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Peng Y, Xu XB, Xiao J, Wang YW. Nickel-mediated stereocontrolled synthesis of spiroketals via tandem cyclization–coupling of β-bromo ketals and aryl iodides. Chem Commun (Camb) 2014; 50:472-4. [DOI: 10.1039/c3cc47780k] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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2
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Fremlin L, Farrugia M, Piggott AM, Khalil Z, Lacey E, Capon RJ. Reveromycins revealed: new polyketide spiroketals from Australian marine-derived and terrestrial Streptomyces spp. A case of natural products vs. artifacts. Org Biomol Chem 2010; 9:1201-11. [PMID: 21152660 DOI: 10.1039/c0ob00654h] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chemical analysis of fermentation products from two Australian Streptomyces isolates yielded all four known and twelve new examples of the rare reveromycin class of polyketide spiroketals, including hemi-succinates, hemi-fumarates and hemi-furanoates. Reveromycins were identified with the aid of HPLC-DAD-MS and HPLC-DAD-SPE-NMR methodology, and structures were assigned by detailed spectroscopic analysis. The structural and mechanistic requirements for an unprecedented hemi-succinate : ketal-succinyl equilibrium were defined and provided a basis for proposing that reveromycin 4'-methyl esters and 5,6-spiroketals were artifacts. A plausible reveromycin polyketide biosynthesis is proposed, requiring a 2-methylsuccinyl-CoA starter unit, with flexible incorporation of a C(6-8) polyketide chain extension and diacid esterification units. Structure activity relationship investigations by co-metabolites were used to assess the anticancer, antibacterial and antifungal properties of reveromycins.
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Affiliation(s)
- Leith Fremlin
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia
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Markiewicz JT, Schauer DJ, Löfstedt J, Corden SJ, Wiest O, Helquist P. Synthesis of 4-Methyldienoates Using a Vinylogous Horner−Wadsworth−Emmons Reagent. Application to the Synthesis of Trichostatic Acid. J Org Chem 2010; 75:2061-4. [DOI: 10.1021/jo902422y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- John T. Markiewicz
- Department of Chemistry and Biochemistry, Walther Cancer Research Center, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556
| | - Douglas J. Schauer
- Department of Chemistry and Biochemistry, Walther Cancer Research Center, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556
| | - Joakim Löfstedt
- Department of Chemistry and Biochemistry, Walther Cancer Research Center, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556
| | - Steven J. Corden
- Department of Chemistry and Biochemistry, Walther Cancer Research Center, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556
| | - Olaf Wiest
- Department of Chemistry and Biochemistry, Walther Cancer Research Center, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556
| | - Paul Helquist
- Department of Chemistry and Biochemistry, Walther Cancer Research Center, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556
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Brand C, Rauch G, Zanoni M, Dittrich B, Werz DB. Synthesis of [n,5]-spiroketals by ring enlargement of donor-acceptor-substituted cyclopropane derivatives. J Org Chem 2010; 74:8779-86. [PMID: 19860460 DOI: 10.1021/jo901902g] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Exocyclic enol ethers served as starting materials for the synthesis of [n,5]-spiroketals (n = 5, 6). A metal-mediated cyclopropanation using ethyl diazoacetate afforded spiroannelated cyclopropane derivatives bearing an ester group. A reduction of the corresponding ester by LiAlH(4), followed by subsequent oxidation using hypervalent iodine reagents, produced [n,5]-spiroketals in moderate to good yields. The key step within this three-step sequence is the ring enlargement of the three-membered ring with an oxygen donor and a carbonyl acceptor group into the five-membered enol ether system. Catalytic amounts of the Lewis acid Yb(OTf)(3) facilitate the ring enlargement and increase the yield of the corresponding spiroketal in many cases. When Yb(OTf)(3) was used, our experiments revealed an open transition state rather than a concerted mechanism because the stereochemistry of the spirocenter was not conserved during the ring enlargement. As a result, the thermodynamically more favored anomeric [n,5]-spiroketal was observed as the major product. All the structures were established unambiguously by NOESY experiments.
