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Molbank
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Heterocycles
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Heterocycles

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

Deadline for manuscript submissions: closed (31 December 2017) | Viewed by 59178

Special Issue Editor

Prof. Dr. Richard A. Bunce

E-Mail Website
Guest Editor
Department of Chemistry, Oklahoma State University, Stillwater, OK, USA
Interests: new synthetic methodology; heterocycles; antibacterial agents; anticancer agents; medicinal chemistry
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Heterocycles are ubiquitous building blocks in natural and unnatural medicinal compounds and functional materials. The focus of this Special Issue is to present short papers describing novel synthetic approaches to heterocyclic structures of value in these areas. Efficient procedures to access ring systems containing one or more heteroatoms (particularly, N, O and S, as well as others) are welcome. Contributions should be written as single-compound preparations and should target new compounds of high value. Previously-described structures will only be considered if they have proven value and if a significant improvement has been made in the synthetic approach. Sufficient experimental details should be included to facilitate other researchers in accessing each compound and characterization data should be included.

Prof. Dr. Richard A. Bunce
Guest Editor

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Keywords

  • heterocycle synthesis
  • novel synthetic strategies
  • natural and unnatural medicinal compounds
  • functional materials chemistry

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Published Papers (13 papers)

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Research

8 pages, 1526 KiB  
Communication
2-[2-Methyl-5-phenyl-1-(3,4,5-trimethoxyphenyl)-1H-pyrrol-3-yl]-2-oxo-N-(pyridin-4-yl) acetamide
by Ebrahim Saeedian Moghadam and Mohsen Amini
Molbank 2018, 2018(3), 1002; https://doi.org/10.3390/M1002 - 28 Jun 2018
Cited by 5 | Viewed by 4283
Abstract
We synthesized 2-[2-methyl-5-phenyl-1-(3,4,5-trimethoxyphenyl)-1H-pyrrol-3-yl]-2-oxo-N-(pyridin-4-yl) acetamide 4 as a novel compound derived from the indibulin and combretastatin scaffolds, which are known anti-mitotic agents, using a multistep reaction. We tested its cytotoxic activity against three breast cancer cell lines, namely, MCF-7, T47-D, [...] Read more.
We synthesized 2-[2-methyl-5-phenyl-1-(3,4,5-trimethoxyphenyl)-1H-pyrrol-3-yl]-2-oxo-N-(pyridin-4-yl) acetamide 4 as a novel compound derived from the indibulin and combretastatin scaffolds, which are known anti-mitotic agents, using a multistep reaction. We tested its cytotoxic activity against three breast cancer cell lines, namely, MCF-7, T47-D, and MDA-MB 231 as well as normal cell line NIH-3T3, by 3-(4,5-dimethylthiazoyl-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The biological activity results showed good cytotoxicity on cancerous cell lines (IC50 value 27.7–39.2 µM) and low toxicity on normal cell line (NIH-3T3, IC50 value > 100 µM). Full article
(This article belongs to the Special Issue Heterocycles)
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7 pages, 2198 KiB  
Communication
1-[1-(4-Chlorobenzenesulfonyl)-1H-indole-3-yl]-3-[4-(pyridin-2-yl)piperazin-1-yl]propan-1-one
by Benjamín Diethelm, Sebastián Almendras and Gonzalo Recabarren-Gajardo
Molbank 2018, 2018(2), M991; https://doi.org/10.3390/M991 - 18 Apr 2018
Cited by 1 | Viewed by 10608
Abstract
The title compound was prepared by an aza-Michael addition reaction between 1-[1-(4-chlorobenzenesulfonyl)-1H-indole-3-yl]prop-2-en-1-one and 2-piridylpiperazine catalyzed by SiO2. The structural identity of the title compound was proven by elemental analysis and spectroscopic methods (IR, NMR). The compound was assayed in [...] Read more.
The title compound was prepared by an aza-Michael addition reaction between 1-[1-(4-chlorobenzenesulfonyl)-1H-indole-3-yl]prop-2-en-1-one and 2-piridylpiperazine catalyzed by SiO2. The structural identity of the title compound was proven by elemental analysis and spectroscopic methods (IR, NMR). The compound was assayed in a binding assay at the 5-HT6 receptor, showing poor affinity. Full article
(This article belongs to the Special Issue Heterocycles)
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Graphical abstract

