Synthesis of chiral bis(oxazolinyl)biferrocene ligands and their application to Cu(I)-catalyzed asymmetric cyclopropanation

Article abstract of DOI:10.1016/S0957-4166(97)00097-9

Homochiral bis(oxazolinyl)biferrocene ligands, which have both planar and central chirality, are synthesized from oxazolinylferrocenes through a diastereoselective directed lithiation followed by an oxidative dimerization. Asymmetric cyclpropanation of styrene with diazoacetates in the presence of 5 mol% CuOTf-bis(oxazolinyl)biferrocene complexes gives 2-(phenyl)cyclopropane carboxylates in up to 99% ee.