1
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Watanabe T, Oga K, Matoba H, Nagatomo M, Inoue M. Total Synthesis of Taxol Enabled by Intermolecular Radical Coupling and Pd-Catalyzed Cyclization. J Am Chem Soc 2023; 145:25894-25902. [PMID: 37972241 DOI: 10.1021/jacs.3c10658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
Taxol (1) is a clinically used antineoplastic diterpenoid. The tetracyclic ring system comprises a 6/8/6-membered carbocycle (ABC-ring) and a fused oxetane ring (D-ring) embedded with a bridgehead double bond and decorated with multiple oxygen functionalities. Here, we report a convergent total synthesis of this exceedingly complex natural product. The C-ring fragment was designed to possess a bromocyclohexenone and an extra tetrahydrofuran ring to control the reactivity and selectivity, as well as to minimize functional group manipulations en route to 1. The α-alkoxyacyl telluride of the A-ring served as a radical precursor, and intermolecular radical coupling with the C-ring realized the installation of the C2- and C3-stereocenters and reductive removal of the bromide. After the C8-quaternary stereocenter was constructed by exploiting the three-dimensional shape of the intermediate, the C11-vinyl triflate of A-ring and the C8-methyl ketone of C-ring were utilized for Pd(0)-catalyzed cyclization of the central eight-membered B-ring with the bridgehead olefin. Adjustment of the oxidation level and attachment of the oxetane D-ring completed the total synthesis of 1 (28 steps, as the longest linear sequence). The fragment design principle and implementation of the powerful radical coupling reaction described in the present synthesis provide valuable information for planning and executing syntheses of diverse densely oxygenated terpenoids.
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Affiliation(s)
- Takahiro Watanabe
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo113-0033, Japan
| | - Kyohei Oga
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo113-0033, Japan
| | - Hiroaki Matoba
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo113-0033, Japan
| | - Masanori Nagatomo
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo113-0033, Japan
| | - Masayuki Inoue
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo113-0033, Japan
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2
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Gupta A, Laha JK. Growing Utilization of Radical Chemistry in the Synthesis of Pharmaceuticals. CHEM REC 2023; 23:e202300207. [PMID: 37565381 DOI: 10.1002/tcr.202300207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/19/2023] [Indexed: 08/12/2023]
Abstract
Our current unhealthy lifestyle and the exponential surge in the population getting affected by a variety of diseases have made pharmaceuticals or drugs an imperative part of life, making the development of innovative strategies for drug discovery or the introduction of refined, cost-effective and modern technologies for the synthesis of clinically used drugs, a need of the hour. Ever since their discovery, free radicals and radical cations or anions as reactive intermediates have captivated the chemists, resulting in an exceptional utilization of these moieties throughout the field of chemical synthesis, owing to their unprecedented and widespread reactivity. Sticking with the idea of not judging the book by its cover, despite the conventional thought process of radicals being unstable and difficult to control entities, scientists and academicians around the globe have done an appreciable amount of work utilizing both persistent as well as transient radicals for a variety of organic transformations, exemplifying them with the synthesis of significant biologically active pharmaceutical ingredients. This review truly accounts for the organic radical transformations including radical addition, radical cascade cyclization, radical/radical cross-coupling, coupling with metal-complexes and radical cations coupling with nucleophiles, that offers fascinating and unconventional approaches towards the construction of intricate structural frameworks of marketed APIs with high atom- and step-economy; complementing the otherwise employed traditional methods. This tutorial review presents a comprehensive package of diverse methods utilized for radical generation, featuring their reactivity to form critical bonds in pharmaceutical total synthesis or in building key starting materials or intermediates of their synthetic journey, acknowledging their excellence, downsides and underlying mechanisms, which are otherwise poorly highlighted in the literature. Despite great achievements over the past few decades in this area, many challenges and obstacles are yet to be unraveled to shorten the distance between the academics and the industry, which are all discussed in summary and outlook.
