Metabolites of the higher fungi. Part 23. The punctaporonins. Novel bi-, tri-, and tetra-cyclic sesquiterpenes related to caryophyllene, from the fungus Poronia punctata(Linnaeus:Fries) Fries

Anderson, John R.; Edwards, R. L.; Poyser, J. Philip; Whalley, Anthony J. S.

doi:10.1039/p19880000823

Cited by 45 publications

(40 citation statements)

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“…[9] In allen Fällen (3, 5, 7) bildet sich das Produkt, bei dem der zentrale Cyclobutanring und die anellierten Fünf-oder Sechsringe cis-verknüpft sind (einfache Diastereoselektivität). Die faciale Diastereoselektivität bei der Umsetzung 6!7 kann durch einen Angriff des terminalen Alkens von der Seite des Tetronats interpretiert werden, auf die das stereogene Zentrum an C-5 die Alkenylkette lenkt.Zur Synthese des tricyclischen Skeletts von Punctaporonin C [10] …”

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[2+2]‐Photocycloaddition von Tetronsäureestern

Kemmler

Bach

2003

Angewandte Chemie

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In Zusammenhang mit der Synthese von 2-Oxabicyclo[3.2.0]-heptanen (n = 1) und verwandten Sauerstoffheterocyclen des Typs A (Schema 1) haben wir die Frage untersucht, ob man mithilfe einer Cu-katalysierten intramolekularen [2+2]-Photocycloaddition [1] Tetronsäureester des Typs 2 (Schema 2) lassen sich durch nucleophile Substitution aus Tetronsäure oder ihren Derivaten und entsprechenden w-Alkenolen sehr leicht herstellen. [6] In einer ersten Versuchsreihe untersuchten wir die intramolekulare [2+2]-Photocycloaddition der O-verbrückten Diene 2. Die zum Tetrahydrofuran 3 a und zum Tetrahydropyran 3 b führenden Reaktionen verliefen glatt [7,8] Die analogen Versuche in Aceton als Lösungsmittel oder mit einem Triplettsensibilisator (Benzophenon, Acetophenon) in Ether oder Acetonitril verliefen weniger sauber und führten zur Bildung von Nebenprodukten. Die Photocycloaddition ist im Sinne einer intramolekularen Reaktion keiner Restriktion bezüglich der Position der Seitenkette unterworfen. In Substrat 4 befindet sich die w-Alkenylkette an der Position C-3, in Substrat 6 an C-5 (Schema 3). 4 und 6 ergaben die strukturell interessanten tricyclischen Bestrahlungsprodukte 5 und 7. Auf diese Weise eröffnet sich ein effizienter Zugang zu unterschiedlich substituierten Bicyclo[3.2.0]heptanen, einem Strukturtyp, der in zahlreichen Naturstoffen vertreten ist. [9] In allen Fällen (3, 5, 7) bildet sich das Produkt, bei dem der zentrale Cyclobutanring und die anellierten Fünf-oder Sechsringe cis-verknüpft sind (einfache Diastereoselektivität). Die faciale Diastereoselektivität bei der Umsetzung 6!7 kann durch einen Angriff des terminalen Alkens von der Seite des Tetronats interpretiert werden, auf die das stereogene Zentrum an C-5 die Alkenylkette lenkt.Zur Synthese des tricyclischen Skeletts von Punctaporonin C [10]

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[2+2]‐Photocycloaddition von Tetronsäureestern

Kemmler

Bach

2003

Angewandte Chemie

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“…The coupling patterns and NOESY correlations for the relevant protons in 2 were nearly identical to those of 1, indicating that they possess the same relative configuration, except for the additional stereogenic center C-9, which was assigned by comparison of the coupling constant between H-9 and H-12 (9.7 Hz) with that reported for 4. 9,18 This assignment was supported by NOESY correlations of H-9 with H-1 and Me-16. Considering the absolute configuration established for 1 by the modified Mosher method, C-9 was deduced to have the S configuration.…”

Section: Resultsmentioning

confidence: 65%

“…The vicinal coupling constants observed for H-1 with H-11 and H-12 were 7.4 and 6.5 Hz, respectively, suggesting their cis-relative orientation, 17 consistent with a similar THF moiety found in the known compound punctaporonin C (4). 9,18 NOESY correlations of Me-13 with H-2, H-3a, and H-6 indicated that these protons are all on the same face of the ring system, whereas those of H-3b with H-1 and Me-14, and of H-12 with Me-16 were used to place them on the opposite face. Collectively, these data allowed assignment of the relative configuration of 1.…”

