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A base-catalyzed O-phosphorylation of aldehyde/ketone with RP-menthyl phenylphosphinate afforded phosphonates. The mechanism was proposed as an intermolecular SN@P reaction of α-hydroxy phosphinate. In an intermediate, the C–P bond was transferred from the equatorial to axial position via Berry pseudorotation, and then was cleaved with the leaving of a carbon anion. The P-retention and C-racemization could be satisfactorily explained by the mechanism. [ABSTRACT FROM AUTHOR]

Photobromination of toluene derivatives using blue LED (454 nm) or UV LEDs (365, 385, 395 nm) with aqueous HBr and NaOCl·5H2O in trifluoromethyl benzene afforded the corresponding benzoic acids derivatives. The intermediates were (dibromomethyl)benzene derivatives, isolated in a nitrogen atmosphere. The dibromomethyl benzene derivatives afforded the corresponding aldehydes. After the reaction with HBr, the aqueous layer could be recovered and reused. [ABSTRACT FROM AUTHOR]

AbstractAn efficient synthesis of new aminodimethyl(methylsulfonyl)dihydropyrido[2,3-d]pyrimidinedione derivatives via the three components reaction of 2-methanesulfonylacetonitrile, 1,3-dimethyl-6-amino-uracil, and aromatic aldehydes in the presence of [HO-(CH2)2-NH2][CH3CO2H] and Fe3O4@SiO2@[O-(CH2)2-NH2][CH3CO2H] as novel heterogeneous magnetic nanocatalyst was described. The Fe3O4@SiO2@[O-(CH2)2-NH2][CH3CO2H] as nanocatalyst can be easily separated from the reaction mixture by an external magnet, recycled, and reused several times without any significant decrease in catalytic activity. These methods showed several advantages, including high yields, easy operation, and environment-friendly protocols. [ABSTRACT FROM AUTHOR]

First, a Brønsted acid ionic liquid (BAIL) in the role of a double acid-base called 1,3-n-propyl-bipyridinium bisulfonic acid-ditrifluoroacetate (PBPBSDT) was produced, and its skeleton was determined via TGA, mass, 13C NMR, 19F NMR, 1H NMR and FT-IR data. Further, it was successfully applied in the preparation of dibenzo-chromeno-phenazine-dione derivatives (1a-12a, 9–15 min, 90–98%) via one-pot multicomponent domino reaction among 2 mmol 2-hydroxynaphthalene-1,4-dione, 1 mmol benzene-1,2-diamine, and 1 mmol aldehydes under optimal conditions (5 mol% of PBPBSDT, solvent-free, 60 °C). The proper reproducibility of the PBPBSDT homogeneous catalyst (5 times), solvent-free medium, reasonable TON (Turnover Number) and TOF (Turnover Frequency) numbers, the non-metallic framework of the catalyst, and the formation of C-N, C = N, C-C, C = C, C-O bonds in a single operation are the distinct advantages of this protocol. [ABSTRACT FROM AUTHOR]

Inherently chiral calix[4]arenes represent a unique type of chiral molecules with significant applications, yet their catalytic enantioselective synthesis remains largely underexplored. We report herein the catalytic enantioselective synthesis of inherently chiral calix[4]arenes through the sequential organocatalyzed enantioselective Povarov reaction and aromatizations. The chiral phosphoric acid catalyzed three‐component Povarov reaction involving amino group‐substituted calix[4]arenes, aldehydes and (di)enamides desymmetrized the prochiral calix[4]arene substrates, which was followed by various aromatization methods, resulting in a diverse array of novel quinoline‐containing calix[4]arenes with good yields and high enantioselectivities (up to 75 % yield, 99 % ee). The large‐scale enantioselective synthesis and diverse derivatizations of the chiral calix[4]arene products highlight the value of this method. Furthermore, preliminary exploration into their photophysical and chiroptical properties demonstrate the potential applications of these novel calix[4]arene molecules. [ABSTRACT FROM AUTHOR]

This article is a continuation of our previous research on the catalytic capability of a chiral copper complex based on commercially available (S)-2-aminomethylpyrrolidine and 3,5-di-tert-butylsalicylaldehyde with various counter-anions in the asymmetric Henry reaction. Our findings indicate that depending on the type of base used, chiral nitroalcohols with yields up to 98% and ee values up to 77%, as well as β-nitrostyrenes with yields up to 88%, can be produced. Additionally, it has been found that the outcome of the reaction and the catalytic properties of copper (II) complexes (S)-Cu1 and (S)-Cu2 are influenced by the structure of the aldehyde used. [ABSTRACT FROM AUTHOR]

The present article describes the successful performance of crossed aldol reactions of the CF3-containing pseudo-C2 symmetric cyclic imide with various aldehydes. The utilization of HMPA as an additive attained the preferential formation of the anti-products in good to excellent yields, which contrasts with our previous method without this additive, proceeding to furnish the corresponding syn-isomers. The effective participation of ketones and α,β-unsaturated carbonyl compounds in reactions with this imide was also demonstrated to expand the application of this imide. [ABSTRACT FROM AUTHOR]

Within this study, we report a simple two-step process for the synthesis of perfluoroalkylated pyrazoles from aliphatic aldehydes. In the photocatalytic first step, the aldehydes are transformed into the corresponding perfluoroalkylated enals, which then undergo nucleophilic attack by hydrazine and subsequent ring closure, providing the fluorinated 3,4-substituted pyrazole products in a 64–84% yield. Using triphenylphosphine and imidazolidinone as organocatalysts, the method is operationally simple and omits heavy metal-containing waste. [ABSTRACT FROM AUTHOR]

