The two diastereomers of novel C-2-symmetric bisoxazoline ligand bearing only two ortho-substituents 4 exist in equilibrium in solution, However, when the ligand was coordinated with Cu(I), only one of the two possible diastereomeric complexes, 5-(S,S,S), was formed. With this complex as a chiral catalyst, up to 92% ee was attained for the asymmetric cyclopropanation of styrene with diazoacetate. (C) 1997 Elsevier Science Ltd.