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Heterocyclic and Organometallic Chemistry: Theme Issue in Honor of Prof. Daniel Comins’ Great Contribution

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Organometallic Chemistry".

Deadline for manuscript submissions: closed (31 May 2022) | Viewed by 35475

Special Issue Editors


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Guest Editor
Pharmacology and Chemical Biology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX, USA
Interests: synthetic organic chemistry; fragment-based drug discovery; diversity-oriented synthesis; medicinal chemistry; chemical biology

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Guest Editor
Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, KY 40292, USA
Interests: Organic Synthesis; Medicinal Chemistry; Natural Products

Special Issue Information

Dear Colleagues,

Molecules is inviting articles for a special issue in honor of Prof. Daniel L. Comins of North Carolina State University. Professor Comins’ research has spanned more than 40 years devoted toward nitrogen-containing heterocyclic methodology and natural product total synthesis. (For an overview of Professor Comins’ significant research accomplishments, please visit: https://cominsresearch.wordpress.ncsu.edu/). Over the course of his illustrious research career, he has trained scores of graduate students and postdoctoral fellows who have themselves gone on to productive careers within the pharmaceutical arena and academia. Prof. Comins served as President of the International Society of Heterocyclic Chemistry (ISHC) from 2013-2015, exemplifying his strong commitment to leadership and service.

In honor of his distinguished scientific career, we invite you to contribute a primary research article (full paper or communication) in the broadly defined areas of heterocyclic and organometallic chemistry as applied to heterocycles to be published in Molecules. To be included in the special edition, we respectfully request that your article be sent to us for review by 31 May 2022. Also, if you will be able to contribute an article by this date, please notify us at your earliest convenience. We look forward to working with you to commemorate Prof. Comins’ outstanding career.

Dr. Damian Winston Young
Prof. Dr. Frederick A. Luzzio
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • heterocycles
  • organic synthesis
  • medicinal chemistry
  • natural products

Published Papers (14 papers)

