Synthesis Of Compounds Research Articles

A Review on the Recent Progress of Layered Double Hydroxides (LDHs)-based Catalysts for Heterocyclic Synthesis

Abstract: Over the past decade, heterocyclic compounds and their derivatives have emerged as promising substances with potential pharmacological applications due to their interesting biological properties. The significance of heterocyclic compounds in drug discovery and development is evident from the fact that a majority of drugs in the pharmaceutical market incorporate heterocyclic compounds as active substances or ingredients. Various synthetic methods and advancements have been devised to prepare these heterocyclic compounds using diverse catalysts under mild conditions. Layered double hydroxides (LDHs)-based materials have gained considerable attention across different fields, and their usability can be significantly enhanced via the selection of metal cations, their molar ratios, surface complexation, and intercalation modifications. The synthesis and application of LDH-based materials as catalysts have garnered increasing interest due to their exceptional properties. Moreover, LDH-based materials have found extensive use as heterogeneous catalysts in the synthesis of numerous heterocyclic compounds. This review presents the latest developments in the catalytic application of LDH-based materials as solid heterogeneous catalysts in the synthesis of heterocyclic compounds, covering literature published from 2018 to 2023.

Green and Convenient Synthesis of Pharmaceutically Active Mono and Bis-dihydroquinazolines via a One-pot Multicomponent Reaction Under Sulfamic Acid Catalysis

Introduction: Multicomponent reactions (MCRs) and green chemistry are essential criteria for the development of efficient chemical syntheses for valuable organic compounds. Method: The design, synthesis, and development of sustainable procedures for the production of novel biological and pharmaceutical molecules have gained high importance. Herein, an environmentally benign synthesis of mono- and bis-2,3-dihydroquinazolin-4(1H)-ones as pharmaceutically active compounds was carried out in good to high yields of 80-99% within 45-120 minutes. Result: The desired products were synthesized via three-component and pseudo five-component condensations of isatoic anhydride, a primary amine (aniline or ammonium acetate), and an aldehyde/dialdehyde using sulfamic acid (20%) as a solid acidic catalyst under the solvent-free condition at 100°C. Conclusion: The easy work-up procedure, metal-free and environmentally benign catalyst, green reaction conditions for performing MCRs, and high yields of pure products are some advantages of the presented protocol.

Fenton-ultrasound treatment of corn stalks enhances humification during composting by stimulating the inheritance and synthesis of polyphenolic compounds—preliminary evidence from a laboratory trial

The impact of Fenton-ultrasound treatment on the production of polyphenols and humic acid (HA) during corn stalk composting was investigated by analyzing the potential for microbial assimilation of polysaccharides in corn stalks to generate polyphenols using a 13C-glucose tracer. The results showed that Fenton-ultrasound treatment promoted the decomposition of lignocellulose and increased the HA content, degree of polymerization (DP), and humification index (HI). The primary factor could be attributed to Fenton-ultrasound treatment-induced enhanced the abundance of lignocellulose-degrading microorganisms, as Firmicutes, Actinobacteria phylum and Aspergillis genus, which serve as the primary driving forces behind polyphenol and HA formation. Additionally, the utilization of a 13C isotope tracer revealed that corn stalk polysaccharide decomposition products can be assimilated by microbes and subsequently secrete polyphenolic compounds. This study highlights the potential of microbial activity to generate phenolic compounds, offering a theoretical basis for increasing polyphenol production and promoting HA formation during composting.

Ultrasound-Assisted Catalyst-free Synthesis of α,β -Unsaturated Amino Acid Esters and Unsaturated Amino Ketones

Introduction: Sonication has been introduced as a green and effective activation method for the selective monoamination of β-dicarbonyl compounds. The simple one-pot process resulted in different substituted β-amino-ɑ,β-unsaturated esters and ketones at room temperature with quantitative yields. Aqueous NH4OH was used as a safe and economical nitrogen source for pressurized NH3 gas. The process is considered green, accounting for not using any solvents and catalysts, besides some aqueous NH4OH-involved reactions using nontoxic water. A broad variety of useful synthetic intermediates, β- amino-ɑ,β-unsaturated esters and ketones have been prepared in short reaction time. Methods: Using this developed protocol, we were able to synthesize a series of structurally diverse β- amino-ɑ,β-unsaturated esters and unsaturated amino ketones. Results: The synthesis of target compounds was achieved in a truly green process with high atom economy and excellent yields in a catalyst-free one-pot system in an aqueous medium using simple, commercially available, inexpensive ammonium hydroxide as the source of the nitrogen. The high atom economy has been accompanied by the formation of a small amount of nontoxic waste, water. Conclusion: In conclusion, a simple, convenient, and high-yielding catalyst-free environmentally benign method was developed for the synthesis of unsaturated amino acid esters and unsaturated amino ketones.