9 pages, 2260 KiB  
Short Note
(Z)-4-[2-(3,4-Difluorophenyl)hydrazono]-3-methyl-1H-pyrazol-5(4H)-one
by Billava Jayappa Mohan, Balladka Kunhanna Sarojini, Badiadka Narayana and Enumadishetty Srinivasulu Sindhu Priya
Molbank 2018, 2018(2), M989; https://doi.org/10.3390/M989 - 31 Mar 2018
Cited by 2 | Viewed by 3945
Abstract
The title compound (Z)-4-[2-(3,4-difluorophenyl)hydrazono]-3-methyl-1H-pyrazol-5(4H)-one 4 was synthesized by the reaction of ethyl 2-[2-(3,4-difluorophenyl)hydrazono]-3-oxobutanoate 3 with hydrazine hydrate. The diazotization of 3,4-difluoroaniline, followed by the treatment with ethyl acetoacetate, afforded intermediate 3. The synthesized compound 4 was [...] Read more.
The title compound (Z)-4-[2-(3,4-difluorophenyl)hydrazono]-3-methyl-1H-pyrazol-5(4H)-one 4 was synthesized by the reaction of ethyl 2-[2-(3,4-difluorophenyl)hydrazono]-3-oxobutanoate 3 with hydrazine hydrate. The diazotization of 3,4-difluoroaniline, followed by the treatment with ethyl acetoacetate, afforded intermediate 3. The synthesized compound 4 was characterized by FTIR, 1H-NMR, 13C-NMR and LCMS, and it showed synergistic anti-inflammatory, antiproliferative and antibacterial activities. Full article
(This article belongs to the Special Issue Heterocycles)
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Graphical abstract

4 pages, 350 KiB  
Short Note
1,3-Bis{[(E)-(9-ethyl-9H-carbazol-3-yl)methylene]amino}propan-2-ol
by Ismail Warad, Nisreen Amer, Huda Abedalrazeq, Anas Al Ali, Nabil Al-Zaqri, Hicham Elmsellem and Abdelkader Zarrouk
Molbank 2018, 2018(1), M986; https://doi.org/10.3390/M986 - 7 Mar 2018
Cited by 1 | Viewed by 3871
Abstract
Condensation of 1,3-diaminopropan-2-ol with 9-ethyl-9H-carbazole-3-carbaldehyde in absolute ethanol under stirring condition resulted in the formation of 1,3-bis{[(E)-(9-ethyl-9H-carbazol-3-yl)methylidene]amino}propan-2-ol within 0.5 in an excellent yield. The structure of the desired Schiff base was physically analyzed via CHN-elemental analysis, TOF-MS, [...] Read more.
Condensation of 1,3-diaminopropan-2-ol with 9-ethyl-9H-carbazole-3-carbaldehyde in absolute ethanol under stirring condition resulted in the formation of 1,3-bis{[(E)-(9-ethyl-9H-carbazol-3-yl)methylidene]amino}propan-2-ol within 0.5 in an excellent yield. The structure of the desired Schiff base was physically analyzed via CHN-elemental analysis, TOF-MS, UV-vis, FT-IR, and 1H & 13C-NMR. Computational studies of the structure were performed at the DFT/B3LYP/6-311++G(d) level of theory. Molecular electrostatic potential (MEP), Mulliken charge, IR-B3LYP, and structure optimization were performed. Full article
(This article belongs to the Special Issue Heterocycles)
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Graphical abstract

6 pages, 703 KiB  
Communication
N-Vinylation of Imidazole and Benzimidazole with a Paramagnetic Vinyl Bromide
by Györgyi Úr, Gergely Gulyás Fekete, Kálmán Hideg and Tamás Kálai
Molbank 2018, 2018(1), M980; https://doi.org/10.3390/M980 - 1 Feb 2018
Cited by 2 | Viewed by 3796
Abstract
An N-vinylation of imidazole and benzimidazole with a paramagnetic vinyl bromide was investigated. Among the tested procedures, Pd-catalyzed reaction was the most powerful one. The N-vinylation of 2-aminobenzimidazole with a β-bromo-α,β-unsaturated pyrroline nitroxide aldehyde offered 1,1,3,3-tetramethyl-1H-benzimidazo[1,2-a]pyrrolo[3,4-e [...] Read more.
An N-vinylation of imidazole and benzimidazole with a paramagnetic vinyl bromide was investigated. Among the tested procedures, Pd-catalyzed reaction was the most powerful one. The N-vinylation of 2-aminobenzimidazole with a β-bromo-α,β-unsaturated pyrroline nitroxide aldehyde offered 1,1,3,3-tetramethyl-1H-benzimidazo[1,2-a]pyrrolo[3,4-e]pyrimidin-2(3H)-yloxyl radical and the corresponding non-cyclized Schiff base. The reaction of a β-bromo-α,β-unsaturated pyrroline nitroxide aldehyde with imidazole gave β-imidazo-α,β-unsaturated pyrroline nitroxide aldehyde, which was reduced to the alcohol and converted to an unstable allyl chloride. Full article
(This article belongs to the Special Issue Heterocycles)
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Graphical abstract

