A new, efficient heterogeneous Pd catalyst for enantioselective allylic substitution
METADATA ONLY
Loading...
Author / Producer
Date
2008-02-15
Publication Type
Journal Article
ETH Bibliography
yes
Citations
Altmetric
METADATA ONLY
Data
Rights / License
Abstract
The enantioselective allylic substitution of (E)-1,3-diphenylallyl acetate with dimethyl malonate was studied on Pd/Al2O3 in the presence of optically active ferrocenyl phosphines as chiral modifiers. These catalyst systems offer 81–92% yield in 2–6 h, along with good enantioselectivity (45–88% ee) despite the elevated reaction temperature (60–120 °C) and the low modifier/substrate ratio (0.2 mol%). Addition of the modifiers to Pd leads to significant rate acceleration and some modifiers induce also kinetic resolution of the racemic allylic acetate substrate. The remarkably different behavior of heterogeneous and homogeneous Pd–(R)-(S)-Josiphos catalyst systems, and particularly the missing enantioselection after removal of Pd/Al2O3, indicate that the enantioselective transformation occurs at the chirally modified Pd surface.
Permanent link
Publication status
published
External links
Editor
Book title
Journal / series
Volume
254 (1)
Pages / Article No.
79 - 83
Publisher
Elsevier
Event
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
Asymmetric allylic substitution; Josiphos ligand; Chiral ferrocenyl phosphine; Palladium/alumina; Rate acceleration
Organisational unit
03285 - Baiker, Alfons (emeritus)
03285 - Baiker, Alfons (emeritus)