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Affiliation(s)
- Christian Brand
- Institut für Organische und Biomolekulare Chemie der Georg-August-Universität Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
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Virolleaud MA, Sridharan V, Mailhol D, Bonne D, Bressy C, Chouraqui G, Commeiras L, Coquerel Y, Rodriguez J. Consecutive reactions with sulfoximines: a direct access to 2-sulfonimidoylylidene tetrahydrofurans and 6-sulfonimidoylmethyl-3,4-dihydro-2H-pyrans. Tetrahedron 2009. [DOI: 10.1016/j.tet.2009.09.080] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Rizzacasa MA, Pollex A. The hetero-Diels–Alder approach to spiroketals. Org Biomol Chem 2009; 7:1053-9. [DOI: 10.1039/b819966n] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Raju BR, Saikia AK. Asymmetric synthesis of naturally occurring spiroketals. Molecules 2008; 13:1942-2038. [PMID: 18794795 PMCID: PMC6245485 DOI: 10.3390/molecules13081942] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Revised: 08/22/2008] [Accepted: 08/22/2008] [Indexed: 12/03/2022] Open
Abstract
Spiroketals are widely found as substructures of many naturally occurring compounds from diverse sources including plants, animals as well as microbes. Naturally occurring spiroketals are biologically active and most of them are chiral molecules. This article aims at reviewing the asymmetric synthesis of biologically active spiroketals for last 10 years (1998-2007).
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Affiliation(s)
| | - Anil K. Saikia
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India E-mail:
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Guillarme S, Plé K, Banchet A, Liard A, Haudrechy A. Alkynylation of chiral aldehydes: alkoxy-, amino-, and thio-substituted aldehydes. Chem Rev 2007; 106:2355-403. [PMID: 16771453 DOI: 10.1021/cr0509915] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Stéphane Guillarme
- Laboratoire de Glycosynthèse, UMR 6519, UFR Sciences Exactes et Naturelles, Bât. 18, BP 1039, 51687 Reims Cedex 2, France
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Abstract
The asymmetric total synthesis of (-)-reveromycin A is described. The key steps involved a Lewis acid catalyzed inverse electron demand hetero-Diels-Alder reaction followed by hydroboration/oxidation to afford the spiroketal core 4 in a highly stereoselective manner and introduction of the C18 hemisuccinate by high-pressure acylation.
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Affiliation(s)
- Mariana El Sous
- School of Chemistry, The University of Melbourne, Victoria 3010, Australia
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Cuzzupe AN, Hutton CA, Lilly MJ, Mann RK, McRae KJ, Zammit SC, Rizzacasa MA. Total synthesis of the epidermal growth factor inhibitor (-)-reveromycin B. J Org Chem 2001; 66:2382-93. [PMID: 11281779 DOI: 10.1021/jo001646c] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The total synthesis of the epidermal growth factor inhibitor reveromycin B (2) in 25 linear steps from chiral methylene pyran 13 is described. The key steps involved an inverse electron demand hetero-Diels-Alder reaction between dienophile 13 and diene 12 to construct the 6,6-spiroketal 11 which upon oxidation with dimethyldioxirane and acid catalyzed rearrangement gave the 5,6-spiroketal aldehyde 9. Lithium acetylide addition followed by oxidation/reduction and protective group manipulation provided the reveromycin B spiroketal core 8 which was converted into the reveromycin A (1) derivative 6 in order to confirm the stereochemistry of the spiroketal segment. Introduction of the C1-C10 side chain began with sequential Wittig reactions to form the C8-C9 and C7-C6 bonds, and a tin mediated asymmetric aldol reaction installed the C4 and C5 stereocenters. The final key steps to the target molecule 2 involved a Stille coupling to introduce the C21-C22 bond, succinoylation, selective deprotection, oxidation, and Wittig condensation to form the final C2-C3 bond. Deprotection was effected by TBAF in DMF to afford reveromycin B (2) in 72% yield.
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Affiliation(s)
- A N Cuzzupe
- School of Chemistry, The University of Melbourne, Victoria 3010, Australia
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11
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Five-Membered Ring Systems: With O & N Atoms. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s0959-6380(01)80013-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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12
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Abstract
The first asymmetric synthesis of (+)-crocacin C (3) is described which served to confirm the absolute configuration of this compound. The key step in the sequence was the stereoselective assembly of the (E,E)-diene amide side chain by a Stille cross-coupling between the stannane 5 and vinyl iodide 6.
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Affiliation(s)
- J T Feutrill
- School of Chemistry, The University of Melbourne, Victoria 3010, Australia
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13
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El Sous M, Rizzacasa MA. Hetero-Diels–Alder synthesis of the spiroketal fragment of reveromycin A. Tetrahedron Lett 2000. [DOI: 10.1016/s0040-4039(00)01494-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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