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Organics, Volume 3, Issue 4 (December 2022) – 11 articles

Cover Story (view full-size image): In addition to their iconic structure, fullerenes display very interesting chemistry. They readily undergo Diels-Alder (DA) reactions with dienes, allowing for facile functionalization. We analyze the impact of isomerism, aromaticity and solvation on the energies of the DA reaction between fullerenes (C60, C70 and IC60MA) and anthracene. The identity of the fullerene has negligible effect on the energy of reaction. Yet, while C70 shows high regioselectivity towards the edge of the molecule, several isomers of the IC60MA-athracene adduct have similar stability. Solvation and thermal energy have small impact on regioselectivity, but both factors reduce the exothermicity of the DA reaction. HOMA analysis indicate an increased aromaticity in the fullerene hexagons adjacent to the addend and DFT calculations highlight the importance of dispersive interactions at the surface of the fullerene. View this paper
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14 pages, 2928 KiB  
Communication
Neighboring Nitrogen Atom-Induced Reactions of Azidoacetyl Hydrazides, including Unexpected Nitrogen-Nitrogen Bond Cleavage of the Hydrazide
by Hiroki Tanimoto, Ryo Adachi, Aoi Otsuki and Takenori Tomohiro
Organics 2022, 3(4), 520-533; https://doi.org/10.3390/org3040035 - 19 Dec 2022
Viewed by 2375
Abstract
We studied the hydrazide compounds of the α-azidoacetyl group, which showed specific click reactivity by the intramolecular hydrogen bonding between the azido group and the N-H of the hydrazide moiety. In the competitive click reactions with a general alkyl azide, both traceless and [...] Read more.
We studied the hydrazide compounds of the α-azidoacetyl group, which showed specific click reactivity by the intramolecular hydrogen bonding between the azido group and the N-H of the hydrazide moiety. In the competitive click reactions with a general alkyl azide, both traceless and non-traceless Staudinger-Bertozzi ligation occurred azide-site-selectively by the acceleration effect of the hydrogen bonding. However, the product obtained from the traceless reaction was further transformed into heterocyclic compounds. In addition, in an attempt at a synthesis of naphthalimide-possessing azidoacetyl hydrazide, nitrogen-nitrogen bond cleavage of the azidoacetyl hydrazides occurred to give the reduced amine product. These unexpected results could help design molecules for the successful Staudinger-Bertozzi ligation of the hydrazide compounds and develop a new nitrogen-nitrogen bond cleavage method. Full article
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13 pages, 2377 KiB  
Article
Bis(3-methylthio-1-azulenyl)phenylmethyl Cations and Dications Connected by a 1,4-Phenylene Spacer: Synthesis and Their Electrochemical Properties
by Taku Shoji, Naoko Sakata, Ryuta Sekiguchi and Shunji Ito
Organics 2022, 3(4), 507-519; https://doi.org/10.3390/org3040034 - 16 Dec 2022
Viewed by 1387
Abstract
The preparation of bis(3-methylthio-1-azulenyl)phenylmethyl cations and 1,4-phenylenebis[bis(3,6-di-tert-butyl-1-azulenyl)methyl] dications was accomplished by the hydride abstraction of the corresponding hydride derivatives, which were synthesized by the acid-catalyzed condensation of 1-azulenyl methyl sulfide with benzaldehyde and terephthalaldehyde with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. The intramolecular charge transfer among [...] Read more.
The preparation of bis(3-methylthio-1-azulenyl)phenylmethyl cations and 1,4-phenylenebis[bis(3,6-di-tert-butyl-1-azulenyl)methyl] dications was accomplished by the hydride abstraction of the corresponding hydride derivatives, which were synthesized by the acid-catalyzed condensation of 1-azulenyl methyl sulfide with benzaldehyde and terephthalaldehyde with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. The intramolecular charge transfer among the azulene ring and the methylium moieties of these cations and dications was investigated by UV–Vis spectroscopy and electrochemical analyses. The pKR+ values of the cations were examined for their thermodynamic stability spectrophotometrically. The voltammetry experiments of these cations revealed their reversible reduction waves on their cyclic voltammograms. Moreover, a notable spectral change of cations was observed by spectroelectrochemistry during electrochemical reduction conditions. Full article
(This article belongs to the Collection Advanced Research Papers in Organics)
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5 pages, 518 KiB  
Communication
Efficient Synthesis of a 2-Decyl-tetradecyl Substituted 7-Bromophenothiazine-3-carbaldehyde Building Block for Functional Dyes
by Burak Kürsat Börüsah and Thomas J. J. Müller
Organics 2022, 3(4), 502-506; https://doi.org/10.3390/org3040033 - 7 Dec 2022
Cited by 3 | Viewed by 1356
Abstract
(1) Polyfunctional molecules are versatile building blocks for efficient syntheses of novel phenothiazine-based materials with promising electronic properties. A prerequisite is a facile, high yielding access to these building blocks that bear solubilizing moieties and functional groups for orthogonal transformation. (2) Here, an [...] Read more.
