Special Issue "Heteroatom Rich Organic Heterocycles"

A special issue of Molbank (ISSN 1422-8599). This special issue belongs to the section "Organic Synthesis".

Deadline for manuscript submissions: 30 September 2021.

Special Issue Editors

Prof. Dr. Panayiotis A. Koutentis
E-Mail Website
Guest Editor
Department of Chemistry, University of Cyprus, P. O. Box 20537, 1678 Nicosia, Cyprus
Interests: heterocyclic chemistry; sulfur-nitrogen heterocycles; synthetic methods; azaacenes; zwitterionic acenes; stable organic radicals; biologically active heterocycles; isothiazoles; 1,2,3-dithiazoles; 1,2,6-thiadiazines;1,2,4-benzotriazines
Special Issues and Collections in MDPI journals
Dr. Andreas S. Kalogirou
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Guest Editor
Department of Life Sciences, School of Sciences, European University Cyprus, 6 Diogenis Str., Engomi, P.O. Box 22006, 1516 Nicosia, Cyprus
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

The International Union of Pure and Applied Chemistry (IUPAC) definition of a heterocycle requires a cyclic compound to contain at least two different elements as members of its ring(s). From the perspective of organic heterocycles, one of these elements must be carbon while the other is typically nitrogen, oxygen or sulfur. Common organic heterocycles contain either one or two heteroatoms, and many of these compounds have important commercial applications, as well as being important for many biological processes.

Less common heterocycles are those that contain either many heteroatoms, or a greater variety of heteroatoms. Increasing the atomic weight of the heteroatom also leads to less well known and less studied heterocycles. These heteroatom rich and often more complex heterocycles constitute an underexplored and underexploited area in the chemical sciences. The constant effort being made to increase structural diversity and to find new privileged structures in the biological and materials sciences can, therefore, only benefit from increased efforts to explore the area of rare heterocycles. This Special Issue encourages authors to report new developments in all aspects of heteroatom rich organic heterocycles, irrespective of ring size, that contain at least two different elements other than carbon and at least three heteroatoms within the heterocycles ring system.

Prof. Dr. Panayiotis A. Koutentis
Dr. Andreas S. Kalogirou
Guest Editors

Manuscript Submission Information

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Keywords

  • Heterocyclic Chemistry
  • Aromatic Heterocycles
  • Non-aromatic Heterocycles
  • Fused Heterocycles
  • Nitrogen
  • Oxygen
  • Sulfur
  • Selenium
  • Tin
  • Boron
  • Phosphorus
  • Silicon

Published Papers (14 papers)

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Research

Short Note
7-Bromo-[1,2,5]selenadiazolo[3,4-d]pyridazin-4(5H)-one
Molbank 2021, 2021(2), M1229; https://doi.org/10.3390/M1229 - 05 Jun 2021
Viewed by 286
Abstract
New heterocyclic systems containing 1,2,5-chalcogenadiazoles are of great interest for the creation of organic photovoltaic materials and biologically active compounds. In this communication, 3,6-dibromopyridazine-4,5-diamine was investigated in reaction with selenium dioxide in order to obtain 4,7-dibromo-[1,2,5]selenadiazolo[3,4-d]pyridazine. We found that 7-bromo-[1,2,5]selenadiazolo[3,4-d [...] Read more.
New heterocyclic systems containing 1,2,5-chalcogenadiazoles are of great interest for the creation of organic photovoltaic materials and biologically active compounds. In this communication, 3,6-dibromopyridazine-4,5-diamine was investigated in reaction with selenium dioxide in order to obtain 4,7-dibromo-[1,2,5]selenadiazolo[3,4-d]pyridazine. We found that 7-bromo-[1,2,5]selenadiazolo[3,4-d]pyridazin-4(5H)-one, the first representative of the new heterocyclic system, was isolated as a hydrolysis product of the corresponding 4,7-dibromoderivative. The structure of the newly synthesized compound was established by means of elemental analysis, high-resolution mass spectrometry, 1H, 13C NMR, IR and UV spectroscopy, and mass spectrometry. Full article
(This article belongs to the Special Issue Heteroatom Rich Organic Heterocycles)
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Scheme 1

