Biomimetic oxidation of indole-3-acetic acid and related substrates with hydrogen peroxide catalysed by 5,10,15,20-tetrakis 2′,6′-dichloro-3′-sulfonatophenyl)porphyrinatoiron(III) hydrate in aqueous solution and AOT reverse micelles

Molecular Insights into the One-Carbon Loss Oxidation of Indole-3-acetic Acid

“…The evidence, along with our substructure-based scrutiny of the IAA-derived indoles, expanded our curiosity to the other driving force behind the IAA catabolism to address whether the IAA catabolic network (Scheme ) was more complex than proposed recently . As observed earlier, our EPR spin-trapping experiments failed to detect any nitrogen radical, but the carbon-centered counterparts that were conjectured to include skatolyl radical (R-1) and its resonance-stabilized isomer (R-2) (Figure A) were trapped . This suggested that the formation of resonance-stabilizable allylic radicals contributed to the LfDyP catalyzed oxidation of IAA but not indole-3-propionic and indole-3-butyric acids unable to form allylic radicals (Figure S28).…”

“…16 As observed earlier, 52 our EPR spin-trapping experiments failed to detect any nitrogen radical, but the carbon-centered counterparts that were conjectured to include skatolyl radical (R-1) and its resonance-stabilized isomer (R-2) (Figure 6A) were trapped. 53 Scheme 2. Proposed Mechanism Underlying the Oxidative Decarboxylation of IAA under the LfDyP Catalysis a a…”

Biomimetic Alkane Hydroxylations by an Iron(III) Porphyrin Complex with H2O2 and by a High-Valent Iron(IV) Oxo Porphyrin Cation Radical Complex

“…Iron(III) porphyrin complexes have been used as model compounds to mimic the chemistry of cytochrome P-450 enzymes that are capable of catalyzing a wide range of oxidation reactions including the remarkably difficult hydroxylation of unactivated C−H bonds of alkanes . Previous studies for iron(III) porphyrin complex-catalyzed alkane hydroxylation reactions have been conducted extensively with oxidants such as PhIO, KHSO 5 , NaOCl, ROOH, O 2 , and ozone. , However, as far as we have been able to discern, radical-free (enzyme mimetic) hydroxylation of alkanes with a biologically important oxidant (i.e., H 2 O 2 ) has been rarely observed in iron porphyrin-catalyzed oxygenation reactions. − Moreover, although high-valent iron(IV) oxo porphyrin cation radical species have been generally proposed as a reactive intermediate responsible for the C−H bond activation in cytochrome P-450 enzymes and iron porphyrin systems 1,2 and the presence of a high-valent iron oxo intermediate has been detected during the catalytic hydroxylation of ethylbenzene by ozone, direct hydroxylation reactions by “isolated” high-valent iron(IV) oxo porphyrin cation radical complexes have been rarely reported . In this note, we report that an electronegatively-substituted iron porphyrin complex efficiently catalyzes the hydroxylation of alkanes by H 2 O 2 via radical-free oxidation reactions in aprotic solvent (i.e., CH 3 CN) and that an “isolated” high-valent iron(IV) oxo porphyrin cation radical intermediate of the iron porphyrin complex is capable of activating C−H bonds of alkanes to give oxygenated products efficiently even at low temperature.…”