7 pages, 2042 KiB  
Communication
N-(4-Bromobenzyl)-2-(5,6-dimethyl-1H-benzo[d]imid-azol-2-yl)benzeneamine
by Monika Dziełak, Damian Trzybiński, Jolanta Czerwińska, Bartosz Majchrzak, Barbara Tudek, Krzysztof Woźniak and Adam Mieczkowski
Molbank 2018, 2018(1), M979; https://doi.org/10.3390/M979 - 30 Jan 2018
Cited by 1 | Viewed by 3788
Abstract
N-(4-Bromobenzyl)-2-(5,6-dimethyl-1H-benzo[d]imidazol-2-yl)benzeneamine was obtained by condensation of N-(4-bromobenzyl)-3,1-benzoxazine-2,4-dione (N-(4-bromobenzyl)isatoic anhydride) with 4,5-dimethyl-1,2-phenylenediamine in refluxing acetic acid. This is a rare example of condensation of N-substituted 3,1-benzoxazine-2,4-dione with 1,2-phenylenediamine, which resulted in the formation of a [...] Read more.
N-(4-Bromobenzyl)-2-(5,6-dimethyl-1H-benzo[d]imidazol-2-yl)benzeneamine was obtained by condensation of N-(4-bromobenzyl)-3,1-benzoxazine-2,4-dione (N-(4-bromobenzyl)isatoic anhydride) with 4,5-dimethyl-1,2-phenylenediamine in refluxing acetic acid. This is a rare example of condensation of N-substituted 3,1-benzoxazine-2,4-dione with 1,2-phenylenediamine, which resulted in the formation of a benzimidazole derivative with a moderate yield. Crystallographic studies and initial biological screening were performed for the obtained product. Full article
(This article belongs to the Special Issue Heterocycles)
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Graphical abstract

5 pages, 650 KiB  
Short Note
5-Methyl-3,8-di-(2-amino-4-bromophenyl)-4,9-dioxa-1,2,6,7-tetraaza-5λ5-phosphaspiro[4.4]nona-2,7-diene
by Sławomir Kasperowicz, Jolanta Czerwińska, Bartosz Majchrzak, Barbara Tudek and Adam Mieczkowski
Molbank 2018, 2018(1), M978; https://doi.org/10.3390/M978 - 30 Jan 2018
Viewed by 3352
Abstract
5-Methyl-3,8-di-(2-amino-4-bromophenyl)-4,9-dioxa-1,2,6,7-tetraaza-5λ5-phosphaspiro[4.4]nona-2,7-diene was obtained by condensation of 2-amino-5-bromobenzohydrazide and methylphosphonyl dichloride in the presence of triethylamine. An initial biological screening was performed for the resulting product. The synthesized compound showed relatively strong cytotoxic activity, which was, however, similar for cancer and non-cancer [...] Read more.
5-Methyl-3,8-di-(2-amino-4-bromophenyl)-4,9-dioxa-1,2,6,7-tetraaza-5λ5-phosphaspiro[4.4]nona-2,7-diene was obtained by condensation of 2-amino-5-bromobenzohydrazide and methylphosphonyl dichloride in the presence of triethylamine. An initial biological screening was performed for the resulting product. The synthesized compound showed relatively strong cytotoxic activity, which was, however, similar for cancer and non-cancer cell lines. Full article
(This article belongs to the Special Issue Heterocycles)
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Figure 1

