Molbank

4 pages, 418 KB

Open AccessShort Note

1α-Methoxy-3-oxo-8α-hydroxy-10αH-eremophila-7(11)-en-12,8β-olide from Ligularia fischeri

by Xiangrong Zhang, Dingkuo Liu, Fang Liu, Cheng Yang, Jingjing Gao and Chunfeng Xie

Molbank 2026, 2026(3), M2193; https://doi.org/10.3390/M2193 - 12 Jun 2026

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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. Full article

(This article belongs to the Section Natural Product Chemistry)

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6 pages, 1063 KB

Open AccessShort Note

4-Methyl-N-(4-methylbenzyl)-N’-(4-methylbenzylidene) benzenesulfonohydrazide

by Yue Zhang, Xiangrong Wang, Zhihan Liu, Zheng Zhang, Xiaoxu Tan and Lei Gao

Molbank 2026, 2026(3), M2192; https://doi.org/10.3390/M2192 - 9 Jun 2026

Viewed by 343

Abstract

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 [...] Read more.

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. Full article

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7 pages, 804 KB

Open AccessShort Note

Uranyl Complex of 1,3-bis(ditertbutylphosphinoxidomethyl)benzene

by Maha M. Alotaibi, Md Abdul Goni, Eric Reinheimer and Tasneem A. Siddiquee

Molbank 2026, 2026(3), M2191; https://doi.org/10.3390/M2191 - 9 Jun 2026

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Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Section Structure Determination)

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Graphical abstract

1 pages, 133 KB

Open AccessCorrection

Correction: Chen et al. N-(2,5-Difluorobenzylidene)-1-(2,5-difluorobenzyl)methanimine. Molbank 2026, 2026, M2174

by Tiffany L. Chen, Manisha Sharma and Nicholas E. Leadbeater

Molbank 2026, 2026(3), M2190; https://doi.org/10.3390/M2190 - 9 Jun 2026

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Abstract

There was an error in the original publication [...] Full article

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

12 pages, 1728 KB

Open AccessShort Note

2-Chloro-4,5,6,7-tetrafluoro-2-(methylthio)-1H-indene-1,3(2H)-dione

by Anastasia R. Kovrizhina and Andrei I. Khlebnikov

Molbank 2026, 2026(3), M2189; https://doi.org/10.3390/M2189 - 8 Jun 2026

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Abstract

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 [...] Read more.

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. Full article

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

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10 pages, 2778 KB

Open AccessShort Note

2-((((R)-3-(((9E,17Z)-18-Bromooctadeca-9,17-dien-7,15-diynoyl)oxy)-2-hydroxypropoxy)(hydroxy)phosphoryl)oxy)-N,N,N-trimethylethan-1-aminium

by Abdu Al Nashrey, Emmanuel T. Oluwabusola, Hussin D. Almalki, Gagan Preet, Dawrin Pech-Puch, Abel M. Forero, Jaime Rodriguez, Rainer Ebel and Marcel Jaspars

Molbank 2026, 2026(3), M2188; https://doi.org/10.3390/M2188 - 5 Jun 2026

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Abstract

The Saudi Arabian Red Sea has been a focus of ongoing scientific exploration due to its extensive, largely untapped marine biodiversity, particularly marine sponges. Marine sponges have long been recognised as a valuable source of unique compounds. In this study, we isolated a [...] Read more.

The Saudi Arabian Red Sea has been a focus of ongoing scientific exploration due to its extensive, largely untapped marine biodiversity, particularly marine sponges. Marine sponges have long been recognised as a valuable source of unique compounds. In this study, we isolated a new brominated compound (1) from the marine sponge Aiolochroia crassa, collected from the Saudi Arabian Sea, using chromatographic analyses. Molecular networking analysis revealed the presence of brominated molecules in the extract. The identified compound belongs to a class of phosphatidylcholine derivatives. The structure of compound 1 was elucidated using 1D and 2D NMR spectroscopy and high-resolution ESI-Q-TOF mass spectrometry. Further structure confirmation studies were performed using MS/MS fragmentation analysis and DFT calculations for the ¹H and ¹³C NMR chemical shifts. This is the first report of 1 from this species of marine sponges. Full article

