SYNTHESIS OF CHIRAL BIS(DIHYDROOXAZOLYLPHENYL)OXALAMIDES, A NEW CLASSOF TETRADENTATE LIGANDS FOR ASYMMETRIC CATALYSIS

Enantiomerically pure N'-bis[2-(4,5-dihydrooxazol-2-yl)phenyl]oxalamid es are readily prepared from 2-(2-aminophenyl)-4,5-dihydrooxazoles and oxalyl chloride. The structures of the corresponding nickel and coppe r complexes were determined by X-ray analysis. Ruthenium complexes, pr epared in situ from RuCl3 and the corresponding ligands, catalyze the enantioselective epoxidation of trans-stilbene to afford trans-1,2-dip henyloxirane with up to 69% ee. The cobalt complexes were tested as ca talysts in Michael reactions of malonates with chalcone (up to 89% ee) .