Nitrous oxide oxidation catalyzed by ruthenium porphyrin complex

Article abstract of DOI:10.1246/bcsj.77.1905

Dinitrogen oxide was employed as a clean oxidant for various oxidations in the presence of a catalytic amount of dioxoruthenium tetramesitylporphyrin complex (Ru(tmp)(O)₂). A variety of olefins, secondary alcohols, and benzyl alcohols were smoothly oxidized to the corresponding epoxides, ketones, and aldehydes in high yields. In the oxidation of 9,10-dihydroanthracene derivatives, the competitive reactions affording anthraquinones and anthracenes could be regulated by the reaction conditions. At a high temperature (200°C), anthraquinones were selectively produced, while the anthracenes were selectively produced by the addition of sulfuric acid.

Full text of DOI:10.1246/bcsj.77.1905

Ó 2004 The Chemical Society of Japan
Bull. Chem. Soc. Jpn., 77, 1905–1914 (2004) 1905
Nitrous Oxide Oxidation Catalyzed by Ruthenium Porphyrin Complex
Hirotaka Tanaka, Kentaro Hashimoto, Kyosuke Suzuki, Yasunori Kitaichi,
ꢀ
Mitsuo Sato, Taketo Ikeno, and Tohru Yamada
Department of Chemistry, Faculty of Science and Technology, Keio University,
Hiyoshi, Kohoku-ku, Yokohama 223-8522
Received April 12, 2004; E-mail: yamada@chem.keio.ac.jp
Dinitrogen oxide was employed as a clean oxidant for various oxidations in the presence of a catalytic amount of
dioxoruthenium tetramesitylporphyrin complex (Ru(tmp)(O)2). A variety of olefins, secondary alcohols, and benzyl al-
cohols were smoothly oxidized to the corresponding epoxides, ketones, and aldehydes in high yields. In the oxidation of
9,10-dihydroanthracene derivatives, the competitive reactionsꢁaffording anthraquinones and anthracenes could be regu-
lated by the reaction conditions. At a high temperature (200 C), anthraquinones were selectively produced, while the
anthracenes were selectively produced by the addition of sulfuric acid.
Much attention has been recently drawn to various oxides of
nitrogen, NOx such as NO,1 NO2, and N2O,2 because enor-
mous amounts of nitrogen monoxide (NO) or nitrogen dioxide
(NO2) have been emitted in the exhaust gas from internal-com-
bustion engines and industries causing serious air pollution.
Dinitrogen oxide (nitrous oxide, N2O) has been used in the
medical field as an anesthetic gas for a long time, whereas it
is recently regarded as one of the most influential greenhouse
gases.3 Nitrogen dioxide (NO2) in organic chemistry has been
produced industrially and is indispensable for nitration reac-
tion.4 On the other hand, nitrogen monoxide (NO)5 or dinitro-
gen oxide (N2O) has rarely been used in organic synthesis. Al-
though dinitrogen oxide is expected to work as a clean oxidant,
releasing only nitrogen gas as a by-product during the oxida-
tion reaction, it has seldom been employed as an oxidant be-
cause of the high activation energy required for its decompo-
sition to a nitrogen molecule and an oxygen atom.6 In order
for obstacles to its synthetic application to be overcome, dras-
tic reaction conditions, such as high temperature, high pres-
sure, or a super-critical phase, were generally required.7 In
the manufacturing process of 6,6-nylon, one of the practical
methods successfully introduced was as follows: dinitrogen
oxide emitted during the HNO3 oxidation of cyclohexane/cy-
clohexanol to adipic acid was reused for the oxidation of ben-
zene to phenol, which was then transformed into cyclohexa-
none/cyclohexanol by partial hydrogenation.8 Although the re-
cycling system for dinitrogen oxide is excellent, low energy ef-
ficiency and/or limited applicability of the functionalized
organic compounds have remained. Therefore, milder activa-
tion of dinitrogen oxides has been desired,9 and transition-met-
al complex catalysis is expected to be one of the most reliable
methods to decrease the activation energy. Because of its
strong affinity for electrons,10 dinitrogen oxide could be cap-
tured and reacted with the complexes with low valency metals.
Indeed, some stoichiometric reactions of dinitrogen oxide ox-
idation with transition-metal complexes were reported.11 In the
course of the studies on the reactivity of N2O, it was found that
dinitrogen oxide oxidation of phosphine to phosphine oxide
was catalyzed by a zero-valent nickel complex.12 Although
the catalytic oxidation of phosphines proceeded even at ꢂ40
ꢁC, the system could not be applied to the oxidation of organic
compounds. Hence, screening of various transition-metal com-
plexes revealed that ruthenium porphyrin complexes showed
catalytic activity for dinitrogen oxide oxidation. It was report-
ed by Groves that a dioxorutheniumporphyrin complex, pre-
pared by dinitrogen oxide oxidation from a ruthenium(II) com-
plex, could epoxidize 1-phenylpropene derivatives.13 A few
stoichiometric examples were reported, though the catalytic
system was not established.14 In this article, the catalytic dini-
trogen oxide oxidation in the presence of a catalytic amount of
the ruthenium complex for organic substrates is fully describ-
ed; e.g., epoxidation of olefins, oxidation of alcohols, and de-
hydrogenative aromatization of anthracenes proceeded using
dinitrogen oxide as an oxidant.
Results and Discussion
Ruthenium Porphyrin Complex Catalysis for Dinitrogen
Oxide Epoxidation. It is expected that transition-metal com-
plexes can capture and activate dinitrogen oxide to generate
the corresponding metal-oxo species while releasing nitrogen
and that the resulting metal-oxo complexes can oxidize organ-
ic substrates as shown in Fig. 1. On the basis of this concept,
the dinitrogen oxide oxidation of phosphine to phosphine ox-
ide was developed using a low valency nickel–dppp complex
catalyst,12 though this catalysis system could not be applied
to the oxidation of olefins or alcohols at all. Various kinds
of metal complexes were screened again after adopting the ep-
MLn
N2O
S[O]
Transition Metal
Complexes
O
N2
S
(Substrate)
MLn
Fig. 1. Catalytic cycle of N2O oxidation.
Published on the web October 9, 2004; DOI 10.1246/bcsj.77.1905

1906 Bull. Chem. Soc. Jpn., 77, No. 10 (2004)
Nitrous Oxide Oxidation
Table 1. Dioxoruthenium Porphyrin Complexes for N2O
Oxidation
Table 2. Solvent Effect for N2O Oxidation of Cholesteryl
Benzoate
C H
8 17
C H
8
C H
8 17
C H
8
17
17
cat.
Ru(tmp)(O)
2
cat.