Section: Resultsmentioning

confidence: 99%

“…isolated from Taxus brevifolia; 1,2 pestalotiopsolide A, teadolidol, and 6-epiteadolidol, highly oxidized caryophyllenes from a Pestalotiopsis sp. endophytic to the bark of Pinus taeda; 3 the 6-hydroxpunctaporonins, antibacterial metabolites from a fungicolous Pestalotiopsis disseminata; 4 fuscoatrol A, a cytotoxic agent from a marine-derived Humicola fuscoatra KMM 4629; 5 the punctaporonins (also named as punctatins), antifungal agents from a coprophilous Poronia punctata; [6][7][8][9][10][11] walleminol and walleminone, two cis-fused iso-caryophyllenes from the toxigenic fungus Wallemia sebi; 12 and Sch 725432, 601253, 601254, and 725434, antifungal agents from Chrysosporium pilosum. 13 During an ongoing search for new bioactive natural products from fungi of unique habitats, we initiated chemical studies of the fungi either inhabiting the fruiting body and larvae of Cordyceps sinensis 14 or its surface soil.…”

Section: Introductionmentioning

confidence: 99%

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Cytosporinols A-C, new caryophyllene sesquiterpenoids from Cytospora sp.

Li¹,

Li²,

Cui³

et al. 2012

Nat. Prod. Bioprospect.

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Abstract:Three new caryophyllene sesquiterpenoids, cytosporinols A-C (1-3), have been isolated from solid cultures of Cytospora sp. The structures of 1-3 were elucidated primarily by NMR spectroscopy, and 3 was further confirmed by X-ray crystallography. The absolute configurations of the C-11 secondary alcohol in 1 and the 6,8-diol moiety in 3 were deduced using the modified Mosher and Snatzke's method, respectively. Compounds 2 and 3 showed moderate cytotoxicity against HeLa cells.

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“…For the synthesis of the tricyclic skeleton of punctaporonin C [10] we investigated the intramolecular [2+2] photocycloaddition of the tetronate 8 (Scheme 3), which was readily prepared from the known compound trans-2-vinyl-1-cyclopentanol [11] by a Mitsunobu reaction with tetronic acid. The photocycloaddition again proceeded smoothly to provide the tetracycle 9 as the sole product with perfect facial diastereoselectivity.…”

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confidence: 99%

[2+2] Photocycloaddition of Tetronates

Kemmler

Bach

2003

Angew Chem Int Ed

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In connection with the synthesis of 2-oxabicyclo[3.2.0]heptanes (n = 1) and related oxygen-containing heterocycles of the general formula A, we postulated that a Cu-catalyzed intramolecular [2+2] photocycloaddition [1] of enol ethers B might provide a general approach to this class of compounds (Scheme 1). In contrast to simple homoallyl vinyl ethers, which have been shown to undergo Cu-catalyzed [2+2] photocycloadditions, [2] the more highly substituted substrates of type B that we tested did not react as desired, but decomposed in the presence of the copper salts. As an alternative to enol ethers we examined derivatives of tetronic acid [3] (1, R = H) in direct [2+2] photocycloaddition reactions and found that these building blocks deliver excellent results under irradiation conditions. Although the [2+2] photocycloaddition of 3[2H]-furanones [4] and 2[5H]-furanones [5] is well known, to the best of our knowledge no study of tetronates in [2+2] photocycloaddition reactions has yet been conducted. Herein, we report the first [2+2] photocycloaddition reactions of these compounds.Tetronates of the general formula 2 are readily available from tetronic acid or its derivatives and w-alkenols by nucleophilic substitution.[6] In a first series of experiments we investigated the intramolecular [2+2] photocycloaddition of the O-bridged dienes 2 (Scheme 2). The reactions proceeded smoothly [7,8] to produce the tetrahydrofuran 3 a and the tetrahydropyran 3 b with excellent simple diastereoselectivity. In each case a single product was observed in diastereomerically pure form. The relative configuration was unambiguously assigned by NOESY experiments and X-ray crystallographic analysis. The light source in the irradiation experiments was either a TNN 15/32 (Original

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Metabolites of the higher fungi. Part 23. The punctaporonins. Novel bi-, tri-, and tetra-cyclic sesquiterpenes related to caryophyllene, from the fungus Poronia punctata(Linnaeus:Fries) Fries

Cited by 45 publications

References 4 publications

[2+2]‐Photocycloaddition von Tetronsäureestern

[2+2]‐Photocycloaddition von Tetronsäureestern

Cytosporinols A-C, new caryophyllene sesquiterpenoids from Cytospora sp.

[2+2] Photocycloaddition of Tetronates

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