Synthesis of Optically Active δ-Lactones by Rearrangement Reactions

如今，新反应的发现在有机化学中是一件非常罕见的事情--然而，幸运的是，它最近发生在我们身上。这个场合是这个项目的基础：在催化量的氰化钾存在下，1-羟基-2-环戊酮羧酸酯重排成δ-戊内酯衍生物。后者是天然产物和具有相关生物活性的合成化合物的突出结构基序。在这个项目中，我们希望将该反应进一步发展为对映选择性方法。我们正在采取两种策略：在第一个项目中，我们计划通过在起始材料中引入额外的立体中心来控制产品中新立体中心的配置。然而，该项目的主要和第二部分是开发一种手性有机催化剂，该催化剂允许对映选择性转化为δ-内酯。一方面，计划利用金鸡纳生物碱制备光学活性奎宁环鎓氰化物并将其用作催化剂。此外，我们将研究手性铵盐作为催化剂，这是基于反式-1，2-二氨基环己烷骨架。新方法的潜力将在第三个项目中得到证明，即天然产物诃子酸和一些昆虫信息素的立体选择性全合成。

Nowadays, the discovery of a new reaction is a very rare event in organic chemistry – and yet it has fortunately happened to us recently. This occasion is the basis for this project: In the presence of a catalytic amount of potassium cyanide 1-hydroxy-2-cyclopentanone carboxylic esters rearrange into δ-valerolactone derivatives. The latter is a prominent structural motif of natural products and synthetic compounds with relevant biological activity. In this project we would like to develop the reaction further into an enantioselective method. We are pursuing two strategies: In a first project, we are planning to control the configuration of the new stereocenter in the product by introducing an additional stereocenter into the starting material. The main and second part of this project, however, is the development of a chiral organocatalyst that allows for an enantioselective transformation to the δ-lactones. On the one hand, it is planned to use cinchona alkaloids to prepare optically active quinuclidinium cyanides and to use them as catalysts. Furthermore, we will investigate chiral ammonium salts as catalysts which are based on the trans-1,2-diaminocyclohexane scaffold. The potential of the new methodology will then be demonstrated in a third project in the stereoselective total synthesis of the natural product chebulic acid and some insect pheromones.