Ru Complex
N O
N O
2
2
BzO
BzO
BzO
BzO
O
O
1a
2a
1a
2a
EntryaÞ Ru porphyrin complex Yield/% ꢁ-Selectivity/%
EntryaÞ
Solvent
Concentration/mM Yield/% ꢁ=ꢀbÞ
1
2
3
4
5
6
Ru(oep)(O)2
Ru(tpp)(O)2
Ru(tmpp)(O)2
Ru(tpfpp)(O)2
Ru(tdcpp)(O)2
Ru(tmp)(O)2
3a
3b
3c
3d
3e
3f
0
1
0
6
53
61
—
—
—
>99
>99
>99
1
2
3
4
5
6
7
8dÞ
THF
33
33
33
33
33
33
—
—
—
30
60
61
99
94
—
—
—
>99
>99
>99
>99
>99
EtOH
CH3CN
PhMe
PhH
PhF
PhF
14cÞ
14cÞ
a) All the reactions were carried out with 0.10 mmol choles-
teryl benzoate and 0.05 molꢁar amount ruthenium complex in
3 mL fluorobenzene at 100 C under 1:0 ꢃ 103 kPa (10 atm)
N2O for 3 h.
PhCl
a) Reaction conditions: 0.10 mmol of cholesteryl benzoate and
0.05 molar amount of Ru(tmp)(O)2 in solvent (3.0 mL) at 100
ꢁC under 1:0 ꢃ 103 kPa (10 atm) N2O for 3 h. b) Determined
by 1H NMR analysis. c) Reaction conditions: 0.20 mmol of
cholesteryl benzoate and 0.05 molar amount of Ru(tmp)(O)2
Et
Et
Ru(oep)
:
R3
N
1
2
3
Ru(tpp) : R = R = R = H
ꢁ
R1
R2
in 14 mL solvent. d) Reaction was performed at 140 C.
1
2
3
R
= R = H, R = OMe
Ru(tmpp) :
R2
R1
R1
R2
F
F
F
F
N
N
R3
Ru
R3
Ru(tpfpp) :
N
N
are shown in Table 2. Coordinating solvents, such as THF,
EtOH, and CH3CN, were not suitable for this reaction because
of their coordination with the ruthenium complex (Entries 1–
3). Aromatic solvents such as toluene and benzene gave better
yields (Entries 4 and 5), and fluorobenzene was found to be a
suitable solvent for this reaction (Entry 6).17 The concentration
in this reaction had a crucial effect on the yield. When the re-
action was performed at a lower concentration, the yield was
improved to 99% (Entry 7). It is assumed that a greater amount
of dinitrogen oxide dissolved in the solution would accelerate
the regeneration of the dioxoruthenium complex in the catalyt-
ic cycle. Under vigorous conditions in a chlorobenzene solvent
at 140 ꢁC, the product was obtained in a similar yield. The lat-
ter reaction conditions were more useful for less reactive sub-
strates than the conditions in Entry 7; therefore, they were
adopted as the standard for N2O epoxidation.
It was confirmed that the reaction did not proceed without
Ru(tmp)(O)2 (3f) or dinitrogen oxide. When substrate 1a
was treated under an argon atmosphere in the presence of
0.05 molar amount of 3f, the corresponding oxidized product
was obtained in only 9% yield. The oxygen atom of the epox-
ide was considered to be stoichiometrically transferred from
the dioxoruthenium complex. Because dinitrogen oxide of
99.999% purity was employed throughout the present work,
oxygen contamination was guaranteed to be less than 1.0
ppm, so that oxidation by contaminated oxygen was negligible.
For further confirmation, the evolution of nitrogen was moni-
tored by GC analysis as follows.
F
1
R2
R1
2
3
Ru(tdcpp) : R = R = Cl, R = H
1
2
3
R3
Ru(tmp) : R = R = R = Me
oxidation reaction of cholesteryl benzoate (1a) as a model
probe, because it was reported that cholesteryl esters were
preferentially epoxidized on their ꢀ-face using peroxy acid
as an oxidant, while their ꢁ-epoxides were selectively obtained
by the transition-metal oxo species.15 Because the dioxoruthe-
nium porphyrin complexes were preliminarily found to work
as a catalyst, various ruthenium porphyrin complexes were
first examined (Table 1). Using dioxoruthenium 2,3,7,8,12,13,
17,18-octaethylporphyrin (Ru(oep)(O)2, 3a), 5,10,15,20-tetra-
phenylporphyrin (Ru(tpp)(O)2, 3b), or 5,10,15,20-tetrakis(4-
methoxyphenyl)porphyrin (Ru(tmpp)(O)2, 3c), the reaction
did not proceed (Entries 1–3), although traces of the epoxide
were obtained in the presence of 5,10,15,20-tetrakis(penta-
fluorophenyl)porphyrin (Ru(tpfpp)(O)2, 3d) (Entry 4). In the
presence of 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin
(Ru(tdcpp)(O)2, 3e) or 5,10,15,20-tetramesitylporphyrin (Ru-
(tmp)(O)2, 3f), effective catalysts for aerobic oxidation,13b
the yield of the epoxides was greatly improved to 53–61%
yields with complete ꢁ-selectivity (Entries 5 and 6).16 As men-
tioned above, the ꢁ-selectivity in the present oxidation system
suggested that the dioxoruthenium complex was generated as
an intermediate for the epoxidation of the carbon–carbon dou-
ble bond of cholesteryl benzoate 1a.
Measurement of Nitrogen Gas Released during Dinitro-
gen Oxide Oxidation. During the dinitrogen oxide oxidation,
an equimolar amount of nitrogen gas based on the product
should be released. The amount of the evolved nitrogen gas
was measured in the epoxidation of cholesteryl benzoate
(1a). The analysis of the gas phase in the reaction vessel
Optimization of the Reaction Conditions for Epoxidation
of Cholesteryl Benzoate Catalyzed by Ru(tmp)(O)2 Com-
plex. Various solvents were examined for N2O epoxidation
of cholesteryl benzoate (1a) in the presence of a 0.05 molar
amount Ru(tmp)(O)2 (3f). The yields and stereoselectivities

H. Tanaka et al.
Bull. Chem. Soc. Jpn., 77, No. 10 (2004) 1907
was done as follows: the gas in the autoclave after the reaction
was collected in a flask and a small amount of carbon dioxide
was added as an internal standard. The thus obtained sample
was analyzed by GC attached to a TCD detector and a Porapak
Type Q column. As a result, about equimolar amount of nitro-
gen vs the substrate was detected in the N2O oxidation. It was
confirmed that dinitrogen oxide was employed as the oxidant.
N2O Epoxidation of Various Olefinic Compounds. The
dinitrogen oxide epoxidation catalyzed by the ruthenium com-
plex was successfully applied to various olefins (Table 3).
