Studies on The Synthesis of Sesquiterpenes as Host-specific Phytotoxins Directed towards Novel Insecticides.

寄主特异性真菌产生的植物毒素的研究对于阐明其作用机制和开发新的杀虫剂具有重要意义。然而，这些致病毒素的数量不足以进行生物学研究，因为它们从自然来源中获得的数量不多。本项目的目标是合成这些致病性倍半萜的天然异构体及其类似物，以提供大量的光学纯形式用于生物学研究。采用面包酵母不对称还原法，经20步反应，以8.4%的总收率合成了产孢素-AO 1（13-脱氧酚烯酮）。该方法的建立，为进一步研究和开发具有致病性的艾里莫芬烷型倍半萜类化合物提供了一条有效途径。由此得到了乌藨子烯酮、表乌藨子烯酮、非洛地酮、菜豆酮及其类似物。利用这些样品，生物学研究正在进行，初步实验表明，即使差向异构体也具有天然异构体的60-70%的活性。进一步的研究可能揭示这些倍半萜类化合物作为植物病原菌和真菌产孢物质的生物学意义。

Studies on phytotoxins produced by host-specific fungi againdt plants have been paid much attention to clarify the mode of action as well as to develope new insecticides. The amount of these pathogenic toxins, however, not sufficient for biological study, because they are not much available from natural sources. The target of this project is the synthesis of these pathogenic sesquiterpenes to afford natural isomers and their analogs in optically pure forms in substantial amount for biological study.Starting from the hydroxyester with 98.4% e.e. prepared by the asymmetric reduction with bakers yeast, chiral synthesis of sporogen-AO 1( 13-desoxyphomenone ) was achieved in overall 8.4 % yield through 20 steps. By the establishment of this efficient method, general route to afford these pathogenic eremophilane sesquiterpenes was explored. Thus, gigantenone, epi-gigantenone, phomenone ,phase-olinone and analogs were obtained. Using these samples, biological studies is going on, and preliminary experiment showed that even epimer has 60-70% activity of natural isomers. Further studies may reveal biological meaning of these sesquiterpene as pthogens against plants and as sporogenic substances against fungi.