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α-Functionally Substituted α,β-Unsaturated Aldehydes as Fine Chemicals Reagents: Synthesis and Application. Molecules 2021; 26:molecules26144297. [PMID: 34299572 PMCID: PMC8306155 DOI: 10.3390/molecules26144297] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/12/2021] [Accepted: 07/14/2021] [Indexed: 11/16/2022] Open
Abstract
α-Functionalized α,β-unsaturated aldehydes is an important class of compounds, which are widely used in fine organic synthesis, biology, medicine and pharmacology, chemical industry, and agriculture. Some of the 2-substituted 2-alkenals are found to be the key metabolites in plant and animal cells. Therefore, the development of efficient methods for their synthesis attracts the attention of organic chemists. This review focusses on the recent advances in the synthesis of 2-functionally substituted 2-alkenals. The approaches to the preparation of α-alkyl α,β-unsaturated aldehydes are not included in this review.
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2
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Ohta M, Kato S, Sugai T, Fuwa H. Cobalt-Catalyzed Hartung-Mukaiyama Cyclization of γ-Hydroxy Olefins: Stereocontrolled Synthesis of the Tetrahydrofuran Moiety of Amphidinolide N. J Org Chem 2021; 86:5584-5615. [PMID: 33769047 DOI: 10.1021/acs.joc.1c00085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Cobalt-catalyzed Mukaiyama-type cyclization of γ-hydroxy olefins is known as an atom- and step-economical means for stereoselective synthesis of 2,5-trans-substituted tetrahydrofuran derivatives. In this study, we investigated the synthesis of a series of 2,5-substituted tetrahydrofuran derivatives by means of a cobalt-catalyzed Hartung-Mukaiyama cyclization. The stereochemical consequence of the reaction was found to be largely dependent on the substitution pattern and relative configuration of γ-hydroxy olefins. 2,5-cis-Substituted tetrahydrofuran derivatives could be obtained diastereoselectively from appropriately substituted γ-hydroxy olefins. Additionally, relatively bulky olefin substituents and unprotected hydroxy groups at non-interfering positions (e.g., α and δ) were well tolerated in the reaction. Finally, the synthetic versatility of the Hartung-Mukaiyama cyclization was demonstrated through a stereocontrolled synthesis of the tetrahydrofuran moiety of amphidinolide N, a potent cytotoxic macrolide of marine origin. This study expands the capacity of Mukaiyama-type cyclization in that it can be used in convergent assembly of complex tetrahydrofuran motifs from internal olefins.
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Affiliation(s)
- Masaki Ohta
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
| | - Shota Kato
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
| | - Tomoya Sugai
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
| | - Haruhiko Fuwa
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
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3
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Wang TC, Fan LF, Shen Y, Wang PS, Gong LZ. Asymmetric Allylic C–H Alkylation of Allyl Ethers with 2-Acylimidazoles. J Am Chem Soc 2019; 141:10616-10620. [DOI: 10.1021/jacs.9b05247] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Tian-Ci Wang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Lian-Feng Fan
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Yang Shen
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Pu-Sheng Wang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Liu-Zhu Gong
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
- Center for Excellence in Molecular Synthesis of CAS, Hefei 230026, China
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4
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Trost BM, Bai WJ, Stivala CE, Hohn C, Poock C, Heinrich M, Xu S, Rey J. Enantioselective Synthesis of des-Epoxy-Amphidinolide N. J Am Chem Soc 2018; 140:17316-17326. [DOI: 10.1021/jacs.8b11827] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Barry M. Trost
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States
| | - Wen-Ju Bai
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States
| | - Craig E. Stivala
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States
| | - Christoph Hohn
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States
| | - Caroline Poock
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States
| | - Marc Heinrich
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States
| | - Shiyan Xu
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States
| | - Jullien Rey
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States
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5
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Liao S, Porta A, Cheng X, Ma X, Zanoni G, Zhang L. Bifunctional Ligand Enables Efficient Gold-Catalyzed Hydroalkenylation of Propargylic Alcohol. Angew Chem Int Ed Engl 2018; 57:8250-8254. [PMID: 29704310 PMCID: PMC6592274 DOI: 10.1002/anie.201802533] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 04/23/2018] [Indexed: 11/10/2022]
Abstract
Using the previously designed biphenyl-2-ylphosphine ligand, featuring a remote tertiary amino group, the first gold-catalyzed intermolecular hydroalkenylation of alkynes has been developed. Synthetically valuable conjugated dienyl alcohols are formed in moderate to good yields. A range of alkenyltrifluoroborates are allowed as the alkenyl donor, and no erosion of alkene geometry and/or the propargylic configuration are detected. DFT calculations confirm the critical role of the remote basic group in the ligand as a general-base catalyst for promoting this novel gold catalysis with good efficiency.
