نتایج جستجو برای: asymmetric catalysis
تعداد نتایج: 90956 فیلتر نتایج به سال:
Chiral phase-transfer catalysis is one of the major catalytic principles in asymmetric catalysis. A broad variety of different catalysts and their use for challenging applications have been reported over the last decades. Besides asymmetric C-C bond forming reactions the use of chiral phase-transfer catalysts for enantioselective α-heterofunctionalization reactions of prochiral nucleophiles bec...
To combine the high chemical performance of asymmetric catalysis with the increasing need for sustainability, a strategy is presented that involves the straightforward preparation of "Trost"-like ligands suitable for application in multiphasic homogeneous catalysis. Ligands with coordinating functions (phosphinoamide-phoshinoester groups) as well as phase tags introduced on a D-glucose scaffold...
One possible way to take advantage of such abilities may be to apply a ‘combined acids system’ [2] to the catalyst design. The concept of combined acids, which can be classified into Brønsted acid-assisted Lewis acid (BLA), Lewis acid-assisted Lewis acid (LLA), Lewis acid-assisted Brønsted acid (LBA), and Brønsted acid-assisted Brønsted acid (BBA), can be a particularly useful tool for the desi...
An enantioselective dearomatization of isoquinolines has been developed using chiral anion-binding catalysis. This transformation, catalyzed by a simple and easy to prepare tert-leucine-based thiourea derivative, makes use of silyl phosphite as a nucleophile and generates cyclic α-aminophosphonates. This is the first time asymmetric anion-binding catalysis has been applied to the synthesis of α...
The research in the field of asymmetric carbene organic catalysis has primarily focused on the activation of carbon atoms in non-aromatic scaffolds. Here we report a reaction mode of carbene catalysis that allows for aromatic aldehyde activation and remote oxygen atom functionalization. The addition of a carbene catalyst to the aldehyde moiety of 2-hydroxyl aryl aldehyde eventually enables dear...
In the last years huge efforts have been made to develop new activation modes in order to synthesize complex scaffolds in an enantiopure form. The most common approach has been the development of new catalysts to activate an “unreactive” compound A that will react with a highly reactive compound B to render C. However, recently a new approach pushes the boundaries of organic chemistry: synergis...
Anion–p interactions have been introduced recently to catalysis. The idea of stabilizing anionic intermediates and transition states on p-acidic surfaces is a new fundamental concept. By now, examples exist for asymmetric enolate, enamine, iminium and transamination chemistry, and the first anion–p enzyme has been created. Delocalized over large aromatic planes, anion–p interactions appear part...
Anion-π interactions have been introduced recently to catalysis. The idea of stabilizing anionic intermediates and transition states on π-acidic surfaces is a new fundamental concept. By now, examples exist for asymmetric enolate, enamine, iminium and transamination chemistry, and the first anion-π enzyme has been created. Delocalized over large aromatic planes, anion-π interactions appear part...
The common use of NHC complexes in transition-metal mediated C–C coupling and metathesis reactions in recent decades has established N-heterocyclic carbenes as a new class of ligand for catalysis. The field of asymmetric catalysis with complexes bearing NHC-containing chiral ligands is dominated by mixed carbene/oxazoline or carbene/phosphane chelating ligands. In contrast, applications of comp...
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