Non-heme manganese complexes of C1-symmetric N4 ligands: Synthesis, characterization and asymmetric epoxidations of α,β-enones

A series of proline-derived C1-symmetric chiral tetradentate N ligands and their manganese complexes have been synthesized and characterized. Their applications in enantioselective epoxidations of α,β-enones were explored reaching good yields and up to 71% ee at room temperature.

Graphical abstractThe enantioselective epoxidation of α,β-enones is realized with C1-symmetric chiral manganese complexes of tetradentate N4 ligands derived from naturally occurring proline, up to 71% ee were observed at room temperature.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The proline-derived C1-symmetric N4 ligands have been synthesized and characterized. ► The manganese complexes catalyzed epoxidations of α,β-enones were examined. ► Up to 71% ee was observed at room temperature. ► The 6-methyl substituents on the pyridine rings of ligands clearly inhibited the epoxidation.