Search Results (246)

Haloketoesters are synthetic intermediates in various cyclization reactions that facilitate the production of biologically active compounds. Nonetheless, the selective synthesis of dihaloketoesters and trihaloketoesters, which are expected to be highly versatile, presents significant challenges. In this study, we designed a new synthetic approach that selectively and efficiently produces haloketoesters through the halogenative C–C bond cleavage and ring-opening reactions of cyclic 1,3-diketones. This convenient method enables the direct synthesis of di- and trichloro-functionalized ketoesters from 1,3-cyclohexadiones under mild conditions. Na₂HPO₄, employed as a buffer salt, proved to be effective in facilitating the alcoholytic ring-opening reaction of 2,2-dichloro-1,3-cyclohexadiones, which were generated as synthetic intermediates. Full article

Background/Objectives: Breast cancer remains one of the most prevalent and life-threatening malignancies worldwide. This study describes the design and biological evaluation of a series of secosteroid–2-pyrazoline hybrids as novel antitumor agents against ERα-positive breast cancer cell lines MCF-7 and T47D. Methods: A simple and efficient method for synthesizing secosteroid–2-pyrazoline hybrids was developed starting from 13α-hydroxy-3-methoxy-13,17-secoestra-1,3,5(10)-triene-17-oic acid hydrazide and 1,3-diketones. The resulting secosteroid derivatives were evaluated against hormone-dependent MCF-7 and T47D breast cancer cells. Furthermore, the selectivity and effects of three lead compounds on signaling pathways in MCF-7 cells were examined. Flow cytometry was used to assess the cell-cycle distribution of MCF-7 cells treated with the lead compound. Results: Among the synthesized hybrids, compounds 3f, 3j, and 3k exhibited potent antiproliferative activity with IC₅₀ values of 0.2–0.5 μM against breast cancer cells, while demonstrating very low cytotoxicity towards normal cells (IC₅₀ > 25 μM), indicating a favorable safety profile. The antitumor activity of lead compound 3j was additionally investigated in combination with standard chemotherapeutics, docetaxel and doxorubicin, yielding synergistic effects. The lead compounds showed a dual mechanism of action by inhibiting S6 kinase and promoting Bcl-2 phosphorylation at 0.9 μM, without significantly affecting hormonal breast cancer targets such as ERα, GREB1, and AR. Compound 3j induced apoptosis accompanied by a reduction of the G1/G0 phase in MCF-7 cells. Conclusions: These findings highlight secosteroid–2-pyrazoline hybrids as promising candidates for the development of next-generation breast cancer therapeutics targeting apoptosis and S6K signaling pathways. Full article

Herein, we report an efficient one-pot synthesis of bridged aminodiperoxides via a three-component reaction of 1,5-diketones with geminal bishydroperoxides and ammonium acetate. The synthesized aminodiperoxides are stable despite containing an unprotected secondary NH-group adjacent to two peroxide functionalities. Under optimal conditions, the reaction affords aminodiperoxides in high yields (up to 88%) with outstanding selectivity and high atom economy, thereby eliminating the need for column chromatographic purification. The synthesized aminodiperoxides exhibit potent cytotoxicity and remarkable selectivity toward Jurkat, K562, and A549 cancer cell lines, and are significantly superior to the clinically used anticancer agent camptothecin. Among all tested compounds, 3ec is the most promising candidate, exhibiting high activity and selectivity toward all tested cell lines (Jurkat: CC₅₀ = 12.9 µM, SI = 67.09; K562: CC₅₀ = 19.6 µM, SI = 44.28; A549: CC₅₀ = 48.2 µM, SI = 17.98). Furthermore, a novel class of fungicidal compounds has been discovered. The aminodiperoxides exhibit fungicidal activity against phytopathogenic fungi, in some cases comparable to the commercial fungicide Triadimefon. Full article

