Bioinspired Manganese and Iron Complexes with Tetradentate N Ligands for the Asymmetric Epoxidation of Olefins.

The manganese and iron complexes with the tetradentate N ligand (1 R,2 R)- N, N'-dimethyl- N, N'-bis(1-methyl-2-benzimidazolylmethyl)cyclohexane-1,2-diamine have been synthesized and characterized. The crystal structure of the manganese complex demonstrates a cis-α configuration. Both the manganese and iron complexes are active catalysts for the asymmetric epoxidation of olefins with H₂O₂ as an oxidant and acetic acid as an additive. Up to 96 % ee was observed for the epoxidation of α,β-unsaturated ketones at −20 °C. [ABSTRACT FROM AUTHOR]