A simple method for epoxidation of olefins using sodium chlorite as an oxidant without a catalyst

Article abstract of DOI:10.1021/jo0511400

Sodium chlorite has been demonstrated to be capable of epoxidizing a variety of olefins at 55-65 °C (oil bath). Chlorine dioxide is believed to be the pivotal epoxidizing agent in the reaction on the basis of the mechanistic studies.

Full text of DOI:10.1021/jo0511400

A Simple Method for Epoxidation of
Olefins Using Sodium Chlorite as an
Oxidant without a Catalyst
ment of redox active tungsten-containing-polyoxometa-
late-catalyzed reactions with hydrogen peroxide as the
oxidant. Meanwhile, several interesting small-organic-
4
molecule-catalyzed5 epoxidation reactions have been
developed, with ketone- and amine-catalyzed reactions
being typical examples. On the other hand, a more
traditional and still currently used way to synthesize
racemic epoxides is the treatment of olefins with a
stoichiometric amount of peracids without the involve-
ment of a catalyst, with m-chloroperbenzoic acid being
Xue-Li Geng, Zhi Wang, Xiao-Qiang Li, and Chi Zhang*
The State Key Laboratory of Elemento-Organic Chemistry,
The Research Institute of Elemento-Organic Chemistry,
College of Chemistry, Nankai University, Tianjin 300071,
P. R. China
6
the most often used oxidant. This catalyst-free epoxi-
zhangchi@nankai.edu.cn
Received June 7, 2005
dation reaction possesses advantages with respect to its
being simple, environmentally benign, and easily handled.
2
Sodium chlorite (NaClO ), a very cheap oxidizing
agent, has been extensively used in water treatment and
as a bleaching agent in the paper, pulp, and textiles
7
industries. However, in the field of synthetic organic
chemistry, applications of sodium chlorite are not that
broad. The most impressive use of sodium chlorite is its
efficient oxidation of aldehydes to the corresponding
8
Sodium chlorite has been demonstrated to be capable of
epoxidizing a variety of olefins at 55-65 °C (oil bath).
Chlorine dioxide is believed to be the pivotal epoxidizing
agent in the reaction on the basis of the mechanistic studies.
carboxylic acids in acidic aqueous media. More recently,
there is increasing attention focused on its utilization in
organic syntheses, including the oxidation of sulfides to
9
the corresponding sulfoxides, the chlorination of acti-
vated arenes10 and ketones with manganese complexes
11
Epoxidation of olefins is a key transformation in
organic synthesis, because epoxides are widely utilized
(
q) Nakajima, M.; Sasaki, Y.; Iwamoto, H.; Hashimoto, S.-i. Tetrahe-
1
dron Lett. 1998, 39, 87-88. (r) Coperet, C.; Adolfsson, H.; Sharpless,
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catalyst, see the following: (s) Dubois, G.; Murphy, A.; Stack, T. D. P.
Org. Lett. 2003, 5, 2469-2472.
in the laboratory as versatile building blocks and to
2
manufacture different chemicals. Nowadays, the devel-
opment of nonasymmetric epoxidation methods to provide
racemic epoxides is still important for both laboratory
and industrial use. A number of nonasymmetric metal-
catalyzed epoxidation reactions have been discovered in
(4) (a) Zuwei, X.; Ning, Z.; Yu, S.; Kunlan, L. Science 2001, 292,
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1
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(
5) For an excellent review, see the following: (a) Armstrong, A.
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1
3
the past decade; especially noteworthy was the develop-
995, 60, 3887-3889. (c) Yang, D.; Jiao, G.-S.; Yip, Y.-C.; Wong, M.-
K. J. Org. Chem. 1999, 64, 1635-1639. (d) Frohn, M.; Wang, Z.-X.;
Shi, Y. J. Org. Chem. 1998, 63, 6425-6426. (e) Hashimoto, N.; Kanda,
A. Org. Process Res. Dev. 2002, 6, 405-406. (f) Denmark, S. E.; Forbes,
D. C.; Hays, D. S.; DePue, J. S.; Wilde, R. G. J. Org. Chem. 1995, 60,
1391-1407. For amines as catalysts, see the following: (g) Ho, C.-Y.;
Chen, Y.-C.; Wong, M.-K.; Yang, D. J. Org. Chem. 2005, 70, 898-906.
