Synthetic Studies Towards Diterpene Plumisclerin A And Macrolide Cyanolide A

This thesis is mainly focused on synthetic studies of diterpene plumisclerin A and macrolide cyanolide A. It consists of the following two parts:Chapter1. Synthetic studies towards diterpene plumisclerin A.Plumisclerin A, a diterpene possessing a novel carbon skeleton incorporating a tricyclo[4,3,1,01,5]decane ring, displayed in vitro cytotoxicity against selected cancer cell lines. A concise illustration of the isolation, biological activity, structure identification and biomimetic synthesis background of diterpene plumisclerin A is described. A key reaction precursor for total synthesis of plumisclerin A, i.e.,1-29(a bicyclo dicarbonyl compound) has been synthesized in6steps (for the longest linear sequence) from the commercially material1-22[ethyl2-oxo-2-(2-oxocyclohexyl) acetate], which featured an acid-catalyzed Nazarov cyclization as a key transformation. However, the attempt of SmI2-mediated6-exo-trig cyclization was not successful.Chapter2. Synthetic studies towards macrolide cyanolide ACyanolide A, a dimeric glycosidic macrolide consisting of a central16-membered macrocycle fused to both tetrahydropyrans and two xylose residues, and it showed significant molluscicidal activity against biomphalaria glabrata. A brief introduction of the isolation, structure identification, and biological activity of cyanolide A were is described, and relevant synthetic research of cyanolide A has been systematically summarized. A key precursor for the synthesis of macrolide cyanolide A, i.e., compound2-84(an enol silyl ether), has been synthesized from known (rac)-1-hexen-4-o1(2-88) by utilizing an SN2reaction and a Horner-Wadsworth-Emmons olefination as key transformations. Due to the tremendous difficulty associated with the preparation of2-84and the intrinsic instability of this intermediate, the subsequent key double hetero-Diels-Alder reaction has never been attempted yet.