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
Enantioselective synthesis of β-hydroxy-α-methyl carbonyl compounds by aldol reaction
作者:Akira Ando、Takayuki Shioiri
DOI:10.1016/s0040-4020(01)81078-4
日期:——
The enantioselective aldolreactions of ketone lithium enolates with aldehydes mediated chiral lithium amides were extensively investigated. The chiral amino ethers 4a–4l and diamines 16a,b were prepared from α-amino acids. The reaction conditions and the substituent effects of chiral lithium amides were examined using 4a–4l and 16a,b in the aldolreaction of lithium enolate of 2,2-dimethyl-3-pentanone