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2000, 122, 8317-8318. (i) Adamo, M. F. A.; Aggarwal, V. K.; Sage, M.
A. J. Am. Chem. Soc. 2002, 124, 11223. For KBr as catalyst, see the
following: (j) Klawonn, M.; Bhor, S.; Mehltretter, G.; D o¨ bler, C.;
Fischer, C.; Beller, M. Adv. Synth. Catal. 2003, 345, 389-392.
(6) (a) Prilezhaev, N. Ber. 1909, 42, 4811. (b) Swern, D. Chem. Rev.
1949, 45, 1-68.
(7) (a) Leddy, J. J. In Riegel’s Handbook of Industrial Chemistry,
8th ed.; Kent, J. A., Ed.; Van Nostrand Reinhold Company Inc: New
York, 1983; pp 212-235. (b) Taylor, M. C.; White, J. F.; Vincent, G.
P.; Cunningham, G. L. Ind. Eng. Chem. 1940, 32, 899-903. (c) White,
J. F.; Taylor, M. C.; Vincent, G. P. Ind. Eng. Chem. 1942, 34, 782-
792. (d) F a´ bi a´ n, I. Coord. Chem. Rev. 2001, 216-217, 449-472.
(8) For sulfamic acid or resorcinol as chlorine scavenger, see the
following: (a) Lindgren, B. O.; Nilsson, T. Acta Chem. Scand. 1973,
27, 888-890. For 2-methyl-2-butene as chlorine scavenger, see the
following: (b) Kraus, G. A.; Taschner, M. J. J. Org. Chem. 1980, 45,
1175-1176. For hydrogen peroxide or DMSO as chlorine scavenger,
see the following: (c) Dalcanale, E.; Montanari, F. J. Org. Chem. 1986,
51, 567-569. For an excellent review, see the following: (d) Raach,
A.; Reiser, O. J. Prakt. Chem. 2000, 342, 605-608.
*
Corresponding author. Fax: (+86)-22-23499247. Tel: (+86)-22-
3499204.
1) Rao, A. S. In Comprehensive Organic Synthesis; Trost, B. M.,
Fleming, I., Ley, S. V., Eds.; Pergamon: Oxford, 1991; Vol. 7, pp 357-
36.
2
(
4
(
2) Gerhartz, W.; Yamamoto, Y. S.; Kaudy, L.; Rounsaville, J. F. In
Ullmann’s Encyclopedia of Industrial Chemistry, 5th ed.; Schulz, G.,
Ed.; Verlag Chemie: Weinheim, Germany, 1987; Vol. A9, pp 531-564.
(
3) For tungsten-based compounds as catalysts, see the following:
(
a) Sato, K.; Aoki, M.; Ogawa, M.; Hashimoto, T.; Noyori, R. J. Org.
Chem. 1996, 61, 8310-8311. (b) Sato, K.; Aoki, M.; Ogawa, M.;
Hashimoto, T.; Panyella, D.; Noyori, R. Bull. Chem. Soc. Jpn. 1997,
7
0, 905. (c) Duncan, D. C.; Chambers, R. C.; Hecht, E.; Hill, C. L. J.
Am. Chem. Soc. 1995, 117, 681-691. (d) Hoegaerts, D.; Sels, B. F.; de
Vos, D. E.; Verpoort, F.; Jacobs, P. A. Catal. Today 2000, 60, 209-
2
1
18. (e) Venturello, C.; Daloisio, R. J. Org. Chem. 1988, 53, 1553-
557. For a nickel-based complex as catalyst, see the following: (f)
Ben-Daniel, R.; Khenkin, A. M.; Neumann, R. Chem.sEur. J. 2000,
6
, 3722-3728. For a combination of molybdenum- or tungsten-based
heteropoly acids as catalyst, see the following: (g) Ishii, Y.; Yamawaki,
K.; Ura, T.; Yamada, H.; Yoshida, T.; Ogawa, M. J. Org. Chem. 1988,
5
3, 3587-3593. For manganese-containing compounds as catalysts,
see the following: (h) Bosing, M.; Noh, A.; Loose, I.; Krebs, B. J. Am.
Chem. Soc. 1998, 120, 7252-7259. (i) Neumann, R.; Gara, M. J. Am.