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Affiliation(s)
- Anjali Gupta
- Department of Pharmaceutical Technology (Process Chemistry), National Institute of Pharmaceutical Education & Research (NIPER) S.A.S. Nagar, Sahibzada Ajit Singh Nagar, Mohali, 160062, India
| | - Joydev K Laha
- Department of Pharmaceutical Technology (Process Chemistry), National Institute of Pharmaceutical Education & Research (NIPER) S.A.S. Nagar, Sahibzada Ajit Singh Nagar, Mohali, 160062, India
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3
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Wang X, Yin G, Wang Y, Zeng Y, Peng Y, Zhang X, Peng X, Wang Z. Asymmetric Total Synthesis of Four Stemona Alkaloids. Org Lett 2023; 25:2213-2217. [PMID: 36966439 DOI: 10.1021/acs.orglett.3c00349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/27/2023]
Abstract
Asymmetric total syntheses of four Stemona alkaloids were accomplished, and among them, bisdehydrostemoninine A and stemoninine A were synthesized for the first time. Notably, these four alkaloids were divergently synthesized from a common tetracyclic intermediate, which was easily obtained from a known compound. Friedel-Crafts acylation was employed to introduce the key side chain at position C3 of Stemona alkaloids.
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Affiliation(s)
- Xiaodong Wang
- School of Pharmacy, Lanzhou University, No. 199 West Donggang Road, Lanzhou 730000, Gansu, China
| | - Gaofeng Yin
- School of Pharmacy, Lanzhou University, No. 199 West Donggang Road, Lanzhou 730000, Gansu, China
| | - Yuqing Wang
- School of Pharmacy, Lanzhou University, No. 199 West Donggang Road, Lanzhou 730000, Gansu, China
| | - Yaofu Zeng
- School of Pharmaceutical Science, Hengyang Medical School, University of South China, Hengyang 421001, Hunan, China
| | - Ying Peng
- School of Pharmaceutical Science, Hengyang Medical School, University of South China, Hengyang 421001, Hunan, China
| | - Xi Zhang
- School of Pharmaceutical Science, Hengyang Medical School, University of South China, Hengyang 421001, Hunan, China
| | - Xue Peng
- School of Pharmaceutical Science, Hengyang Medical School, University of South China, Hengyang 421001, Hunan, China
| | - Zhen Wang
- School of Pharmaceutical Science, Hengyang Medical School, University of South China, Hengyang 421001, Hunan, China
- School of Pharmacy, Lanzhou University, No. 199 West Donggang Road, Lanzhou 730000, Gansu, China
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4
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Min L, Han JC, Zhang W, Gu CC, Zou YP, Li CC. Strategies and Lessons Learned from Total Synthesis of Taxol. Chem Rev 2023; 123:4934-4971. [PMID: 36917457 DOI: 10.1021/acs.chemrev.2c00763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/15/2023]
Abstract
Taxol (paclitaxel), the most well-known taxane diterpenoid, is the best-selling natural-source anticancer drug ever produced and one of the most common prescriptions in the treatment of breast, lung, and ovarian cancers, saving countless lives around the world. Structurally, Taxol possesses a highly oxygenated [6-8-6-4] core bearing 11 stereocenters, seven of which are contiguous chiral centers. Moreover, the extremely strained bicyclo[5.3.1] undecane ring system with a bridgehead double bond is a unique structural feature. All these features make Taxol a highly challenging synthetic target. Tremendous synthetic efforts from more than 60 research groups around the world have already culminated in ten total syntheses and three formal syntheses, as well as more than 60 synthetic model studies of Taxol. This review is intended to provide a long-overdue appraisal of the great achievements in the total syntheses of Taxol reported in the last few decades. In doing so, we summarize the development of synthesis toward Taxol from 1994 to 2022, including the evolution of synthetic strategy for accessing this complex molecular scaffold and key lessons learned from such endeavors. Finally, we briefly discuss the future of the research in this area.
