SYNTHETIC STUDY ON ANTIFEEDANT OF INSECTS AND RELATED COMPOUNDS

印楝素的合成研究：印楝素属于一类柠檬苦素类化合物，对昆虫具有拒食和生长抑制活性。尽管许多合成化学家一直在尝试合成该分子，但由于其非常复杂的结构，尚未有全合成的报道。今年，我们发现分子内饮食-Alder反应和脱羧基-Claisen重排有效地构建了A环上的五个不对称中心。经过几步反应，合成了一个简单的环戊烷环取代三环的模型化合物，并对自由基环化反应进行了研究。反应顺利地进行了成套带来。与其他文献报道的方法相比，这种方法使得全合成时间更短、效率更高。另一种化合物：除印楝素外，还利用新开发的分子内脱羧基Robinson环合成了有望显示昆虫拒食活性的维拉酮，该环能够构建该分子的双环体系。

In the final year, the following researches were carried out.Synthetic study on azadirachtin : Azadirachtin belongs to a class of limonoid which shows antifeeding and growth-inhibitory activities to insects. Although many synthetic chemists have been trying to synthesize the molecule, no total synthesis was reported due to the very complicated structure. This year, we have found that intramolecular Diets-Alder reaction followed by decarboxylation-Claisen rearrangement proceeded efficiently to construct the five asymmetric centers on A-ring. After several steps, a model compound, which possessed a simple cyclopentane ring instead of tricyclic moiety, was prepared and radical cyclization was investigated. The reaction proceeded suite smoothly to form Bring. This approach enables the shorter and more efficient total synthesis than those reported by other groups.Anther compound : In addition to azadirachtin, velamone, which is expected to exhibit the insect antifeedant activity, was synthesized by employing a newly developed intramolecular decarboxylative Robinson annulation which enabled the construction of bicyclic system of the molecule.