The indole core is a structural component of a huge number of biologically active natural and synthesized compounds and pharmaceuticals, and their efficient synthesis is an important challenge. Fluorinated indoles have attracted considerable attention, since it was established that fluorine introduction can influence the biological activity of organic molecules. The initial PdCl2-catalyzed intramolecular cyclization of 4,5-difluoro-2-(phenylethynyl)aniline led to the formation of the corresponding indole in high yield. The result of its subsequent treatment with Selectfluor was the introduction of one or two fluorine atoms onto position 3. The reaction products were isolated individually by preparative thin-layer chromatography and characterized by spectroscopic methods, including IR, 1H NMR, 19F NMR, 13C NMR and HRMS. The structure of indole, exhaustively fluorinated at position 3—3,3,5,6-tetrafluoro-2-phenyl-3H-indole—was confirmed through single-crystal X-ray diffraction analysis.
Macrocyclic tetraimidazolium salts 2 and 3 containing propylene and m-phenylene linkers were synthesized from diimidazole derivative 1 and 1,3-diiodopropane. The molecular structure of 3 was determined by single-crystal X-ray diffraction analysis, revealing an almost planar macrocyclic framework. DFT calculations identified three low-energy conformers of the tetracation in 3, suggesting conformational flexibility in solution.
1-[(4S)-4-benzyl-1,3-oxazolidin-2-one-3-yl]propyltriphenylphosphonium tetrafluoroborate was synthesized in a two-step procedure starting from (4S)-4-benzyl-3-propionyl-1,3-oxazolidin-2-one. In the first step, (4S)-4-benzyl-3-propionyl-1,3-oxazolidin-2-one was treated with DIBAL-H at −78 °C in DCM and then converted to (4S)-4-benzyl-3-(1-trimethylsilyloxy)propyl-1,3-oxazolidin-2-one with TMSOTf at −78 °C in DCM in the presence of pyridine. Next, the silylated intermediate was transformed to the expected 1-[(4S)-4-benzyl-1,3-oxazolidin-2-one-3-yl]propyltriphenylphosphonium tetrafluoroborate by reaction with Ph3P·HBF4 at −40 °C in DCM. The structures of the compounds obtained were confirmed by spectroscopic methods (1H-, 13C{1H}-, 31P{1H}-NMR, IR) and HRMS analysis.
This work describes the synthesis of 4-methyl-N-(2-methylbenzyl)-N′-(2-methylbenzylidene)benzenesulfonohydrazide. Full characterization of the target compound is achieved through melting point measurement, 1H NMR, 13C NMR spectroscopy and mass spectrometry, with unambiguous structural confirmation provided by single-crystal X-ray diffraction. Aggregated analytical data from multiple characterization techniques confirms successful preparation of the newly synthesized molecule and validates its structural integrity.
The design of solar cells with a bulk heterojunction is one of the most promising areas in renewable energy sources. Acceptor dopants with suitable physical characteristics are desirable components for ternary organic solar cells with cascade charge transfer. In this Short Note, 2-(4H-indeno[2,1-d][1,2,3]thiadiazol-4-ylidene)-1H-indene-1,3(2H)-dione was prepared by thionation of [1,2′-biindenylidene]-1′,3,3′(2H)-trione with Lawesson’s reagent in refluxing benzene. The structure of newly synthesized compound was strictly confirmed by spectral methods. The obtained optical and electrochemical properties make this compound a promising candidate for use in ternary organic solar cells.
Herein, we report the rapid mechanochemical synthesis of a novel hybrid amide, (±)-2-chloro-N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-2-phenylacetamide. The target compound was obtained via direct acylation of 1,4-benzodioxan-6-amine with (±)-2-chloro-2-phenylacetyl chloride under ball-milling conditions in only 1 min. Its structure was confirmed by 1H and 13C NMR, IR spectroscopy, and HRMS.
Imidazo [2,1-b][1,3]thiazines and their fused analogues are an important class of nitrogen- and sulfur-containing heterocycles that exhibit a wide range of biological activities. Herein, a straightforward synthetic protocol for 2,3-dihydro-5H-imidazo [2,1-b][1,3]thiazin-5-one under catalyst-free, mild conditions is reported. The title compound was obtained via the regioselective heterocyclization of 4,5-dihydro-1H-imidazole-2-thiol with alkyl propiolates (methyl or ethyl) by stirring at room temperature for 24 h in ethanol. The structure of the synthesized compound and the regioselectivity of the reaction were confirmed through a combination of 1H, 13C, and 2D NMR experiments (HSQC, HMBC), LC-MS, and elemental analysis. The synthesized title compound is of interest to synthetic organic and medicinal chemistry as a starting building block with potential for further core modification.
