Skip to main content
Article
Olefin Cyclopropanation Catalyzed by Iridium(III) Porphyrin Complexes
Organometallics
  • Bernie Anding, Iowa State University
  • Arkady Ellern, Iowa State University
  • L. Keith Woo, Iowa State University
Document Type
Article
Disciplines
Publication Version
Published Version
Publication Date
4-1-2012
DOI
10.1021/om300135f
Abstract
Tetratolylporphyrinato (TTP) iridium complexes were shown to be extremely active and robust catalysts for the cyclopropanation of olefins using diazo compounds as carbene sources. Ir(TTP)CH3 (1) catalyzed the cyclopropanation of styrene with ethyl diazoacetate (EDA) at −78 °C and achieved 4.8 × 105 turnovers in three successive reagent additions with no sign of deactivation. High yields and moderate trans selectivities were attained for electron-rich and sterically unhindered substrates. A Hammett ρ+ value of −0.23 was determined by competition experiments with para-substituted styrenes. Furthermore, competitive cyclopropanation of styrene and styrene-d8 with EDA and 1 demonstrated a moderate inverse secondary isotope effect of 0.86 ± 0.03. These data are consistent with a catalytic cycle that proceeds through a metalloporphyrin carbene intermediate. Carbene transfer to olefin substrates appears to be rate limiting, as indicated by kinetic studies. Hexavalent iridium halogenato tetratolylporphyrinato complexes of the form Ir(TTP)X(L), where X = Cl, Br, I, NCS and L = CO, NMe3 (2–6), and cationic analogues, where X = BF4 and L = CO or vacant site (7, 8), also demonstrated high catalytic cyclopropanation activity.
Comments

Reprinted (adapted) with permission from Organometallics 31 (2012): 3628, doi:10.1021/om300135f. Copyright 2012 American Chemical Society.

Copyright Owner
American Chemical Society
Language
en
File Format
application/pdf
Citation Information
Bernie Anding, Arkady Ellern and L. Keith Woo. "Olefin Cyclopropanation Catalyzed by Iridium(III) Porphyrin Complexes" Organometallics Vol. 31 Iss. 9 (2012) p. 3628 - 3635
Available at: http://works.bepress.com/l-woo/41/