New bromotriterpene polyethers from the Indian alga Chondria armata

Ciavatta, M. L.; Wahidulla, Solimabi; D’Souza, Lisette; Scognamiglio, Gennaro; Cimino, Guido

doi:10.1016/s0040-4020(00)01031-0

Cited by 22 publications

(23 citation statements)

References 12 publications

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“…245 .0]undecane unit thereby affording a 7/7/6-ring system, which further connects via single bonds either to an oxolane ring (380) 240 or to an oxepane ring (381−386). 249 In contrast, two other triterpenes, enshuol (387) well as in the sea hare Dolabella auricularia, 252,253 which is known to feed on marine algae like Laurencia species.…”

Section: Halogenated Triterpenes/polyethersmentioning

confidence: 99%

Halogenated Organic Molecules of Rhodomelaceae Origin: Chemistry and Biology

et al. 2013

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Section: Halogenated Triterpenes/polyethersmentioning

confidence: 99%

Halogenated Organic Molecules of Rhodomelaceae Origin: Chemistry and Biology

et al. 2013

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“…8 In particular, armatol A ( 5 ) is the only natural product among the oxasqualenoid polyethers that contains a 7,7,6-fused tricycle in which one of the rings is an oxepene. Our interest in this family of natural products is bolstered by a lack of absolute and complete relative stereochemical assignment, either by advanced spectroscopic techniques or synthetic studies.…”

Section: Introductionmentioning

confidence: 99%

Total syntheses of the squalene-derived halogenated polyethers ent -dioxepandehydrothyrsiferol and armatol A via bromonium- and Lewis acid-initiated epoxide-opening cascades

Underwood

Tanuwidjaja

et al. 2013

Tetrahedron

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Herein we describe in full our investigations leading to the first total syntheses of ent-dioxepandehydrothyrsiferol and armatol A. Discovery of a bromonium-initiated epoxide-opening cascade enabled novel tactics for constructing key fragments found in both natural products and have led us to revise the proposed biogeneses. Other common features found in the routes include convergent fragment coupling strategies to assemble the natural products’ backbones and the use of epoxide-opening cascades for rapid constructions of the fused polyether subunits. Through de novo synthesis of armatol A, we elucidate the absolute and relative configuration of this natural product.

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“…Methyl-substituted oxepines 48 have also been postulated as intermediates in the metabolism of arenes by liver enzymatic systems [39]. Some annelated oxepines are found in nature and these include bauhiniastatin (49) [40], janoxepin (50) [41], and perillosin (51) [42], and some relevant pharmacological activities have been described for some dibenzoxepine derivatives inter alia anxiolytic activity for 52 [43] and anti-inflammatory action for artocarpol (53), a natural product isolated from the root bark of Artocarpus rigida [44].…”

Section: Relevant Natural and Useful Compoundsmentioning

confidence: 99%

“…A remarkable number of natural marine products contain oxepane or a reduced oxepine in their structure [46]. Representative examples are isolaurepinnacin (55) [47] and lobatrienetriol (56) [48], both of which are structurally based on a monocyclic tetrahydrooxepine, armatol A (57) [49], with two oxepane and one tetrahydrooxepine rings, and ciguatoxin 3C (58), which is one of the most powerful polyether neurotoxins [50].…”

Section: Relevant Natural and Useful Compoundsmentioning

confidence: 99%

Seven‐Membered Heterocycles: Azepines, Benzo Derivatives and Related Systems

Vaquero

Cuadro

Herradón

2011

Modern Heterocyclic Chemistry

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The replacement of a carbon atom by a heteroatom in a seven-membered carbocycle leads to the corresponding seven-membered heterocyclic ring system. Different types of heterocycles can be formed depending on the nature of the carbocycle. In a cycloheptatriene the replacement can involve any of the six sp 2 hybridized carbons or the sp 3 carbon atom, whereas in cycloheptane all carbon atoms are equivalent and replacement affords exclusively the fully saturated heterocyclic systems. Partially saturated seven-membered heterocycles can be viewed as derivatives or related systems of these two main seven-membered heterocyclic units arising from carbon replacement in cycloheptatriene and in cycloheptane. Replacement of the sp 3 hybridized carbon atom in cycloheptatriene by a nitrogen leads to an azacycloheptatriene known as 1H-azepine (1) and the corresponding 2H-, 3H-, and 4H-azepines (2-4) are the tautomeric forms generated by the replacement of the sp 2 carbons. 1H-Azepine is an unstable red oil that is prone to rearrange to the also unstable 3H-azepine in the presence of acids and bases. However, this tautomer seems to be more stable than both 4H-and 2H-azepine. The structures related to 1H-azepine that bear an oxygen or sulfur atom are known as oxepine (5) and thiepine (6) (thiepin is favored by Chemical Abstracts Service). Oxepine is much more stable than thiepine and has been synthesized, isolated, and characterized at room temperature while thiepine has not been detected to date. Stable monocyclic thiepines were prepared and characterized in the 1980s. Azepines, oxepines, and thiepines that are constrained to planar or almost planar conformations should be antiaromatic molecules with negative resonance energy and, as a consequence, these compounds are unknown.The fully saturated seven-membered heterocycle containing one nitrogen is azepane (7) (hexahydroazepine or perhydroazepine); the oxygen and sulfur analogues are known as oxepane (8) and thiepane (9). All of these compounds are stable and show typical behavior of secondary amine, ether and thioether, respectively. TwoModern Heterocyclic Chemistry, First Edition. Edited

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New bromotriterpene polyethers from the Indian alga Chondria armata

Cited by 22 publications

References 12 publications

Halogenated Organic Molecules of Rhodomelaceae Origin: Chemistry and Biology

Halogenated Organic Molecules of Rhodomelaceae Origin: Chemistry and Biology

Total syntheses of the squalene-derived halogenated polyethers ent -dioxepandehydrothyrsiferol and armatol A via bromonium- and Lewis acid-initiated epoxide-opening cascades

Seven‐Membered Heterocycles: Azepines, Benzo Derivatives and Related Systems

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