Stereoselective intramolecular cyclopropanation of alpha-diazoacetates via Co(II)-based metalloradical catalysis

Co(II) complexes of D-2-symmetric chiral porphyrins have been proven to be effective metalloradical catalysts for the asymmetric intramolecular cyclopropanation of allyl oc-diazoacetates. 4-(Dimethylamino)pyridine (DMAP), through a positive trans effect, plays an important rote in the enhancement of the asymmetric induction for the intramolecular cyclopropanation process. This metalloradical catalytic system is suitable for cyclopropanation of ally' o-diazoacetates with varied functional groups and substitution patterns, producing bicyclic products with complete diastereocontrol and good enantiocontrol.