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
C<sub>2</sub>-symmetric N,N′-bis(terpenyl)ethylenediamines—synthesis and application in the enantioselective nitroaldol reaction
作者:Sanjay V. Malhotra、Herbert C. Brown
DOI:10.1039/c4ra00193a
日期:——
Terpene based novel chiral C2-symmetric diamines are synthesized and their utility in enantioselective C–C bond formation has been demonstrated.
基于萜烯的新型手性C2对称双胺已合成,并展示了它们在对映选择性C-C键形成中的实用性。
Enantioselective copper catalysed 1,4-conjugate addition reactions using chiral N-heterocyclic carbenes
作者:Caroline L. Winn、Frédéric Guillen、Julien Pytkowicz、Sylvain Roland、Pierre Mangeney、Alexandre Alexakis
DOI:10.1016/j.jorganchem.2005.07.024
日期:2005.12
The preparation of a variety of chiral N-heterocyclic carbene (NHC) precursors is described. The relative merits of imidazolinium salts and silver carbenes as NHC precursors are discussed with respect to their synthesis, stability and performance in the copper catalysed conjugate addition of dialkyl zinc reagents to a variety of Michael acceptors. Enantioselectivities of up to 93% were achieved using