Highly enantioselective cyclopropanation in alcoholic and aqueous solvents catalyzed by optically active β-ketoiminato cobalt(II) complex

The highly enantioselective cyclopropanation of styrenes and diazoacetates proceeded in alcohol or aqueous alcohol in the presence of the β-ketoiminato cobalt(II) complex. Water and alcohols accelerated the reaction and improved the diastereo- and enantioselectivities. In these media, the α,α-disubstituted styrenes were smoothly cyclopropanated with high enantiomeric excess.