Quinazolines and their derivatives occur in various natural products and pharmaceuticals, and thus, various methods of synthesizing quinazolines have been explored. They have traditionally been synthesized via two‐component reactions, but these strategies often suffer from the unavailability of the starting materials and limited substrate scopes. To overcome these problems, three‐component reactions using additional N sources were developed. Aldehydes were initially used in these reactions, but alcohols are greener and less toxic than aldehydes. However, the previously reported methods involving the use of alcohols require the utilization of transition metal catalysts, ultrahigh temperatures, and extended durations. Thus, an efficient, practical method of synthesizing quinazolines using alcohol is desirable. A facile one‐pot three‐component method of synthesizing quinazolines utilizing alcohols, 2‐aminobenzoketones, and ammonium acetate is reported for the first time, using active MnO2 and tert‐butyl hydrogen peroxide (TBHP) as synergistic oxidants. MnO2 and TBHP play dual roles: First, they oxidize the alcohol to the aldehyde and then facilitate the transformation of the intermediate into the product. During alcohol oxidation, the synergistic effect of MnO2 and TBHP is particularly evident. The aldehydes generated in situ via alcohol oxidation undergo immediate subsequent reactions, thereby minimizing their volatilization and side reactions, such as oxidation and polymerization. [ABSTRACT FROM AUTHOR]

The new type of the four‐component tandem Knoevenagel–Michael reaction was discovered: the transformation of arylaldehydes, N,N′‐dimethylbarbituric acid, malononitrile, and morpholine in alcohols and other organic solvents without any other additives at ambient temperature resulted in the selective formation of a new substituted unsymmetrical ionic scaffold with two pharmacology‐active heterocyclic rings. This new four‐component reaction is a simple and efficient route to a previously unknown substituted ionic unsymmetrical scaffold containing N,N′‐dimethylbarbituric acid and morpholine. These ionic scaffolds are promising for various biomedical applications, for example, as anticonvulsants and anti‐inflammatory drugs, as well as anti‐AIDS agents. In this research, we also accomplished the efficient cyclization of morpholin‐4‐ium 5‐(2,2‐dicya‐no‐1‐arylethyl)‐1,3‐dimethyl‐2,6‐di‐oxo‐1,2,3,6‐tetrahydro‐pyrimidin‐4‐olates by the action of NBS–NaOAc system, with the formation of 5,7‐dimethyl‐4,6,8‐trioxo‐2‐aryl‐5,7‐diazaspiro[2.5]octane‐1,1‐dicarbonitriles in 83%–98% yields. In the final stage of our research, direct one‐pot multicomponent transformation of benzaldehydes, N,N′‐dimethylbarbituric acid, and malononitrile into spirobarbituric cyclopropanes was accomplished in 75%–97% yields. The spiro‐barbituric cyclopropanes are potentially active as remedies against various inflammatory, infectious, immunological, or malignant diseases. [ABSTRACT FROM AUTHOR]

9-Carbon aldehydes such as (2E)-nonenal, (3Z)-nonenal, and (2E,6Z)-nonadienal are important melon and cucumber fragrance compounds. Currently, these molecules are produced either synthetically, which faces consumer aversion, or through biotransformation using plant-extracted enzymes, which is costly and inefficient. In this study, we constructed a Saccharomyces cerevisiae platform for the whole cell biotransformation of polyunsaturated fatty acids (PUFAs) to 9-carbon aldehydes. Heterologous expression of lipoxygenase (LOX) from Nicotiana benthamiana and hydroperoxide lyase (HPL) from Cucumis melo (melon) in S. cerevisiae enabled the production of (2E)-nonenal from readily available polyunsaturated fatty acid substrates. A 5.5-fold increase in (2E)-nonenal titer was then achieved utilizing genetic and reaction condition enhancement strategies. The highest titer of (2E)-nonenal was more than 0.11 mM, with about 9% yield. This platform can potentially be used to produce a variety of other aldehyde products by customizing with LOX and HPL enzymes of different regio-selectivities. Key points: • Establishment of a S. cerevisiae whole-cell biotransformation platform for cost-efficient, high-yield conversion of PUFAs into high value 9-carbon aldehyde compounds • 5.5-Fold improvement of (2E)-nonenal titer to > 0.11 mM achieved by enhancing reaction conditions and gene expression levels of LOX and HPL [ABSTRACT FROM AUTHOR]

The present article provides an overview of our work related to cyclization reactions of nitro-substituted electrophilic building blocks with various nucleophiles. As electrophiles, we used nitro-substituted benzoylacetones, 3-ethoxy-2-nitro-2-en-1-ones, 2-nitrobenzoyl chlorides, 4-chloro-3-nitrocoumarin, 2-nitromalonic aldehyde, 3-nitrochromone and 1-(2-chloro-5-nitrophenyl)prop-2-yn-1-ones. As nucleophiles, 1,3-dicarbonyl compounds, 1,3-bis(silyloxy)-1,3-butadienes, (heterocyclic) enamines, hydroxylamine, hydrazines, amines and amino esters were employed. The products include a variety of nitro-substituted carbo- and heterocycles that are not readily available by other methods. The electron-withdrawing nitro group can be easily transformed into an electron-donating amino group which is not only pharmacologically relevant, but can also act as a nucleophile in inter- and intramolecular reactions with electrophiles, such as aldehydes, and can be converted into other functional groups. The nitro group has the capacity to activate compounds for regioselective palladium-catalyzed CH-arylation reactions. Inter- and intramolecular CH arylations of nitro-substituted heterocyclic building blocks, such as 4-nitropyrazoles, 4-nitroimidazoles, 2-nitroindole and nitro-substituted purine analogues, allow for a convenient diversity-oriented approach to the corresponding arylated products. In addition, the nitro group can act as a leaving group in SN Ar reactions. Various fused benzofuro[3,2- b ]pyridines were prepared by intramolecular SN Ar reactions of 2-(hydroxyphenyl)-3-nitropyridines. 1 Introduction 2 Cyclizations of 1,3-Bis(silyloxy)-1,3-butadienes 3 Cyclizations of Heterocyclic Enamines 4 Reactions of Simple Nitro-Substituted Heterocycles 5 Hydroamination Reactions of Alkynes 6 Miscellaneous 7 Conclusions [ABSTRACT FROM AUTHOR]

