Bioinspired iron-catalyzed olefin oxidations: Epoxidation vs. cis-dihydroxylation

PETR 9

Lawrence Que Jr., que@chem.umn.edu, Paul D. Oldenburg, oldenburg@chem.umn.edu, and Ruben Mas-Balleste, mas@chem.umn.edu. Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St SE, Minneapolis, MN 55455
We have been investigating the iron-catalyzed oxidations of olefins by H2O2 as inspired by the oxidation chemistry of nonheme iron enzymes. Highly stereoselective conversions of olefins to epoxides and/or cis-diols have been observed with the use of Fe(N4)(OTf)2 and Fe(N2Ox)(OTf)y complexes where N4 is a tetradentate ligand with four nitrogen donor sites and N2Ox is a polydentate ligand with two pyridines and one or two oxygen atom donors. The nature of the oxidizing species is a question of great interest, and possible oxidants include FeIII-OOH, FeIV=O and FeV=O species. Insights into the catalytic mechanisms of these complexes have been obtained from a combination of product distribution studies with different olefin substrates, 18O labeling experiments, and spectroscopic characterization of intermediates trapped at low temperature. Our current views on how these bio-inspired oxidations work will be presented.
 

Mechanism in Homogeneous and Heterogeneous Catalytic Epoxidation
8:15 AM-12:00 PM, Sunday, August 19, 2007 Boston Park Plaza -- Whittier Rm, Oral

Division of Petroleum Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007