A novel spiro[indoline-3,2′-thiazolidine]-2,4′-dione derivative incorporating 3-chloro-4-fluorophenyl and 6-methoxypyridin-3-yl fragments was synthesized and characterized. The synthetic route involved a two-step procedure, including the preparation of the spirocyclic scaffold via cyclocondensation of 5-fluoroisatin with 3-chloro-4-fluoroaniline in the presence of mercaptoacetic acid, followed by Knoevenagel condensation with 6-methoxypyridine-3-carbaldehyde. The reactions were carried out under reflux conditions and afforded the desired product in a satisfactory yield after purification by recrystallization. The structure of the synthesized compound was confirmed by 1H and 13C NMR spectroscopy, LC–MS analysis, FT-IR and elemental analysis, all of which were consistent with the proposed molecular structure. The presence of multiple pharmacologically relevant heterocyclic motifs within a single framework suggests that this compound may serve as a useful scaffold for further biological evaluation.
4,8,12-Trioxaphosphangulene is a bowl-shaped phosphorus-containing π-conjugated molecule whose molecular geometry is highly sensitive to the substituent attached to the phosphorus atom. Herein, we report the synthesis of a new tungsten pentacarbonyl complex of a chiral 4,8,12-trioxaphosphangulene bearing three phenylethynyl groups. The complex was prepared by coordination of the phosphine center to an in situ generated W(CO)5 fragment and was characterized by multinuclear NMR spectroscopy and elemental analysis. The NMR spectra revealed that the phosphangulene framework retains its threefold symmetry in solution. Comparison of the NMR parameters with those of a previously reported phosphangulene–tungsten complex indicates that incorporation of the phenylethynyl substituents has little effect on either the coordination environment around the phosphorus atom or the phosphine–tungsten interaction. These findings demonstrate that the characteristic bowl-shaped phosphangulene framework is preserved upon tungsten coordination despite π-extension of the molecular framework.
Tertiary (2H-azirin-2-yl)ammonium salts were prepared from methyl 2-halo-3-aryl-2H-azirine-2-carboxylates and 1,4-diazabicyclo[2.2.2]octane in very good to excellent yields. Both iodide and bromide salts are stable enough in crystalline form to be stored in a freezer for up to several months. The structures of the obtained salts were confirmed by NMR spectroscopy and HRMS.
The target (1E,4E)-1,5-bis(2,4-dichlorophenyl)penta-1,4-dien-3-one oxime 4 was prepared in good yield, as a key aza-precursor for the Nazarov cyclization, through a two-step sequence in this study. Initially, the starting divinyl ketone 1a was obtained via a Claisen–Schmidt condensation reaction between 2,4-dichlorobenzaldehyde 3 and acetone in the presence of aqueous 20% NaOH. Subsequently, treating 1a with hydroxylamine hydrochloride under thermal conditions resulted in the expected oxime in excellent yield, and its structure was confirmed by analytic and spectroscopic techniques.
A new tert-butyldimethylsilyl-protected polyoxygenated chalcone was prepared by Claisen–Schmidt condensation of suitably protected acetophenone and benzaldehyde derivatives. Treatment of this chalcone with m-chloroperbenzoic acid (mCPBA) afforded β-(3-chlorobenzoyloxy)-α-hydroxyketone 5, which was fully characterized by spectroscopic methods. The structure of 5 is consistent with initial epoxidation of the enone double bond followed by in situ nucleophilic opening of the transient epoxide by m-chlorobenzoate generated in the reaction medium. This work reports the preparation of the chalcone precursor and the characterization of the unexpected oxidation product 5.
Rhodamine 110 (R110) peptide conjugates are widely used fluorogenic substrates in proteolytic assays; however, their inherent symmetry results in two identical hydrolysis sites, complicating their application as well-defined substrates. Here, we report a preparative enzymatic strategy for the desymmetrization of the symmetric derivative (Acetyl-Leu-Pro-Lys)2-R110 using the bovine trypsin variant D189S. Due to pronounced differences in the rates of the two sequential hydrolysis steps, a mono-substituted intermediate accumulates under controlled reaction conditions. On a preparative scale, Acetyl-Leu-Pro-Lys-R110 was generated by partial hydrolysis and isolated by preparative HPLC in 28.8% yield and 95.8% purity. The structure of the asymmetric product was fully characterized by NMR and high-resolution mass spectrometry. This work demonstrates that selective enzymatic hydrolysis provides a simple and effective preparative route to asymmetric Rhodamine 110 derivatives, offering a practical alternative to conventional multistep synthetic approaches and enabling improved substrate design for kinetic studies.
4-Methyl-N-(4-methylbenzyl)-N’-(4-methylbenzylidene)benzenesulfonohydrazide was synthesized via N-alkylation. The compound was characterized by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). Its molecular structure was unambiguously established by single-crystal X-ray diffraction analysis. The comprehensive spectral and crystallographic data conclusively verify the successful synthesis and structural integrity of this newly prepared compound.