In this study, oleogels were produced with the emulsion template method utilizing seven phenolic aldehyde fragrances (PAFs) crosslinked with chitosan, and the physical and chemical characteristics of oleogels prepared by different crosslinking factors were comparatively investigated. XRD and ATR-FTIR results showed that chitosan was crosslinked with the PAFs to generate Schiff bases and that the Schiff base reaction was the main contributing factor to the construction of the oleogels. Macroscopic characterization showed that all the oleogels had good Oil binding capacity (> 90%) and high gel hardness (> 55.46 g). The rheological properties showed that all the oleogels had high thermal stability and gel strength (G'>G"), as well as good thixotropic recovery (among them, CS-ISA had the largest thixotropic recovery of 24.05%), which indicated the elasticity and structural stability of the gel network formed by crosslinking of PAF and chitosan.Additionally, lower oxidation rates were observed for the peroxide value (POV) and thiobarbituric acid reactive substance (TBARS) values of all oleogels in accelerated oxidation experiments, all indicating good oxidative stability. [ABSTRACT FROM AUTHOR]

The volatile components of Stropharia rugosoannulata and Tricholoma lobayense were analyzed by mass spectrometry, and the relative contents of each component were determined by the internal standard method. In Stropharia rugosoannulata, 58 volatile components were identified, including 10 alcohols, 14 esters, 9 aldehydes, 5 ketones, 1 phenol, 3 alkanes, 4 amines, 5 acids, 1 furan, 1 pyrazine, 1 olefin, 1 oxime, 1 pyrazole, and 2 other components. Among them, the most abundant volatile component was hexanal (1655.40 ng/g), followed by pentanoic acid (1503.10 ng/g) and phenylethyl alcohol (1215.94 ng/g). In Tricholoma lobayense, 68 volatile components were identified, including 17 aldehydes, 11 ketones, 8 acids, 10 esters, 5 alcohols, 1 phenol, 2 furans, 4 alkanes, 1 alkene, 1 oxime, 1 pyrazole, 1 amine, and 6 other components. Among them, the most abundant volatile component was benzaldehyde (2190.67 ng/g), followed by hexanal (1708.81 ng/g) and furan, 2-pentyl- (838.45 ng/g). There were 21 common volatile components between the two different edible fungi, including 7 aldehydes, 5 esters, 3 ketones, 2 alcohols, 2 acids, 1 oxime, and 1 furan. [ABSTRACT FROM AUTHOR]

The search for novel synthetic tools to prepare industrial chemicals in a safer and greener manner is a continuing challenge in synthetic chemistry. In this manuscript, we report the discovery, characterization, and synthetic potential of two novel aryl-alcohol oxidases from bacteria which are able to oxidize a variety of aliphatic and aromatic alcohols with efficiencies up to 4970 min−1 mM−1. Both enzymes have shown a reasonable thermostability (thermal melting temperature values of 50.9 and 48.6 °C for ShAAO and SdAAO, respectively). Crystal structures revealed an unusual wide-open entrance to the active-site pockets compared to that previously described for traditional fungal aryl-alcohol oxidases, which could be associated with differences observed in substrate scope, catalytic efficiency, and other functional properties. Preparative-scale reactions and the ability to operate at high substrate loadings also demonstrate the potential of these enzymes in synthetic chemistry with total turnover numbers > 38000. Moreover, their availability as soluble and active recombinant proteins enabled their use as cell-free extracts which further highlights their potential for the large-scale production of carbonyl compounds. Key points: • Identification and characterization of two novel bacterial aryl-alcohol oxidases • Crystal structures reveal wide-open active-site pockets, impacting substrate scope • Total turnover numbers and cell-free extracts demonstrate the synthetic potential [ABSTRACT FROM AUTHOR]

ABSTRACT CuI–Zn(OAc)2 catalyzed a new, fast, solvent‐free strategy for the synthesis of quinazolin‐4(3H)‐ones via selective scission of CC bond of the 1,3‐diketone (both cyclic and acyclic) and β‐ketoester was achieved under microwave irradiation. In contrast to the frequently applied synthetic strategy that involves cyclization‐oxidation sequence of anthranilamides (2‐aminobenzamides) with various aldehydes or benzyl alcohols, here, anthranilamide reacts with β‐ketoester/1,3‐diketo compounds in presence of CuI‐Zn(OAc)2 catalyst to form quinazolin‐4(3H)‐ones scaffold through an uncommon CC bond cleavage under solvent‐free mild conditions with excellent yields. Besides, this method displays its capacity for gram‐scale reactions. [ABSTRACT FROM AUTHOR]

In this research various pyridazino[1,2‐a]indazole and 1H‐indazolo[1,2‐b]phthalazine and 1H‐indazolo[1,2‐b]phthalazine derivatives were produced with a high yield via a multi‐component reaction of dimedone, aldehyde, hydrazine and anhydride compounds in the presence of a novel DABCO‐Saccharin acetate ([DABCOH][Sac‐CH3CO2]) ionic liquid under microwave irradiation. The applied method for producing these heterocyclic compounds demonstrated a number of desirable traits, including quick reactions, high yields of the final product, and straightforward separation of the product and catalyst from the reaction mixture. [ABSTRACT FROM AUTHOR]

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Copyright of Food & Fermentation Industries is the property of Food & Fermentation Industries and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We have developed a TfOH-catalyzed, highly efficient protocol for the synthesis of biologically active β-acylamino ketones from aldehyde, ketone, and nitrile by avoiding the use of acetyl chloride. The reaction proceeds through a sequential aldol reaction followed by a nucleophilic attack of nitrile and hydrolysis of nitrile in one pot. The attractive features of this tandem process are mild reaction conditions, high atom economy, broad substrate scope with 51–87% yield, gram-scale reaction, and ease of operation. [ABSTRACT FROM AUTHOR]

