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Organics, Volume 4, Issue 2 (June 2023) – 14 articles

Cover Story (view full-size image): The Nenitzescu reaction is a condensation reaction between an enamine and a quinone, most commonly resulting in 5-hydroxyindoles and 5-hydroxybenzofurans with promising bioactivities. Despite the high chemodivergency for this reaction, it remains of interest due to the mild reaction conditions, easily accessible starting materials and simple reaction procedures. Earlier investigation of the Nenitzescu reaction of piperazinone enaminoesters led to rearranged 2-imidazolidinone benzofurans. In this work, we aimed to develop reaction conditions that favor the formation of 5-hydroxyindoles via an extensive, multi-variate optimization study. This led to valuable insights into the parameters that influence regio- and chemoselectivity. Furthermore, two novel products were obtained, pyrrolo[2,3-f]indole and 2-benzofuranone. View this paper
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16 pages, 2366 KiB  
Article
Structural and Dynamic Behaviour of Heterocycles Derived from Ethylenediamines with Formaldehyde: 1,3,5-Triazinanes and Bis(imidazolidinyl)methanes
by Raúl Colorado-Peralta, Sonia Araceli Sánchez-Ruiz and Angelina Flores-Parra
Organics 2023, 4(2), 297-312; https://doi.org/10.3390/org4020024 - 15 Jun 2023
Viewed by 1125
Abstract
Formaldehyde is a simple chemical compound that is used as a building block in obtaining a wide range of products. The versatility of formaldehyde in chemical synthesis becomes evident when it is reacted with N-alkylethylenediamines. Therefore, this paper reports the structure and [...] Read more.
Formaldehyde is a simple chemical compound that is used as a building block in obtaining a wide range of products. The versatility of formaldehyde in chemical synthesis becomes evident when it is reacted with N-alkylethylenediamines. Therefore, this paper reports the structure and reactivity of a series of compounds derived from easily accessible molecules, such as formaldehyde, sodium hydrosulphide, and N-alkylethylenediamines. The 1,3,5-triazines (1a-1d) and bis(3-alkyl-imidazolidin-1-yl)methanes (2a-2d) were obtained by simple reaction conditions. Additionally, different proportions of sodium hydrosulphide and formaldehyde were used with N-benzylamine to obtain N-benzyltriazinane (3), N-benzylthiadiazinane (4) and N-benzyldithiazinane (5). All these compounds were characterized by analytical, spectroscopic, and spectrometric techniques, such as melting point, solubility, one-dimensional and two-dimensional nuclear magnetic resonance (13C, 1H, 15N, COSY, HETCOR, NOESY, COLOC), elemental analysis, high- and low-resolution mass spectrometry, among others. The structures of compounds 4 and 5 were obtained by single-crystal X-ray diffraction. The results show that small variations in the stoichiometry and the reaction conditions significantly influence the products obtained. Full article
(This article belongs to the Collection Advanced Research Papers in Organics)
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8 pages, 1600 KiB  
Communication
Palladium Catalyzed Allylic C-H Oxidation Enabled by Bicyclic Sulfoxide Ligands
by Yuming Wen, Jianfeng Zheng, Alex H. Evans and Qiang Zhang
Organics 2023, 4(2), 289-296; https://doi.org/10.3390/org4020023 - 13 Jun 2023
Viewed by 1356
Abstract
The activation of C-H bonds is a potent tool for modifying molecular structures in chemistry. This article details the steps involved in a novel ligand bearing a bicyclic [3.3.1]-nonane framework and bissulfoxide moiety. A palladium catalyzed allylic C-H oxidation method enables a direct [...] Read more.
