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

摘要: Abstract Substituted mono- and bis-pinene-[5,6]-bipyridines are useful ligands in asymmetric copper-catalyzed cyclopropanation by styrenes. Copper complexes were prepared either situ or prior to the reaction. The catalytic reaction of styrene with ethyl diazoacetate Cu – 11b yields trans -phenylcyclopropane carboxylate >99% yield 87% e.e. at 0°C. corresponding cis -configured cyclopropane was produced an 90%. / ratio is 22:78. Other this series less effective. Various olefins tested as substrates but exo -methylene show best results.