Exploration of New Methodologies for Construction of Carbocycles their Synthetic Application

我们研究了从(1)无环前体和(2)环前体构建环碳框架的新方法。(1)建立了新的亲核物质，如金属同源烯醇酯，并探索了几种类型的选择性碳-碳成键反应。这些结果可以应用于甾体碳框架的构建，并且我们成功地开发了一种有用的可的松全合成方法，包括引入其侧链的一种简短而有用的方法。此外，还提出了一种构造紫杉烷环体系的有效方法。(2)从1-（tms -甲基）环烷醛及其衍生物开始，研究了涉及阳离子碳骨架重排的单碳环扩张反应。在生成由多个杂原子稳定的碳正离子时，环碳经过选择性重排，得到相应的单碳环放大产物，产率高。此外，对不对称取代底物的反应进行了研究，证明了取代基的迁移倾向顺序为：sp^2碳> - sp^3碳> - sp@> - D13@> - d1碳。

We have investigated on new methodologies for construction of cyclic carbon frameworks either from (1) acyclic precursors and (2) cyclic ones.(1) Generation of new nucleophilic species as metal homoenolates has been established, and several types of selective carbon-carbon bond forming reactions have been explored. These results can be applied for construction of steroidal carbon frameworks, and we succeeded to develop a useful methodology for a total synthesis of cortisone, involving a short and useful method for introduction of its side chain. Further, a useful methodology for construction of taxane ring system has also been developed. (2) Starting from 1-(TMS-methyl)cycloalkanecarbaldehydes and their derivatives, one-carbon ring expansion reactions involving cationic carbon skeleton rearrangement have been investigated. On generating carbocationic species stabilized by several hetero atoms, the ring carbon undergoes rearrangement selectively to afford the corresponding one-carbon ring enlarged products in high yields. Further, reactions of unsymmetrically substituted substrates have been studied, and migratory aptitude of a substituent has been proved as the following order: a sp^2-carbon > a more-substituted sp^3-carbon > a less-substituted sp@>D13@>D1-carbon.