Chem. Soc. 1995, 117, 5066-5074. (j) Neumann, R.; Gara, M. J. Am.
Chem. Soc. 1994, 116, 5509-5510. (k) Lane, B. S.; Vogt, M.; DeRose,
V. J.; Burgess, K. J. Am. Chem. Soc. 2002, 124, 11946-11954. (l) Tong,
K.-H.; Wong, K.-Y.; Chan, T. H. Org. Lett. 2003, 5, 3423-3425. (m)
Murphy, A.; Pace, A.; Stack, T. D. P. J. Am. Chem. Soc. 2004, 126,
(9) (a) Hirano, M.; Yakabe, S.; Clark, J. H.; Morimoto, T. J. Chem.
Soc., Perkin Trans. 1 1996, 2693-2697. (b) Hirano, M.; Yakabe, S.;
Clark, J. H.; Kudo, H.; Morimoto, T. Synth. Commun. 1996, 26, 1875-
1886.
3
119-3122. (n) Murphy, A.; Dubois, G.; Stack, T. D. P. J. Am. Chem.
Soc. 2003, 125, 5250-5251. For rhenium-based compounds as cata-
lysts, see the following: (o) Rudolph, J.; Reddy, K. L.; Chiang, J. P.;
Sharpless, K. B. J. Am. Chem. Soc. 1997, 119, 6189-6190. (p) Yudin,
A. K.; Sharpless, K. B. J. Am. Chem. Soc. 1997, 119, 11536-11537.
(10) (a) Hirano, M.; Yakabe, S.; Monobe, H.; Morimoto, T. Can. J.
Chem. 1997, 75, 1905-1912. (b) Hirano, M.; Yakabe, S.; Monobe, H.;
Clark, J. H.; Morimoto, T. J. Chem. Soc., Perkin Trans. 1 1997, 3081-
3085.
10.1021/jo0511400 CCC: $30.25 © 2005 American Chemical Society
9610
J. Org. Chem. 2005, 70, 9610-9613
Published on Web 10/08/2005

as catalysts in the presence of alumina, the oxidation of
saturated hydrocarbons using manganese porphyrin as
SCHEME 1. Optimal Epoxidation System of
trans-Stilbene
1
2
a catalyst, the oxidation of primary alcohols to the
corresponding carboxylic acids catalyzed by TEMPO and
13
sodium hypochlorite, the dihydroxylation of olefins with
osmium as a catalyst,14 and the transformation of 3,4-
disubstituted furans into γ-hydroxybutenolides in acidic
aqueous alcohol.15 To the best of our knowledge, the use
of sodium chlorite to epoxidize olefins to the correspond-
ing epoxides in synthetic useful yields has never been
reported before. Herein, we report a simple and easy
protocol for the epoxidation of olefins that employs
sodium chlorite as the oxidant in the homogeneous
solvent mixture of acetonitrile and water at 55-65 °C
TABLE 1. Epoxidation of Olefins by Sodium Chloritea
time
(h)
epoxide yield
conversion
(%)
b
entry
olefin
(%)
c
1
2
trans-stilbene (1)
cis-stilbene (2)
trans-â-methylstyrene (3) 14 70
cis-â-methylstyrene (4)
citral (5)
triphenylethylene (6)
trans-R-methylstilbene (7) 21 70
citronellyl acetate (8)
1-phenylcyclohexene (9)
14 100
100
80
95
d
23 78 (trans/cis ) 7.5/1)
e
c
3
e
f
4
17 52 (trans/cis ) 10/1)
53
15 92
66
5
6
7
8
9
5
100
100
99
100
100
93
(oil bath).
g
Initially, the epoxidation of trans-stilbene was exam-
15 65
ined using sodium chlorite (2 equiv) in the homogeneous
solvent mixture of acetonitrile and water16 (4/1, v/v) at
room temperature. It was encouraging to observe the
formation of trans-stilbene oxide in 81% yield, though the
reaction was very slow (72 h). When the reaction tem-
perature was elevated from room temperature to 55-65
h
5
5
81
61
i
10 indene (10)
1
1
1
1
2
3
cyclooctene (11)
chalcone (12)
R-methylstyrene (13)
30 38
48 55
17 50
24 77
95
58
94
100
100
j
k
l
14 styrene (14)
1
m
5
cinnamyl alcohol (15)
6 51
1
7
°
C, the reaction was completed within 24 h, and
a Unless otherwise indicated, the reaction was conducted with
1 mmol of olefin and 3 mmol of sodium chlorite in 12 mL of distilled
afforded the epoxide in 84% yield. Further increasing the
amount of sodium chlorite to 3 equiv resulted in a
complete reaction within 14 h, and furnished the quan-
titative yield of trans-stilbene oxide.
