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HIRAMA M. Total synthesis and related studies of large, strained, and bioactive natural products. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2016; 92:290-329. [PMID: 27725470 PMCID: PMC5243947 DOI: 10.2183/pjab.92.290] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 08/10/2016] [Indexed: 06/06/2023]
Abstract
Our chemical syntheses and related scientific investigations of natural products with complex architectures and powerful biological activities are described, focusing on the very large 3 nm-long polycyclic ethers called the ciguatoxins, highly strained and labile chromoprotein antitumor antibiotics featuring nine-membered enediyne cores, and extremely potent anthelmintic macrolides called the avermectins.
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Affiliation(s)
- Masahiro HIRAMA
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi, Japan
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Yamashita S, Takeuchi K, Koyama T, Inoue M, Hayashi Y, Hirama M. Practical route to the left wing of CTX1B and total syntheses of CTX1B and 54-deoxyCTX1B. Chemistry 2014; 21:2621-8. [PMID: 25529606 DOI: 10.1002/chem.201405629] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Indexed: 11/07/2022]
Abstract
Ciguatoxins, the principal causative agents of ciguatera seafood poisoning, are extremely large polycyclic ethers. We report herein a reliable route for constructing the left wing of CTX1B, which possesses the acid/base/oxidant-sensitive bisallylic ether moiety, by a 6-exo radical cyclization/ring-closing metathesis strategy. This new route enabled us to achieve the second-generation total synthesis of CTX1B and the first synthesis of 54-deoxyCTX1B.
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Affiliation(s)
- Shuji Yamashita
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan).
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Abstract
Maitotoxin holds a special place in the annals of natural products chemistry as the largest and most toxic secondary metabolite known to date. Its fascinating, ladder-like, polyether molecular structure and diverse spectrum of biological activities elicited keen interest from chemists and biologists who recognized its uniqueness and potential as a probe and inspiration for research in chemistry and biology. Synthetic studies in the area benefited from methodologies and strategies that were developed as part of chemical synthesis programs directed toward the total synthesis of some of the less complex members of the polyether marine biotoxin class, of which maitotoxin is the flagship. This account focuses on progress made in the authors' laboratories in the synthesis of large maitotoxin domains with emphasis on methodology development, strategy design, and structural comparisons of the synthesized molecules with the corresponding regions of the natural product. The article concludes with an overview of maitotoxin's biological profile and future perspectives.
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Affiliation(s)
- K. C. Nicolaou
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037 (USA), Fax: (+1) 858-784-2469, and Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093 (USA)
| | - Robert J. Aversa
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037 (USA), Fax: (+1) 858-784-2469, and Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093 (USA)
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Ishihara Y, Miyazaki K, Yamashita S, Hirama M. Remarkable Selectivity in Derivatization and Protection of Hydroxy Groups of 51-hydroxyCTX3C: Chemoselective Synthesis of Biotin-conjugated Ciguatoxin Derivatives. CHEM LETT 2009. [DOI: 10.1246/cl.2009.886] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Abstract
The last one hundred years have witnessed a dramatic increase in the power and reach of total synthesis. The pantheon of accomplishments in the field includes the total synthesis of molecules of unimaginable beauty and diversity such as the four discussed in this article: endiandric acids (1982), calicheamicin gamma(1)(I) (1992), Taxol (1994), and brevetoxin B (1995). Chosen from the collection of the molecules synthesized in the author's laboratories, these structures are but a small fraction of the myriad constructed in laboratories around the world over the last century. Their stories, and the background on which they were based, should serve to trace the evolution of the art of chemical synthesis to its present sharp condition, an emergence that occurred as a result of new theories and mechanistic insights, new reactions, new reagents and catalysts, and new synthetic technologies and strategies. Indeed, the advent of chemical synthesis as a whole must be considered as one of the most influential developments of the twentieth century in terms of its impact on society.
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Affiliation(s)
- K C Nicolaou
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
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Nicolaou K, Frederick M, Aversa R. Die Entdeckung und Synthese von marinen Polyethern. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200801696] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Sasaki M, Fuwa H. Convergent strategies for the total synthesis of polycyclic ether marine metabolites. Nat Prod Rep 2008; 25:401-26. [PMID: 18389143 DOI: 10.1039/b705664h] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Marine polycyclic ether natural products continue to fascinate chemists and biologists due to their exceptionally large and complex molecular architectures and potent and diverse biological activities. Tremendous progress has been made over the past decade toward the total synthesis of marine polycyclic ether natural products. In this area, a convergent strategy for assembling small fragments into an entire molecule always plays a key role in successful total synthesis. This review describes our efforts to develop convergent strategies for the synthesis of polycyclic ethers and their application to the total synthesis of gambierol, gymnocin-A, and brevenal, and to the partial synthesis of the central part of ciguatoxins and the nonacyclic polyether skeleton of gambieric acids.
