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.
Structure and reactivity of lithium diisopropylamide (LDA). The consequences of aggregation and solvation during the metalation of an N,N-dimethylhydrazone
作者:Angela S. Galiano-Roth、David B. Collum
DOI:10.1021/ja00199a042
日期:1989.8
US9673030B2
申请人:——
公开号:US9673030B2
公开(公告)日:2017-06-06
Structure and reactivity of lithium diisopropylamide (LDA) in hydrocarbon solutions. Formation of unsolvated ketone, ester, and carboxamide enolates
作者:Yong Joo Kim、Max P. Bernstein、Angela S. Galiano Roth、Floyd E. Romesberg、Paul G. Williard、David J. Fuller、Aidan T. Harrison、David B. Collum
DOI:10.1021/jo00014a019
日期:1991.7
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.
NMR studies of a ternary complex reagent of lithium ester enolate, chiral diether, and lithium diisopropylamide in an asymmetric Michael reaction
A ternary complex reagent of lithium ester enolate–chiral diether–lithium diisopropylamide was formed in an equimolar mixture of these reagents in toluene based on low-temperature NMR spectroscopy. The use of [6Li,15N]-lithium diisopropylamide as a lithiodeprotonation and complexing reagent produced two sets of doublet peaks in 6Li NMR of a 1:1:1 mixture of lithium enolate–chiral diether–lithium diisopropylamide
根据低温NMR光谱,在甲苯中的这些试剂的等摩尔混合物中形成了烯醇锂酯-手性二醚-二异丙基锂酰胺的三元复合试剂。[ 6 Li,15 N]-二异丙基氨基锂作为硫代去质子化和络合剂的使用在烯醇酸锂-手性二醚-二异丙基氨基锂的1:1:1混合物的6 Li NMR中产生了两组双峰。三元复合试剂。