Compounds and Developing Chiral Drugs. Advancements In Chiral Methods Within the Pharmaceutical Industry, Traditionally Reliant on Liquid Chromatography, Should Be Assessed. [ABSTRACT FROM AUTHOR]

Algal alginates, which consist of two uronic acids (i.e. D-mannuronate and L-guluronate), are important resources for a lot of industrial materials. The ratio of D-mannuronate to L-guluronate influences the physical properties of polysaccharide preparations and gels in industry. Furthermore, the influences of the percentage and configuration of each uronic acid oligomer on biological and physiochemical properties of polysaccharides have also been reported. Therefore, a highly sensitive analytical technique for uronic acids and their oligomers would be useful for both biological studies and manufacturers' quality control. To develop a fluorimetric high-performance liquid chromatography (HPLC) technique for microanalysis for uronic acid monomers and oligomers, a saline mobile phase and the postcolumn fluorimetric determination system of reducing saccharides with benzamidine were combined. Fluorescence measurement was performed at 288 nm for excitation and 470 nm for emission. A linear gradient elution system was found to be a suitable method for the simultaneous microanalysis of uronic acid monomers and oligomers. The proposed method was successfully applied to uronic acid microanalysis and should prove useful for automated simultaneous microanalysis of uronic acid monomers and oligomers in alginate hydrolysates. [ABSTRACT FROM AUTHOR]

Overcoming the limited bioavailability and extensive metabolism of effective in vitro drugs remains a challenge that limits the translation of promising drugs into clinical trials. Resveratrol, despite its well-reported therapeutic benefits, is not metabolically stable and thus has not been utilized as an effective clinical drug. This is because it needs to be consumed in large amounts to overcome the burdens of bioavailability and conversion into less effective metabolites. Herein, we summarize the more relevant approaches to modify resveratrol, aiming to increase its biological and therapeutic efficacy. We discuss combination therapies, derivatization, and the use of resveratrol nanoparticles. Interestingly, the combination of resveratrol with established chemotherapeutic drugs has shown promising therapeutic effects on colon cancer (with oxaliplatin), liver cancer (with cisplatin, 5-FU), and gastric cancer (with doxorubicin). On the other hand, derivatizing resveratrol, including hydroxylation, amination, amidation, imidation, methoxylation, prenylation, halogenation, glycosylation, and oligomerization, differentially modifies its bioavailability and could be used for preferential therapeutic outcomes. Moreover, the encapsulation of resveratrol allows its trapping within different forms of shells for targeted therapy. Depending on the nanoparticle used, it can enhance its solubility and absorption, increasing its bioavailability and efficacy. These include polymers, metals, solid lipids, and other nanoparticles that have shown promising preclinical results, adding more "hype" to the research on resveratrol. This review provides a platform to compare the different approaches to allow directed research into better treatment options with resveratrol. [ABSTRACT FROM AUTHOR]

Oxidation products of monoterpenes (C10H16) play a significant role as precursors for secondary organic aerosol formation. They contain several structural isomers with multifunctional groups. However, only a few of these isomers have been identified experimentally. We describe a measurement technique for identifying oxygen-containing functional groups (carbonyl, carboxyl, and hydroxyl groups) included in monoterpene oxidation products. This technique involves (i) three derivatization reactions (oximation of carbonyls by O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine, methyl esterification of carboxylic acids by trimethylsilyl diazomethane, and acylation of alcohols by acetic anhydride), (ii) no preseparation high-resolution electrospray ionization mass spectrometry, and (iii) collision-induced dissociation. This technique was applied to functional group analysis of ozonolysis products for α-pinene. Multifunctional groups of known ozonolysis products were accurately identified. Furthermore, we successfully estimated the multifunctional groups of products that have not been previously reported. [ABSTRACT FROM AUTHOR]