Short Note
Methyl 2-Amino-4-[1-(tert-butoxycarbonyl)azetidin-3-yl]-1,3-selenazole-5-carboxylate
Molbank 2021, 2021(2), M1207; https://doi.org/10.3390/M1207 - 01 May 2021
Viewed by 408
Abstract
Methyl 2-amino-4-[1-(tert-butoxycarbonyl)azetidin-3-yl]-1,3-selenazole-5-carboxylate as a newly functionalized heterocyclic amino acid was obtained via [3+2] cycloaddition. The structure of the novel 1,3-selenazole was unequivocally confirmed by detailed 1H, 13C, 15N, and 77Se NMR spectroscopic experiments, HRMS and elemental analysis. Full article
(This article belongs to the Special Issue Heteroatom Rich Organic Heterocycles)
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Figure 1

Short Note
4-(7-Bromobenzo[d][1,2,3]thiadiazol-4-yl)morpholine
Molbank 2021, 2021(2), M1202; https://doi.org/10.3390/M1202 - 13 Apr 2021
Viewed by 515
Abstract
Dibromoderivatives of benzofused chalcogen-nitrogen heterocycles are important precursors in the synthesis of various photovoltaic materials. 4,7-Dibromobenzo[d][1,2,3]thiadiazole is a practically unexplored compound in this series. In this communication, it was shown that the nucleophilic substitution of 4,7-dibromobenzo[d][1,2,3]thiadiazole with morpholine gave [...] Read more.
Dibromoderivatives of benzofused chalcogen-nitrogen heterocycles are important precursors in the synthesis of various photovoltaic materials. 4,7-Dibromobenzo[d][1,2,3]thiadiazole is a practically unexplored compound in this series. In this communication, it was shown that the nucleophilic substitution of 4,7-dibromobenzo[d][1,2,3]thiadiazole with morpholine gave selectively 4-substituted product—4-(7-bromobenzo[d][1,2,3]thiadiazol-4-yl)morpholine. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR, and IR spectroscopy, mass-spectrometry, and X-ray analysis. Full article
(This article belongs to the Special Issue Heteroatom Rich Organic Heterocycles)
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Figure 1

Short Note
5,5′-Thiobis(3-methoxy-4H-1,2,6-thiadiazin-4-one)
Molbank 2019, 2019(2), M1064; https://doi.org/10.3390/M1064 - 09 Jun 2019
Viewed by 564
Abstract
The reaction of 3-chloro-5-methoxy-4H-1,2,6-thiadiazin-4-one (9) with Na2S·9H2O (0.5 equiv) in tetrahydrofuran (THF) at ca. 20 °C for 20 h gives 5,5′-thiobis(3-methoxy-4H-1,2,6-thiadiazin-4-one) (10) in a 44% yield as yellow needles. The compound was fully characterized. Full article
(This article belongs to the Special Issue Heteroatom Rich Organic Heterocycles)
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Figure 1

Short Note
3,5-Bis[5-(thiazol-2-yl)thien-2-yl]-4H-1,2,6-thiadiazin-4-one
Molbank 2019, 2019(1), M1045; https://doi.org/10.3390/M1045 - 15 Jan 2019
Viewed by 881
Abstract
Stille coupling of 3,5-bis(5-bromothien-2-yl)-4H-1,2,6-thiadiazin-4-one (10) with 2-(tri-n-butylstannyl)thiazole and Pd(Ph3P)2Cl2 in PhMe, at ca. 110 °C, for 2 h, gave 3,5-bis[5-(thiazol-2-yl)thien-2-yl]-4H-1,2,6-thiadiazin-4-one (9) in 81% yield. The latter is evaluated for its electronic properties. Full article
(This article belongs to the Special Issue Heteroatom Rich Organic Heterocycles)
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Short Note
3-Chloro-5-(3-n-hexylthien-2-yl)-4H-1,2,6-thiadiazin-4-one
Molbank 2019, 2019(1), M1043; https://doi.org/10.3390/M1043 - 09 Jan 2019
Viewed by 841
Abstract
Stille coupling of 5-chloro-4-oxo-4H-1,2,6-thiadiazin-3-yl trifluoromethanesulfonate (7) with tributyl(3-n-hexylthien-2-yl)stannane and Pd(Ph3P)2Cl2 in PhMe at ca. 20 °C, for 24 h gave 3-chloro-5-(3-n-hexylthien-2-yl)-4H-1,2,6-thiadiazin-4-one (9) with a 60% yield. [...] Read more.
Stille coupling of 5-chloro-4-oxo-4H-1,2,6-thiadiazin-3-yl trifluoromethanesulfonate (7) with tributyl(3-n-hexylthien-2-yl)stannane and Pd(Ph3P)2Cl2 in PhMe at ca. 20 °C, for 24 h gave 3-chloro-5-(3-n-hexylthien-2-yl)-4H-1,2,6-thiadiazin-4-one (9) with a 60% yield. The latter is a potentially useful building block for the synthesis of oligomeric and polymeric donors for organic photovoltaics. Full article
(This article belongs to the Special Issue Heteroatom Rich Organic Heterocycles)
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Figure 1

