title: Diastereoselective and enantioselective cyclopropanation of alkenes catalyzed by cobalt porphyrins.
abstract: Cobalt(II) porphyrin complexes were shown to be general and efficient catalysts for selective cyclopropanation of alkenes with ethyl diazoacetate (EDA). The catalytic system can operate with alkenes as limiting reagents, requiring only stoichiometric amounts of EDA. The protocol is performed in one-pot fashion without the need of slow addition of EDA. The diastereoselectivity of the current system can be tuned by using different porphyrin ligands or additives, giving either trans- or cis-dominant cyclopropanes. The asymmetric cyclopropanation was also demonstrated with the use of chiral cobalt porphyrin complexes.
authors.affiliation: Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996-1600, USA.
authors.forename: Lingyu
authors.initials: L
authors.lastname: Huang
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
authors.forename: Guang-Yao
authors.initials: GY
authors.lastname: Gao
authors.forename: X Peter
authors.initials: XP
authors.lastname: Zhang