The activation of C-H bonds is a potent tool for modifying molecular structures in chemistry. This article details the steps involved in a novel ligand bearing a bicyclic [3.3.1]-nonane framework and bissulfoxide moiety. A palladium catalyzed allylic C-H oxidation method enables a direct benzyl-allylic functionalization with the bissulfoxide ligand. Bissulfoixde ligand possesses a rapidly constructed bicyclic [3.3.1] framework and it proved to be effective for enabling both N- and C-alkylation. A total of 13 C-H activation productions were reported with good to excellent yields. This report validated that it is necessary to include bissulfoxide as a ligand for superior reactivities. Naftifine was produced utilizing developed C-H functionalization methodology in good overall yields. Full article
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12 pages, 4607 KiB  
Review
Hydrogen-Bonding Secondary Coordination Sphere Effect on CO2 Reduction
by Anamarija Briš and Davor Margetić
Organics 2023, 4(2), 277-288; https://doi.org/10.3390/org4020022 - 5 Jun 2023
Viewed by 1478
Abstract
Great efforts of the scientific community are focused on the development of catalysts for the reduction of carbon dioxide (CO2) to useful molecules such as carbon monoxide, formic acid, methanol, ethanol, methane, ethylene, or acetate. Various metal porphyrin complexes were synthesized [...] Read more.
Great efforts of the scientific community are focused on the development of catalysts for the reduction of carbon dioxide (CO2) to useful molecules such as carbon monoxide, formic acid, methanol, ethanol, methane, ethylene, or acetate. Various metal porphyrin complexes were synthesized and studied to develop highly active and selective catalysts. While the substituents on the porphyrin core (the primary coordination sphere) determine the reactivity of the metal, the introduction of the secondary coordination is important for the binding and activation of CO2. In this review, selected examples of iron porphyrin catalysts with a secondary coordination sphere capable of stabilizing intermediates of the CO2 reduction process by hydrogen bonding are presented. Full article
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12 pages, 4352 KiB  
Article
The Use of a Natural Polysaccharide as a Solidifying Agent and Color-Fixing Agent on Modern Paper and Historical Materials
by Lucia Emanuele, Tanja Dujaković, Graziella Roselli, Simone Campanelli and Giulia Bellesi
Organics 2023, 4(2), 265-276; https://doi.org/10.3390/org4020021 - 2 Jun 2023
Cited by 1 | Viewed by 1259
Abstract
This article presents results on the use of a new material as a solidifying agent and/or color-fixing agent. A special polysaccharide material extracted from the prickly pear cactus (Opuntia ficus indica) was tested on historical materials and modern papers. An old book from [...] Read more.
This article presents results on the use of a new material as a solidifying agent and/or color-fixing agent. A special polysaccharide material extracted from the prickly pear cactus (Opuntia ficus indica) was tested on historical materials and modern papers. An old book from the 18th century was chosen as historical material. From the mentioned book 42 pages were taken, on which a conservation and restoration pretreatment was performed before applying the polysaccharide material: sampling, fiber analysis, dry cleaning, ink solubility, pH test, thickness measurement and wet cleaning. The paper sheets provided for the test were divided into 4 groups, 3 of which were treated with gel and one left untreated as a reference. The division into groups is not only due to the different method of application, but also due to the process of gel extraction. The effect of the treatment was analyzed using FTIR-ATR. To test the mucilage as color-fixing agent 2 samples were prepared using watercolor papers colored with 6 different watercolors applied to 2.5 cm2 samples for each color in two rows of different intensity. One of the 2 samples was treated with gel, but both were immersed for 3 times in a water-ethanol solution for approximately 20 min as is standard practice in conservation and restoration. After washing, both specimens were subjected to colorimetric analysis to assess their differences. The results provided satisfactory evidence for the protection of paints sensitive to aqueous treatments and suggest the use of mucilage as a new material in cleaning method for water-soluble media. Full article
(This article belongs to the Collection Advanced Research Papers in Organics)
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14 pages, 10416 KiB  
Article
Facile Photochemical/Thermal Assisted Hydration of Alkynes Catalysed under Aqueous Media by a Chalcogen Stabilized, Robust, Economical, and Reusable Fe3Se2(CO)9 Cluster
by Munsaf Ali, Avinash K. Srivastava, Nitinkumar Satyadev Upadhyay, Naveen Satrawala and Raj K. Joshi
Organics 2023, 4(2), 251-264; https://doi.org/10.3390/org4020020 - 25 May 2023
Cited by 2 | Viewed by 2094
Abstract
In this report, the catalytic potential of chalcogen-stabilized iron carbonyl clusters [Fe3E2(CO)9 (E = S, Se, Te)] for the photolytic hydration of alkynes has been explored. The iron chalcogenide clusters bring excellent transformations of terminal and internal alkynes [...] Read more.