Synthesis of New Glucose-containing 5-Arylisoxazoles and their Enzyme Inhibitory Activity

Abstract: Carbohydrates are an important group of biomolecules that have received special attention due to their significant role in the design and synthesis of new bioactive compounds. In this study, a new class of 5-arylisoxazole-glucose hybrids was designed and synthesized for evaluation of their inhibitory effects on α-glucosidase, α-amylase, and tyrosinase. The target compounds depicted selective α-glucosidase inhibitory activity over α-amylase, which is an important factor in reducing probable gastrointestinal problems in the treatment of type 2 diabetes. In this respect, compound 9a, possessing the phenylisoxazole group, was found to be the most potent α-glucosidase inhibitor (IC50 = 292.2 ± 0.1 μM) compared to acarbose (IC50 = 750.2 ± 0.1 μM) as the positive control. All compounds were also evaluated for their anti-tyrosinase effect, and among them, compound 9j, containing a fluoroaryl moiety, showed potent activity (IC50 = 50.1 ± 6.3 μM) in comparison to kojic acid (IC50 = 23.6 ± 2.6 μM). Also, docking studies were performed to investigate the probable mode of action, which indicated the construction of important H-bonding interactions between the sugar moiety and the enzyme’s active sites. According to the results, hybrids containing heterocycles attached to glucose can be used to inhibit α-glucosidase.

Heterophase Intermetallic Compounds for Electrocatalytic Hydrogen Production at Industrial-Scale Current Densities.

Heterophase nanomaterials have sparked significant research interest in catalysis due to their distinctive properties arising from synergistic effects of different components and the formed phase boundary. However, challenges persist in the controlled synthesis of heterophase intermetallic compounds (IMCs), primarily due to the lattice mismatch of distinct crystal phases and the difficulty in achieving precise control of the phase transitions. Herein, orthorhombic/cubic Ru2Ge3/RuGe IMCs with engineered boundary architecture are synthesized and anchored on the reduced graphene oxide. The Ru2Ge3/RuGe IMCs exhibit excellent hydrogen evolution reaction (HER) performance with a high current density of 1000 mA cm-2 at a low overpotential of 135 mV. The presence of phase boundaries enhances charge transfer and improves the kinetics of water dissociation while optimizing the processes of hydrogen adsorption/desorption, thus boosting the HER performance. Moreover, an anion exchange membrane electrolyzer is constructed using Ru2Ge3/RuGe as the cathode electrocatalyst, which achieves a current density of 1000 mA cm-2 at a low voltage of 1.73 V, and the activity remains virtually undiminished over 500 h.

Static Magnetic Properties and Morphological Behaviour of Mn and Zn Substituted Ca-hexaferrite by Ceramic Technic

Synthesis of M-type hexagonal ferrite compounds, Ca(CoTi)0.5(MnZn)x/2Fe11-xO19 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2) prepared by ceramic technic. Mn and Zn ions substituted to find the magnetic characterizationat magnetic field of 10 kOe. XRD and SEM study have been done for getting the hexagonal structure of these samples. Due to the substitution of Mn and Zn ions saturation magnetization increases and magnetocrystalline anisotropy decreases. Due to the sub-latice site distribution the variations in magnetic parameters have been observed. Because of Mn and Zn ions substitution Curie temperature decreases by weakening of superexchange interaction. These materials can be used for various applications such aspermanent magnetic material, magnetic recording media, ferrofluids, sensors, microwave absorbing materials, ceramic magnets in loud speakers and rotors in small DC motors by studying various magnetic parameters from VSM characterization.

