Original use of the same heterogeneous chiral catalyst batch to promote different asymmetric reactions
作者:Anaïs Zulauf、Mohamed Mellah、Emmanuelle Schulz
DOI:10.1039/b913516b
日期:——
An electrogenerated heterogeneous chiral (poly)salen-thiophene chromium complex successfully promoted different asymmetric catalytic reactions in an original successive manner, demonstrating its high stability and versatility.
New Chiral Calixsalen Chromium Complexes: Recyclable Asymmetric Catalysts
作者:Anaïs Zulauf、Mohamed Mellah、Emmanuelle Schulz
DOI:10.1002/chem.201001012
日期:——
ylenediamine (salen) polymer has been prepared by a condensation reaction between a thiophenedisalicyladehyde derivative and (S,S)‐cyclohexane‐1,2‐diamine. This polymeric compound was demonstrated to possess a cyclic structure with two to five repetitive units. The addition of chromium(II) salts led to the generation of a chiral catalyst that could be recovered as an insoluble powder. The performance
We have succeeded in developing direct syntheses of trans β-azidohydrins and trans 1,2-diol derivatives from olefins catalyzed by dichlorotin oxide. The regioselectivity of these reactions with tri-substituted olefins is high (10:1 in the synthesis of 1,2-diol derivatives) to excellent (>99:1 in the synthesis of azidohydrins). It has been found that these reactions do not proceed via epoxides.
Chiral Chromium Salen@rGO as Multipurpose and Recyclable Heterogeneous Catalyst
作者:Mariam Abd El Sater、Mohamed Mellah、Diana Dragoe、Emilie Kolodziej、Nada Jaber、Emmanuelle Schulz
DOI:10.1002/chem.202101003
日期:2021.6.25
to promote asymmetric catalysis in repeated cycles, without loss of activity or enantioselectivity. This specific behavior was demonstrated in two different catalytic reactions (up to ten reuses) promoted by chromium salen complexes, the cyclohexene oxide ring-opening reaction and the hetero-Diels-Alder cycloaddition between various aldehydes and Danishefsky's diene. Furthermore, the chiral chromium
A New Synthesis of Optically Active<i>trans</i>β-Amino Alcohols by Asymmetric Ring-opening of Symmetrical Oxiranes
作者:Hiroyuki Yamashita
DOI:10.1246/cl.1987.525
日期:1987.3.5
The asymmetric ring-opening of symmetrical oxiranes with aniline or trimethylsilyl azide is effectively catalyzed by zinc (2R,3R)-tartrate or cupric (2R,3R)-tartrate to give trans N-phenyl (β-amino alcohol or trans O-trimethylsilyl 2-azido alcohols in 17–52% ee. The latter azido products can be easily converted into optically active trans β-amino alcohols by two-step procedure.
对称环氧乙烷与苯胺或三甲基甲硅烷基叠氮化物的不对称开环在 (2R,3R)-酒石酸锌或 (2R,3R)-酒石酸铜有效催化下得到反式 N-苯基(β-氨基醇或反式 O-三甲基甲硅烷基) 2-叠氮醇的 ee 含量为 17-52%。后者的叠氮产物可以通过两步程序轻松转化为光学活性的反式 β-氨基醇。