Catalyst-free approach for solvent-dependent selective oxidation of organic sulfides with oxone

Article abstract of DOI:10.1039/c2gc00027j

Selective oxidation of sulfides was successfully performed by employing oxone (2KHSO₅·KHSO₄·K₂SO ₄) as oxidant without utilization of any catalyst/additive under mild reaction conditions. Notably, the reaction can be controlled by the chosen solvent. When ethanol was used as the solvent, sulfoxides were obtained in excellent yield; the reaction almost exclusively gave the sulfone in water. Furthermore, this protocol worked well for various sulfides to the corresponding sulfoxides in ethanol or sulfones in water.

Full text of DOI:10.1039/c2gc00027j

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PAPER
Catalyst-free approach for solvent-dependent selective oxidation of organic
sulfides with oxone†
Bing Yu, An-Hua Liu, Liang-Nian He,* Bin Li, Zhen-Feng Diao and Yu-Nong Li
Received 7th January 2012, Accepted 24th January 2012
DOI: 10.1039/c2gc00027j
Selective oxidation of sulfides was successfully performed by employing oxone
(2KHSO5·KHSO4·K2SO4) as oxidant without utilization of any catalyst/additive under mild reaction
conditions. Notably, the reaction can be controlled by the chosen solvent. When ethanol was used as the
solvent, sulfoxides were obtained in excellent yield; the reaction almost exclusively gave the sulfone in
water. Furthermore, this protocol worked well for various sulfides to the corresponding sulfoxides in
ethanol or sulfones in water.
cyanuric acid under biphasic conditions.23 1,3,5-Triazo-2,4,6-tri-
phosphorine-2,2,4,4,6,6-hexachloride could be also successfully
Introduction
As part of “green” concept,1 toxic organic solvents are expected
to be replaced by alternative non-toxic media and catalyst-free
utilized as a promoter for oxidation of sulfides with H2O2 as
oxidant.24 Very recently, Shi and Wei’s group25 immobilized per-
processes could be appealing. Sulfoxides and sulfones, as impor-
oxotungstates onto silica modified with multilayer ionic liquid
tant synthetic reagents, have been widely used in the preparation
of biologically and pharmaceutically significant compounds.2
Sulfoxides have also emerged as oxotransfer reagents in oxi-
dation processes3 and as ligands in asymmetric catalysis.2b In
particular, chiral sulfoxides have been extensively applied in
asymmetric synthesis.4 In this context, much effort has been
directed toward the preparation of sulfoxides and sulfones. One
of the most favored and straightforward synthetic methods could
be selective oxidation of sulfides to sulfoxides or sulfones,5
respectively, as shown in Scheme 1. Numerous types of oxidants
such as molecular oxygen,6 hydrogen peroxide,7 organic hydro-
peroxide,8 hypervalent iodine9 and other halogen derivatives10
have been used for the oxidation of sulfides to date. However,
there are some drawbacks in terms of safety, toxicity and abolish-
ment of heavy metals. It is also worth mentioning that a tran-
sition metal catalyst, such as Mn,11 Os,12 Sc,13 Ti,14 V, 15 Re,16
Ru,17 Cr,18 W, 19 Cu,20 Fe,21 is required to perform the reaction
smoothly in the most cases.
Nevertheless, only a few procedures are suitable for switch-
able synthesis of sulfoxide or sulfone via the oxidation reaction
of sulfides with the same oxidant by adjusting a reaction par-
ameter. Hussain et al. reported the selective oxidation of sulfides
to sulfoxides and sulfones with a borax–H2O2 system by varying
the pH value of the reaction mixture.22 Fukuda and co-workers
converted various sulfides to the corresponding sulfoxides and
sulfones using aqueous NaOCl in the presence of 10 mol% of
brushes to promote the oxidation reaction with H2O2 as oxidant,
affording sulfoxides and sulfones. However, a catalyst or promo-
ter was still required in those processes. Therefore, simple, con-
venient and environmentally benign methods for switchable
oxidation of sulfides to sulfoxides or to sulfones are still highly
desired.
Oxone (2KHSO5·KHSO4·K2SO4), a commercially available
salt from Caro’s acid (H2SO5), is a white, granular, free-flowing
solid peroxygen that provides powerful non-chlorine oxidation in
a stable, easy-to-handle manner. Furthermore, the byproducts
associated with oxone are generally recognized as safe. Cur-
rently, oxone has found many applications26 in oxidation of
amines,27 alcohols,28 aldehydes29 and ketones,30 epoxidation
reactions of the alkenes,31 Baeyer–Villiger reaction32 and C–H
bond oxidation processes33 due to good stability and high
efficiency. In particular, oxone can also be applied to sulfoxida-
tion reactions to form the sulfoxide as major product in aqueous
acetone or methanol.34 Moreover, Kropp et al.35 reported a sul-
foxidation method by employing inorganic-supported oxone
such as silica gel, alumina. Recently, modified oxone, e.g. ben-
zyltriphenylphosphonium peroxymonosulfate, was successfully
developed for selective oxidation of aromatic and aliphatic
sulfides under nonaqueous and aprotic conditions, which was
reported by Hajipour and co-workers.36
State Key Laboratory and Institute of Elemento-Organic Chemistry,
Nankai University, Tianjin 300071, People’s Republic of China. E-mail:
heln@nankai.edu.cn; Fax: +86 22 2350 1493; Tel: +86 22 2350 1493
†Electronic supplementary information (ESI) available: Characterization
data and copies of the NMR spectra. See DOI: 10.1039/c2gc00027j
Scheme 1 Catalytic oxidation of sulfides.
