Aldehyde Components Research Articles

Synthesis of 4-Hydroxyquinolines as Potential Cytotoxic Agents.

The synthesis of alkyl 2-(4-hydroxyquinolin-2-yl) acetates and 1-phenyl-4-(phenylamino)pyridine-2,6(1H,3H)-dione was optimised. Starting from 4-hydroxyquinolines (4HQs), aminomethylation was carried out via the modified Mannich reaction (mMr) applying formaldehyde and piperidine, but a second paraformaldehyde molecule was incorporated into the Mannich product. The reaction also afforded the formation of bisquinoline derivatives. A new 1H-azeto [1,2-a]quinoline derivative was synthesised in two different ways; namely starting from the aminomethylated product or from the ester-hydrolysed 4HQ. When the aldehyde component was replaced with aromatic aldehydes, Knoevenagel condensation took place affording the formation of the corresponding benzylidene derivatives, with the concomitant generation of bisquinolines. The reactivity of salicylaldehyde and hydroxynaphthaldehydes was tested; under these conditions, partially saturated lactones were formed through spontaneous ring closure. The activity of the derivatives was assessed using doxorubicin-sensitive and -resistant colon adenocarcinoma cell lines and normal human fibroblasts. Some derivatives possessed selective toxicity towards resistant cancer cells compared to doxorubicin-sensitive cancer cells and normal fibroblasts. Cytotoxic activity of the benzylidene derivatives and the corresponding Hammett–Brown substituent were correlated.

Application of partially aromatic ortho-quionone-methides for the synthesis of novel naphthoxazines with improved antibacterial activity

Starting from naphthols and morpholine and using ethyl glyoxylate as the aldehyde component in the modified Mannich reaction, new aminonaphthol derivatives substituted with 2- and 1-naphthol were synthesised. The stabilization of precursor bifunctional compounds via partially aromatic ortho-quinone methide intermediate was tested with different cyclic imines in [4 + 2] cycloaddition. Based on 1H NMR analysis, in the case of new α-amino acid esters the formation of a single product has been assumed. The NOE spectrum proved that the relative configuration of the newly formed stereogenic centres was trans. The compounds have also been tested in bacteria in order to reduce or reverse antibiotic resistance. Compounds 13 and 14 could inhibit the efflux pump system in susceptible and methicillin-resistant Staphylococcus aureus strains.

Front Cover: Synthetic Study of 5‐Hydroxymethylfurfural in Groebke‐Blackburn‐Bienaymé Reaction (Eur. J. Org. Chem. 10/2022)

The Front Cover illustrates the use of renewable 5-hydroxymethylfurfural as the aldehyde component in the GBB-3CR multicomponent reaction under environmentally friendly conditions. The new imidazole heterocycles obtained under mild conditions could contribute to exploring the so-called renewable chemical space. Subsequent transformations on the hydroxymethylfuran moiety present in the GBB products will broaden the molecular diversity. Cover picture created with the help of Santiago Porcal. More information can be found in the Research Article by G. V. López, W. Porcal et al.

Synthetic Study of 5‐Hydroxymethylfurfural in Groebke‐Blackburn‐Bienaymé Reaction

AbstractIn the present study, we explored the reactivity of 5‐hydroxymethylfurfural (5‐HMF), a renewable platform chemical, as the aldehyde component in the Groebke‐Blackburn‐Bienaymé (GBB) multicomponent reaction. Given the limited stability of 5‐HMF under conventional conditions used for this reaction, acidic milieu in combination with high temperature or long reaction times, we explored factors which influence the course of the reaction (solvent, catalyst, time, and temperature) within the guidelines of previously reported green reaction conditions. Mild conditions and short reaction times were achieved to obtain good conversion and selectivity values. The reaction scope was exemplified by preparing a small compound library based on the optimized conditions varying the amidine and the isocyanide component. The hydroxymethylfuran moiety present in the GBB products, imidazo[1,2‐a]heterocycles, provides useful functionalization for further transformations, which could expand the diversity of the chemical space.