Herein, we report a metal-free, base-promoted route for the synthesis of hybrid molecular scaffolds in which various 1,3-diones and 1,2,4-triazoles are linked by a benzyl bridge. This three-component, one-pot reaction was accomplished by first treating 4-hydroxycoumarin, trans-β-nitrostyrene, and aldehyde hydrazone in the presence of sodium carbonate. Further, this protocol was successfully expanded to other 1,3-diones, such as dimedone and 4-hydroxy-2-quinolone. A broad substrate scope, mild reaction conditions, and the metal and ligand/additive-free approach are the prominent features of this strategy. [ABSTRACT FROM AUTHOR]

A two‐component low‐molecular‐weight gelator (LMWG) formed from a modified amino acid and an aldehyde was formulated with active pharmaceutical ingredients (APIs). Basic APIs (propranolol, atropine) can be mixed with the LMWG prior to gel assembly while acidic APIs (naproxen, rosuvastatin) inhibit assembly by disrupting the LMWG imine bond and were loaded by diffusion after gel assembly. For diffusion‐loaded gels, the API in the liquid‐like phase was rapidly released, with the remainder, interacting with gel fibres, retained in the gel. Rosuvastatin release was particularly low with Saturation Transfer Difference (STD) NMR indicating interactions between the aromatic ring and the self‐assembled gel network. Propranolol also interacted with the gel via its aromatic unit, and its release led to gel erosion. Using agarose as a polymer gelator additive reinforced the gel, restricting erosion. In contrast, atropine was readily released over a period of hours ‐ it is primarily in the liquid‐like phase with STD NMR indicating no interactions with the gel network. The atropine‐loaded gel retained its thixotropic properties. Overall, APIs must be carefully chosen to optimise formulation/release. Of the APIs investigated, atropine has most potential for further development. Atropine has applications in treating myopia, and our results suggest potential ophthalmic applications of supramolecular gels. [ABSTRACT FROM AUTHOR]

With the interest and knowing the importance of ferrocenyl conjugates, a direct amidation of ferrocenyl aldehyde has been developed under feasible conditions. Varieties of amines has been oxidatively coupled with ferrocene aldehyde in the presence of highly economical and robustly stable iron chalcogenide ironcarbonyl clusters [Fe3E2(CO)9, E= S, Se, and Te] and TBHP. The reaction worked in greener solvent water at a moderate temperature of 70 °C and the ferrocenyl‐amides in just 30 minutes. All the varieties of amines were found to be well tolerated for the present method, and due to the high medicinal importance of ferrocenyl‐amides, sole focus of this report was concentrates on the synthesis of various new ferrocenyl‐amides in good to excellent amounts. [ABSTRACT FROM AUTHOR]

Selenoxide syn elimination is a widely used method for the synthesis of alkenes because it proceeds under exceptionally mild conditions, typically with excellent regio- and stereoselectivity. Surprisingly, hetero-selenoxide eliminations, where one or both olefinic carbon atoms are replaced with heteroatoms, have been little investigated, and their selenonyl counterparts even less so. A variety of such reactions, where the heteroatoms included combinations of O, N and S, as well as C, were investigated computationally. Selenoxides typically have lower activation energies and are slightly endothermic, while the corresponding selenones display higher activation energies and are exothermic in the gas state. The results are consistent with concerted, five-centre processes, leading to the formation of dioxygen, aldehydes, diazenes and imines from seleninyl or selenonyl peroxides, esters, hydrazines and amines, respectively. The more acidic selenenyl hydrodisulfide analogue undergoes proton transfer to the basic selenoxide oxygen atom instead of concerted elimination, resulting in the formation of a zwitterion. However, the formation of the corresponding selenonyl zwitterion is disfavoured compared to concerted syn elimination. The effects of solvents were also computed along with changes in enthalpy, entropy and free energy. Solvent effects were variable, while free energy calculations indicated overall ΔG values ranging between 3.60 and −32.12 kcal mol−1 for the syn eliminations of methyl methanethioseleninate and methaneperoxyselenonic acid, respectively. These computations suggest that the olefin-forming selenoxide syn elimination may be more general than currently understood and that replacement of the two carbon atoms with heteroatoms can lead to viable processes. [ABSTRACT FROM AUTHOR]

ABSTRACT Treatment of Ru3(CO)12 with salicylaldimine ligands [ArNCH(3‐tBuC6H3OH) [ArC6H5 (L1H); 4‐OMeC6H4 (L2H); 4‐MeC6H4 (L3H); 2,4,6‐Me3C6H2 (L4H); 4‐ClC6H4 (L5H); 4‐BrC6H4 (L6H)] in refluxing toluene afforded six bis‐ligand mononuclear ruthenium carbonyl complexes [ArNCH(3‐tBuC6H3O)]2Ru(CO)2 1a–1f in good yields. All of the Ru(II) complexes were characterized using IR, NMR, and elemental analysis. The molecular structures of complexes 1a, 1b, 1e, and 1f were further confirmed through X‐ray diffraction analysis. Additionally, the catalytic performance of these complexes was investigated in the oxidation of olefins to aldehydes, using TBHP as the oxidant in refluxing trichloromethane. With 1.0 mol% catalyst loading, these ruthenium complexes displayed high reactivity and good functional‐group compatibility, selectivity providing the corresponding oxidation product aldehydes in 73%–94% yields. [ABSTRACT FROM AUTHOR]

