Oxygen atom transfer from carbonyl oxide to alkane catalyzed by metalloporphyrin

Article abstract of DOI:10.1016/j.tetlet.2009.03.046

The reaction of singlet oxygen with diazofluorene in the presence of metalloporphyrin caused oxidation of hydrocarbons as well as sulfide and anisol in substantial yields. The active oxidizing species is probably a high valency metal oxo species(M{double bond, long}O(porph)Cl) generated by an oxygen transfer from carbonyl oxide intermediate to M(porph)Cl.

Full text of DOI:10.1016/j.tetlet.2009.03.046

Tetrahedron Letters 50 (2009) 3585–3587
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Tetrahedron Letters
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Oxygen atom transfer from carbonyl oxide to alkane catalyzed
by metalloporphyrin
*
Masayuki Haranaka, Akiko Hara, Wataru Ando, Takeshi Akasaka
Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
The reaction of singlet oxygen with diazofluorene in the presence of metalloporphyrin caused oxidation
of hydrocarbons as well as sulfide and anisol in substantial yields. The active oxidizing species is probably
a high valency metal oxo species(M@O(porph)Cl) generated by an oxygen transfer from carbonyl oxide
intermediate to M(porph)Cl.
Received 15 January 2009
Revised 28 February 2009
Accepted 10 March 2009
Available online 13 March 2009
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Oxygen transfer
Carbonyl oxide
Metalloporphyrin
Active oxygen species
We present here evidence for oxygen atom transfer from car-
bonyl oxide to alkane as well as to sulfide and anisole catalyzed
by manganese or iron porphyrin. Carbonyl oxides are key interme-
diates in ozonolysis of alkenes1 (Scheme 1) and their reactivities
have been attracting attention from biological, atmospheric, and
chemical viewpoints.
In a typical experiment, a benzene solution of 9-diazofluorene
(3.7 ꢀ 10ꢁ2 M) and cyclohexane (100 equiv) was photoirradiated
at 15 °C with tetraphenylporphin (TPP, 7.0 ꢀ 10ꢁ4 M) as sensitizer,
and biphenyl (1.1 ꢀ 10ꢁ2 M) as internal standard under an oxygen
flow (flow rate; 2 mL/min) in the presence of Mn(TPP)Cl
(1.4 ꢀ 10ꢁ3 M).10 The resulting mixture was submitted to analytical
gas chromatography and gas chromatography—mass spectroscopy
(GC–MS). Cyclohexanol was apparently produced in 52% yield, to-
gether with fluorenone (Table 1, entry 1). All yields were based on
9-diazofluorene consumed. Very similar results were also obtained
with adamantane. 1-Adamantanol and 2-adamantanol were pro-
duced in 35% and 6.4% yields, respectively, together with fluorenone
(Table 1, entry 2). Control reactions reveal that all the components,
9-diazofluorene, 1O2,11 and metalloporphyrin, are essential for
The fundamental features of carbonyl oxides are fairly well
understood, as summarized in the comprehensive reviews pub-
lished during 1990s.2 On the other hand, formation of ozone in biol-
ogy has been suggested in very recent studies.3 Antibodies can
catalyze the generation of ozone from singlet oxygen (1O2) and
water. In spite of this new discovery in immune system, further
studies of the ozone reaction with various substrates may be dis-
turbed by not only high reactivity and short lifetime of ozone, but
also by the overlapping of the ozone signal with those of other gen-
erated molecules such as H2O2 in spectroscopic measurement. In
this context, we have used a well-known method to generate car-
bonyl oxide by oxidation of diazo compound with 1O2 (Scheme 2).
We report here for the first time the oxygen atom transfer of car-
bonyl oxide as one of the ozonolysis compounds in biological system
to metalloporphyrin as catalytic and biological model compound. In
our previous studies, metalloporpyrins have a strong affinity for the
intermediate peroxides such as persulfoxide4 and perepoxide5 to af-
ford the metal-oxo species (M@O), which is thought to be involved
in the model systems of cytochrome P-450 employing iron(III) por-
phyrin6 and conventional chemical oxidants such as iodosylbenzene
(PhIO),7 peracids,8 and hydroperoxide.9
O
O3
+
O
R
O
R
R
R
R
R
R
R
R
R
+
O
R
R
O
O
Scheme 1. Alkene ozonolysis.
O
1O2
N
N
O
R
R
+
R
R
+
N2
R
O
O
N2
R
* Corresponding author. Tel./fax: +81 29 853 6409.
E-mail address: akasaka@tara.tsukuba.ac.jp (T. Akasaka).
Scheme 2. 1O2 oxidation of diazo compound.
0040-4039/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2009.03.046