Electrosynthesis of 1,3,5-trisubstituted 1,2,4-triazoles from phenylhydrazine, aldehydes and amines under mild conditions

A simple and convenient method for the electrosynthesis of 1,3,5-trisubstituted 1,2,4-triazoles with three components of phenylhydrazine, aldehydes and amines has been established. The electrolysis could be smoothly carried out at room temperature without additional strong oxidants and catalysts to afford the target product in good yields. This electrochemical route effectively extends synthetic field of 1,2,4-triazole derivatives.

Changes of Volatile Flavor Compounds in Large Yellow Croaker (Larimichthys crocea) during Storage, as Evaluated by Headspace Gas Chromatography-Ion Mobility Spectrometry and Principal Component Analysis.

The large yellow croaker is one of the most economically important fish in Zhoushan, Zhejiang Province, and is well known for its high protein and fat contents, fresh and tender meat, and soft taste. However, the mechanisms involved in its flavor changes during storage have yet to be revealed, although lipid oxidation has been considered to be one important process in determining such changes. Thus, to explore the changes in the flavor of large yellow croaker fish meat during different storage periods, the main physical and chemical characteristics of the fish meat, including the acid value, peroxide value, p-anisidine value, conjugated diene value, and identities of the various flavor substances, were investigated and analyzed by multivariable methods, including headspace gas chromatography–ion mobility spectrometry (GC-IMS) and principal component analysis (PCA). It was found that after 60 d storage, the types and contents of the aldehyde and ketone aroma components increased significantly, while after 120 d, the contents of ketones (2-butanone), alcohols (1-propanethiol), and aldehydes (n-nonanal) decreased significantly. More specifically, aldehyde components dominated over ketones and lipids, while the n-nonanal content showed a downward trend during storage, and the 3-methylbutanol (trimer), 3-methylbutanol (dimer, D), 3-pentanone (D), and 3-pentanone (monomer) contents increased, whereas these compounds were identified as the key components affecting the fish meat flavor. Furthermore, after 120 d storage, the number of different flavor components reached its highest value, thereby confirming that the storage time influences the flavor of large yellow croaker fish. In this context, it should be noted that many of these compounds form through the Maillard reaction to accelerate the deterioration of fish meat. It was also found that after storage for 120 d, the physical indices of large yellow croaker meat showed significant changes, and its physicochemical properties varied. These results therefore demonstrate that a combination of GC-IMS and PCA can be used to identify the differences in flavor components present in fish meat during storage. Our study provides useful knowledge for understanding the different flavors associated with fish meat products during and following storage.

Study of the effect of microwave roasting method on volatile compounds and some physicochemical attributes and sensory properties of green coffee bean

Study of the effect of microwave roasting method on volatile compounds and some physicochemical attributes and sensory properties of green coffee bean

Synthesis and Mechanistic Insights of the Formation of 3-Hydroxyquinolin-2-ones including Viridicatin from 2-Chloro-N,3-diaryloxirane-2-carboxamides under Acid-Catalyzed Rearrangements.

N-Benzyl-2-chloro-N,3-diaryloxirane-2-carboxamides, easily obtained from aromatic aldehydes and anilides of dichloroacetic acid under Darzens condensation conditions, proved to be excellent starting compounds for the synthesis of 3-hydroxyindolin-2-ones, cyclohepto[b]pyrrole-2,3-diones, and 1-azaspiro[4.5]deca-3,6,9-triene-2-ones via the C(sp2)-C(sp2) bond formation in the first case and C(sp2)-C(sp3) bond formation in the second and third cases. Under optimized reaction conditions, 3-hydroxyindolin-2-ones are obtained in a one-pot process, which involves the treatment of N-benzyl-2-chloro-N,3-diaryloxirane-2-carboxamides with CF3CO2H or AcOH/H2SO4. In the case of intramolecular cyclization, the detailed reaction channels depend strongly on the substituents present in the anilide component and in the aromatic ring of the aldehyde component of N-benzyl-2-chloro-N,3-diaryloxirane-2-carboxamides, as well as the temperature and duration of the reaction. A combined experimental and DFT mechanistic study of the formation of 1-benzyl-3-hydroxy-4-arylquinolin-2(1H)-ones showed that there are three competing reaction channels: (a) ring-closure via the ipso site, (b) ring-closure via the 1,2-Cl shift, and (c) ring-closure via the ortho site. Such mechanistic insights enabled an effective one-pot gram-scale synthesis of viridicatin from benzaldehyde and 2,2-dichloro-N-(4-methoxybenzyl)-N-phenylacetamide.