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Research

Jump to: Review

8 pages, 1822 KiB  
Communication
Copper(I)-Catalyzed Cross-Coupling of 1-Bromoalkynes with N-Heterocyclic Organozinc Reagents
by Christian Frabitore, Jérome Lépeule and Tom Livinghouse
Molecules 2022, 27(14), 4561; https://doi.org/10.3390/molecules27144561 - 17 Jul 2022
Cited by 2 | Viewed by 1390
Abstract
Nitrogen-containing heterocycles represent the majority of FDA-approved small-molecule pharmaceuticals. Herein, we describe a synthetic method to produce saturated N-heterocyclic drug scaffolds with an internal alkyne for elaboration. The treatment of N,N-dimethylhydrazinoalkenes with Et2Zn, followed by a Cu(I)-catalyzed cross-coupling with 1-bromoalkynes, results [...] Read more.
Nitrogen-containing heterocycles represent the majority of FDA-approved small-molecule pharmaceuticals. Herein, we describe a synthetic method to produce saturated N-heterocyclic drug scaffolds with an internal alkyne for elaboration. The treatment of N,N-dimethylhydrazinoalkenes with Et2Zn, followed by a Cu(I)-catalyzed cross-coupling with 1-bromoalkynes, results in piperidines and pyrrolidines with a good yield. Five examples are reported and a proposed mechanism for the Cu(I)-catalyzed cross-coupling is presented. Full article
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8 pages, 1451 KiB  
Article
A Concise Synthetic Method for Constructing 3-Substituted Piperazine-2-Acetic Acid Esters from 1,2-Diamines
by Srinivas Chamakuri, Sunny Ann Tang, Kevin A. Tran, Shiva Krishna Reddy Guduru, Peter K. Bolin, Kevin R. MacKenzie and Damian W. Young
Molecules 2022, 27(11), 3419; https://doi.org/10.3390/molecules27113419 - 25 May 2022
Cited by 4 | Viewed by 2170
Abstract
We report a short synthetic route for synthesizing 2,3-substituted piperazine acetic acid esters. Optically pure amino acids were efficiently converted into 1,2-diamines that could be utilized to deliver the title 2,3-substituted piperazines in five steps with a high enantiomeric purity. The novel route [...] Read more.
We report a short synthetic route for synthesizing 2,3-substituted piperazine acetic acid esters. Optically pure amino acids were efficiently converted into 1,2-diamines that could be utilized to deliver the title 2,3-substituted piperazines in five steps with a high enantiomeric purity. The novel route facilitated, for the first time, the synthesis of 3-phenyl substituted-2-piperazine acetic acid esters that were difficult to achieve using other methods; however, in this case, the products underwent racemization. Full article
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23 pages, 2392 KiB  
Article
Further Studies on the [1,2]-Wittig Rearrangement of 2-(2-Benzyloxy)aryloxazolines
by R. Alan Aitken, Andrew D. Harper and Ryan A. Inwood
Molecules 2022, 27(10), 3186; https://doi.org/10.3390/molecules27103186 - 17 May 2022
Cited by 4 | Viewed by 1706
Abstract
The behaviour of 14 ortho-functionalised 2-aryloxazolines (11 of them prepared and characterised for the first time) with butyllithium has been examined. Significant limitations to the Wittig rearrangement of such systems are revealed. In terms of asymmetric Wittig rearrangement, good diastereoselectivity is obtained with [...] Read more.
The behaviour of 14 ortho-functionalised 2-aryloxazolines (11 of them prepared and characterised for the first time) with butyllithium has been examined. Significant limitations to the Wittig rearrangement of such systems are revealed. In terms of asymmetric Wittig rearrangement, good diastereoselectivity is obtained with a valine-derived 4-isopropyl oxazoline, but this is compromised by racemisation upon hydrolysis. More encouraging selectivity is achieved in the Wittig rearrangement of an acyclic phenylalanine-derived ortho-benzyloxy benzamide. Full article
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10 pages, 3874 KiB  
Article
Stereoselective Synthesis of β-Glycinamide Ribonucleotide
by Lisa Ngu, Debarpita Ray, Samantha S. Watson, Penny J. Beuning, Mary Jo Ondrechen and George A. O’Doherty
Molecules 2022, 27(8), 2528; https://doi.org/10.3390/molecules27082528 - 14 Apr 2022
Viewed by 1547
Abstract
A diastereoselective synthesis of the β-anomer of glycinamide ribonucleotide (β-GAR) has been developed. The synthesis was accomplished in nine steps from D-ribose and occurred in 5% overall yield. The route provided material on the multi-milligram scale. The synthetic β-GAR formed was remarkably resistant [...] Read more.
A diastereoselective synthesis of the β-anomer of glycinamide ribonucleotide (β-GAR) has been developed. The synthesis was accomplished in nine steps from D-ribose and occurred in 5% overall yield. The route provided material on the multi-milligram scale. The synthetic β-GAR formed was remarkably resistant to anomerization both in solution and as a solid. Full article
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10 pages, 1156 KiB  
Article
Concise Syntheses of Marine (Bis)indole Alkaloids Meridianin C, D, F, and G and Scalaridine A via One-Pot Masuda Borylation-Suzuki Coupling Sequence
by Marco Kruppa, Gereon A. Sommer and Thomas J. J. Müller
Molecules 2022, 27(7), 2233; https://doi.org/10.3390/molecules27072233 - 30 Mar 2022
Cited by 9 | Viewed by 2232
Abstract
N-Protected 3-iodoindoles were reacted with (di)azine halides in a sequentially Pd-catalyzed one-pot fashion, i.e., by Masuda borylation–Suzuki coupling (MBSC) sequence. This methodology was successfully applied to the concise syntheses of marine indole alkaloids meridianin C, D, F, and G, as well as [...] Read more.
N-Protected 3-iodoindoles were reacted with (di)azine halides in a sequentially Pd-catalyzed one-pot fashion, i.e., by Masuda borylation–Suzuki coupling (MBSC) sequence. This methodology was successfully applied to the concise syntheses of marine indole alkaloids meridianin C, D, F, and G, as well as to the bisindole alkaloid scalaridine A, which were obtained in moderate to excellent yield. Full article