Green Chem., 2012, 14, 957–962 | 957
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Table 1 Solvent effect on oxidation of sulfides with oxonea
Table 2 Optimization of the reaction conditions in ethanola
Yieldc
(%)
Entry
1a : oxoneb
T (°C)
Time (h)
Conv.c (%)
2a
3a
1
2
3
4
1 : 0.55
1 : 0.55
1 : 0.55
1 : 0.55
1 : 0.60
1 : 1
25
60
100
60
60
60
60
60
0.5
0.5
0.5
12
12
2
9
5
0
<1
4
2
9
2
89
>99
Yieldb (%)
51
55
90
>99
94
98
>99
44
48
85
89
90
7
Entry
Solvent
Conv.b (%)
Sulfoxide (2a)
Sulfone (3a)
5
6
1
2
3
4
5
6
7
8
Toluene
1,4-Dioxane
Ethyl acetate
Acetone
PC
EC
DME
DCE
CH3COOH
DMF
CH3OH
CH3CN
C2H5OH
H2O
C2H5OH
C2H5OH
C2H5OH
3
<1
24
3
5
36
7
<1
<1
<1
<1
2
<1
2
<1
40
28
15
4
6
57
4
1
1
7d
8d
1 : 1
1 : 1.5
2
12
32
12
8
0
a Reaction conditions: to a glass tube equipped with a magnetic stir bar,
thioanisole (24.8 mg, 0.2 mmol), indicated amount of oxone, ethanol
(1 mL) as solvent were added, and the mixture was stirred for desired
time at reaction temperature. b Molar ratio. c Determined by GC with
area normalization. d Water (1 mL) as solvent.
40
10
27
13
>99
92
>99
73
94
65
82
57
36
23
9
9
59
60
82
65
86
4
76
44
29
10
11
12
13
14
15c
16c,d
17c,e
sulfone compound, i.e. phenylmethyl sulfone 3a, rather than
sulfoxide 2a as major product under the identical reaction con-
ditions (entry 14). In other words, solvent could have a remark-
able influence on the reaction outcome, particularly on the
selectivity toward sulfoxide 2a or sulfone 3a. Further investi-
gation reveals the amount of ethanol could also affect the oxi-
dation result (entries 15–17), presumably being ascribed to
variation of oxone dissolution and the concentration of the reac-
tant and reagent originating from changing solvent amount. As a
consequence, ethanol and water were employed for further inves-
tigation to highly selective formation of the sulfoxides or the
sulfone by just switching the solvent.
a Reaction conditions: To a glass tube equipped with a magnetic stir bar,
thioanisole (24.8 mg, 0.2 mmol), oxone (92.2 mg, 0.15 mmol), solvent
(1 mL) were added, and the mixture was stirred for 0.5 h at 85 °C. PC =
propylene carbonate, EC
=
ethylene carbonate, DME
=
dimethoxyethane, DCE = 1,2-dichloroethane. b Determined by GC with
area normalization. c Oxone (67.6 mg, 0.11 mmol). d Solvent (0.5 mL).
e Solvent (1.5 mL).
As a part of our continuous interest on selective oxidation
reactions,37 we herein would like to report the selective oxidation
of sulfides using ethanol or water as a solvent to afford the corre-
sponding sulfoxides or sulfones, respectively, with good yields.
This procedure needs no additional catalysts and the reaction
proceeds highly selectively in most cases.
Influence of oxidant amounts and temperature
The effect of the reaction parameters was examined by perform-
ing the reaction in ethanol, as listed in Table 2. The reaction
almost did not occur at 25 °C, while the selectivity would
become poor as further rising the temperature to 100 °C (entries
1 and 3). Therefore, the optimized temperature was proved to be
60 °C, at which moderate conversion and excellent selectivity
were achieved (entry 2). On the other hand, the conversion could
reach 90% by prolonging the reaction time to 12 h and could
further attain >99% with near 90% yield of the sulfoxide 2a by
increasing the amount of oxidant (entries 4 and 5). Very interest-
ingly, the sulfone 3a was obtained in high yield in the presence
of 1 equivalent of oxone when water was employed as solvent
(entry 7). Finally, the reaction exclusively gave the sulfone 3a
with quantitative yield by prolonging reaction time and increas-
ing the oxone amount (entry 8 vs. 7).
