Functional model oxygenations by nonheme iron complexes - Advances in Catalytic Activation of Dioxygen by Metal Complexes - page 198

radical, 357-360 Barton et al. performed the radical trapping experiments 361-364 and led
the conclusion that the results obtained in the system of or can be
explained by radical chemistry and oxidation states of iron higher than are not
involved. 365 Oxygenation of nitroalkanes to the corresponding aldehydes or ketones
in relevance to 2-nitropropane dioxygenase was performed by ferroxime(II)
dimethylglyoxime)/TBHP in DMF or and both

radical species are thought to be involved in the H-abstraction

from nitroalkanes.
Barton et al. used bis(trimethylsilyl)peroxide for the

selective oxidation of alkanes to ketones using and
The intermediate formation of which reacts with a methylenic
carbon to form bond. By using this oxidant, it was found that
unlike the system, no extra ligand was needed if was used. 368 A
carbon radical from the manifold was proposed to explain the results.
Shyu et al. used sodium hypochlorite (NaOCl) for the epoxidation of cis-
stilbene with iron complexes with salicyladimine ligands, and
N , N' -(1,1-dimethylethylene)bis(salicylaldimine),
= N , N' -(1,1-dimethylethylene)bis(3-methoxysalicylaldimine). 369 The reaction

proceeded readily to produce trans- and cis -epoxides in good yield: 40%

yield with cis : trans = 20 : 80, 90% yield with cis : trans = 40 : 60.

4.4.2 Oxygenation by Mono-Iron Complexes/O 2 System
Monooxygenases catalyze incorporation of one atom of oxygen from
molecular oxygen into a substrate accompanied with the formation of water. In this
reaction the presence of electron and proton donors is required for activation of
molecular oxygen (eq. 9). Thus, selections of electron and proton donors as well as
iron complexes are key points for development of functional model Oxygenation
systems. There are some results, however, reporting monooxygenation in the
absence of electron and proton donors. These systems may not be regarded as
functional model systems, but worthy to notify their reactivity. Usually, mechanisms
are obscure in these systems. Shue et al. reported ketonization of methylenic
carbons such as cyclohexane by (DPAH: 2,6-dicarboxylatopyridine)/
and the dioxygenation of acetylenes, aryl olefins, and catechols as a reaction
mimics for dioxygenase. 370 The simple system was used
for Oxygenation of cyclohexene and methyl linoleate. 371 Catalyst complexes were
prepared in situ by mixing or in

MeCN with 2,2'-bipyridine, and was found the most reactive.

Oxygenation of cyclohexene was performed by complexes in aqueous