scholarly journals Biomimetic Non-Heme Iron-Catalyzed Epoxidation of Challenging Terminal Alkenes Using Aqueous H2O2 as an Environmentally Friendly Oxidant

Molecules ◽  
2019 ◽  
Vol 24 (17) ◽  
pp. 3182
Author(s):  
Fingerhut ◽  
Vargas-Caporali ◽  
Leyva-Ramírez ◽  
Juaristi ◽  
Tsogoeva
Keyword(s):  
Active Sites ◽  
Heme Iron ◽  
Reaction Conditions ◽  
Metal Catalysis ◽  
Non Heme Iron ◽  
Heme Ligands ◽  
Terminal Olefins ◽  
Imidazole Fragment ◽  
Epoxidation Of Alkenes

Catalysis mediated by iron complexes is emerging as an eco-friendly and inexpensive option in comparison to traditional metal catalysis. The epoxidation of alkenes constitutes an attractive application of iron(III) catalysis, in which terminal olefins are challenging substrates. Herein, we describe our study on the design of biomimetic non-heme ligands for the in situ generation of iron(III) complexes and their evaluation as potential catalysts in epoxidation of terminal olefins. Since it is well-known that active sites of oxidases might involve imidazole fragment of histidine, various simple imidazole derivatives (seven compounds) were initially evaluated in order to find the best reaction conditions and to develop, subsequently, more elaborated amino acid-derived peptide-like chiral ligands (10 derivatives) for enantioselective epoxidations.

Diffuse Reflectance FT-IR Characterization of Active Sites under Reaction Conditions: The Production of Oxygenates in the CO/H2 Reaction

1994 ◽  
Vol 48 (10) ◽  
pp. 1208-1212 ◽  
Author(s):  
J. J. Benítez ◽  
I. Carrizosa ◽  
J. A. Odriozola
Keyword(s):  
Infrared Spectra ◽  
Active Sites ◽  
Diffuse Reflectance ◽  
Reaction Conditions ◽  
In Situ Drifts ◽  
Ft Ir

The reactivity of a Lu2O3-promoted Rh/Al2O3 catalyst in the CO/H2 reaction is reported. Methane, heavier hydrocarbons, methanol, and ethanol are obtained. In situ DRIFTS has been employed to record the infrared spectra under the actual reaction conditions. The structure of the observed COads DRIFTS bands has been resolved into its components. The production of oxygenates (methanol and ethanol) has been correlated with the results of the deconvolution calculation. Specific sites for the production of methanol and ethanol in the CO/H2 reaction over a Rh,Lu2O3/Al2O3 catalyst are proposed.

scholarly journals Nitrene Transfer Catalyzed by a Non-Heme Iron Enzyme and Enhanced by Non-Native Small-Molecule Cofactors

2019 ◽  
Author(s):  
Nathaniel Goldberg ◽  
Anders M. Knight ◽  
Ruijie Zhang ◽  
Frances H. Arnold
Keyword(s):  
Enzyme Activity ◽  
Small Molecules ◽  
Directed Evolution ◽  
Heme Iron ◽  
Transition Metal Catalysis ◽  
Chemical Bonds ◽  
Metal Catalysis ◽  
Nitrene Transfer ◽  
Non Heme Iron ◽  
Iron Center

Transition-metal catalysis is a powerful tool for the construction of chemical bonds. Here we show that a non-heme iron enzyme can catalyze olefin aziridination and nitrene C–H insertion, and that these activities can be improved by directed evolution. The non-heme iron center allows for facile modification of the primary coordination sphere by addition of metal-coordinating molecules, enabling control over enzyme activity and selectivity using small molecules.

Biocatalyst-Initiated Ortho-Quinone Methide Formation and Derivatization

2019 ◽  
Author(s):  
Tyler Doyon ◽  
Jonathan Perkins ◽  
Summer A. Baker Dockrey ◽  
Kevin Skinner ◽  
Paul M. Zimmerman ◽  
...  
Keyword(s):  
Reactive Intermediates ◽  
Heme Iron ◽  
Quinone Methide ◽  
Reaction Conditions ◽  
One Pot ◽  
Mild Conditions ◽  
Non Heme Iron ◽  
Common Strategy ◽  
Aqueous Conditions ◽  
Ortho Cresol

Generation of reactive intermediates and interception of these fleeting species in a cascade is a common strategy employed by Nature. However, formation of these species under mild conditions using traditional synthetic techniques can present a challenge. Here, we demonstrate the utility of biocatalysis in generating ortho-quinone methide intermediates under aqueous conditions and at reduced temperatures. Specifically, we applied an α-ketoglutarate-dependent non-heme iron enzyme, CitB, in the selective modification of benzylic C–H bonds of ortho-cresol substrates to afford a benzylic alcohol product which, under the reaction conditions, is in equilibrium with the corresponding ortho-quinone methide. Interception of the ortho-quinone methide by a nucleophile or a dienophile allows for one-pot conversion of benzylic C–H bonds into C–C, C–N, C–O, and C–S bonds in a chemoenzymatic cascade.

A sterically hindered salen iron complex as a model for active sites of mononuclear non-heme iron enzymes

2003 ◽  
Vol 96 (1) ◽  
pp. 133 ◽  
Author(s):  
Hiroshi FuiJii ◽  
Takuya Kurahashi ◽  
Manabu Sugimoto ◽  
Kenji Oda ◽  
Takashi Ogura
Keyword(s):  
Active Sites ◽  
Iron Complex ◽  
Heme Iron ◽  
Non Heme Iron ◽  
Iron Enzymes ◽  
Sterically Hindered
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