Efficient Swern oxidation and Corey-Kim oxidation with ion-supported methyl sulfoxides and methyl sulfides

Article abstract of DOI:10.1016/j.tet.2012.06.026

The Swern oxidation of various benzylic and allylic alcohols, primary alcohols, and secondary alcohols with two ion-supported methyl sulfoxides A-1 (C₆) and B-1 (C₁₀), and oxalyl chloride in the presence of triethylamine in dichloromethane, followed by simple diethyl ether extraction of the reaction mixture, gave the corresponding aldehydes and ketones, respectively, in good yields with high purity. Similarly, the Corey-Kim oxidation of various benzylic and allylic alcohols, primary alcohols, and secondary alcohols with two ion-supported methyl sulfides A-2 (C₆) and B-2 (C₁₀), and N-chlorosuccinimide in the presence of triethylamine in dichloromethane, followed by simple diethyl ether extraction of the reaction mixture, furnished the corresponding aldehydes and ketones, respectively, in good yields with high purity. Both reactions did not produce any unpleasant odor at all. In the Swern oxidation, ion-supported methyl sulfides were recovered in high yields and could be re-oxidized to produce ion-supported methyl sulfoxides A-1 (C₆) and B-1 (C₁₀), for reuse in the same oxidation. In the Corey-Kim oxidation, ion-supported methyl sulfides A-2 (C₆) and B-2 (C₁₀) were recovered in high yields and could be also reused for the same oxidation.

Full text of DOI:10.1016/j.tet.2012.06.026

Tetrahedron 68 (2012) 6849e6855
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Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Efficient Swern oxidation and CoreyeKim oxidation with ion-supported methyl
sulfoxides and methyl sulfides
*
Daisuke Tsuchiya, Masayuki Tabata, Katsuhiko Moriyama, Hideo Togo
Graduate School of Science, Chiba University, Yayoi-cho 1-33, Inage-ku, Chiba 263-8522, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 25 May 2012
Received in revised form 5 June 2012
Accepted 7 June 2012
Available online 15 June 2012
The Swern oxidation of various benzylic and allylic alcohols, primary alcohols, and secondary alcohols
with two ion-supported methyl sulfoxides A-1 (C6) and B-1 (C10), and oxalyl chloride in the presence of
triethylamine in dichloromethane, followed by simple diethyl ether extraction of the reaction mixture,
gave the corresponding aldehydes and ketones, respectively, in good yields with high purity. Similarly,
the CoreyeKim oxidation of various benzylic and allylic alcohols, primary alcohols, and secondary al-
cohols with two ion-supported methyl sulfides A-2 (C6) and B-2 (C10), and N-chlorosuccinimide in the
presence of triethylamine in dichloromethane, followed by simple diethyl ether extraction of the reaction
mixture, furnished the corresponding aldehydes and ketones, respectively, in good yields with high
purity. Both reactions did not produce any unpleasant odor at all. In the Swern oxidation, ion-supported
methyl sulfides were recovered in high yields and could be re-oxidized to produce ion-supported methyl
sulfoxides A-1 (C6) and B-1 (C10), for reuse in the same oxidation. In the CoreyeKim oxidation, ion-
supported methyl sulfides A-2 (C6) and B-2 (C10) were recovered in high yields and could be also
reused for the same oxidation.
Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction
chromatography in the TEMPO-catalyzed oxidation with DIB is
likewise required. On the other hand, the Swern oxidation and the
Organic synthesis characterized by high efficiency, low toxicity,
minimal odor, and the production of a small amount of waste is
very important for green chemistry. Various attempts to this end
have been made.1 Of the currently available organic reactions, the
oxidation of alcohols to aldehydes or ketones is one of the most
fundamental, widespread, and important reactions in both research
laboratories and production plants. As examples of practical, less-
toxic, metal-free, and environmentally benign methods for the
oxidation of alcohols, the DesseMartin oxidation with periodinane
CoreyeKim oxidation can be carried out without such tiresome
procedures, using affordable reagents, including dimethyl sulfoxide
and oxalyl chloride, and dimethyl sulfide and NCS, respectively. The
Swern oxidation in particular is one of the most efficient and se-
lective oxidation methods for the preparation of various aldehydes
or ketones from alcohols. These features have contributed to the
extensive use of the Swern oxidation in the synthesis of natural
products and pharmaceuticals. However, dimethyl sulfide, a co-
product of the Swern oxidation, is a highly malodorous volatile
compound and it is very difficult to handle or isolate the desired
oxidation product without being exposed to the unpleasant odor.
Therefore, the CoreyeKim oxidation is not popular for organic
synthesis because it requires the use of malodorous volatile di-
methyl sulfide. As an alternative, the odorless Swern oxidation that
uses modified dimethyl sulfoxides, such as 6-(methanesulfinyl)
hexanoic acid,6 polyfluoroalkyl methyl sulfoxide,7 dodecyl methyl
sulfoxide,8 and polymer-supported methyl sulfoxide,9 was studied
for its ability to produce aldehydes and ketones in high yields.
However, there are still several drawbacks, such as the complicated
procedure for the separation of the desired product from methyl
sulfides; co-products, the use of a large amount of solvent, the
occurrence of side reactions, such as the Pummerer reaction, the
difference in reactivity from the original Swern oxidation with
(1,1,1-triacetoxy-1,1-dihydro-1,2-benziodoxol-3(1H)-one),2
the
TEMPO-catalyzed oxidation with (diacetoxy)iodobenzene (DIB),3
and the Swern oxidation with DMSO and oxalyl chloride4 are the
most popular, particularly in the synthesis of natural products,
pharmaceuticals, and agrochemicals. As a related oxidation to the
Swern oxidation, the CoreyeKim oxidation with dimethyl sulfide
and N-chlorosuccinimide (NCS)5 is just as attractive because it uses
metal-free, cheap, and easily available reagents. However, period-
inane in the DesseMartin oxidation is very expensive and highly
explosive, and therefore, careful handling is required. The removal
of iodobenzene from the reaction mixture by column
* Corresponding author. E-mail address: togo@faculty.chiba-u.jp (H. Togo).
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2012.06.026