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Affiliation(s)
- Makoto Sasaki
- Laboratory of Biostructural Chemistry, Graduate School of Life Sciences, Tohoku University, 1-1 Tsutsumidori-amamiya, Aoba-ku, Sendai 981-8555, Japan.
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Abstract
The unprecedented structure of the marine natural product brevetoxin B was elucidated by the research group of Nakanishi and Clardy in 1981. The ladderlike molecular architecture of this fused polyether molecule, its potent toxicity, and fascinating voltage-sensitive sodium channel based mechanism of action immediately captured the imagination of synthetic chemists. Synthetic endeavors resulted in numerous new methods and strategies for the construction of cyclic ethers, and culminated in several impressive total syntheses of this molecule and some of its equally challenging siblings. Of the marine polyethers, maitotoxin is not only the most complex and most toxic of the class, but is also the largest nonpolymeric natural product known to date. This Review begins with a brief history of the isolation of these biotoxins and highlights their biological properties and mechanism of action. Chemical syntheses are then described, with particular emphasis on new methods developed and applied to the total syntheses. The Review ends with a discussion of the, as yet unfinished, story of maitotoxin, and projects into the future of this area of research.
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Affiliation(s)
- K C Nicolaou
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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Inoue M, Miyazaki K, Ishihara Y, Tatami A, Ohnuma Y, Kawada Y, Komano K, Yamashita S, Lee N, Hirama M. Total synthesis of ciguatoxin and 51-hydroxyCTX3C. J Am Chem Soc 2007; 128:9352-4. [PMID: 16848469 DOI: 10.1021/ja063041p] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ciguatoxins, the principal causative toxins of ciguatera seafood poisoning, are large ladder-like polycyclic ethers with the 13 ether rings ranging from five- to nine-membered. In this paper, we describe the total synthesis of the two most toxic members of the ciguatoxin family, ciguatoxin 1 and 51-hydroxyCTX3C 2, based on a unified synthetic strategy. The key features in our syntheses were (i) direct construction of the O,S-acetal from the corresponding left and right wing fragments (3, 4, 14); (ii) stereo- and chemoselective radical reaction of the alpha-oxyradical with pentafluorophenyl acrylate to achieve cyclization of the seven-membered G-ring; (iii) ring-closing metathesis reaction to build the nine-membered F-ring; and (iv) an efficient protective group strategy using the oxidatively removable 2-naphthylmethyl groups.
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Affiliation(s)
- Masayuki Inoue
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
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Takizawa A, Fujiwara K, Doi E, Murai A, Kawai H, Suzuki T. Convergent synthesis of the common FGHI-ring part of ciguatoxins. Tetrahedron 2006. [DOI: 10.1016/j.tet.2006.05.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Hassfeld J, Kalesse M, Stellfeld T, Christmann M. Asymmetric total synthesis of complex marine natural products. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2005; 97:133-203. [PMID: 16261808 DOI: 10.1007/b135825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Among nature's ecosystems, the marine environment has been an extremely rich source of structurally complex and biologically active molecules. This review aims to cover the recent developments in the synthesis of marine natural products, also reflecting the trend of their increased use to address biological questions. The examples chosen should be viewed as representative of the different structural motifs on the one hand and the strategies and stimuli for their synthesis on the other.
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Affiliation(s)
- Jorma Hassfeld
- Institut für Organische Chemie, Universität Hannover, Schneiderberg 1B, 30167 Hannover, Germany
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Affiliation(s)
- Masayuki Inoue
- Department of Chemistry and Research and Analytical Center for Giant Molecules, Graduate School of Science, Tohoku University, Sendai, Japan.
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Hirama M. Total synthesis of ciguatoxin CTX3C: a venture into the problems of ciguatera seafood poisoning. CHEM REC 2005; 5:240-50. [PMID: 16059875 DOI: 10.1002/tcr.20049] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
After a twelve-year struggle, the total synthesis of ciguatoxin CTX3C has been achieved. Annually, more than 20,000 people worldwide suffer from ciguatera seafood poisoning. The extremely small amounts of the causative neurotoxin, ciguatoxin, in fish hampered the isolation, structural elucidation, detailed biological study, and preparation of anti-ciguatoxin antibodies for detecting these toxins. The large (3 nanometers long) and complicated molecular structure of ciguatoxins hindered chemists from completing a total synthesis. The chemical synthesis of CTX3C, determination of the absolute configuration, and synthesis-based preparation of the monoclonal antibodies as well as the effect of synthetic CTX3C on voltage-sensitive sodium channels are outlined.
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Affiliation(s)
- Masahiro Hirama
- Department of Chemistry, Graduate School of Science, Tohoku University, and SORST, Japan Science and Technology Corporation (JST), Sendai 980-8578, Japan.
