Organics

In this study, we developed an efficient strategy for constructing thieno[3,2-b]thiophene molecules from 3-nitrothiophenes, containing carbonyl fragments at the C-2 and C-5 atoms, by nucleophilic aromatic substitution of the nitro group in these substrates. It was shown that the reaction of 3-nitrothiophene-2,5-dicarboxylates with thiophenols, thioglycolates and 2-mercaptoacetone in the presence of K₂CO₃ proceeds rapidly via nucleophilic displacement of the nitro group with the formation of 3-sulfenylthiophene-2,5-dicarboxylates. Further treatment of the resulting thiophene-2,5-dicarboxylates, which have -SCH₂CO₂Alk or -SCH₂COMe moiety at C-3 atom, with sodium alcoholates afford obtaining 2,3,5-trisubstituted thieno[3,2-b]thiophene derivatives according to the Dieckman condensation. In turn, the reaction of methyl 5-formyl-4-nitrothiophene-2-carboxylate with methyl thioglycolate or 2-mercaptoacetone in the presence of K₂CO₃ proceeds to directly form 2,5-disubstituted thieno[3,2-b]thiophenes. Full article

1,5-Acrylodan (1-(5-(dimethylamino)naphthalen-1-yl)prop-2-en-1-one) is prepared in six steps from 1-nitronaphthalene and 19% overall yield. The last three steps involve an aryllithium-directed nucleophilic addition, catalytic Kulinkovich cyclopropanation, and copper-catalyzed oxidative ring-opening to generate the acryloyl moiety. The fluorescent properties of 1,5-Acrylodan (AC) are reported. These include its solvatochromism and H-bond quenching by protic solvents. Its use as a bioconjugate sensor is demonstrated with Human Serum Albumin (HSA) through its covalent attachment to Human Serum Albumin (HSA) at the free cysteine-34 moiety. Unfolding studies with guanidinium chloride (GdmCl) and sodium dodecyl sulfate (SDS) are conducted to illustrate how the fluorophore responds to changes in both micropolarity and exposure to water. Full article

l-(+)-Furanomycin 1 is a miniature antibacterial natural product that contains an α-amino acid core. This non-proteinogenic α-amino acid was first isolated in 1967 by Katagiri and co-workers from the fermentation broth of Streptomyces threomyceticus L-803 (ATCC 15795). It is a substrate of isoleucyl aminoacyl-tRNA synthetase that replaces isoleucine in the protein translation process and exhibits antibacterial properties in vitro. It effectively acts as an antibacterial agent against M. tuberculosis, E. coli, B. subtilis, and some Shigella and Salmonella bacterial species at concentrations as low as the micromolar range. Consequently, synthetic chemists have garnered considerable interest from their specific structure–activity profile, distinctive chemical compositions, and distinct biological profile. This review comprehensively describes cutting-edge synthetic methodologies for synthesizing furanomycin and its analogs reported to date. Therefore, this review will offer an initial perspective on synthesizing furanomycin and its customized compounds. Full article

The triazole scaffold is a crucial component of heterocyclic chemistry, serving as a basic building block in organic synthesis, materials science, and medicinal chemistry. Triazole is a five-membered ring composed of three nitrogen atoms and two carbon atoms, and it exists in two isomeric forms: 1,2,3-triazole and 1,2,4-triazole. Compounds featuring the triazole ring are important heterocycles known for their diverse biological activities, including antimicrobial, antiproliferative, antimalarial, anticonvulsant, anti-inflammatory, antineoplastic, antiviral, analgesic, and anticancer properties. As a result, triazole derivatives have attracted significant attention from researchers. This review aims to provide a thorough overview of the published studies on the synthesis of triazole derivatives, highlighting various methods for obtaining the triazole moiety. These methods include classical approaches as well as microwave and ultrasound-assisted techniques. Full article