In this report, the catalytic potential of chalcogen-stabilized iron carbonyl clusters [Fe3E2(CO)9 (E = S, Se, Te)] for the photolytic hydration of alkynes has been explored. The iron chalcogenide clusters bring excellent transformations of terminal and internal alkynes to their respective keto products in just 25 min photolysis at −5 °C in inert free and aqueous conditions. After the completion of the reaction, the product can be extracted from organic solvent, and due to the lower solubility of the catalyst in water, it can also be isolated and further reused several times prior to any activation. The catalyst was also found to be active in thermal conditions and bring about the desired transformations with average to good catalytic efficiency. Moreover, during the thermal reaction, the catalyst decomposed and formed the nanoparticles of iron selenides, which worked as a single-source precursor for FeSe nanomaterials. The presented photolysis methodology was found to be most feasible, economical, instantly produce the desired product, and work for a wide range of internal and terminal alkynes; hence, all these features made this method superior to the other reported ones. This report also serves as the first catalytic report of chalcogen-stabilized iron carbonyl clusters for alkyne hydrations. Full article
(This article belongs to the Collection Advanced Research Papers in Organics)
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19 pages, 6801 KiB  
Review
Synthetic Organic Molecules as Metallic Corrosion Inhibitors: General Aspects and Trends
by Renato Corrêa da Silva Lessa
Organics 2023, 4(2), 232-250; https://doi.org/10.3390/org4020019 - 17 May 2023
Cited by 2 | Viewed by 2402
Abstract
Organic molecules are gaining special attention over the last years in the corrosion area thanks to their general low achievable cytotoxicity, structural versatility, and environmentally friendly obtainment methods. Under those approaches, synthetic organic motifs have attracted the interest of researchers due to their [...] Read more.
Organic molecules are gaining special attention over the last years in the corrosion area thanks to their general low achievable cytotoxicity, structural versatility, and environmentally friendly obtainment methods. Under those approaches, synthetic organic motifs have attracted the interest of researchers due to their variated methods of obtention through molecular manipulation via diverse chemical reactions, allowing the production of adequately planned structures or repurposing their original application in the case of drugs. This review summarizes general aspects that are desired in organic molecules as corrosion inhibitors, presenting selected works published in the 2022–2023 period and emphasizing the importance of finding novel and different organic corrosion inhibitors. Patents were not considered in this review. Scifinder, Google Scholar, and Web of Science were employed as databases. Mathematical and analytical methods involved in the search for corrosion inhibitors are out of this review’s scope. Full article
(This article belongs to the Collection Advanced Research Papers in Organics)
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13 pages, 3227 KiB  
Article
A Novel Class of Functionally Tuneable Star-Shaped Molecules for Interaction with Multiple Proteins
by Debashis Barik, Geethanjali Anand, Subba Rao Cheekatla and Mintu Porel
Organics 2023, 4(2), 219-231; https://doi.org/10.3390/org4020018 - 16 May 2023
Viewed by 1530
Abstract
Molecules with tuneable properties are well known for their applications in the material and bio-medical fields; nevertheless, the structural and functional tunability makes them more significant in diverse applications. Herein, we designed and synthesized a novel class of star-shaped molecules via incorporating two [...] Read more.