Schiff bases are a class of synthetic compounds that form when primary amines combine with aldehydes or ketones. These compounds are incredibly important across various fields, such as biology, catalysis, and optics, due to their diverse features. One notable aspect is their ability to form complexes with transition metals, which opens up a wide range of potential uses, particularly in human systems. In the human body, Schiff base metal complexes display a range of biological actions, including antibacterial, antifungal, anticancer, and antimalarial properties. The versatility of Schiff bases in reacting with different transition metals gives these complexes intriguing potential for addressing biological issues and treating diseases. This article explores various examples of Schiff bases, metal complexes, and their associated ligands, highlighting their usefulness in a variety of biological applications. The potential of Schiff base metal complexes as valuable agents in resolving medical difficulties and advancing biomedical research is emphasized. [ABSTRACT FROM AUTHOR]

The substituted tetrahydrofuran core is a structural motif in many biologically active and natural compounds. However, the scarcity of enantioselective methods developed towards its synthesis makes this field challenging and attractive to explore. Herein, the first Brønsted‐base catalyzed enantioselective (3+2) annulation of donor‐acceptor cyclopropanes with aldehydes and ketones affording enantioenriched 2,3,5‐substituted tetrahydrofurans is reported. The reaction concept is based on activation of racemic β‐cyclopropyl ketones by a chiral bifunctional Brønsted base which catalyzes the (3+2) annulation for a range of aldehydes and ketones. For aldehydes, the annulation furnished tetrahydrofurans in excellent yield, good diastereoselectivity and with excellent enantioselectivity up to >99 % ee. Surprisingly, aromatic aldehydes afforded the cis‐2,5‐substituted tetrahydrofurans as the major diastereoisomer, while for aliphatic aldehydes the trans‐cycloadduct was favored. The reaction also proceeds well for ketones affording spiro tetrahydrofurans in excellent yields and enantioselectivities (up to 99 % ee). Hammett studies have been conducted to elucidate the influence of the electronic nature of benzaldehydes on the stereoselectivity. Based on the diastereochemical outcome for the aldehydes, two reaction paths for aromatic and aliphatic aldehydes are proposed. Finally, two diastereoselective synthetic transformations have been conducted to demonstrate the synthetic potential of the obtained products. [ABSTRACT FROM AUTHOR]

An efficient and eco-friendly procedure was developed for the synthesis of N -aryl-2-((3-aryl-1,2,4-oxadiazol-5-yl)thio)acetamides from N -aryl-2-thiocyanatoacetamides and substituted N -hydroxybenzimidoyl chlorides that were prepared easily from the commercially available anilines and aryl aldehydes, respectively. The N -aryl-2-thiocyanatoacetamide acts as a dipolarophile while the nitrile oxide formed in situ from substituted N -hydroxybenzimidoyl chloride acts as the nucleophilic partner in a 1,3-dipolar cycloaddition reaction mediated by triethylamine base in ethanol medium. The procedure affords excellent yields of desired products containing electron-withdrawing and electron-donating groups on the aromatic rings, in short reaction time with ease of operation. The procedure for the synthesis of scaffolds that are potentially valuable for their biological properties also offers the possibility of scale-up to higher quantities. [ABSTRACT FROM AUTHOR]

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Here we report a transition metal– and oxidant–free annulation cascade method for the synthesis of chromeno–isoxazoles. The annulation reaction involves easily accessible starting materials, 3‐nitro‐2H‐chromene and α‐chloro aldehyde, yielding the structurally intriguing framework, chromeno[3,4‐c]isoxazoles employed by tripotassium phosphate as a base. The isoxazole ring construction over the 2H–chromene unit is believed to occur via a series of multiple reaction sequences. Here, the enolate generation/Michael addition/C−Cl bond cleavage/oxy–anionic addition to reactive tethered‐aldehyde/deformylation via retro–C−C and N−O bond cleavages are the most possible sequences which furnish the desired end–product in good chemical yields. The multiple reaction sequences occur in one‐pot at mild conditions, supported by experimental results and a few control experiments including DFT studies. This process exhibits a broad substrates scope illustrating good functional group compatibility towards both the nitrochromenes and aldehydes, and thus prove to be a general and efficient protocol for the synthesis of chromeno[3,4–c]isoxazoles. Overall, the use of nitrochromene as the limiting reagent, noteworthy functional group tolerance, scalability including great applications like chiral pool strategy towards the synthesis of enantioenriched chromeno‐isoxazole are the additional features. [ABSTRACT FROM AUTHOR]

The selective and controllable functionalization of unreactive C(sp3)–H bonds under mild conditions is a highly desirable yet challenging goal in both organic synthesis and pharmaceutical industry. Herein, we report an unprecedented visible-light mediated metal- and oxidant-free carbonylation of both benzylic and allylic C–H bonds with H2O. The synergistic combination of an organophotocatalyst 4CzIPN and a thiol enables the transformation of diverse arrays of benzylic and allylic C–H bonds into carbonyls in moderate to excellent yields with good functional group compatibility. Moreover, the oxidation of amines to aldehydes has also been realized by this protocol. Mechanistically, an oxidative radical-polar crossover (ORPC) process affords an alcohol intermediate, which then undergoes another ORPC process to furnish the carbonyl product. [ABSTRACT FROM AUTHOR]

A photocatalytic trifluoromethylation/cyclization reaction of N-allyl and N-homoallyl aldehyde hydrazones with trifluoromethyl thianthrenium triflate was developed for the synthesis of trifluoromethylated dihydropyrazoles and tetrahydropyridazines. Besides, PhI(O2CCHF2)2 was employed to realize the construction of difluoromethylated dihydropyrazoles and tetrahydropyridazines. These protocols exhibit a broad substrate scope and good functional group tolerance. [ABSTRACT FROM AUTHOR]

