- A New End Game for Aphidicolin
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A highly efficient, stereocontrolled synthesis of aphidicolin from its degradation product, 3α,18-isopropylidenedioxy-17-noraphidicolan-16-one, has been achieved.
- Rizzo, Carmelo J.,Smith, Amos B.
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- Biosynthesis of diterpenoid aphidicolin: Isolation of intermediates from P-450 inhibitor treated mycelia of Phoma betae
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Treatment of Phoma betae with P-450 inhibitors caused accumulation of biosynthetic precursors 2, 3 and 4 of aphidicolin (1). Their structures were elucidated by spectroscopic analysis and they were confirmed by chemical transformations from 1. Isotopicall
- Oikawa, Hideaki,Ohashi, Satoshi,Ichihara, Akitami,Sakamura, Sadao
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p. 7541 - 7554
(2007/10/03)
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- The hydroxylation at C-17 in the biosynthesis of the diterpenoid aphidicolin
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The hydroxylation at C-17 in aphidicolin biosynthesis is inhibited by a 17-thiol. A metabolite hydroxylated at C-17 and retaining the cyclopropane ring was obtained from 3α,18-dihydroxy-15β,16β-methanoaphidicolane whilst aphidicolin itself was obtained from 3α,18-dihydroxyaphidicolane when these substrates were incubated with the fungus, Cephalosporium aphidicola.
- Hanson, James R.,Hitchcock, Peter B.,Jarvis, Andrew G.
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p. 1055 - 1059
(2007/10/03)
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- THE HYDROXYLATION OF GLOBULOL AND 7-EPIGLOBULOL BY CEPHALOSPORIUM APHIDICOLA
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Globulol and 7-epiglobulol were shown to be hydroxylated by Cephalosporium aphidicola on one (C-14) of the methyl groups geminal to the cyclopropane ring in 48.5 and 56percent yield, respectively.The significance of this hydroxylation adjacent to a cyclopropane ring is noted. - Key words: Cephalosporium aphidicola; globulol; 7-epiglobulol; sesquiterpenoid; microbiological hydroxylation.
- Hanson, James R.,Hitchcock, Peter B.,Manickavasagar, Revathy
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p. 1023 - 1026
(2007/10/02)
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- Oxidation of Aphidicolin and Its Conversion into 19-Noraphidicolan-16β-ol
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The preparation of the 3α,18-monoacetonide of aphidicolin and its selective oxidation at C-17, is described.Catalytic oxidation of aphidicolin affords 16β-hydroxy-3-oxo-19-noraphidicolan-17-oic acid.The conversion of this into 19-noraphidicolan-16β-ol and its biotransformation by the fungus, Cephalosporium aphidicola, to a 19-noraphidicolin, is reported.
- Gordon, John F.,Hanson, James R.,Jarvis, Andrew G.,Ratcliffe, Arnold H.
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p. 3019 - 3022
(2007/10/02)
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- Rearrangements of the C/D Ring System of the Tetracyclic Diterpenoid, Aphidicolin
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The generation of a C-16 carbocation in the aphidicolane series by the hydrolysis of a 15β,16β- or a 16β,17-epoxide is shown to lead, inter alia, to skeletal rearrangement products arising from the migration of the C(12)-C(13) bond to C-16.
- Hanson, James R.,Hitchcock, Peter B.,Jarvis, Andrew G.,Ratcliffe, Arnold H.
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p. 1773 - 1778
(2007/10/02)
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- Aphidicolin Synthetic Studies: A Stereocontrolled End Game
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A highly efficient, stereocontrolled synthesis of (+)-aphidicolin 1 from the well-known degradation product, acetonide 17-nor ketone 2a, has been achieved.Key steps included palladium(0)-catalysed carbonylation of the enol triflate derived from 2a and stereoselective epoxidation of the resultant α,β-unsaturated ester.Hydride reduction then furnished the C(16,17) vicinal diol moiety of 1.Similarly transformed to aphidicolin were the Corey 2,2-dimethylpropylidenedioxy synthetic intermediate 2b and the bis-tert-butyldimethylsilyl ether 2c.The latter further served as synthetic precursor to the naturally occurring derivative (+)-aphidicolin 17-acetate 26.The preparation and biological evaluation of the unnatural 16-methoxycarbonyl congeners 28 and 29 are also discussed.
- Rizzo, Carmelo J.,Smith, Amos B.
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p. 969 - 979
(2007/10/02)
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- Studies in Terpenoid Biosynthesis. Part 35. Biosynthetic Sequences leading to the Diterpenoid Aphidicolin in Cephalosporium aphidicola
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-Labelled samples of 18-hydroxyaphidicol-16-ene, 3α,18-dihydroxyaphidicol-16-ene, 16β,17- and 16β,18-dihydroxyaphidicolane, and 3α,16β,18- and 16β,17,18-triyhdroxyaphidicolane have been prepared from aphidicolin and shown to be incorporated into aphidicolin by Cephalosporium aphidicola to the extent of 0.86, 16.4, 3.5, 20.5, 52.6, and 16,9 percent , respectively.These results suggest that although the major pathway of aphidicolin biosynthesis involves the 16β-alcohols , the 16-enes may also utilized whilst a metabolic grid relationship may exist between the variously hydroxylated 16β-alcohols.
- Ackland, Mark J.,Gordon, John F.,Hanson, James R.,Yeoh, Boon Leng,Ratcliffe, Arnold H.
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p. 1477 - 1480
(2007/10/02)
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- Studies in Terpenoid Biosynthesis. Part 38. The Role of an 16β,17-Epoxyaphidicolane in the Minor Biosynthetic Pathway Leading to Aphidicolin
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The hydroxylation of 2H, 17-2H3>aphidicolane-3α,16β,18-triol at C-17 in the biosynthesis of aphidicolin is shown to involve an isotope effect whilst there is no effect in the incorporation of 2H, 17-2H2>aphidicol-16-ene-3α,18-diol suggesting that the transformation of the 16-ene involves epoxidation and hydrolysis rather than hydration and hydroxylation.Feeding experiments suggest that the 16β,17-epoxyaphidicolane-3α,18-diol is involved in this transformation.
- Ackland, Mark J.,Gordon, John F.,Hanson, James R.
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p. 2009 - 2012
(2007/10/02)
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