Synthesis of Chiral <i>N</i>-Heterocyclic Carbene Ligands with Rigid Backbones and Application to the Palladium-Catalyzed Enantioselective Intramolecular α-Arylation of Amides
Chiral N-heterocyclic carbene (NHC) ligands having a 2,2′-bisquinoline-based C2 symmetric skeleton were developed. The ligands exhibited good enantioselectivity in palladium-catalyzedintramolecularα-arylation of amides to give 3,3-disubsituted oxindoles.
Matching the Chirality of Monodentate N-Heterocyclic Carbene Ligands: A Case Study on Well-Defined Palladium Complexes for the Asymmetric α-Arylation of Amides
N-Heterocyclic carbeneligands derived from C(2)-symmetric diamines with naphthyl side chains are introduced as chiral monodentate ligands, and their palladium complexes (NHC)Pd(cin)Cl are prepared. These compounds exist as a mixture of diastereomers, and the palladium complexes can be successfully separated and their absolute stereochemistry assigned. When used in the asymmetricintramolecular alpha-arylation
Bulky Chiral Carbene Ligands and Their Application in the Palladium-Catalyzed Asymmetric Intramolecular α-Arylation of Amides
作者:E. Peter Kündig、Thomas M. Seidel、Yi-xia Jia、Gérald Bernardinelli
DOI:10.1002/anie.200703408
日期:2007.11.12
New Chiral N-Heterocyclic Carbene Ligands in Palladium-Catalyzed α-Arylations of Amides: Conformational Locking through Allylic Strain as a Device for Stereocontrol
作者:Yi-Xia Jia、Dmitry Katayev、Gérald Bernardinelli、Thomas M. Seidel、E. Peter Kündig
DOI:10.1002/chem.201000031
日期:——
Enders/Herrmann‐type chiral N‐heterocyclic carbene (NHC) ligands have been developed and applied in asymmetric palladium‐catalyzed intramolecular α‐arylations of amides. The best ligands feature the bulky tert‐butyl group and ortho‐substituted aryl groups at the stereogenic centers. Aryl bromides readily react at room temperature and aryl chlorides at 50 °C. The highly enantiomerically enriched (up