Hydrogen Sulfide Increases Drought Tolerance by Modulating Carbon and Nitrogen Metabolism in Foxtail Millet Seedlings

Hydrogen sulfide (H2S), a novel gas signaling molecule, has been shown to enhance plant resistance to various abiotic stresses. Here, we investigated the effect of sodium hydrosulfide (NaHS, a H2S donor) on the growth, photosynthetic parameters, and enzyme activities related to carbon and nitrogen metabolism, as well as the levels of carbohydrates and nitrogen metabolites in foxtail millet seedlings subjected to drought stress conditions in pots. The findings revealed that drought stress led to a significant 41.2% decline in the total dry weight (DW) after 12 days of treatment, whereas plants treated with NaHS showed a lesser reduction of 18.7% in total DW. Under drought stress, exogenous NaHS was found to enhance carbon metabolism in foxtail millet seedlings by significantly enhancing photosynthetic capacity, starch, and sucrose content. Additionally, exogenous NaHS was observed to improve nitrogen metabolism by substantially increasing soluble protein content, nitrogen assimilate activity, and synthesis of nitrogen-containing compounds in foxtail millet seedlings. In summary, the exogenous application of NaHS stimulated seedling growth and enhanced drought resistance in foxtail millet by modulating carbon and nitrogen metabolism processes affected by drought stress.

Stereodivergent Synthesis of the Four Stereoisomers of Diethyl 4-Hydroxyphosphopipecolate from Ethyl (R)-4-Cyano-3-hydroxybutanoate

The stereodivergent synthesis of all four stereoisomers of diethyl 4-hydroxyphosphopipecolate from the commercial chiral building block ethyl (R)-4-cyano-3-hydroxybutanoate is described. Key steps in the synthesis of the target compounds involve the triethyl phosphite nucleophilic addition to chiral N-acyliminium ion easily obtained from (R)-4-hydroxypiperidin-2-one, giving diethyl (2R,4R)- and (2S,4R)-4-hydroxyphosphopipecolate diastereoisomers, easily separable by column chromatography followed by the 4-hydroxy epimerization through a sequential oxidation and highly diastereoselective reduction strategy, affording the diethyl (2R,4S)- and (2S,4S)-4-hydroxy-phosphopipecolate, respectively, consistent with our recently found results. All synthesized compounds were thoroughly characterized.

Palladium complexes of N,O‐bidentate ligands bearing N‐oxide units as simple and efficient catalysts for Suzuki–Miyaura reaction of aryl halides with arylboronic acids

Palladium‐catalyzed Suzuki–Miyaura reaction is an important synthetic strategy for the synthesis of biaryl compounds. This work describes that palladium complexes with N,O‐bidentate ligands bearing N‐oxide units from cyclic secondary amines were used as highly efficient catalysts for Suzuki–Miyaura reactions of aryl halides with arylboronic acids. The reaction exhibited good functional group compatibility, high yields, and mild conditions. More importantly, these N,O‐coordinated palladium complexes could be easily prepared and displayed excellent catalytic performance for this classic Csp2–Csp2 coupling reaction in very short time.

One-pot synthesis of quinazolinone heterocyclic compounds using functionalized SBA-15 with natural material ellagic acid as a novel nanocatalyst

The nanoporous compound SBA-15 was functionalized using (3-aminopropyl)trimethoxysilane (APTES). Then the obtained product was modified with ellagic acid (ELA), a bioactive polyphenolic compound. The structure of the prepared nanoporous composition SBA-15@ELA was extensively characterized and confirmed by various techniques, such as Fourier-transform infrared (FT-IR) spectroscopy, Energy dispersive X-ray (EDX) elemental analysis, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and N2 adsorption–desorption isotherms (BET). The novel, recoverable, heterogenous SBA-15@ELA nanoporous compound was used to investigate its catalytic effect in the synthesis of 4-oxo-quinazoline derivatives (19 examples) with high yields (78–96%), as an important class of nitrogen-containing heterocyclic compounds. The use of an inexpensive mesoporous catalyst with a high surface area, along with easy recovery by simple filtration are among the advantages of this catalysis research work. The catalyst has been used in at least 6 consecutive runs without a significant loss of its activity.