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5 pages, 355 KB

Open AccessShort Note

(2R,3R,4S,5R,6S,8R,13R,16S,17R)-11-Ethyl-13-methyl-4,6,8,9,16-pentamethoxy-11-azahexacyclo[7.7.2.1^2,5.0^1,10.0^3,8.0^13,17]nonadecane

by Na Gao, Guo-Li Li, Lei Wang, Hong-Ying Yang, Yi-Lin He and Tong Shen

Molbank 2026, 2026(3), M2187; https://doi.org/10.3390/M2187 - 5 Jun 2026

Viewed by 240

Abstract

The Delphinium albocoeruleum Maxim is a perennial herbaceous plant of the Ranunculaceae family, genus Delphinium. It typically grows in well-drained alpine meadows or shrublands at elevations of 2500–4000 m, which shapes the species’ unique environmental adaptation mechanism and endows it with high [...] Read more.

The Delphinium albocoeruleum Maxim is a perennial herbaceous plant of the Ranunculaceae family, genus Delphinium. It typically grows in well-drained alpine meadows or shrublands at elevations of 2500–4000 m, which shapes the species’ unique environmental adaptation mechanism and endows it with high medicinal value. There are a few reports on the chemical constituents and biological activities of this plant. Therefore, this study focuses on the chemical constituents of the plant in order to discover structurally novel alkaloids. This paper reports on the isolation and structural characterization, using HRMS and 1D and 2D NMR, of a new alkaloid that came from the plant. Full article

(This article belongs to the Section Natural Product Chemistry)

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6 pages, 681 KB

Open AccessShort Note

3-(Methylthio)-1-[(4-nitrophenyl)sulfonyl]-1H-1,2,4-triazol-5-amine

by Diana Becerra, Mario A. Macías and Juan-Carlos Castillo

Molbank 2026, 2026(3), M2186; https://doi.org/10.3390/M2186 - 5 Jun 2026

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Abstract

We report a highly chemoselective N-sulfonylation of 3-(methylthio)-1H-1,2,4-triazol-5-amine with 4-nitrobenzenesulfonyl chloride promoted by N,N-diisopropylethylamine in acetonitrile under mild conditions. This transformation selectively affords N-(4-nitrophenyl)sulfonylation at the N1 position of the 1,2,4-triazole ring over the exocyclic amine [...] Read more.

We report a highly chemoselective N-sulfonylation of 3-(methylthio)-1H-1,2,4-triazol-5-amine with 4-nitrobenzenesulfonyl chloride promoted by N,N-diisopropylethylamine in acetonitrile under mild conditions. This transformation selectively affords N-(4-nitrophenyl)sulfonylation at the N1 position of the 1,2,4-triazole ring over the exocyclic amine functionality. The product was fully characterized by IR, 1D and 2D NMR spectroscopy, as well as high-resolution mass spectrometry, unequivocally confirming its molecular structure. Full article

(This article belongs to the Collection Heterocycle Reactions)

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9 pages, 664 KB

Open AccessCommunication

A Three-Step Synthesis of (3aR,7aR)-1,3-bis(4-Aminobenzyl)octahydro-2H-benzo[d]imidazole-2-thione from trans-(R, R)-diaminocyclohexane

by Catalina Hoyos-Orozco, Ericsson Coy-Barrera and Diego Quiroga

Molbank 2026, 2026(3), M2185; https://doi.org/10.3390/M2185 - 4 Jun 2026

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Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Section Structure Determination)

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8 pages, 334 KB

Open AccessCommunication

Development of New Aryl-Substituted 1,2,3-Triazole Derivatives of Celastrol: Synthetic Approaches and Structural Characterization

by Yuhan Xie, Nayara Macêdo Peixoto Araujo, Stanislau Bogusz Junior, Deepa Alex and Paolo Coghi

Molbank 2026, 2026(3), M2184; https://doi.org/10.3390/M2184 - 3 Jun 2026

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Abstract

In this report, we describe the synthesis of two new celastrol derivatives featuring aryl-substituted 1,2,3-triazole fragments attached to the celastrol scaffold via an ester linkage. The target compounds, incorporating 4-methoxyphenyl and p-tert-butylphenyl groups, were characterized by ¹H and ¹³C NMR [...] Read more.

