title: Bromoporphyrins as versatile synthons for modular construction of chiral porphyrins: cobalt-catalyzed highly enantioselective and diastereoselective cyclopropanation.
abstract: 5,10-Bis(2',6'-dibromophenyl)porphyrins bearing various substituents at the 10 and 20 positions were demonstrated to be versatile synthons for modular construction of chiral porphyrins via palladium-catalyzed amidation reactions with chiral amides. The quadruple carbon-nitrogen bond formation reactions were accomplished in high yields with different chiral amide building blocks under mild conditions, forming a family of D2-symmetric chiral porphyrins. Cobalt(II) complexes of these chiral porphyrins were prepared in high yields and shown to be active catalysts for highly enantioselective and diastereoselective cyclopropanation under a practical one-pot protocol (alkenes as limiting reagents and no slow addition of diazo reagents).
authors.affiliation: Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
authors.forename: Kimberly B
authors.initials: KB
authors.lastname: Fields
authors.forename: X Peter
authors.initials: XP
authors.lastname: Zhang