Enantioselective Cyclopropanation of Styrene Catalysed by Copper(I) Complexes with Chiral Oxazolines

A large set of copper complexes, prepared in situ from copper(I)-triflate and a variety enantiopure oxazoline ligands, was assessed as chiral catalysts in the enantioselective cyclopropanation of styrene by ethyl diazoacetate. Enantioselectivities up to 60% and up to 52%, respectively, for trans- and cis-2-phenylcyclopropanecarboxylate were observed.