We report the synthesis of the new compound 2-chloro-4,5,6,7-tetrafluoro-2-(methylthio)-1H-indene-1,3(2H)-dione (Compound 3), which presents an important type of fluoro-containing heterocycles and is a useful intermediate product in organic synthesis. The structure of the compound was confirmed by the NMR and elemental analysis. A quantum-chemical comparison (DFT) of 2-chloro-2-(methylthio)-1H-indene-1,3(2H)-dione (with C-H bonds, compound 4) and its 4,5,6,7-tetrafluoro derivative (with C-F bonds, compound 3) at the M06-2X/6-311++G(d,p) level in THF showed that the introduction of four fluorine atoms into the benzene ring causes a systematic shortening of the C=O, C-Cl, and C-C bonds of the five-membered ring, as well as an almost twofold decrease in the dipole moment. Replacing hydrogen with fluorine leads to a simultaneous stabilization of the frontier orbitals and a narrowing of the HOMO–LUMO energy gap, while the electron affinity increases by 0.39 eV and the electrophilicity index increases from 2.77 to 3.24 eV, making compound 3 a strong electrophile. Analysis of donor–acceptor interactions (NBOs) and condensed Fukui indices confirms that perfluorination selectively increases the electrophilicity of the sp3-carbon center of C-Cl, making it more susceptible to nucleophilic attack. At the same time, the isodesmic reaction with 1,2,4,5-tetrafluorobenzene yields a positive free energy change (ΔG = +13.4 kcal/mol), indicating that the increased reactivity of compound 3 is kinetic rather than thermodynamic in nature. The synthesized 1,3-indandione derivative thus represents a promising precursor for tetrafluoroninhydrin and can be considered a biologically active compound. Thus, perfluorination of the indandione skeleton is an effective tool for targeted enhancement of electrophilic properties without fundamentally changing the geometry of the molecule, which opens up prospects for the design of new highly reactive reagents.
Imidazolidin-2-thiones are versatile sulfur-containing heterocycles with broad biological relevance. The synthesis of (3aR,7aR)-1,3-bis(4-aminobenzyl)octahydro-2H-benzo[d]imidazole-2-thione (an imidazolidin-2-thione derivative) from trans-(R, R)-diaminocyclohexane is presented via a three-step sequence: formation of a Schiff base from 1,2-diamine and 4-nitrobenzaldehyde, followed by reduction with NaBH4; thiocarbonylation under microwave irradiation (MW) to generate the imidazolidin-2-thione core; and reduction of the nitro substituents to amines using an iron/CaCl2 system. The structure of the final compound was confirmed by detailed 1H and 13C NMR analyses, demonstrating the preservation of the bicyclic backbone and the successful conversion of the nitro functional group. The overall yield of the sequence was 28%, with the reduction of the nitro group identified as the rate-limiting step. This protocol represents a viable synthetic strategy for obtaining functionalized imidazolidin-2-thiones useful for the development of novel bioactive sulfur-containing heterocycles.
This short note presents a new molecule isolated and characterized from the reaction of uranyl nitrate with the PCP-type pincer ligand 1,3-bis(ditertbutylphosphinomethyl)benzene in the presence of UV light under ambient conditions. The new dinuclear uranyl-PCP complex was characterized by using FT-IR spectroscopy and single-crystal X-ray crystallography. As revealed by the crystal structure, the new complex had oxygen atoms coordinating from the phosphinoxides that were oxidized under ambient conditions. Each uranium atom of this dinuclear complex was found to exhibit pentagonal bipyramidal coordination geometry.
One unreported eremophilane sesquiterpenoid, 1α-methoxy-3-oxo-8α-hydroxy-10αH- eremophila-7(11)-en-12,8β-olide (1), was isolated from Ligularia fischeri. The structure of 1 was identified by detailed 1D and 2D NMR and HRMS analyses.
This study addresses the synthesis of a new liquid crystalline compound featuring a 3,5-disubstituted isoxazoline and a 1,3-dioxolan-2-one ring, and renewable aromatic building blocks derived from vanilin and benzoic acid. The target compound was synthesized through a multistep synthetic route involving alkylation, esterification, oxime formation, and a 1,3-dipolar cycloaddition reaction. The synthesized compound, 2-methoxy-4-[5-(2-oxo-1,3-dioxolan-4-yl)-4,5-dihydroisoxazol-3-yl]phenyl 4-n-decyloxybenzoate, was isolated and fully characterized by spectroscopic techniques. Liquid crystal behavior was evaluated by DSC and POM. The monotropic mesomorphic behavior of the title compound was dictated by the interplay between molecular architecture and intermolecular organization, with the methoxy substituent and the 1,3-dioxolan-2-one ring critically influencing phase stability and texture morphology. These findings suggest a structure–property relationship and guide ongoing synthetic optimization toward achieving a stable enantiotropic liquid-crystalline phase and further ion-conduction experiments.
