Chiral Bis(oxazolinyl)phenyl RuIICatalysts for Highly Enantioselective Cyclopropanation

Good to excellent enantioselectivities(up to 99 % ee) of trans‐cyclopropane derivatives were achieved in the cyclopropanation of alkenes with tert‐butyl α‐diazoacetate by using 0.5 mol % of a mononuclear chiral ruthenium aqua complex containing the chiral bis(oxazolinyl)phenyl ligand, which was obtained via CH activation by RuCl3⋅3 H2O in the presence of Mg and cyclooctadiene (cod). Intramolecular cyclopropanation reactions using the new Ru complex also proceed with high yields and excellent enantioselectivities.