In this report, we describe the synthesis of two new celastrol derivatives featuring aryl-substituted 1,2,3-triazole fragments attached to the celastrol scaffold via an ester linkage. The target compounds, incorporating 4-methoxyphenyl and p-tert-butylphenyl groups, were characterized by ¹H and ¹³C NMR spectroscopy, FTIR, UV-Vis, HRMS, melting point determination, and specific rotation measurements. Full article

(This article belongs to the Section Natural Product Chemistry)

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7 pages, 974 KB

Open AccessCommunication

Synthesis and Structures of Trifluoromethylborates [pinB(Aryl)CF₃]⁻: pinB = 4,4,5,5-Tetramethyl-1,3,2-dioxaborolane

by Yu-En Huang and Shigekazu Ito

Molbank 2026, 2026(3), M2183; https://doi.org/10.3390/M2183 - 2 Jun 2026

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Abstract

Fluoroalkyl-substituted organoboron compounds are valuable building blocks for organic synthesis and for the development of functional molecules in medicinal chemistry, agrochemicals, and materials science. Building on our previous work on difluoromethyl-substituted borates, we report the synthesis and structural characterization of trifluoromethylated borates, 2-aryl-4,4,5,5-tetramethyl-2-(trifluoromethyl)-1,3,2-dioxaborolan-2-uide [...] Read more.

Fluoroalkyl-substituted organoboron compounds are valuable building blocks for organic synthesis and for the development of functional molecules in medicinal chemistry, agrochemicals, and materials science. Building on our previous work on difluoromethyl-substituted borates, we report the synthesis and structural characterization of trifluoromethylated borates, 2-aryl-4,4,5,5-tetramethyl-2-(trifluoromethyl)-1,3,2-dioxaborolan-2-uide salts ([pinB(Aryl)CF₃]⁻). Treatment of pinB–Aryl boronates (pinB = 4,4,5,5-tetramethyl-1,3,2-dioxaborolane) with trimethyl(trifluoromethyl)silane (Ruppert–Prakash reagent) in the presence of potassium tert-butoxide and 18-crown-6 ether (18-C-6) afforded the corresponding trifluoromethylated borates as isolable crystalline compounds. Compared with the related difluoromethylated borates, the CF₃ substituent increases the tendency of [pinB(Aryl)CF₃]⁻ to exhibit hygroscopic behavior, as supported by a hydrated crystal structure and the formation of a hygroscopic product. The isolable trifluoromethylborates can serve as reservoirs of electrophilic trifluoromethyl radicals upon oxidation. Full article

(This article belongs to the Section Structure Determination)

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8 pages, 812 KB

Open AccessShort Note

3-(Diphenylamino)-4-ethoxycyclobut-3-ene-1,2-dione

by Nathan Long, Emanuela Paval, Joseph C. Bear, Jeremy K. Cockcroft and Stephen P. Wren

Molbank 2026, 2026(3), M2182; https://doi.org/10.3390/M2182 - 25 May 2026

Viewed by 470

Abstract

The title compound, 3-(diphenylamino)-4-ethoxycyclobut-3-ene-1,2-dione (6), was prepared by reaction of diphenylamine (2) with diethyl squarate (DES; 5) as part of our ongoing studies on monosquarate-amides. Following purification and recrystallisation, the product was isolated as a green crystalline solid. [...] Read more.

The title compound, 3-(diphenylamino)-4-ethoxycyclobut-3-ene-1,2-dione (6), was prepared by reaction of diphenylamine (2) with diethyl squarate (DES; 5) as part of our ongoing studies on monosquarate-amides. Following purification and recrystallisation, the product was isolated as a green crystalline solid. Its structure was established by spectroscopic methods, including FTIR, ¹H NMR, ¹³C NMR and HRMS, and was unambiguously confirmed by single-crystal X-ray diffraction. This work provides access to a previously unreported diphenylamino-substituted squaric acid derivative. Full article

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

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Graphical abstract

14 pages, 2722 KB

Open AccessCommunication

Eco-Friendly Synthesis of Perimidine Derivatives Using Recyclable Fe₃O₄@Nano-Cellulose/Ti(IV)

by Ghaffar Pasdar, Abdolhamid Bamoniri and Bi Bi Fatemeh Mirjalili

Molbank 2026, 2026(3), M2181; https://doi.org/10.3390/M2181 - 21 May 2026

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Abstract

A novel bio-capable method has been implemented for the synthesis of newly substituted derivatives of perimidine using Fe₃O₄@nano-cellulose/Ti(IV) as a magnetic, sustainable, and eco-friendly Lewis acid nanocatalyst. The catalyst was thoroughly characterized by XRD, FESEM, and TGA analyses, confirming [...] Read more.

