Structure-Reactivity Relationships in Carbanion Chemistry

本研究的重点是研究N，N，N‘，N’-四甲基乙二胺(TMEDA)及其相关的二胺如何修饰或不修饰有机锂的聚集体结构和反应活性。核磁共振的结构研究将使用TMEDA和相关的二胺与正丁基锂、苯基锂、乙酰锂和相关的有机锂衍生物。二胺与四氢呋喃和相关的醚类配体的比较和竞争将确定醚类与有机硫竞争或协同结合的情况。定量的配体结合研究将为后续的速率研究奠定热化学基础。在公认的溶液结构指定的背景下，二胺有机锂衍生物的典型反应的速率数据将为深入了解进入限速过渡结构的溶剂化和聚集事件提供洞察。将溶剂化效应分解为基态和过渡态的贡献将是理解TMEDA在有机锂化学中的作用的核心。有机化学和高分子化学项目支持康奈尔大学化学系的戴维·B·科勒姆博士的研究。科勒姆教授将专注于挑战现有的关于N，N，N‘，N’-四甲基乙二胺(TMEDA)和相关二胺如何影响有机锂结构和反应性的概念。由于有机锂试剂的广泛使用，这项研究对有机合成具有重要的意义。

The focus of this research is the investigation of how N,N,N',N'-tetramethylethylenediamine (TMEDA) and related diamines modify, or fail to modify, organolithium aggregate structures and reactivity. Structural studies with NMR will use TMEDA and related diamines with n-butyllithium, phenyllithium, lithium acetylides and related organolithium derivatives. Comparisons and competitions of diamines with tetrahydrofuran and related ethereal ligands will ascertain the circumstances under which the ethers bind competitively or cooperatively to organolithiums. Quantitative ligand binding studies will establish thermochemical foundations for subsequent rate studies. Rate data for representative reactions of diamine-solvated organolithium derivatives, in the context of well-established solution structure assignments, will afford insights into the solvation and aggregation events proceeding to the rate limiting transition structures. Dissection of solvation effects into ground state and transition state contributions will be central to an understanding of TMEDA's role in organolithium chemistry. With this renewal award, the Organic and Macromolecular Chemistry Program is supporting the research of Dr. David B. Collum of the Department of Chemistry at Cornell University. Professor Collum will focus his work on challenging the existing notions on how N,N,N',N'-tetramethylethylenediamine (TMEDA) and related diamines influence organolithium structures and reactivities. The research has substantial implications for organic synthesis due to the wide spread use of organolithium reagents.