Cholesteryl esters, such as cholesteryl acetate (1b), decanoate
(1c), formate (1d), and ethyl carbonate (1e) were smoothly ep-
oxidized in high yield (Entries 1–4). The reaction of cholester-
yl bromide (1f) proceeded in 66% yield along with a small
amount of the debrominated product (Entry 5). Other sub-
strates containing a steroidal framework were also epoxidized
to give ꢁ-epoxides in high yields (Entries 6 and 7). Trisubsti-
tuted unfunctionalized olefins (1i–1j) could be smoothly ep-
oxidized in 86–90% yield (Etnries 8 and 9). The isolated car-
bon–carbon double bond in neryl acetate (1k) was selectively
epoxidized to afford the mono-epoxide 2k in good yield (Entry
10). Although the diepoxide 4l was observed in the epoxida-
Table 3. N2O Oxidation of Various Olefinic Compounds
Entrya)
Product
Substrate
Yield %
C H
8
17
C H
8
1
2
3
4
5
R = AcO−
1b
R = C9H19CO2−1c
R = HCO2− 1d
R = EtOCO2− 1e
2b
2c
2d
2e
2f
99
91
87
90
66
17
R
R
O
R = Br−
1f
COCH
3
COCH
3
1g
2g
2h
6
7
99
97
AcO
AcO
AcO
O
O
O
1h
AcO
O
O
2i
2j
86
90
64
8
9
1i
1j
O
10b)
2k
O
1k
1l
OAc
OAc
2l 44
4l 28
O
O
OTBDMS
OTBDMS
11
72
(total)
OTBDMS
O
12
13
2m
2n
94
94
OTBDMS
OTBDMS
1m
1n
O
O
OTBDMS
OTBDMS
a) Reaction conꢁditions: 0.2 mmol of olefins and 0.05 molar amount of Ru(tmp)(O)2 in 14 mL chloro-
benzene at 140 C under 1:0 ꢃ 103 kPa (10 atm) N2O. b) 0.085 molar amount catalyst was employed.

1908 Bull. Chem. Soc. Jpn., 77, No. 10 (2004)
Nitrous Oxide Oxidation
O
0.05 molar amount
Ru(tmp)(O)2
1.0x103 kPa N2O, Fluorobenzene, 100 °C
87%
O
0.05 molar amount
O
Ru(tmp)(O)2
+
1.0x103 kPa N2 or O2, Fluorobenzene, 100 °C
Trans
Cis
N2O
O2
38% yield Cis:Trans = >1:99
42% yield Cis:Trans = 87:13
Scheme 1.
0.05 molar amount
Ru(tmp)(O)
2
+
CHO
11 23
Ru(tmp)CO
C
H
OH
C
H
12 25
3
1.0x10 kPa N O
2
5t
6t
25% yield
7
1,2-dichloroethane, 120 °C
67% yield based
on Ru(tmp)(O)
2
Scheme 2.
O
0.05 molar amount
3
Ru(tmp)(O)
2
+
1.0x10 kPa N O, Benzene, 120 °C
2
O
17%
56 %
9a
8a
10a
Scheme 3.
tion of the t-butyldimethylsilyl (TBDMS) ether of nerol (1l),
the isolated carbon–carbon double bond was preferentially oxi-
dized (Entry 11). The TBDMS ether of citronelol (1m) was
converted to the corresponding epoxide in high yield (Entry
12). The reaction could be applied to a reactive disubstituted
olefin (1n) (Entry 13). Although the yields of most of the di-
and monosubstituted olefins were low, the oxidation of ace-
naphthylene and cis-stilbene gave acenaphthenone, a rear-
ranged product from the epoxide, and trans-stilbene oxide in
87% and 38% yield, respectively (Scheme 1). When molecular
oxygen was used instead of dinitrogen oxide for epoxidation of
cis-stilbene under the same conditions, cis-stilbene oxide was
preferentially obtained (cis=trans ¼ 87=13). The results indi-
cated that the lifetime of the Ru(II) porphyrin complex was
longer in dinitrogen oxide than in an oxygen atmosphere;
hence, the rearrangement and isomerization caused by the
Ru(II) or Ru(IV) porphyrin complex occurred more easily.18
Optimization of the Reaction Conditions for N2O Oxida-
tion of Alcohols. The present system was next subjected to
the oxidation of alcohols, using 2-naphthalenemethanol (5a)
as a model substrate. Because the solvents have a crucial effect
on the N2O epoxidation, various solvents were reexamined for
optimization (Table 4). In aromatic solvents, which were suit-
able for epoxidation, 5a was converted to the corresponding al-
dehyde 6a in 39–62% yield (Entries 1–3). Although the yields
were moderate in dichloromethane and chloroform (Entries 4
and 5), they were greatly improved in 1,2-dichloroethane
Table 4. Optimization of the Reaction Conditions for N2O
Oxidation of Alcohols
O
cat.
Ru(tmp)(O)
2
OH
H
N O
2
5a
6a
EntryaÞ
Solvent
Temp/ꢁC
Conv/%
Yield/%
1
2
3
4
5
PhH
PhF
PhCl
CH2Cl2
CHCl3
100
100
100
100
100
41
62
41
23
33
41
62
39
22
32
Cl
6
100
120
71
71
Cl
7bÞ
100
quant
a) Reaction conditions: 0.30 mmol of 2-naphthalenemethanol
and 0.05 molar amount of Ru(tmp)(O)2 in solvent (14.0 mL)
under 1:0 ꢃ 103 kPa (10 atm) of N2O for 6 h. b) For 9 h.
(Entry 6). The aldehyde was obtained in aꢁquantitative yield
when the reaction was carried out at 120 C for 9 h in 1,2-
dichloroethane (Entry 7). In all cases, no carboxylic acid
was observed.
Scope and Limitation of N2O Oxidation of Various
Alcohols. A variety of alcohols was successfully oxidized
in this system (Table 5). Secondary benzyl alcohols 5b–5i

H. Tanaka et al.
Bull. Chem. Soc. Jpn., 77, No. 10 (2004) 1909
Table 5. N2O Oxidation of Various Alcohols
were smoothly converted to the corresponding ketones 6b–6i
in excellent yields in the presence of 0.05 molar amounts of
Ru(tmp)(O)2 (3f) (Entries 1–8). ꢁVarious secondary alkanols
5j–5o were also oxidized at 150 C to give the corresponding
alkyl ketones 6j–6o in high yields (Entries 9–14). Interesting-
ly, an ꢀ,ꢁ-unsaturated ketone 6p, 6q was selectively obtained
from 4-phenyl-3-buten-2-ol (5p) or cholest-4-en-3-ol (5q)
without any epoxidation of the carbon–carbon double bond
(Entries 15 and 16). Like 2-naphthalenemethanol (5a), other
benzylic primary alcohols such as 1-naphthalenemethanol
(5r) and benzyl alcohol (5s) were selectively oxidized to the
corresponding aldehydes 6r and 6s (Entries 17 and 18).
The oxidation of 1-dodecanol (5t) as a primary alkanol was
then attempted under the reaction conditions, but dodecanal
(6t) was obtained in only 25% yield, and the ruthenium com-
plex was recovered as the tetramesitylporphyrin carbonyl com-
plex (Ru(tmp)(CO)) (7) (Scheme 2). The low reactivity for pri-
mary alkanols could be similarly ascribed to the low yield in
the epoxidation of a terminal olefin with molecular oxygen;19
e.g., the reaction of an aldehyde and the Ru(II) porphyrin
complex produced an inactive Ru(II)CO porphyrin complex.
Indeed, 67% of 7 was recovered after the reaction of 1-dode-
canol.
