Synthesis of chiral bis(oxazolinyl)bipyridine ligands and related helical metal complexes

Enantiomerically pure tetradentate bis(oxazolinyl)bipyridine ligands 1 have been synthesized in high yields. X-Ray analysis showed that the copper(I) complexes of ligands 1 had a C-2-symmetric helical structure. Ruthenium complexes of ligands 1 prepared in situ were found to be efficient in the asymmetric cyclopropanation of styrene with ethyl diazoacetate. (C) 2002 Elsevier Science Ltd. All rights reserved.