Stereoselective Reactions. 25. Enantioselective Deprotonation of Prochiral 4-Substituted Cyclohexanones by Chiral Chelated Lithium Amides
作者:Ryuichi Shirai、Daisaku Sato、Kazumasa Aoki、Masahide Tanaka、Hisashi Kawasaki、Kenji Koga
DOI:10.1016/s0040-4020(97)00288-3
日期:1997.4
4-substituted cyclohexanones (4a∼d) by chiral chelated lithium amides (8a≈k) in the presence of excess trimethylsilyl chloride was realized to give the corresponding chiral silyl enol ethers (6a∼d) in up to 89% ee. It is shown that enantioselectivity of the reaction is dependent on the solvent used, but becomes almost independent on the solvent in the presence of HMPA. The sense of asymmetric induction
在过量的三甲基甲硅烷基氯存在下,通过手性螯合锂酰胺(8a≈k)对前手性4-取代的环己酮(4a〜d)进行对映选择性去质子化反应,得到相应的手性甲硅烷基烯醇醚(6a〜d)的比例高达89% ee。结果表明,反应的对映选择性取决于所用的溶剂,但在HMPA存在下,其对映选择性几乎与溶剂无关。不对称诱导的感觉可以与锂酰胺的手性碳在带有手性碳的酰胺氮上的构型相关。©1997爱思唯尔科学有限公司。