Campus Units
Chemistry
Document Type
Article
Publication Version
Published Version
Publication Date
4-2012
Journal or Book Title
Organometallics
Volume
31
Issue
9
First Page
3628
Last Page
3635
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.
Copyright Owner
American Chemical Society
Copyright Date
2012
Language
en
File Format
application/pdf
Recommended Citation
Anding, Bernie; Ellern, Arkady; and Woo, L. Keith, "Olefin Cyclopropanation Catalyzed by Iridium(III) Porphyrin Complexes" (2012). Chemistry Publications. 777.
https://lib.dr.iastate.edu/chem_pubs/777
Comments
Reprinted (adapted) with permission from Organometallics 31 (2012): 3628, doi:10.1021/om300135f. Copyright 2012 American Chemical Society.