3586
M. Haranaka et al. / Tetrahedron Letters 50 (2009) 3585–3587
Table 1
Hydroxylation by diazofluorene/1O2/Mn(TPP)Cl system
O
N2
1O2 /Mn(TPP)Cl/alkane
+alcohol
OH
Entry
Reaction conditionsa
Alkane (equiv)
Diazo conv. (%)
Products, % yieldsb
OH
OH
1
2
3
4
5
6
Diazo/1O2/Mn
Diazo/1O2/Mn
Diazo/1O2/—
Diazo/1O2/—
—/1O2/Mn
76
76
85
97
—
52
—
0
—
35
—
0
—
6.4
—
0
100
17
100
—
0
17
—
0
—
0
—/1O2/Mn
—
—
7
Diazo/O2/Mn (dark)
14
—
0
0
17
a
The ratio of reactants was as follows: cyclohexane/diazofluorene/Mn(TPP)Cl (1.4 ꢀ 10ꢁ3 M) = 3000/30/1, and adamantane/diazofluorene/Mn(TPP)Cl (7.1 ꢀ 10ꢁ4 M) = 500/
30/1 in benzene (1 ml).
b
Yields are based on 9-diazofluorenone consumed. The reason why the conversion of the diazo compound as a sacrificial reagent is higher than the total yield of oxidized
products of alkane, is seemed to be self-degradation of 9-diazofluorenone.
hydroxylation. No degradation of the catalyst was observed. An oxy-
gen acceptor such as cyclohexane or adamantane is inert toward 1O2
and/or the carbonyl oxide. The photooxygenation of 9-diazofluorene
in the absence of metalloporphyrin gave the fluorenone quantita-
tively while no hydroxylation of cyclohexane or adamantane took
place (Table 1, entries 3 and 4). The results are summarized in Table
1.
Fe(TPFP)Cl/PhIO systems,12 respectively, and dissimilar to Fenton’s
reagent (<5% NIH Shift),15 may confirm the intermediacy of
FeIV@O(TPFP)+ÅClꢁ in the system.
Thianthrene 5-oxide can be used as a useful chemical monitor
for clarifying the character as the oxygen-transfer agent.2d,4,5,16
The carbonyl oxide intermediate derived from the 1O2 oxidation
of 9-diazofluorene acted as a nucleophile (XNu ꢂ 0.85) (Table 2, en-
try 1). As expected, the metal-oxo species Fe@O(TPFP)Cl derived
from the Fe(TPFP)Cl/PhIO system showed an essentially electro-
philic character (XNu ꢂ 0.42) (Table 2, entry 3). In the 1O2 oxidation
of 9-diazofluorene in the presence of Fe(TPFP)Cl, a less nucleophilic
oxygen-transfer reaction occurred toward thianthrene 5-oxide
(XNu ꢂ 0.57) (Table 2, entry 2). These results apparently reveal that
the oxidant produced in the 1O2 oxidation of 9-diazofluorene in the
presence of Fe(TPFP)Cl showed an essentially electrophilic charac-
ter together with the nucleophilic carbonyl oxide intermediate.
This suggests the intermediacy of FeIV@O(TPFP)+ꢃClꢁ in the system.
In conclusion, on the basis of these observations, the primary car-
bonyl oxide intermediate is likely to transfer an outer oxygen atom17
Both PhIO/Mn(TPP)Cl and the present 9-diazofluorene/1O2/
Mn(TPP)Cl systems have shown similar kinetic isotope effects in
the hydroxylation of a mixture of cyclohexane and cyclohexane-
d12 (kH/kD = 8.8 and 8.4, respectively). These observations may clar-
ify the intermediacy of the same metal-oxo species (Mn@O(TPP)Cl).
Moreover, (tetrakispentafluorophenylporphynato)iron chloride,
Fe(TPFP)Cl, known as one of the most electronegative metallopor-
phyrins, has catalyzed the oxygen transfer from the carbonyl oxide
intermediate to anisole-4-D to afford p-methoxyphenol.12 GC–MS
analysis of the resulting p-methoxyphenol showed 80% content of
deuterium, that is, 80% of the NIH shift.13 The marked NIH shift, sim-
ilar to 60% and 72% NIH shift observed with microsomes14 and