N2O Oxidation of 9,10-Dihydroanthracene. Next, 9,10-
dihydroanthracene (8a) was subjected to dinitrogen oxide ox-
idation for examination of C–H oxidation. When the reaction
was carried out in the presence oꢁf a 0.05 molar amount
Ru(tmp)(O)2 (3f) in benzene at 120 C under 10 atm of dini-
trogen oxide atmosphere, a mixture of anthraquinone (9a)
and anthracene (10a) was obtained in moderate yield
(Scheme 3). In order to achieve the respective selectivities
for anthraquinone (9a) and anthracene (10a), a reaction path-
way was assumed (Fig. 2). Anthracene was first oxidized at
the C–H bond to generate benzyl alcohol 11a,20 and then de-
hydration from alcohol 11a gave anthracene (10a). On the oth-
er hand, the consecutive oxidation of alcohol 11a via 14a
would afford the quinone 9a. Based on this hypothesis, vigor-
ous conditions might accelerate the formation of quinone be-
cause many oxidation steps were required for the production
of quinone. According to the results of the examination of var-
ious solvents and temperature (Table 6), it was found that the
solvents had a great influence on the ratio of anthraquinone
(9a) vs anthracene (10a). For example, almost equal amounts
of 9a and 10a were obtained in hydrocarbon solvents such as
cyclohexane or decaline (Entries 1 and 2), while anthracene
was preferentially obtained in halogenated solvents (Entries
3–5). Anthraquinone was preferentially obtained in aromatic
solvents such as chlorobenzene or benzene (Entries 6 and 7).
The reaction temperature was then examined for the benzene
solvent. It was found that the higher the temperature was,
the more anthraquinone was produced. Finally,ꢁanthraquinone
was obtained in 90% yield in benzene at 200 C (Conditions
A).
Entrya)
Yield %
92c)
Product
O
1
6b
O
2
3
6c
94
O
quant
6d
Ph
O
O
6e
4
96
5b)
6
6f
quant
99
O
6g
O
7
8
6h
6i
99
95
O
O
9b)
98
97
6j
O
10b)
6k
O
11b)
12b)
6l
89
97
6m
Ph
O
O
13b)
6n
86
O
14b)
15
6o
6p
97
89
O
C H
8
17
6q
quant
16
O
CHO
CHO
17
18
6r
6s
92
Optimization of the reaction conditions for the selective
synthesis of anthracene was next examined. In Table 6, anthra-
cene was preferentially obtained in halogenated solvents. It
was assumed that an acid generated by the decomposition of
the solvents should enhance the production of anthracene. That
is, an acid protonated the hydroxy group of 9,10-dihydroan-
95c)
a) Reaction conditions: 0.3 mmol of alcohols and 0.05 moꢁlar
amount of Ru(tmp)(O)2 in 14 mL 1,2-dichloroethane at 120 C
under 1:0 ꢃ 103 kPa (10 atm) N2O. b) At 150 C. c) GC yield.
ꢁ

1910 Bull. Chem. Soc. Jpn., 77, No. 10 (2004)
Nitrous Oxide Oxidation
Table 7. Optimization for the Synthesis of Anthracene
O
cat.
Ru(tmp)(O)
2
8a
[O]
OH
N O, Benzene
2
120 °C, 4 h
H O
2
O
9a
8a
10a
Yield/%
EntryaÞ
Additive
11a
10a
9a
10a
[O]
OH
Aromatized product
1
2
3
TsOH
CH3CO2H
CF3CO2H
HCldÞ
0
0
1
19
32
16
24
11
99
9
O
4
0
and/or
5
6
7bÞ
8cÞ
9
HBr
H2SO4
H2SO4
H2SO4
2
0
0
0
16
23
0
OH
[O]
12a
13a
5
FeSO4/7H2O
CuSO4/5H2O
Ce(SO4)2/4H2O
77
74
90
O
10
11
a) Reaction conditions: 0.15 mmol of 9,10-dihydroanthracene
and 0.05 molar amount of Ru(tmp)(O)2 in solvent (14.0 mL)
under 1:0 ꢃ 103 kPa (10 atm) of N2O. b) Under 1:0 ꢃ 103
kPa (10 atm) of argon. c) Without catalyst. d) 1.0 mol/L ether
solution.
OH
14a
[O]
O
Oxidized product
of benzylic carbon
of anthraquinone, although most of the acids also decreased
the yield (Entries 1–5). It was assumed that the counter anions
of the acids could coordinate with the ruthenium complex and
deactivate it. Because of the relatively low coordination ability
of sulfonate, sulfuric acid was then examined to afford the an-
thracene quantitatively (Entry 6, Conditions B). It was con-
firmed that aromatization did not proceed only with sulfuric
acid in the absence of N2O or the catalyst (Entries 7 and 8).
Because sulfonate was found to be as an efficient counter
anion, several metal sulfonates were examined as additives.
Most of the metal sulfonates varied the ratio of anthracene
vs anthraquinone, and cerium sulfonate was the most effective
additive for anthracene selectivity among them (Entries 9–11).
Many additives, such as 1-methylimidazole,21 HCl/HBr,22 or
carboxylic acid,23 were reported for aerobic oxidation using
metal porphyrins or related metal complexes; however, the
combined use of the ruthenium porphyrin complex with sulfu-
ric acid or some metal sulfonates was novel.
N2O Oxidation of 9,10-Dihydroanthracene Derivatives.
The oxidation of various substrates was attempted under the
optimized reaction conditions A and B (Table 8); Condition
A was suitable for the oxidation of benzylic carbon into the
corresponding carbonyl group, and condition B was suitable
for dehydrogenative aromatization. Fluorene (8b) was smooth-
ly oxidized to the corresponding ketone 9b under condition A
(Entry 1). This reaction was not prevented by the presence of
ether or the sulfide moiety in substrates. When xantene (8c) or
thioxantene (8d) was used as a substrate, the corresponding ke-
tone 9c or 9d was obtained in good-to-high yield (Entries 2
and 3). In Entry 3, C–H oxidation of the carbon atom was more
preferable than the oxidation of sulfur, though the oxidized
product of the sulfur atom was present in 15% yield. When
2-methyl-9,10-dihydroanthracene (8e) was employed, 2-meth-
O
9a
Fig. 2. Reaction pathway from 9,10-dihydroanthracene to
anthraquinone and anthracene.
Table 6. Optimization for the Synthesis of Quinone
O
cat.