(1) Polyfunctional molecules are versatile building blocks for efficient syntheses of novel phenothiazine-based materials with promising electronic properties. A prerequisite is a facile, high yielding access to these building blocks that bear solubilizing moieties and functional groups for orthogonal transformation. (2) Here, an efficient, improved two-step protocol for accessing a solubilizing 2-decyl-tetradecyl functionalized phenothiazine, i.e., an N-alkylated 7-bromophenothiazine-3-carbaldehyde, by Vilsmeier–Haack formylation and NBS (N-bromo succinimide) bromination is reported. (3) The sequence proceeds with higher yields and in shorter reaction times than the standard access employing bromination with elementary bromine. In addition, the work-up procedure essentially uses absorptive filtration on a plug of silica with the eluent. Full article
(This article belongs to the Special Issue Aromatic Heterocycles: A Wonderful Pool of Organic Materials)
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11 pages, 2242 KiB  
Article
Phosphonated Polyethylenimine Maghemite Nanoparticles: A Convenient Support of Palladium for Cross-Coupling Reactions
by Clément Monteil, Etienne Jean, Nathalie Bar and Didier Villemin
Organics 2022, 3(4), 491-501; https://doi.org/10.3390/org3040032 - 21 Nov 2022
Cited by 1 | Viewed by 1428
Abstract
Phosphonated polyethylenimine grafted on iron oxide nanoparticles was used as a magnetic support for loading palladium. This cheap and accessible heterogeneous catalyst demonstrated good efficiency in Suzuki-Miyaura, Mizoroki-Heck, and Tsuji-Trost couplings. The nanocomposite is resistant to harsh conditions and can therefore be recycled [...] Read more.
Phosphonated polyethylenimine grafted on iron oxide nanoparticles was used as a magnetic support for loading palladium. This cheap and accessible heterogeneous catalyst demonstrated good efficiency in Suzuki-Miyaura, Mizoroki-Heck, and Tsuji-Trost couplings. The nanocomposite is resistant to harsh conditions and can therefore be recycled up to 10 cycles with high catalyst efficiency. Full article
(This article belongs to the Collection Advanced Research Papers in Organics)
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10 pages, 1899 KiB  
Article
Synthesis of 3-Hydroxy-9H-fluorene-2-carboxylates via Michael Reaction, Robinson Annulation, and Aromatization
by Yu-Min Wang, Yi-Hung Liu and Shiuh-Tzung Liu
Organics 2022, 3(4), 481-490; https://doi.org/10.3390/org3040031 - 10 Nov 2022
Viewed by 1892
Abstract
A series of 3-hydroxy-fluorene-2-carboxylate compounds were prepared from Michael addition of acetoacetate to 2-benzylideneindan-l-one followed by Robinson annulation and aromatization. In this reaction, we were able to isolate two Robinson annulation products and characterize them. This sequential reaction could proceed without the isolation [...] Read more.
A series of 3-hydroxy-fluorene-2-carboxylate compounds were prepared from Michael addition of acetoacetate to 2-benzylideneindan-l-one followed by Robinson annulation and aromatization. In this reaction, we were able to isolate two Robinson annulation products and characterize them. This sequential reaction could proceed without the isolation of intermediates to give the desired products directly in reasonable yields. Full article
(This article belongs to the Collection Advanced Research Papers in Organics)
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11 pages, 1564 KiB  
Article
How Do Positions of Phosphito Units on a Calix[4]Arene Platform Affect the Enantioselectivity of a Catalytic Reaction?
by Shaima Hkiri and David Sémeril
Organics 2022, 3(4), 470-480; https://doi.org/10.3390/org3040030 - 9 Nov 2022
Cited by 1 | Viewed by 1403
Abstract
Three chiral diphosphites, (S,S)-5,17-bis(1,1′-binaphthyl-2,2′-dioxyphosphanyloxy)-25,26,27,28-tetrapropyloxycalix[4]arene (1), (S,S)-5,11,17,23-tetra-tert-butyl-25,27-dipropoxy-26,28-bis(1,1′-binaphthyl-2,2′-dioxyphosphanyloxy)calix[4]arene (2) and (S,S)-5,11,17,23-tetra-tert-butyl-25,26-dipropoxy-27,28-bis(1,1′-binaphthyl-2,2′-dioxyphosphanyloxy)calix[4]arene (3), based on conical calix[4]arene were investigated in the rhodium-catalyzed asymmetric hydrogenation [...] Read more.
