1
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Boyd EA, Shin C, Charboneau DJ, Peters JC, Reisman SE. Reductive samarium (electro)catalysis enabled by Sm III-alkoxide protonolysis. Science 2024; 385:847-853. [PMID: 39172824 DOI: 10.1126/science.adp5777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Accepted: 07/23/2024] [Indexed: 08/24/2024]
Abstract
Samarium diiodide (SmI2) is a privileged, single-electron reductant deployed in diverse synthetic settings. However, generalizable methods for catalytic turnover remain elusive because of the well-known challenge associated with cleaving strong SmIII-O bonds. Prior efforts have focused on the use of highly reactive oxophiles to enable catalyst turnover. However, such approaches give rise to complex catalyst speciation and intrinsically limit the synthetic scope. Herein, we leveraged a mild and selective protonolysis strategy to achieve samarium-catalyzed, intermolecular reductive cross-coupling of ketones and acrylates with broad scope. The modularity of our approach allows rational control of selectivity based on solvent, pKa (where Ka is the acid dissociation constant), and the samarium coordination sphere and provides a basis for future developments in catalytic and electrocatalytic lanthanide chemistry.
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Affiliation(s)
- Emily A Boyd
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Chungkeun Shin
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - David J Charboneau
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Jonas C Peters
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Sarah E Reisman
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
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2
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Zhang Y, Chen L, Jia Y. Total Synthesis of Pallamolides A-E. Angew Chem Int Ed Engl 2024; 63:e202319127. [PMID: 38504637 DOI: 10.1002/anie.202319127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 03/12/2024] [Accepted: 03/19/2024] [Indexed: 03/21/2024]
Abstract
We have achieved the first total synthesis of pallamolides A-E. Of these compounds, pallamolides B-E possess intriguing tetracyclic skeletons with novel intramolecular transesterifications. Key transformations include highly diastereoselective sequential Michael addition reactions to construct the bicyclo[2.2.2]octane core with the simultaneous generation of two quaternary carbon centers, a one-pot SmI2-mediated intramolecular ketyl-enoate cyclization/ketone reduction to generate the key oxabicyclo[3.3.1]nonane moiety, and an acid-mediated deprotection/oxa-Michael addition/β-hydroxy elimination cascade sequence to assemble the tetracyclic pallamolide skeleton. Kinetic resolution of ketone 14 through Corey-Bakshi-Shibata reduction enabled the asymmetric synthesis of pallamolides A-E.
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Affiliation(s)
- Yu Zhang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, and Chemical Biology Center, Peking University, 38 Xueyuan Road, Beijing, 100191, P. R. China
| | - Lijun Chen
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, and Chemical Biology Center, Peking University, 38 Xueyuan Road, Beijing, 100191, P. R. China
| | - Yanxing Jia
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, and Chemical Biology Center, Peking University, 38 Xueyuan Road, Beijing, 100191, P. R. China
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3
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Classen M, Kicin B, Ruf VAP, Hamminger A, Ribadeau-Dumas L, Amberg WM, Carreira EM. Total Synthesis of (+)-Euphorikanin A via an Atropospecific Cascade. J Am Chem Soc 2023; 145:27225-27229. [PMID: 38051111 PMCID: PMC10739989 DOI: 10.1021/jacs.3c11000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 11/14/2023] [Accepted: 11/15/2023] [Indexed: 12/07/2023]
Abstract
A total synthesis of the ingenane-derived diterpenoid (+)-euphorikanin A is described. Key to the strategy is a stereocontrolled one-pot sequence consisting of transannular aldol addition reaction, hemiketal formation, and subsequent semipinacol rearrangement that efficiently leads to the complete euphorikanin skeleton. Atroposelective ring-closing olefin metathesis proved critical for the stereospecific cascade, leading to formation of a (Z)-bicyclo[7.4.1]tetradecenone core. An additional salient feature of the route is pyrolysis of a bis-methylxanthate to cleanly furnish the natural product.
