Enantioselective 1,3-Dipolar Cycloaddition of Nitrones Catalyzed by Optically Active Cationic Cobalt(III) Complexes

The optically active β-ketoiminato cationic cobalt(III) complexes were employed as efficient Lewis acid catalysts for the enantioselective 1,3-dipolar cycloaddition reaction of α,β-unsaturated aldehydes with nitrones. Excellent endo selectivities and high enantioselectivities were achieved in the cycloaddition reaction of 1-cyclopentene-1-carbaldehyde and the nitrones derived from 2-halobenzaldehyde.