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Molbank

Molbank is an international, peer-reviewed, open access journal comprised of a unique collection of one-compound-per-paper short notes on synthetic compounds and natural products published bimonthly online by MDPI.

Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
High Visibility: indexed within Scopus, ESCI (Web of Science), Reaxys, CAPlus / SciFinder, and other databases.
Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 14.7 days after submission; acceptance to publication is undertaken in 3.7 days (median values for papers published in this journal in the first half of 2026).
Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Journal Cluster of Chemical Reactions and Catalysis: Catalysts, Chemistry, Electrochem, Inorganics, Molecules, Organics, Oxygen, Photochem, Reactions, Sustainable Chemistry and Molbank.

Impact Factor: 0.3 (2025)

Imprint Information Journal Flyer Open Access ISSN: 1422-8599

Latest Articles

8 pages, 5897 KB

Open AccessCommunication

Novel Fluorinated Derivatives of 2-Phenyl-1H-Indole

by Larisa Politanskaya and Irina Bagryanskaya

Molbank 2026, 2026(5), M2228; https://doi.org/10.3390/M2228 (registering DOI) - 4 Sep 2026

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 [...] Read more.

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. Full article

(This article belongs to the Collection Heterocycle Reactions)

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7 pages, 2604 KB

Open AccessCommunication

Synthesis and Structure of Macrocyclic Tetraimidazolium Salt Containing Propylene and m-Phenylene Linkers

by Jun-Ichi Ito and Makoto Yamashita

Molbank 2026, 2026(5), M2227; https://doi.org/10.3390/M2227 - 2 Sep 2026

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 [...] Read more.

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. Full article

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Graphical abstract

6 pages, 474 KB

Open AccessShort Note

N-[3-(N-tert-Butoxycarbonylaminooxy)propyl]-2-[2-(3-butynylcarbonylamino)ethylthio]-1,3-benzothiazole-6-carboxamide

by Gabriella G. Meisner, Nora N. Veigas and Christopher R. Shugrue

Molbank 2026, 2026(5), M2226; https://doi.org/10.3390/M2226 - 1 Sep 2026

We report the synthesis of a modified benzothiazole sulfide. This compound contains a heterocyclic core, a Boc-protected hydroxylamine, and an appended alkyne. This benzothiazole was accessed through three total steps, including an amidation reaction and two nucleophilic aromatic substitutions. The identity of the [...] Read more.

We report the synthesis of a modified benzothiazole sulfide. This compound contains a heterocyclic core, a Boc-protected hydroxylamine, and an appended alkyne. This benzothiazole was accessed through three total steps, including an amidation reaction and two nucleophilic aromatic substitutions. The identity of the title compound was confirmed through ¹H, ¹³C, ¹H–¹H COSY, HSQC, and HMBC NMR, in addition to IR, MALDI-MS, HRMS, and HPLC. Full article

(This article belongs to the Collection Heterocycle Reactions)

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Graphical abstract

8 pages, 1940 KB

Open AccessCommunication

Synthesis and Structural Characterization of a New One-Dimensional Zinc(II) Coordination Polymer Based on a Fluorinated Thiosemicarbazone Schiff Base Ligand

by Jinhua Wang, Guan Wang and Chengwen Li

Molbank 2026, 2026(5), M2224; https://doi.org/10.3390/M2224 - 1 Sep 2026

This study reports the synthesis and characterization of a dinuclear zinc(II) complex, [Zn₂(L1)₂(L2)]·DMF·Et₃N (C₄₅H₅₄F₂N₁₀O₅S₂Zn₂), constructed from a fluoro-substituted thiosemicarbazone [...] Read more.

This study reports the synthesis and characterization of a dinuclear zinc(II) complex, [Zn₂(L1)₂(L2)]·DMF·Et₃N (C₄₅H₅₄F₂N₁₀O₅S₂Zn₂), constructed from a fluoro-substituted thiosemicarbazone Schiff base ligand (2-(3-fluoro-5-hydroxybenzylidene)-N-methylhydrazine-1-carbothioamide, L1) and a rigid bipyridine auxiliary ligand (1,4-di(pyridin-4-yl)-2,5-dimethoxybenzene, L2) under solvothermal conditions. Single-crystal X-ray diffraction analysis reveals that the complex crystallizes in the monoclinic space group C2/c, featuring discrete dinuclear [Zn₂] units in which each Zn(II) center adopts a distorted square pyramidal geometry. These dinuclear units are extended into one-dimensional zigzag chains along the crystallographic c-axis via bridging L2 ligands, and further assembled into a two-dimensional supramolecular layer through hydrogen-bonding interactions involving lattice triethylamine and DMF molecules, ultimately forming a three-dimensional network. Both DMF and triethylamine molecules are disordered about a twofold rotation axis. This work highlights the structural directing roles of the fluoro-substituted multidentate Schiff base ligand and the rigid auxiliary ligand in the assembly of zinc(II) coordination polymers. Full article

