The Jacobsen Epoxidation allows the enantioselective formation of epoxides from various cis-substituted olefins by using a chiral Mn-salen catalyst and a stoichiometric oxidant such as bleach. Compared to the Sharpless Epoxidation, the Jacobsen Epoxidation allows a broader substrate scope for the transformation: good substrates are conjugated cis-olefins (R: Ar, alkenyl, alkynyl; R': Me, alkyl) or alkyl-substituted cis-olefins bearing one bulky alkyl group.