Pd EnCat™ 30 is a palladium catalyst broadly used in several hydrogenation and cross-coupling reactions. It is known for its numerous beneficial features, which include high-yielding performance, easy recovery, and reusability. However, the available data regarding its recyclability in Suzuki coupling reactions are limited to a few reaction cycles and, therefore, fail to explore its full potential. Our work focuses on investigating the extent of Pd EnCat™ 30 reusability in Suzuki cross-coupling reactions by measuring its performance according to isolated yields of product. Our findings demonstrate that Pd EnCat™ 30 can be reused over a minimum of 30 reaction cycles, which is advantageous in terms of cost reduction and more sustainable chemical production. Full article

Photodynamic therapy (PDT) is a clinically approved therapeutic option for the treatment of various types of cancer. PDT calls for the application of photosensitizers (PSs) and photoactivation with a particular light wavelength while tissue oxygen is present. Anticancer efficacy depends on the combination of these three substrates leading to the generation of cytotoxic reactive oxygen species (ROS) that promote apoptosis, necrosis, and autophagy of cancer cells. However, one of the biggest problems with conventional PDT is the poor accumulation and targeting of PSs to tumor tissues, resulting in undesirable side effects and unfavorable therapeutic outcomes. To overcome this, new photosensitizers have been developed through bioconjugation and encapsulation with targeting molecules, such as peptides, allowing a better accumulation and targeting in tumor cells. Several studies have been conducted to test the efficacy of several peptide-conjugated photosensitizers and improve PDT efficacy. This review aims to present current insights into various types of peptide-conjugated photosensitizers, with the goal of enhancing cancer treatment efficacy, addressing the limitations of conventional PDT, and expanding potential applications in medicine. Full article

From Egyptian mummies to the Chanel N° 5 perfume, aldehydes have been used for a long time and continue to impact our senses in a wide range of perfumes, foods, and beverages. Aldehydes represent one of the categories of volatile organic compounds (VOCs), which are categorized as chemicals with boiling points up to 260 °C and can be found in indoor environments in the gaseous phase. Because of their potential or known hazardous properties for humans, the World Health Organization (WHO)-Europe provided some guidelines that may prevent several health risks. Indeed, some aldehydes, reported to be risky for humans, have been retired from the market, such as butylphenyl methylpropional (BMHCA). The purpose of this review is to summarize the most important aldehydes found indoors and outdoors and analyse in depth the toxicological aspects of these compounds, whose presence in perfumes is often underestimated. In addition, the ingredients’ synonyms that are reported in the literature for the same compound were unified in order to simplify their identification. Full article

In this contribution, propylamine-functionalized cellulose (Cell-Pr-NH₂) was employed as the catalyst in the three-component reaction between hydroxylamine hydrochloride and various types of aryl/heteroaryl aldehydes, ethyl acetoacetate/ethyl 4-chloroacetoacetate, or ethyl 3-oxohexanoate. The result of these experiments was the formation of 3,4-disubstituted isoxazol-5(4H)-one heterocycles. The desired five-membered heterocyclic compounds were obtained in good to high yields at room temperature. The investigation of different solvents led us to the conclusion that water is the best solvent to perform the current one-pot, three-component reactions. Attempts to find the optimal catalyst loading clearly showed that 14 mg of cell-Pr-NH₂ seems to be sufficient to carry out the reactions. This method has highlighted some principles of green chemistry including less waste generation, atom economy, use of water as an environmentally friendly solvent, and energy saving. Purification without chromatographic methods, mild reaction conditions, simple work-up, low-cost reaction medium, saving time, and obtainable precursors are other notable features of this one-pot fashion. Full article

Natural products have been a reliable source of drug compounds in medical research. Technological advances have led to the discovery and characterization of many compounds that were previously difficult to isolate. However, when searching for anticancer drugs, finding natural compounds that can bind to specific targets is a daunting task. Polycyclic tetramate macrolactams (PoTeMs), specifically, have been a source of antibiotics for a long time, though they possess certain cytotoxic properties that make them attractive candidates for anticancer drug discovery. This review covers the structural diversity and widespread availability of PoTeM compounds and the past research that demonstrates their effects on human cancer cell lines. Additionally, this review documents the known receptors and molecular mechanisms of these compounds in mammalian cells. Full article

