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
Remote Construction of N‐Heterocycles via 1,4‐Palladium Shift‐Mediated Double C−H Activation
作者:Takeru Miyakoshi、Nadja E. Niggli、Olivier Baudoin
DOI:10.1002/anie.202116101
日期:2022.4.19
AbstractIn the past years, Pd0‐catalyzed C(sp3)−H activation provided efficient and step‐economical methods to synthesize carbo‐ and heterocycles via direct C(sp2)−C(sp3) bond formation. We report herein that a 1,4‐Pd shift allows access to N‐heterocycles which are difficult to build via a direct reaction. It is shown thato‐bromo‐N‐methylanilines undergo a 1,4‐Pd shift at theN‐methyl group, followed by intramolecular trapping by C(sp2)−H or C(sp3)−H activation at another nitrogen substituent and remote C−C bond formation to generate biologically relevant isoindolines and β‐lactams. The product selectivity is influenced by the employed ligand, with NHCs favoring the product of remote C−C coupling against products arising from direct C−C coupling and N‐demethylation.
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