Norbert Krause talks with
ScienceWatch.com and answers a few questions about
this month's New Hot Paper in the field of
Article Title: Golden opportunities in
Journal: ANGEW CHEM INT ED
* Dortmund Univ Technol, Otto Hahn Str 6, D-44227 Dortmund,
* Dortmund Univ Technol, D-44227 Dortmund, Germany.
Why do you think your paper is highly
The use of gold is currently at the center of interest in transition metal
catalysis. It is the unique ability of gold catalysts to selectively
activate carbon-carbon double and triple bonds in the presence of many
other functional groups which makes it highly valuable for the synthesis of
complex target molecules. Despite these advantages, applications of gold
catalysis in stereoselective synthesis are still rare. The paper highlights
the first examples for highly stereoselective gold-catalyzed
transformations, a field that is very "hot" right now.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
The widespread use of gold as a catalyst for the synthesis of fine
chemicals, natural products, and pharmaceuticals began just 10 years ago.
Hence, stereoselective transformations are also very new, compared to
other, well-established transition metals like palladium. In
stereoselective gold catalysis, both traditional methods (chirality
transfer, enantioselective synthesis) and new concepts like the use of
chiral anions show much promise.
Would you summarize the significance of your paper
in layman's terms?
"In the near future, we will focus
our research on the development of new gold
catalysts for their application in complex
chemical and biological
The review article focuses on stereoselective gold-catalyzed
transformations, i.e., reactions that allow for the selective synthesis of
one enantiomer of a chiral molecule. Enantiomers are the image and mirror
image of a molecule that cannot be superimposed. The selective synthesis of
enantiomers is particularly important for pharmaceuticals since the human
organism often interacts differently with image and mirror image. One has
the desired pharmacological activity, whereas the other is inactive, or
even harmful. A nice comparison is the human hand: a right glove does only
fit to the right hand, not to the left. A well-known example of this
difference is the drug thalidomide: one enantiomer is acting as a
tranquilizer whereas its mirror image causes birth defects.
How did you become involved in this research, and
were there any problems along the way?
We started using gold catalysts for cyclization reactions of functionalized
allenes 10 years ago and are particularly interested in the chirality
transfer from the starting material to the product. Selectivity and
reactivity are the main issues in all transition metal-catalyzed reactions.
Fortunately, both problems can be solved in gold catalysis by a
"fine-tuning" of the catalyst, using different ligands and solvents. We
have applied our cyclization reactions to the stereoselective synthesis of
various natural products and/or pharmaceutically active compounds
possessing chiral five- or six-membered heterocyclic rings.
Where do you see your research leading in the
In the near future, we will focus our research on the development of new
gold catalysts for their application in complex chemical and biological
systems. Towards this end, stability, reactivity, and selectivity have to
be improved. This requires the synthesis of new, unconventional ligands for
the gold catalyst which should also allow for its recyclability.
Do you foresee any social or political implications
for your research?
Nowadays, it is highly important to improve the sustainability of chemical
processes. In the ideal chemical reaction, all atoms of the starting
material(s) are transferred into the product(s), and no hazardous waste is
formed. In the real world, most reactions suffer from the extensive use of
energy, reagents, and/or toxic solvents (which remain as waste).
In this respect, catalytic transformations are preferable, since they use
only small amounts of catalysts which might be recyclable. Thus, performing
catalytic reactions with environmentally friendly solvents and purification
methods at room temperature is highly desirable. I am convinced that gold
catalysis will be an important tool for the development of these
Prof. Dr. Norbert Krause
Dortmund University of Technology
Dortmund, Germany Web