Molecules with tuneable properties are well known for their applications in the material and bio-medical fields; nevertheless, the structural and functional tunability makes them more significant in diverse applications. Herein, we designed and synthesized a novel class of star-shaped molecules via incorporating two important functional groups, i.e., triazole and dithiocarbamate (DTC). The rationale behind selecting these two key functional groups is their diverse applications, e.g., DTC having applications for therapeutics, pesticides, and vulcanizing agents, and triazole having applications for anti-cancer, fungicides, anti-microbials, inhibitors, etc. The structure of the molecules was strategically designed in such a way that their overall structures are the same (central tertiary-amine and peripheral hydroxy groups), except the key functional group (DTC and triazole) in the respective molecules was different. Following synthesis and characterization, the influence of DTC and triazole groups on their bioactivity was compared via interacting with the most abundant proteins present in the blood, including serum albumin, trypsin, haemoglobin, and ribonuclease. From both the experimental and molecular docking studies, it was confirmed that the triazole molecule has a higher binding affinity towards these proteins as compared to the DTC molecule. In summary, two star-shaped DTC- and triazole-based molecules were synthesized and their bioactivity was compared via binding with blood plasma proteins. Full article
(This article belongs to the Collection Advanced Research Papers in Organics)
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13 pages, 1862 KiB  
Article
The Regio- and Stereoselective Synthesis of 1,4-Diarylbut-1-en-3-ynes Having Aryl Groups at the Mutual Syn Positions
by Szymon Rogalski, Natalia Szymaszek and Cezary Pietraszuk
Organics 2023, 4(2), 206-218; https://doi.org/10.3390/org4020017 - 8 May 2023
Viewed by 1190
Abstract
(E)-1-aryl-2,4-bis(trimethylsilyl)but-1-en-3-ynes readily undergo protodesilylation and subsequent aerobic, copper-free Sonogashira cross-coupling with aryl halides to form (E)-1,4-diaryl-2-(trimethylsilyl)but-1-en-3-ynes. The proposed one-pot, two-step approach allows access to the isomers containing aryl substituents in mutual syn positions. The resulting 2-silyl enynes can be further converted by proto- [...] Read more.
(E)-1-aryl-2,4-bis(trimethylsilyl)but-1-en-3-ynes readily undergo protodesilylation and subsequent aerobic, copper-free Sonogashira cross-coupling with aryl halides to form (E)-1,4-diaryl-2-(trimethylsilyl)but-1-en-3-ynes. The proposed one-pot, two-step approach allows access to the isomers containing aryl substituents in mutual syn positions. The resulting 2-silyl enynes can be further converted by proto- or halodesilylation. Full article
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10 pages, 1530 KiB  
Article
Computational Modeling of the Feasibility of Substituted [1.1.1]Propellane Formation from Anionic Bridgehead Bromide Precursors
by Katherine E. Gates, Caitlin Herring, Andrew T. Lumpkin, Robert J. Maraski, Elizabeth G. Perry, Madelen G. Prado, Sarah L. Quigley, Jazmine V. Ridlehoover, Edith Salazar, Kynslei Sims, Kaitlin R. Stephenson, Emma A. Stewart, Mackenzie E. Sullivan, James R. Tucker and Gary W. Breton
Organics 2023, 4(2), 196-205; https://doi.org/10.3390/org4020016 - 4 May 2023
Cited by 1 | Viewed by 1309
Abstract
[1.1.1]Propellane, a compound whose structure includes two saturated carbons in which all four bonds are directed into a single hemisphere, is of theoretical interest, but has also seen recent practical applications. Mono-, di-, and trisubstituted derivatives of this propellane (by substitution of its [...] Read more.