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Affiliation(s)
| | | | | | - Alexander Hamminger
- Department of Chemistry and
Applied Biosciences, Laboratory of Organic Chemistry, ETH Zürich, 8093 Zürich, Switzerland
| | - Loélie Ribadeau-Dumas
- Department of Chemistry and
Applied Biosciences, Laboratory of Organic Chemistry, ETH Zürich, 8093 Zürich, Switzerland
| | - Willi M. Amberg
- Department of Chemistry and
Applied Biosciences, Laboratory of Organic Chemistry, ETH Zürich, 8093 Zürich, Switzerland
| | - Erick M. Carreira
- Department of Chemistry and
Applied Biosciences, Laboratory of Organic Chemistry, ETH Zürich, 8093 Zürich, Switzerland
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4
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Faul MM, Brummond KM. A Celebration of the Publication of the 100th Volume of Organic Syntheses. J Med Chem 2023; 66:15576-15579. [PMID: 37975593 DOI: 10.1021/acs.jmedchem.3c01994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Affiliation(s)
- Margaret M Faul
- Process Development, Amgen Inc., One Amgen Center Drive, Thousand Oaks, California 91320, United States
| | - Kay M Brummond
- University of Pittsburgh, Department of Chemistry, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
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5
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Faul MM, Brummond KM. A Celebration of the Publication of the 100th Volume of Organic Syntheses. ACS Med Chem Lett 2023; 14:1603-1606. [PMID: 38116439 PMCID: PMC10726450 DOI: 10.1021/acsmedchemlett.3c00485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Indexed: 12/21/2023] Open
Affiliation(s)
- Margaret M. Faul
- Process
Development, Amgen Inc., One Amgen Center Drive, Thousand Oaks, California 91320, United States
| | - Kay M. Brummond
- University
of Pittsburgh, Department of Chemistry, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
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6
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Faul MM, Brummond KM. A Celebration of the Publication of the 100th Volume of Organic Syntheses. Org Lett 2023; 25:8393-8396. [PMID: 37975612 DOI: 10.1021/acs.orglett.3c03569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Affiliation(s)
- Margaret M Faul
- Process Development, Amgen Inc., One Amgen Center Drive, Thousand Oaks, California 91320, United States
| | - Kay M Brummond
- University of Pittsburgh, Department of Chemistry, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
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7
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Faul MM, Brummond KM. A Celebration of the Publication of the 100th Volume of Organic Syntheses. J Org Chem 2023; 88:16043-16046. [PMID: 37975592 DOI: 10.1021/acs.joc.3c02424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Affiliation(s)
- Margaret M Faul
- Process Development, Amgen Inc., One Amgen Center Drive, Thousand Oaks, California 91320, United States
| | - Kay M Brummond
- University of Pittsburgh, Department of Chemistry, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
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8
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Faul MM, Brummond KM. A Celebration of the Publication of the 100th Volume of Organic Syntheses. J Am Chem Soc 2023; 145:25509-25512. [PMID: 37975579 DOI: 10.1021/jacs.3c12163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Affiliation(s)
- Margaret M Faul
- Process Development, Amgen Inc., One Amgen Center Drive, Thousand Oaks, California 91320, United States
| | - Kay M Brummond
- University of Pittsburgh, Department of Chemistry, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
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9
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Zhao W, Zhang D, Wang Y, Yang M. Total Syntheses of Rhodomollins A and B. J Am Chem Soc 2023. [PMID: 38016018 DOI: 10.1021/jacs.3c12249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2023]
Abstract
The first and asymmetric total syntheses of rhodomollins A and B, two rhodomollane type grayanoids featuring a d-homograyanane carbon skeleton and an oxa-bicyclo[3.2.1] core, were accomplished via a convergent strategy. A Stille coupling and a lithium-halogen exchange/intramolecular nucleophilic addition to the aldehyde sequence were employed to assemble two enantioenriched fragments. The oxa-bicyclo[3.2.1] core was achieved through an intramolecular SN2 substitution of cyclic sulfate of 1,2-diols (Williamson ether synthesis). The A ring oxidation states were adjusted by a Payne/Meinwald rearrangement sequence and subsequent redox transformations.