Triazole derivatives of fluorescein-containing N,N-dimethylaminopropyl fragments and their ammonium salts were synthesized with yields of 74–85%. The resulting compounds exhibit fluorescent properties in the green region of the visible spectrum. The critical aggregation concentration (CAC) was estimated using a pyrene fluorescent probe corresponding to a range of 0.28–1.43 mM, and at concentrations above the CAC, the compounds form stable aggregates ranging from 165 to 202 nm. A relative quantum yield of 5–24% has been calculated based on fluorescence and UV spectra. The best value is shown by a derivative containing a tetradecyl substituent. When studying the photocatalytic properties of synthesized compounds through the reaction between N-substituted 1,2,3,4-tetrahydroisoquinoline and malonic ester, the mono-tetradecyl derivative demonstrated the best results. According to gas chromatography–mass spectrometry (GC-MS) data, the conversion of the initial heterocycle reached 95%. Therefore, these resulting compounds have the potential to act as an effective photocatalysts. Full article

Barbituric acid is a heterocyclic compound with various pharmacological and biological applications. This review paper provides a comprehensive overview of barbituric acid’s synthesis, reactions, and bio-applications, highlighting its multifaceted role in various fields. Many heterocyclic derivatives were formed based on barbituric acid, for instance, pyrano-fused pyrimidine derivatives, spiro-oxindole derivatives, chrome-based barbituric acid derivatives, and many more via the atom economic method, Michael addition reaction, Knoevenagel condensation reaction, etc. In the context of bio-applications, this review examines the production of a wide range of bioactive drugs like anti-histamine, anti-leprotic, sedative–hypnotic, anti-inflammatory, anti-urease, antiviral, anti-AIDS, antimicrobial, antioxidant, anticonvulsant, anesthetic agent, antitumor, and anticancer drugs using efficient multicomponent reactions. By showcasing the versatility and potential of this compound, it aims to inspire further research and innovation in the field, leading to the development of novel barbituric acid derivatives with enhanced properties and diverse applications, with coverage of the literature relevant up to 2024. Full article

The elaboration of a new family of tetrapodal molecules L1–L3 bearing two pyrazole–tetrazole units is presented. The structure assigned to such molecules was verified by various techniques, including FTIR, NMR, HRMS and elemental analysis. The ability of these tetrapods to inhibit the growth of four fungal strains was examined, and the obtained results showed that they have some antifungal potency in the range of 12–16 mm. The alpha-amylase inhibition activity of these molecules was also evaluated. The obtained IC₅₀ values (1.34 × 10⁻¹–1.2 × 10⁻² mg/mL) demonstrated that all compounds are potent enough to inhibit this enzyme much better than the positive control acarbose (2.6 × 10⁻¹ mg/mL). A docking study on the porcine alpha-amylase was performed, and the results were in good correlation with the experimental results. Full article

The art of dyeing textiles has a long history, as natural dyes have been used since prehistoric times. With the development of synthetic dyes in the 19th century, the focus shifted from natural to synthetic dyes due to their superior properties. Recently, however, interest in natural dyes has increased again due to environmental and health concerns. Among industrial dyes, heterocyclic dyes, especially azo dyes, are of great importance due to their color brilliance and fastness. This review examines the synthesis, application, and analysis of azo dyes, especially heterocyclic dyes. It deals with monoazo, diazo, and polyazo dyes and highlights their structures, synthesis methods, and fastness properties. In addition, the ecological impact of azo dyes and practical solutions for their synthesis and application are discussed. Full article

A series of new aromatic substituted indanone and indanol building blocks have been prepared and are anticipated to aid future drug discovery studies. In total, seven compounds (7, 12–17) are expounded on, and all have been fully characterized. In doing so, we have shown multiple examples of highly chemoselective reactions. One example employed an adaptation of Fujioka’s chemoselective reduction methodology, allowing an ester to be reduced in the presence of a ketone. In another example, an uncommon benzylic methyl group to aldehyde oxidation was demonstrated for two different compounds. These and other chemoselective interconversions allowed us to identify compound (12) as a remarkably flexible springboard for accessing a diverse array of indan-based building blocks (13–17). Full article

