Synthesis 2006(10): 1715-1723  
DOI: 10.1055/s-2006-926448
SPECIALTOPIC
© Georg Thieme Verlag Stuttgart · New York

α-Diazoacetates as Carbene Precursors: Metallosalen-Catalyzed Asymmetric Cyclopropanation

Tatsuya Uchida, Tsutomu Katsuki*
Department of Chemistry, Faculty of Science, Graduate School, Kyushu University, 33, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
e-Mail: katsuscc@mbox.nc.kyushu-u.ac.jp;
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Publikationsverlauf

Received 16 March 2006
Publikationsdatum:
27. April 2006 (online)

Abstract

Readily available α-diazo compounds have been shown to be efficient carbene precursors for asymmetric cyclopropanation using ruthenium(NO)-salen and cobalt-salen complexes, as catalysts. The stereoselectivity of the cyclopropanation depends on the metal ion, its valency, the structural and electronic nature of the salen ligand, and the apical ligand of the salen complex used. Both trans- and cis-selective asymmetric intermolecular cyclopropanation can be realized under mild conditions by using a suitable metallosalen complex. Furthermore, a wide range of alkenyl α-diazoacetates and the related alkenyl diazomethyl ketones undergo intramolecular cyclopropanation in a highly enantioselective manner by using various metallosalen complexes, easily prepared in a modular fashion, as catalyst.