Highly Asymmetric Intramolecular Cyclopropanation of Acceptor-Substituted Diazoacetates by Co(II)-Based Metalloradical Catalysis: Iterative Approach for Development of New-Generation Catalysts

3,5-Di^<i>t</i>Bu-QingPhyrin, a new <i>D</i>₂-symmetric chiral porphyrin derived from a chiral cyclopropanecarboxamide containing two contiguous stereocenters, has been developed using an iterative approach based on Co(II)-catalyzed asymmetric cyclopropanation of alkenes. The Co(II) complex of 3,5-Di^<i>t</i>Bu-QingPhyrin, [Co(<b>P2</b>)], has proved to be a general and effective catalyst for asymmetric intramolecular cyclopropanation of various allylic diazoacetates (especially including those with α-acceptor substituents) in high yields with excellent stereoselectivities. The [Co(<b>P2</b>)]-based intramolecular metalloradical cyclopropanation provides convenient access to densely functionalized 3-oxabicyclo[3.1.0]hexan-2-one derivatives bearing three contiguous quaternary and tertiary chiral centers with high enantiomeric purity.