Synthesis of novel carbohydrate-based valine-derived formamide organocatalysts by CuAAC click chemistry and their application in asymmetric reduction of imines with trichlorosilane
作者:Xin Ge、Chao Qian、Xinzhi Chen
DOI:10.1016/j.tetasy.2014.10.003
日期:2014.11
organocatalysts combining carbohydrate and N-formyl-l-valine derivatives were prepared by CuII-catalyzed diazotransfer and CuI-catalyzed azide–alkyne 1,3-dipolar cycloaddition CuAACclickchemistry. It was found that the carbohydrate-based valine-derived formamide organocatalyst had high catalytic activity for the asymmetric reduction of imines with trichlorosilane. The reduction can proceed at room
Chiral N-heterocyclic carbene-iridium complexes for asymmetric reduction of prochiral ketimines
作者:Lakshay Kathuria、Ashoka G. Samuelson
DOI:10.1016/j.poly.2020.114976
日期:2021.2
phenylglycine derived chiral NHC was shown to give the best Ir catalyst and it also gave the maximum ee compared to catalysts prepared from other NHCs in this series. The opposite enantiomer of the reduction product was always obtained while using the Ir complex bearing a valine based NHC. The yields were consistently high with a variety of imine substrates having different steric and electronic demands
Chiral phosphine-phosphoramidite ligands for highly enantioselective hydrogenation of N-arylimines
作者:Qing Li、Chuan-Jin Hou、Xiao-Ning Liu、De-Zhi Huang、Yan-Jun Liu、Rui-Feng Yang、Xiang-Ping Hu
DOI:10.1039/c4ra16062b
日期:——
The asymmetrichydrogenation of N-arylimines with the chiral phosphine-phosphoramidite ligand, (Sc,Sa)-PEAPhos 2b, has been developed. The results revealed that the presence of the substituents on the 3,3′-positions of the binaphthyl backbone significantly improved the enantioselectivity. The utility of this methodology was demonstrated in the synthesis of the chiral fungicide (R)-metalaxyl.
Internal Adduct Formation of Active Intramolecular C<sub>4</sub>-bridged Frustrated Phosphane/Borane Lewis Pairs
作者:Xiaowu Wang、Gerald Kehr、Constantin G. Daniliuc、Gerhard Erker
DOI:10.1021/ja413060u
日期:2014.2.26
The tetramethylene-bridged PMes2/B(C6F5)2 frustratedLewispair (FLP) 8 was prepared by hydroboration of Mes2P-(CH2)2CH═CH2 with HB(C6F5)2. It is an active FLP that splits dihydrogen under mild conditions and, consequently, serves as a metal-free hydrogenation catalyst for a variety of substrates. It also reacts typically with terminal acetylenes. The C4-bridged FLP 23 was prepared by HB(C6F5)2 hydroboration
Asymmetric reduction of imines with trichlorosilane catalyzed by valine-derived formamide immobilized onto magnetic nano-Fe<sub>3</sub>O<sub>4</sub>
作者:Xin Ge、Chao Qian、Xiaoming Ye、Xinzhi Chen
DOI:10.1039/c5ra08516k
日期:——
were synthesized by anchoring valine-derived formamide onto the surface of Fe3O4 magnetic nanoparticles, which were applied in the asymmetricreduction of imines with trichlorosilane at room temperature in toluene. The high level of yield and enantioselectivity catalyzed by magnetic nano-Fe3O4-supported organocatalysts was obtained. In the immobilization process, CuI-catalyzed azide-alkyne 1,3-dipolar
通过将缬氨酸衍生的甲酰胺固定在Fe 3 O 4磁性纳米颗粒的表面上,合成了磁性纳米Fe 3 O 4负载的有机催化剂,并将其应用于室温下用三氯硅烷在甲苯中不对称还原亚胺。获得了磁性纳米Fe 3 O 4负载的有机催化剂催化的高产率和对映选择性。在固定过程中,Cu I催化的叠氮化物-炔烃1,3-偶极环加成(CuAAC)“点击化学”用作锚定桥。磁性纳米颗粒可以简化有机催化剂的回收及其从反应体系中的分离。通过外部磁体,催化剂可以循环使用五次,而活性没有明显下降。