Poria cocos (Schw.) wolf (P. cocos) is an important medicinal material with both therapeutic and edible properties. This study investigated volatile constituents, amino acids, proteins, polysaccharides, triterpenoid ingredients, and alcohol-soluble extracts on P. cocos during eight drying processes. A total of 47 volatile components were found and identified; the main volatile components of shade drying (SD) and hot-air drying at 50 °C (HD50) were esters and alcohols, while for drying in hot air at 60 °C~100 °C (△ = 10 °C) and infrared drying (ID), the main compounds were aldehydes and hydrocarbons. The amino acids in P. cocos remained the same when dried with various methods. Compared with SD samples, with the temperature increase, the content of amino acids showed a trend of first decreasing and then increasing, while the content trend of proteins was the opposite. The HD70 samples had the highest content of polysaccharide, triterpenoid ingredients, alcohol-soluble extracts, and antioxidant activity. Furthermore, volatile compounds showed a correlation between non-volatile constituents. This research provides evidence that the aroma, active components, and activity of P. cocos were affected by the drying method. [ABSTRACT FROM AUTHOR]

Electronic nicotine delivery systems (ENDS) aerosol exposures can induce endothelial dysfunction (ED) in healthy young humans and animals. Thermal degradation of ENDS solvents, propylene glycol, and vegetable glycerin (PG: VG), generates abundant formaldehyde (FA) and other carbonyls. Because FA can activate the transient receptor potential ankyrin-1 (TRPA1) sensor, we hypothesized that FA in ENDS aerosols provokes TRPA1-mediated changes that include ED and "respiratory braking"—biomarkers of harm. To test this, wild-type (WT) and TRPA1-null mice were exposed by inhalation to either filtered air, PG: VG-derived aerosol, or FA (5 ppm). Short-term exposures to PG: VG and FA-induced ED in female WT but not in female TRPA1-null mice. Moreover, acute exposures to PG: VG and FA stimulated respiratory braking in WT but not in TRPA1-null female mice. Urinary metabolites of FA (ie, N - 1,3-thiazolidine-4-carboxylic acid, TCA; N - 1,3-thiazolidine-4-carbonyl glycine, TCG) and monoamines were measured by LC-MS/MS. PG: VG and FA exposures significantly increased urinary excretion of both TCA and TCG in both WT and TRPA1-null mice. To confirm that inhaled FA directly contributed to urinary TCA, mice were exposed to isotopic 13C-FA gas (1 ppm, 6 h). 13C-FA exposure significantly increased the urine level of 13C-TCA in the early collection (0 to 3 h) supporting a direct relationship between inhaled FA and TCA. Collectively, these data suggest that ENDS use may increase CVD risk dependent on FA, TRPA1, and catecholamines, yet independently of either nicotine or flavorants. This study supports that levels of FA in ENDS-derived aerosols should be lowered to mitigate CVD risk in people who use ENDS. [ABSTRACT FROM AUTHOR]

SUMMARY: Among the three active aldehyde oxidases in Arabidopsis thaliana leaves (AAO1‐3), AAO3, which catalyzes the oxidation of abscisic‐aldehyde to abscisic‐acid, was shown recently to function as a reactive aldehyde detoxifier. Notably, aao2KO mutants exhibited less senescence symptoms and lower aldehyde accumulation, such as acrolein, benzaldehyde, and 4‐hydroxyl‐2‐nonenal (HNE) than in wild‐type leaves exposed to UV‐C or Rose‐Bengal. The effect of AAO2 expression absence on aldehyde detoxification by AAO3 and/or AAO1 was studied by comparing the response of wild‐type plants to the response of single‐functioning aao1 mutant (aao1S), aao2KO mutants, and single‐functioning aao3 mutants (aao3Ss). Notably, aao3Ss exhibited similar aldehyde accumulation and chlorophyll content to aao2KO treated with UV‐C or Rose‐Bengal. In contrast, wild‐type and aao1S exhibited higher aldehyde accumulation that resulted in lower remaining chlorophyll than in aao2KO leaves, indicating that the absence of active AAO2 enhanced AAO3 detoxification activity in aao2KO mutants. In support of this notion, employing abscisic‐aldehyde as a specific substrate marker for AAO3 activity revealed enhanced AAO3 activity in aao2KO and aao3Ss leaves compared to wild‐type treated with UV‐C or Rose‐Bengal. The similar abscisic‐acid level accumulated in leaves of unstressed or stressed genotypes indicates that aldehyde detoxification by AAO3 is the cause for better stress resistance in aao2KO mutants. Employing the sulfuration process (known to activate aldehyde oxidases) in wild‐type, aao2KO, and molybdenum‐cofactor sulfurase (aba3‐1) mutant plants revealed that the active AAO2 in WT employs sulfuration processes essential for AAO3 activity level, resulting in the lower AAO3 activity in WT than AAO3 activity in aao2KO. Significance Statement: The current study demonstrates that impairment of AAO2 causes enhancement of AAO3 activity and carbonyl aldehyde detoxification increase in Arabidopsis. [ABSTRACT FROM AUTHOR]

Aldehyde decarbonylation is a vital chemical transformation in the synthesis of natural products. Nature accomplishes this process through a family of decarbonylase enzymes, while in the laboratory, harsh transition metals and elevated temperatures are required. Herein, we report a mild aldehyde decarbonylation reaction that exhibits exclusive selectivity for ortho -aldehydes during a tandem nitrile boronic acid cross-coupling reaction. A wide substrate scope is displayed that includes regioselective removal of the ortho -aldehyde from phenyl boronic acids in the presence of meta - or para -aldehydes. A mechanistic investigation of the observed regioselectivity for ortho -aldehydes by density functional theory (DFT) calculations shows that the CO ligand extrusion is energetically more favorable for the ortho position as compared to the para position. [ABSTRACT FROM AUTHOR]

Dynamic chitosan-based hydrogels with enhanced antioxidant activity were synthesized through the formation of reversible imine linkages with 5-methoxy-salicylaldehyde. These hydrogels exhibited a porous structure and swelling capacity, influenced by the crosslinking degree, as confirmed by SEM and POM analysis. The dynamic nature of the imine bonds was characterized through NMR, swelling studies in various media, and aldehyde release measurements. The hydrogels demonstrated significantly improved antioxidant activity compared to unmodified chitosan, as evaluated by the DPPH method. This research highlights the potential of developing pH–responsive chitosan-based hydrogels for a wide range of biomedical applications. [ABSTRACT FROM AUTHOR]