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Affiliation(s)
- Shengrong Liao
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, CAS, Guangzhou, P. R. China
- Department of Chemistry and Biochemistry, UCSB, Santa Barbara, CA, 93106, USA
| | - Alessio Porta
- Dept of Chem., Univ. of Pavia, Viale Taramelli, 10, 27100, Pavia, Italy
| | - Xinpeng Cheng
- Department of Chemistry and Biochemistry, UCSB, Santa Barbara, CA, 93106, USA
| | - Xu Ma
- Department of Chemistry and Biochemistry, UCSB, Santa Barbara, CA, 93106, USA
| | - Giuseppe Zanoni
- Dept of Chem., Univ. of Pavia, Viale Taramelli, 10, 27100, Pavia, Italy
| | - Liming Zhang
- Department of Chemistry and Biochemistry, UCSB, Santa Barbara, CA, 93106, USA
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6
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Ando H, Kimishima A, Ohara M, Hirose T, Matsumaru T, Takada H, Morodome K, Miyamoto T, Sugawara A, Ōmura S, Sunazuka T. Toward the total synthesis of luminamicin; an anaerobic antibiotic: construction of highly functionalized cis-decalin containing a bridged ether moiety. J Antibiot (Tokyo) 2017; 71:268-272. [PMID: 28676718 DOI: 10.1038/ja.2017.77] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 05/25/2017] [Accepted: 05/26/2017] [Indexed: 11/09/2022]
Abstract
Synthesis of a cis-decalin moiety, containing an oxa-bridged cis-decalin ring system (11-oxatricyclo(5.3.1.1,703,8)undecane), as a key intermediate of the total synthesis of luminamicin (1) was accomplished. One of the essential steps in our synthetic route is construction of a cis-decaline framework using a one-pot Michael addition-aldol reaction. Additionally, the bridged ether moiety was obtained by an intramolecular 1,6-oxa-Michael reaction of a conjugated aldehyde.
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Affiliation(s)
- Hiroyasu Ando
- Graduate School of Infection Control Sciences and Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan
| | - Aoi Kimishima
- Graduate School of Infection Control Sciences and Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan
| | - Motoyoshi Ohara
- Graduate School of Infection Control Sciences and Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan
| | - Tomoyasu Hirose
- Graduate School of Infection Control Sciences and Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan
| | - Takanori Matsumaru
- Graduate School of Infection Control Sciences and Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan
| | - Hirokazu Takada
- Graduate School of Infection Control Sciences and Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan
| | - Keisuke Morodome
- Graduate School of Infection Control Sciences and Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan
| | - Takehiro Miyamoto
- Graduate School of Infection Control Sciences and Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan
| | - Akihiro Sugawara
- Graduate School of Infection Control Sciences and Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan
| | - Satoshi Ōmura
- Graduate School of Infection Control Sciences and Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan
| | - Toshiaki Sunazuka
- Graduate School of Infection Control Sciences and Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan
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7
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Klenk S, Rupf S, Suntrup L, van der Meer M, Sarkar B. The Power of Ferrocene, Mesoionic Carbenes, and Gold: Redox-Switchable Catalysis. Organometallics 2017. [DOI: 10.1021/acs.organomet.7b00270] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Sinja Klenk
- Institut für Chemie
und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, D-14195 Berlin, Germany
| | - Susanne Rupf
- Institut für Chemie
und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, D-14195 Berlin, Germany
| | - Lisa Suntrup
- Institut für Chemie
und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, D-14195 Berlin, Germany
| | - Margarethe van der Meer
- Institut für Chemie
und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, D-14195 Berlin, Germany
| | - Biprajit Sarkar
- Institut für Chemie
und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, D-14195 Berlin, Germany
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8
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Yu L, Wang H, Akhmedov NG, Sowa C, Liu K, Kim H, Williams L. Direct Entry to 4,10-Didesmethyl (9S)-Dihydroerythronolide A via Catalytic Allene Osmylation. Org Lett 2016; 18:2868-71. [DOI: 10.1021/acs.orglett.6b01151] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Libing Yu
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Huan Wang
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Novruz G. Akhmedov
- Department
of Chemistry, West Virginia University, 406 Clark Hall, Prospect Street, Morgantown, West Virginia 26506, United States
| | - Christopher Sowa
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Kai Liu
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Hiyun Kim
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Lawrence Williams
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
