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Smith BP, Truax NJ, Pollatos AS, Meanwell M, Bedekar P, Garrido-Castro AF, Baran PS. Total Synthesis of Dragocins A-C through Electrochemical Cyclization. Angew Chem Int Ed Engl 2024; 63:e202401107. [PMID: 38358802 DOI: 10.1002/anie.202401107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 02/14/2024] [Accepted: 02/15/2024] [Indexed: 02/16/2024]
Abstract
The first total synthesis of dragocins A-C, remarkable natural products containing an unusual C4' oxidized ribose architecture bridged by a polyhydroxylated pyrrolidine, is presented through a route featuring a number of uncommon maneuvers. Several generations towards the target molecules are presented, including the spectacular failure of a key C-H oxidation on a late-stage intermediate. The final route features rapid, stereocontrolled access to a densely functionalized pyrrolidine and an unprecedented diastereoselective oxidative electrochemical cyclization to forge the hallmark 9-membered ring. Preliminary studies suggest this electrochemical oxidation protocol is generally useful.
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Affiliation(s)
- Brendyn P Smith
- Department of Chemistry, Scripps Research, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
| | - Nathanyal J Truax
- Department of Chemistry, Scripps Research, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
| | - Alexandros S Pollatos
- Department of Chemistry, Scripps Research, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
| | - Michael Meanwell
- Department of Chemistry, Scripps Research, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr NW, Edmonton, AB T6G 2N4, Canada
| | - Pranali Bedekar
- Department of Chemistry, Scripps Research, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
| | - Alberto F Garrido-Castro
- Department of Chemistry, Scripps Research, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093, Zürich, Switzerland
| | - Phil S Baran
- Department of Chemistry, Scripps Research, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
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Truax NJ, Ayinde S, Liu JO, Romo D. Total Synthesis of Rameswaralide Utilizing a Pharmacophore-Directed Retrosynthetic Strategy. J Am Chem Soc 2022; 144:18575-18585. [PMID: 36166374 DOI: 10.1021/jacs.2c08245] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A pharmacophore-directed retrosynthetic strategy was applied to the first total synthesis of the cembranoid rameswaralide in order to simultaneously achieve a total synthesis while also developing a structure-activity relationship profile throughout the synthetic effort. The synthesis utilized a Diels-Alder lactonization process, including a rare kinetic resolution to demonstrate the potential of this strategy for an enantioselective synthesis providing both the 5,5,6- and, through a ring expansion, 5,5,7-tricyclic ring systems present in several Sinularia soft coral cembranoids. A pivotal synthetic intermediate, a tricyclic epoxy α-bromo cycloheptenone, displayed high cytotoxicity with interesting selectivity toward the HCT-116 colon cancer cell line. This intermediate enabled the pursuit of three unique D-ring annulation strategies including a photocatalyzed intramolecular Giese-type radical cyclization and a diastereoselective, intramolecular enamine-mediated Michael addition, with the latter annulation constructing the final D-ring to deliver rameswaralide. The serendipitous discovery of an oxidation state transposition of the tricyclic epoxy cycloheptenone proceeding through a presumed doubly vinylogous, E1-type elimination enabled the facile introduction of the required α-methylene butyrolactone. Preliminary biological tests of rameswaralide and precursors demonstrated weak cytotoxicity; however, the comparable cytotoxicity of a simple 6,7-bicyclic β-keto ester, corresponding to the CD-ring system of rameswaralide, to that of the natural product itself suggests that such bicyclic β-ketoesters may constitute an interesting pharmacophore that warrants further exploration.
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Affiliation(s)
- Nathanyal J Truax
- Department of Chemistry & Biochemistry, Baylor University, 101 Bagby Avenue, Waco, Texas 76710, United States
| | - Safiat Ayinde
- Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, Maryland 21205, United States
| | - Jun O Liu
- Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, Maryland 21205, United States
| | - Daniel Romo
- Department of Chemistry & Biochemistry, Baylor University, 101 Bagby Avenue, Waco, Texas 76710, United States
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Mowery P, Filkorn MM, Hurysz B, Kwansare DO, Lafferty MM, McFadden MA, Neerukonda ND, Patel RR, Pierce K, Sockett KA, Truax NJ, Webster NR, Pelkey ET. Discovery of an indole-substituted furanone with tubulin polymerization inhibition activity. Bioorg Med Chem Lett 2021; 41:127991. [PMID: 33775833 DOI: 10.1016/j.bmcl.2021.127991] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 03/16/2021] [Accepted: 03/18/2021] [Indexed: 11/17/2022]
Abstract
Analogs of diarylpyrrolinone lead compound 1 were prepared and tested for anti-proliferative activity in U-937 cancer cells. Alterations of 1 focused on modifying the two nitrogen atoms: a) the pyrrolinone nitrogen atom was substituted with a propyl group or replaced with an oxygen atom (furanone), and b) the substituents on the indole nitrogen were varied. These changes led to the discovery of a furanone analog 3b with sub-micromolar anti-cancer potency and tubulin polymerization inhibition activity.
