Improved Catalysts for the Palladium-Catalyzed Synthesis of Oxindoles by Amide α-Arylation. Rate Acceleration, Use of Aryl Chloride Substrates, and a New Carbene Ligand for Asymmetric Transformations
作者:Sunwoo Lee、John F. Hartwig
DOI:10.1021/jo005761z
日期:2001.5.1
alpha-aryloxindole derivatives. Surprisingly, catalysts containing tert-butylphosphine ligands, which have been most reactive for ketone arylations, were less active than those containing PCy(3). Use of new, optically active heterocyclic carbene ligands gave substantial enantioselectivity in formation of an alpha,alpha-disubstituted oxindole. In contrast, a variety of optically active phosphine ligands
Six-Membered, Chiral NHCs Derived from Camphor: Structure–Reactivity Relationship in Asymmetric Oxindole Synthesis
作者:Markus J. Spallek、Dominic Riedel、Frank Rominger、A. Stephen K. Hashmi、Oliver Trapp
DOI:10.1021/om201166b
日期:2012.2.13
A series of three chiral, expanded six-membered NHC–palladium(II) complexes was prepared with successively increased sterical demand, while retaining natural d-(+)-camphor as a chiral motif. The catalysts showed different reaction profiles in the asymmetric, intramolecularα-arylation of amides. The molecular structure of two N-heterocyclic and one nitrogen acyclic carbene palladium isonitrile complex