-
4
acetonitrile and 3 mL of Na2‚EDTA aqueous solution (5 × 10
M) at 55-65 °C. Isolated yield. trans-Epoxide only. d Deter-
b
c
e
mined by GC. Benzaldehyde was detected as a side product in
f
1
g
low yield (5-10%). Determined by H NMR. cis-R-Methylstil-
A solvent-screening study was conducted using 1-phe-
bene oxide was obtained in 15% yield. h One equivalent of sodium
i
nylcyclohexene as the test substrate. Water was checked
chlorite was used. Two equivalents of sodium chlorite was used.
j
k
alone, and no reaction was observed.18 Among screened
Four equivalents of sodium chlorite was used. Benzophenone
l
was produced in 15% yield. Five millimoles of styrene was used.
Benzaldehyde was observed as a side product in 8% yield.
solvent systems, acetonitrile-water was the solvent
system of choice, in which an 81% yield of 1-phenylcy-
clohexene oxide was obtained after 5 h. DMF, DME,
DMSO, and 1,4-dioxane afforded worse results compared
to those for acetonitrile, giving the 1-phenylcyclohexene
oxide in 54%, 50%, 38%, and 40% yield, respectively.
Other solvents, including t-BuOH, THF, and acetone,
were poor choices that yielded no or trace amounts of the
desired epoxide. A dichloromethane-water system gave
no reaction at all.
Consequently, the optimal reaction system was com-
posed of 3 equiv of sodium chlorite and a solvent mixture
of acetonitrile and water (4/1, v/v), with the oil bath
temperature ranging from 55 to 65 °C (Scheme 1).
m
Cinnamic aldehyde was obtained in 16% yield.
A variety of olefins (1-15), including 1,2-disubstituted
olefins, trisubstituted olefins, cyclic olefins, one electron-
deficient olefin, one 1,1-disubstituted olefin, one mono-
substituted aromatic olefin, and an allylic alcohol, were
tested using this new epoxidation method. It was found
that epoxidation of trans-olefins (trans-stilbene and trans-
â-methylstyrene) gave the corresponding trans-epoxides
(Table 1, entries 1 and 3) exclusively, whereas cis-olefins
(cis-stilbene and cis-â-methylstyrene) yielded trans-ep-
oxides as the major product (entries 2 and 4). The
nonstereospecificity of this reaction implied that the
reaction proceeded stepwise. Moreover, it was disclosed
that electron-rich olefins gave a faster epoxidation reac-
tion, suggesting that the reaction was electrophilic. cis-
Stilbene reacted slower than trans-stilbene because the
electron density of the double bond of cis-stilbene is lower
than that of trans-stilbene.19 In the molecule of citral
(entry 5), one trisubstituted 6,7-double bond was exclu-
sively epoxidized because of its relatively greater electron
density than that of another trisubstituted 2,3-double
(
11) Yakabe, S.; Hirano, M.; Morimoto, T. Synth. Commun. 1998,
2
8, 131-138.
(
12) (a) Collman, J. P.; Tanaka, H.; Hembre, R. T.; Brauman, J. I.
J. Am. Chem. Soc. 1990, 112, 3689-3690. (b) Slaughter, L. M.;
Collman, J. P.; Eberspacher, T. A.; Brauman, J. I. Inorg. Chem. 2004,
4
3, 5198-5204.
(
13) Zhao, M.; Li, J.; Mano, E.; Song, Z.; Tschaen, D. M.; Grabowski,
E. J. J.; Reider, P. J. J. Org. Chem. 1999, 64, 2564-2566.
(
14) Junttila, M. H.; Hormi, O. E. O. J. Org. Chem. 2004, 69, 4816-
4
820.
(
15) Clive, D. L. J.; Minaruzzaman, Ou. L. J. Org. Chem. 2005, 70,
3
318-3320.