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Affiliation(s)
- Weizhao Zhao
- State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, 222 South Tianshui Road, Lanzhou, Gansu Province 730000, China
| | - Duo Zhang
- State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, 222 South Tianshui Road, Lanzhou, Gansu Province 730000, China
| | - Yuran Wang
- State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, 222 South Tianshui Road, Lanzhou, Gansu Province 730000, China
| | - Ming Yang
- State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, 222 South Tianshui Road, Lanzhou, Gansu Province 730000, China
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10
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Papidocha SM, Bulthaupt HH, Carreira EM. Synthesis of Neocaesalpin A, AA, and Nominal Neocaesalpin K. Angew Chem Int Ed Engl 2023; 62:e202310149. [PMID: 37681486 DOI: 10.1002/anie.202310149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 09/04/2023] [Accepted: 09/06/2023] [Indexed: 09/09/2023]
Abstract
The first total synthesis of heavily oxidized cassane-type diterpenoid neocaesalpin A (1) is disclosed. At the heart of the synthesis lies an intermolecular Diels-Alder reaction that rapidly assembles the target framework from commercial materials. A carefully orchestrated sequence of oxidations secured the desired oxygenation pattern. Late-stage release of the characteristic butenolide occurred through a novel mercury(II)-mediated furan oxidation. Successful extension of the route allowed preparation of neocaesalpin AA (2) as well as nominal neocaesalpin K (3) and suggested structural revision of neocaesalpin K, leading to the hypothesis that the two are likely the same natural product with correct assignment as 2.
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Affiliation(s)
- Sven M Papidocha
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, 8093, Zürich, Switzerland
| | - Hendrik H Bulthaupt
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, 8093, Zürich, Switzerland
| | - Erick M Carreira
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, 8093, Zürich, Switzerland
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11
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Mushtaq A, Zahoor AF. Mukaiyama aldol reaction: an effective asymmetric approach to access chiral natural products and their derivatives/analogues. RSC Adv 2023; 13:32975-33027. [PMID: 38025859 PMCID: PMC10631541 DOI: 10.1039/d3ra05058k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 10/21/2023] [Indexed: 12/01/2023] Open
Abstract
The Mukaiyama aldol reaction is generally a Lewis-acid catalyzed cross-aldol reaction between an aldehyde or ketone and silyl enol ether. It was first described by Mukaiyama in 1973, almost 5 decades ago, to achieve the enantioselective synthesis of β-hydroxy carbonyl compounds in high percentage yields. Mukaiyama aldol adducts play a pivotal role in the synthesis of various naturally occurring and medicinally important organic compounds such as polyketides, alkaloids, macrolides, etc. This review highlights the significance of the Mukaiyama aldol reaction towards the asymmetric synthesis of a wide range of biologically active natural products reported recently (since 2020).
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Affiliation(s)
- Aqsa Mushtaq
- Department of Chemistry, Government College University Faisalabad 38000 Faisalabad Pakistan
| | - Ameer Fawad Zahoor
- Department of Chemistry, Government College University Faisalabad 38000 Faisalabad Pakistan
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12
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Bulthaupt HH, Glatz F, Papidocha SM, Wu C, Teh S, Wolfrum S, Balážová L, Wolfrum C, Carreira EM. Enantioselective Total Syntheses of Cassane Furanoditerpenoids and Their Stimulation of Cellular Respiration in Brown Adipocytes. J Am Chem Soc 2023; 145:21562-21568. [PMID: 37751294 DOI: 10.1021/jacs.3c07597] [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: 09/27/2023]
Abstract
We report the first and enantioselective total syntheses of (+)-1-deacetylcaesalmin C, (+)-δ-caesalpin, (+)-norcaesalpinin MC, and (+)-norcaesalpinin P. Salient features of the synthetic strategy are an exo-selective intramolecular Diels-Alder reaction of a furanoquinone monoketal and subsequent chemoselective reduction of the resulting pentacyclic furfuryl ketal, furnishing a keystone intermediate. The latter enables access to the collection of natural products through implementation of stereoselective oxidations. Having accessed the cassane furanoditerpenoids, we unveil previously unknown bioactivity: (+)-1-deacetylcaesalmin C stimulates respiration in brown adipocytes, which has been suggested to play a central role in treatment of obesity.