(This article belongs to the Section Structure Determination)

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5 pages, 1329 KB

Open AccessShort Note

(5aS,8R,9aR)-5,5,8-Trimethyloctahydrobenzo[f][1,4]oxazepin-3(2H)-one

by Nikolai S. Li-Zhulanov, Dmitrii D. Golovchenko, Tatyana V. Rybalova, Maria E. Modelskaya, Artem D. Rogachev, Konstantin P. Volcho and Nariman F. Salakhutdinov

Molbank 2026, 2026(5), M2225; https://doi.org/10.3390/M2225 - 1 Sep 2026

The monoterpene-derived 1,4-oxazepan-3-one, (5aS,8R,9aR)-5,5,8-trimethyloctahydrobenzo[f][1,4]oxazepin-3(2H)-one, was synthesized from the corresponding (−)-isopulegol-based chloroacetamide by intramolecular cyclization in acetonitrile. The product was isolated in 70% yield as colorless crystals. Its structure was established by one- and [...] Read more.

The monoterpene-derived 1,4-oxazepan-3-one, (5aS,8R,9aR)-5,5,8-trimethyloctahydrobenzo[f][1,4]oxazepin-3(2H)-one, was synthesized from the corresponding (−)-isopulegol-based chloroacetamide by intramolecular cyclization in acetonitrile. The product was isolated in 70% yield as colorless crystals. Its structure was established by one- and two-dimensional NMR spectroscopy and high-resolution mass spectrometry and was confirmed by single-crystal X-ray diffraction analysis. The transformation provides concise access to a fused bicyclic 1,4-oxazepan-3-one bearing a stereochemically defined para-menthane scaffold. Full article

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Graphical abstract

8 pages, 922 KB

Open AccessShort Note

2-([1,1′-Biphenyl]-4-yl)-2,3,4,5-tetrahydro-1H-benzo[c]azepin-1-one

by Yuki Sawatari, Kazunobu Igawa, Eiji Tsurumaki and Gen-ichi Konishi

Molbank 2026, 2026(4), M2223; https://doi.org/10.3390/M2223 - 18 Aug 2026

The previously unreported seven-membered-ring benzanilide derivative, 2-([1,1′-biphenyl]-4-yl)-2,3,4,5-tetrahydro-1H-benzo[c]azepin-1-one (1), was synthesized and structurally characterized by spectroscopic methods and single-crystal X-ray diffraction analysis. The crystal structures of 1 and the known six-membered-ring analogue (2) were compared with [...] Read more.

The previously unreported seven-membered-ring benzanilide derivative, 2-([1,1′-biphenyl]-4-yl)-2,3,4,5-tetrahydro-1H-benzo[c]azepin-1-one (1), was synthesized and structurally characterized by spectroscopic methods and single-crystal X-ray diffraction analysis. The crystal structures of 1 and the known six-membered-ring analogue (2) were compared with that of the corresponding five-membered-ring analogue (3). Increasing ring size was found to induce steric distortions around the amide moiety, resulting in systematic changes in the π-conjugation with the adjacent phenyl groups. This study establishes a structural basis for controlling the electronic properties of ring-fixed benzanilides through ring-size engineering. Full article

(This article belongs to the Section Structure Determination)

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8 pages, 1498 KB

Open AccessShort Note

5-Cyano-7-(2-hydroxyphenyl)-4-[(2-hydroxyphenyl)amino]pyrrolo[2,3-c][1,2,6]thiadiazin-6(7H)-iminium Chloride Hydrate

by Andreas S. Kalogirou, Andreas Kourtellaris and Panayiotis A. Koutentis

Molbank 2026, 2026(4), M2222; https://doi.org/10.3390/M2222 - 18 Aug 2026

Reaction of 2-(3,5-dichloro-4H-1,2,6-thiadiazin-4-ylidene)malononitrile with sodium 2-aminophenolate (1.5 equiv.) in anhydrous THF at ca. 0–20 °C afforded the known 4-chlorobenzo[5,6][1,4]oxazino[2,3-c][1,2,6]thiadiazine in 76% yield. In contrast, treatment of the same substrate with 2-aminophenol (3 equiv.) in acetonitrile at ca. [...] Read more.

