Lunedì 28 ottobre alle ore 15.00 presso l’Aula H
Dipartimento di Scienze Chimiche, via Marzolo, 1
il Prof. John T. Groves
Department of Chemistry, Princeton University,
Princeton, NJ USA
terrà il seminario:
Metalloporphyrins in
Chemical and Biological Catalysis
In this lecture I will discuss recent developments from our lab in the areas of synthetic, biomimetic metalloporphyrin
catalysts and those of novel, heme-thiolate APO biocatalysts with an active site similar to that of cytochrome P450.
These extracellular enzymes are capable of catalyzing the monooxygenation of a variety of substrates using H2O2 as a
terminal oxidant. We have found that APO enzymes efficiently catalyze the H 2O2-dependent hydroxylation of simple
alkanes, even ethane. Drug molecules are efficiently converted in to P450-like metabolites. The benzylic hydroxylation
of ethyl benzoic acid proceeds with 100% conversion and 95% ee. The hydroxylation of cyclohexane mediated by APO
with H218O2 resulted in complete incorporation of the oxygen label into the hydroxyl group of the product cyclohexanol.
Hydroxylation of the radical clock norcarane led to a product mixture indicative of a radical rebound hydroxylation
scenario with an estimated radical lifetime of ~10 ps. We have directly observed and kinetically characterized the
reactive intermediate, « compound I », responsible for C-H hydroxylation.1,2 The mechanism of C-H hydroxylation by
APO will be compared and contrasted to those of model porphyrin systems, including a selective and efficient C-H
fluorination mediated by a model manganese porphyrin that we have recently described. 3-6
R-H
R-OH
R-H
R-F
O
N
N
IV
Fe N
N
S
O
N
V
N
N Mn N
F
Cys
1.
2.
3.
4.
5.
6.
Xiaoshi Wang, Sebastian Peter, Matthias Kinne, Martin Hofrichter, John T. Groves, Detection and Kinetic Characterization of a Highly
Reactive Heme–Thiolate Peroxygenase Compound I J. Am. Chem. Soc., 2012, 134, 12897–12900.
Xiaoshi Wang, Sebastian Peter, René Ullrich, Martin Hofrichter, and John T. Groves, Driving Force for Oxygen-Atom Transfer by HemeThiolate Enzymes, Angew. Chem. Int. Ed. 2013, 52, 9238-9241.
Wei Liu, Xiongyi Huang, Mu-Jeng Cheng, Robert J. Nielsen, William A. Goddard, III, John T. Groves, Oxidative Aliphatic C-H
Fluorination with Fluoride Ion Catalyzed by a Manganese Porphyrin, Science, 2012, 337, 1322-1325.
Wei Liu and John T. Groves Mn-Catalyzed Oxidative Benzylic C-H Fluorination Using Fluoride Ion, Angew. Chem. Int. Ed. 2013, 52,
6024-6027.
Dong Wang and John T. Groves, Efficient water oxidation catalyzed by homogeneous cationic cobalt porphyrins with critical roles for the
buffer base, Proc. Nat. Acad. Sci. U.S.A., 2013, (39) 15579-15584.
Wei Liu, Xiongyi Huang and John T. Groves, Oxidative aliphatic C-H fluorination with manganese catalysts and fluoride ion, Nature
Protocols, 2013, 8, in press.
La presenza della S. V. sarà molto gradita
Il Direttore del Dipartimento
Prof. Paolo Scrimin
ITM-CNR Sezione di Padova
Prof. Marcella Bonchio