Ru(tmp)(O)
2
N O
2
O
9a
8a
10a
Yield/%
EntryaÞ
Solvent
Temp/ꢁC Time/h
9a
10a
1
2
3
4
cyclohexane
decaline
CH2Cl2
160
160
160
160
4
4
4
4
27
29
8
55
44
41
13
CHCl3
—
Cl
Cl
5
160
4
34
57
6
7
8
9bÞ
chlorobenzene
benzene
benzene
160
160
120
200
4
4
4
20
62
57
17
90
38
34
56
9
benzene
a) Reaction conditions: 0.15 mmol of 9,10-dihydroanthracene
and 0.05 molar amount of Ru(tmp)(O)2 in solvent (14.0 mL)
under 1:0 ꢃ 103 kPa (10 atm) of N2O. b) 0.10 molar amount
of catalyst.
thracen-9-ol (11a) intermediate and accelerated the dehydra-
tion. Hence, various acids were examined as additives
(Table 7). All of the acidic additives suppressed the production

H. Tanaka et al.
Bull. Chem. Soc. Jpn., 77, No. 10 (2004) 1911
Table 8. N2O Oxidation of 9,10-Dihydroanthracene Derivatives
Entrya)
Substrate
Conditionsa,b)
Product
Yield %
O
A
1
8b
8c
8d
8e
9b
9c
9d
9e
85
O
A
A
92
75
88
2
3
4
O
S
O
O
S
O
A
B
A
O
O
5
6
10e
9f
98
98
Et
Et
Et
8f
O
O
10f
99
7
B
8g
8h
A
B
A
9g
86
96
8
9
O
10g
Et
Et
47c)
10
9h
O
Et
95d)
11
B
10h
a) Conditions A: 0.05 mmol of substrates and 0.10 molar amount of Ru(tmp)(O)2 in 14
mL benzene at 200 ꢁC under 1:0 ꢃ 103 kPa (10 atm) N2O. b) Conditions B: 0.15 mmol
of substrates and 0.05 molar amount of Ru(tmp)(O)2 in 14 mL benzene with 1.0 molar
ꢁ
amount of H2SO4 at 120 C under 1:0 ꢃ 103 kPa (10 atm) N2O. c) 42% of anthraqui-
none was obtained. d) 0.10 molar amount of catalyst.
ylanthraquinone (9e) and 2-methylanthracene (10e) were
selectively obtained (Entries 4 and 5). Similarly, from various
alkyl-group-substituted 9,10-dihydroanthracenes, anthraqui-
nones and anthracenes could be selectively obtained only by
the reaction conditions (Entries 6–11).
Experimental
Dinitrogen oxide with 99.999% purity was purchased from Air
Liquid Japan Ltd. Cholesteryl benzoate (1a), cholesteryl acetate
(1b), cholesteryl decanoate (1c), cholesteryl formate (1d), choles-
teryl ethyl carbonate (1e), cholesteryl bromide (1f), pregrenolone
acetate (1g), androsterone acetate (1h), and neryl acetate (1k)
were purchased from Tokyo Kasei Kogyo (TCI) Co., Ltd.
1-(tert-Butyldimethylsiloxy)-3,7-dimethyl-2,6-octadiene (1l),
1-(tert-butyldimethylsiloxy)-3,7-dimethyl-6-octene (1m), and
5-(tert-butyldimethylsiloxymethyl)bicyclo[2.2.1]hept-2-ene (1n)
were prepared by a reported method.24 1-Phenylethanol (5b), 9-
fluorenol (5h), 1-acenaphthenol (5i), 2-adamantanol (5n) were
purchased from Tokyo Kasei Kogyo (TCI) Co., Ltd. Benzyl alco-
Conclusion
In summary, it was revealed that the ruthenium porphyrin
complex catalyzed dinitrogen oxide oxidation. That is, the ep-
oxidation of olefins, the oxidation of alcohols to the corre-
sponding aldehydes and ketones, and dehydrogenative aroma-
tization smoothly proceeded using dinitrogen oxide as an oxi-
dant.

1912 Bull. Chem. Soc. Jpn., 77, No. 10 (2004)
Nitrous Oxide Oxidation
hol (5s) was purchased from Wako Pure Chemical Industries, Ltd.
1-Dodecanol (5t) was purchased from Kanto Chemical Co., Inc.
2-Naphthylmethanol (5a), 1-(2-naphthyl)ethanol (5c), 1-[1,10-bi-
phenyl]-4-ylethanone (5d), diphenylmethanol (5e), 1-phenyl-1-
butanol (5f), 1,2,3,4-tetrahydro-1-naphthol (5g), 4-phenyl-2-buta-
nol (5j), 2-undecanol (5k), 4-decanol (5l), 4-phenylcyclohexanol
(5m), cyclododecanol (5o), trans-4-phenyl-3-buten-2-ol (5p),
cholest-4-en-3-ol (5q), and 1-naphthylmethanol (5r) were pre-
pared by the reduction of the corresponding ketones or aldehydes
with sodium borohydride. 9,10-Dihydroanthracene (8a) and fluo-
rene (8b) were purchased from Tokyo Kasei Kogyo (TCI) Co.,
Ltd. Xanthene (8c) was purchased from Kanto Chemical Co.,
Inc. Thioxanthene (8d) was prepared by the reduction of 9H-thi-
oxanthene-9-one. 2-Methyl-9,10-dihydroanthracene (8e), 2-ethyl-
9,10-dihydroanthracene (8f), 2,3-dimethyl-9,10-dihydroanthra-
cene (8g), and 9-ethyl-9,10-dihydroanthracene (8h) were prepared
by a reported method.25
5,6-ꢀ-Epoxycholesteryl Acetate (2b):26 1H NMR (400 MHz)
ꢂ 4.70 (1H, m), 3.01 (1H, s), 2.07–1.80 (6H, m), 1.76–1.73 (2H,
m), 1.51–0.91 (26H, m), 0.89–0.80 (9H, m), 0.57 (3H, s).
5,6-ꢀ-Epoxycholesteryl Decanoate (2c):26
1H NMR (400
MHz) ꢂ 4.80 (1H, m), 3.09 (1H, m), 2.21–0.57 (62H, m).
5,6-ꢀ-Epoxycholesteryl Formate (2d):26
MHz) ꢂ 7.95 (1H, s), 4.84 (1H, m), 3.02 (1H, s), 2.13–0.57
(43H, m).
1H NMR (400
5,6-ꢀ-Epoxycholesteryl Ethyl Carbonate (2e):26 1H NMR
(400 MHz) ꢂ 4.56 (1H, m), 4.11 (2H, m), 3.01 (1H, s), 2.14–
0.57 (46H, m).
5,6-ꢀ-Epoxycholesteryl Bromide (2f):27
1H NMR (400
MHz) ꢂ 3.97 (1H, m), 3.06 (1H, s), 2.53 (1H, m), 2.12–0.85
(39H, m), 0.63 (3H, s).
5,6-ꢀ-Epoxypregnanone Acetate (2g):28
1H NMR (400
MHz) ꢂ 4.78 (1H, m), 3.09 (1H, d, J ¼ 2:4 Hz), 2.49 (1H, t, J ¼
9:2 Hz), 2.18–1.96 (12H, m), 1.83–0.66 (16H, m), 0.59 (3H, s).
5,6-ꢀ-Epoxyandrostanone Acetate (2h):29
Preparation of 2-Methyl-2-dodecene (1i). Bromodecane (36
g, 0.16 mol) and triphenylphosphine (50 g, 0.19 mol) were dis-
1H NMR (400
MHz) ꢂ 4.71 (1H, m), 3.08 (1H, d, J ¼ 2:4 Hz), 2.40 (1H, dd,
J ¼ 19:2, 8.8 Hz), 2.16–1.10 (20H, m), 0.97 (3H, s), 0.78 (3H,
s), 0.62 (1H, m).