Reaction of 2-(3,5-dichloro-4H-1,2,6-thiadiazin-4-ylidene)malononitrile with sodium 2-aminophenolate (1.5 equiv.) in anhydrous THF at ca. 0–20 °C afforded the known 4-chlorobenzo[5,6][1,4]oxazino[2,3-c][1,2,6]thiadiazine in 76% yield. In contrast, treatment of the same substrate with 2-aminophenol (3 equiv.) in acetonitrile at ca. 20 °C gave 5-cyano-7-(2-hydroxyphenyl)-4-[(2-hydroxyphenyl)amino]pyrrolo[2,3-c][1,2,6]thiadiazin-6(7H)-iminium chloride hydrate in 93% yield. This compound was characterized by ¹H and ¹³C NMR, IR and UV-vis and mass spectrometry, together with melting point and elemental analysis, and its structure was supported by single-crystal X-ray crystallography. Full article

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Figure 1

6 pages, 901 KB

Open AccessShort Note

4-Methyl-N-(2-methylbenzyl)-N′-(2-methylbenzylidene)benzenesulfonohydrazide

by Lei Gao, Yue Zhang and Xiaoxu Tan

Molbank 2026, 2026(4), M2219; https://doi.org/10.3390/M2219 - 17 Aug 2026

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 [...] Read more.

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. Full article

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10 pages, 2430 KB

Open AccessCommunication

Synthesis and Structure of Palladium(II) Complex with (2E)-2-[1-(4-Aminophenyl)ethylidene]hydrazine-1-carbothioamide

by Daria S. Levchenko, Artem S. Igonin, Ekaterina I. Isaeva, Ruslan I. Baichurin, Oleg P. Demidov and Sergey V. Makarenko

Molbank 2026, 2026(4), M2221; https://doi.org/10.3390/M2221 - 17 Aug 2026

This work presents the synthesis and structural characterization of a previously unknown palladium(II) complex with (2E)-2-[1-(4-aminophenyl)ethylidene]hydrazine-1-carbothioamide, which in the solid state forms a highly symmetric tetrametallic metallamacrocycle. The structure of the synthesized (2E)-2-[1-(4-aminophenyl)ethylidene]hydrazine-1-carbothioamide and corresponding palladium(II) complex was established [...] Read more.

This work presents the synthesis and structural characterization of a previously unknown palladium(II) complex with (2E)-2-[1-(4-aminophenyl)ethylidene]hydrazine-1-carbothioamide, which in the solid state forms a highly symmetric tetrametallic metallamacrocycle. The structure of the synthesized (2E)-2-[1-(4-aminophenyl)ethylidene]hydrazine-1-carbothioamide and corresponding palladium(II) complex was established by ¹H, ¹³C–{¹H}, ¹H–¹³C HMQC, and ¹H–¹³C HMBC NMR spectroscopy; IR and UV spectroscopy; mass spectrometry; TGA/DSC analyses; and single-crystal X-ray diffraction. Full article

(This article belongs to the Section Structure Determination)

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6 pages, 320 KB

Open AccessShort Note

1-[(4S)-4-Benzyl-1,3-oxazolidin-2-one-3-yl]propyltriphenylphosphonium Tetrafluoroborate

by Jakub Adamek, Natalia Sępek and Agnieszka Październiok-Holewa

Molbank 2026, 2026(4), M2220; https://doi.org/10.3390/M2220 - 17 Aug 2026

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 [...] Read more.

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. Full article

(This article belongs to the Section Organic Synthesis and Biosynthesis)

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Scheme 1

4 pages, 607 KB

Open AccessShort Note

2-(4H-Indeno[2,1-d][1,2,3]thiadiazol-4-ylidene)-1H-indene-1,3(2H)-dione

by Sofia D. Usova, Ekaterina A. Knyazeva, Ludmila V. Mikhalchenko and Oleg A. Rakitin

Molbank 2026, 2026(4), M2218; https://doi.org/10.3390/M2218 - 14 Aug 2026

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-(4 [...] Read more.