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Affiliation(s)
- Long Min
- Shenzhen Grubbs Institute and Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Jing-Chun Han
- Shenzhen Grubbs Institute and Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Wen Zhang
- Shenzhen Grubbs Institute and Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Chen-Chen Gu
- Shenzhen Grubbs Institute and Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Yun-Peng Zou
- Shenzhen Grubbs Institute and Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Chuang-Chuang Li
- Shenzhen Grubbs Institute and Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China.,Shenzhen Bay Laboratory, Shenzhen 518132, China
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5
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Imamura Y, Takaoka K, Komori Y, Nagatomo M, Inoue M. Total Synthesis of Taxol Enabled by Inter- and Intramolecular Radical Coupling Reactions. Angew Chem Int Ed Engl 2023; 62:e202219114. [PMID: 36646637 DOI: 10.1002/anie.202219114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 01/14/2023] [Accepted: 01/16/2023] [Indexed: 01/18/2023]
Abstract
Taxol is a clinically used drug for the treatment of various types of cancers. Its 6/8/6/4-membered ring (ABCD-ring) system is substituted by eight oxygen functional groups and flanked by four acyl groups, including a β-amino acid side chain. Here we report a 34-step total synthesis of this unusually oxygenated and intricately fused structure. Inter- and intramolecular radical coupling reactions connected the A- and C-ring fragments and cyclized the B-ring, respectively. Functional groups of the A- and C-rings were then efficiently decorated by employing newly developed chemo-, regio-, and stereoselective reactions. Finally, construction of the D-ring and conjugation with the β-amino acid delivered taxol. The powerful coupling reactions and functional group manipulations implemented in the present synthesis provide new valuable information for designing multistep target-oriented syntheses of diverse bioactive natural products.
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Affiliation(s)
- Yusuke Imamura
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Kyohei Takaoka
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Yuma Komori
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Masanori Nagatomo
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Masayuki Inoue
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
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6
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Li Z, Zheng J, Li WDZ. Diverse strategic approaches en route to Taxol total synthesis. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2022.04.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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7
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Iiyama S, Fukaya K, Yamaguchi Y, Watanabe A, Yamamoto H, Mochizuki S, Saio R, Noguchi T, Oishi T, Sato T, Chida N. Total Synthesis of Paclitaxel. Org Lett 2022; 24:202-206. [PMID: 34904840 DOI: 10.1021/acs.orglett.1c03851] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The total synthesis of paclitaxel (Taxol) is described. Double Rubottom oxidation of the bis(silyl enol ether) derived from a tricarbocyclic diketone effectively installed a bridgehead olefin and C-5/C-13 hydroxy groups in a one-step operation. The novel Ag-promoted oxetane formation smoothly constructed the tetracyclic framework of paclitaxel.
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Affiliation(s)
- Shota Iiyama
- Department Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Keisuke Fukaya
- Department Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Yu Yamaguchi
- Department Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Ami Watanabe
- Department Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Hiroaki Yamamoto
- Department Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Shota Mochizuki
- Department Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Ryosuke Saio
- Department Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Takashi Noguchi
- Department Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Takeshi Oishi
- School of Medicine, Keio University, 4-1-1 Hiyoshi, Kohoku-ku, Yokohama 223-8521, Japan
| | - Takaaki Sato
- Department Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Noritaka Chida
- Department Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
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8
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Li JZ, Zhang WK, Ge GP, Zheng H, Wei WT. Recent progress in the radical α-C(sp 3)-H functionalization of ketones. Org Biomol Chem 2021; 19:7333-7347. [PMID: 34612358 DOI: 10.1039/d1ob01408k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The direct use structurally simple ketones as α-ketone radical sources for α-C(sp3)-H functionalization is a sustainable and powerful approach for constructing complex and multifunctional chemical scaffolds with diverse applications. The reactions of α-ketone radicals with alkenes, alkynes, enynes, imides, and imidazo[1,2-a]pyridines have broadened the structural diversity and complexity of ketones. Through chosen illustrative examples, we outline the recent progress in the development of methods that enable the radical α-C(sp3)-H functionalization of ketones, with an emphasis on radical initiation systems and possible mechanisms of the transformations. The application of these strategies is illustrated by the synthesis of several biologically active molecules and drug molecules. Further subdivision is based on substrate type and reaction type.