[1.1.1]Propellane, a compound whose structure includes two saturated carbons in which all four bonds are directed into a single hemisphere, is of theoretical interest, but has also seen recent practical applications. Mono-, di-, and trisubstituted derivatives of this propellane (by substitution of its CH2 bridges with O, S, NH, CF2, CO, SO, and SO2) remain unknown despite several computational studies that have suggested some may be stable. In this study, we show that, in several cases, substituted propellanes are spontaneously formed upon the attempted computational optimization of the geometries of anionic bridgehead bromide precursors using the ωB97X-D/aug-cc-pVDZ DFT method. Spontaneous formation suggests that these propellanes are at lower energy relative to the precursors and, therefore, are promising synthetic targets. The success or failure to spontaneously form the propellane is considered in relation to the length and strain energy of the central bridgehead-bridgehead bond, as well as the total strain energy of each propellane. Full article
(This article belongs to the Collection Advanced Research Papers in Organics)
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10 pages, 3342 KiB  
Communication
A Reaction of N-Substituted Succinimides with Hydroxylamine as a Novel Approach to the Synthesis of Hydroxamic Acids
by Bogdan A. Tretyakov, Svyatoslav Y. Gadomsky and Alexei A. Terentiev
Organics 2023, 4(2), 186-195; https://doi.org/10.3390/org4020015 - 27 Apr 2023
Cited by 1 | Viewed by 2636
Abstract
We describe a novel two-step approach for the synthesis of compounds with a hydroxyl-amide group (hydroxamic acids), which are widely known for their biological activity (histone deacetylase inhibitors, matrix metalloproteinases inhibitors and others). The first stage is the synthesis of N-substituted succinimide [...] Read more.
We describe a novel two-step approach for the synthesis of compounds with a hydroxyl-amide group (hydroxamic acids), which are widely known for their biological activity (histone deacetylase inhibitors, matrix metalloproteinases inhibitors and others). The first stage is the synthesis of N-substituted succinimide via the reaction of aromatic amine or carboxylic acid hydrazide with succinic anhydride. The second step involves the imide ring opening reaction by hydroxylamine. For both stages, universal synthetic methods are developed to exclude additional purification procedures for the target compounds. Sixteen hydroxamic acids are synthesized using the developed approach. Most of the compounds are obtained for the first time. Full article
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13 pages, 6299 KiB  
Review
Advance in the Synthesis of Sulfoxides and Sulfinamides from β-Sulfinyl Esters
by Xianjie Yin, Qiaoling Zhang and Qingle Zeng
Organics 2023, 4(2), 173-185; https://doi.org/10.3390/org4020014 - 19 Apr 2023
Cited by 2 | Viewed by 1474
Abstract
Sulfoxides and sulfinamides play important roles in the pharmaceutical industry, organic synthesis and fine chemicals. This review will demonstrate that, under catalysis by transition metals, β-sulfinyl esters, as nucleophilic reagents, react with a variety of electrophilic reagents to produce sulfoxides and sulfinamides. [...] Read more.
Sulfoxides and sulfinamides play important roles in the pharmaceutical industry, organic synthesis and fine chemicals. This review will demonstrate that, under catalysis by transition metals, β-sulfinyl esters, as nucleophilic reagents, react with a variety of electrophilic reagents to produce sulfoxides and sulfinamides. The important prospect of the asymmetric catalytic synthesis of chiral sulfur-containing molecules in this field is described. Full article
(This article belongs to the Collection Advanced Research Papers in Organics)
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9 pages, 1162 KiB  
Article
Reinvestigation of the Room Temperature Photochemical Reaction between N-Methyl-1,2,4-triazoline-3,5-dione (MeTAD) and Benzene
by Gary W. Breton
Organics 2023, 4(2), 164-172; https://doi.org/10.3390/org4020013 - 17 Apr 2023
Viewed by 1166
Abstract
The photochemical reaction of N-methyl-1,2,4-triazoline-3,5-dione (MeTAD) with benzene is known to lead to a Diels–Alder cycloaddition product when conducted at low temperatures (i.e., <−60 °C). This reactivity has been exploited recently for novel synthetic applications. It was previously reported that no reaction [...] Read more.
