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
Asymmetric addition of n-butyllithium to aldehydes: new insights into the reactivity and enantioselectivity of the chiral amino ether accelerated reaction
作者:Johan Granander、Richard Sott、Göran Hilmersson
DOI:10.1016/s0040-4020(02)00378-2
日期:2002.6
Enantioselective butylation of benzaldehyde with n-butyllithium was mediated by a series of chiral lithium amide analogues to give 1-phenylpentanol in good to moderate enantioselectivities. In order to achieve high enantiomeric excess in the reaction, the lithium amide must have a substituent larger than methyl on both the carbon at the stereogenic center and the nitrogen. Computational studies, using
Aggregation Studies of Complexes Containing a Chiral Lithium Amide and <i>n</i>-Butyllithium
作者:Deyu Li、Chengzao Sun、Jia Liu、Russell Hopson、Weibin Li、Paul G. Williard
DOI:10.1021/jo702655m
日期:2008.3.1
and 15N NMR, and other 2D NMR techniques. A mixed 2:1 trimeric complex was identified as the major species as the stoichiometry approached 1.5 equiv of n-BuLi to 1 equiv of amine compound. 1H and 13C INEPT DOSY spectra confirmed this lithium aggregate in the solution. The formula weight of the aggregate, correlated with diffusion coefficients of internal references, indicated the aggregation number
由手性氨基化锂的一种系统和Ñ正丁基锂在tol- d 8与溶液进行了研究1 H和13 ÇINEPT DOSY,6 Li和15 ÑNMR,和其他2D NMR技术。当化学计量接近1.5当量的n- BuLi对1当量的胺化合物时,混合的2∶1三聚体配合物被鉴定为主要种类。1 H和13 C INEPT DOSY光谱证实了该锂聚集在溶液中。骨料的配方重量与内部参照物的扩散系数相关,表明该配合物的骨料数量。对数D rel的图vs log FW是线性的(r > 0.9900)。6 Li和15 N NMR滴定实验也证实了这些结果。这些NMR实验表明,这种混合的聚集体是负责将n- BuLi不对称加成到醛中的物质。
Mixed Aggregates Containing <i>n</i>-Butyl-, <i>sec</i>-Butyl-, or <i>tert</i>-Butyllithium and a Chiral Lithium Amide Derived from <i>N</i>-Isopropyl-<i>O</i>-methyl Valinol
作者:Paul G. Williard、Chengzao Sun
DOI:10.1021/ja972277d
日期:1997.12.1
ANDO, AKIRA;SHIOIRI, TAKAYUKI, TETRAHEDRON, 45,(1989) N6, C. 4969-4988