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. Full article

(This article belongs to the Collection Heterocycle Reactions)

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Figure 1

4 pages, 285 KB

Open AccessShort Note

2,3-Dihydro-5H-imidazo [2,1-b][1,3]thiazin-5-one

by Nataliia Slyvka, Lesya Saliyeva, Dmytro Khylyuk, Serhii Holota and Mykhailo Vovk

Molbank 2026, 2026(4), M2217; https://doi.org/10.3390/M2217 - 12 Aug 2026

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. [...] Read more.

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. Full article

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6 pages, 613 KB

Open AccessShort Note

(±)-2-Chloro-N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-2-phenylacetamide

by Diyana Dimitrova, Stanimir Manolov, Iliyan Ivanov, Dimitar Bojilov and Paraskev Nedialkov

Molbank 2026, 2026(4), M2216; https://doi.org/10.3390/M2216 - 12 Aug 2026

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 ¹ [...] Read more.

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. Full article

(This article belongs to the Section Structure Determination)

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7 pages, 796 KB

Open AccessShort Note

(1E,4E)-1,5-Bis(2,4-dichlorophenyl)penta-1,4-dien-3-one Oxime

by Juan P. Montaño, Andres F. Sánchez and Rodrigo Abonia

Molbank 2026, 2026(4), M2215; https://doi.org/10.3390/M2215 - 6 Aug 2026

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 [...] Read more.

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. Full article

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7 pages, 517 KB

Open AccessShort Note

Methyl 6-(2,3-Dimethoxybenzamido)-2,3-dihydroxybenzoate

by Guo-Li Li, Zhi-Dong Yu, Na Gao, Hong-Ying Yang, Yi-Lin He and Tong Shen

Molbank 2026, 2026(4), M2213; https://doi.org/10.3390/M2213 - 4 Aug 2026

Gymnaconitum gymnandrum, a Tibetan medicinal herb, is distributed across high-altitude regions of China. Despite its high toxicity, it exhibits analgesic, anti-inflammatory, antitumor, and other pharmacological activities. It is used topically for skin conditions and orally for rheumatism. Its main bioactive components are [...] Read more.

Gymnaconitum gymnandrum, a Tibetan medicinal herb, is distributed across high-altitude regions of China. Despite its high toxicity, it exhibits analgesic, anti-inflammatory, antitumor, and other pharmacological activities. It is used topically for skin conditions and orally for rheumatism. Its main bioactive components are alkaloids. A new organic amine alkaloid has been isolated from the plant and structurally identified using HRMS, NMR, and X-ray diffraction. Full article

(This article belongs to the Section Natural Product Chemistry)

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4 pages, 336 KB

Open AccessShort Note

Bis([1,2,5]thiadiazolo)[3,4-f:3′,4′-h]quinoxaline-8,9-dicarbonitrile

by Anastasiya S. Yushkova, Ekaterina A. Knyazeva and Oleg A. Rakitin

Molbank 2026, 2026(4), M2214; https://doi.org/10.3390/M2214 - 4 Aug 2026

Compounds containing electron-withdrawing dicyanopyrazine and 1,2,5-chalcogenadiazole fragments are promising for the design of magnetic and optoelectronic materials. In this paper, bis([1,2,5]thiadiazolo)[3,4-f:3′,4′-h]quinoxaline-8,9-dicarbonitrile was prepared via Körner–Hinsberg condensation of benzo[1,2-c:3,4-c′]bis([1,2,5]thiadiazole)-4,5-dione with 2,3-diaminomaleonitrile in the presence of catalytic amounts of TsOH in refluxing ethanol. The structure [...] Read more.

Compounds containing electron-withdrawing dicyanopyrazine and 1,2,5-chalcogenadiazole fragments are promising for the design of magnetic and optoelectronic materials. In this paper, bis([1,2,5]thiadiazolo)[3,4-f:3′,4′-h]quinoxaline-8,9-dicarbonitrile was prepared via Körner–Hinsberg condensation of benzo[1,2-c:3,4-c′]bis([1,2,5]thiadiazole)-4,5-dione with 2,3-diaminomaleonitrile in the presence of catalytic amounts of TsOH in refluxing ethanol. The structure of the newly synthesized compound was established via elemental analysis, mass spectrometry, ¹³C NMR, and IR spectroscopy. Full article