Three chiral diphosphites, (S,S)-5,17-bis(1,1′-binaphthyl-2,2′-dioxyphosphanyloxy)-25,26,27,28-tetrapropyloxycalix[4]arene (1), (S,S)-5,11,17,23-tetra-tert-butyl-25,27-dipropoxy-26,28-bis(1,1′-binaphthyl-2,2′-dioxyphosphanyloxy)calix[4]arene (2) and (S,S)-5,11,17,23-tetra-tert-butyl-25,26-dipropoxy-27,28-bis(1,1′-binaphthyl-2,2′-dioxyphosphanyloxy)calix[4]arene (3), based on conical calix[4]arene were investigated in the rhodium-catalyzed asymmetric hydrogenation of α-dehydroamino esters. High conversions were observed after 24 h under 5 bar of hydrogen whatever the employed diphosphite, and the chiral induction increases in the order 1 < 3 < 2. This may be due to the presence of the calix[4]arene moiety, which by its presence modifies the second coordination sphere of the catalytic center. The larger steric hindrance around the rhodium atom leads to the higher enantiomeric excess. Full article
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24 pages, 5791 KiB  
Review
Thienothiophene Scaffolds as Building Blocks for (Opto)Electronics
by Jan Podlesný and Filip Bureš
Organics 2022, 3(4), 446-469; https://doi.org/10.3390/org3040029 - 3 Nov 2022
Cited by 3 | Viewed by 1873
Abstract
Thieno[3,2-b]thiophene and isomeric thieno[2,3-b]thiophene represent fused, bicyclic and electron rich heterocycles. These small planar organic compounds belong to the remarkable family of annulated building blocks for various organic materials. The first part of this review focuses on the synthesis [...] Read more.
Thieno[3,2-b]thiophene and isomeric thieno[2,3-b]thiophene represent fused, bicyclic and electron rich heterocycles. These small planar organic compounds belong to the remarkable family of annulated building blocks for various organic materials. The first part of this review focuses on the synthesis of the primary unsubstituted thienothiophene scaffolds. All synthetic pathways available in the literature, dating from the 19th century, are summarized. The second part is devoted to the applications of the thienothiophene-derived materials across (opto)electronics. Organic light emitting diodes, organic solar cells, organic field-effect transistors and nonlinear optics were identified as the most successful application areas of both thienothiophenes. The fundamental structure-property relationships were evaluated for each particular group of derivatives. Full article
(This article belongs to the Special Issue Aromatic Heterocycles: A Wonderful Pool of Organic Materials)
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16 pages, 6899 KiB  
Review
Synthetic Pathways to Pyrido[3,4-c]pyridazines and Their Polycyclic Derivatives
by Temitayo Omowumi Alegbejo Price, Flavio da Silva Emery and Wim Dehaen
Organics 2022, 3(4), 430-445; https://doi.org/10.3390/org3040028 - 18 Oct 2022
Viewed by 1946
Abstract
Pyrido[3,4-c]pyridazines are nitrogen-containing scaffolds that have been described as being promising in medicinal chemistry, but they are rather rare chemicals. In this review article, the literature on synthetic pathways towards pyrido[3,4-c]pyridazines is listed exhaustively, first with the bicyclic systems [...] Read more.
Pyrido[3,4-c]pyridazines are nitrogen-containing scaffolds that have been described as being promising in medicinal chemistry, but they are rather rare chemicals. In this review article, the literature on synthetic pathways towards pyrido[3,4-c]pyridazines is listed exhaustively, first with the bicyclic systems themselves that are obtained starting either from pyridines, pyridazines or other heterocycles. Then, the reports on the related tricyclic derivatives are discussed, again according to the source heterocycle, and finally we mention some examples on polycyclic systems. Full article
(This article belongs to the Collection Advanced Research Papers in Organics)
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15 pages, 6430 KiB  
Article
Design, Synthesis, and Photo-Responsive Properties of a Collagen Model Peptide Bearing an Azobenzene
by Daisuke Sato, Hitomi Goto, Yui Ishizaki, Tetsuya Narimatsu and Tamaki Kato
Organics 2022, 3(4), 415-429; https://doi.org/10.3390/org3040027 - 11 Oct 2022
Viewed by 1511
Abstract
Collagen is a vital component of the extracellular matrix in animals. Collagen forms a characteristic triple helical structure and plays a key role in supporting connective tissues and cell adhesion. The ability to control the collagen triple helix structure is useful for medical [...] Read more.
