TY - CHAP
T1 - Bio-Inspired Iron-Catalyzed Olefin Oxidations
T2 - Epoxidation Versus Cis-Dihydroxylation
AU - Oldenburg, Paul D.
AU - Mas-Ballesté, Rubén
AU - Que, Lawrence
N1 - Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2008
Y1 - 2008
N2 - A number of nonheme iron complexes have recently been identified that catalyze the epoxidation and cis-dihydroxylation of olefins with H2O2 as oxidant. These catalysts have been inspired by a class of arene cis-dihydroxylating enzymes called the Rieske dioxygenases, the active sites of which consist of an iron center ligated by two histidines and a bidentate aspartate residue. The two remaining sites are cis to each other and are utilized for oxygen activation. The most effective biomimetic catalysts thus far have polydentate ligands that provide two such cis-oriented labile sites to activate the H2O2 oxidant. This chapter summarizes recent developments in this area of bio-inspired oxidation catalysis and discusses the evolution of the mechanistic pathways proposed to rationalize the new experimental results and the dichotomy between olefin epoxidation versus cis-dihydroxylation. The epoxidation and cis-dihydroxylation of olefins are important chemical transformations in both natural product and drug synthesis. While epoxidation typically involves either peracids or metal-based catalysts with H2O2, olefin cis-dihydroxylation involves the use of OsO4. These nonheme iron catalysts therefore potentially offer an environmentally more benign alternative to peracid-mediated epoxidations and osmium-catalyzed cis-dihydroxylation reactions. The most extensively studied ones thus far are complexes composed of tetradentate N4 ligands that have cis-oriented available coordination sites, analogous to those observed for the Rieske dioxygenase enzymes. These complexes have been shown to catalyze both the epoxidation and cis-dihydroxylation of olefins, but many factors affect which of these products is favored, revealing a surprisingly complex reaction landscape for catalysis.
AB - A number of nonheme iron complexes have recently been identified that catalyze the epoxidation and cis-dihydroxylation of olefins with H2O2 as oxidant. These catalysts have been inspired by a class of arene cis-dihydroxylating enzymes called the Rieske dioxygenases, the active sites of which consist of an iron center ligated by two histidines and a bidentate aspartate residue. The two remaining sites are cis to each other and are utilized for oxygen activation. The most effective biomimetic catalysts thus far have polydentate ligands that provide two such cis-oriented labile sites to activate the H2O2 oxidant. This chapter summarizes recent developments in this area of bio-inspired oxidation catalysis and discusses the evolution of the mechanistic pathways proposed to rationalize the new experimental results and the dichotomy between olefin epoxidation versus cis-dihydroxylation. The epoxidation and cis-dihydroxylation of olefins are important chemical transformations in both natural product and drug synthesis. While epoxidation typically involves either peracids or metal-based catalysts with H2O2, olefin cis-dihydroxylation involves the use of OsO4. These nonheme iron catalysts therefore potentially offer an environmentally more benign alternative to peracid-mediated epoxidations and osmium-catalyzed cis-dihydroxylation reactions. The most extensively studied ones thus far are complexes composed of tetradentate N4 ligands that have cis-oriented available coordination sites, analogous to those observed for the Rieske dioxygenase enzymes. These complexes have been shown to catalyze both the epoxidation and cis-dihydroxylation of olefins, but many factors affect which of these products is favored, revealing a surprisingly complex reaction landscape for catalysis.
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U2 - 10.1016/B978-0-444-53188-9.00018-3
DO - 10.1016/B978-0-444-53188-9.00018-3
M3 - Chapter
AN - SCOPUS:84887507813
SN - 9780444531889
SP - 451
EP - 469
BT - Mechanisms in Homogeneous and Heterogeneous Epoxidation Catalysis
PB - Elsevier
ER -