Synthetic Studies of Bioactive Marine Natural Products using Intramolecular Reaction

1.Kalihinane-型二萜类化合物Kalihinene X和Kalihinol A的合成研究Kalihinane-型二萜类化合物以顺式或反式十氢萘和四氢吡喃或四氢呋喃为基本骨架，是一种高度官能化的海洋二萜类化合物，含有异氰基、异硫氰酸基、甲酰胺、羟基和/或氯基。Kalihinene X是一种Kalihinane类型的二萜甲酰胺，含有顺式十氢萘和氯化四氢吡喃部分。Kalihinol A是一种卡利辛烷型二萜异氰化物，含有反式十氢萘和氯化四氢吡喃部分。为了有效地合成这两种化合物，通过常见的合成中间体顺式十氢萘衍生物进行了合成。Kalihinene X的全合成包括烷基砜的碳负离子与环氧醇的区域选择性偶联反应，以及通过分子内Diels-Alder反应合成常见的合成中间体顺式十氢萘衍生物。通过这种全合成，可以确定卡利欣X的绝对构型。将顺式十氢化衍生物转化为反式十氢化衍生物，即海参油素A的合成前体化合物。海产萜类化合物香豆素C和香豆素B的合成研究。香豆素C是从柳珊瑚中分离得到的一个新的双环二萜类化合物。Elisapterosin B是从同一柳珊瑚中分离得到的一个新的四环二萜类化合物。为了有效地合成这两种化合物，通过常见的合成中间体双环[4.3.0]正庚烷衍生物进行合成。以Dieckmann环化反应为关键步骤，通过立体选择性合成常用的合成中间体双环[4.3.0]壬烷衍生物，成功地实现了灯盏花素C的全合成。在全合成的基础上确定了灯盏花素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，合成了香豆素B的合成前体化合物。

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.