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Affiliation(s)
- Patricia Mowery
- Department of Biology, Hobart and William Smith Colleges, Geneva, NY 14456, USA.
| | - Madison M Filkorn
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Brianna Hurysz
- Department of Biology, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Deborah O Kwansare
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Megan M Lafferty
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Marissa A McFadden
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Namita D Neerukonda
- Department of Biology, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Roslyn R Patel
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Kelsey Pierce
- Department of Biology, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Kaitlynn A Sockett
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Nathanyal J Truax
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Nathan R Webster
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Erin T Pelkey
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, NY 14456, USA.
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El Atab O, Darwiche R, Truax NJ, Schneiter R, Hull KG, Romo D, Asojo OA. Necator americanus Ancylostoma Secreted Protein-2 ( Na-ASP-2) Binds an Ascaroside (ascr#3) in Its Fatty Acid Binding Site. Front Chem 2020; 8:608296. [PMID: 33392151 PMCID: PMC7773830 DOI: 10.3389/fchem.2020.608296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Accepted: 11/25/2020] [Indexed: 11/28/2022] Open
Abstract
During their infective stages, hookworms release excretory-secretory (E-S) products, small molecules, and proteins to help evade and suppress the host's immune system. Small molecules found in E-S products of mammalian hookworms include nematode derived metabolites like ascarosides, which are composed of the sugar ascarylose linked to a fatty acid side chain. The most abundant proteins found in hookworm E-S products are members of the protein family known as Ancylostoma secreted protein (ASP). In this study, two ascarosides and their fatty acid moieties were synthesized and tested for in vitro binding to Na-ASP-2 using both a ligand competition assay and microscale thermophoresis. The fatty acid moieties of both ascarosides tested and ascr#3, an ascaroside found in rat hookworm E-S products, bind to Na-ASP-2's palmitate binding cavity. These molecules were confirmed to bind to the palmitate but not the sterol binding sites. An ascaroside, oscr#10, which is not found in hookworm E-S products, does not bind to Na-ASP-2. More studies are required to determine the structural basis of ascarosides binding by Na-ASP-2 and to understand the physiological significance of these observations.
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Affiliation(s)
- Ola El Atab
- Division of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Rabih Darwiche
- Division of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States
| | - Nathanyal J. Truax
- Department of Chemistry and Biochemistry & The CPRIT Synthesis and Drug-Lead Discovery Laboratory, Baylor University, Waco, TX, United States
| | - Roger Schneiter
- Division of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Kenneth G. Hull
- Department of Chemistry and Biochemistry & The CPRIT Synthesis and Drug-Lead Discovery Laboratory, Baylor University, Waco, TX, United States
| | - Daniel Romo
- Department of Chemistry and Biochemistry & The CPRIT Synthesis and Drug-Lead Discovery Laboratory, Baylor University, Waco, TX, United States
| | - Oluwatoyin A. Asojo
- Department of Chemistry and Biochemistry, Hampton University, Hampton, VA, United States
- National School of Tropical Medicine, Baylor College of Medicine, Houston, TX, United States
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Abstract
Covering: 1986 to 2020Natural products are an enduring source of chemical information useful for probing biologically relevant chemical space. Toward gathering further structure-activity relationship (SAR) information for a particular natural product, synthetic chemists traditionally proceeded first by a total synthesis effort followed by the synthesis of simplified derivatives. While this approach has proven fruitful, it often does not incorporate hypotheses regarding structural features necessary for bioactivity at the synthetic planning stage, but rather focuses on the rapid assembly of the targeted natural product; a goal that often supersedes the opportunity to gather SAR information en route to the natural product. Furthermore, access to simplified variants of a natural product possessing only the proposed essential structural features necessary for bioactivity, typically at lower oxidation states overall, is sometimes non-trivial from the original established synthetic route. In recent years, several synthetic design strategies were described to streamline the process of finding bioactive molecules in concert with fathering further SAR studies for targeted natural products. This review article will briefly discuss traditional retrosynthetic strategies and contrast them to selected examples of recent synthetic strategies for the investigation of biologically relevant chemical space revealed by natural products. These strategies include: diversity-oriented synthesis (DOS), biology-oriented synthesis (BIOS), diverted-total synthesis (DTS), analogue-oriented synthesis (AOS), two-phase synthesis, function-oriented synthesis (FOS), and computed affinity/dynamically ordered retrosynthesis (CANDOR). Finally, a description of pharmacophore-directed retrosynthesis (PDR) developed in our laboratory and initial applications will be presented that was initially inspired by a retrospective analysis of our synthetic route to pateamine A completed in 1998.