(16) Na
2
‚EDTA was used to remove the trace amount of metal ions
‚EDTA
20
bond, to give the product 16 in 53% yield.
in the reaction system. The concentration of aqueous Na
2
-4
Trisubstituted olefins were generally good substrates
Table 1, entries 5-9). In the case of trans-R-methylstil-
solution was 5 × 10 M.
(
17) When the epoxidation of trans-stilbene was carried out using
sodium chlorite (3 equiv) in 12 mL of CH CN and 3 mL of H O at 35-
5 °C (oil bath) for 14 h, only a 15% yield of trans-stilbene oxide was
obtained.
18) We also investigated the epoxidation of trans-stilbene (1 mmol)
using sodium chlorite (3 equiv) and Aliquat 336 (20 mol %) in 10 mL
(
3
2
4
(
19) Yang, D.; Zhang, C.; Wang, X.-C. J. Am. Chem. Soc. 2000, 122,
039-4043.
20) The structure of 16:
(
4
(
-4
of aqueous Na
2
‚EDTA solution (2.5 × 10 M) at 55-65 °C for 12 h.
An excellent yield (91%) of trans-stilbene oxide was obtained. Chalcone
also gave 71% yield of the desired epoxide. However, the big problem
with this system is its very limited substrate scope.
J. Org. Chem, Vol. 70, No. 23, 2005 9611

SCHEME 2. Epoxidation of cis-Stilbene by
Authentic Chlorine Dioxide Generated in Situ
bene, the desired epoxide was produced in 70% yield
21
(entry 7) along with cis-R-methylstilbene oxide 17,
obtained in 15% yield. Another trisubstituted aliphatic
olefin 8 was epoxidized in 65% yield (entry 8). Cyclic 1,2-
disubstituted olefin, indene, yielded the epoxide in 61%
yield, using 2 equiv of sodium chlorite (entry 10). As for
the electron-deficient olefin, chalcone was epoxidized in
5
(
5% yield, using 4 equiv of sodium chlorite after 2 days
entry 12). Epoxidation of styrene proceeded smoothly to
afford styrene oxide in 77% yield (entry 14). However,
-dodecene was completely inert under standard condi-
FIGURE 1. (A) UV spectrum of NaClO
2
(3 mmol) in CH
3
CN/
H
2
O (12 mL/3 mL) after being heated for 10 h at 55-65 °C.
1
(
B) UV spectrum of ClO
2
from the reaction mixture of NaClO
2
tions. As an allylic olefin, the epoxidation of cinnamyl
alcohol readily provided the desired epoxide in 51% yield
25
(
3 mmol) and (CH CO) O (3 mmol) in CH
3
2
3
CN/H
2
O (12 mL/3
mL) at room temperature.
(entry 15).
A large-scale epoxidation reaction of styrene (50 mmol)
was performed to give styrene oxide in 75% yield under
standard conditions after 2 days.
The mechanism of this new epoxidation reaction is
worth considering. cis-Stilbene (1 mmol) remained un-
rine dioxide, a reasonably disproportionate product of
sodium chlorite when heated and an inherent radical
species itself, was quite possibly the key epoxidizing
agent in our reaction. To make a convincing conclusion,
we performed the epoxidation of cis-stilbene with au-
thentic chlorine dioxide that was generated by mixing
3 2
changed after being heated in CH CN/H O (12 mL/3 mL)
25
at 55-65 °C for 24 h, and this proved thermal stability
of cis-stilbene ensured that trans-stilbene oxide, a major
product from the epoxidation of cis-stilbene under stan-
dard conditions (Table 1, entry 2), was not derived from
the reaction pathway as follows: cis-stilbene f trans-
stilbene f trans-stilbene oxide. The nonstereospecificity
of our epoxidation reaction implied that the reaction
might go on via free radical species. This was the case
because the addition of a radical-trapping compound, 2,6-
di-tert-butyl-4-methylphenol (1 equiv), in the epoxidation
of trans-stilbene resulted in a significant decrease of the
epoxide yield, to only 33%, compared to the quantitative
yield attained under standard conditions (Table 1, entry
sodium chlorite and acetic anhydride (Scheme 2). It was
observed that trans-stilbene oxide was formed as the
major epoxidation product, and that the ratio of trans-
to cis-epoxide was 9/1. On the other hand, in the course
of epoxidation of cis-stilbene under our standard condi-
tions, except that sodium chlorite was replaced with
sodium hypochlorite26 as the oxidant after 48 h, it was
found that cis-stilbene gave trans-stilbene oxide as the
major product, but the ratio of trans- to cis-epoxide was
35/1, which was quite different from the ratio (7.5/1,
Table 1, entry 2) observed in the chlorite epoxidation
system. Upon comparison of the trans- to cis-epoxide ratio
numbers in these three reactions, it was apparent that
chlorine dioxide was more likely to be the pivotal epoxi-
dizing agent in our epoxidation reaction.