6 pages, 1341 KiB  
Communication
Straightforward Synthesis of N-Methyl-4-(pin)B-2(3H)-benzothiazol-2-one: A Promising Cross-Coupling Reagent
by Shotaro Izawa, Hidefumi Nakatsuji and Yoo Tanabe
Molbank 2018, 2018(1), M976; https://doi.org/10.3390/M976 - 23 Jan 2018
Cited by 2 | Viewed by 4080
Abstract
Cyclo-condensation of N-methyl-2-bromoaniline with chlorocarbonylsulfenyl chloride (CCSC) promoted by PhNMe2 and AlCl3, afforded N-methyl-2-bromo-2(3H)-benzothiazol-2-one in good yield. Miyaura–Ishiyama cross-coupling of this brominated 2(3H)-benzothiazol-2-one with bis(pinacolato)diborone [(pin)2B2] produced a novel N [...] Read more.
Cyclo-condensation of N-methyl-2-bromoaniline with chlorocarbonylsulfenyl chloride (CCSC) promoted by PhNMe2 and AlCl3, afforded N-methyl-2-bromo-2(3H)-benzothiazol-2-one in good yield. Miyaura–Ishiyama cross-coupling of this brominated 2(3H)-benzothiazol-2-one with bis(pinacolato)diborone [(pin)2B2] produced a novel N-methyl-4-(pin)B-2(3H)-benzothiazol-2-one (3) using (pin)2B2 in the presence of the PdCl2(PPh3)2 catalyst. The obtained 4-(pin)B compound is regarded as a new entry for the library of Suzuki–Miyaura cross-coupling reactions. Full article
(This article belongs to the Special Issue Heterocycles)
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Graphical abstract

5 pages, 1305 KiB  
Short Note
5-Amino-3-methyl-1,2,4-thiadiazole
by R. Alan Aitken and Alexandra M. Z. Slawin
Molbank 2018, 2018(1), M977; https://doi.org/10.3390/M977 - 21 Jan 2018
Cited by 1 | Viewed by 4923
Abstract
An improved procedure for isolation of 5-amino-3-methyl-1,2,4-thiadiazole in pure form on a multi-gram scale without chromatography is reported. Its 1H and 13C-NMR and IR data are presented and previously published erroneous data corrected. The molecular structure is confirmed by X-ray diffraction [...] Read more.
An improved procedure for isolation of 5-amino-3-methyl-1,2,4-thiadiazole in pure form on a multi-gram scale without chromatography is reported. Its 1H and 13C-NMR and IR data are presented and previously published erroneous data corrected. The molecular structure is confirmed by X-ray diffraction which shows layers consisting of an elaborate two-dimensional hydrogen bonded network of molecules. Full article
(This article belongs to the Special Issue Heterocycles)
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Graphical abstract

6 pages, 378 KiB  
Communication
3-[2-(Oxiran-2-yl)ethyl]-1-{4-[(2-oxiran-2-yl)ethoxy]benzyl}imidazolium bis(Trifluoromethane)sulfonimide
by Charline Chardin, Jacques Rouden, Sébastien Livi and Jérôme Baudoux
Molbank 2018, 2018(1), M974; https://doi.org/10.3390/M974 - 13 Jan 2018
Cited by 7 | Viewed by 4091
Abstract
The synthesis of 3-[2-(oxiran-2-yl)ethyl]-1-{4-[(2-oxiran-2-yl)ethoxy]benzyl}imidazolium bis(trifluoromethane)sulfonimide was achieved in seven steps with an overall yield of 63%. This ionic liquid monomer is based on an imidazolium core containing a phenoxy moiety and aliphatic chains with a reactive epoxide at both ends. This imidazolium was [...] Read more.
The synthesis of 3-[2-(oxiran-2-yl)ethyl]-1-{4-[(2-oxiran-2-yl)ethoxy]benzyl}imidazolium bis(trifluoromethane)sulfonimide was achieved in seven steps with an overall yield of 63%. This ionic liquid monomer is based on an imidazolium core containing a phenoxy moiety and aliphatic chains with a reactive epoxide at both ends. This imidazolium was obtained by an efficient, reproducible, and scalable synthesis from inexpensive reagents. In the last step, a powerful oxidative agent was successfully used to generate two epoxy functions with only acetone as a byproduct. The monomer structure and intermediates were analyzed by NMR experiments, infrared, and mass spectra. In addition, the thermal properties of the diepoxide were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Full article
(This article belongs to the Special Issue Heterocycles)
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Graphical abstract