Introduction: For many samples studied by GC-based metabolomics applications, extensive sample preparation involving extraction followed by a two-step derivatization procedure of methoximation and trimethylsilylation (TMS) is typically required to expand the metabolome coverage. Performing normalization is critical to correct for variations present in samples and any biases added during the sample preparation steps and analytical runs. Addressing the totality of variations with an adequate normalization method increases the reliability of the downstream data analysis and interpretation of the results. Objectives: Normalizing to sample mass is one of the most commonly employed strategies, while the total peak area (TPA) as a normalization factor is also frequently used as a post-acquisition technique. Here, we present a new normalization approach, total derivatized peak area (TDPA), where data are normalized to the intensity of all derivatized compounds. TDPA relies on the benefits of silylation as a universal derivatization method for GC-based metabolomics studies. Methods: Two sample classes consisting of systematically incremented sample mass were simulated, with the only difference between the groups being the added amino acid concentrations. The samples were TMS derivatized and analyzed using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC-TOFMS). The performance of five normalization strategies (no normalization, normalized to sample mass, TPA, total useful peak area (TUPA), and TDPA) were evaluated on the acquired data. Results: Of the five normalization techniques compared, TUPA and TDPA were the most effective. On PCA score space, they offered a clear separation between the two classes. Conclusion: TUPA and TDPA carry different strengths: TUPA requires peak alignment across all samples, which depends upon the completion of the study, while TDPA is free from the requirement of alignment. The findings of the study would enhance the convenient and effective use of data normalization strategies and contribute to overcoming the data normalization challenges that currently exist in the metabolomics community. [ABSTRACT FROM AUTHOR]

After the use of chemical weapons, there is a gradual spontaneous decomposition of chemical warfare agents (CWAs), and only degradation products can be present at the time of sample collection. Depending on the type of parent compound, these are most often acids, alcohols, or thiols. This article deals with the development and optimization of methods for the trimethylsilylation of controlled alcohols that outperforms the currently widely used method with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) prior to gas chromatographic identification. Thiodiglycol (TDG) was chosen as a model alcohol for the development and optimization of methods. Nine trimethylsilylating agents were tested as derivatization agents. For each reagent, the method was optimized in terms of reaction medium (seven tested solvents), reaction time, and temperature. The temporal stability of the resulting derivatives and the effect of the addition of the reaction catalyst were also monitored. Subsequently, optimal methods were applied in the derivatization of N-ethyldiethanolamine, N-methyldiethanolamine, triethanolamine, 2-diisopropylaminoethanol (DIAE), and 3-quinuclidinol. The developed methods were compared in all monitored properties with the standard BSTFA-method (in acetonitrile for 30 min at 60 °C). From the developed methods, three were selected that showed similar or better sensitivity parameters than BSTFA, and at the same time were less demanding to perform. Trimethylsilylation via trimethylsilyl cyanide (TMSCN) appears to be the most successful method. In conclusion, the selected methods were applied in the analysis of contaminated environmental and urban samples – sand, acrylic paint, asphalt-aluminum paint, and concrete. The samples were measured on both a benchtop and a field gas chromatograph. [ABSTRACT FROM AUTHOR]

The abuse of herbicides has emerged as a great threat to food security. Herein, a low-background interference detection method based on UPLC-MS was developed for the simultaneous determination of glufosinate, glyphosate, and its metabolite aminomethylphosphonic acid (AMPA) in foods. Initially, this study proposed a simple and rapid pretreatment method, utilizing water extraction and PRiME HLB purification to isolate glyphosate, glufosinate, and AMPA from food samples. After the optimization of pretreatment conditions, the processed samples are then analyzed directly by ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS) without pre-column derivatization. The method can effectively reduce interference from by-products of pre-column derivatization and background substrates of food sample, showing low matrix effects (ME) ranging from − 24.83 to 32.10%. Subsequently, the method has been validated by 13 kinds of food samples. The recoveries of the three herbicides in the food samples range from 84.2 to 115.6%. The limit of detection (LOD) is lower to 0.073 mg/kg, 0.017 mg/kg, and 0.037 mg/kg, respectively. Moreover, the method shows an excellent reproducibility with relative standard deviations (RSD) within 16.9%. Thus, the method can provide high trueness, reproducibility, sensitivity, and interference-free detection to ensure human health safety. Low-background interference detection of glyphosate, glufosinate and AMPA in foods based on UPLC-MS without derivatization [ABSTRACT FROM AUTHOR]

Green solvents like ethyl acetate and acetone convert hydroxycinnamic acids into natural and unnatural derivatives such as amides, esters, and other valuable synthetic intermediates. Employing as protection‐activation a system based on an alkyl chloroformate and N‐methyl morpholine, ethyl acetate emerges as an excellent solvent for coupling O‐carbonate‐protected mixed anhydrides in acylation reactions of C‐protected amino acids, amines, and catalyzed acylation of alcohols. This results in high yields of O‐protected phenolic amides and esters. Acetone is preferred for acyl nucleophilic substitution reactions involving ionic species like free amino acids, sodium azide, and sodium hydroxide, all added in water. This approach releases the resultant O‐protected acylation products. Free phenolic compounds are promptly obtained on demand through carbonate deprotection. This synthetic method offers a simplified procedure and employs low‐cost reagents to prepare natural and unnatural hydroxycinnamic acid derivatives. [ABSTRACT FROM AUTHOR]

