Catalytic oxidations using cobalt(II) complexes - Advances in Catalytic Activation of Dioxygen by Metal Complexes - page 309

This phenomenon has been termed oxygenated Fenton chemistry. It has
also been observed with in 4:1 MeCN/py, which effects
ketonization of the methylenic centers of cyclohexane, cyclohexene and
ethylbenzene 158-160 .

10. CATALYZED OXIDATIONS

10.1

Under Mukaiyama's conditions 161 , aromatic (benzoin,
4,4'-dimethylbenzoin and 4,4'-dimethoxybenzoin [anisoin]) are readily
oxidized by dioxygen at room temperature in the presence of excess
aldehyde or aldoacetal with catalytic amounts of or
under homogeneous conditions 162 . The stoichiometric equation is shown in
Figure 55.

Typical reaction conditions are: 1.2 mmol anisoin, 0.020 mmol

mmol
added initially, the remainder added dropwise over 1 hour at room
temperature). Yield of diketone 94%.

4 mL 1,2-dichloroethane, 3.6 mmol iso -butyraldehyde (0.9

10.2 Substituted phenols

The oxidation of substituted phenols has both biological and synthetic
relevance 163-166 . catalyzes the oxidation of substituted phenols Pa-
c by in the presence of 3-methylbutanal at 40°C in 1,2-dichloroethane
(Figure 56). No oxidation takes place in the absence of a catalyst. The major
oxidation product of 2,6-dimethylphenol is the corresponding
diphenoquinone DQa, whereas 2,6-di- t -butylphenol affords comparable
amounts of benzoquinone BQb and DQb. and act

similarly.