Biomedical Engineering Reference
In-Depth Information
6
ENANTIOSELECTIVE
ORGANOCATALYSIS:
A POWERFUL TOOL
FOR THE SYNTHESIS OF
BIOACTIVE MOLECULES
CHAPTER
MITSURU SHOJI and YUJIRO HAYASHI
Department of Industrial Chemistry, Tokyo University of Science, Tokyo, Japan
6.1.
INTRODUCTION
In the early 1970s, Hajos et al. reported the first example of an intramolecular aldol
reaction catalyzed by
L
-proline (
) (Scheme 6.1) [1]. The intermolecular version was
discovered by List et al. in 2000 (Scheme 6.2) [2]. The same year, MacMillan and
coworkers reported the asymmetric Diels-Alder reaction catalyzed by a chiral
imidazolidinone
2
(Scheme 6.3) [3]. After these two seminal articles, small chiral
organic molecules have been widely employed in asymmetric synthesis because they
have several advantages over conventional transition metal-based catalysts. Indeed,
organic catalysts are inexpensive, readily available, and nontoxic. They are also not
sensitive to moisture or oxygen, and the products formed are free from any metal
contamination. Because of all of these advantages, this field has been expanding
rapidly [4]. We describe here the recent progress made with a special emphasis given
to the applications in the synthesis of bioactive molecules.
10
O
O
O
Me
Me
CO
2
H
Me
H
H
+
2
O
MeCN
O
O
O
Me
OH
1
3
(ee = 93%)
4
SCHEME 6.1
Proline-catalyzed intramolecular aldol reaction.
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