Short Note
5-Amino-3-(diethylamino)-5H-benzo[4,5]imidazo[1,2-b][1,2,4,6]thiatriazine 1,1-Dioxide
Molbank 2018, 2018(3), M1018; https://doi.org/10.3390/M1018 - 11 Sep 2018
Viewed by 1004
Abstract
In the quest for discovery of novel bioactive molecules, new heterocyclic ring systems provide templates for exploration of uncharted chemical space. Herein, we describe the synthesis of a new benzo[4,5]imidazo[1,2-b][1,2,4,6]thiatriazine derivative from readily available 1,2-diaminobenzimidazole and N,N-diethyl-N [...] Read more.
In the quest for discovery of novel bioactive molecules, new heterocyclic ring systems provide templates for exploration of uncharted chemical space. Herein, we describe the synthesis of a new benzo[4,5]imidazo[1,2-b][1,2,4,6]thiatriazine derivative from readily available 1,2-diaminobenzimidazole and N,N-diethyl-N′-chlorosulfonyl chloroformamidine. The product structure, confirmed by X-ray crystallography, bears an exocyclic NH2 group, which should enable synthesis of an extended range of derivatives of this unusual scaffold. Full article
(This article belongs to the Special Issue Heteroatom Rich Organic Heterocycles)
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Short Note
1-[5-(4-Tolyl)-1,3,4-oxadiazol-2-yl]methanamine
Molbank 2018, 2018(3), M1014; https://doi.org/10.3390/M1014 - 24 Aug 2018
Viewed by 1315
Abstract
1-[5-(4-Tolyl)-1,3,4-oxadiazol-2-yl]methanamine (3) has been successfully synthesized by reacting p-toluic hydrazide (1) and glycine (2) via the polyphosphoric acid condensation route. The course of the reaction was found to be high yielding (87%) and the title compound [...] Read more.
1-[5-(4-Tolyl)-1,3,4-oxadiazol-2-yl]methanamine (3) has been successfully synthesized by reacting p-toluic hydrazide (1) and glycine (2) via the polyphosphoric acid condensation route. The course of the reaction was found to be high yielding (87%) and the title compound was spectroscopically characterized by UV-Vis, FTIR, DSC, 13C/1H-NMR, and sass spectrometric techniques. Full article
(This article belongs to the Special Issue Heteroatom Rich Organic Heterocycles)
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Graphical abstract