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10 pages, 1138 KiB  
Article
Synthesis of MAPA Reagents and 2-Alkyl(aryl)aminopyridines from 2-Bromopyridine Using the Goldberg Reaction
by Daniel L. Comins
Molecules 2022, 27(6), 1833; https://doi.org/10.3390/molecules27061833 - 11 Mar 2022
Cited by 2 | Viewed by 2435
Abstract
A short and economical synthesis of various 2-methylaminopyidine amides (MAPA) from 2-bromopyridine has been developed using the catalytic Goldberg reaction. The effective catalyst was formed in situ by the reaction of CuI and 1,10-phenanthroline in a 1/1 ratio with a final loading of [...] Read more.
A short and economical synthesis of various 2-methylaminopyidine amides (MAPA) from 2-bromopyridine has been developed using the catalytic Goldberg reaction. The effective catalyst was formed in situ by the reaction of CuI and 1,10-phenanthroline in a 1/1 ratio with a final loading of 0.5–3 mol%. The process affords high yields and can accommodate multigram-scale reactions. A modification of this method provides a new preparation of 2-N-substituted aminopyridines from various secondary N-alkyl(aryl)formamides and 2-bromopyridine. The intermediate aminopyridine formamide is cleaved in situ through methanolysis or hydrolysis to give 2-alkyl(aryl)aminopyridines in high yields. Full article
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18 pages, 4632 KiB  
Article
Completion of the Total Synthesis of Several Bioactive Sarpagine/Macroline Alkaloids including the Important NF-κB Inhibitor N4-Methyltalpinine
by Md Toufiqur Rahman, Veera Venkata Naga Phani Babu Tiruveedhula, Michael Rajesh Stephen, Sundari K. Rallapalli, Kamal P. Pandey and James M. Cook
Molecules 2022, 27(5), 1738; https://doi.org/10.3390/molecules27051738 - 07 Mar 2022
Cited by 3 | Viewed by 1896
Abstract
The unification of the general synthetic strategy regarding the important and emerging group of C-19 methyl-substituted sarpagine/macroline alkaloids has culminated in the completion of the total synthesis of several bioactive alkaloids. Key transformations include an ACE-Cl mediated late-stage N(4)-demethylation and an anhydrous acid-mediated [...] Read more.
The unification of the general synthetic strategy regarding the important and emerging group of C-19 methyl-substituted sarpagine/macroline alkaloids has culminated in the completion of the total synthesis of several bioactive alkaloids. Key transformations include an ACE-Cl mediated late-stage N(4)-demethylation and an anhydrous acid-mediated intramolecular quaternary hemiaminal formation between a tertiary amine and an aldehyde function to allow efficient access to several biologically important alkaloids from this group. Herein, the enantiospecific total synthesis of the first known sarpagine/macroline alkaloid with NF-κB inhibitory activity, N(4)-methyltalpinine (as a chloride salt), as well as the anticancer alkaloids talpinine, O-acetyltalpinine, and macrocarpines F–G, are described. Full article
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15 pages, 3436 KiB  
Article
One-Pot Synthesis of Novel 2-Imino-5-Arylidine-Thiazolidine Analogues and Evaluation of Their Anti-Proliferative Activity against MCF7 Breast Cancer Cell Line
by Marian N. Aziz, Arzoo Patel, Amany Iskander, Avisankar Chini, Delphine Gout, Subhrangsu S. Mandal and Carl J. Lovely
Molecules 2022, 27(3), 841; https://doi.org/10.3390/molecules27030841 - 27 Jan 2022
Cited by 2 | Viewed by 2685
Abstract
An efficient surface-mediated synthetic method to facilitate access to a novel class of thiazolidines is described. The rationale behind the design of the targeted thiazolidines was to prepare stable thiazolidine analogues and evaluate their anti-proliferative activity against a breast cancer cell line (MCF7). [...] Read more.
An efficient surface-mediated synthetic method to facilitate access to a novel class of thiazolidines is described. The rationale behind the design of the targeted thiazolidines was to prepare stable thiazolidine analogues and evaluate their anti-proliferative activity against a breast cancer cell line (MCF7). Most of the synthesized analogues exhibited increased potency ranging from 2–15-fold higher compared to the standard reference, cisplatin. The most active thiazolidines contain a halogenated or electron withdrawing group attached to the N-phenyl ring of exocyclic 2-imino group. However, combination of the two substituents did not enhance the activity. The anti-proliferative activity was measured in terms of IC50 values using an MTT assay. Full article
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11 pages, 920 KiB  
Article
An Oxidation Study of Phthalimide-Derived Hydroxylactams
by Bernard L. Adjei and Frederick A. Luzzio
Molecules 2022, 27(2), 548; https://doi.org/10.3390/molecules27020548 - 15 Jan 2022
Cited by 2 | Viewed by 2256
Abstract
A systematic study of the oxidation of 3-hydroxy-2-substituted isoindolin-1-ones (hydroxylactams) and their conversion to the corresponding phthalimides was undertaken using three oxidants. Of special interest was the introduction of nickel peroxide (NiO2) as an oxidation system for hydroxylactams and comparison of [...] Read more.
A systematic study of the oxidation of 3-hydroxy-2-substituted isoindolin-1-ones (hydroxylactams) and their conversion to the corresponding phthalimides was undertaken using three oxidants. Of special interest was the introduction of nickel peroxide (NiO2) as an oxidation system for hydroxylactams and comparison of its performance with the commonly used pyridinium chlorochromate (PCC) and iodoxybenzoic acid (IBX) reagents. Using a range of hydroxylactams, optimal conversions of these substrates to the corresponding imides was achieved with 50 equivalents of freshly prepared NiO2 in refluxing toluene over 5–32 h reaction times. By comparison, oxidations of the same substrates using PCC/silica gel (three equivalents) and IBX (three equivalents) required oxidation times of 1–3 h for full conversion but required lengthier purification. While nominal amounts (~25 mg) of substrate hydroxylactams were used to ascertain conversion, scale-up procedures using all three methods gave good to excellent isolated yields of imides. Full article