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Affiliation(s)
| | - Fabian Glatz
- ETH Zurich, Vladimir-Prelog-Weg 3, HCI, 8093 Zurich, Switzerland
| | - Sven M Papidocha
- ETH Zurich, Vladimir-Prelog-Weg 3, HCI, 8093 Zurich, Switzerland
| | - Chunyan Wu
- ETH Zurich, Schorenstrasse 16, IFN, 8603 Schwerzenbach, Switzerland
| | - Shawn Teh
- ETH Zurich, Vladimir-Prelog-Weg 3, HCI, 8093 Zurich, Switzerland
| | - Susanne Wolfrum
- ETH Zurich, Vladimir-Prelog-Weg 3, HCI, 8093 Zurich, Switzerland
| | - Lucia Balážová
- Biomedical Research Center of the Slovak Academy of Sciences, 84505 Bratislava, Slovakia
| | | | - Erick M Carreira
- ETH Zurich, Vladimir-Prelog-Weg 3, HCI, 8093 Zurich, Switzerland
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13
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Ryckaert B, Demeyere E, Degroote F, Janssens H, Winne JM. 1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures. Beilstein J Org Chem 2023; 19:115-132. [PMID: 36761474 PMCID: PMC9907017 DOI: 10.3762/bjoc.19.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 01/20/2023] [Indexed: 02/05/2023] Open
Abstract
This review covers the synthetic applications of 1,4-dithianes, as well as derivatives thereof at various oxidation states. The selected examples show how the specific heterocyclic reactivity can be harnessed for the controlled synthesis of carbon-carbon bonds. The reactivity is compared to and put into context with more common synthetic building blocks, such as 1,3-dithianes and (hetero)aromatic building blocks. 1,4-Dithianes have as yet not been investigated to the same extent as their well-known 1,3-dithiane counterparts, but they do offer attractive transformations that can find good use in the assembly of a wide array of complex molecular architectures, ranging from lipids and carbohydrates to various carbocyclic scaffolds. This versatility arises from the possibility to chemoselectively cleave or reduce the sulfur-heterocycle to reveal a versatile C2-synthon.
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Affiliation(s)
- Bram Ryckaert
- Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 (S4), 9000 Gent, Belgium
| | - Ellen Demeyere
- Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 (S4), 9000 Gent, Belgium
| | - Frederick Degroote
- Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 (S4), 9000 Gent, Belgium
| | - Hilde Janssens
- Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 (S4), 9000 Gent, Belgium
| | - Johan M Winne
- Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 (S4), 9000 Gent, Belgium
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14
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Beller MP, Koert U. Vicinal ketoesters – key intermediates in the total synthesis of natural products. Beilstein J Org Chem 2022; 18:1236-1248. [PMID: 36158171 PMCID: PMC9490073 DOI: 10.3762/bjoc.18.129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 08/30/2022] [Indexed: 11/23/2022] Open
Abstract
This review summarizes examples for the application of vicinal ketoesters such as α-ketoesters, mesoxalic esters, and α,β-diketoesters as key intermediates in the total synthesis of natural products utilizing their electrophilic keto group as reactive site. Suitable key reactions are, e.g., aldol additions, carbonyl ene reactions, Mannich reactions, and additions of organometallic reagents. The vicinal arrangement of carbonyl groups allows the stabilization of reactive conformations by chelation or dipole control.
