Synthetic Studies of Cotylenol, Having Plant Growth Activity, and the Related Biogenetically Active Terpenoids.

1.从其同系物羟基环芳烃(2)中生物合成了一种二萜类化合物，命名为sordaricin(1)。从1和2之间的结构关系来看，1的生物发生必须包括2的中心8元环的氧化环分裂，然后是环戊二烯和不饱和醛部分的分子内Diels-Alder反应。利用该Diels-Alder反应进行的合成研究首次完成了1.2甲酯衍生物的全合成。完成了5-8-5元三环二萜-2，5-二烯(3)的全合成。虽然3尚未分离，但已有多个萜类化合物从3中生物合成。侧柏内酯A和B(4，5)分别是3和倍半萜内酯的Diels-Alder产物，分别为双叶内酯(6)和双叶内酯(7)。事实上，3与全合成的6和7之间的Diels-Alder反应分别得到了4和5，具有很高的立体选择性。在全合成的基础上，推导出了4和5的绝对构型。在8，9-乙二醇基的立体化学控制中，存在着全合成子叶醇(8)的合成问题。为了解决这个问题，我们研究了两条合成路线。尽管Dial前体的还原环化反应不能控制乙二醇功能的立体化学，但烯环化过程得到了一些令人鼓舞的结果。后者不仅提供了控制立体化学的方法，而且提供了将与8的不稳定性密切相关的3-羟基转化为硫醇部分的方法。

1. It has been proved that a diterpenoid named sordaricin (1) is biosynthesized from its congener, hydroxycycloaraneosene (2). From the structural relationships between 1 and 2, the biogenesis of 1 must involve an oxidative ring-fission of the central 8-membered ring of 2 followed by an intra-molecular Diels-Alder reaction of resulted cyclopentadiene and unsaturated aldehyde moieties. The synthetic studies utilizing of this Diels-Alder reaction have accomplished the first total synthesis of methyl ester derivative of 1.2. The total synthesis of fusicocca-2,5-diene (3), a 5-8-5-membered tricyclic diterpene, has been accomplished. Although 3 has not been isolated yet, several terpenoids are considered to be biosynthesized from 3. Plagiospilolides A and B (4,5), metabolites of the liverwort, are the Diels-Alder products from 3 and the sesquiterpene lactones, diplophyllolide (6) and diplophyllin (7), respectively. In fact, the Diels-Alder reactions between 3 and totally synthesized 6 and 7 gave 4 and 5, respectively, with high stereoselectivities. With this total synthesis, the absolute configurations of 4 and 5 have been deduced.3. A synthetic problem for the total synthesis of cotylenol (8) laid in the control of the stereochemistry of an 8,9-glycol moiety. To overcome this problem, two synthetic routes were investigated. Although the reductive cyclization of dial-precursors failed to control the stereochemistries of this glycol function, the 'ene'-cyclization procedure gave several encouraging results. The later process has provided not only the method of controlling the stereochemistries but also the method of converting 3-hydroxyl group, which is deeply related with an instability of 8, to a thiol moiety.