A novel bio-capable method has been implemented for the synthesis of newly substituted derivatives of perimidine using Fe₃O₄@nano-cellulose/Ti(IV) as a magnetic, sustainable, and eco-friendly Lewis acid nanocatalyst. The catalyst was thoroughly characterized by XRD, FESEM, and TGA analyses, confirming its crystalline structure, uniform nanoscale morphology, and high thermal stability. The reaction proceeded smoothly in eco-friendly solvents, providing outstanding yields under mild and rapid conditions, especially with ultrasonics. The catalyst, derived from renewable materials, exhibited remarkable activity, easy magnetic recovery, and excellent reusability over several cycles without significant loss of efficiency. Spectral characterization, IR, ¹H NMR, ¹³C NMR, ¹⁹F NMR, and HRMS analyses verified that perimidine derivatives were synthesized properly. This sustainable and efficient approach demonstrates the prospect of green Lewis acid nanocatalysts for the sustainable synthesis of valuable heterocyclic compounds. Full article

(This article belongs to the Collection Heterocycle Reactions)

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6 pages, 235 KB

Open AccessCommunication

Synthesis and Characterization of Piperazine-Linked Eugenol Derivative

by Munishama Gowda Yenagunte Narayanaswamy, Sujeet Kumar, Siddamsetty Ramachandra Setty, Basavaraj Metikurki and Chaluvaraju Kalamuddanadoddi Chaluvegowda

Molbank 2026, 2026(3), M2180; https://doi.org/10.3390/M2180 - 20 May 2026

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Abstract

In the present work, we synthesize 2-(4-allyl-2-methoxyphenoxy)-1-(4-phenylpiperazin-1-yl)ethan-1-one, a semisynthetic derivative of the natural product eugenol. The compound was synthesized via a three-step synthetic pathway involving esterification, hydrolysis, and subsequent coupling with 4-phenylpiperazine, as confirmed by FTIR, ¹H NMR, ¹³C NMR, and [...] Read more.

In the present work, we synthesize 2-(4-allyl-2-methoxyphenoxy)-1-(4-phenylpiperazin-1-yl)ethan-1-one, a semisynthetic derivative of the natural product eugenol. The compound was synthesized via a three-step synthetic pathway involving esterification, hydrolysis, and subsequent coupling with 4-phenylpiperazine, as confirmed by FTIR, ¹H NMR, ¹³C NMR, and mass spectrometric data. Full article

(This article belongs to the Section Natural Product Chemistry)

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7 pages, 1191 KB

Open AccessCommunication

Preparative Enzymatic Desymmetrization of (Acetyl-Leu-Pro-Lys)₂-R110 Using Bovine Trypsin Variant D189S

by Sarah Stoppe, Marianne Hahn, Martin Dauner and Frank Bordusa

Molbank 2026, 2026(3), M2179; https://doi.org/10.3390/M2179 - 20 May 2026

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Abstract

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 [...] Read more.

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. Full article

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

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11 pages, 3273 KB

Open AccessShort Note

2-Methoxy-4-[5-(2-oxo-1,3-dioxolan-4-yl)-4,5-dihydroisoxazol-3-yl]phenyl 4-n-decyloxybenzoate

by Itamar Luís Gonçalves, Aloir Antonio Merlo, Bruna Thatise Batistel, Leonardo Rossner Wbatuba and Henrique de Aguiar Mello

Molbank 2026, 2026(3), M2178; https://doi.org/10.3390/M2178 - 13 May 2026

Viewed by 451

Abstract

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, [...] Read more.

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. Full article

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

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5 pages, 581 KB

Open AccessShort Note

2,2′-(Methylenebis(3,4-dimethoxy-6,1-phenylene))diacetic Acid

by Savina Stoyanova and Milen G. Bogdanov

Molbank 2026, 2026(3), M2177; https://doi.org/10.3390/M2177 - 11 May 2026

Viewed by 393

Abstract

The formation of side products is often unavoidable in organic synthesis; however, analyzing these secondary species provides practical insights into reaction pathways, mechanisms, and competing processes. This understanding is essential for optimizing reaction conditions, increasing product yields, and improving overall safety and efficiency. [...] Read more.