The limited solubility of natural cellulose in water and common organic solvents hinders its diverse applications, despite being one of the most abundant and easily accessible biopolymers on Earth. Chemical derivatization, such as cellulose carbamate (CC), offers a pathway to enhance both solubility and industrial processability. In this study, CC was synthesized by exploiting a novel type IV deep eutectic solvent (DES) composed of erbium trichloride and urea. This DES was shown to be not only an environmentally friendly reaction medium/catalyst but also actively participated in the synthetic process as a reagent. The resultant cellulose carbamate samples were characterized through FT-IR and elemental analysis. A nitrogen content value of 1.59% was afforded determining a degree of substitution corresponding to a value of 0.19. One of the key scientific advancements lies in the preparation of cellulose carbamate using a straightforward and cost-effective method. This approach utilizes non-toxic compounds, aligning with the principles of green chemistry and contributing to sustainable development in cellulose derivative production. [ABSTRACT FROM AUTHOR]

Ethoxylation is one of the common industrial process in which ethylene oxide (EO) is added to compounds containing active hydrogen atom (OH, COOH, SH, NH, etc.) to form surfactants. Alcohol ethoxylates are a major class of non‐ionic surfactants composed of an alkyl chain combined with few EO units. They are widely used in homecare products, personal care products, textiles, oilfield, construction, lubricants, food, paper, leather. The analysis of these ethoxylates possess several challenges since they contain ‘n’ number of EO units (n > 1). With increase in “n,” the product becomes more and more viscous and the boiling point increases making it difficult to analyze by normal gas chromatography (GC) technique. This paper describes a method of derivatizing these ethoxylates so that they can be eluted on a high temperature GC. BSTFA (N, O‐bis (trimethylsilyl) trifluoroacetamide) is used as the derivatizing agent (silylating agent). The ethoxylate combines with BSTFA to form the corresponding trimethylsilylated (TMS) product, which have comparatively lower boiling point. Thus, we detect trimethyl silyl product, which is the resemblance for the ethoxylated product. In this paper, we present a quantitative GC method for the ethoxylates of a few simple alcohols (2‐ethyl hexanol, glycerin), and complex vegetable oils (castor oil). The products formed during the reaction have also been identified on a gas chromatograph coupled with mass spectrometer (GCMS). GCMS shows the mass corresponding to the TMS derivatized product. The derivatization technique not only helps in increasing the volatility of these compounds but also improves the chromatographic efficiency, selectivity, and enhances the detectability. [ABSTRACT FROM AUTHOR]

An asymmetric transfer hydrogenation of 2‐oxazolones in the presence of a chiral diamine ruthenium catalyst with potassium formate as a hydrogen source and potassium carbonate as an additive in 2,2,2‐trifluoroethanol is described. A series of chiral 2‐oxazolidinones were obtained with 29%–95% yields and 86%–>99% ee's. Furthermore, gram‐scale synthesis of chiral 2‐oxazolidinone and its downstream derivatizations demonstrate the practicality of this method. [ABSTRACT FROM AUTHOR]

An unprecedented Et2Zn‐mediated gem‐dicarboxylation of C─C/C─H single bond of cyclopropanols with CO2 is disclosed, which provides a straightforward and efficient methodology for the synthesis of a variety of structurally diverse and useful malonic acids in moderate to excellent yields. The protocol features mild reaction conditions, excellent functional group compatibility, broad substrate scope, and facile derivatization of the products. DFT calculations confirm that the transition‐metal‐free transformation proceeds through a novel ring‐opening/α‐functionalization/ring‐closing/ring‐opening/β‐functionalization (ROFCOF) process, and 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) plays dual important roles in the transformation. [ABSTRACT FROM AUTHOR]

Using CBr4 as a mild oxidant, the direct C−H bond oxidation of N‐aryltetrahydroisoquinolines was achieved, giving a series of the corresponding iminium salts in high yields under metal‐ and photo‐free reaction conditions. This reaction is superior in high yields and good functional group tolerance, and the late‐stage derivatization showed that these iminium salts can readily be applied to the synthesis of the functionalized THIQs. [ABSTRACT FROM AUTHOR]