Collagen is a vital component of the extracellular matrix in animals. Collagen forms a characteristic triple helical structure and plays a key role in supporting connective tissues and cell adhesion. The ability to control the collagen triple helix structure is useful for medical and conformational studies because the physicochemical properties of the collagen rely on its conformation. Although some photo-controllable collagen model peptides (CMPs) have been reported, satisfactory photo-control has not yet been achieved. To achieve this objective, detailed investigation of the isomerization behavior of the azobenzene moiety in CMPs is required. Herein, two CMPs were attached via an azobenzene linker to control collagen triple helix formation by light irradiation. Azo-(PPG)10 with two (Pro-Pro-Gly)10 CMPs linked via a photo-responsive azobenzene moiety was designed and synthesized. Conformational changes were evaluated by circular dichroism and the cis-to-trans isomerization rate calculated from the absorption of the azobenzene moiety indicated that the collagen triple helix structure was partially disrupted by isomerization of the internal azobenzene. Full article
(This article belongs to the Collection Advanced Research Papers in Organics)
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35 pages, 8646 KiB  
Review
Ten Years Milestones in Xanthine Oxidase Inhibitors Discovery: Febuxostat-Based Inhibitors Trends, Bifunctional Derivatives, and Automatized Screening Assays
by Miguel F. S. de Abreu, Camila A. Wegermann, Millena S. Ceroullo, Isabella G. M. Sant’Anna and Renato C. S. Lessa
Organics 2022, 3(4), 380-414; https://doi.org/10.3390/org3040026 - 10 Oct 2022
Cited by 2 | Viewed by 2453
Abstract
Xanthine oxidase (XO) is an enzyme involved in the oxidative process of hypoxanthine and xanthine to uric acid (UA). This process also produces reactive oxygen species (ROS) as byproducts. Both UA and ROS are dangerous for human health, and some health conditions trigger [...] Read more.
Xanthine oxidase (XO) is an enzyme involved in the oxidative process of hypoxanthine and xanthine to uric acid (UA). This process also produces reactive oxygen species (ROS) as byproducts. Both UA and ROS are dangerous for human health, and some health conditions trigger upregulation of XO activity, which results in many diseases (cancer, atherosclerosis, hepatitis, gout, and others) given the worsened scenario of ROS and UA overproduction. So, XO became an attractive target to produce and discover novel selective drugs based on febuxostat, the most recent XO inhibitor out of only two approved by FDA. Under this context, high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) have been successfully applied to rapidly and easily screen for bioactive compounds, isolated or in complex natural matrixes, that act as enzyme inhibitors through the use of an immobilized enzyme reactor (IMER). This article’s goal is to present advances comprising febuxostat-based XO inhibitors as a new trend, bifunctional moieties capable of inhibiting XO and modulating ROS activity, and in-flow techniques employing an IMER in HPLC and CE to screen for synthetic and natural compounds that act as XO inhibitors. Full article
(This article belongs to the Collection Advanced Research Papers in Organics)
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16 pages, 2020 KiB  
Article
Theoretical Study on the Diels–Alder Reaction of Fullerenes: Analysis of Isomerism, Aromaticity, and Solvation
by Diogo J. L. Rodrigues, Luís M. N. B. F. Santos, André Melo and Carlos F. R. A. C. Lima
Organics 2022, 3(4), 364-379; https://doi.org/10.3390/org3040025 - 22 Sep 2022
Cited by 2 | Viewed by 2058
Abstract
Fullerenes are reactive as dienophiles in Diels–Alder reactions. Their distinctive molecular shape and properties result in interesting and sometimes elusive reaction patterns. Herein, to contribute to the understanding of fullerene reactivity, we evaluate the energies of reactions for Diels–Alder cycloadditions of C60 [...] Read more.
Fullerenes are reactive as dienophiles in Diels–Alder reactions. Their distinctive molecular shape and properties result in interesting and sometimes elusive reaction patterns. Herein, to contribute to the understanding of fullerene reactivity, we evaluate the energies of reactions for Diels–Alder cycloadditions of C60, C70, and IC60MA with anthracene (Ant), by means of DFT computational analysis in vacuum and solution. The methods used showed little differentiation between the reactivity of the different fullerenes. The C70-Ant adducts where addition takes place near the edge of the fullerene were found to be the most stable regioisomers. For the IC60MA-Ant adducts, the calculated energies of reaction increase in the order: equatorial > trans-3 > trans-2 ≈ trans-4 ≈ trans-1 > cis-3 > cis-2. The change in the functional suggests the existence of stabilizing dispersive interactions between the surface of the fullerene and the addends. HOMA (harmonic oscillator model of aromaticity) analysis indicated an increase in aromaticity in the fullerene hexagons adjacent to the bonded addend. This increase is bigger in the rings of bisadduct isomers that are simultaneously adjacent to both addends, which helps explain the extra stability of the equatorial isomers. Solvation by m-xylene decreases the exothermicity of the reactions studied but has little distinguishing effect on the possible isomers. Thermal corrections reduce the exothermicity of the reactions by ~10 kJ∙mol−1. Full article
(This article belongs to the Collection Advanced Research Papers in Organics)
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