The formation of side products is often unavoidable in organic synthesis; however, analyzing these secondary species provides practical insights into reaction pathways, mechanisms, and competing processes. This understanding is essential for optimizing reaction conditions, increasing product yields, and improving overall safety and efficiency. Additionally, side products can sometimes reveal unexpected molecular structures with valuable properties. In this study, we present the characterization of a compound that formed as a side product in a modified Pictet-Spengler reaction. The molecular structure of 2,2′-(methylenebis(3,4-dimethoxy-6,1-phenylene))diacetic acid was elucidated using a combination of NMR, FTIR and UV–Vis spectroscopic techniques, as well as HRMS analysis. Full article

(This article belongs to the Collection Molecules from Side Reactions)

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8 pages, 987 KB

Open AccessCommunication

Crystal Structures of Two 4-Alkyl-8-hydroxyquinolines

by Sara Braun, Anke Schwarzer and Monika Mazik

Molbank 2026, 2026(3), M2176; https://doi.org/10.3390/M2176 - 11 May 2026

Viewed by 451

Abstract

4-Methyl- (1) and 4-ethyl-8-hydroxyquinoline (2) crystallize from a mixture of diethyl ether and chloroform in the triclinic space group P

\bar{1}

. X-ray analysis reveals that both compounds form discrete molecular dimers stabilized by intermolecular O-H∙∙∙N and C-H∙∙∙O [...] Read more.

4-Methyl- (1) and 4-ethyl-8-hydroxyquinoline (2) crystallize from a mixture of diethyl ether and chloroform in the triclinic space group P

\bar{1}

. X-ray analysis reveals that both compounds form discrete molecular dimers stabilized by intermolecular O-H∙∙∙N and C-H∙∙∙O hydrogen bonds, resulting in

R_{2}^{2} (5)

cyclic synthons. This pattern of hydrogen bonds is further stabilized by intramolecular O-H∙∙∙N bonds so that the quinoline nitrogen atom acts as a bifurcated binding site. The dimers exhibit a planar geometry and arrange into layer-like structures held together by π∙∙∙π stacking and van der Waals forces. While the fundamental bonding motifs are similar, the increased steric demand of the ethyl group in compound 2 induces a shift in the crystallographic orientation of the layers and alters the degree of π-overlap compared to the methyl-substituted analogue 1. Full article

(This article belongs to the Section Structure Determination)

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Graphical abstract

6 pages, 428 KB

Open AccessCommunication

Formation of a β-(3-Chlorobenzoyloxy)-α-hydroxyketone from a TBS-Protected Chalcone upon Oxidation with m-Chloroperbenzoic Acid

by Sonia Berenguel-Gómez, Irene Moreno-Gutiérrez, Jenifer Acien-García, Manuel Muñoz-Dorado, Míriam Álvarez-Corral and Ignacio Rodríguez-García

Molbank 2026, 2026(3), M2175; https://doi.org/10.3390/M2175 - 9 May 2026

Viewed by 356

Abstract

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 [...] Read more.

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. Full article

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

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Graphical abstract

4 pages, 1198 KB

Open AccessShort Note

N-(2,5-Difluorobenzylidene)-1-(2,5-difluorobenzyl)methanimine

by Tiffany L. Chen, Manisha Sharma and Nicholas E. Leadbeater

Molbank 2026, 2026(3), M2174; https://doi.org/10.3390/M2174 - 8 May 2026

Cited by 1 | Viewed by 385 | Correction

Abstract

The conversion of 2,5-difluorobenzylamine to N-(2,5-difluorobenzylidene)-1-(2,5-difluorobenzyl)methanimine using an oxoammonium salt bearing the nitrate anion is reported. The reaction is operationally simple, and the product is obtained with good yield. Full article

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

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Graphical abstract

5 pages, 499 KB

Open AccessShort Note

(R)-10-((((2-(3,4-Dihydroxyphenyl)-2-hydroxyethyl)(methyl)carbamoyl)oxy)methyl)-1,3,5,5,7,9-hexamethyl-5H-dipyrrolo[1,2-c:2′,1′-f][1,3,2]diazaborinin-4-ium-5-uide

by Mikhail A. Panfilov, Alexey Yu. Vorob’ev and Alexander E. Moskalensky

Molbank 2026, 2026(3), M2173; https://doi.org/10.3390/M2173 - 7 May 2026

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Abstract

The BODIPY core has emerged as a versatile scaffold for the design of photoremovable protecting groups (PPGs). Herein, we report the synthesis of a novel BODIPY–epinephrine conjugate linked via a carbamate moiety, enabling light-triggered release of the active compound (epinephrine, also known as [...] Read more.

