نتایج جستجو برای: asymmetric catalysis
تعداد نتایج: 90956 فیلتر نتایج به سال:
Asymmetric enamine base activation of carbonyl compounds is a well-known and widely used strategy for providing functionalization organic in an efficient way. The use solely substances, which most cases are commercially available primary or secondary amines that easy to obtain, avoids the hazardous substances metal traces, making this type catalysis highly convenient methodology from sustainabl...
Large asymmetric amplification originating from solubility differences between the enantiopure and the racemic catalyst is observed in the addition of Grignard reagents to enones. This behaviour is not reaction or catalyst specific and is observed for metal complexes of a variety of chiral diphosphine ligands, extensively used in asymmetric catalysis.
The cyclic peptide gramicidin S was used as a rigid template to provide novel peptide-based bisphosphine ligands for transition metal catalysis. Two bisphosphine-coordinated Rh(I) complexes allowed asymmetric hydrogenation with 10-52% ee and the corresponding Pd(II) analogues catalysed asymmetric allylic alkylation with 13-15% ee.
The dual activation of simple substrates by the combination of organocatalysis and palladium catalysis has been successfully applied in a variety of different asymmetric transformations. Thus, the asymmetric a-allylation of carbonyl compounds, a-fluorination of acyl derivatives, decarboxylative protonation of β-dicarbonyl compounds, cyclization reactions of alkynyl carbonyl compounds and β-func...
A novel way to accommodate heterogeneous catalysis, CO2 fixation and asymmetric synthesis on one catalyst is reported. The [Co]@Ag composite was prepared for the first time and used for asymmetric carboxylation of benzyl bromides with CO2. All the procedures were performed under mild conditions. Moreover, the [Co]@Ag composite has terrific stability and reusability.
The construction of chiral biaryl alcohols using enantio-relay catalysis is a particularly attractive synthetic method in organic synthesis. However, overcoming the intrinsic incompatibility of distinct organometallic complexes and the reaction conditions used are significant challenges in asymmetric catalysis. To overcome these barriers, we have taken advantage of an enantio-relay catalysis st...
Since their discovery, cyclodextrins have widely been used as green and easily available alternatives to promoters or catalysts of different chemical reactions in water. This review covers the research and application of cyclodextrins and their derivatives in asymmetric and stereospecific syntheses, with their division into three main groups: (1) cyclodextrins promoting asymmetric and stereospe...
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