Asymmetric Epoxidation of Olefins with Sodium Percarbonate Catalyzed by <i>Bis</i>-amino-<i>bis</i>-pyridine Manganese Complexes

Abstract

Asymmetric epoxidation of a series of olefinic substrates with sodium percarbonate oxidant in the presence of homogeneous catalysts based on Mn complexes with bis-amino-bis-pyridine ligands is reported. Sodium percarbonate is a readily available and environmentally benign oxidant that is studied in these reactions for the first time. The epoxidation proceeded with good to high yields (up to 100%) and high enantioselectivities (up to 99% ee) using as low as 0.2 mol. % catalyst loadings. The epoxidation protocol is suitable for various types of substrates, including unfunctionalized alkenes, α,β-unsaturated ketones, esters (cis- and trans-), and amides (cis- and trans-). The reaction mechanism is discussed.

Keywords

• enantioselective
• epoxidation
• manganese
• sodium percarbonate
• olefin
• alkene