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Affiliation(s)
- Jiao-Zhe Li
- Key Laboratory of Advanced Mass Spectrometry and Molecular Analysis of Zhejiang Province, State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, School of Materials Science and Chemical Engineering, Ningbo University, Ningbo, Zhejiang 315211, China.
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9
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Nagatomo M, Inoue M. Convergent Assembly of Highly Oxygenated Natural Products Enabled by Intermolecular Radical Reactions. Acc Chem Res 2021; 54:595-604. [PMID: 33406830 DOI: 10.1021/acs.accounts.0c00792] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Natural products with a high ratio of sp3-hybridized atoms and oxygen-substituted stereogenic centers represent privileged structures for the development of pharmaceuticals and chemical probes. The multiple oxygen functionalities of these natural products endow their potent and selective biological activities, although they significantly heighten the challenge of their chemical assemblies. We focused on developing efficient strategies for the total syntheses of this biologically and chemically important class of molecules. A convergent strategy is more advantageous than a linear strategy for designing a shorter synthetic route because a convergent strategy enables direct coupling of functionalized fragments whereas a linear strategy involves stepwise construction of a molecule from its terminus. Radical reactions are preferred over polar reactions for the coupling of heavily functionalized and sp3-rich fragments, as they allow for C(sp3)-C(sp3) coupling without damaging diverse polar functional groups. With these considerations in mind, we designed radical-based convergent strategies for assembling highly oxygenated natural products. Here we summarize the concise total syntheses of asimicin (1, antibiotic activity), 1-hydroxytaxinine (2, cytotoxicity), polyoxins (3, antifungal activity), and hikizimycin (4, anthelmintic activity) as representative examples. Retrosynthetic disconnection at the central part of these molecules produces highly substituted α-alkoxy radicals as synthons. In the synthetic direction, the α-alkoxy radicals were generated from the corresponding α-alkoxyacyl tellurides in a unified fashion, and then utilized for four distinct coupling reactions. Formation of the Et radical from Et3B and O2 homolytically cleaves the C-Te bond of α-alkoxyacyl telluride, and the facile expulsion of carbon monoxide from the acyl radical leads to the α-alkoxy radical. Dimerization of the stabilized α-alkoxy radical resulted in the core structure of 1 with 10 contiguous stereocenters. The coupling adduct was derivatized to 1 through the attachment of two different carbon chains (17 steps as the longest linear sequence). Alternatively, intermolecular addition reactions of the α-alkoxy radicals to electron-deficient C═C, C═N, and C═O bonds, followed by Et3B-mediated radical termination, led to the core structures of 2, 3, and 4, respectively. Intermolecular coupling between the α-alkoxy radical and the cyclohexenone derivative and intramolecular pinacol coupling gave rise to the 6/8/6-fused ring system of 2, which was transformed to 2 (26 steps). The two amino acid moieties of 3 were prepared by combining the α-alkoxy radical and the oxime and were then condensed to complete the synthesis of 3 (11 steps). Furthermore, a combination of α-alkoxyacyl telluride and Et3B/O2 realized a novel addition reaction of α-alkoxy radicals to aldehydes. This method was incorporated in the construction of the core 4-amino-5-deoxyundecose with 10 contiguous stereocenters, which was fabricated with two appendage structures to deliver 4. The four total syntheses described here demonstrate the versatility and robustness of intermolecular radical reactions. These syntheses will also provide new insights for retrosynthetic analyses in the field of organic chemistry and streamline synthetic routes to various bioactive natural products with multiple oxygen functionalities.