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9
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Kawashima Y, Toyoshima A, Fuwa H, Sasaki M. Toward the Total Synthesis of Amphidinolide N: Synthesis of the C8–C29 Fragment. Org Lett 2016; 18:2232-5. [DOI: 10.1021/acs.orglett.6b00871] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yuki Kawashima
- Graduate School of Life Sciences, Tohoku University, 2-1-1
Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Atsushi Toyoshima
- Graduate School of Life Sciences, Tohoku University, 2-1-1
Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Haruhiko Fuwa
- Graduate School of Life Sciences, Tohoku University, 2-1-1
Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Makoto Sasaki
- Graduate School of Life Sciences, Tohoku University, 2-1-1
Katahira, Aoba-ku, Sendai 980-8577, Japan
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10
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Swick SM, Schaefer SL, O’Neil GW. Synthesis of the C 1-C 17 fragment of the archazolids by complex cis-homodimer cross metathesis. Tetrahedron Lett 2015; 56:4039-4042. [PMID: 26257444 PMCID: PMC4525707 DOI: 10.1016/j.tetlet.2015.05.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A synthesis of the C1-C17 fragment of the archazolids is described featuring a complex cross-metathesis coupling reaction between a cis-homodimer (prepared by silyl-tethered ring-closing metathesis) and the Z,Z-terminal triene containing "eastern domain" of the archazolid natural products. This cross-metathesis was only successful when using the cis- as opposed to the monomer or trans-homodimer, with the cis-dimer added batchwise to minimize cis/trans-isomerization. The product was obtained in an optimized 78% yield using the Hoveyda-Grubbs catalyst at 50 °C in toluene.
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Affiliation(s)
- Steven M. Swick
- Department of Chemistry, Western Washington University, Bellingham, WA, 98225, USA
| | - Sara L. Schaefer
- Department of Chemistry, Western Washington University, Bellingham, WA, 98225, USA
| | - Gregory W. O’Neil
- Department of Chemistry, Western Washington University, Bellingham, WA, 98225, USA
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11
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Mahapatra S, Carter RG. Exploiting hidden symmetry in natural products: total syntheses of amphidinolides C and F. J Am Chem Soc 2013; 135:10792-803. [PMID: 23845005 PMCID: PMC3786714 DOI: 10.1021/ja404796n] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The total synthesis of amphidinolide C and a second-generation synthesis of amphidinolide F have been accomplished through the use of a common intermediate to access both the C1-C8 and the C18-C25 sections. The development of a Ag-catalyzed cyclization of a propargyl benzoate diol is described to access both trans-tetrahydrofuran rings. The evolution of a Felkin-controlled, 2-lithio-1,3-dienyl addition strategy to incorporate C9-C11 diene as well as C8 stereocenter is detailed. Key controlling aspects in the sulfone alkylation/oxidative desulfurization to join the major subunits, including the exploration of the optimum masking group for the C18 carbonyl motif, are discussed. A Trost asymmetric alkynylation and a stereoselective cuprate addition to an alkynoate have been developed for the rapid construction of the C26-C34 subunit. A Tamura/Vedejs olefination to introduce the C26 side arm of amphidnolides C and F is employed. The late-stage incorporation of the C15, C18 diketone motif proved critical to the successful competition of the total syntheses.
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Affiliation(s)
- Subham Mahapatra
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
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12
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Lu L, Zhang W, Nam S, Horne DA, Jove R, Carter RG. Amphidinolide B: total synthesis, structural investigation, and biological evaluation. J Org Chem 2013; 78:2213-47. [PMID: 23406192 PMCID: PMC3631602 DOI: 10.1021/jo3026077] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The total syntheses of amphidinolide B1 and the proposed structure of amphidinolide B2 have been accomplished. Key aspects of this work include the development of a practical, non-transition-metal-mediated method for the construction of the C13-C15 diene, the identification of α-chelation and dipole minimization models for diastereoselective methyl ketone aldol reactions, the discovery of a spontaneous Horner-Wadsworth-Emmons macrocyclization strategy, and the development of a novel late stage method for construction of an allylic epoxide moiety. The originally proposed structure for amphidinolide B2 and diastereomers thereof display potent antitumor activities with IC50 values ranging from 3.3 to 94.5 nM against human solid and blood tumor cells. Of the different stereoisomers, the proposed structure of amphidinolide B2 is over 12-fold more potent than the C8,9-epimer and C18-epimer in human DU145 prostate cancer cells. These data suggest that the epoxide stereochemistry is a significant factor for anticancer activity.