An efficient dearomative (3 + 2) cycloaddition of para-quinamines and 2-nitrobenzofurans has been developed. This reaction proceeds smoothly under mild conditions and affords a series of benzofuro[3,2-b]indol-3-one derivatives in good to excellent yields (up to 98%) with perfect diastereoselectivities (all cases > 20:1 dr). The scale-up synthesis and versatile derivatizations demonstrate the potential synthetic application of the protocol. A plausible reaction mechanism is also proposed to account for the observed reaction process. This work represents the first instance of the N-triggered dearomative (3 + 2) cycloaddition of 2-nitrobenzofurans. [ABSTRACT FROM AUTHOR]

We disclose a direct approach to the diastereoselective synthesis of phosphorus substituted N-acylaziridines based on a one-pot ZnCl2-catalyzed Joullié–Ugi three-component reaction of phosphorylated 2H-azirines, carboxylic acids and isocyanides. Hence, this robust protocol offers rapid access to an array of N-acylaziridines in moderate-to-good yields and up to 98:2 dr for substrates over a wide scope. The relevance of this synthetic methodology was achieved via a gram-scale reaction and the further derivatization of the nitrogen-containing three-membered heterocycle. The diastereo- and regioselective ring expansion of the obtained N-acylaziridines to oxazole derivatives was accomplished in the presence of BF3·OEt2 as an efficient Lewid acid catalyst. [ABSTRACT FROM AUTHOR]

The Sc(OTf)3-catalyzed dearomative [5+1] annulations between readily available 3-aminophenols and O-alkyl ortho-oxybenzaldehydes were developed for synthesis of spiro[chromane-3,1′-cyclohexane]-2′,4′-dien-6′-ones. The "two-birds-with-one-stone" strategy was disclosed by the dearomatization of phenols and direct α-C(sp3)–H bond functionalization of oxygen through cascade condensation/[1,5]-hydride transfer/dearomative-cyclization process. In addition, the antifungal activity assay and derivatizations of products were conducted to further enrich the utility of the structure. [ABSTRACT FROM AUTHOR]

Asymmetric hydrogenation (AH) of tetrasubstituted olefins generating two stereocenters is still an open topic. There are only a few reports on the AH of tetrasubstituted olefins with conjugated functional groups, while this process can create useful intermediates for the subsequent elaboration of relevant end products. Most of the tetrasubstituted olefins successfully submitted to AH belong to a small number of functional classes; remarkably, the AH of tetrasubstituted acyclic enones still represents an unsolved challenge. Herein, we disclose a class of air‐stable Ir−P,N catalysts, prepared in three steps from commercially available amino alcohols, that can hydrogenate, in minutes, a wide range of electronically and sterically diverse acyclic tetrasubstituted enones (including exocyclic ones) with high yields and high enantioselectivities. The factors responsible for the excellent selectivities were elucidated by combining deuterogenation experiments and theoretical calculations. The calculations indicated that the reduction follows an IrI/IrIII mechanism, in which enantioselectivity is controlled in the first migratory insertion of the hydride to the most electrophilic olefinic Cβ and the formation of the hydrogenated product via reductive elimination takes place prior to the coordination of dihydrogen and the subsequent oxidative addition. The potential of the new catalytic systems is demonstrated by the derivatization of hydrogenation products. [ABSTRACT FROM AUTHOR]

Asymmetric hydrogenation (AH) of tetrasubstituted olefins generating two stereocenters is still an open topic. There are only a few reports on the AH of tetrasubstituted olefins with conjugated functional groups, while this process can create useful intermediates for the subsequent elaboration of relevant end products. Most of the tetrasubstituted olefins successfully submitted to AH belong to a small number of functional classes; remarkably, the AH of tetrasubstituted acyclic enones still represents an unsolved challenge. Herein, we disclose a class of air‐stable Ir−P,N catalysts, prepared in three steps from commercially available amino alcohols, that can hydrogenate, in minutes, a wide range of electronically and sterically diverse acyclic tetrasubstituted enones (including exocyclic ones) with high yields and high enantioselectivities. The factors responsible for the excellent selectivities were elucidated by combining deuterogenation experiments and theoretical calculations. The calculations indicated that the reduction follows an IrI/IrIII mechanism, in which enantioselectivity is controlled in the first migratory insertion of the hydride to the most electrophilic olefinic Cβ and the formation of the hydrogenated product via reductive elimination takes place prior to the coordination of dihydrogen and the subsequent oxidative addition. The potential of the new catalytic systems is demonstrated by the derivatization of hydrogenation products. [ABSTRACT FROM AUTHOR]