Synthesis of 3,8-diaryl-2H-cyclohepta[b]furan-2-ones was accomplished by the one-pot procedure involving sequential iodation and Suzuki–Miyaura coupling reactions. The optical and structural characteristics of 3,8-diaryl-2H-cyclohepta[b]furan-2-ones prepared were scrutinized using UV/Vis spectroscopy, theoretical calculations, and single-crystal X-ray crystallography. The redox properties of the compounds were also evaluated through cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The findings reveal that the introduction of aryl groups at both the 3- and 8-positions significantly influences the electronic properties of the CHFs, resulting in distinct optical and electrochemical characteristics. Full article

Permethylated anigopreissin A (PAA), a fully protected form of the natural anigopreissin A, was found in our previous study to be active against several cancer cells, up to IC50 0.24 μM for HepG2 cells. Herein, a total of thirteen PAA analogues with variations in the number, position of substituents and unsaturation were synthesised starting from a common precursor, and their ability to induce cell growth inhibition was tested. By comparing the antiproliferative effect of the analogues with PAA and with the help of computational studies, we have gained valuable insights into both the biological activity and structure of this natural class of compounds. Indeed, we discovered the importance of the C-3 ring in modulating the biological activity of PAA, as well as the crucial role of the trans configuration of the styryl double bond and the significance of substitutions on the other parts of the molecule. Full article

In light of the small ring strain of five/six-membered cyclic ethers, constructing complex molecules via ring-opening reactions has consistently been a highly challenging topic in organic synthesis. Induced by Lewis acids, the charge redistribution in cyclic ethers forms oxonium ylide intermediates, thereby activating the C–O bond and subsequently facilitating nucleophilic attack for ring opening. In recent years, a variety of novel Lewis acids, encompassing those with new metal centers and frustrated Lewis pairs (FLPs), have been effectively utilized to induce the formation of oxonium ylides, offering a diverse array of methods for the ring opening of five/six-membered cyclic ethers. This review conveys the extensive application advancements of diverse Lewis acid types for cyclic ether ring-opening reactions over the past two decades, originating from the perspective of the classification of Lewis acids. Furthermore, the substrate applicability and chemical transformation efficiency of these Lewis acids in the ring-opening reactions of cyclic ethers have also been discussed herein. Full article

Bridgehead alkenes are polycyclic molecules bearing at least one C=C bond that includes a bridgehead carbon atom. For small bicyclic systems, these bonds are highly strained due to geometric constraints placed on the sp² hybridized carbon atoms. These small, strained molecules have been termed “anti-Bredt” alkenes. β-halo carbanions have served as convenient precursors to bridgehead alkenes in experimental studies. We observed that upon attempted computational geometric optimizations (ωB97X-D/aug-cc-pVDZ) of the precursors, spontaneous elimination of the halide occurs along with formation of the anti-Bredt alkene in many cases. Such computational eliminations were shown to faithfully mimic experimentally obtained results. Computational elimination was not observed for [1.1.1] or [2.1.1] frameworks, in agreement with predictions that these bridgehead alkenes are too strained to be formed. However, computational elimination from the [2.2.1] framework was observed to form 1-norbornene, a compound suggested in experimental work to be a reactive intermediate. Similarly, [3.1.1] frameworks and higher led to eliminations upon computational geometric optimization, in agreement with experimental findings. Natural bond order (NBO) calculations of the starting geometries proved to be excellent predictors as to whether elimination would take place. Those precursor compounds exhibiting delocalization energies in the order of 10 kcal/mol between the lone-pair electrons of the carbon atom and σ*_C-Br were generally found to undergo elimination. Thus, computational optimization of β-halo substituted bicyclic precursor anions can be used to predict whether strained anti-Bredt alkenes are likely to be formed, thereby saving valuable time and costs in the experimental lab. Full article

This review deals with the functionalization of double bonds carried out in the presence of a chiral catalyst exploiting the intramolecular attack to haliranium ions by nucleophilic nitrogen of amides or carbamates prepared from achiral aminoalkenes, and the C–N bonds formation leads to highly enantioenriched nonaromatic heterocycles. A range of protocols are reported, emphasizing the synthesis of many natural and biologically active products of pharmacological interest prepared according to this methodology. Full article