Journal article
Enantioselective hydrogenation over cinchona-modified Pt: the special role of carboxylic acids.
Published in:
- Chemistry (Weinheim an der Bergstrasse, Germany). - 2002
English
The influence of acetic acid (AcOH) and trifluoroacetic acid (TFA) on the hydrogenation of ethyl-4,4,4-trifluoroacetoacetate has been investigated by using Pt/Al(2)O(3) modified by cinchonidine and O-methylcinchonidine. We have shown that the sometimes dramatic changes in enantioselectivity and rate cannot simply be interpreted by protonation of the alkaloid modifier. We propose a new three-step reaction pathway, involving interaction of the carboxylic acid with the reactant and the chiral modifier. The mechanism is supported by IR spectroscopic identification of cyclic TFA-modifier ion pairs. This new approach can rationalise the poorly understood role of acids in the enantioselective hydrogenation of activated ketones over cinchona-modified platinum metals.
-
Language
-
-
Open access status
-
closed
-
Identifiers
-
-
Persistent URL
-
https://sonar.ch/global/documents/127929
Statistics
Document views: 9
File downloads: