名称:
Structure and reactivity of lithium diisopropylamide (LDA) in hydrocarbon solutions. Formation of unsolvated ketone, ester, and carboxamide enolates
摘要:
Enolization of ketones, tert-butyl esters, and carboxamides by solvent-free lithium diisopropylamide (LDA) in hexane or toluene are described. Enolates are isolated as spectroscopically pure, white (often crystalline) solids. Solubilities of the enolates in hexane range from highly soluble to completely insoluble. Enolizations of aldehydes, methyl esters, and acetone afford complex mixtures. Analysis of [Li-6]LDA and [Li-6, N-15]LDA in hexane by Li-6 and N-15 NMR spectroscopy show evidence of an equilibrium mixture of at least three cyclic oligomers.