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Affiliation(s)
- Nathanyal J Truax
- Department of Chemistry & Biochemistry, Baylor University, Waco, Texas 76710, USA.
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Truax NJ, Ayinde S, Van K, Liu JO, Romo D. Pharmacophore-Directed Retrosynthesis Applied to Rameswaralide: Synthesis and Bioactivity of Sinularia Natural Product Tricyclic Cores. Org Lett 2019; 21:7394-7399. [PMID: 31498642 DOI: 10.1021/acs.orglett.9b02713] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A pharmacophore-directed retrosynthesis strategy applied to rameswaralide provided simplified precursors bearing the common 5,5,6 (red) and 5,5,7 (blue) skeleton present in several cembranoid and norcembranoids from Sinularia soft corals. Key steps include a Diels-Alder lactonization organocascade delivering the common 5,5,6 core and a subsequent ring expansion affording a 5,5,7 core serviceable for the synthesis of rameswaralide. Initial structure-activity relationships of intermediates en route to the natural product have revealed interesting differential and selective cytotoxicity.
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Affiliation(s)
- Nathanyal J Truax
- Department of Chemistry & Biochemistry , Baylor University , Waco , Texas 76710 , United States
| | - Safiat Ayinde
- Department of Pharmacology and Molecular Sciences , John Hopkins School of Medicine , 725 North Wolfe Street , Baltimore , Maryland 21205 , United States
| | - Khoi Van
- Department of Chemistry & Biochemistry , Baylor University , Waco , Texas 76710 , United States
| | - Jun O Liu
- Department of Pharmacology and Molecular Sciences , John Hopkins School of Medicine , 725 North Wolfe Street , Baltimore , Maryland 21205 , United States
| | - Daniel Romo
- Department of Chemistry & Biochemistry , Baylor University , Waco , Texas 76710 , United States
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Mowery P, Banales Mejia F, Franceschi CL, Kean MH, Kwansare DO, Lafferty MM, Neerukonda ND, Rolph CE, Truax NJ, Pelkey ET. Synthesis and evaluation of the anti-proliferative activity of diaryl-3-pyrrolin-2-ones and fused analogs. Bioorg Med Chem Lett 2017; 27:191-195. [PMID: 27916489 DOI: 10.1016/j.bmcl.2016.11.076] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Revised: 11/23/2016] [Accepted: 11/24/2016] [Indexed: 10/20/2022]
Abstract
Analogs containing a central 3-pyrrolin-2-one core with different methoxyphenyl and/or indole substituents were prepared and tested for anti-proliferative activity in U-937 cells. The most efficacious analogs were non-rigid, (non-fused) contained methoxyaryl groups located at the 4-position, and contained either methoxyaryl or indole groups located at the 3-position. Both the number of methoxy groups contained in the substituents and the particular location of the indole rings with respect to the lactam carbonyl had significant affects on anti-proliferative activity. This work provides a framework to better understand structure-activity relationships for inducing anti-proliferative activity in diaryl heterocyclic scaffolds.
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Affiliation(s)
- Patricia Mowery
- Department of Biology, Hobart and William Smith Colleges, Geneva, NY 14456, USA.
| | | | | | - Maeve H Kean
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Deborah O Kwansare
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Megan M Lafferty
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Namita D Neerukonda
- Department of Biology, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Carly E Rolph
- Department of Biology, Hobart and William Smith Colleges, Geneva, NY 14456, USA; Department of Chemistry, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Nathanyal J Truax
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, NY 14456, USA
| | - Erin T Pelkey
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, NY 14456, USA.
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Truax NJ, Banales Mejia F, Kwansare DO, Lafferty MM, Kean MH, Pelkey ET. Synthesis of Benzo[a]carbazoles and an Indolo[2,3-a]carbazole from 3-Aryltetramic Acids. J Org Chem 2016; 81:6808-15. [DOI: 10.1021/acs.joc.6b01072] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Nathanyal J. Truax
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, New York 14456, United States
| | - Fernando Banales Mejia
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, New York 14456, United States
| | - Deborah O. Kwansare
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, New York 14456, United States
| | - Megan M. Lafferty
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, New York 14456, United States
| | - Maeve H. Kean
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, New York 14456, United States
| | - Erin T. Pelkey
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, New York 14456, United States
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