Results and discussion
Influence of different solvents
The exploratory experiments started using thioanisole 1a as the
model substrate. Thus, we have studied the solvent effect, and
the results are shown in Table 1. After much experimentation on
optimizing solvent, it was found that the use of a less-polar
solvent like toluene and 1,4-dioxane afforded phenyl methyl
sulfoxide 2a in low yields (Table 1, entries 1 and 2). Other
aprotic solvents such as ethyl acetate, acetone, propylene carbon-
ate, ethylene carbonate, dimethoxyethane, and 1,2-dichloro-
ethane were demonstrated to be inefficient (entries 3–8). High
polar DMF and protic solvents like methanol and acetic acid
gave good conversions but low selectivity (entries 9–11). Inter-
estingly, the reaction in acetonitrile showed a good reactivity
with excellent selectivity toward sulfoxide 2a (entry 12), similar
to Hajipour et al.’s report.36 Excellent conversion and selectivity
were achieved in ethanol (entry 13). Surprisingly, strong proton
donating solvent, e.g. water, worked well but afforded the
Substrate scope
With these results at hand, we next examined how to control this
reaction to selectively form different products. The reaction was
performed with various sulfides 1a–i to explore the generality of
the sulfoxide formation through ethanol-controlled oxidation of
the sulfide. As listed in Table 3, typical sulfides, such as thioani-
sole 1a and p-tolylmethyl sulfide 1b gave the corresponding
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Table 3 Ethanol controlled oxidation of sulfides to sulfoxidesa
Table 4 Water-switchable oxidation of sulfides to sulfonesa
Entry Substrate
1
Sulfone
Conv.b (%) Yieldc (%)
Entry Substrate
1
Sulfoxides
Conv.b (%) Yieldc (%)
>99
97
96
96
98
88
86
90
2
3
>99
>99
95
94
2
3
4
5
>99
>99
95
97
4
95
95
98
48
82
85
84
30
5
6d
7d
>99
97
94
95
6
7d
8
99
94
8
9
97
85
80
e
9
—
93
88
e
e
—
e
10
—
10
—
83
a Reaction conditions: sulfide (1 mmol), oxone (0.9221 g, 1.5 mmol),
water (5 mL) as solvent at 60 °C for 12 h. b Determined by GC with
area normalization. c Isolated yield. d SDS (27.2 mg, 10 mol%) was
added. e GC is not suitable for analyzing the compounds with too high
or too low boiling point.
a Reaction conditions: sulfide (1 mmol), oxone (0.3689 g, 0.6 mmol),
ethanol (5 mL) as solvent at 60 °C for 12 h. b Determined by GC with
area normalization. c Isolated yield. d 40 h. e GC is not suitable for
analyzing the compounds with too high or too low boiling point.
(SDS, 10 mol%) as a surfactant is needed to perform the reaction
smoothly (entries 6 and 7), probably due to the poor solubility of
1f and 1g in H2O. Moreover, the dialkyl sulfides 1h and 1i
worked perfect giving the sulfone 3h and 3i in 94% and 93%
yield, respectively (entries 8 and 9). Methylsulfanyl benzothia-
zole 1j also showed good activity to furnish the sulfone product,
i.e. 2-methanesulfonylbenzothiazole 3j, in good yield (entry 10).
In addition, the sulfone product could be easily separated from
the reaction mixture. It is also worth mentioning that the sulfox-
ide 2a can further be oxidized with 1 equivalent of oxone to the
sulfone 3a in 99% yield using water as a solvent for a shorter
time (2 h).
sulfoxides in good yields (entries 1 and 2). Various substituents
including –OCH3, –Cl and –CN could be tolerated and the sulf-
oxides were obtained in almost excellent yields (entries 3–5).
With diphenyl sulfide 1f, which is generally hard to oxidize,23
the isolated yield of 2f reached 84% (entry 6). However, just a
low yield (30%) can be obtained with dibenzothiophene sulfox-
ide 1g even the reaction time was prolonged to 40 h (entry 7).
Furthermore, the present protocol could be also applicable to
the dialkyl sulfides (entries 8 and 9). In the case of methylsulfa-
nyl benzothiazole 1j, sulfoxidation did not proceed on the 2-pos-
ition sulfur atom, while the oxidative cleavage of C–S bond took
place to afford 2-hydroxybenzothiazole 2j (entry 10).
On the other hand, we further examined the utility of prep-
aration of the sulfone via water-switched oxidation of the sulfide
with oxone as an oxidant. As shown in Table 4 substrates 1a–e
were oxidized to afford the corresponding sulfones 3a–e in
almost quantitative yields (entries 1–5). Namely, this protocol
can also tolerate several functional groups such as methoxy,
chloro, CN. In the case of 1f and 1g, sodium dodecyl sulfate
Proposed mechanism
Although the exact reason for the solvent effect is not known, it
can be assumed that solubility of oxone and hydrogen bonding
formation between oxone and the solvent would be two impor-
tant factors to control this kind oxone oxidation reaction. To gain
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a
Table 5 Oxidation of sulfide conducted by K2S2O8
Conclusions
In conclusion, a protocol for the solvent-controlled oxidative sul-
foxidation has been developed with high conversion as well as
tunable chemo-selectivity. The noteworthy feature could be that
the selective oxidation to the sulfoxide or sulfone can be
achieved by changing the solvent and using an inexpensive
reagent under safe and mild conditions without any additional
reagent. Additionally, the sulfone product could be easily separ-
ated from the reaction mixture.
