Enantioselective catalytic cyclopropanation of styrenes by copper complexes with chiral pinene-[5,6]-bipyridine ligands

Autor:	Helen Stoeckli-Evans, Stefan Rupprecht, Alex von Zelewsky, Didier Lötscher
Rok vydání:	2000
Předmět:	Chemistry Cyclopropanation Organic Chemistry Enantioselective synthesis Medicinal chemistry Catalysis Cyclopropane Inorganic Chemistry chemistry.chemical_compound Bipyridine Ethyl diazoacetate Organic chemistry Carboxylate Physical and Theoretical Chemistry Methylene
Zdroj:	Tetrahedron: Asymmetry. 11:4341-4357
ISSN:	0957-4166
DOI:	10.1016/s0957-4166(00)00401-8
Popis:	Substituted mono- and bis-pinene-[5,6]-bipyridines are useful ligands in asymmetric copper-catalyzed cyclopropanation by styrenes. Copper complexes were prepared either in situ or prior to the reaction. The catalytic reaction of styrene with ethyl diazoacetate and Cu – 11b yields ethyl trans -phenylcyclopropane carboxylate in >99% yield and 87% e.e. at 0°C. The corresponding cis -configured cyclopropane was produced with an e.e. of 90%. The cis / trans ratio is 22:78. Other ligands of this series are less effective. Various olefins were tested as substrates but exo -methylene olefins show the best results.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::4cc04f73f68a337e614e3a25c449471b https://doi.org/10.1016/s0957-4166(00)00401-8 Zobrazit plný text záznamu Full Text from ScienceDirect