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Ligand Effect on Cobalt(II)-Catalyzed Asymmetric Cyclopropanation with Diazosulfones – Approaching High Stereoselectivity through Modular Design of D2-Symmetric Chiral Porphyrins



A significant ligand effect study has been summarized for asymmetric cyclopropanation with diazosulfones catalyzed by CoII complexes of a series of D2-symmetric chiral porphyrins. The structure of the ligands was shown to play an important role in both the reactivity and the stereoselectivity of the reactions. Fine-tuning of the porphyrin ligand environments led to the development of an efficient CoII-based catalytic system for cyclopropanation of styrene with diazosulfones in high diastereoselectivity and enantioselectivity.