A new bis(cyclopentadienyl) terbium(III) complex with 1,2,4-triphenylcyclopentadienyl and 4,4,4-trifluoro-1-phenylbutane-1,3-dionate ligands was synthesized. Single-crystal X-ray analysis revealed a mononuclear bis(cyclopentadienyl) complex with a diketonate ligand in the bisector plane. The compound under study exhibits a ligand ligand charge transfer state (LLCT), according to optical spectroscopy and crystallographic data. Full article

We report the synthesis, spectroscopic, structural, and ultrafast photophysical investigation of a series of homoleptic and heteroleptic Zn(II) complexes based on the donor-acceptor β-diketonate ligand 4,4,4-trifluoro-1-phenylbutane-1,3-dione. Mass spectrometry, infrared, and NMR analyses confirm complexation and indicate possible fragmentation pathways involving the sequential loss of β-diketonate ligands. Single-crystal X-ray diffraction revealed that all complexes adopt monomeric octahedral geometries, with the ancillary nitrogen-based ligands introducing variable distortions. Thermal analyses confirmed that the complexes are non-volatile and have an onset >250 °C, with thermal decomposition primarily to ZnO and ZnF₂. Complexes with aromatic Lewis base led to higher residue percentages, likely due to the final graphitic carbon content. UV-Vis absorption and femtosecond transient absorption spectroscopy demonstrate that the chelated β-diketonate ring serves as the main optically active chromophore, a property unaffected by the nitrogen ligands. The free ligand undergoes rapid internal conversion, whereas coordination to Zn stabilizes the triplet state via LMCT, producing long-lived and chemically reactive species relevant to dissociation processes. This study demonstrates how tailored ligand environments can be exploited to tune excited-state properties, offering a rational framework for the design of functional precursors suitable for nonlinear photolysis and advanced nanomaterial synthesis. Full article

A tandem synthetic sequence involving photo-induced intramolecular [2+2] cycloaddition followed by acid-promoted ring expansion was developed to access the novel bicyclic triketone framework. The process begins with the UV (254 nm) irradiation of cyclic vinylogous ester, affording a highly strained cyclobutane-fused diketone in an 86% yield. This unique intermediate feature is of a fused four- and six-membered ring system with spatially compressed carbonyl groups. Upon acidic hydrolysis in aqueous MeCN, the strained system undergoes retro-aldol ring expansion, delivering [5.3.0] bicyclic triketones bearing a seven- and five-membered fused ring with three strategically oriented carbonyl units in a 75% yield. Structural elucidation was performed using NMR spectroscopy, UV-Vis, HRMS, and single-crystal X-ray crystallography. The method highlights a concise route for constructing a fused bicyclic triketone of relevance to synthetic and medicinal chemistry. Full article

In continuation of our efforts to identify novel herbicide lead compounds, twenty new 5-(1-amino-4-phenoxybutylidene)barbituric acid derivatives containing an enamino diketone motif were synthesized and evaluated for their herbicidal activities. The greenhouse bioassay results indicated that several of the target compounds, including BA-1, BA-2, BA-5, BA-18, and BA-20, exhibited notable post-emergence herbicidal activity, with sum inhibition rates exceeding 70% at a dosage of 150 g ha⁻¹, which was superior to that of the commercial herbicide flumiclorac-pentyl (FP). The structure–activity relationship analysis demonstrated that the steric and electronic effects of the R group, as well as the lipophilicity of the target compounds, significantly influenced herbicidal activity. Among these, BA-1 was identified as a promising herbicide lead compound due to its high total herbicidal efficacy, broad-spectrum activity, and favorable crop safety profile. Molecular simulation studies indicated that BA-1 binds effectively to Nicotiana tabacum protoporphyrinogen IX oxidase (NtPPO), suggesting its potential as a novel PPO inhibitor. This study highlights BA-1 as a promising lead compound for the development of novel PPO-inhibiting herbicides. Full article