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13 pages, 5166 KiB  
Article
Photoredox-Catalyzed Giese Reactions: Decarboxylative Additions to Cyclic Vinylogous Amides and Esters
by Kevin Dykstra, Alexei Buevich, Qi Gao, Yu-Hong Lam and Jeffrey T. Kuethe
Molecules 2022, 27(2), 417; https://doi.org/10.3390/molecules27020417 - 10 Jan 2022
Viewed by 1716
Abstract
An effective strategy has been developed for the photoredox-catalyzed decarboxylative addition of cyclic amino acids to both vinylogous amides and esters leading to uniquely substituted heterocycles. The additions take place exclusively trans to the substituent present on the dihydropyridone ring affording stereochemical control [...] Read more.
An effective strategy has been developed for the photoredox-catalyzed decarboxylative addition of cyclic amino acids to both vinylogous amides and esters leading to uniquely substituted heterocycles. The additions take place exclusively trans to the substituent present on the dihydropyridone ring affording stereochemical control about the new carbon-carbon bond. These reactions are operationally simplistic and afford the desired products in good to excellent isolated yields. Full article
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11 pages, 1520 KiB  
Article
Intramolecular Aminolactonization for Synthesis of Furoindolin-2-One
by Kazuhiro Higuchi, Kazunori Matsumura, Takafumi Arai, Motoki Ito and Shigeo Sugiyama
Molecules 2022, 27(1), 102; https://doi.org/10.3390/molecules27010102 - 24 Dec 2021
Viewed by 2123
Abstract
Propellanes are polycyclic compounds in which tricyclic systems share one carbon–carbon single bond. Propellane frameworks that consist of larger sized rings are found in a variety of natural products. As an approach to the stereoselective synthesis of the propellane framework, one of the [...] Read more.
Propellanes are polycyclic compounds in which tricyclic systems share one carbon–carbon single bond. Propellane frameworks that consist of larger sized rings are found in a variety of natural products. As an approach to the stereoselective synthesis of the propellane framework, one of the efficient methods is forming several rings in a single operation. Lapidilectine B (1) is composed of a propellane framework and was synthesized through the oxidative cyclization of trisubstituted alkenes. When the alkene with an ester moiety was treated with N-iodosuccinimide (NIS), iodocyclization proceeded to give the cyclic carbamate. On the other hand, when PhI(OAc)2 was allowed to react in the carboxyl form, a furoindolin-2-one structure corresponding to the A-B-C ring of lapidilectine B (1) was produced. Furthermore, when Pd(OAc)2 catalyst was used for cyclization under oxidative conditions, the product yield was improved. Full article
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18 pages, 1850 KiB  
Article
In Search of Small Molecules That Selectively Inhibit MBOAT4
by Emily S. Murzinski, Ishika Saha, Hui Ding, David Strugatsky, Ryan A. Hollibaugh, Haixia Liu, Peter Tontonoz and Patrick G. Harran
Molecules 2021, 26(24), 7599; https://doi.org/10.3390/molecules26247599 - 15 Dec 2021
Cited by 2 | Viewed by 2645
Abstract
Ghrelin is a 28-residue peptide hormone produced by stomach P/D1 cells located in oxyntic glands of the fundus mucosa. Post-translational octanoylation of its Ser-3 residue, catalyzed by MBOAT4 (aka ghrelin O-acyl transferase (GOAT)), is essential for the binding of the hormone to [...] Read more.
Ghrelin is a 28-residue peptide hormone produced by stomach P/D1 cells located in oxyntic glands of the fundus mucosa. Post-translational octanoylation of its Ser-3 residue, catalyzed by MBOAT4 (aka ghrelin O-acyl transferase (GOAT)), is essential for the binding of the hormone to its receptor in target tissues. Physiological roles of acyl ghrelin include the regulation of food intake, growth hormone secretion from the pituitary, and inhibition of insulin secretion from the pancreas. Here, we describe a medicinal chemistry campaign that led to the identification of small lipopeptidomimetics that inhibit GOAT in vitro. These molecules compete directly for substrate binding. We further describe the synthesis of heterocyclic inhibitors that compete at the acyl coenzyme A binding site. Full article
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16 pages, 2621 KiB  
Article
Total Synthesis of Decahydroquinoline Poison Frog Alkaloids ent-cis-195A and cis-211A
by Takuya Okada, Naizhen Wu, Katsuki Takashima, Jungoh Ishimura, Hiroyuki Morita, Takuya Ito, Takeshi Kodama, Yuhei Yamasaki, Shin-ichi Akanuma, Yoshiyuki Kubo, Ken-ichi Hosoya, Hiroshi Tsuneki, Tsutomu Wada, Toshiyasu Sasaoka, Takahiro Shimizu, Hideki Sakai, Linda P. Dwoskin, Syed R. Hussaini, Ralph A. Saporito and Naoki Toyooka
Molecules 2021, 26(24), 7529; https://doi.org/10.3390/molecules26247529 - 12 Dec 2021
Cited by 4 | Viewed by 3385
Abstract
The total synthesis of two decahydroquinoline poison frog alkaloids ent-cis-195A and cis-211A were achieved in 16 steps (38% overall yield) and 19 steps (31% overall yield), respectively, starting from known compound 1. Both alkaloids were synthesized from [...] Read more.
The total synthesis of two decahydroquinoline poison frog alkaloids ent-cis-195A and cis-211A were achieved in 16 steps (38% overall yield) and 19 steps (31% overall yield), respectively, starting from known compound 1. Both alkaloids were synthesized from the common key intermediate 11 in a divergent fashion, and the absolute stereochemistry of natural cis-211A was determined to be 2R, 4aR, 5R, 6S, and 8aS. Interestingly, the absolute configuration of the parent decahydroquinoline nuclei of cis-211A was the mirror image of that of cis-195A, although both alkaloids were isolated from the same poison frog species, Oophaga (Dendrobates) pumilio, from Panama. Full article
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Review

