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Chiral Brønsted Acid (chiral + bronst_acid)
Selected AbstractsEnantioselective Mannich-Type Reaction Catalyzed by a Chiral Brønsted Acid Derived from TADDOLADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-13 2005Takahiko Akiyama Abstract A novel cyclic dialkyl phosphate was synthesized starting from (+)-diethyl tartrate. Its catalytic activity as a chiral Brønsted acid has been examined in the Mannich-type reaction of a ketene silyl acetal with aldimines as a model reaction. The corresponding ,-amino acid esters were obtained with high enantioselectivity. [source] Unifying Metal and Brønsted Acid Catalysis,Concepts, Mechanisms, and ClassificationsCHEMISTRY - A EUROPEAN JOURNAL, Issue 31 2010Magnus Rueping Prof. Abstract Asymmetric catalysis is a key feature of modern synthetic organic chemistry. Traditionally, different combinations of ligands and metals are used to perform highly enantioselective reactions. Since the renaissance of organocatalysis in the early 2000s, tremendous improvement in the field of metal-free catalysis has been achieved. Recently, the combination of transition metals and organocatalysts has allowed the development of new protocols enabling transformations that could not previously be realized. This article aims to present the latest contributions in the field of combined chiral Brønsted acid and metal catalyzed reactions, highlighting the advantages of these catalytic systems as well as describing the uncertainties regarding the molecular structure of the catalytically active species and the reaction mechanisms. [source] Synthesis and Application of Polymer-Supported Chiral Brønsted Acid OrganocatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010Magnus Rueping Abstract A new methodology for the immobilization of chiral Brønsted acids has been developed. The resulting heterogeneous organocatalysts have been employed in multiple consecutive catalysis cycles in the asymmetric organocatalytic transfer hydrogenation. The new catalyst system can not only be easily recovered from the reaction mixture in a tea-bag approach but it can also be easily reused in several catalytic cycles without loss of reactivity and selectivity. [source] |