The highly fluorescent fluorene group is of interest for its unique optical and electronic properties. By incorporating it into a metal complex, these properties are extended to the complex and are useful in a number of different applications. Four β-diketone ligands were synthesized containing the fluorene-functional group, where the varying substituent on the β-diketone was CF₃ (1), PhCF₃ (2), Ph (3) and PhCH₃ (4). The corresponding cyclooctadiene rhodium(I) complexes of the type [Rh(cod)((fluorene)COCHCOR)], with R = CF₃ (5), PhCF₃ (6), Ph (7) and PhCH₃ (8) were also synthesized. A crystal structure determination of 2 and 6 was performed, highlighting important changes in the ligand structure as a result of metal complexation. The structure of 2 also showed a hydrogen interaction between the hydroxy and carboxyl groups, forming a pseudo six-membered ring that stabilizes the enol form of the compound. Cyclic voltammetry (CV) of the β-diketones 1–4 showed a reduction wave for the reduction of the β-diketonato backbone between −1500 mV and −2100 mV as measured against ferrocene (FcH). CVs of rhodium(I) complexes 5–8 showed a reduction of the β-diketonato backbone between −1800 and −2000 mV, as well as an oxidation wave for the oxidation of the rhodium(I) metal centre at approximately 300 mV. Full article

Achieving high quantum yields for Yb³⁺ ion emission in complexes with organic ligands is a challenging task, as most Yb³⁺ complexes with such ligands typically exhibit efficiencies below 3.5%. Our research demonstrates that the introduction of heavy atom-containing ancillary ligands, such as TPPO or TPAO, along with the careful engineering of the main β-diketone ligand, can increase the luminescence efficiency up to 20-fold by the alteration of the energy migration pathway. It is demonstrated that the combination of two distinct organic ligands leads to the blockage of singlet–triplet intersystem crossing (ISC), alongside electronic energy transfer from β-diketone to Yb³⁺ ions through charge transfer states. The synthesized complexes exhibit quantum yields of 6.5% and 7.0% in the solid state, which places them at the top globally among this class of materials with simple non-deuterated and non-fluorinated ligands. Full article

The procedure for the generation of azirinyl-substituted nitrile oxides by the reaction of 2-(diazoacetyl)-2H-azirines with tert-butyl nitrite while preserving the azirine ring has been developed. The [3+2] cycloaddition of azirinyl-substituted nitrile oxides to terminal acetylenes produced azirinyl(isoxazolyl)ketones with various substituents in position 3 of azirine and position 5 of isoxazole fragments in a 51–91% yield at room temperature in DCM. DFT calculations and experimental data are consistent with the assumption that the formation of azirinyl-substituted nitrile oxides is accelerated by the acid catalyst. Cycloadducts of nitrile oxides with aryl/hetarylacetylenes and DMAD can be obtained by catalysis with boron trifluoride etherate, which significantly expands the scope of application of the reaction. Expansion of the azirine ring of the prepared cycloadducts allows obtaining a wide range of structurally diverse functionalized isoxazole-containing heterocyclic hybrids. LED light induces isomerization of the azirinecarbonyl moiety of the azirinyl(isoxazolyl)ketones, resulting in the formation of a set of 3,5’-biisoxazoles in a 40–71% yield, while the catalytic reaction of the azirine moiety with 1,3-diketones opens the way to pyrrole- and isoxazole-containing hybrids. 2-(Isoxazole-3-ylcarbonyl)-3-arylazirines were also easily isomerized to 3-(oxazol-5-yl)isoxazoles in methanol in the presence of excess potassium carbonate at room temperature. Full article

The lubrication performance of the cylinder liner–piston ring (CLPR) is crucial for the energy efficiency and operating reliability of marine diesel engines. To enhance the boundary lubrication of marine engine oil, a 1,3-diketone fluid HPTD (1-(4-hexylphenyl) tridecane-1,3-dione, HPTD) was introduced as an ash-free friction modifier. Besides that, octadecylamine-functionalized nanocopper particles (ODA-Cu) were also added to the marine oil to improve its anti-wear behavior. Through cylinder-on-disk friction tests, the appropriate contents of HPTD and ODA-Cu were determined, which then formed hybrid additives and modified the engine oil. The tribological performance of the modified oil was analyzed under various normal loads, reciprocating frequencies, and testing temperatures. Based on the synergy of the tribochemical reaction of HPTD and the mending effect of ODA-Cu on the sliding surface, the modified oil not only had lower sulfated ash content but also exhibited superior lubrication performance (i.e., reduced coefficient of friction by 15%, smaller wear track by 43%, and higher maximum non-seizure load by 11%) than the pristine engine oil. The results of this study would be helpful for the design of novel hybrid eco-friendly additives for marine engine oil. Full article