2,3-Epoxy-2-methyldodecane (2i): 1H NMR (400 MHz) ꢂ
2.71 (1H, t, J ¼ 5:9 Hz), 1.60–1.26 (22H, m), 0.90 (3H, t, J ¼
6:6 Hz); 13C NMR (100 MHz) ꢂ 64.6, 58.2, 32.0, 30.7, 29.58,
29.57, 29.4, 28.9, 26.6, 25.0, 22.8, 18.8, 14.2; IR (NaCl) 2927,
ꢁ
solved in benzene (100 mL) and stirred at 100 C for 40 h. Ben-
zene was removed in vacuo, and the phosphonium salt was ob-
tained quantitatively. To a suspension of the phosphonium salt
in 150 mL of THF, acetone (24 mL, 0.33 mol) and potassium
tert-butoxide (19.2 g, 0.17 mol) were added and stirred for 20 h
at room temperature. The mixture was diluted with 250 mL of
hexane; then the white precipitate appeared. The precipitate was
removed by filtration, and next the filtrate was concentrated.
The residue was distilled to give pure 2-methyl-2-dodecene
(17.9 g, 60% yield). b.p. 75–77 ꢁC/467 Pa (3.5 mmHg); 1H NMR
(400 MHz) ꢂ 5.09 (1H, m), 1.94 (2H, br), 1.69 (3H, s), 1.60 (3H,
s), 1.26 (14H, m), 0.88 (3H, t, J ¼ 6:62 Hz); 13C NMR (100 MHz)
ꢂ 124.9, 100.5, 32.0, 30.0, 29.72, 29.69, 29.4, 28.3, 28.1, 25.8,
22.8, 17.8, 14.2; IR (NaCl) 2926, 2855, 2360, 2253, 1465, 1378,
911, 740, 651 cmꢂ1; HRMS Calcd for C13H26: (Mþ), 182.2035.
Found: m=z 182.2041.
2856, 2252, 1467, 1379, 1250, 1120, 913, 742, 650, 470 cmꢂ1
;
HRMS Calcd for C13H26O: (Mþ), 198.1984. Found: m=z
198.1972.
2-Nonyl-1-oxaspiro[2.5]octane (2j): 1H NMR (400 MHz) ꢂ
2.70 (1H, t, J ¼ 5:9 Hz), 1.80–1.20 (26H, m), 0.88 (3H, m);
13C NMR (100 MHz) ꢂ 64.5, 62.3, 36.1, 32.2, 30.0, 29.91,
29.89, 29.8, 29.7, 28.6, 27.2, 26.1, 25.5, 25.4, 23.0, 14.4; IR
(NaCl) 2929, 2857, 2252, 1457, 1378, 909, 736, 651 cmꢂ1; HRMS
Calcd for C16H30O: (Mþ), 238.2297. Found: m=z 238.2311.
6,7-Epoxy-3,7-dimethyl-2-octenyl Acetate (2k):30 1H NMR
(400 MHz) ꢂ 5.41 (1H, t, J ¼ 6:6 Hz), 4.58 (2H, d, J ¼ 6:6
Hz), 2.71 (1H, t, J ¼ 6:3 Hz), 2.26 (2H, t, J ¼ 7:8 Hz), 2.05
(3H, s), 1.78 (3H, s), 1.63 (2H, dt, J ¼ 7:8, 6.3 Hz), 1.31 (3H,
s), 1.27 (3H, s).
1-(tert-Butyldimethylsiloxy)-6,7-epoxy-3,7-dimethyl-2-octene
(2l): 1H NMR (400 MHz) ꢂ 5.29 (1H, t, J ¼ 6:4 Hz), 4.11 (2H, d,
J ¼ 6:0 Hz), 2.63 (1H, t, J ¼ 6:4 Hz), 2.11 (2H, m), 1.67 (3H, s),
1.55 (2H, m), 1.24 (3H, s), 1.20 (3H, s), 0.83 (9H, s), 0.00 (6H, s);
13C NMR (100 MHz) ꢂ 136.3, 125.7, 63.9, 59.8, 58.4, 28.9, 27.5,
26.1, 24.9, 23.4, 18.8, 18.5, ꢂ5:0; IR (NaCl) 2959, 2857, 2253,
1463, 1380, 1255, 1058, 911, 740 cmꢂ1; HRMS Calcd for
C16H32O2Si: (Mþ), 284.2172. Found: m=z 284.2189.
1-(tert-Butyldimethylsiloxy)-2,3:6,7-diepoxy-3,7-dimethyl-2-
octane (4l): 1H NMR (400 MHz) ꢂ 3.66 (2H, dd, J ¼ 5:2, 4.8
Hz), 2.82 (1H, t, J ¼ 5:6 Hz), 2.64 (1H, t, J ¼ 5:6 Hz), 1.66–
1.51 (4H, m), 1.25 (3H, s), 1.23 (3H, s), 1.19 (3H, s), 0.81 (9H,
s), 0.00 (3H, s), ꢂ0:01 (3H, s); 13C NMR (100 MHz) ꢂ 64.2,
63.9, 61.8, 60.4, 58.4, 29.8, 25.9, 25.1, 24.9, 22.1, 18.7, 18.3,
ꢂ5:2; IR (NaCl) 2959, 2930, 2253, 1471, 1382, 1256, 1092,
909, 736 cmꢂ1; HRMS Calcd for C16H32O3Si: (Mþ), 300.2121.
Found: m=z 300.2112.
1-(tert-Butyldimethylsiloxy)-6,7-epoxy-3,7-dimethyloctane
(2m): 1H NMR (400 MHz) ꢂ 3.61 (2H, m), 2.65 (1H, t, J ¼ 6:4
Hz), 1.57–1.27 (7H, m), 1.26 (3H, s), 1.22 (3H, s), 0.84 (12H, s),
0.00 (6H, s); 13C NMR (100 MHz) ꢂ 64.7, 61.3, 58.3, 39.8, 33.7,
29.4, 26.5, 26.0, 25.0, 19.6, 18.8, 18.4, ꢂ5:2; IR (NaCl) 2958,
2929, 2251, 1462, 1379, 1255, 1095, 909, 738 cmꢂ1; HRMS
Preparation of Decylidenecyclohexane (1j). Olefin (1j) was
prepared from cyclohexanone and bromodecane under the same
conditions as for the synthesis of 1i (66% yield). b.p. 126 ꢁC/
1
573 Pa (4.3 mmHg); H NMR (400 MHz) ꢂ 5.06 (1H, t, J ¼ 7:3
Hz), 2.13–1.94 (6H, m), 1.56–1.45 (6H, m), 1.35–1.20 (14H,
m), 0.88 (3H, t, J ¼ 6:8 Hz); 13C NMR (100 MHz) ꢂ 139.3,
121.5, 37.2, 32.0, 30.3, 29.70, 29.65, 29.4, 29.3, 28.8, 28.7,
27.9, 27.12, 27.05, 22.8, 14.2; IR (NaCl) 2927, 2854, 2253,
1467, 1380, 910, 733, 651 cmꢂ1; HRMS Calcd for C16H30:
(Mþ), 222.2347. Found: m=z 222.2377.