A Family of Heterobimetallic Cubes Shows Spin-Crossover Behaviour Near Room Temperature.

Using 4‐(4′‐pyridyl)aniline as a simple organic building block in combination with three different aldehyde components together with metal(II) salts gave three different Fe8Pt6‐cubes and their corresponding Zn8Pt6 analogues by employing the subcomponent self‐assembly approach. Whereas the use of zinc(II) salts gave rise to diamagnetic cages, iron(II) salts yielded metallosupramolecular cages that show spin‐crossover behaviour in solution. The spin‐transition temperature T 1/2 depends on the incorporated aldehyde component, giving a construction kit for the deliberate synthesis of spin‐crossover compounds with tailored transition properties. Incorporation of 4‐thiazolecarbaldehyde or N‐methyl‐2‐imidazole‐carbaldehyde yielded cages that undergo spin‐crossover around room temperature whereas the cage obtained using 1H‐4‐imidazolecarbaldehyde shows a spin‐transition at low temperatures. Three new structures were characterized by synchrotron X‐ray diffraction and all structures were characterized by mass spectrometry, NMR and UV/Vis spectroscopy.

Synthesis of three quasi liquid Schiff bases between hexanal and adenine, cytosine, and l-leucine, structural interpretation, quantum mechanical studies and biological activity prediction

Hexanal, a naturally phytochemical known to inhibit phospholipase-D and facilitates extension of shelf-life of fruits, vegetables and flower during storage. We attemped to synthesise three quasi liquid Schiff bases using hexanal as the aldehyde component and other three natural biomolecules like adenine, cytosine and l-leucine as the amine counterpart and characterised them using different spectroscopic methods like FTIR, FT-NMR, UV–VIS etc. Detailed vibrational and electronic spectral explanation are reported using experimental spectra and theoretically simulated spectra. The compound was optimised using DFT- B3LYP/6–311 + G(2d,p) and electronic spectra was generated using CAM-B3LYP functional and same basis sets. Schiff base from cytosine was found to show excellent light harvesting properties (99.99%). Analysis of wave function based properties like electrostatic potential, ALIE, non-covalent interactions etc provide information about the reactivity and stability features. PASS and subsequent docking studies predicts that the first Schiff base shows DNA Lyase inhibition and the other two shows anti-eczematic properties.

Variations of aldehyde emission from representative tree species in urban forests by climate change

The aldehydes emitted from the main tree species composing the urban forest in South Korea were investigated. P. sargentii, Z. serrata, G. biloba, T. cuspidata, and M. glyptostroboides were considered target tree species. Variations of aldehyde emission rates were observed in relation to photosynthetic activity, temperature and photosynthetically active radiation (PAR) conditions. By comparing the apparent quantum yield (AQY) results indicating photosynthetic activity with the aldehyde ER results, it was confirmed that the photosynthetic characteristics of the trees influence the aldehyde emission. The highest standard emission rate (at a standard condition: 30 °C and 1000 μmol m−2 s−1) of total aldehyde was found in Z. serrata (i.e., 964.9 ng gdw−1 h−1). On the other hand, the tree with the lowest standard emission rate was G. biloba (i.e., 164.6 ng gdw−1 h−1). The composition ratios of emitted aldehydes differed according to the kind of tree. For most trees, formaldehyde and acetaldehyde emissions were of high proportions, and their standard emission rates showed the highest value among all aldehyde components. Two models (the T80 model considering only the temperature, and the G93 model considering the effect of both temperature and PAR) were used to calculate the standard aldehyde emission rate, and their correlation coefficient values compared by tree species. However, both models showed low correlation coefficients (below 0.77 (r2)) at all target trees.

