| Abstract
| - The cobalt(II) complex of D2-symmetric chiral porphyrin[Co(1)] is an effective catalyst for highly diastereoselectiveand enantioselective cyclopropanation of a broad range ofstyrene derivatives under mild conditions. Dimerization ofdiazo compounds, a common side reaction in metal-mediatedcarbene transfer processes, is minimized in a cobalt porphyrin-based system, obviating the need to employ excesssubstrates and slow addition of diazo compounds. The highcatalytic activity and selectivity of [Co(1)] evidently resultedfrom the appropriate combination of the cobalt ion and thechiral porphyrin 1 as the use of iron(III) complex of the sameligand [Fe(1)Cl] afforded the desired cyclopropane productsin low yields and poor enantioselectivity.
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