Chiral N,N‘- and N,O-Bidentate Anionic Ligands. Preparation, Metal Complexation, and Evaluation in the Asymmetric Aziridination of Olefins

The chiral ligands 1-phenyl-2-[(4 S )-phenyl-4,5-dihydrooxazol-2-yl]propen-2-ol ( 1a ) and [1-phenyl-2-((4 S )-phenyl-4,5-dihydrooxazol-2-yl)vinyl]- p -tolylamine ( 2a ) were prepared, together with some structural analogues ( 1b − e, 2b ) in two steps from optically pure phenylglycinol or phenylalaninol. Transition-metal−ligand complexes were isolated from the ligand 1a and Cu(II), Pd(II), and Co(II). The copper complexes of 1a and 2a were found to be highly active catalysts for the asymmetric aziridination of styrene, giving the corresponding N -tosylaziridine in excellent yields and with enantiomeric excess in the range of 15−34%.