Yieldb (%)
Entry
Solvent
Conv.b (%)
2a
3a
1
2
EtOH
H2O
7
82
6
76
<1
5
a Reaction conditions: to a glass tube equipped with a magnetic stir bar,
thioanisole (49.6 mg, 0.4 mmol), K2S2O8 (0.2163 g, 0.8 mmol), KHSO4
(54.5 mg, 0.4 mmol), K2SO4 (69.7 mg, 0.4 mmol), solvent (2 mL) were
added, and the mixture was stirred for 12 h at 60 °C. b Determined by
GC with area normalization.
Experimental section
General information
The starting materials were commercially available and were
used without further purification except solvents. The products
were isolated by column chromatography on silica gel
(200–300 mesh) using petroleum ether (60–90 °C) and ethyl
acetate. NMR spectra were determined on Bruker 400 in CDCl3.
1H NMR chemical shifts were referenced to residual solvent as
determined relative to CDCl3 (7.26 ppm). The 13C NMR chemi-
cal shifts were reported in ppm relative to the carbon resonance
of CDCl3 (central peak is 77.0 ppm). 1H NMR peaks are labelled
as singlet (s), doublet (d), triplet (t), and multiplet (m). The
coupling constants, J, are reported in hertz (Hz). GC-MS data
were performed on Finnigan HP G1800 A. GC analyses were
performed on a Shimadzu GC-2014 equipped with a capillary
column (RTX-wax 30 m × 0.25 μm and RTX-17 30 m ×
0.25 μm) using a flame ionization detector. 2-(Methylthio)ben-
zothiazole 1j was prepared according to previous literature
report.41
Scheme 2 Proposed reaction pathway for the water-promoted oxi-
dation of sulfide.
a deeper insight into the solvent effect, the 1a oxidation with
potassium persulfate (K2S2O8) was carried out in a protic
solvent such as ethanol, water under the same reaction conditions
as the oxidation with oxone (Table 5).
Ethanol was found to be inactive, possible due to the solubi-
lity problem of K2S2O8, whereas water gave good yield of the
sulfoxide.
General procedure for the selective oxidation of sulfides to
sulfoxides
To a 25 mL glass tube, sulfide (1.0 mmol), oxone (0.3689 g,
0.6 mmol), ethanol (5.0 mL) were added and the mixture was
stirred at 60 °C for 12 h. The mixture was cooled to room temp-
erature and added with water (10 mL), then extracted by ethyl
acetate (25 mL × 4). After drying with anhydrous Na2SO4, the
organic residue was analyzed by GC and then purified by
column chromatography on silica gel (200–300 mesh) with ethyl
acetate/petroleum ether to afford the desired product.
The water effect could be attributed not only to the improved
solubility but also to possible generation of both an intramolecu-
lar hydrogen bond within the oxone molecule38 and an inter-
molecular hydrogen bond between H2O and oxone,39 leading to
formation of the 5-membered ring fused with 6-membered ring
as shown in Scheme 2. Therefore, the presence of such hydrogen
bonds could allow facile oxygen transfer from the peroxy
oxygen of oxone to the sulfide and subsequent to sulfoxide, thus
resulting in promotion of the oxidation to formation of the
sulfone as the main product (Tables 1 and 4). On the other hand,
in the case of ethanol as solvent, ready formation of intramolecu-
lar hydrogen bond with the oxone molecule rather than typical
intermolecular H-bonding in such a fashion as depicted in
Scheme 2, could account for the preferred production of the sulf-
oxide. When a mixture of ethanol and water was used as a
solvent under standard conditions, the product distribution com-
prising the sulfoxide and the sulfone was dependent on the
volume ratio of EtOH/H2O.40 All the experiments in this study
could support such hypothesis about dependence of the product
distribution on hydrogen bond formation.
General procedure for the oxidation of sulfides to sulfones
To a 25 mL glass tube, sulfide (1.0 mmol), oxone (0.9221 g,
1.5 mmol), water (5.0 mL) were added and the mixture was
stirred at 60 °C for 12 h. The mixture was then cooled to room
temperature and extracted by ethyl acetate (25 mL × 4). After
drying with anhydrous Na2SO4 overnight, the liquid was ana-
lyzed by GC. The residue was concentrated under reduced
pressure to afford the desired product without further purification
except 3j. All compounds were characterized by H NMR, 13C
1
NMR and mass spectroscopy, which are consistent with those
reported in the literature.7,43,44
960 | Green Chem., 2012, 14, 957–962
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(t, J = 7.4 Hz, 6H). 13C NMR (100 MHz, CDCl3) δ (ppm): 54.1,
16.2, 13.3. EI-MS, m/z (%): 135.06 (20) [M+].
Characterization data for substrate 1j, the oxidation products
2a–j and 3a–j
2-(Methylthio)benzothiazole (1j).42 The product was obtained
as a white solid (3.553 g, 98% yield). 1H NMR (400 MHz,
CDCl3) δ (ppm): 7.87 (d, J = 8.1 Hz, 1H), 7.75 (d, J = 8.0 Hz,
1H), 7.41 (t, J = 7.6 Hz, 1H), 7.29 (t, J = 7.5 Hz, 1H), 2.79 (s,
3H). 13C NMR (100 MHz, CDCl3) δ (ppm): 168.1, 153.3,
135.1, 126.0, 124.1, 121.3, 120.9, 15.9. EI-MS, m/z (%): 182.08
(100) [M+].