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Graphical abstract

11 pages, 3119 KB

Open AccessCommunication

N-Demethyl-N-nitrosolevofloxacin

by Claudio Maestri, Mattia Lopresti, Ivana Miletto, Attila Benyei, Marzia Petreti, Luisa Zangirolami, Camilla Cavallotti and Giovanni B. Giovenzana

Molbank 2026, 2026(4), M2211; https://doi.org/10.3390/M2211 - 4 Aug 2026

Levofloxacin is an antibiotic belonging to the fluoroquinolone family. N-Demethyllevofloxacin, a metabolite and an impurity of levofloxacin, features a secondary amine that is susceptible to N-nitrosation, raising concerns about the formation of a potentially toxic nitrosamine. The corresponding N-nitrosamine was [...] Read more.

Levofloxacin is an antibiotic belonging to the fluoroquinolone family. N-Demethyllevofloxacin, a metabolite and an impurity of levofloxacin, features a secondary amine that is susceptible to N-nitrosation, raising concerns about the formation of a potentially toxic nitrosamine. The corresponding N-nitrosamine was synthesized in two steps and characterized using HRMS, NMR spectroscopy, IR spectroscopy, UV absorption and emission spectroscopies and powder X-ray diffraction. This work provides a reliable reference for the quantitation and control of nitrosamine impurities associated with levofloxacin in chemical and pharmaceutical contexts. Full article

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Graphical abstract

5 pages, 326 KB

Open AccessShort Note

(Z)-3′-(3-Chloro-4-fluorophenyl)-5-fluoro-5′-((6-methoxypyridin-3-yl)methylene)spiro[indoline-3,2′-thiazolidine]-2,4′-dione

by Dominika Kuceł, Jarosław Sobstyl, Serhii Holota and Dmytro Khylyuk

Molbank 2026, 2026(4), M2212; https://doi.org/10.3390/M2212 - 4 Aug 2026

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 [...] Read more.

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. Full article

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Scheme 1

9 pages, 1942 KB

Open AccessCommunication

A New Bis(8-hydroxyquinolinylmethyl) Perhydrobenzimidazole Obtained from a Cyclic Aminal Derived from trans-1,2-Diaminocyclohexane and 8-Hydroxyquinoline

by Augusto Rivera, Jaime Ríos-Motta and Diego Quiroga

Molbank 2026, 2026(4), M2209; https://doi.org/10.3390/M2209 - 3 Aug 2026

The reaction of 8-hydroxyquinoline and (2R,7R,11S,16S)-1,8,10,17-tetraazapentacyclo [8.8.1.1.^8,170.^2,70.^11,16]icosane under Mannich-type conditions afforded a new quinoline-functionalized diazabicyclic derivative in 27% yield. The structure of the product was established by FT-IR, ¹H and ¹³C NMR, HSQC, HMBC, and [...] Read more.

The reaction of 8-hydroxyquinoline and (2R,7R,11S,16S)-1,8,10,17-tetraazapentacyclo [8.8.1.1.^8,170.^2,70.^11,16]icosane under Mannich-type conditions afforded a new quinoline-functionalized diazabicyclic derivative in 27% yield. The structure of the product was established by FT-IR, ¹H and ¹³C NMR, HSQC, HMBC, and ESI-MS analyses, which confirmed the connectivity between the two quinoline units and the perhydrobenzimidazole heterocyclic fragment. The conformational strain of the perhydroimidazolidine fragment prevents the rearrangement pathway previously reported for related systems, such as cyclic aminal 1,3,6,8-tetraazatricyclo [4.4.1.1^3,8]dodecane (TATD), leading to a different reaction outcome. The results demonstrate that the conformationally constrained aminal exhibits reactivity distinct from that reported for TATD-derived systems, providing new insight into the behavior of cyclic aminals in Mannich-type reactions. Full article

(This article belongs to the Collection Heterocycle Reactions)

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Open AccessCorrection

Correction: Pasdar et al. Eco-Friendly Synthesis of Perimidine Derivatives Using Recyclable Fe₃O₄@Nano-Cellulose/Ti(IV). Molbank 2026, 2026, M2181

by Ghaffar Pasdar, Abdolhamid Bamoniri and Bi Bi Fatemeh Mirjalili

Molbank 2026, 2026(4), M2208; https://doi.org/10.3390/M2208 - 3 Aug 2026

In the original publication [...] Full article

(This article belongs to the Collection Heterocycle Reactions)

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