2478 KiB  
Short Note
1,3-Bis[(E)-(3-bromobenzylidene)amino]propan-2-ol
by Ismail Warad, Huda Abedalrazeq, Nisreen Amer, Mohammmed Al-Nuri, Anas Al Ali, Nabil Al-Zaqri and Naveen Shivalingegowda
Molbank 2017, 2017(4), M971; https://doi.org/10.3390/M971 - 19 Dec 2017
Cited by 2 | Viewed by 3888
Abstract
1,3-Bis[(E)-(3-bromobenzylidene)amino]propan-2-ol Schiff base was synthesized in an acceptable yield by condensation of 3-bromobenzaldehyde with 1,3-diaminopropan-2-ol in methanol. The structure of the desired Schiff base compound was spectroscopically analyzed by EI-MS, CHN-elemental analysis, FT-IR, UV-visible, and 1H and 13C-NMR. The [...] Read more.
1,3-Bis[(E)-(3-bromobenzylidene)amino]propan-2-ol Schiff base was synthesized in an acceptable yield by condensation of 3-bromobenzaldehyde with 1,3-diaminopropan-2-ol in methanol. The structure of the desired Schiff base compound was spectroscopically analyzed by EI-MS, CHN-elemental analysis, FT-IR, UV-visible, and 1H and 13C-NMR. The structure was also computed by DFT-optimization, MEP, Mulliken, NPA, IR- B3LYP/6-311++G(d), and SCF-TD-DFT. Full article
(This article belongs to the Special Issue Heterocycles)
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Graphical abstract

465 KiB  
Short Note
4-Phenethylthio-2-phenylpyrazolo[1,5-a][1,3,5]triazin-7(6H)-one
by Sergey A. Smolnikov, Ekaterina V. Gorgopina, Vera R. Lezhnyova, Gwyneth En-Tian Ong, Wai-Keung Chui and Anton V. Dolzhenko
Molbank 2017, 2017(4), M970; https://doi.org/10.3390/M970 - 15 Dec 2017
Cited by 7 | Viewed by 3293
Abstract
Exploring the pharmacologically important pyrazolo[1,5-a][1,3,5]triazin-7(6H)-one scaffold for the construction of new bioactive compounds, we developed a synthesis of 4-phenethylthio-2-phenylpyrazolo[1,5-a][1,3,5]triazin-7(6H)-one (4) via S-alkylation of 2-phenyl-4-thioxopyrazolo[1,5-a][1,3,5]triazine-7(6H)-one (3), prepared [...] Read more.
Exploring the pharmacologically important pyrazolo[1,5-a][1,3,5]triazin-7(6H)-one scaffold for the construction of new bioactive compounds, we developed a synthesis of 4-phenethylthio-2-phenylpyrazolo[1,5-a][1,3,5]triazin-7(6H)-one (4) via S-alkylation of 2-phenyl-4-thioxopyrazolo[1,5-a][1,3,5]triazine-7(6H)-one (3), prepared by the double ring closure of pyrazole and triazine rings upon the treatment of 1-cyanoacetyl-4-benzoylthiosemicarbazide (2) with alkali. The antiproliferative activity of 4 against human lung cancer (A549) and human breast cancer (MDA-MB231) cell lines was investigated. Compound 4 was found to be more active against lung cancer cells than breast cancer cells. Full article
(This article belongs to the Special Issue Heterocycles)
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2957 KiB  
Communication
(S)-2-(4-Chlorobenzoyl)-1,2,3,4-tetrahydrobenzo[e]pyrazino[1,2-a][1,4]diazepine-6,12(11H,12aH)-dione—Synthesis and Crystallographic Studies
by Adam Mieczkowski, Damian Trzybiński, Marcin Wilczek, Mateusz Psurski, Maciej Bagiński, Bartosz Bieszczad, Magdalena Mroczkowska and Krzysztof Woźniak
Molbank 2017, 2017(4), M964; https://doi.org/10.3390/M964 - 27 Oct 2017
Cited by 10 | Viewed by 3992
Abstract
(S)-2-(4-Chlorobenzoyl)-1,2,3,4-tetrahydrobenzo[e]pyrazino[1,2-a][1,4]diazepine-6,12(11H,12aH)-dione was obtained in a three-step, one-pot synthesis, starting from optically pure (S)-2-piperazine carboxylic acid dihydrochloride. Selective acylation of the β-nitrogen atom followed by condensation with isatoic anhydride and cyclization [...] Read more.
(S)-2-(4-Chlorobenzoyl)-1,2,3,4-tetrahydrobenzo[e]pyrazino[1,2-a][1,4]diazepine-6,12(11H,12aH)-dione was obtained in a three-step, one-pot synthesis, starting from optically pure (S)-2-piperazine carboxylic acid dihydrochloride. Selective acylation of the β-nitrogen atom followed by condensation with isatoic anhydride and cyclization with HATU/DIPEA to a seven-member benzodiazepine ring, led to the tricyclic benzodiazepine derivative. Crystallographic studies and initial biological screening were performed for the title compound. Full article
(This article belongs to the Special Issue Heterocycles)
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