Journal of Molecular Catalysis A-Chemical, Vol.196, No.1-2, 109-115, 2003
New chiral dinitrogen ligands containing sp(2)N-sp(3)N in the enantioselective cyclopropanation of olefins
The dihydrodinaphthazepinyl-oxazoline ligands 3 have been synthesized and tested in the copper-catalyzed enantioselective cyclopropanation. of olefins with diazoacetates. The ligands 3 were efficient in the cyclopropanations of styrene derivatives with up to 90% ee. The match of chiralities of binaphthyl and oxazoline in the ligands 3 is crucial for obtaining high enantioselectivity. The absolute configurations of cyclopropanation products were controlled mainly by the configuration of binaphthyl. (C) 2002 Elsevier Science B.V. All rights reserved.