Jump to: Research

24 pages, 3323 KiB  
Review
Pyrazine and Phenazine Heterocycles: Platforms for Total Synthesis and Drug Discovery
by Robert W. Huigens III, Beau R. Brummel, Srinivasarao Tenneti, Aaron T. Garrison and Tao Xiao
Molecules 2022, 27(3), 1112; https://doi.org/10.3390/molecules27031112 - 07 Feb 2022
Cited by 24 | Viewed by 5295
Abstract
There are numerous pyrazine and phenazine compounds that demonstrate biological activities relevant to the treatment of disease. In this review, we discuss pyrazine and phenazine agents that have shown potential therapeutic value, including several clinically used agents. In addition, we cover some basic [...] Read more.
There are numerous pyrazine and phenazine compounds that demonstrate biological activities relevant to the treatment of disease. In this review, we discuss pyrazine and phenazine agents that have shown potential therapeutic value, including several clinically used agents. In addition, we cover some basic science related to pyrazine and phenazine heterocycles, which possess interesting reactivity profiles that have been on display in numerous cases of innovative total synthesis approaches, synthetic methodologies, drug discovery efforts, and medicinal chemistry programs. The majority of this review is focused on presenting instructive total synthesis and medicinal chemistry efforts of select pyrazine and phenazine compounds, and we believe these incredible heterocycles offer promise in medicine. Full article
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