Purple-fleshed sweetpotatoes (PFSPs) are rich in anthocyanins and are one of the health foods of interest. In this study, the effects of steaming on the anthocyanin, starch, soluble sugar, volatile organic compounds (VOCs) and pasting properties of nine PFSPs from China were investigated. The anthocyanin content of raw PFSP ranged from 9 to 185 mg/100 g. The total starch content decreased and soluble sugar content increased in all purple potatoes after steaming. Among the nine PFSPs varieties, Guangshu20 showed the greatest decrease in starch content (30.61%) and the greatest increase in soluble sugar content (31.12%). The pasting properties affected the taste of the PFSPs, with Shuangpihuang having the lowest peak viscosity (720.33 cP) and Guangzishu12 having the highest peak viscosity (2501.67 cP). Correlation studies showed that the anthocyanin content and pasting properties were negatively correlated with most of the sensory indicators, whereas the soluble sugar content of steamed PFSPs was significantly positively correlated with sweetness. A total of 54 VOCs were identified in this study, and aldehydes and terpenoids were the major VOCs in PFSPs. This study provides a theoretical basis for the processing of different PFSP varieties. [ABSTRACT FROM AUTHOR]

Two novel synthetic routes to 4‐(N‐Boc‐N‐methylaminomethyl)benzaldehyde, an important pharmaceutical starting material, were developed using terephthaloyl chloride and terephthalaldehyde. In the first approach, terephthaloyl chloride was converted to an ester amide. The treatment of the ester amide with LiAlH4 followed by protection of the resulting amine with tert‐butoxycarbonyl anhydride yielded the corresponding benzyl alcohol. The benzyl alcohol was oxidized to the aldehyde completing the first‐generation synthesis. The second approach utilized a one‐step protocol mono‐selective reductive amination of terephthalaldehyde with N‐Boc‐methylamine using chlorodimethylsilane. Both methods were scalable to 50 mmol and provided the desired aldehyde in a synthetically useful yield, demonstrating their practicality. [ABSTRACT FROM AUTHOR]

Aldehyde exposure has been shown to lead to the formation of DNA damage comprising of DNA-protein crosslinks (DPCs), base adducts and interstrand or intrastrand crosslinks. DPCs have recently drawn more attention because of recent advances in detection and quantification of these adducts. DPCs are highly deleterious to genome stability and have been shown to block replication forks, leading to wide-spread mutagenesis. Cellular mechanisms to prevent DPC-induced damage include excision repair pathways, homologous recombination, and specialized proteases involved in cleaving the covalently bound proteins from DNA. These pathways were first discovered in formaldehyde-treated cells, however, since then, various other aldehydes have been shown to induce formation of DPCs in cells. Defects in DPC repair or aldehyde clearance mechanisms lead to various diseases including Ruijs-Aalfs syndrome and AMeD syndrome in humans. Here, we discuss recent developments in understanding how aldehydes form DPCs, how they are repaired, and the consequences of defects in these repair pathways. [ABSTRACT FROM AUTHOR]

The catalytic direct hydroarylation of alkynamides is a highly efficient approach for accessing functionalized trisubstituted arylalkenes with amide groups. Herein, we report a rhodium‐catalyzed pyridylation of alkynamides with pyridylboronic acids, producing a variety of primary, secondary, and tertiary enamides with high yields (up to 94 %). This reaction demonstrates broad tolerance towards various alkyl and aryl functional groups, providing convenient access to a diverse array of alkenylpyridine derivatives. To demonstrate potential applications in late‐stage hydropyridylation, we synthesized α,β‐unsaturated ketones, aldehydes, and esters with high yields from the pyridylation product of Weinreb amides. This indirect expansion of the substrate scope enhances the practicality of this strategy. Additionally, the α,β‐unsaturated ketone obtained can be further reduced to yield a chiral alcohol with a 99 % ee, further demonstrating the versatility and potential utility of this approach. [ABSTRACT FROM AUTHOR]

A simple and mild protocol for the direct synthesis of vinyl nitriles is described. By employing potassium trimethylsilanolate as the mild base and benzyl chloride as the efficient promoter, a series of E‐configured vinyl nitriles are selectively obtained from readily available aldehydes and acetonitrile at room temperature without the aid of a transition metal catalyst. Mechanistical investigations reveal that this transformation may go through a Knoevenagel condensation process. [ABSTRACT FROM AUTHOR]

Carbonyl addition serves as a strategically straightforward and versatile approach for synthesizing alcohols, which are often encountered within bioactive molecules. Herein, we present a ligand‐free, nickel‐catalyzed carbonyl addition process using organoboron reagents. This method enables efficient arylation of readily available ketones or aldehydes, affording a variety of tertiary and secondary alcohols. Key highlights of this protocol include the obviation of external ligands and the tolerance to many functional groups and heterocycles, thereby enhancing its practicality and utility in synthetic organic chemistry. [ABSTRACT FROM AUTHOR]