The photochemical reaction of N-methyl-1,2,4-triazoline-3,5-dione (MeTAD) with benzene is known to lead to a Diels–Alder cycloaddition product when conducted at low temperatures (i.e., <−60 °C). This reactivity has been exploited recently for novel synthetic applications. It was previously reported that no reaction between MeTAD and benzene occurs at room temperature. However, it has now been discovered that MeTAD reacts effectively with benzene upon visible light irradiation over a several day period at room temperature. The major product is a para-substituted bisurazole adduct. Our studies indicate that the adduct is formed via sequential aromatic substitution reactions made possible by electron transfer from the aromatic ring to the highly electrophilic triplet state of photoactivated MeTAD. Full article
(This article belongs to the Special Issue Chemistry of Heterocycles)
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18 pages, 7770 KiB  
Article
Exploration of the Divergent Outcomes for the Nenitzescu Reaction of Piperazinone Enaminoesters
by Rebecca Hermans, Max Van Hoof, Luc Van Meervelt and Wim Dehaen
Organics 2023, 4(2), 146-163; https://doi.org/10.3390/org4020012 - 7 Apr 2023
Viewed by 1616
Abstract
The Nenitzescu reaction is a condensation reaction between an enamine and a quinone, which can give rise to a wide variety of reaction products depending on the nature of the starting material and the reaction conditions. The most commonly observed products are 5-hydroxyindoles [...] Read more.
The Nenitzescu reaction is a condensation reaction between an enamine and a quinone, which can give rise to a wide variety of reaction products depending on the nature of the starting material and the reaction conditions. The most commonly observed products are 5-hydroxyindoles and 5-hydroxybenzofurans. Both classes are of interest since they are known to possess a variety of promising bioactivities. Despite the high chemodivergency for this reaction, it remains an interesting synthetic strategy thanks to the mild reaction conditions, easily accessible starting materials and simple reaction procedures. For these reasons, our research group investigated the Nenitzescu reaction of piperazinone enaminoesters, resulting in the unexpected formation of rearranged 2-imidazolidinone benzofurans. In this work, we aimed to develop reaction conditions that favor the formation of 5-hydroxyindoles via an extensive, multivariate optimization study. This led to valuable insights into the parameters that influence regio- and chemoselectivity. Furthermore, two novel products were obtained, a pyrrolo[2,3-f]indole and a benzofuranone, both of which are rarely reported in the literature. Full article
(This article belongs to the Special Issue Chemistry of Heterocycles)
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9 pages, 3225 KiB  
Communication
A New Rapid and Specific Iodination Reagent for Phenolic Compounds
by Till Hauenschild and Dariush Hinderberger
Organics 2023, 4(2), 137-145; https://doi.org/10.3390/org4020011 - 4 Apr 2023
Viewed by 1499
Abstract
A new rapid iodination reagent, N1,N3,N5-tris[(2,4,6-trimethylpyridine)iodo(I)]-2,4,6-triphenyl-s-triazine trihexafluorophosphate, was synthesized in a modification of the established synthesis of 2,4,6-triiodo-3,5-dimethylphenol in the presence of bis(2,4,6-trimethylpyridine)iodo(I) hexafluorophosphate and used for the precise post-modification of mono- and trisubstituted [...] Read more.
A new rapid iodination reagent, N1,N3,N5-tris[(2,4,6-trimethylpyridine)iodo(I)]-2,4,6-triphenyl-s-triazine trihexafluorophosphate, was synthesized in a modification of the established synthesis of 2,4,6-triiodo-3,5-dimethylphenol in the presence of bis(2,4,6-trimethylpyridine)iodo(I) hexafluorophosphate and used for the precise post-modification of mono- and trisubstituted phenyl compounds. We performed triple iodinations with our new phenyl-based compounds as a proof of principle of selected types of phenols, ß-sympatholytic agents and their spin-labeled derivatives, which can be employed in electron paramagnetic resonance (EPR) spectroscopy. The new rapid iodination reagent can be employed with high reactivity and regioselectivity. Full article
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