Dimethyl sulfoxide (2i).46 The product was obtained as a col-
1
orless liquid (0.063 g, 80% yield). H NMR (400 MHz, CDCl3)
δ (ppm): 2.50 (s, 6H). 13C NMR (100 MHz, CDCl3) δ (ppm):
40.8. EI-MS, m/z (%): 78.00 (50) [M+].
2-Benzothiazolone (2j).47 The product was obtained as a
white solid (0.125 g, 83% yield). 1H NMR (400 MHz, CDCl3) δ
(ppm): 10.60 (s, 1H), 7.39 (d, J = 7.8 Hz, 1H), 7.29–7.25 (m,
1H), 7.20–7.12 (m, 2H). 13C NMR (100 MHz, CDCl3) δ (ppm):
173.6, 135.5, 126.5, 123.8, 123.2, 122.4, 111.9. EI-MS, m/z (%):
151.06 (100) [M+].
Phenylmethyl sulfoxide (2a).9a The product was obtained as a
colorless liquid (0.123 g, 88% yield). 1H NMR (400 MHz,
CDCl3) δ (ppm): 7.62–7.60 (m, 2H), 7.51–7.44 (m, 3H), 2.68
(s, 3H). 13C NMR (100 MHz, CDCl3) δ (ppm): 145.6, 130.9,
129.2, 123.4, 43.8. EI-MS, m/z (%): 140.00 (79) [M+].
Phenylmethyl sulfone (3a).23 The product was obtained as a
white solid (0.152 g, 97% yield). 1H NMR (400 MHz, CDCl3) δ
(ppm): 7.92 (d, J = 7.5 Hz, 2H), 7.66–7.54 (m, 3H), 3.04 (s,
3H). 13C NMR (100 MHz, CDCl3) δ (ppm): 140.4, 133.6,
129.3, 127.2, 44.4. EI-MS, m/z (%): 156.01 (25) [M+].
p-Tolylmethyl sulfoxide (2b).7c The product was obtained as a
1
pale yellow liquid (0.133 g, 86% yield). H NMR (400 MHz,
CDCl3) δ (ppm): 7.50 (d, J = 8.0 Hz, 2H), 7.29 (d, J = 8.0 Hz,
2H), 2.66 (s, 3H), 2.37 (s, 3H). 13C NMR (100 MHz, CDCl3) δ
(ppm): 142.3, 141.4, 129.9, 123.4, 43.8, 21.2. EI-MS, m/z (%):
153.99 (30) [M+].
p-Tolylmethyl sulfone (3b).7c The product was obtained as a
white solid (0.162 g, 95% yield). 1H NMR (400 MHz, CDCl3) δ
(ppm): 7.82 (d, J = 8.0 Hz, 2H), 7.36 (d, J = 7.9 Hz, 2H), 3.03
(s, 3H), 2.45 (s, 3H). 13C NMR (100 MHz, CDCl3) δ (ppm):
144.7, 137.7, 129.9, 127.4, 44.6, 21.6. EI-MS, m/z (%): 170.03
(51) [M+].
4-Methoxyphenylmethyl sulfoxide (2c).7c The product was
1
obtained as a pale yellow solid (0.153 g, 90% yield). H NMR
(400 MHz, CDCl3) δ (ppm): 7.70–7.52 (m, 2H), 7.03–7.01 (m,
2H), 3.84 (s, 3H), 2.69 (s, 3H). 13C NMR (100 MHz, CDCl3) δ
(ppm): 161.9, 136.4, 125.4, 114.8, 55.5, 43.9. EI-MS, m/z (%):
170.00 (19) [M+].
4-Methoxyphenylmethyl sulfone (3c).7c The product was
obtained as a white solid (0.175 g, 94% yield). 1H NMR
(400 MHz, CDCl3) δ (ppm): 7.87 (d, J = 8.7 Hz, 2H), 7.02 (d, J
= 8.7 Hz, 2H), 3.88 (s, 3H), 3.03 (s, 3H). 13C NMR (100 MHz,
CDCl3) δ (ppm): 163.6, 132.2, 129.5, 114.4, 55.7, 44.8. EI-MS,
m/z (%): 186.08 (91) [M+].
p-Chlorophenylmethyl sulfoxide (2d).7c The product was
1
obtained as a pale yellow solid (0.143 g, 82% yield). H NMR
(400 MHz, CDCl3) δ (ppm): 7.58 (d, J = 8.5 Hz, 2H), 7.49 (d, J
= 8.5 Hz, 2H), 2.71 (s, 3H). 13C NMR (100 MHz, CDCl3) δ
(ppm): 144.1, 137.2, 129.6, 124.9, 44.0. EI-MS, m/z (%):
175.95 (25) [M+], 174.03 (61) [M+].
p-Chlorophenylmethyl sulfone (3d). The product was obtained
as a white solid (0.181 g, 95% yield). 1H NMR (400 MHz,
CDCl3) δ (ppm): 7.91–7.88 (m, 2H), 7.58–7.54 (m, 2H), 3.06
(s, 3H). 13C NMR (100 MHz, CDCl3) δ (ppm): 140.4, 139.0,
129.7, 128.9, 44.5. EI-MS, m/z (%): 191.98 (24) [M+], 190.01
(62) [M+].