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Affiliation(s)
- Liang Lu
- Department of Chemistry, Oregon State University, Corvallis, OR 97331
| | - Wei Zhang
- Department of Chemistry, Oregon State University, Corvallis, OR 97331
| | - Sangkil Nam
- Department of Molecular Medicine, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA
| | - David A. Horne
- Department of Molecular Medicine, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA
| | - Richard Jove
- Department of Molecular Medicine, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA
| | - Rich G. Carter
- Department of Chemistry, Oregon State University, Corvallis, OR 97331
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13
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Trost BM, Rey J. Diastereoselective formation of tetrahydrofurans via Pd-catalyzed asymmetric allylic alkylation: synthesis of the C13-C29 subunit of amphidinolide N. Org Lett 2012; 14:5632-5. [PMID: 23098131 DOI: 10.1021/ol302409g] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An efficient synthesis of the C13-C29 fragment of amphidinolide N is described. The synthesis relies on a new strategy involving Pd-catalyzed asymmetric allylic alkylation to generate diastereoselectively the cis- or trans-THF unit simply by varying the enantiomer of the ligand. The C19 hydroxyl-bearing stereocenter was introduced using a chelation-controlled allylation which led exclusively to a single diastereoisomer.
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Affiliation(s)
- Barry M Trost
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA.
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14
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Roy S, Spilling CD. Synthesis of the C(18)-C(34) fragment of amphidinolide C and the C(18)-C(29) fragment of amphidinolide F. Org Lett 2010; 12:5326-9. [PMID: 21028791 DOI: 10.1021/ol102345v] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A convergent synthesis of the C(18)-C(34) fragment of amphidinolide C and the C(18)-C(29) fragment of amphidinolide F is reported. The approach involves the synthesis of the common intermediate tetrahydrofuranyl-β-ketophosphonate via cross metathesis, Pd(0)-catalyzed cyclization, and hydroboration-oxidation. The β-ketophosphonate was coupled to three side chain aldehydes using a Horner-Wadsworth-Emmons (HWE) olefination reaction to give dienones, which were reduced with l-selectride to give the fragments of amphidinolide C and F.
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Affiliation(s)
- Sudeshna Roy
- Department of Chemistry and Biochemistry, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri 63121, United States
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15
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Nicolaou KC, Bulger PG, Brenzovich WE. Synthesis of iso-epoxy-amphidinolide N and des-epoxy-caribenolide I structures. Revised strategy and final stages. Org Biomol Chem 2006; 4:2158-83. [PMID: 16729127 DOI: 10.1039/b602021f] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A general and highly convergent synthetic route to the macrocyclic core structures of the antitumour agents amphidinolide N (1) and caribenolide I (2) has been developed, and the total synthesis of iso-epoxy-amphidinolide N and des-epoxy-caribenolide I structures is described. Central to the revised strategy was the use of a Horner-Wadsworth-Emmons olefination between beta-ketophosphonate 51 and aldehyde 14 to construct the C1-C13 sector common to both 1 and 2. Stereoselective alkylation of hydrazone 11 with iodide 65 and then with bromide 56 allowed for the rapid assembly of the complete caribenolide I carbon skeleton. Key steps in the completion of the synthesis of des-epoxy-caribenolide I structure 78 included hydrolysis of a sensitive methyl ester using Me(3)SnOH, followed by regioselective macrolactonisation of the resulting diol seco-acid and global deprotection. Coupling of hydrazone 11, bromide 56 and iodide 64 was followed by an analogous sequence of late-stage manoeuvres to arrive at the fully deprotected des-epoxy-amphidinolide N framework, obtained as a mixture of hemiacetal and bicyclic acetal 84. Regio- and diastereo-selective epoxidation of the C6 methylene group in bicyclic acetal 84 provided access to iso-epoxy-amphidinolide N stereoisomer 89.
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Affiliation(s)
- K C Nicolaou
- Department of Chemistry and Skaggs Institute for Chemical Biology, Scripps Research Institute, La Jolla, California 92037, USA.
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