- Podocarpane-to-spongian skeleton conversion. Synthesis of (+)-isoagatholactone and (-)-spongia-13(16),14-diene
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A stereoselective synthesis of the spongian diterpenes (+)-isoagatholactone 5 and (-)-spongia-13(16),14-diene 6 is achieved starting from (+)-podocarp-8(14)-en-13-one 3 (R=H) via the common intermediate β-hydroxy ketone 13.
- Abad, Antonio,Agullo, Consuelo,Arno, Manuel,Marin, M. Luisa,Zaragoza, Ramon J.
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- CYCLIZATION AND REARRANGEMENT OF DITERPENOIDS. SYNTHESIS OF ISOAGATHOLACTONE AND METHYL SPONGIA-13(16),14-DIEN-19-OATE
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The synthesis of isoagatholactone has been effected by the successive oxidation of (14)R-isoagath-12-en-15-ol with selenium dioxide and manganese dioxide.Methyl spongia-13(16),14-dien-19-oate has been obtained by the cyclization of methyl lambertianate with 100percent sulfuric or fluorosulfonic acid.
- Vlad, P. F.,Ungur, N. D.
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p. 685 - 691
(2007/10/02)
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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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- Stereoselective Synthesis of the Novel Marine Diterpene (+)-Isoagatholactone
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The synthesis of (+)-isoagatholactone (1) from (+)-manool (4) via the key intermediate ent-methyl isocopalate (2) is described.
- Imamura, Paulo M.,Sierra, Manuel Gonzalez,Ruveda, Edmundo A.
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p. 734 - 735
(2007/10/02)
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