Metalloradical activation of α-formyldiazoacetates for the catalytic asymmetric radical cyclopropanation of alkenes† †Electronic supplementary information (ESI) available. CCDC 1532256. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc00658f Click here for additional data file. Click here for additional data file.

For the first time, a-formyldiazoacetates have been successfully applied for the asymmetric cyclopropanation of alkenes via Co(II)-based metalloradical catalysis. The cobalt(II) complex of the D2symmetric chiral amidoporphyrin [Co(3,5-DiBu-ChenPhyrin)] is an effective metalloradical catalyst that can activate a-formyldiazoacetates to cyclopropanate both aromatic and aliphatic olefins with varied electronic properties, affording the synthetically useful 1,1-cyclopropaneformylesters in high yields with both high diastereoand enantioselectivity.