Asymmetric Synthesis Using Acetals : Formation of Chiral Oxonium Ion

研究了烯缩醛分子内卤代醚化反应生成手性氧鎓离子中间体及其应用，并以3-（1，4-环己二烯-3-基）丙醛与手性氢化苯偶氮化合物环己二烯缩醛分子内卤代醚化反应生成手性非外消旋环己烯缩醛为例，开展了百部生物碱的合成工作。结果，9 α-表-斯泰宁已经实现，斯泰宁本身的合成已进入最后阶段。从它们的合成中间体出发，合成了具有N-Smase抑制活性的scyphostatin的环氧环己烯酮核心，并发现了无环σ-对称二烯缩醛的意外多米诺分子内卤代醚化反应，一锅法合成了具有四个不对称中心的四氢呋喃。

Formations of chiral oxonium ion intermediates by intramolecular haloetherification of ene acetals and their applications have been investigated.As an application of the chiral, non-racemic cyclohexene acetal obtained by an intramolecular haloetherification reaction of cyclohexadiene acetal from 3-(1,4-cyclohaxadien-3-yl)propanal and chiral hydrohenzoin, synthetic work of stemona alkaloids was held. As a result, 9a-epi-stenine has been achieved, and the synthesis of stenine itself is on the last stage. From the intermediate of their syntheses, the epoxy cyclohexenone core of scyphostatin having N-Smase inhibiting activity was synthesized.Furthermore, an unexpected domino intramolecular haloetherification reaction of acyclic σ-symmetic diene acetals was found, and the tetrahyderofurans having four asymmetric centers were obtained in one-pot operation.