Preparation of Dioxoruthenium Tetramesitylporphyrin
Complex (3f). Complex 3f was prepared by a reported meth-
od.13b
General Procedure for Epoxidation of Olefins Using Dini-
trogen Oxide. To a chlorobenzene solution of Ru(tmp)(O)2
(3f, 21 mg, 0.023 mmol) in an autoclave, 2-methyl-2-dodecene
(1i, 50 mg, 0.27 mmol) was added under a dinitrogen oxide atmo-
sphere. After the solvent amount was fixed at 14 mL, the reaction
mixture was heated to 140 ꢁC under 1:0 ꢃ 103 kPa (10 atm) of
N2O for 5 h. The desired epoxide (2i) was purified by silica gel
column chromatography (Hexane:EtOAc 20:1, 86% yield).
Spectral Data. The spectral data of obtained epoxides 2a, 2b,
2c, 2d, 2e, 2f, 2g, 2h, and 2k were in good agreement with liter-
ature.
5,6-ꢀ-Epoxycholesteryl Benzoate (2a):26
1H NMR (400
MHz) ꢂ 8.02 (2H, m), 7.55 (1H, t, J ¼ 7:3 Hz), 7.43 (2H, t, J ¼
7:3 Hz), 5.03 (1H, m), 3.12 (1H, s), 2.32–0.65 (43H, m).

H. Tanaka et al.
Bull. Chem. Soc. Jpn., 77, No. 10 (2004) 1913
Calcd for C16H34O2Si: (Mþ), 286.2328. Found: m=z 286.2288.
5-(tert-Butyldimethylsiloxymethyl)-2,3-epoxybicyclo[2.2.1]-
heptane (2n): 1H NMR (400 MHz) ꢂ 3.57–3.45 (2H, m), 3.18
(1H, d, J ¼ 2:8 Hz), 3.06 (1H, d, J ¼ 2:8 Hz), 2.51 (1H, t, J ¼
1:6 Hz), 2.42 (1H, dd, J ¼ 3:6, 1.6 Hz), 2.16–2.08 (1H, m),
1.64–1.57 (1H, m), 1.31 (1H, dd, J ¼ 9:6, 2.0 Hz), 0.85 (9H, s),
0.73–0.68 (2H, m), 0.00 (6H, s); 13C NMR (100 MHz) ꢂ 63.7,
51.4, 49,7, 43.7, 38.0, 37.2, 28.1, 27.1, 25.9, 18.3, ꢂ5:2; IR
(NaCl) 2956, 2858, 2253, 1471, 1387, 1255, 1095, 910, 741
cmꢂ1; HRMS Calcd for C14H26O2Si: (Mþ), 254.1702. Found:
m=z 254.1702.
General Procedure for Oxidation of Alcohols Using Dinitro-
gen Oxide. To a 1,2-dichloroethane solution of Ru(tmp)(O)2 (3f,
13 mg, 0.015 mmol) in an autoclave, a solution of 1-(2-naphthyl)-
ethanol (5c, 50 mg, 0.29 mmol) was added under a dinitrogen ox-
ide atmosphere. After the solvent amount was fixed at 14 mL, the
reaction mixture was heated to 120 ꢁC under 1:0 ꢃ 103 kPa (10
atm) of N2O for 7.5 h. The desired ketone (6c) was purified by
silica gel column chromatography (Hexane:Et2O 10:1, 94%
yield).
T. F. Stocker, D. Raynaud, and J.-M. Barnola, Science, 285, 227
(1998). c) G. Centi, S. Perathoner, and F. Vazzana, CHEMTECH,
29, 48 (1999). d) M. A. K. Khalil, Annu. Rev. Energy Environ., 24,
645 (1999).
4
For example: a) W. Steinkopf and U. Kuhnel, Chem. Ber.,
75, 1323 (1942). b) H. Suzuki, T. Murashima, I. Kozai, and T.
Mori, J. Chem. Soc., Perkin Trans. 1, 1993, 1591. c) N. Nishiwaki,
S. Sakaguchi, and Y. Ishii, J. Org. Chem., 67, 5663 (2002).
5
For example: a) T. Mukaiyama, E. Hata, and T. Yamada,
Chem. Lett., 1995, 505. b) E. Hata, T. Yamada, and T.
Mukaiyama, Bull. Chem. Soc. Jpn., 68, 3629 (1995). c) T. Itoh,
Y. Matsuya, K. Nagata, and A. Osawa, Tetrahedron Lett., 37,
4165 (1996). d) J. A. Hrabie and L. K. Keefer, Chem. Rev.,
102, 1135 (2002). e) T. Sugihara, K. Kuwahara, A. Wakabayashi,
H. Takao, H. Imagawa, and M. Nishizawa, Chem. Commun.,
2004, 216.
6
7
W. M. Graven, J. Am. Chem. Soc., 81, 6190 (1959).
For example: a) J. B. Brown, H. B. Henbest, and E. R. H.
Jones, J. Chem. Soc., 1950, 3634. b) F. S. Bridson-Jones, G. D.
Buckly, L. H. Cross, and A. P. Driver, J. Chem. Soc., 1951,
2999. c) S. Poh, R. Hernandez, M. Inagaki, and P. G. Jessop,
Org. Lett., 1, 583 (1999). d) G. I. Panov, K. A. Dubkov, E. V.
Starokon, and V. N. Parmon, React. Kinet. Catal. Lett., 76, 401
(2002).
General Procedure for Oxidation of Benzylic Carbon into
Carbonyl Group. To a benzene solution of Ru(tmp)(O)2 (3f,
5.5 mg, 0.006 mmol) in an autoclave, a solution of 9,10-dihy-
droanthracene (8a, 10 mg, 0.057 mmol) was added under a dini-
trogen oxide atmosphere. After the solvent amount was fixed at
8
For example: a) M. Iwamoto, J. Hirata, K. Matsukami,
ꢁ
14 mL, the reaction mixture was heated to 200 C under 10 atm
and S. Kagawa, J. Phys. Chem., 87, 903 (1983). b) E. Suzuki,
K. Nakashiro, and Y. Ono, Chem. Lett., 1988, 953. c) G. I. Panov,
G. A. Sheveleva, A. S. Kharitonov, V. N. Romannikov, and L. A.
Vostrikova, Appl. Catal., 82, 31 (1992). d) G. I. Panov, A. S.
Kharitonov, and V. I. Sobolev, Appl. Catal., 98, 1 (1993). e) L.
V. Piryutko, A. S. Kharitonov, V. I. Bukhtiyarov, and G. I. Panov,
Kinet. Catal., 38, 102 (1997). f) CHEMTECH, 27, 3 (1997).
of N2O for 20 h. The desired anthraquinone (9a) was purified
by silica gel column chromatography (CH2Cl2, 90% yield).
