Highly asymmetric intramolecular cyclopropanation of acceptor-substituted diazoacetates by Co(II)-based metalloradical catalysis: iterative approach for development of new-generation catalysts

Xue Xu; Hongjian Lu; Joshua V Ruppel; Xin Cui; Silke Lopez de Mesa; Lukasz Wojtas; X Peter Zhang

doi:10.1021/ja2062506

Highly asymmetric intramolecular cyclopropanation of acceptor-substituted diazoacetates by Co(II)-based metalloradical catalysis: iterative approach for development of new-generation catalysts

J Am Chem Soc. 2011 Oct 5;133(39):15292-5. doi: 10.1021/ja2062506. Epub 2011 Sep 8.

Authors

Xue Xu¹, Hongjian Lu, Joshua V Ruppel, Xin Cui, Silke Lopez de Mesa, Lukasz Wojtas, X Peter Zhang

Affiliation

¹ Department of Chemistry, University of South Florida, Tampa, Florida 33620-5250, United States.

PMID: 21870825
DOI: 10.1021/ja2062506

Abstract

3,5-Di(t)Bu-QingPhyrin, a new D(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(t)Bu-QingPhyrin, [Co(P2)], 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(P2)]-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.