A facile and efficient one-pot 3-component reaction (3-CR) method for the synthesis of thiazine-based heterocyclic compounds using zwitterion adduct intermediates

Abstract Multicomponent reactions (MCRs) are considered a green strategy by generating diversity of scaffolds from less synthetic effort and safe conditions. This work present the synthesis of dimethyl 8-(tert-butylamino)-4-oxo-4,6-dihydropyrimido[2,1-b][1,3]thiazine-6,7-dicarboxylate in low to moderate yields 33–74 % from the prepared 2-amino-4H-1,3-thiazin-4-one derivatives containing both an acidic proton and a suitable nucleophile with alkyl isocyanides and DMAD/DEtAD. The work portrays facile method under green chemical production processes using green solvents such as acetone, ethanol, isopropanol, and 2-methyl-tetrahydrofuran. This chapter shows the flexibility of zwitterion adduct from the reaction of alkyl isocyanide and DMAD. The zwitterion adduct is trapped by 2-amino-4H-1,3-thiazin-4-one derivatives and forms fused [6-6] heterocyclic compounds. The preparation of starting material thiazine was carried out at different condition from 0 °C temperatures to reflux, while the synthesis of novel dimethyl 8-(tert-butylamino)-4-oxo-4,6-dihydropyrimido[2,1-b][1,3]thiazine-6,7-dicarboxylates was done at room temperature without the use of catalyst.

The potential and pitfalls of large language models in molecular biosciences

Large language models (LLMs) have revolutionized information processing and are now being applied to complex problems in molecular biosciences. LLMs excel at learning patterns in biological sequences, enabling applications such as predicting the function of DNA regulatory elements, analysing chromatin modifications and predicting the effects of genetic variants. In drug discovery, LLMs are being used to optimize drug properties, design novel molecules and even automate compound synthesis. However, realizing the full potential of LLMs in the molecular biosciences requires addressing challenges such as designing effective learning objectives, generating high-quality, domain-specific datasets and building trust in AI-assisted decision-making. As these challenges are addressed, LLMs hold immense potential for advancing research and driving ground-breaking discoveries in molecular biosciences.

Transition‐Metal Free Arylation of Therapeutically Important Heterocycles

AbstractThe transition‐metal‐free synthesis of organic compounds especially heterocycles is in resonance with one of the twelve principles proposed by Prof. Paul Anastas in his renowned work towards the sustainable development of green chemistry. Traditional‐metal‐catalyzed reactions often involve expensive or toxic metal catalysts, and there is a growing interest in developing more sustainable and environmentally friendly methods. The arylation of heterocycles is an important area of research in organic chemistry, particularly in the synthesis of biologically active compounds and pharmaceuticals. Arylation of heterocycles at different positions enhances the potency and stability of biologically and pharmaceutically important scaffolds. In this review, an overview of the synthetic protocols developed for the arylation of a variety of heterocyclic compounds including, pyrroles, pyridines, thiophene, indole, oxindoles, purines, xanthene, etc. has been described.

Synthesis of Dienamides via Palladium-catalyzed Oxidative N-α,β-Dehydrogenation of Amides.

Enamides and their derivatives are prominent bioactive pharmacophores found in various bioactive molecules. Herein we report a palladium-catalyzed oxidative N-α,β-dehydrogenation of amides to produce a range of enamides with high yields and excellent tolerance toward different functional groups. Mechanistic studies indicate that the reaction involves allylic C(sp3)-H activation followed by β-H elimination. The effectiveness of this approach is demonstrated through late-stage functionalization of bioactive molecules and the synthesis of valuable compounds through product elaboration.

Observation of Giant Topological Hall Effect in Room-Temperature Ferromagnet Cr0.82Te

Abstract Novel magnetic materials with non-trivial magnetic structures have led to exotic magnetic transport properties and significantly promoted the development of spintronics in recent years. Among them is the CrxTey family, the magnetism of which can persist above room temperature, thus providing an ideal system for potential spintronic applications. Here we report the synthesis of a new compound, Cr0.82Te, which demonstrates a record-high topological Hall effect at room temperature in this family. Cr0.82Te displays soft ferromagnetism below the Curie temperature of 340 K. The magnetic measurement shows an obvious magneto-crystalline anisotropy with the easy axis located in the ab-plane. The anomalous Hall effect can be well explained by a dominating skew scattering mechanism. Intriguing, after removing the normal Hall effect and anomalous Hall effect, a topological Hall effect can be observed up to 300 K and reach up to 1.14 µΩ cm at 10 K, which is superior to most topological magnetic structural materials. This giant topological Hall effect likely originated from the noncoplanar spin configuration during the spin flop process. Our work extends a new CrxTey system with topological non-trivial magnetic structure and broad prospects for spintronics applications in the future.