M. Haranaka et al. / Tetrahedron Letters 50 (2009) 3585–3587
3587
Table 2
Nucleophilic character (XNu) of oxygen-transfer agents derived from thianthrene 5-oxide
O
O
S
S
nucleophilic
oxidation
electrophilic
oxidation
nucleophilic oxidation
total oxidation
O
S
O
O
X
=
=
S
Nu
SSO
2
S
O
O
S
S
SSO + SOSO
2
2
electrophilic
oxidation
nucleophilic
oxidation
SSO
SOSO2
SSO + SOSO + 2SOSO
2
2
S
O
SOSO
Oxygen-transfer reactionsa
Active oxidant
Total yields %
Abs yields, mMb
XNu
Ref.
c
Entry
SSO2 nNu
SOSO nEl
SOSO2 nNu, nEl
1
2
3
4
9-Diazofluorene/1O2/CH2Cl2; 20 °C
[R2C@O+—Oꢁ]
15.1
2.7
13.9
3.08
11.89
1.48
3.53
3.86
0.08
1.11
6.17
19.6
2.36
trace
3.44
0.85
0.57
0.42
0.17
This work
This work
5
15
Fe(TPFP)Cl/9-diazofluorene/1O2/CH2Cl2; 20 °C
Fe(TPFP)Cl/PhIO/CH2Cl2; 20 °C
[M@O(porph)Cl]+[R2C@O+—Oꢁ]
[M@O(porph)Cl]
O3/CH2Cl2; ꢁ78 °C ? 20 °C
0.156
a
A trace of oxidized products of thianthrene 5-oxide was obtained in Fe(TPFP)Cl/1O2/CH2Cl2; 20 °C, 1O2/CH2Cl2; 20 °C, and PhIO/CH2Cl2; 20 °C systems.
b
The typical ratio of reactants, thianthrene 5-oxide/9-diazofluorene/PhIO/Fe(TPFP)Cl, is 80/30/20/1, [Fe(TPFP)Cl] = 1.2 ꢀ 10ꢁ3 M. Amount of conversion of thianthrene 5-
oxide into SSO2, SOSO, and SOSO2 products determined by GLC.
c
Mole fraction of amount of nucleophilic attack, that is, nNu/(nNu + nEl); SOSO2 represents double oxygen-transfer product either via the sequence
SSOðOX Þ ! SOSOðOX Þ ! SOSO2 or via the sequence SSOðOX Þ ! SSO2ðOX Þ ! SOSO2, so that the yield of SOSO2 is equally added to nNu and to nEl
.
Nu
Nu
El
El
N2
1O2
O
S
O
S
OH
OMe
O
M(porph)Cl
O
O
D
S
S
OH
(H)
O
O
S
OMe
O
O
S
S
M=O(porph)Cl
S
D
Scheme 3.
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to M(porph)Cl to afford M@O(porph)Cl, which can oxidize hydrocar-
bon, sulfide, and anisole to alcohol, sulfoxide, and methoxyphenol,
respectively (Scheme 3). The present findings may be of great help
in understanding the reaction of olefin and ozone as an oxidant in
synthetic application and the biological system.
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