Stereoselective reactions. 26. Solution structures of chiral bidentate lithium amide in relation to the solvent-dependent enantioselectivities in deprotonation reaction
作者:Daisaku Sato、Hisashi Kawasaki、Ichio Shimada、Yoji Arata、Kimio Okamura、Tadamasa Date、Kenji Koga
DOI:10.1016/s0040-4020(97)00422-5
日期:1997.5
and 15N-NMR spectroscopic analyses of a labeled chiral bidentate lithium amide () have shown that it exists as a chelated monomer (5) in THF and in DME, as a chelated dimer (6) in toluene and in ether, while as a chelated monomer (5) in any of these solvents in the presence of 2 equivalents of HMPA. Solvent-dependent enantioselectivities in deprotonation of 4-tert-butylcyclohexanone (2) by (R)-1 appear
标记的手性二齿氨基锂锂的6 Li和15 N-NMR光谱分析表明,它在THF和DME中以螯合单体(5)的形式存在,在甲苯和乙醚中以螯合二聚物(6)的形式存在,在2当量的HMPA存在下,在任何一种溶剂中作为螯合单体(5)。(R)-1对4-叔丁基环己酮(2)进行质子化的溶剂依赖性对映选择性似乎与这些溶液结构相关。