Synthesis of Marine Polycyclic Polyethers via Endo-Selective Epoxide-Opening Cascades

Vilotijević, Ivan; Jamison, Timothy F.

doi:10.3390/md8030763

Cited by 81 publications

(44 citation statements)

References 165 publications

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“…A related bis-ether structure is also thought to be an intermediate before the formation of bridged ketal structure in pectenotoxins produced by dinoflagellates (Van Wagoner et al, 2014). The ether ring-formation of two tetrahydrofuran rings in 1 occurs tentatively via 5-exo-tet reaction instead of 6-endo-tet ringformation, which is favoured in the formation of ladder polyether toxins such as brevetoxins and yessotoxins (Vilotijevic and Jamison, 2010). A possible mechanism for formation of 1 is presented in Fig.…”

Section: Biosynthesismentioning

confidence: 99%

Identification of gymnodimine D and presence of gymnodimine variants in the dinoflagellate Alexandrium ostenfeldii from the Baltic Sea

Harju

Koskela

Kremp

et al. 2016

Toxicon

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a b s t r a c tGymnodimines are lipophilic toxins produced by the marine dinoflagellates Karenia selliformis and Alexandrium ostenfeldii. Currently four gymnodimine analogues are known and characterized. Here we describe a novel gymnodimine and a range of gymnodimine related compounds found in an A. ostenfeldii isolate from the northern Baltic Sea. Gymnodimine D (1) was extracted and purified from clonal cultures, and characterized by liquid chromatographyetandem mass spectrometry (LCeMS/MS), nuclear magnetic resonance (NMR) spectroscopy, and liquid chromatographyehigh resolution mass spectrometry (LC eHRMS) experiments. The structure of 1 is related to known gymnodimines (2e5) with a six-membered cyclic imine ring and several other fragments typical of gymnodimines. However, the carbon chain in the gymnodimine macrocyclic ring differs from the known gymnodimines in having two tetrahydrofuran rings in the macrocyclic ring.

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Section: Biosynthesismentioning

confidence: 99%

Identification of gymnodimine D and presence of gymnodimine variants in the dinoflagellate Alexandrium ostenfeldii from the Baltic Sea

Harju

Koskela

Kremp

et al. 2016

Toxicon

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“…Tetrahydrofuran ring was formed by Baldwin's rules of molecular open-loop and close-loop response by 5-exo-tet cyclization [20], [21], [22], [23].…”

Section: Semisynthesis Of 20(s)-ocotillol-type Saponinsmentioning

confidence: 99%

Discovery, semisynthesis, biological activities, and metabolism of ocotillol-type saponins

Liu

Yang

et al. 2017

Journal of Ginseng Research

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Ocotillol-type saponins are one kind of tetracyclic triterpenoids, sharing a tetrahydrofuran ring. Natural ocotillol-type saponins have been discovered in Panax quinquefolius L., Panax japonicus, Hana mina, and Vietnamese ginseng. In recent years, the semisynthesis of 20(S/R)-ocotillol-type saponins has been reported. The biological activities of ocotillol-type saponins include neuroprotective effect, antimyocardial ischemia, antiinflammatory, antibacterial, and antitumor activities. Owing to their chemical structure, pharmacological actions, and the stereoselective activity on antimyocardial ischemia, ocotillol-type saponins are subjected to extensive consideration. In this review, we sum up the discovery, semisynthesis, biological activities, and metabolism of ocotillol-type saponins.

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“…Much effort has been directed at overturning the kinetic preference in single epoxide-opening events, and subsequently toward extending iterative methods to the more complex polyepoxide cascade openings 41 . With a focus on methods for the assembly of fused tetrahydropyrans (THPs), many have found that inclusion of alkenyl, alkynyl, alkyl or silyl groups pendant to the cleaved epoxides is required to stabilize the partial positive charge that develops in the endo transition state [42][43][44][45][46] .…”

Section: Overturning Chemical 'Rules'mentioning

confidence: 99%

Lessons and revelations from biomimetic syntheses

2011

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Biomimetic synthesis describes the field of organic chemistry that aims to emulate the natural, biosynthetic processes toward natural products. As well as providing insight into how molecules are formed in nature, the benefits of this approach to total synthesis are numerous and extend beyond the gains typical of traditional synthesis. For example, using biosynthetic proposals to design a synthetic route can highlight alternative methods to the desired target. The pursuit of biomimetic syntheses also promotes the development of new reactions to prove or disprove a biosynthetic proposal or to unravel mechanistic implications of a proposed biosynthesis and can lead to the identification of new natural products. Here we look at some recent compelling examples and examine how biomimetic synthesis has led to the discovery of new procedures and principles that would not have been found by other approaches.

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Synthesis of Marine Polycyclic Polyethers via Endo-Selective Epoxide-Opening Cascades

Cited by 81 publications

References 165 publications

Identification of gymnodimine D and presence of gymnodimine variants in the dinoflagellate Alexandrium ostenfeldii from the Baltic Sea

Identification of gymnodimine D and presence of gymnodimine variants in the dinoflagellate Alexandrium ostenfeldii from the Baltic Sea

Discovery, semisynthesis, biological activities, and metabolism of ocotillol-type saponins

Lessons and revelations from biomimetic syntheses

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