A cobalt‐catalyzed 1,2‐regioselective dicarbofunctionalization of silylated 1,3‐dienes with functionalized solid organozinc pivalates and alkyl bromides is disclosed, thus affording the alkylarylated and dialkylated silanes in a regioselective manifold. Herein, regioselectivity is steered by steric hindrance of the bulky silyl groups, which could prohibit the formation of the flexible π‐allylcobalt intermediate. Furthermore, derivatizations of the resulting products and modifications of bioactive molecules demonstrate the synthetical utility of our method. [ABSTRACT FROM AUTHOR]

A palladium‐catalyzed synthesis of 2‐SF5‐indenols has been developed by reacting commercially available boronic acid derivatives and readily accessible SF5‐alkynes. The present methodology is fully regioselective thanks to the intrinsic polarization of SF5‐alkynes. A selection of downstream functionalizations has been performed to highlight the versatility of 2‐SF5‐indenols and indenones as platforms for the design of more complex SF5‐containing molecules. [ABSTRACT FROM AUTHOR]

A palladium‐catalyzed synthesis of 2‐SF5‐indenols has been developed by reacting commercially available boronic acid derivatives and readily accessible SF5‐alkynes. The present methodology is fully regioselective thanks to the intrinsic polarization of SF5‐alkynes. A selection of downstream functionalizations has been performed to highlight the versatility of 2‐SF5‐indenols and indenones as platforms for the design of more complex SF5‐containing molecules. [ABSTRACT FROM AUTHOR]

Carboxylic acids (CAs) are key players in human and animal metabolism. As they are hardly retained under reversed-phase liquid chromatography (RP-LC) conditions in their native form, derivatization is an option to make them accessible to RP-LC and simultaneously increase their response for mass spectrometric detection. In this work, two RP-LC tandem mass spectrometry-based methods using aniline or 3-nitrophenylhydrazine (3-NPH) as derivatization agents were compared with respect to several factors including completeness of derivatization, apparent recoveries (RAs) in both cow feces and ruminal fluid, and concentrations obtained in feces and ruminal fluid of cows. Anion exchange chromatography coupled to high-resolution mass spectrometry (AIC-HR-MS) served as reference method. Derivatization efficiencies were close to 100% for 3-NPH derivatization but variable (20–100%) and different in solvent solutions and matrix extracts for aniline derivatization. Likewise, average RAs of 13C-labeled short-chain fatty acids as internal standards were around 100% for 3-NPH derivatization but only 45% for aniline derivatization. Quantification of CAs in feces and ruminal fluid of cows initially fed a forage-only diet and then transitioned to a 65% high-grain diet which yielded similar concentrations for 3-NPH derivatization and AIC-HR-MS, but concentrations determined by aniline derivatization were on average five times lower. For these reasons, derivatization with aniline is not recommended for the quantitative analysis of CAs in animal samples. [ABSTRACT FROM AUTHOR]

Applying solutions of a matrix or derivatization agent via microdroplets is a common sample preparation technique for matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) experiments. Mobilized nebulizer sprayers are commonly used to create a homogeneous matrix or reagent layer across large surfaces. Electrospray devices have also been used to produce microdroplets for the same purpose but are rarely used for large tissues due to their immobility. Herein, we present a movable electrospray device that can be used for large tissue sample preparation through a simple modification to an automatic commercial nebulizer device. As demonstrated for on-tissue chemical derivatization (OTCD) with Girard's reagent T using a mimetic tissue model, the sprayer has the additional benefit of being able to investigate reaction acceleration in OTCD when comparing electrostatically charged spray to electrostatically neutral spray. Finally, MALDI-MSI of fatty aldehydes is successfully demonstrated in rat brain tissues using this device for both OTCD and matrix application. [ABSTRACT FROM AUTHOR]

We report herein an unprecedented enantioselective (4+4) cycloaddition of simple 1,3‐dienes with azadienes for the construction of fused eight‐membered N‐heterocycles. In this transformation, the π‐Lewis basic Pd(0) catalyst achieves activation of 1,3‐dienes to induce nucleophilic addition to azadienes followed by ring cyclization via a selective terminal allylic substitution. Furthermore, highly efficient and diastereoselective derivatizations of the eight‐membered rings provide a facile access to diverse enantiopure fused tetra‐ to hexacyclic compounds with potential application in medicinal chemistry. [ABSTRACT FROM AUTHOR]