2
2
1
).
It was reported that chlorine dioxide (ClO
2
) and hy-
pochlorite were generally formed during the oxidation of
an aldehyde to the corresponding acid by sodium
To detect the presence of chlorine dioxide in our
reaction, an ultraviolet-visible spectrometry experiment
was carried out. The mixture of sodium chlorite (3 mmol)
in acetonitrile (12 mL) and water (3 mL) was heated for
10 h at 55-65 °C, and the resulting cooled yellow solution
was measured by a UV spectrometer. The characteristic
8a,c
chlorite. During the investigation of bleaching proper-
ties of chlorine dioxide (ClO ), two papers mentioned that
chlorine dioxide could epoxidize styrene and trans-
2
23
24
stilbene to their corresponding epoxides in 26% and 36%
yield, respectively. This observation suggested that chlo-
2
7
absorption peak of chlorine dioxide (λmax ) 359 nm)
appeared (Figure 1), indicating that chlorine dioxide was
present in our reaction and therefore responsible for
epoxidation reaction.
(21) The structure of 17:
In conclusion, a simple epoxidation of olefins using
sodium chlorite as an oxidant without the aid of a catalyst
has been developed. The new reactivity disclosed here
expands the synthetic application of sodium chlorite to
include one that is readily available and very cheap.
(
22) The epoxidation of trans-stilbene was carried out under condi-
tions identical to those of Scheme 1 except for the addition of 15 mol
%
TEMPO. The reaction was affected dramatically, as trans-stilbene
oxide was obtained in only 16% yield at 47% conversion of the starting
material after 16 h, further indicating that a radical species was
involved in our epoxidation reaction.
(
23) Kolar, J. J.; Lindgren, B. O. Acta Chem. Scand. B 1982, 36,
(25) Masschelein, W. Ind. Eng. Chem. Res. 1967, 6, 137-142.
5
8
99-605.
3
(26) Sodium chlorate (NaClO ) gave no reaction at all in the
(
24) Lindgren, B. O.; Nilsson, T. Acta Chem. Scand. B 1974, 28,
epoxidation of tans-stilbene under the standard conditions.
(27) Kieffer, R. G.; Gordon, G. Inorg. Chem. 1968, 7, 235-239.
47-852.
9612 J. Org. Chem., Vol. 70, No. 23, 2005

Mechanistic studies show that chlorine dioxide is the key
epoxidizing agent in the reaction.
Epoxidation of Triphenylethylene. The epoxidation of
triphenylethylene (256 mg, 1 mmol) was carried out following
the typical procedure, with a reaction time of 15 h. The crude
product was purified by preparative TLC plate (2% EtOAc in
petroleum ether), which gave 2,2,3-triphenyloxirane (6P, 250
Experimental Section
1
mg, 92% yield, ref: SI1) as a white solid: mp 75-76 °C; H NMR
General Epoxidation Procedure. To a stirred mixture of
olefin (1 mmol) in the homogeneous solvent mixture of distilled
3
(300 MHz, CDCl ) δ 7.37-7.25 (m, 5H), 7.21 (m, 5H), 7.16-7.14
1
3
(m, 3H), 7.05-7.03 (m, 2H), 4.33 (s, 1H); C NMR (75 MHz,
CDCl ) δ 140.95, 135.76, 135.39, 129.15, 128.33, 127.81, 127.75,
127.68, 127.61, 127.52, 126.72, 126.30, 68.62, 68.00;28 IR (KBr)
CH
3
CN (12 mL) and aqueous Na
2
‚EDTA solution (3 mL, 5 ×
3
-
4
1
0
M) was added sodium chlorite (340 mg, 3 mmol) at room
-
1
+
temperature. The reaction flask was then put into an oil bath
with a temperature between 55 and 65 °C. The reaction was
allowed to run at 55-65 °C (oil bath), and was monitored by
TLC. The mixture turned from colorless to yellow in the course
of the reaction. After completion, the reaction was quenched by
3027, 1605, 1460, 1394, 1280, 756, 690 cm ; EI-MS (m/z) (M )
272 (20), 271 (26), 243 (16), 166 (40), 165 (100), 105 (32).