In this work, 1,3-diketone synthesized via the Claisen condensation method and nano-copper particles modified by the Brust–Schiffrin method were added into a commercial marine medium-speed diesel engine cylinder piston oil to evaluate their effects on boundary lubrication performance. Friction and wear tests conducted on CKS-coated piston ring and cast-iron cylinder liner samples demonstrated significant reductions in both friction and wear with the addition of 1,3-diketone and nano-copper particles. Compared to the original oil without additives, the friction force was reduced by up to 16.7%, while the wear of the piston ring and cylinder liner was decreased by up to 21.6% and 15.1% at 150 °C, respectively. A worn surface analysis indicated that the addition of 1,3-diketone and functionalized nano-copper particles influenced the depolymerization and tribo-chemical reactions of the anti-wear additive ZDDP (zinc dialkyldithiophosphate) in the original engine oil. This modification enhanced the oil’s anti-friction and anti-wear properties, offering valuable insights into the development of eco-friendly lubricants for energy-efficient systems. Full article

The heteroleptic halogen-substituted Fe³⁺ complex of formula [FeL₂Bipy]Cl, where L is 1-(4-fluoro-phenyl)-3-(4-bromo-phenyl)-propane-1,3-dione and Bipy is 2,2′-bipyridine, was synthesized, and its optic and magnetic properties were studied. Magnetic measurements showed that the complex at high temperatures (T > 75 K) is predominantly in the high-spin (HS) state of Fe³⁺ ions (S = 5/2, γ_HS¹ = 93%) with a small admixture of low-spin (LS) state (S = 1/2, γ_LS¹ = 7%). At T* ≈ 46 K, a partial spin-crossover transition (SCO, 5/2↔1/2) occurs. This process is accompanied not only by a change in the magnetic state (γ_HS² = 76%, γ_LS² = 24%), but also by the appearance of AFM interactions (θ_II = −2.3 K) between neighboring Fe³⁺ ions. A theoretical model was proposed to describe magnetic susceptibility, χ(T). As a result of the analysis of the ground spin state M(H) at 2.0 K, it was established that the majority of the LS states, as well as part of the HS states of Fe³⁺ ions (γ_HS ~ 53%), do not participate in exchange interactions. EPR studies confirmed the presence of HS and LS Fe³⁺ centers and made it possible to isolate I-type and II-type HS centers, corresponding to strong low-symmetry and weak distorted octahedral fields. SCO was also detected and the temperature dependences of the EPR intensities, I(T), of the HS and LS centers were analyzed. Full article

Europium(III) β-diketone and organic carboxylic acid complexes are designable, easy to prepare, and easy to modify and have excellent fluorescence properties (narrow emission spectral band, high colour purity, long fluorescence lifetime, high quantum yield, and a spectral emission range covering both the visible and near-infrared regions). These complexes play important roles in popular fields such as laser and fibre-optic communications, medical diagnostics, immunoassays, fluorescent lasers, sensors, anticounterfeiting, and organic light-emitting diodes (OLEDs). In the field of light-emitting materials, europium complexes are especially widely used in OLED lamps, especially because of their high-efficiency emission of red (among the three primary colours); accordingly, these complexes can be mixed with blue and green phosphors to obtain high-efficiency white phosphors that can be excited by near-ultraviolet light. This paper reviews the red-light-emitting europium complexes with β-diketone and organic carboxylic acid as ligands that have been studied over the last five years, describes the current problems, and discusses their future application prospects. Full article