4-Cyanophenylmethyl sulfoxide (2e).43 The product was
obtained as a white solid (0.140 g, 85% yield). 1H NMR
(400 MHz, CDCl3) δ (ppm): 7.83 (d, J = 8.2 Hz, 2H), 7.77 (d, J
= 8.1 Hz, 2H), 2.76 (s, 3H). 13C NMR (100 MHz, CDCl3) δ
(ppm): 151.4, 133.0, 124.3, 117.7, 114.8, 43.8. EI-MS, m/z (%):
165.00 (88) [M+].
4-Cyanophenylmethyl sulfone (3e).48 The product was
obtained as a white solid (0.176 g, 97% yield). 1H NMR
(400 MHz, CDCl3) δ (ppm): 8.08 (d, J = 8.3 Hz, 2H), 7.89 (d, J
= 8.0 Hz, 2H), 3.09 (s, 3H). 13C NMR (100 MHz, CDCl3) δ
(ppm): 144.4, 133.2, 128.2, 117.6, 117.0, 44.2. EI-MS, m/z (%):
180.83 (9) [M+].
Diphenyl sulfoxide (2f).23 The product was obtained as a
white solid (0.170 g, 84% yield). 1H NMR (400 MHz, CDCl3) δ
(ppm): 7.66–7.64 (m, 4H), 7.49–7.42 (m, 6H). 13C NMR
(100 MHz, CDCl3) δ (ppm): 145.6, 131.0, 129.3, 124.8. EI-MS,
m/z (%): 202.01 (100) [M+].
Diphenyl sulfone (3f).23 The product was obtained as a white
solid (0.205 g, 94% yield). 1H NMR (400 MHz, CDCl3) δ
(ppm): 7.96–7.94 (m, 4H), 7.59–7.49 (m, 6H). 13C NMR
(100 MHz, CDCl3) δ (ppm): 141.6, 133.2, 129.3, 127.7. EI-MS,
m/z (%): 217.93 (20) [M+].
Dibenzothiophene sulfoxide (2g).44 The product was obtained
as a white solid (0.060 g, 30% yield). 1H NMR (400 MHz,
CDCl3) δ (ppm): 7.99 (d, J = 7.6 Hz, 2H), 7.82 (d, J = 7.7 Hz,
2H), 7.61 (t, J = 7.5 Hz, 3H), 7.51 (t, J = 7.5 Hz, 3H). 13C NMR
(100 MHz, CDCl3) δ (ppm): 145.2, 137.1, 132.5, 129.5, 127.5,
121.9. EI-MS, m/z (%): 200.05 (100) [M+].
Dibenzothiophene sulfone (3g).44 The product was obtained
as a white solid (0.205 g, 95% yield). 1H NMR (400 MHz,
CDCl3) δ (ppm): 7.83–7.78 (m, 4H), 7.66–7.62 (m, 2H),
7.55–7.51 (m, 2H). 13C NMR (100 MHz, CDCl3) δ (ppm):
137.7, 133.9, 131.6, 130.4, 122.2, 121.6. EI-MS, m/z (%):
216.00 (100) [M+].
Di(n-propyl) sulfoxide (2h).45 The product was obtained as a
colorless liquid (0.114 g, 85% yield). 1H NMR (400 MHz,
CDCl3) δ (ppm): 2.72–2.53 (m, 4H), 1.83–1.73 (m, 4H), 1.05
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Di(n-propyl) sulfone (3h).45 The product was obtained as a
white solid (0.141 g, 94% yield). 1H NMR (400 MHz, CDCl3) δ
(ppm): 2.90–2.86 (m, 4H), 1.86–1.76 (m, 4H), 1.02 (t, J = 7.4
Hz, 6H). 13C NMR (100 MHz, CDCl3) δ (ppm): 54.2, 15.6,
13.0. EI-MS, m/z (%): 151.05 (22) [M+].
19 A. Bordoloi, A. Vinu and S. B. Halligudi, Chem. Commun., 2007, 4806–
4808.
20 I. Gamba, S. Palavicini, E. Monzani and L. Casella, Chem.–Eur. J., 2009,
15, 12932–12936.
21 J. Legros and C. Bolm, Angew. Chem., Int. Ed., 2003, 42, 5487–5489.
22 S. Hussain, S. K. Bharadwaj, R. Pandey and M. K. Chaudhuri,
Eur. J. Org. Chem., 2009, 3319–3322.
23 N. Fukuda and T. Ikemoto, J. Org. Chem., 2010, 75, 4629–4631.
24 K. Bahrami, M. M. Khodaei and M. S. Arabi, J. Org. Chem., 2010, 75,
6208–6213.
25 X. Y. Shi, X. Y. Han, W. J. Ma, J. F. Wei, J. Li, Q. Zhang and Z. G. Chen,
J. Mol. Catal. A: Chem., 2011, 341, 57–62.
26 M. Eissen, M. Strudthoff, S. Backhaus, C. Eismann, G. Oetken,
S. Kaling and D. Lenoir, J. Chem. Educ., 2011, 88, 284–291.
27 (a) J. D. Fields and P. J. Kropp, J. Org. Chem., 2000, 65, 5937–5941;
(b) K. S. Webb and V. Seneviratne, Tetrahedron Lett., 1995, 36, 2377–
2378.
