Development of new synthetic reactions based on the reactions of α, β-epoxysilanes and nucleophiles

本研究的目的是在α， β-环氧硅烷与亲核分子反应的基础上，开发新的合成反应。八元碳环的立体定向结构用乙烯基锂处理γ-丙烯酰基硅烷时，通过对乙烯基锂的1,2 -加合物Brook重排生成的1,2 -二乙烯基环丁二醇中间体进行阴离子氧- cope重排，得到环烯酮衍生物为单一的非对映体。此外，我们还发现了一种更通用的合成碳环的方法，即由β-甲氧基羰基酰基硅烷与乙烯基锂和乙烯基锂反应制备γ-乙烯基-γ-硅基-γ-内酯。α、β-环氧-β-硅基丙烷衍生物在烷基化剂存在下与碱反应α、β-环氧-β-硅基丙烷衍生物与强碱如LDA、NHMDS在碘化烷基存在下反应，得到2-烷基化的2,4 -二（硅氧基）-3-丁腈衍生物，收率高。没有得到o -烷基化和4-烷基化产物，说明质子抽离/环氧环开环/布鲁克重排/烯丙基重排/烷基化的串联过程是协同发生的。在反应中使用易于获得的光学活性环氧化物似乎很有希望构建季手性中心，这将是进一步研究的主题。

The objective of this study has been to develop new synthetic reactions based on the reaction of α, β-epoxysilanes with a nucleophile.1. Stereospecific Construction of Eight-Membered CarbocyclesWhen γ-acryloylacylsilane was treated with vinyllithium, a cyclooctenone derivative was obtained as a single diastereomer via an anionic oxy-Cope rearrangement of 1, 2-divinylcyclobutanediol intermediate generated by way of Brook rearrangement of the 1, 2-adduct of the vinyllithium. Furthermore, we found a more versatile methodology for the synthesis of the carbocycles, which involves the reaction of γ-vinyl-γ-silyl-γ-lactones, prepared from β-methoxycarbonyacylsilane with vinyllithium, with vinyllithium.2. Reaction of O-silyl Cyanohydrin derivatives of α, β-Epoxy-β-silylpropanal with Bases in the Presence of Alkylating AgentsReaction of O-silyl cyanohydrin derivatives of α, β-Epoxy-β-silylpropanal with a strong base such as LDA, NHMDS in the presence of alkyl iodide afforded 2-alkylated derivatives of 2, 4-bis (siloxy)-3-butenenitrile as a single isomer in excellent yields. The fact that no O-alkylated and 4-alkylated products were obtained suggests that the tandem processes involving proton abstraction/epoxide ring opening/Brook rearrangement/allylic rearrangement/alkylation would occur in a concerted manner. The use of readily available optically active epoxides in the reaction seems very promising for construction of quaternary chiral centers and will be the subject of further studies.