Alkene epoxidation catalyzed by manganese complexes with electronically modified 1,10-phenanthroline ligands

The syntheses and alkene epoxidation activities of four manganese(II) complexes with electronically modified 1,10-phenanthroline ligands are reported. Each phenanthroline has a different substituent in the 5-position; the placement ensures that the modifications influence the reactivity through largely electronic effects. All four manganese complexes catalyze the conversion of alkenes to epoxides by commercially available peracetic acid. With each of the four alkenes investigated, the yield of the epoxide product is greater when the 5-substituent on the catalyst is strongly electron-donating, contrary to what has been observed with reactions catalyzed by manganese–salen complexes.

Graphical abstractManganese(II) complexes with electronically modified phenanthroline ligands are reported. The compounds catalyze the epoxidation of alkenes by peracetic acid. The more electron-rich phenanthrolines are associated with more active olefin epoxidation.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Manganese(II) complexes with electronically modified phenanthrolines have been prepared. ► The Mn(II) compounds catalyze the epoxidation of alkenes. ► The electronic perturbations have an effect on the activity opposite to that expected.