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Affiliation(s)
- Marc Paul Beller
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany
| | - Ulrich Koert
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany
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15
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Vasilev VH, Spessert L, Yu K, Maimone TJ. Total Synthesis of Resiniferatoxin. J Am Chem Soc 2022; 144:16332-16337. [PMID: 36043948 DOI: 10.1021/jacs.2c08200] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
From both structural and functional perspectives, the large family of daphnane diterpene orthoesters (DDOs) represent a truly remarkable class of natural products. As potent lead compounds for the treatment of pain, neurodegeneration, HIV/AIDS, and cancer, their medicinal potential continues to be heavily investigated, yet synthetic routes to DDO natural products remain rare. Herein we report a distinct approach to this class of complex diterpenes, highlighted by a 15-step total synthesis of the flagship DDO, resiniferatoxin.
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Affiliation(s)
- Vasil H Vasilev
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
| | - Lukas Spessert
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
| | - Kuan Yu
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
| | - Thomas J Maimone
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
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16
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Morrill C, Péter Á, Amalina I, Pye E, Crisenza GEM, Kaltsoyannis N, Procter DJ. Diastereoselective Radical 1,4-Ester Migration: Radical Cyclizations of Acyclic Esters with SmI 2. J Am Chem Soc 2022; 144:13946-13952. [PMID: 35858251 PMCID: PMC9377304 DOI: 10.1021/jacs.2c05972] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Reductive cyclizations of carbonyl compounds, mediated
by samarium(II)
diiodide (SmI2, Kagan’s reagent), represent an invaluable
platform to generate molecular complexity in a stereocontrolled manner.
In addition to classical ketone and aldehyde substrates, recent advances
in radical chemistry allow the cyclization of lactone and lactam-type
substrates using SmI2. In contrast, acyclic esters are
considered to be unreactive to SmI2 and their participation
in reductive cyclizations is unprecedented. Here, we report a diastereoselective
radical 1,4-ester migration process, mediated by SmI2,
that delivers stereodefined alkene hydrocarboxylation products via
radical cyclization of acyclic ester groups in α-carbomethoxy
δ-lactones. Isotopic labeling experiments and computational
studies have been used to probe the mechanism of the migration. We
propose that a switch in conformation redirects single electron transfer
from SmI2 to the acyclic ester group, rather than the “more
reactive” lactone carbonyl. Our study paves the way for the
use of elusive ketyl radicals, derived from acyclic esters, in SmI2-mediated reductive cyclizations.
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Affiliation(s)
- Charlotte Morrill
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K
| | - Áron Péter
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K
| | - Ilma Amalina
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K
| | - Emma Pye
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K
| | - Giacomo E M Crisenza
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K
| | - Nikolas Kaltsoyannis
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K
| | - David J Procter
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K
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17
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Abstract
Herein, we report an enantioselective and convergent total synthesis of (+)-pepluanol A, a structurally intriguing Euphorbia diterpenoid natural product featuring a 5/6/7/3-fused tetracyclic skeleton, from known building blocks in 11 steps. The successful strategy relies on a phenyl selenide-mediated Morita-Baylis-Hillman type reaction as a connective step, forging the precursor for the key intramolecular Diels-Alder reaction to construct the congested 5/6/7-tricyclic framework. A diastereoconvergent cascade starting with an acid-induced removal of the C1-MOM protecting group followed by a retro-aldol/aldol reaction resulted in the formation of a single diastereomer. This stereoconvergency allowed for the successful substrate-controlled diastereoselective cyclopropanation of an advanced intermediate to establish the full carboskeleton of (+)-pepluanol A (1).
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Affiliation(s)
- Po Yuan
- Institute of Organic Chemistry, University of Konstanz, Universitätsstrasse 10, Konstanz 78464, Germany
| | - Tanja Gaich
- Institute of Organic Chemistry, University of Konstanz, Universitätsstrasse 10, Konstanz 78464, Germany
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18
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Abstract
Terpenoids constitute a broad class of natural compounds with tremendous variability in structure and bioactivity, which resulted in a strong interest of the chemical community to this class of natural products over the last 150 years. The presence of strained small rings renders the terpenoid targets interesting for chemical synthesis, due to limited number of available methods and stability issues. In this feature article, a number of recent examples of total syntheses of terpenoids with complex carbon frameworks featuring small rings are discussed. Specific emphasis is given to the new developments in strategical and tactical approaches to construction of such systems.