Novel 2‐Pyrazolin‐5‐one Derivative through Unforeseen Orthoamide Intermediate: Mechanistic Insights on Isocyanide Based [4+1] Cycloaddition

AbstractThis work relates a unique one‐pot procedure to assembly novel 2‐pyrazolin‐5‐one derivative functionalized through an isocyanide based formal [4+1] cycloaddition. A new, unexpected multicomponent reaction occurred when a pyrazolone was condensed with an aldehyde, an isocyanide, and water or alcohol components. Nine novel molecules with an embedded alkyl carboxamide group were obtained in moderate yield. Surprisingly, an unforeseen orthoamide intermediate was isolated and characterized, proving the plausible mechanism for the opened imidate obtained by formal [4+1] cycloaddition. This one‐pot approach to pyrazolone derivatives functionalized with amides stands as a significant advance for preparing this class of molecules.

One-рot синтез и строение изомерных арилзамещенных триазологексагидрохиназолинов

Aryl-substituted triazolohexahydroquinazolines have been synthesized by means of three-component condensation of pnitro(pbromo) benzaldehydes, cyclohexanone, 1,2,4-triazol-3-amine. A scheme of the reaction mechanism is proposed, which makes it possible to explain the features of the behavior of p-nitro(bromo) benzaldehydes in condensation reactions in comparison with their ortho-substituted analogs. It has been found that the movement of the substituent from the ortho- tо -para-position of the benzene ring while maintaining the general direction of the reaction has a decisive effect on the number and ratio of the formed isomers and leads to the absence of hydroxylated forms of triazolohexahydroquinazolines. The composition and structure of the products have been confirmed by the data of elemental analysis, IR and one-dimensional, two-dimensional NMR spectroscopy. One-pot synthesis of aryl-substituted triazohexahydroquinazolines is a non-selective process that leads to a mixture of isomers, the structure and ratio of which is determined by the nature and position of the substituent groups in the aldehyde component.

Bioinspired AgNPs: Effective and Recyclable Catalysts towards the One‐Pot Synthesis of Hexahydroquinoline Derivatives via Three‐Component Coupling Reaction

AbstractGreen synthesis of silver nanoparticles (AgNPs) was carried out using aqueous bark extract of Shorea robusta(Sal tree) as the reducing and capping agent. AgNPs were characterized using modern characterization tools like UV‐Vis, PXRD, FT‐IR, SEM, and HR‐TEM. The catalytic application of the prepared AgNPs in three‐component coupling reaction of aldehyde, malononitrile, and cyclic enamino ketone resulted in good to excellent yields of hexahydroquinoline derivatives. Moreover, the catalyst can be recycled up to 5 times without compromising too much yield. The mechanistic pathway was investigated employing GC‐Mass spectroscopy and supported through the Density Functional Theory (DFT) calculations. A two‐step mechanism has been proposed for the coupling reaction, and the presence of electron‐withdrawing group in the aldehyde component is found to be more favorable than electron‐releasing one in terms of yield with lesser time.

Metal Cation-Driven Dynamic Covalent Formation of Imine and Hydrazone Ligands Displaying Synergistic Co-catalysis and Auxiliary Amine Effects.

Optimizing C=N bond formation and C/N component exchange has major significance in Dynamic Covalent Chemistry (DCC). Imine and hydrazone generation from their aldehyde, amine and hydrazine components showed large accelerations in presence of AgOTf or Zn(OTf)2 , up to 104 for the Zn(II)-(p-anisidine)imine complex. Zn(OTf)2 and auxiliary p-anisidine together accelerated 630 times the formation of the Zn(II)-hydrazone complex, revealing a strong synergistic effect, traced to very fast initial formation of the reactive Zn(II)-imine complex presenting a C=N bond metallo-activated towards reaction with the hydrazine component. Reactions involving more entities showed kinetically faster and thermodynamically simpler outputs due to dynamic competition within a mixture of higher complexity. Catalytic amounts of metal salts and auxiliary amine gave similar marked rate accelerations and turnover, indicating true catalysis. The synergistic effect achieved by combining metallo- and organo-catalysis points to a powerful co-catalysis strategy of bond-formation in DCC through interconnected chemical transformations.

