Superacidic cyclization of higher terpenoid acids and their esters

Vlad, P. F.; Ungur, Nicon; Tuen, Nguen Van

doi:10.1007/bf00713614

Cited by 23 publications

(12 citation statements)

References 6 publications

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“…The hexane-and EtOAc-soluble fractions showed HDAC inhibitory activity of more than 60% at 250 lg/ml. Fractionation of the hexane-soluble fraction afforded (+)-hardwickiic acid (4) [4] as a major diterpene constituent together with three minor diterpenes, (4aa,6b,8ab)-1-hydroxymethyl-5(R)-[2-(3-furanyl)ethyl]-5,6,8a-trimethyl-3,4,4a,5,6,7,8,8a-octahydronaphthalene (1) [5], (+)-eperua-7,13-dien-15-oic acid (2) [6], and (+)-eperua-8,13-dien-15-oic acid (3) [7]. On the other hand, the EtOAc-soluble fraction yielded two flavonoids, quercetin 3-O-a-rhamnside (quercitrin) (5) [8] and kaempferol 3-O-a-rhamnside (afzelin) (6) [9] (Fig.…”

Section: Resultsmentioning

confidence: 99%

First isolation of three diterpenes as naturally-occurring compounds from Sindora siamensis

et al. 2006

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Section: Resultsmentioning

confidence: 99%

First isolation of three diterpenes as naturally-occurring compounds from Sindora siamensis

et al. 2006

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“…Because of the presence of verrucosin-4 (46) among the natural occurring verrucosins, [3,20-13 C 2 ]-geranyl geranoic acid and the corresponding glyceride were prepared (Ungur et al, 2000) according to the scheme reported in Figure 15 (Vlad et al, 1995). Both compounds were injected into the digestive glands but no incorporation was detected in verrucosins (unpublished result).…”

Section: Biosynthesis In Nudibranchiamentioning

confidence: 99%

Biosynthesis in opisthobranch molluscs: General outline in the light of recent use of stable isotopes

et al. 2004

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The use of stable isotopes has been recently introduced in the biosynthetic studies of metabolites produced by opisthobranch molluscs. This methodology offers numerous advantages since it avoids the complex and tedious manipulations of potentially dangerous radioactive compounds and gives unequivocal evidence for the incorporation. In these studies, high field NMR spectroscopy is a particularly useful tool to localize the labeled atoms in the molecule. This chapter updates the biosynthetic studies on opisthobranch molluscs with particular attention to the recent experiments with precursors labeled with stable isotopes. Opisthobranchs are able to biosynthesize de novo a wide array of chemical skeletons including polyketides, polypropionates, acetogenins, and terpenoids. The studies regarding this latter class is proposed in the light of the recent debate about classical and independent mevalonate pathway.

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“…The cyclization of individual esters 7 and 8 with SnCl 4 (benzene, r.t., 1 h) led to scalarane esters 9 and 10, with moderate yields of 25 and 18%, respectively. Later on, Vlad and collaborators (1992;1995b) cyclized the same esters 7 and 8 to scalaranes 9 and 10, respectively, under the action of fluorosulfonic acid at low temperature. The yields of target scalaranes were higher ($80% for 9 and 74% for 10).…”

Section: Synthetic Strategies Towards Scalarane Skeletonmentioning

confidence: 99%

Synthetic paths towards scalaranes: Assembling the scalaranic skeleton and further transformations

Ungur

Kulciţki

2004

Phytochem Rev

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The family of scalaranic sesterterpenoids has been known since the early 70s, but they have attracted the attention of synthetic organic chemists only in the last decade. These marine natural products are considered secondary metabolites of marine organisms and have shown promising biological properties. Synthetic approaches towards scalaranes are discussed in the present review. Scalaranes are quite complex compounds, with many chiral centers and their transformations are strongly directed by steric effects of different functional groups attached to the tetracyclic framework. Therefore, methods of assembling the scalaranic skeleton are examined first, followed by the synthesis of natural products or their analogues on the basis of the available tetracyclic template.

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Superacidic cyclization of higher terpenoid acids and their esters

Cited by 23 publications

References 6 publications

First isolation of three diterpenes as naturally-occurring compounds from Sindora siamensis

First isolation of three diterpenes as naturally-occurring compounds from Sindora siamensis

Biosynthesis in opisthobranch molluscs: General outline in the light of recent use of stable isotopes

Synthetic paths towards scalaranes: Assembling the scalaranic skeleton and further transformations

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