The BODIPY core has emerged as a versatile scaffold for the design of photoremovable protecting groups (PPGs). Herein, we report the synthesis of a novel BODIPY–epinephrine conjugate linked via a carbamate moiety, enabling light-triggered release of the active compound (epinephrine, also known as adrenaline). The structure of the obtained product was confirmed by ¹H and M ¹³C NMR spectroscopy as well as high-resolution mass spectrometry (HRMS). The described conjugate represents a potential tool for the photoactivated modulation of biologically relevant processes. Full article

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6 pages, 378 KB

Open AccessShort Note

4-(6-Chloropyridin-3-yl)-6-cyclopropylpyrimidin-2-amine

by Yusen Wang, Jian Lv and Yukun Qin

Molbank 2026, 2026(3), M2172; https://doi.org/10.3390/M2172 - 6 May 2026

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Abstract

A novel nitrogen-containing heterocyclic compound, 4-(6-Chloropyridin-3-yl)-6-cyclopropylpyrimidin-2-amine, was designed and synthesized using 6-chloropyridin-3-aldehyde and cyclopropyl methyl ketone as starting materials. The structure of the target compound was characterized by ¹H NMR, ¹³C NMR and HRMS, and the spectral data were consistent with [...] Read more.

A novel nitrogen-containing heterocyclic compound, 4-(6-Chloropyridin-3-yl)-6-cyclopropylpyrimidin-2-amine, was designed and synthesized using 6-chloropyridin-3-aldehyde and cyclopropyl methyl ketone as starting materials. The structure of the target compound was characterized by ¹H NMR, ¹³C NMR and HRMS, and the spectral data were consistent with the expected structure, confirming the correctness of the product. Full article

(This article belongs to the Collection Heterocycle Reactions)

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7 pages, 429 KB

Open AccessCommunication

Synthesis of (Z)-6-Heneicosen-11-one, a Possible Pheromone Component of the Hickory Tussock Moth, Lophocampa caryae

by Peter Mayo and Sumudu Deepa Abeysekera

Molbank 2026, 2026(3), M2171; https://doi.org/10.3390/M2171 - 6 May 2026

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Abstract

The compound (Z)-6-heneicosen-11-one, a possible pheromone component of the hickory tussock moth, Lophocampa caryae, and a known pheromone component of the Douglas fir tussock moth, Orgyia pseudotsugata, was synthesized by a new four-step procedure with a 39% overall yield [...] Read more.

The compound (Z)-6-heneicosen-11-one, a possible pheromone component of the hickory tussock moth, Lophocampa caryae, and a known pheromone component of the Douglas fir tussock moth, Orgyia pseudotsugata, was synthesized by a new four-step procedure with a 39% overall yield and a six-step procedure incorporating a protecting group with a 28% overall yield. This new synthesis is comparable to other similar syntheses for this molecule in the literature. Full article

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

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10 pages, 662 KB

Open AccessCommunication

Synthesis of Three Bent Bis(imido-ferrocidiphenols)

by Pascal Pigeon

Molbank 2026, 2026(3), M2170; https://doi.org/10.3390/M2170 - 6 May 2026

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Abstract

The ferrocidiphenol family brings together anticancer molecules featuring a [ferrocene-alkene-(p-phenol)₂] motif that can form upon oxidation a quinone methide metabolite targeting cellular proteins. Adding an imide group (imido-ferrocidiphenol) dramatically enhanced the anticancer activity of ferrocidiphenol. We aimed to explore [...] Read more.