28 (a) C. Bolm, A. S. Magnus and J. P. Hildebrand, Org. Lett., 2000, 2,
1173–1175; (b) M. Hirano, M. Oose and T. Morimoto, Bull. Chem. Soc.
Jpn., 1991, 64, 1046–1047.
Dimethyl sulfone (3i).49 The product was obtained as a white
solid (0.088 g, 93% yield). 1H NMR (400 MHz, CDCl3) δ
(ppm): 2.97 (s, 6H). 13C NMR (100 MHz, CDCl3) δ (ppm):
42.6. EI-MS, m/z (%): 94.00 (34) [M+].
2-Methanesulfonylbenzothiazole (3j).42 The product was
obtained as a white solid (0.188 g, 88% yield). 1H NMR
(400 MHz, CDCl3) δ (ppm): 8.20 (d, J = 8.3 Hz, 1H), 8.01 (d, J
= 7.8 Hz, 1H), 7.66–7.57 (m, 2H), 3.41 (s, 3H). 13C NMR
(100 MHz, CDCl3) δ (ppm): 166.3, 152.4, 136.5, 128.1, 127.7,
125.3, 122.3, 42.4. EI-MS, m/z (%): 212.98 (72) [M+].
29 B. R. Travis, M. Sivakumar, G. O. Hollist and B. Borhan, Org. Lett.,
2003, 5, 1031–1034.
30 M. Uyanik, M. Akakura and K. Ishihara, J. Am. Chem. Soc., 2009, 131,
251–262.
Acknowledgements
31 (a) Z.-X. Wang, Y. Tu, M. Frohn, J.-R. Zhang and Y. Shi, J. Am. Chem.
Soc., 1997, 119, 11224–11235; (b) D. Yang, Acc. Chem. Res., 2004, 37,
497–505; (c) S. E. Denmark, D. C. Forbes, D. S. Hays, J. S. DePue and
R. G. Wilde, J. Org. Chem., 1995, 60, 1391–1407; (d) M. Frohn,
Z.-X. Wang and Y. Shi, J. Org. Chem., 1998, 63, 6425–6426;
(e) N. Hashimoto and A. Kanda, Org. Process Res. Dev., 2002, 6, 405–
406.
We are grateful to the National Natural Science Foundation of
China (No. 21172125), the “111” Project of Ministry of Edu-
cation of China (Project No. B06005), and the Committee of
Science and Technology of Tianjin for financial support.
32 (a) A. Chrobok, Tetrahedron, 2010, 66, 6212–6216; (b) M. E. Gonzalez-
Nunez, R. Mello, A. Olmos and G. Asensio, J. Org. Chem., 2005, 70,
10879–10882; (c) M. Renz and B. Meunier, Eur. J. Org. Chem., 1999,
1999, 737–750.
Notes and references
33 P. Liu, Y. G. Liu, E. L. M. Wong, S. Xiang and C. M. Che, Chem. Sci.,
2011, 2, 2187–2195.
34 (a) B. M. Trost and D. P. Curran, Tetrahedron Lett., 1981, 22, 1287–
1290; (b) K. S. Webb, Tetrahedron Lett., 1994, 35, 3457–3460;
(c) F. A. Davis, S. G. Lal and H. D. Durst, J. Org. Chem., 1988, 53,
5004–5007.
35 P. J. Kropp, G. W. Breton, J. D. Fields, J. C. Tung and B. R. Loomis, J.
Am. Chem. Soc., 2000, 122, 4280–4285.
36 A. R. Hajipour, S. E. Mallakpour and H. Adibi, J. Org. Chem., 2002, 67,
8666–8668.
1 (a) C.-J. Li and B. M. Trost, Proc. Natl. Acad. Sci. U. S. A., 2008, 105,
13197–13202; (b) P. Anastas and N. Eghbali, Chem. Soc. Rev., 2010, 39,
301–312.
2 (a) M. C. Carreno, Chem. Rev., 1995, 95, 1717–1760; (b) I. Fernandez
and N. Khiar, Chem. Rev., 2003, 103, 3651–3706; (c) E. Wojaczynska
and J. Wojaczynski, Chem. Rev., 2010, 110, 4303–4356; (d) K. A. Stingl
and S. B. Tsogoeva, Tetrahedron: Asymmetry, 2010, 21, 1055–1074.
3 A. M. Khenkin and R. Neumann, J. Am. Chem. Soc., 2002, 124, 4198–
4199.
4 H. Pellissier, Tetrahedron, 2006, 62, 5559–5601.
37 (a) C.-X. Miao, L.-N. He, J.-Q. Wang and J.-L. Wang, Adv. Synth. Catal.,
2009, 351, 2209–2216; (b) C.-X. Miao, J.-Q. Wang, B. Yu, W.-G. Cheng,
J. Sun, S. Chanfreau, L.-N. He and S.-J. Zhang, Chem. Commun., 2011,
47, 2697–2699; (c) J.-Q. Wang, L.-N. He and C.-X. Miao, Green Chem.,
2009, 11, 1013–1017; (d) B. Li, A.-H. Liu, L.-N. He, Z.-Z. Yang, J. Gao
and K.-H. Chen, Green Chem., 2012, 14, 130.
