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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Total Synthesis Of Bio-Active Natural Products Microcarpalide, Synargentolide A, Jaspine B And Anamarine

Penchalaiah, Kamala 08 1900 (has links) (PDF)
The thesis entitled “Total synthesis of bio-active natural products microcarpalide, synargentolide A, jaspine B and anamarine.” demonstrates the utility of chiral pool tartaric acid as the source in the synthesis of bio-active natural products. The thesis was divided into four sections. Section I of the thesis deals with the enantiodivergent synthesis of microcarpalide from tartaric acid. Microcarpalide is a 10-membered lactone of polyketide origin isolated from the fermentation broths of an unidentified endophytic fungi, found to be weekly cytotoxic to mammalian cells and acts as a microfilament discrupting agent. Stereoselective approach for the synthesis of ()-microcarpalide is described from D- and L-tartaric acids, while enantiodivergent approach for the synthesis of both enantiomers is described from L-tartaric acid using ring closing metathesis as the Scheme 2: Enantiodivergent total synthesis of microcarpalide. In section II of the thesis, stereoselective synthesis of synargentolide A is described. Synargentolide A is a polyhydroxy -lactone, isolated from Syncolostemon argenteus, which was founf to exhibit cytotoxic and antitumor properties. Stereoselective synthesis of synargentolide A was accomplished, starting from L-tartaric acid employing, Keck and Brown allylations and ring closing metathesis, as the key steps. Scheme 3: Stereoselective total synthesis of ()-synargentolide A. Section III of the thesis deals with the synthesis of ()-jaspine B. Pachastrissamine (jaspine B), is an anhydrophytoshingosine derivative, isolated from marine sponges Pachastrissa and Jaspis speces. Pachastrissamine was shown to exhibit cytotoxicity (IC 50 0.01 g/mL) against P388, A549, HT29, and MEL28 cell lines. Enantioselective synthesis of jaspine B is accomplished from L-tartaric acid employing, Keck allylation, acid mediated formation of tetrahydrofuran, and olefin cross metathesis as the key reactions. In section IV of the thesis, enantioselective synthesis of ()-anamarine is described. Anamarine is a polyhydroxy -lactone isolated from the flowers and leaves of Peruvian hyptis, possessing cytotoxicity against human tumor cell lines. Enantioselective synthesis of -anamarine is accomplishedelaboration of hitherto unknown -keto phosphonate derived from tartaric acid amide. In an appendix for the thesis, enantiodivergent synthesis for 4-siloxy-pent-2-enone was described. The usefulness of asymmetric aldol reaction is exemplifiedin this section. hydroxy amide synthesized from crotonaldehyde is suitably elaborated to the diene which on RCM yielded 4-silyloxycyclopent-2-enone. Further synthetic modification of this compound afforded the other enantiomer. Scheme 6: Enantiodivergent synthesis of hydroxy cyclopentenones. (For structural formula pl the abstract pdf file)

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