The ferrocidiphenol family brings together anticancer molecules featuring a [ferrocene-alkene-(p-phenol)₂] motif that can form upon oxidation a quinone methide metabolite targeting cellular proteins. Adding an imide group (imido-ferrocidiphenol) dramatically enhanced the anticancer activity of ferrocidiphenol. We aimed to explore whether molecules with two ferrociphenol motifs connected by bisimide moieties could provide even more effective compounds. Using amino-ferrocidiphenol and commercial bisanhydrides at reflux, for the first time, three symmetrical and bent bis(imido-ferrocidiphenols) were synthesized, with moderate yields, and characterized. However, these compounds were insoluble in most common organic solvents and unstable. This likely explains why their anticancer activity was nil. Full article

(This article belongs to the Collection Heterocycle Reactions)

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9 pages, 1489 KB

Open AccessCommunication

New Pyridinium Salt Bioconjugates of Cholesterol and Methylpyridine Derivatives: Synthesis and Characterization

by José María Peña-Martínez, Jesús Alberto Rojas Morales, Luis Ramiro Caso-Vargas, Elizabeth Bautista-Rodríguez, Joel L. Terán and Alan Carrasco-Carballo

Molbank 2026, 2026(3), M2169; https://doi.org/10.3390/M2169 - 2 May 2026

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Abstract

The synthesis of three novel, valuable bioconjugates obtained by coupling cholesterol bromoacetate with pyridine derivatives via an SN2 reaction was successfully carried out. Each of the products was fully characterized by magnetic nuclear resonance (¹H, ¹³C, APT, ¹H−¹ [...] Read more.

The synthesis of three novel, valuable bioconjugates obtained by coupling cholesterol bromoacetate with pyridine derivatives via an SN2 reaction was successfully carried out. Each of the products was fully characterized by magnetic nuclear resonance (¹H, ¹³C, APT, ¹H−¹H COSY, ¹H–¹³C HMBC, ¹H–¹³C HSQC), infrared spectroscopy (IR), and high-resolution mass spectrometry (HRMS). Full article

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

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8 pages, 991 KB

Open AccessCommunication

Synthesis of 2-(2-Methoxyphenyl)-4-methyl-6-nitroquinoline and 2-(2-Methoxyphenyl)-4-methylquinolin-6-amine

by Rumen Lyapchev, Maria Ivanova, Iskra Z. Koleva and Dimitar Shandurkov

Molbank 2026, 2026(3), M2168; https://doi.org/10.3390/M2168 - 30 Apr 2026

Viewed by 488

Abstract

A new compound, 2-(2-methoxyphenyl)-4-methyl-6-nitroquinoline, was obtained via Suzuki reaction. An unexpected side product, 2-(2-methoxyphenyl)-4-methylquinolin-6-amine, was isolated. The structures of the novel compounds were confirmed by ¹H, ¹³C and 2D-NMR. Their optical properties were also studied. Full article

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

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7 pages, 625 KB

Open AccessCommunication

Synthesis of (R)-(+)-3-(1-Hydroxyethylidene)-1-(1-phenylethyl)piperidine-2,4-dione, a Novel Tetramic Acid Analog

by Alan Aguilar-Aguilar, Ángel Palillero-Cisneros, Félix May-Moreno, Jorge R. Juarez-Posadas, Joel L. Terán and David M. Aparicio

Molbank 2026, 2026(3), M2167; https://doi.org/10.3390/M2167 - 27 Apr 2026

Viewed by 450

Abstract

Herein, starting from (R)-(+)-α-methylbenzylamine, we report an efficient synthesis and full characterization of a new (R)-3-(1-hydroxyethylidene)-1-(1-phenylethyl)piperidine-2,4-dione, a new tetramic acid analog. The key steps involved a non-classical Corey–Chaykovsky intramolecular cyclization reaction to access the corresponding zwitterion, followed by a [...] Read more.

Herein, starting from (R)-(+)-α-methylbenzylamine, we report an efficient synthesis and full characterization of a new (R)-3-(1-hydroxyethylidene)-1-(1-phenylethyl)piperidine-2,4-dione, a new tetramic acid analog. The key steps involved a non-classical Corey–Chaykovsky intramolecular cyclization reaction to access the corresponding zwitterion, followed by a sequential desulfurization/reduction and condensation procedure. The titled product was obtained in five steps, and the desired product 7 with an overall 58% yield. Full article

(This article belongs to the Collection Heterocycle Reactions)

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Molbank, Volume 2026, Issue 3 (June 2026) – 27 articles

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