Probing Electronic Effects in the Asymmetric Heck Reaction with the BIPI Ligands
作者:Carl A. Busacca、Danja Grossbach、Regina C. So、Erin M. O'Brie、Earl M. Spinelli
DOI:10.1021/ol0340179
日期:2003.2.1
new BIPI ligands are phosphinoimidazolines that can be electronically tuned in three different ligand regions to explore electronic effects in asymmetric catalysis. Their application to the asymmetricHeckreaction (AHR) in the creation of a chiral quaternary center is described. Enantioselectivity is shown for the first time to depend linearly on phosphine electron density. Changing the ligand basicity
Changing the Palladium Coordination to Phosphinoimidazolines with a Remote Triazole Substituent
作者:Verónica de la Fuente、Rocío Marcos、Xacobe C. Cambeiro、Sergio Castillón、Carmen Claver、Miquel A. Pericàs
DOI:10.1002/adsc.201100684
日期:2011.12
Phosphinoimidazoline (PHIM) ligands bearing a triazolylmethyl substituent at the sp3 nitrogen atom in the imidazoline ring lead to highly improved enantioselectivity (up to 99% ee) in allylic substitution reactions with respect to analogous ligands with substituents lacking the triazole unit. NMR and theoretical studies support a shift in the coordination mode of the PHIM ligand to palladium, triggered
Recycling of allylic alkylation Pd catalysts containing phosphine-imidazoline ligands in ionic liquids
作者:Verónica de la Fuente、Nicolas Fleury-Brégeot、Sergio Castillón、Carmen Claver
DOI:10.1039/c2gc35732a
日期:——
An efficient catalytic system to perform allylic alkylation in ionic liquids based on a Pd/phosphine imidazoline system has been designed. This system affords very good results (ee's up to 95%) when used with the appropriate ionic liquid as well as under microwave conditions. Recycling experiments were conducted showing very promising results.
Zwitterionic Iridium Complexes with P,N-Ligands as Catalysts for the Asymmetric Hydrogenation of Alkenes
作者:Axel Franzke、Andreas Pfaltz
DOI:10.1002/chem.201003314
日期:2011.4.4
Several zwitterionic iridium complexes based on chiralP,N‐ligands with imidazoline or oxazoline donors and anionic tetraarylborate or aryltrifluoroborate substituents have been synthesized. The corresponding cationic analogues have also been prepared, to evaluate the effect of the covalent linkage between the anion and the cationic metal complex in catalytic reactions. The respective pairs of structurally