General Procedure for Dehydrogenative Aromatization Us-
ing Dinitrogen Oxide. To a benzene solution of Ru(tmp)(O)2
(3f, 6.4 mg, 0.007 mmol) in an autoclave, a solution of 9,10-dihy-
droanthracene (8a, 25.1 mg, 0.137 mmol) was added under a di-
nitrogen oxide atmosphere. After the solvent amount was fixed
at 14 mL, sulfuric acid (14.2 mg, 0.137 mmol) was added. The re-
action mixture was heated to 120 ꢁC under 10 atm of N2O for 4 h.
The desired anthracene (10a) was purified by silica gel column
chromatography (Hexane:Et2O 20:1, 99% yield).
Determination of the Amount of Nitrogen Gas Generated in
the N2O Epoxidation. The quantitative analysis of nitrogen gas
was performed with a GC attached to a Porapak Type Q column
and a TCD detector. As the internal standard, carbon dioxide
was adopted to obtain a calibration curve for N2 vs CO2. Into a
two-necked 30-mL glass flask evacuated and filled with dinitrogen
oxide, 1 mL of dinitrogen oxide and 10 mL of carbon dioxide
were injected with a gas-tight syringe. The thus obtained sample
was quantitatively analyzed by GC. Various samples containing
1–10 mL nitrogen were similarly prepared and analyzed to obtain
the calibration curve. The gas phase from the reaction vessel was
introduced to the evacuated two-necked glass flask; 10 mL of car-
bon dioxide was added as the internal standard, and the gas was
then analyzed by GC. Based on the calibration curve, 2.29 mL
of nitrogen gas was determꢁined in the 0.102 mmol scale epoxida-
tion (ideal; 2.23 mL at 21 C).
9
Recent examples: a) R. Ben-Daniel, L. Eeiner, and R.
Neumann, J. Am. Chem. Soc., 124, 8788 (2002). b) R. Ben-Daniel
and R. Neumann, Angew. Chem., Int. Ed., 42, 92 (2003).
10 a) S. G. Lias, J. E. Bartmess, J. L. Holmes, R. D. Levin,
and W. G. Mallrd, J. Phys. Chem. Ref. Data, 17, Suppl. 1
(1988). b) P. S. Drzaic, J. Marks, and J. I. Brauman, ‘‘Gas Phase
Ion Chemistry,’’ ed by M. T. Bowers, Academic Press (1984),
Vol. 3, p. 167.
11 For example: a) F. Bottomley, D. E. Paez, and P. S. White,
J. Am. Chem. Soc., 104, 5651 (1982). b) P. T. Matsunaga, J. C.
Marropoulos, and G. L. Hillhouse, Polyhedron, 14, 175 (1990).
c) G. A. Vaughan, P. B. Rupert, and G. L. Hillhouse, J. Am. Chem.
Soc., 109, 5538 (1987). d) G. A. Vaughan, G. L. Hillhouse, and
A. L. Rheingold, J. Am. Chem. Soc., 112, 7994 (1990).
12 a) T. Yamada, K. Suzuki, K. Hashimoto, and T. Ikeno,
Chem. Lett., 1999, 1043. b) A. Yamamoto, S. Kitazume, L. S.
Pu, and S. Ikeda, J. Am. Chem. Soc., 93, 371 (1971).
13 a) J. T. Groves and J. S. Roman, J. Am. Chem. Soc., 117,
5594 (1995). b) J. T. Groves and R. Quinn, J. Am. Chem. Soc.,
107, 5790 (1985).
14 J. T. Groves, K. Shalyaev, and J. Lee, ‘‘Oxometallopor-
phyrins in Oxidative Catalysis,’’ in ‘‘Porphyrin Hand Book,’’ ed
by K. M. Kadish, K. M. Smith, and R. Guilard, Academic Press,
New York (2000), Vol. 4, pp. 17–40.
References
1 Molecule of the year 1992: E. Culotta and D. E. Koshland,
Jr., Science, 258, 1862 (1992).
15 a) G. A. Tolstikov, U. M. Dzhemilev, and V. P. Yurev,
J. Org. Chem. U.S.S.R., 8, 2253 (1972). b) P. Brougham, M. S.
Cooper, D. A. Cummerson, H. Heaney, and N. Thompson, Synthe-
sis, 1987, 1015. c) J.-C. Marchon and R. Ramasseul, Synthesis,
1989, 389. d) M. Taveres, R. Ramasseul, J.-C. Marchon, B.
Bachet, C. Brassy, and J.-P. Mornon, J. Chem. Soc., Perkin Trans.
2
(1985).
3
E. I. Eager, II, ‘‘Nitrous Oxide/N2O,’’ Elsevier, New York
For example: a) W. C. Trogler, J. Chem. Educ., 72, 973
(1995). b) J. Fluckiger, A. Dallenbach, T. Blunier, B. Stauffer,

1914 Bull. Chem. Soc. Jpn., 77, No. 10 (2004)
Nitrous Oxide Oxidation
2, 1992, 1321.
Heterocycles, 40, 867 (1995).
16 It was reported that Ru(tmp)(O)2 (3f) is the most efficient
catalyst for the aerobic epoxidation because the dimerization to
the inactive ꢃ-oxo complex is suppressed.13b
17 The reaction in fluorobenzene generally gave better yields
than benzene for the other substrates.
23 S. Banfi, A. Maiocchi, A. Moggi, F. Montanari, and S.
Quici, J. Chem. Soc., Chem. Commun., 1990, 1794.
24 E. J. Corey and A. Venkateswarlu, J. Am. Chem. Soc., 94,
6190 (1972).
25 K. C. Bass, Org. Synth., Coll. Vol., V, 398 (1973).
26 T. Yamada, K. Imagawa, and T. Mukaiyama, Chem. Lett.,
1992, 2109.
18 J. T. Groves, K.-H. Ahn, and R. Quinn, J. Am. Chem. Soc.,
110, 4217 (1988).
19 The production of Ru(tmp)(CO) during the epoxidation
with molecular oxygen was reported; B. Scharbert, E. Zeisberger,
and E. Paulus, J. Organomet. Chem., 143, 493 (1995).
20 D. R. Boyd, N. D. Sharma, D. J. Stevenson, J. Chima, D. J.
Gray, and H. Dalton, Tetrahedron Lett., 31, 3887 (1991).
21 K. Imagawa, T. Nagata, T. Yamada, and T. Mukaiyama,
Chem. Lett., 1994, 527.
27 M. Linskeseder and E. Zbiral, Liebigs Ann. Chem., 1978,
1076.
28 J. A. R. Salvador, M. L. Saemelo, and A. S. Camposneves,
Tetrahedron Lett., 37, 687 (1996).
29 D. E. Over, M. Barded, J.-C. Marchon, and R. Ramasseul,
Magn. Reson. Chem., 33, 224 (1995).
30 T. Takai, K. Hata, T. Yamada, and T. Mukaiyama, Bull.
Chem. Soc. Jpn., 64, 2513 (1991).
22 a) H. Ohtake, T. Higuchi, and M. Hirobe, J. Am. Chem.
Soc., 114, 10660 (1992). b) H. Ohtake, T. Higuchi, and M. Hirobe,