38 O. Ermer and C. Röbke, Helv. Chim. Acta, 2003, 86, 2908–2913.
39 (a) V. K. Aggarwal, C. Lopin and F. Sandrinelli, J. Am. Chem. Soc.,
2003, 125, 7596–7601; (b) V. K. Aggarwal and G. Y. Fang, Chem.
Commun., 2005, 3448–3450.
40 To a glass tube equipped with a magnetic stir bar, thioanisole (24.8 mg,
0.2 mmol), oxone (92.2 mg, 0.15 mmol), and solvent mixture (1 mL)
were added, and the mixture was stirred for 0.5 h at 85 °C; V(EtOH) : V
(H2O) = 0.40 : 0.60 mL, conversion: 66%, yield: 2a (10%), 3a (56%); V
(EtOH) : V(H2O) = 0.20 : 0.80 mL, conversion: 86%, yield: 2a (10%), 3a
(76%).
41 R. V. Kumar, K. V. S. R. S. Kumar and K. R. Gopal, J. Heterocycl.
Chem., 2005, 42, 153–156.
42 J. Pospisil and H. Sato, J. Org. Chem., 2011, 76, 2269–2272.
43 P. Hanson, R. A. A. J. Hendrickx and J. R. L. Smith, Org. Biomol.
Chem., 2008, 6, 745–761.
44 M. Kirihara, J. Yamamoto, T. Noguchi, A. Itou, S. Naito and Y. Hirai,
Tetrahedron, 2009, 65, 10477–10484.
45 P. Hanson, R. A. A. J. Hendrickxz and J. R. L. Smith, New J. Chem.,
2010, 34, 65–84.
5 (a) J. Legros, J. R. Dehli and C. Bolm, Adv. Synth. Catal., 2005, 347,
19–31; (b) J. E. Backvall, Modern oxidation methods, Wiley-VCH, Wein-
heim, Germany, 2010.
6 T. Chinnusamy and O. Reiser, ChemSusChem, 2010, 3, 1040–1042.
7 (a) F. Shi, M. K. Tse, H. M. Kaiser and M. Beller, Adv. Synth. Catal.,
2007, 349, 2425–2430; (b) R. Ricoux, M. Allard, R. Dubuc, C. Dupont,
J. D. Marechal and J. P. Mahy, Org. Biomol. Chem., 2009, 7, 3208–3211;
(c) C. B. Yang, H. Zhang, J. Liao, J. Zhu, J. G. Deng, Q. P. Jin and
B. Yu, Green Chem., 2009, 11, 1401–1405.
8 For a recent review, see: S. Kumar, S. Verma, S. L. Jain and B. Sain,
Tetrahedron Lett., 2011, 52, 3393–3396.
9 (a) J. N. Moorthy, K. Senapati and K. N. Parida, J. Org. Chem., 2010,
75, 8416–8421; (b) J. N. Moorthy, K. Senapati, K. N. Parida, S. Jhulki,
K. Sooraj and N. N. Nair, J. Org. Chem., 2011, 76, 9593–9601.
10 P. Kowalski, K. Mitka, K. Ossowska and Z. Kolarska, Tetrahedron, 2005,
61, 1933–1953.
11 (a) M. Hirano, S. Yakabe, J. H. Clark, H. Kudo and T. Morimoto, Synth.
Commun., 1996, 26, 1875–1886; (b) F. Voss, E. Herdtweck and T. Bach,
Chem. Commun., 2011, 47, 2137–2139.
12 B. M. Choudary, C. R. V. Reddy, B. V. Prakash, M. L. Kantam and
B. Sreedhar, Chem. Commun., 2003, 754–755.
13 M. Matteucci, G. Bhalay and M. Bradley, Org. Lett., 2003, 5, 235–238.
14 M. A. M. Capozzi, C. Centrone, G. Fracchiolla, F. Naso and
C. Cardellicchio, Eur. J. Org. Chem., 2011, 4327–4334.
15 S. L. Jain, B. S. Rana, B. Singh, A. K. Sinha, A. Bhaumik, M. Nandi and
B. Sain, Green Chem., 2010, 12, 374–377.
16 J. B. Arterburn and S. L. Nelson, J. Org. Chem., 1996, 61, 2260–2261.
17 X. T. Zhou, H. B. Ji, Z. Cheng, J. C. Xu, L. X. Pei and L. F. Wang,
Bioorg. Med. Chem. Lett., 2007, 17, 4650–4653.
46 H. E. Gottlieb, V. Kotlyar and A. Nudelman, J. Org. Chem., 1997, 62,
7512–7515.
47 T. Itoh and T. Mase, Org. Lett., 2007, 9, 3687–3689.
48 W. Zhu and D. Ma, J. Org. Chem., 2005, 70, 2696–2700.
49 R. G. Chapman and J. C. Sherman, J. Org. Chem., 2000, 65, 513–516.
18 L. Xu, J. Cheng and M. L. Trudell, J. Org. Chem., 2003, 68, 5388–5391.
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