5-Substituted N-Aminoimidazolone Peptide Mimic Synthesis by Organocatalyzed Reactions of Azopeptides and Use in the Analysis of Biologically Active Backbone and Side-Chain Topology.

Fifteen N-aminoimidazolone (Nai) dipeptides having a variety of 5-position side-chain groups were synthesized by regioselective proline-catalyzed reactions of azopeptide and aldehyde components followed by acid-mediated dehydration of an aza-aspartate semialdehyde intermediate. The introduction of 5-aryl-Nai dipeptides into cluster of differentiation 36 receptor (CD36) peptide ligands has provided insight into the conformation responsible for binding affinity and anti-inflammatory activity.

Nematocidni efekat esencijalnih ulja biljaka familije Lamiaceae NA Panagrolaimus sp. (Nematoda:Panagrolaimidae)

The long-term presence of conventional pesticides changes the ecological balance in nature, causing the disappearance of many beneficial organisms, while their residues in food and water pose a global threat to humans. The consequences of the application of large quantities of pesticides have resulted in the banning of many highly toxic compounds. In search for more environmentally friendly solutions, essential oils are being investigated. Essential oils have been used for centuries in folk medicine and today show great potential in controlling a wide range of pathogens, pests and parasites. The family Lamiaceae is one of the most important plant families in the production of essential oils. The aim of this study was to investigate the nematicidal effect of essential oils of some plants of the family Lamiaceae on free-living nematodes of the genus Panagrolaimus. A low nematicidal effect was shown by pachouli, while moderate nematicidal effects performed wild mint, wild sage, lavender, oregano, thyme and basil. The lemon balm essential oil had the strongest nematicidal impact. The aldehyde and phenolic components of terpenoids are the main constituents of the essential oils of thyme, basil and lemon balm which have shown the strongest nematicidal action and the chemicals potentially responsible for their toxicity.

Versatile and Tunable Poly(Ethylene Glycol)‐Based Hydrogels Crosslinked through the Ugi Reaction

The four-component Ugi condensation reaction has been investigated to assemble chemically crosslinked hydrogels using multivalent star-shaped poly(ethylene glycol) components. The resulting biocompatible hydrogels are highly versatile in composition and function. It is shown that acid, aldehyde, and cyanide components can be varied yielding materials with precise structure and tunable stiffness. Additionally, the resulting hydrogels were proven extremely robust to consecutive drying-swelling cycles. This property was explored to develop a reversible humidity colorimetric sensor gel. Overall, this work demonstrates the application of the four-component Ugi reaction as a powerful tool to quickly generate crosslinked gels with precise control in chemical composition.

Synthesis of bis(1,5‐disubstituted tetrazoles) via double four component Azido‐Ugi reaction

AbstractA double four component Azido‐Ugi reaction of isocyanide, TMSN3, aldehyde, and 4,4′‐sulfonyldianiline with two amine functional groups in MeOH at 65°C has been described. The synthesis of pharmacologically and structurally interesting compounds with two 1,5‐disubstituted tetrazole rings via a reaction from available and inexpensive reagents under a convenient process and mild reaction conditions has been reported. Modifications in the structure of the reaction product could be followed by varying the aldehyde or isocyanide component. The products are new and were well described by Mass, 1H NMR, and 13C NMR spectral studies.

The Cyclohexa-2,5-dienyl Group as a Placeholder for Hydrogen: Organocatalytic Michael Addition of an Acetaldehyde Surrogate.

An aldehyde with a cyclohexa‐2,5‐dienyl group in the α‐position is introduced as a storable surrogate of highly reactive acetaldehyde. The cyclohexa‐2,5‐dienyl unit is compatible with an enantioselective Michael addition to nitroalkenes promoted by a Hayashi–Jørgensen catalyst and can be removed by a boron Lewis acid mediated C−C bond cleavage. The robust two‐step sequence does not require a large excess of the aldehyde component that is typically needed when directly using acetaldehyde.