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

这项研究的目的是开发基于α，β-环氧硅烷与亲核试剂反应的新的合成反应。八元碳环的立体专一性结构当γ-丙烯酰基硅烷与乙烯基锂反应时，由乙烯基锂的1，2-加合物Brook重排生成的1，2-二乙烯基环丁二醇中间体发生阴离子氧合重排反应，得到单一的非对映异构体。此外，我们发现了一种更通用的合成碳环的方法，其中包括γ-乙烯基-γ-硅基-γ-内酯，由β-甲氧基碳酰基硅烷与乙烯基锂，与乙烯基硫的反应。α，β-环氧基-β-硅基丙醛的O-硅基氰醇衍生物在烷基化剂存在下与碱的反应α，β-环氧基-β-硅基丙醛的O-硅基氰醇衍生物与强碱如LDA，NHMDS在碘化烷存在下反应得到了2，4-双(硅氧基)-3-丁烯腈的2-烷基衍生物，产率很高。没有得到O-烷基化和4-烷基化产物的事实表明，质子提取/环氧化物开环/Brook重排/烯丙基重排/烷基化等串联过程将以协同方式发生。在反应中使用容易获得的光学活性环氧化物似乎非常有希望构建四元手性中心，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.