Synthetic Studies of Bioactive Marine Natural Products using Intramolecular Reaction

1. Kalihinane型二萜化合物Kalihinene X和Kalihinol A的合成研究Kalihinane型二萜化合物具有顺式或反式十氢萘和四氢吡喃或四氢呋喃作为其基本骨架，是一种高度官能化的海洋二萜化合物，带有异氰基、异硫氰基、甲酰胺、羟基和/或氯基团。Kalihinene X是具有顺式萘烷和氯化四氢吡喃部分的Kalihinane型二萜甲酰胺。Kalihinol A是具有反式萘烷和氯化四氢吡喃部分的Kalihinane型二萜异氰化物。为了高效合成这两种化合物，通过共同的合成中间体顺式-十氢萘衍生物进行合成。通过烷基砜的碳负离子与环氧醇的区域选择性偶联反应和分子内Diels-Alder反应合成常用的合成中间体顺式十氢萘衍生物，全合成了kalihinene X。通过全合成确定了kalihinene X的绝对构型。2.海洋萜类化合物Elisabethin C和Elisapterosin B的合成研究Elisabethin C是从柳珊瑚Pseudopterogorgia elisabethae中分离得到的一种新的双环双降二萜化合物。Elisapterosin B是从柳珊瑚中分离得到的一个新的四环二萜类化合物。为了有效合成这两种化合物，通过共同的合成中间体双环[4.3.0]壬烷衍生物进行合成。以双环[4.3.0]壬烷衍生物为合成中间体，以Dieckmann环合为关键步骤，立体选择性合成了伊丽莎白辛C。在此基础上确定了伊丽莎白辛C的绝对构型。将双环[4.3.0]壬烷衍生物转化为三环化合物，其是elisapterosin B的合成前体。

1.Synthetic Studies on Kalihinane-type Diterpenoid Kalihinene X and Kalihinol A.Kalihinane-type diterpenoid possessing cis-or trans-decalin and tetrahydropyran or tetrahydrofuran as its fundamental skeleton, is a highly functionalized marine diterpenoid, bearing isocyano, isothiocyanato, formamide, hydroxy and/or chlorine groups. Kalihinene X is a kalihinane-type diterpene formamide having cis-decalin and chlorinated tetrahydropyran moieties. Kalihinol A is a kalihinane-type diterpene isocyanide having trans-decalin and chlorinated tetrahydropyran moieties. For efficient synthesis of both compounds, the synthesis was carried out through common synthetic intermediate cis-decalin derivative. Total synthesis of kalihinene X involves regioselective coupling reaction of carbanion of alkyl sulfone with epoxyalcohol and synthesis of common synthetic intermediate cis-decalin derivative by intramolecular Diels-Alder reaction. The absolute configuration of kalihinene X could be determined by this total synthesis. The cis-decalin derivative was converted to trans-decalin derivative which is synthetic precursor of kalihinol A.2.Synthetic Studies on Marine Terpenoid Elisabethin C and Elisapterosin B.Elisabethin C is a novel bicyclic bisnor-diterpenoid which was isolated from the gorgonian Pseudopterogorgia elisabethae. Elisapterosin B is a novel tetracyclic diterpenoid which was isolated from the same gorgonian. For efficient synthesis of both compounds, the synthesis was carried out through common synthetic intermediate bicyclo[4.3.0]nonane derivative. Total synthesis of elisabethin C was successfully carried out by stereoselective synthesis of bicyclo[4.3.0]nonane derivative, which is the common synthetic intermediate, with Dieckmann cyclization as the key step. The absolute configuration of elisabethin C was determined based on this total synthesis. The bicyclo[4.3.0]nonane derivative was converted to tricyclic compound which is synthetic precursor of elisapterosin B.