Synthesis of Chiral Bis(dihydrooxazolylphenyl)oxalamides, a New Class of Tetradentate Ligands for Asymmetric Catalysis

Abstract

Chiral tetradentate nitrogen ligands containing two coordinating oxalamide nitrogens and two dihydrooxazole rings are readily prepared in an enantiomerically pure form. The structures of two metal complexes (1, M = Cu, Ni) were determined by X-ray analysis. Ruthenium and cobalt complexes were tested as catalysts for the epoxidation of trans-stilbene (69% ee) and for Michael reactions of malonates with chalcone (up to 89% ee).