Structures and Reactivities of Sodiated Evans Enolates: Role of Solvation and Mixed Aggregation on the Stereochemistry and Mechanism of Alkylations
作者:Zirong Zhang、David B. Collum
DOI:10.1021/jacs.8b10364
日期:2019.1.9
crystallography, and density functional theory (DFT) computations revealed the enolates to be octahedral bis-diamine-chelated monomers. Rate and computational studies of an alkylation with allyl bromide implicate a bis-diamine-chelated-monomer-based transition structure. The sodiated Evans enolates form mixed dimers with NaHMDS, NaDA, or sodium 2,6-di- tert-butylphenolate, the reactivities of which
在 N,N,N',N'-四甲基乙二胺 (TMEDA)、(R,R)-反式-存在下,使用二异丙基酰胺钠 (NaDA) 或六甲基二硅肼钠 (NaHMDS) 生成基于恶唑烷酮的钠化烯醇化物 (Evans enolates) N,N,N',N'-四甲基环己二胺 [(R,R)-TMCDA] 或 (S,S)-TMCDA。13C NMR 光谱分析结合连续变化法 (MCV)、X 射线晶体学和密度泛函理论 (DFT) 计算表明烯醇化物是八面体双二胺螯合单体。烯丙基溴烷基化的速率和计算研究表明基于双二胺螯合单体的过渡结构。钠化的 Evans 烯醇化物与 NaHMDS、NaDA 或 2,6-二叔丁基苯酚钠形成混合二聚体,检查其反应性。