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Affiliation(s)
- Masanori Nagatomo
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Masayuki Inoue
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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10
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Shirakata H, Nishiwaki H, Yamauchi S. Syntheses of all eight stereoisomers of conidendrin. Biosci Biotechnol Biochem 2020; 84:1986-1996. [PMID: 32552421 DOI: 10.1080/09168451.2020.1777081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
All eight stereoisomers of conidendrin were synthesized from (1 R,2 S,3 S)-1-(4-benzyloxy-3-methoxyphenyl)-3-(4-benzyloxy-3-methoxybenzyl)-2- hydroxymethyl-1,4-butanediol ((+)-4) and its enantiomer with high optical purity. The configurations at 4-positions of the conidendrin stereoisomers were constructed by intramolecular Friedel-Crafts reaction of protected 4. After conversion to tetrahydronaphthalene intermediate 7a, the 2- and 3-position of tetrahydronaphthalene structure 7a were converted to 3a- and 9a-position of (+)-α-conidendrin (3a), respectively. By the epimerization process of 2- or 3-position of 7a, the other diastereomers were obtained. All enantiomers were also synthesized from (-)-4.
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Affiliation(s)
- Hinako Shirakata
- Graduate School of Agriculture, Ehime University , Matsuyama, Japan
| | | | - Satoshi Yamauchi
- Graduate School of Agriculture, Ehime University , Matsuyama, Japan
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11
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Kuwana D, Nagatomo M, Inoue M. Total Synthesis of 5-epi-Eudesm-4(15)-ene-1β,6β-diol via Decarbonylative Radical Coupling Reaction. Org Lett 2019; 21:7619-7623. [DOI: 10.1021/acs.orglett.9b02895] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Daiki Kuwana
- Graduate School of Pharmaceutical Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Masanori Nagatomo
- Graduate School of Pharmaceutical Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Masayuki Inoue
- Graduate School of Pharmaceutical Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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12
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Imamura Y, Yoshioka S, Nagatomo M, Inoue M. Total Synthesis of 1-Hydroxytaxinine. Angew Chem Int Ed Engl 2019; 58:12159-12163. [PMID: 31211483 DOI: 10.1002/anie.201906872] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Indexed: 12/18/2022]
Abstract
1-Hydroxytaxinine (1) is a cytotoxic taxane diterpenoid. Its central eight-membered B-ring possesses four oxygen-functionalized centers (C1, C2, C9, and C10) and two quaternary carbon centers (C8 and C15), and is fused with six-membered A- and C-rings. The densely functionalized and intricately fused structure of 1 makes it a highly challenging synthetic target. Reported here is an efficient radical-based strategy for assembling 1 from A- and C-ring fragments. The A-ring bearing an α-alkoxyacyl telluride moiety underwent intermolecular coupling with the C-ring fragment by a Et3 B/O2 -promoted decarbonylative radical formation. After construction of the C8-quaternary stereocenter, a pinacol coupling reaction using a low-valent titanium reagent formed the B-ring with stereoselective installation of the C1,C2-diol. Subsequent manipulations at the A- and C-rings furnished 1 in 26 total steps.
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Affiliation(s)
- Yusuke Imamura
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Shun Yoshioka
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Masanori Nagatomo
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Masayuki Inoue
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
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13
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Imamura Y, Yoshioka S, Nagatomo M, Inoue M. Total Synthesis of 1‐Hydroxytaxinine. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201906872] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Yusuke Imamura
- Graduate School of Pharmaceutical SciencesThe University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-0033 Japan
| | - Shun Yoshioka
- Graduate School of Pharmaceutical SciencesThe University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-0033 Japan
| | - Masanori Nagatomo
- Graduate School of Pharmaceutical SciencesThe University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-0033 Japan
| | - Masayuki Inoue
- Graduate School of Pharmaceutical SciencesThe University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-0033 Japan
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