Rolling plays an important role in shaping the characteristic quality of black tea. However, the dynamic alterations in volatile compounds during the rolling process remain unclear, which hampers the quality control of black tea. In this study, the dynamic changes of volatile compounds in Congou black tea throughout the rolling process were explored by a combination of GC-E-Nose and GC-MS analysis. The results of PCA and PLS-DA by GC-E-Nose revealed significant alterations in the volatile profiles, particularly at the 15-min rolling stage. A total of 82 volatile compounds including eight categories were identified in Congou black tea during the rolling process. The most abundant volatiles were aldehydes, alcohols, and esters. Through the integration of variable importance in the projection >1 and p < 0.05, 21 volatile compounds were pinpointed as pivotal volatiles responsible for distinguishing diverse rolling processes. According to their pathways, glycoside-derived volatiles (GDVs) (such as linalool and geraniol) and fatty acid-derived volatiles (FADVs) (such as (Z)-2-hexen-1-ol and hexanal) highlighted the pivotal role in the formation of the aroma of black tea during rolling process. GDVs, characterized by floral, honeyed, and fruity aromas, reached the lowest point at 35-min rolling and subsequently rebounded. FADVs exhibited an ascending trajectory during the initial 15-min rolling, followed by a downward trend. These findings provide invaluable insights into the aroma evolution during the rolling stage, offering strategies for enhancing the aroma quality of Congou black tea. [ABSTRACT FROM AUTHOR]

The catalytic pyrolysis of guaiacol-based lignin monomers, vanillin, syringol, and eugenol over commercial HZSM-5 has been investigated using operando Photoelectron Photoion Coincidence (PEPICO) spectroscopy to unveil the reaction mechanism by detecting reactive intermediates, such as quinone methides and ketenes, and products. Vanillin shares the decomposition mechanism with guaiacol due to prompt and efficient decarbonylation, which allows us to control this reaction leading to a phenol selectivity increase by switching to a faujasite catalyst and decreasing the Si/Al ratio. Syringol first demethylates to 3-methoxycatechol, which mainly dehydroxylates to o- and m-guaiacol. Ketene formation channels over HZSM-5 are less important here than for guaiacol or vanillin, but product distribution remains similar. C3 addition to guaiacol yields eugenol, which shows a more complex product distribution upon catalytic pyrolysis. By analogies to monomers with simplified functionalization, namely allylbenzene, 4-allylcatechol, and 4-methylcatechol, the eugenol chemistry could be fully resolved. Previously postulated reactive semi-quinone intermediates are detected spectroscopically, and their involvement opens alternative pathways to condensation and phenol formation. Allyl groups, produced by dehydroxylation of the β-O-4 bond, may not only decompose via C1/C2/C3 loss, but also cyclize to indene and its derivatives over HZSM-5. This comparably high reactivity leads to an unselective branching of the chemistry and to a complex product distribution, which is difficult to control. Indenes and naphthalenes are also prototypical coke precursors efficiently deactivating the catalyst. We rely on these mechanistic insights to discuss strategies to fine-tune process conditions to increase the selectivities of desired products by enhancing either vanillin and guaiacol or supressing eugenol yields from native lignin. [ABSTRACT FROM AUTHOR]

Stimuli‐responsive circularly polarized luminescence (CPL) materials based on cholesteric liquid crystal (CLC) platforms show great promise for applications in information encryption and anticounterfeiting. In this study, we constructed a mercury ion‐responsive CPL system in CLCs by controlling the conjugation degree of axially chiral binaphthyl derivatives. Two chiral binaphthyl derivatives (R/S‐1 and R/S‐2) were initially used as chiral dopants to demonstrate that CPL inversion (glum values from 0.5/‐0.44 to −0.53/0.48) in CLCs could be achieved by modulating the conjugation degree of the chiral binaphthyls. Based on this concept, the thioacetal binaphthyl R‐2S was developed and used as a mercury‐responsive chiral dopant in CLCs. Under Hg ion treatment, the CPL sign inverted (glum value changed from 0.22 to −0.29) due to the transformation of the thioacetal into an aldehyde group. Additionally, the mercury ion‐responsive CPL material was applied in information encryption. [ABSTRACT FROM AUTHOR]

Herein, we report an efficient route for coumarin C3‐C4 fused imidazole scaffolds via indium chloride‐mediated single‐step transformation of 4‐azido‐coumarin with amines/aldehydes and coumarin C3‐C4 fused 5‐substituted‐1,4‐benzodiazepine scaffolds with 1,2‐azide‐nitrogen migration through two‐step sequential synthesis via the transitory intermediacy of 2,3‐bridged‐2H‐azirine. A plausible mechanistic pathway has been proposed from the control/entrapment experiments and 1H‐NMR studies. This protocol provides the reaction condition‐dependent product selectivity, structural diversification, and excellent yields. [ABSTRACT FROM AUTHOR]

We report an efficient protocol for oxidation of primary/secondary benzyl alcohols and benzylamines to produce corresponding aldehydes or ketones. Our unified method involves the use of commercially available (diethylamino)sulfur trifluoride (DAST) as a reagent combined with DMSO as solvent and oxidant. The reaction provided corresponding carbonyl compounds in good to excellent yields with high purity and in short reaction times. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Transition‐metal‐catalyzed asymmetric alkylation of aldehydes represents a straightforward strategy for the synthesis of chiral secondary alcohols. However, efficient methods using organoborons as coupling reagents are rare. Herein, we report a highly enantioselective nickel‐catalyzed alkylation reaction of aldehydes, using readily available alkylborons as nucleophiles. A wide variety of chiral secondary alcohols were prepared from commercially available aldehydes with high yields. The key to the excellent enantioselectivity and chemoselectivity was the employment of a bulky C2‐symmetric chiral NHC ligand. This protocol features excellent enantiocontrol, mild conditions, and good functional group compatibility. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Transition‐metal‐catalyzed asymmetric alkylation of aldehydes represents a straightforward strategy for the synthesis of chiral secondary alcohols. However, efficient methods using organoborons as coupling reagents are rare. Herein, we report a highly enantioselective nickel‐catalyzed alkylation reaction of aldehydes, using readily available alkylborons as nucleophiles. A wide variety of chiral secondary alcohols were prepared from commercially available aldehydes with high yields. The key to the excellent enantioselectivity and chemoselectivity was the employment of a bulky C2‐symmetric chiral NHC ligand. This protocol features excellent enantiocontrol, mild conditions, and good functional group compatibility. [ABSTRACT FROM AUTHOR]