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Synthesis of the EF-ring segment of ciguatoxin CTX1B based on novel regioselective reduction of unsaturated cyanohydrins and ring-closing olefin metathesis. Tetrahedron 2005. [DOI: 10.1016/j.tet.2005.05.073] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Herndon JW. The chemistry of the carbon-transition metal double and triple bond: annual survey covering the year 2003. Coord Chem Rev 2005. [DOI: 10.1016/j.ccr.2004.10.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Abstract
More than 20 000 people suffer annually from ciguatera seafood poisoning in subtropical and tropical regions. The extremely low content of the causative neurotoxins, designated as ciguatoxins, in fish has hampered their isolation, detailed biological study, and preparation of anti-ciguatoxin antibodies for detecting these toxins. Ciguatoxins consist of 12 trans-fused polycyclic ethers, ranging from six- to nine-membered, and include a spirally attached five-membered cyclic ether at one end. The large (3 nm in length) and complicated molecular structure of ciguatoxins has impeded chemists from completing their total synthesis. In 2001, we achieved the first total synthesis of ciguatoxin CTX3C by assembly of four structural fragments. Since then, protocols to combine the fragments have significantly improved in terms of overall stereoselectivity, efficiency, and practicality. In this Account, we describe recently evolved methodologies for the total synthesis of CTX3C.
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Affiliation(s)
- Masayuki Inoue
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
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Inoue M, Yamashita S, Tatami A, Miyazaki K, Hirama M. A new stereoselective synthesis of ciguatoxin right wing fragments. J Org Chem 2004; 69:2797-804. [PMID: 15074930 DOI: 10.1021/jo049877x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The right wings (13 and 14) of ciguatoxins were synthesized highly stereoselectively. Key transformations in the synthesis are (i) an oxiranyl anion strategy to attach the H ring, (ii) intramolecular carbonyl olefination to cyclize the J ring, (iii) regio- and stereoselective reduction of the epoxyacetal to install the C42-stereocenter, and (iv) stereoselective reductive etherification to construct the K ring. The present procedure greatly improved the stereoselectivity and efficiency in comparison to a previous synthesis. Remarkably, only 23 steps were required from monocyclic I ring 5 to construct the ciguatoxin right wings. The high practicality of the present synthesis ensures a sufficient supply of these complex fragments for total syntheses and biomedical applications.
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Affiliation(s)
- Masayuki Inoue
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
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Inoue M, Miyazaki K, Uehara H, Maruyama M, Hirama M. First- and second-generation total synthesis of ciguatoxin CTX3C. Proc Natl Acad Sci U S A 2004; 101:12013-8. [PMID: 15199182 PMCID: PMC514426 DOI: 10.1073/pnas.0401684101] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2004] [Accepted: 05/13/2004] [Indexed: 11/18/2022] Open
Abstract
More than 20,000 people suffer annually from ciguatera seafood poisoning in subtropical and tropical regions. The extremely low content of the causative neurotoxins, designated as ciguatoxins, in fish has hampered isolation, detailed biological studies, and preparation of anti-ciguatoxin antibodies for detecting these toxins. Furthermore, the large (3 nm in length) and complex molecular structure of ciguatoxins has impeded chemists from completing their total synthesis. In this article, the full details of studies leading to the total synthesis of ciguatoxin CTX3C are provided. The key elements of the first-generation approach include O,O-acetal formation from the right and left wing fragments, conversion from O,O-acetal to O,S-acetal, a radical reaction to cyclize the G ring, a ring-closing metathesis reaction to close the F ring, and final removal of the 2-naphtylmethyl protective groups. Subsequent studies provided a second-generation total synthesis, which is more concise and results in a higher yield. Second-generation synthesis was accomplished by using a direct method of constructing the key intermediate O,S-acetal from alpha-chlorosulfide and a secondary alcohol. These syntheses ensure a practical supply of ciguatoxin for biological applications.
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Affiliation(s)
- Masayuki Inoue
- Department of Chemistry, Graduate School of Science, Tohoku University and Solution Oriented Research for Science and Technology, Japan Science and Technology Agency, Sendai 980-8578, Japan
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Kobayashi S, Alizadeh BH, Sasaki SY, Oguri H, Hirama M. Synthesis of the Fully Functionalized ABCDE Ring Moiety of Ciguatoxin. Org Lett 2004; 6:751-4. [PMID: 14986966 DOI: 10.1021/ol0364475] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A fully functionalized ABCDE ring moiety of ciguatoxin (CTX), the major causative agent of ciguatera poisoning, was synthesized for the first time. The present strategy involves the efficient installation of the C5-dihydroxybutenyl substituent and construction of the tetrahydrooxepin E ring using a novel alpha-chlorosulfide synthon. [structure: see text]
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Affiliation(s)
- Shoji Kobayashi
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
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