Department of Chemistry and Chemical Biology Baker Laboratory , Cornell University , Ithaca , New York 14853-1301 , United States.
J Am Chem Soc. 2019 Jan 9;141(1):388-401. doi: 10.1021/jacs.8b10364. Epub 2018 Dec 17.
Oxazolidinone-based sodiated enolates (Evans enolates) were generated using sodium diisopropylamide (NaDA) or sodium hexamethyldisilazide (NaHMDS) in the presence of N,N,N',N'-tetramethylethylenediamine (TMEDA), ( R,R)- trans- N,N,N',N'-tetramethylcyclohexanediamine [( R,R)-TMCDA], or ( S,S)-TMCDA. C NMR spectroscopic analysis in conjunction with the method of continuous variations (MCV), x-ray 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 are examined. Stereoselective quaternizations, aldol additions, and azaaldol additions are described.
基于恶唑烷酮的钠盐烯醇化物（埃文斯烯醇化物）是在 N,N,N',N'-四甲基乙二胺 (TMEDA)、(R,R)-反式-N,N,N',N'-四甲基环己二胺[(R,R)-TMCDA]或(S,S)-TMCDA 的存在下，使用二异丙基氨基钠 (NaDA) 或六甲基二硅基胺化钠 (NaHMDS) 生成的。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，烯醇化物为八面体双二胺螯合单体。与烯丙基溴的烷基化的速率和计算研究表明，双二胺螯合单体基过渡态结构。与 NaHMDS、NaDA 或 2,6-二叔丁基苯酚钠盐形成混合二聚体的埃文斯烯醇化物钠盐，其反应性也进行了研究。描述了立体选择性季铵化、羟醛加成和氮杂羟醛加成。