Characterization and evaluation of actinomycete from the Protaetia brevitarsis Larva Frass

Protaetia brevitarsis larvae (PBL) are soil insects important for the soil organic carbon cycle, and PBL frass not only contains a large amount of humic acid but also affects the diversity, novelty, and potential functions of actinomycetes. Here, we characterized and assessed the actinomycete. The operational taxonomic unit (OTU) data showed that 90% of the actinomycetes cannot be annotated to species, and pure culture and genome analysis showed that 35% of the strains had the potential to be new species, indicating the novelty of PBL frass actinomycetes. Additionally, genome annotation showed that many gene clusters related to antifungal, antibacterial and insecticidal compound synthesis were identified, and confrontation culture confirmed the antifungal activities of the actinomycetes against soil-borne plant pathogenic fungi. The incubation experiment results showed that all isolates were able to thrive on media composed of straw powder and alkaline lignin. These results indicated that PBL hindgut-enriched actinomycetes could survive in soil by using the residual lignocellulose organic matter from plant residues, and the antibiotics produced not only give them a competitive advantage among soil microflora but also have a certain inhibitory effect on plant diseases and pests. This study suggests that the application of PBL frass can not only supplement soil humic acid but also potentially affect the soil microbiota of cultivated land, which is beneficial for the healthy growth of crops.

Leaf wax n-alkane distribution and hydrogen isotopic fractionation in fen plant communities of two Mediterranean wetlands (Tenaghi Philippon, Nisí fen—Greece)

Many continental paleoclimate archives originate from wetland sedimentary sequences. While several studies have investigated biomarkers derived from peat-generating vegetation typical of temperate/boreal bogs (e.g., Sphagnum), only scant information is available on emergent plants predominant in temperate/subtropical coastal marshlands, peri-lacustrine and fen environments. Here, we address this gap, focusing on two wetlands in the Mediterranean (Nisí fen and Tenaghi Philippon, Greece). We examined the concentration, homologue distribution, and hydrogen stable isotopic composition (δ2H) of leaf wax n-alkanes in 13 fen plant species, their surrounding soil, and surface water during the wet growing season (spring) and the declining water table period (summer). Our findings indicate that local graminoid species primarily contribute to the soil n-alkane signal, with a lesser influence from forbs, likely owing to differences in morphology and vegetation structure. The δ2H values of surface and soil water align with local average annual precipitation δ2H, reflecting winter-spring precipitation. Consistently, the average δ2H of local surface, soil, and lower stem water showed negligible evaporative enrichment, confirming minimal 2H-fractionation during water uptake. We find that δ2H values of source water for wax compound synthesis in local fen plants accurately mirror local annual precipitation. Furthermore, despite differences between leaves and lower stems in n-alkane production rates, their δ2H values exhibit remarkable similarity, indicating a shared metabolic substrate, likely originating in leaves. Our net 2H-fractionation values (i.e., precipitation to leaf n-alkanes) align with those in Chinese highlands and other similar environments, suggesting consistency across diverse climatic zones. Notably, our data reveal a seasonal decrease in the carbon preference index (CPI) in plant samples, indicating wax lipid synthesis changes associated with increased aridity. Additionally, we introduce a new parity isotopic difference index (PID) based on the consistent δ2H difference between odd and even n-alkane homologues. The PID demonstrates a strong anticorrelation with plant CPI, suggesting a potential avenue to trace long-term aridity shifts through δ2H analysis of odd and even n-alkane homologues in sedimentary archives. While further development of the PID is necessary for broad application, these findings highlight the intricate interplay between plant physiology, environmental parameters, and sedimentary n-alkanes in unravelling past climatic conditions.

Carboxylation of Alkenes with CO2 via Photocatalytic Cleavage of C=C Double Bonds

Carboxylation of Alkenes with CO2 via Photocatalytic Cleavage of C=C Double Bonds

Organic Dye Photocatalyzed Synthesis of Functionalized Lactones and Lactams via a Cyclization-Alkynylation Cascade.

An organic dye photocatalyzed lactonization-alkynylation of easily accessible homoallylic cesium oxalates using ethynylbenziodoxolone (EBX) reagents has been developed. The reaction gave access to valuable functionalized lactones and lactams in up to 88% yield via the formation of two new C-C bonds. The transformation was carried out on primary, secondary, and tertiary homoallylic alcohols and primary homoallylic amines and could be applied to the synthesis of spirocyclic compounds as well as fused and bridged bicyclic lactones.