METAL MEDIATED ASYMMETRIC INTRAMOLECULAR HYDROSILATION

金属介导的不对称分子内氢化硅烷化

• 批准号: 3299829
• 负责人: BRICE BOSNICH
• 金额: $ 14.91万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-04-01 至 1992-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3299829
• 关键词: alkenes; amides; catalyst; conformation; esters; hydrogen bond; ionophores; ketones; macrolide antibiotics; metal complex; rhodium; silicon; stereochemistry; stereoisomer; stoichiometry

The hydration of olefins and the reduction of ketones play an important role in the synthetic strategies for the construction of biologically active molecules. The current methods of hydration of olefins by, for example, hydroboration or oxymercuration and reduction of ketones by, for example, boron or aluminum hydrides are, in the main, stoichiometric transformations. Although many of these reactions have been carried out enantioselectively to produce enantiomeric products, the chemoselectivity is poor in that ester and amide groups are generally reduced in competition. Moreover, there are few examples of asymmetric catalysis. Intramolecular asymmetric catalytic hydrosilation provides an attractive solution to the chemoselective hydration of olefins and the reduction of ketones. This proposal is directed at developing new chiral catlysts for asymmetric catalytic hydrosilation. A mechanistic rationalization is offered which suggests that certain readily available substrates will generate high optical yields by an intramolecular process. The strategy employs familiar concepts of discrimination by preferred cyclic conformations in the enantioseleetive transition sites. The products of hydrosilation are readily converted into optically active 1,4-, 1,3 and 1,2-diols. These diols are key starting materials in the synthesis of macrolide and ionophore antibioties. The proposal is also directed at an important methodological issue. This concerns the problem of selecting the correct catalyst and substrate which will give high optical yields. For this purpose, it is proposed to investigate the mechanism of the reaction in order to determine the origins of the enantioselection. Such studies will provide a basis for the design of catalysts for other transformations.

烯烃的水合和酮的还原起着重要作用 在构建合成策略中发挥着重要作用 生物活性分子。 目前的补水方法 通过例如硼氢化或羟汞化来制备烯烃，以及 通过例如氢化硼或氢化铝还原酮 主要是化学计量变换。 虽然很多 这些反应是对映选择性进行的 产生对映体产物，化学选择性较差 酯基和酰胺基通常在竞争中减少。 此外，不对称催化的例子很少。 分子内不对称催化硅氢化提供了 烯烃化学选择性水合的有吸引力的解决方案 酮的减少。 该提案旨在发展 用于不对称催化硅氢化的新型手性催化剂。 一个 提供了机械合理化，表明某些 容易获得的基板将通过以下方式产生高光学产率 分子内过程。 该策略采用了熟悉的概念 优先循环构象的歧视 对映选择性转变位点。 硅氢化反应的产物很容易转化为光学 活性 1,4-、1,3 和 1,2-二醇。 这些二醇是关键的起始点 合成大环内酯类和离子载体类抗生素的材料。 该提案还针对一个重要的方法问题。 这涉及到选择正确的催化剂和 基板将提供高光学产率。 为此， 建议研究该反应的机理 为了确定对映体选择的起源。 这样的 研究将为其他催化剂的设计提供基础 转变。