Fine Modification of Salen Ligands - Effects on the Salen-Ti-Catalyzed Asymmetric Cyanosilylation of Aldehydes
作者:Chengwei Lv、Qigan Cheng、Daqian Xu、Shoufeng Wang、Chungu Xia、Wei Sun
DOI:10.1002/ejoc.201100319
日期:2011.7
bifunctional N-oxide salen―Ti IV complexes and a pyrrolidine salen―Ti IV complex in combination with achiral N-oxide were developed and applied to the asymmetricaddition of trimethylsilyl cyanide to aldehydes. Notably, both enantiomers of trimethylsilyl ethers of cyanohydrins could be easily prepared by modifying the catalysts employed in this reaction, which are based on the same chiral diamine collar
开发了新的双功能 N-氧化物 salen-Ti IV 配合物和吡咯烷 salen-Ti IV 配合物与非手性 N-氧化物的结合,并将其应用于三甲基氰基氰化物与醛的不对称加成。值得注意的是,氰醇的三甲基甲硅烷基醚的两种对映异构体都可以通过修改该反应中使用的催化剂来轻松制备,这些催化剂基于相同的手性二胺环,源自 L-酒石酸。通过使用相对低的催化剂负载量和仅 1.05 当量的三甲基氰基氰化物 (TMSCN),通常以中等至良好的对映体过量和优异的产率获得产物。
A practical Ti-salen catalyst based on dimeric salen ligand for asymmetric addition of trimethylsilyl cyanide to aldehydes
作者:Chengwei Lv、Daqian Xu、Shoufeng Wang、Cheng-Xia Miao、Chungu Xia、Wei Sun
DOI:10.1016/j.catcom.2011.04.022
日期:2011.7
from L-tartaric acid was synthesized through linking two salen units with 1,6-dibromohexane. The corresponding Ti complex was proved to be an efficient catalyst for asymmetric addition of trimethylsilyl cyanide to aldehydes, providing the corresponding optically active trimethylsilyl ether of cyanohydrins with moderate to good enantiomeric excesses and excellent yields under relatively low catalyst
Dismantling the salen framework: design of new asymmetric silylcyanation catalysts
作者:Jérémy Ternel、Pascal Roussel、Francine Agbossou-Niedercorn、Régis M. Gauvin
DOI:10.1039/c2cy20818k
日期:——
A series of novel chiral phenoxyimine Al(III) complexes catalyzes asymmetric addition of SiMe3CN to a broad range of aldehydes with high yields and good to excellent enantioselectivities in the presence of a Lewis base.
Proline adducts of metallo-organic, sextuply-stranded lanterns as homogeneous catalysts for asymmetric catalysis
作者:Wenting Zhu、Xiao Wu、Cheng He、Chunying Duan
DOI:10.1016/j.tet.2013.09.076
日期:2013.12
incorporating a L or D-pyrrolidine moiety within the respective ligands. The Ce-Pro1 complexes are comprised of chiral pyrrolidine-containing ligands and have lantern-like cavities. They function as asymmetric catalysts that promote cyanosilylation reactions with good conversions and enantioselectivity.
两个纯手性的金属-有机,sextuply链的,灯笼状复合物,CE-大号- Pro1的和CE- d - Pro1的,分别通过自组装通过将合成的大号或d的各自的配体-吡咯烷内部分。在CE- Pro1的复合物由含有手性吡咯烷配体和具有灯笼状腔。他们作为促进具有良好的转化率和对映选择性硅氰化反应不对称的催化剂。
Enantioselective Silylcyanation of Aldehydes and Ketones by a Titanium Catalyst Prepared from a Partially Hydrolyzed Titanium Alkoxide and a Schiff Base Ligand
作者:Kazuhiko Yoshinaga、Takushi Nagata
DOI:10.1002/adsc.200900207
日期:2009.7
base ligand, the enantioselective silylcyanation of aldehydes and ketones proceeded in a short reaction time at room temperature to afford the corresponding optically active cyanohydrinderivatives in excellent chemical yield with high enantiomeric excess (86–97% ee). The results indicate that partially hydrolyzed titanium alkoxides are a promising titanium source for the preparation of efficient catalysts