- The first biomimetic synthesis of a diterpenoid with the ent-verrucosin A/B skeleton
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The first biomimetic synthesis of methyl (8S,9R,13R,14R)-4,4,8,9,13-pentamethyl-20(10 → 9)-abeo-ent-isocopal-5(10),11(12)-dien-15-oate - a diterpenoid with the ent-verrucosin A/B skeleton has been performed by electrophilic isomerization of methyl 12α-hydroxy-ent-isocopal-13(16)-en-15-oate. The structure and stereochemistry of the synthesized compound have been established on the basis of spectroscopic data.
- Grinco, Marina,G?rbu, Vladilena,Gorincioi, Elena,Barba, Alic,Kulci?ki, Veaceslav,Ungur, Nicon
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- Isoagatholactone, a diterpene of a new structural type from the sponge Spongia officinalis
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A new diterpene, isoagatholactone, isolated from the sponge Spongia officinalis, is the first natural compound with the carbon skeleton of isoagathic acid (2), the acid-catalyzed cyclization product of agathic acid (1). Structure 4 was assigned to isoagatholactone on spectral grounds and chemical correlation with grindelic acid (5).
- Cimino,De Rosa,De Stefano,Minale
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- Scalable synthesis of methyl ent-isocopalate and its derivatives
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An efficient and convenient synthetic route was developed to prepare the tricycle diterpene intermediates 1-3 starting from commercially available (-)-sclareol. This improved approach involving four-step reactions provides large-scale (30-40 g) methyl ent-isocopalate in 61% overall yield, which could supply sufficient material for the synthesis of marine natural products containing tricyclic diterpenes.
- Hua, Si-Kai,Wang, Jing,Chen, Xi-Bo,Xu, Zhong-Yu,Zeng, Bu-Bing
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experimental part
p. 1142 - 1144
(2011/03/21)
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- Stereoselective Total Syntheses of (+/-)-Isoagatholactone and (+/-)-12α-Hydroxyspongia-13(16),14-diene, Two Marine Sponge Metabolites
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The highly efficient, stereoselective syntheses of (+/-)-isoagatholactone (1a) and (+/-)-12α-hydroxyspongia-13(16),14-diene (3e), a fundamental skeleton of spongiadiol (3a) and its related furanoid diterpenes, are described. (+/-)-Labda-8(20),13-dien-15-oic acid (6), chosen as the starting material, was cyclised to the known tricyclic compound (2b), which after methylation was subjected to photooxygenation, yielding the allylic alcohol (7a).Refluxing of the alcohol (7a) with 3.5percent sulphuric acid in dioxan afforded the lactone (1b), which after reduction with lithium aluminium hydride led to the diol (2g).Subsequent oxidation of this diol with Collins reagent provided the desired compound (1a).The key precursor for the synthesis of compound (3e) was the allylic alcohol (7a) obtained above.On epoxidation the alcohol (7a) gave the epoxide (13), which by the action with lithium di-isopropylamide led to the α,β-unsaturated γ-lactone (14).Subsequent reduction of this lactone with di-isobutylaluminium hydride afforded the furan (3e).
- Nakano, Tatsuhiko,Hernandez, Maria Isabel
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p. 135 - 139
(2007/10/02)
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- TOTAL SYNTHESES OF (+/-)-ISOAGATHOLACTONE AND (+/-)-12α-HYDROXYSPONGIA-13(16),14-DIEN
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(+/-)-Isoagatholactone 1 and (+/-)-12α-hydroxyspongia-13(16),14-dien 2b, a fundamental skeleton of spongiadiol 2a and its congeners, have been synthesized from (+/-)-labda-8(20),13-dien-15-oic acid 3.
- Nakano, Tatsuhiko,Hernandez, Maria Isabel
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p. 1423 - 1426
(2007/10/02)
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