Epoxidation of Chalcone. The epoxidation of chalcone (208
mg, 1 mmol) was carried out following the typical procedure,
with a reaction time of 48 h. The crude product was purified by
flash column chromatography (5% EtOAc in petroleum ether)
a saturated aqueous solution of Na
then extracted with CH Cl three times. The combined organic
layer was washed with water and brine one time each, dried
over anhydrous Na SO , filtered, and concentrated. The products
2 2 3
S O , and the mixture was
on silica gel to give chalcone oxide (12P, ref: SI5, 123 mg, 55%)
2
2
1
as a white solid: mp 81-82 °C; H NMR (300 MHz, CDCl
3
) δ
8.02-7.99 (dd, J ) 8.4 Hz, 2H), 7.61-7.38 (m, 8H), 4.30 (d, J )
2
4
1
13
2.1 Hz, 1H), 4.07 (d, J ) 1.8 Hz, 1H); 13C NMR (75 MHz, CDCl )
were confirmed by comparison of H NMR and C NMR data
with those reported in the literature.
3
δ 193.09, 135.51, 134.03, 129.10, 128.92, 128.87, 128.81, 128.38,
29
1
25.84, 61.03, 59.41; IR (KBr) 1685, 1449, 1405, 1235, 756, 694
Epoxidation of trans-Stilbene. To a stirred mixture of
trans-stilbene (180 mg, 1 mmol) in the homogeneous solvent
-
1
+
cm ; EI-MS (m/z) (M ) 224 (83), 223 (70), 196 (16), 167 (28),
1
18 (20), 105 (100), 77 (81).
mixture of distilled CH
3
CN (12 mL) and aqueous Na
2
‚EDTA
solution (3 mL, 5 × 10 M) was added sodium chlorite (340 mg,
mmol) at room temperature. The reaction flask was then put
-4
Acknowledgment. This work was supported by
3
into an oil bath with a temperature between 55 and 65 °C (oil
bath). The reaction was monitored by TLC. The mixture turned
from colorless to yellow in the course of the reaction. After
completion within 14 h, the reaction was quenched by a
Nankai University and The State Key Laboratory of
Elemento-Organic Chemistry. We thank Prof. Jin Qu
and Prof. Qi-Lin Zhou for helpful discussions.
saturated aqueous solution of Na
then extracted with CH Cl three times. The combined organic
layer was washed with water and brine one time each, dried
2 2 3
S O , and the mixture was
Supporting Information Available: General informa-
tion, specific examples of epoxidation, NMR spectra of ep-
oxides, and analytic data of compound 17. This material is
available free of charge via the Internet at http://pubs.acs.org.
2
2
2 4
over anhydrous Na SO , filtered, and concentrated. The residue
was purified by flash column chromatography (2% EtOAc in
petroleum ether) on silica gel to give trans-stilbene oxide (1P,
JO0511400
1
ref: SI1; 196 mg, 100%) as a white solid: mp 66-67 °C; H NMR
1
3
(
300 MHz, CDCl
3
) δ 7.36 (m, 10H), 3.83 (s, 2H); C NMR (75
(
28) Yang, D.; Wong, M.-K.; Yip, Y.-C.; Wang, X.-C.; Tang, M.-W.;
28
MHz, CDCl
3
) δ 137.07, 128.48, 128.23, 125.44, 62.70; IR (KBr)
452, 1278, 860, 837, 745, 690 cm ; EI-MS (m/z) (M ) 197 (26),
96 (12), 180 (16), 167 (100), 165 (70), 105 (40), 77 (36).
Zheng, J.-H.; Cheung, K.-K. J. Am. Chem. Soc. 1998, 120, 5943-5952.
(29) Matsunaga, S.; Kinoshita, T.; Okada, S.; Harada, S.; Shibasaki,
M. J. Am. Chem. Soc. 2004, 126, 7559-7570.
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1
+
1
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J. Org. Chem, Vol. 70, No. 23, 2005 9613