The reactivity and structure determination of various organolithium reagents are described. First of all, we present the development of 13C enriched internal reference system for diffusion coefficient-formula weight (D-FW) correlation. This technique provides us a useful tool to unambiguously characterize the solution structures of several methyllithium-diamine complexes. It is concluded that methyllithium forms di-solvated dimers with tertiary diamines in solution state. Then, we discuss the characterization of cyclopentyllithium in both solid and solution states. With the aids of various NMR techniques and X-ray crystallography, the aggregation and solvation states of cyclopentyllithium are revealed. Unsolvated cyclopentyllithium is hexameric in solid state and exists as a mixture of hexamer and tetramer in hydrocarbon solvent. In the presence of tetrahydrofuran, it forms a tetrasolvated tetramer in both solution and solid states. After that, the solution characterization of sec-butyllithium is discussed. Small amount of lithium sec-butoxide is found to be present in sec-butyllithium solution and is inevitable. The sec-butoxide forms mixed hexamer and octamer with sec-butyllithium. For amidolithium reagents, we first present the characterization of a dimeric lithium chiral amide derived from (S)-valine in both solid and solution states. Then, the solvation state study of various lithium N-alkylanilides in solid state is discussed. The steric factors of the solvents and the alkyl groups highly affect the solvation and aggregation states of the lithium anilides. After that, the characterization of four chiral diamino diethers synthesized from (S)-valinol or alaninol is presented. At the end, the characterization of mixed aggregates of an alkyllithium reagent and a chiral lithium amide derived from N-ethyl-O-triisopropylsilyl valinol is discussed. These characterizations of alkylllithium and amidolithium in both solid and solution not only further our understanding of organolithium reagents, but also provide us the mechanistic insight of organolithium reactions.
Su, Chi-Cheung,
"Reactivity and Structural Characterization of Alkyllithium and Amidolithium Reagents"
(2014).
Chemistry Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z02Z13WM
