Advanced

Entropy-Controlled and Enantiodivergent Lewis Acid Catalysis in Water

Aplander, Karolina LU ; Lindstrom, U. Marcus and Wennerberg, Johan (2012) In Synthesis 44(6). p.848-856
Abstract
Developing new and useful methods in asymmetric catalysis is of continuous importance. A current challenge is to address the imperatives of green chemistry, such that processes maximize resource-efficiency and minimize the generation of waste. To this end, this article discloses the potential of alpha-amino acids in the development of entropy-controlled and enantiodivergent Lewis acid catalysis. In an ytterbium-catalyzed aqueous Michael addition reaction, natural alpha-amino acids induced not only a large rate acceleration, but also an unusual and remarkable reversed temperature effect on enantioselectivity. As demonstrated with 17 alpha-amino acids, the enantioselectivity of the reaction can be significantly altered, and even reversed,... (More)
Developing new and useful methods in asymmetric catalysis is of continuous importance. A current challenge is to address the imperatives of green chemistry, such that processes maximize resource-efficiency and minimize the generation of waste. To this end, this article discloses the potential of alpha-amino acids in the development of entropy-controlled and enantiodivergent Lewis acid catalysis. In an ytterbium-catalyzed aqueous Michael addition reaction, natural alpha-amino acids induced not only a large rate acceleration, but also an unusual and remarkable reversed temperature effect on enantioselectivity. As demonstrated with 17 alpha-amino acids, the enantioselectivity of the reaction can be significantly altered, and even reversed, simply by modifying the reaction temperature. After determining differential thermodynamic activation parameters, it was revealed that an unusually large entropy contribution was responsible for the observed effects. By further correlation to the influence of the aqueous medium, we put forward the concept of stereospecific aqueous solvation (SAS), which describes the bearing of aqueous solvation on the equilibrium of diastereomeric transition states, and thus on the R/S ratio of the product. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
water, Michael reaction, Lewis acid, enantioselective, catalysis
in
Synthesis
volume
44
issue
6
pages
848 - 856
publisher
Oxford Polytechnic, Oxford
external identifiers
  • wos:000301344200002
  • scopus:84858080916
ISSN
0039-7881
DOI
10.1055/s-0031-1289725
language
English
LU publication?
yes
id
7a40a94b-fc1d-4916-b7be-2f497ddefd2c (old id 2510261)
date added to LUP
2012-05-15 15:34:08
date last changed
2017-01-01 06:09:00
@article{7a40a94b-fc1d-4916-b7be-2f497ddefd2c,
  abstract     = {Developing new and useful methods in asymmetric catalysis is of continuous importance. A current challenge is to address the imperatives of green chemistry, such that processes maximize resource-efficiency and minimize the generation of waste. To this end, this article discloses the potential of alpha-amino acids in the development of entropy-controlled and enantiodivergent Lewis acid catalysis. In an ytterbium-catalyzed aqueous Michael addition reaction, natural alpha-amino acids induced not only a large rate acceleration, but also an unusual and remarkable reversed temperature effect on enantioselectivity. As demonstrated with 17 alpha-amino acids, the enantioselectivity of the reaction can be significantly altered, and even reversed, simply by modifying the reaction temperature. After determining differential thermodynamic activation parameters, it was revealed that an unusually large entropy contribution was responsible for the observed effects. By further correlation to the influence of the aqueous medium, we put forward the concept of stereospecific aqueous solvation (SAS), which describes the bearing of aqueous solvation on the equilibrium of diastereomeric transition states, and thus on the R/S ratio of the product.},
  author       = {Aplander, Karolina and Lindstrom, U. Marcus and Wennerberg, Johan},
  issn         = {0039-7881},
  keyword      = {water,Michael reaction,Lewis acid,enantioselective,catalysis},
  language     = {eng},
  number       = {6},
  pages        = {848--856},
  publisher    = {Oxford Polytechnic, Oxford},
  series       = {Synthesis},
  title        = {Entropy-Controlled and Enantiodivergent Lewis Acid Catalysis in Water},
  url          = {http://dx.doi.org/10.1055/s-0031-1289725},
  volume       = {44},
  year         = {2012},
}