Short Note
N-[2-(1H-Indol-3-yl)-1-(5-thioxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)ethyl]-4-methylbenzenesulfonamide
Molbank 2018, 2018(3), M1008; https://doi.org/10.3390/M1008 - 25 Jul 2018
Cited by 1 | Viewed by 1226
Abstract
N-[1-Hydrazinyl-3-(1H-indol-3-yl)-1-oxopropan-2-yl]-4-methylbenzenesulfonamide (1) on cyclization with carbon disulfide in ethanolic potassium hydroxide affords N-[2-(1H-indol-3-yl)-1-(5-thioxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)ethyl]-4-methylbenzenesulfonamide (2) in 84% yield. The structure of compound 2 was supported by mass spectrometry, FT-IR and 1H- and 13 [...] Read more.
N-[1-Hydrazinyl-3-(1H-indol-3-yl)-1-oxopropan-2-yl]-4-methylbenzenesulfonamide (1) on cyclization with carbon disulfide in ethanolic potassium hydroxide affords N-[2-(1H-indol-3-yl)-1-(5-thioxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)ethyl]-4-methylbenzenesulfonamide (2) in 84% yield. The structure of compound 2 was supported by mass spectrometry, FT-IR and 1H- and 13C-NMR spectroscopy. To investigate the potential of compound 2 to act as antitubercular agent, it was docked against the enoyl reductase (InhA) enzyme of Mycobacterium tuberculosis. The docking pose and non-covalent interactions gave insights on its plausible inhibitory action. Full article
(This article belongs to the Special Issue Heteroatom Rich Organic Heterocycles)
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Graphical abstract

Short Note
3,3′-(Diazene-1,2-diyl)bis[4-(nitroamino)-1,2,5-oxadiazole 2-oxide]
Molbank 2018, 2018(3), M1003; https://doi.org/10.3390/M1003 - 05 Jul 2018
Cited by 3 | Viewed by 1203
Abstract
The nitramino derivatives of furoxans are of specific interest as precursors for the preparation of high energy salts with nitrogen-rich cations. In this communication, the 3,3′-(diazene-1,2-diyl)bis[4-(nitroamino)-1,2,5-oxadiazole 2-oxide] was prepared via nitration of available 4,4′-diamino-3,3′-diazenofuroxan; the best yield of the target compound was achieved [...] Read more.
The nitramino derivatives of furoxans are of specific interest as precursors for the preparation of high energy salts with nitrogen-rich cations. In this communication, the 3,3′-(diazene-1,2-diyl)bis[4-(nitroamino)-1,2,5-oxadiazole 2-oxide] was prepared via nitration of available 4,4′-diamino-3,3′-diazenofuroxan; the best yield of the target compound was achieved under the action of nitrating system HNO3/(CF3CO)2O in molar ratio 15:3 in CCl4 at −5 °C. The structure of 3,3′-(diazene-1,2-diyl)bis[4-(nitroamino)-1,2,5-oxadiazole 2-oxide] was confirmed by means of 1H, 13C,14N-NMR, IR spectroscopy and high resolution mass spectra (HRMS). Full article
(This article belongs to the Special Issue Heteroatom Rich Organic Heterocycles)
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Graphical abstract

Communication
5,6,7,8-Tetrafluoro-1-(2-nitrophenyl)-3-phenyl-1H-benzo[e][1,3,4]oxadiazine
Molbank 2018, 2018(2), M997; https://doi.org/10.3390/M997 - 16 May 2018
Viewed by 1041
Abstract
Treating 1-fluoro-2-nitrobenzene (6) with N′-pentafluorophenylbenzohydrazide (7) and K2CO3 (1.1 equiv) in EtOH at ca. 110 °C (sealed tube) for 24 h affords 5,6,7,8-tetrafluoro-1-(2-nitrophenyl)-3-phenyl-1H-benzo[e][1,3,4]oxadiazine (5) (36%) and N′-(2-nitrophenyl)-N [...] Read more.
Treating 1-fluoro-2-nitrobenzene (6) with N′-pentafluorophenylbenzohydrazide (7) and K2CO3 (1.1 equiv) in EtOH at ca. 110 °C (sealed tube) for 24 h affords 5,6,7,8-tetrafluoro-1-(2-nitrophenyl)-3-phenyl-1H-benzo[e][1,3,4]oxadiazine (5) (36%) and N′-(2-nitrophenyl)-N′-(perfluorophenyl)benzohydrazide (3) (37%). The X-ray crystallography of 5,6,7,8-tetrafluoro-1-(2-nitrophenyl)-3-phenyl-1H-benzo[e][1,3,4]oxadiazine (5) is provided. Microwave irradiation (100 W) of perfluorophenylbenzohydrazide 3 with K2CO3 (1.1 equiv) in THF at ca. 120 °C (sealed tube, 80 PSI) for 3 h gives oxadiazine 5 (85%), while reduction of the nitro group using Sn (4 equiv) in glacial acetic acid at ca. 20 °C for 30 min, followed by cyclodehydration at ca. 118 °C for 20 min and treatment with 2 M NaOH for 24 h resulted in 1-(perfluorophenyl)-3-phenyl-1,2,4-benzotriazin-4-yl (4) with 93% yield. Full article
(This article belongs to the Special Issue Heteroatom Rich Organic Heterocycles)
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Short Note
Octahydro-1H,5H,7H-dipyrrolo[1,2-c:1′,2′-f][1,3,6]oxadiazocine-5-thione
Molbank 2018, 2018(2), M993; https://doi.org/10.3390/M993 - 27 Apr 2018
Viewed by 1202
Abstract
A minor byproduct in the reaction of (S)-prolinol with thiophosgene in the presence of triethylamine is identified as a novel tricyclic dipyrrolidino-1,3,6-oxadiazocane-2-thione, the first example of such a ring system, and a representative of the uncommon, but useful 1,3,6-oxadiazocanes. A mechanism [...] Read more.
A minor byproduct in the reaction of (S)-prolinol with thiophosgene in the presence of triethylamine is identified as a novel tricyclic dipyrrolidino-1,3,6-oxadiazocane-2-thione, the first example of such a ring system, and a representative of the uncommon, but useful 1,3,6-oxadiazocanes. A mechanism is proposed for its formation. Full article
(This article belongs to the Special Issue Heteroatom Rich Organic Heterocycles)
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Graphical abstract

Short Note
5,5′-Bis[5-(9-decyl-9H-carbazol-3-yl)thien-2-yl]-4H,4′H-[3,3′-bi(1,2,6-thiadiazine)]-4,4′-dione
Molbank 2018, 2018(1), M987; https://doi.org/10.3390/M987 - 08 Mar 2018
Cited by 2 | Viewed by 1227
Abstract
Stille coupling of 5,5′-dichloro-4H,4′H-[3,3′-bi(1,2,6-thiadiazine)]-4,4′-dione (8) with 9-decyl-3-[5-(tributylstannyl)thien-2-yl]-9H-carbazole and Pd(Ph3P)2Cl2 in PhMe, at ca. 110 °C, for 2 h, gave 5,5′-bis[5-(9-decyl-9H-carbazol-3-yl)thien-2-yl]-4H,4′H-[3,3′-bi(1,2,6-thiadiazine)]-4,4′-dione (7) in 51% yield. The latter is investigated as an oligomer donor for organic photovoltaics. Full article
(This article belongs to the Special Issue Heteroatom Rich Organic Heterocycles)
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Figure 1

Short Note
4,7-Dichloro[1,2,5]oxadiazolo[3,4-d]pyridazine 1-oxide
Molbank 2018, 2018(1), M982; https://doi.org/10.3390/M982 - 18 Feb 2018
Cited by 1 | Viewed by 1490
Abstract
Dihalogenated derivatives of [1,2,5]chalcogenadiazolo[3,4-d]pyridazines are of interest as precursors for both photovoltaic materials and biologically active compounds. In this communication, 4,7-dichloro[1,2,5]oxadiazolo[3,4-d]pyridazine 1-oxide was prepared via the reaction of 3,6-dichloro-5-nitropyridazin-4-amine with oxidizing agents; the best yield of the target compound [...] Read more.
Dihalogenated derivatives of [1,2,5]chalcogenadiazolo[3,4-d]pyridazines are of interest as precursors for both photovoltaic materials and biologically active compounds. In this communication, 4,7-dichloro[1,2,5]oxadiazolo[3,4-d]pyridazine 1-oxide was prepared via the reaction of 3,6-dichloro-5-nitropyridazin-4-amine with oxidizing agents; the best yield of the target compound was achieved in the reaction with (diacetoxyiodo)benzene in benzene by heating at reflux for two hours. The structure of the newly synthesized compound was established by means of 13C-NMR and IR spectroscopy, mass-spectrometry and elemental analysis. Full article
(This article belongs to the Special Issue Heteroatom Rich Organic Heterocycles)
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Scheme 1

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