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Affiliation(s)
- Gleb A Chesnokov
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
| | - Karl Gademann
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
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19
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Abstract
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The therapeutic properties of Curcuma (ginger
and turmeric’s family) have long been known in traditional
medicine. However, only recently have guaiane-type sesquiterpenes
extracted from Curcuma phaeocaulis been
submitted to biological testing, and their enhanced bioactivity was
highlighted. Among these compounds, phaeocaulisin A has shown remarkable
anti-inflammatory and anticancer activity, which appears to be tied
to the unique bridged acetal moiety embedded in its tetracyclic framework.
Prompted by the promising biological profile of phaeocaulisin A and
by the absence of a synthetic route for its provision, we have implemented
the first enantioselective total synthesis of phaeocaulisin A in 17
steps with 2% overall yield. Our route design builds on the identification
of an enantioenriched lactone intermediate, tailored with both a ketone
moiety and a conjugated alkene system. Taking advantage of the umpolung
carbonyl-olefin coupling reactivity enabled by the archetypal single-electron
transfer (SET) reductant samarium diiodide (SmI2), the
lactone intermediate was submitted to two sequential SmI2-mediated cyclizations to stereoselectively construct the polycyclic
core of the natural product. Crucially, by exploiting the innate inner-sphere
nature of carbonyl reduction using SmI2, we have used a
steric blocking strategy to render sites SET-unreceptive and thus
achieve chemoselective reduction in a complex substrate. Our asymmetric
route enabled elucidation of the naturally occurring isomer of phaeocaulisin
A and provides a synthetic platform to access other guaiane-type sesquiterpenes
from C. phaeocaulis—as well
as their synthetic derivatives—for medicinal chemistry and
drug design.
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Affiliation(s)
- Áron Péter
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Giacomo E M Crisenza
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - David J Procter
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
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20
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Chen Z, Zhao K, Jia Y. Bioinspired Total Synthesis of (+)-Euphorikanin A. Angew Chem Int Ed Engl 2022; 61:e202200576. [PMID: 35165997 DOI: 10.1002/anie.202200576] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Indexed: 11/12/2022]
Abstract
We have achieved a bioinspired total synthesis of (+)-euphorikanin A, which possesses an intriguing and complex 5/6/7/3-fused tetracyclic skeleton bearing a bridged [3.2.1]-γ-lactone moiety. Key transformations include stereoselective alkylation and aldol condensation to install the main stereocenters, an intramolecular nucleophile-catalyzed aldol lactonization of carboxylic acid-ketone to assemble the five-membered ring, a McMurry coupling to construct the seven-membered ring, and a biomimetic benzilic acid type rearrangement to form the bridged [3.2.1]-γ-lactone moiety.
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Affiliation(s)
- Zhuang Chen
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, and Chemical Biology Center, Peking University, Xue Yuan Rd. 38, Beijing, 100191, China
| | - Kuan Zhao
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, and Chemical Biology Center, Peking University, Xue Yuan Rd. 38, Beijing, 100191, China
| | - Yanxing Jia
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, and Chemical Biology Center, Peking University, Xue Yuan Rd. 38, Beijing, 100191, China
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Chen Z, Zhao K, Jia Y. Bioinspired Total Synthesis of (+)‐Euphorikanin A. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202200576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Zhuang Chen
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences and Chemical Biology Center Peking University Xue Yuan Rd. 38 Beijing 100191 China
| | - Kuan Zhao
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences and Chemical Biology Center Peking University Xue Yuan Rd. 38 Beijing 100191 China
| | - Yanxing Jia
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences and Chemical Biology Center Peking University Xue Yuan Rd. 38 Beijing 100191 China
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