6850
D. Tsuchiya et al. / Tetrahedron 68 (2012) 6849e6855
dimethyl sulfoxide, and the presence of a trace amount of polymer
species when polymer-supported methyl sulfoxides are used. In the
CoreyeKim oxidation, instead of malodorous volatile dimethyl
sulfide, modified reagents, such as polyfluoroalkyl methyl sulfide,7b
dodecyl methyl sulfide,8b and methyl sulfide bearing a morpholine
group,10 were developed to produce aldehydes and ketones, with-
out an unpleasant odor. However, there remain certain issues, in-
cluding the requirement of expensive reagents, the complicated
separation of the desired products from the reaction mixture, the
removal of dodecyl methyl sulfide by careful column chromatog-
raphy, and treatment of the reaction mixture with excess aq 1 N HCl
solution to remove methyl sulfide bearing a morpholine group.
Based on our previous reports of ion-supported reagents, such as
ion-supported PhI,11 ion-supported Ph3P,12 and ion-supported
DIB,13 we expected that the use of ion-supported methyl sulfox-
ide for the Swern oxidation and ion-supported methyl sulfide for
the CoreyeKim oxidation would eliminate the unpleasant odor and
enable the easy separation of the desired oxidation product
from the reaction mixture and the reuse of the ion-supported
methyl sulfoxide and the ion-supported methyl sulfide, re-
spectively. Recently, the Swern oxidation with ionic-liquid-grafted
methyl sulfoxides, such as 1-(20-methanesulfinyl)ethyl-2,3-
dimethylimidazolium triflate, 1-(30-methanesulfinyl)propyl-2,3-
dimethylimidazolium triflate, and 1-(60-methanesulfinyl)hexyl-
2,3-dimethylimidazolium triflate, with oxalyl chloride in the pres-
ence of triethylamine was reported.14 However, easily affordable
hydrogen peroxide could not be used for the preparation of those
methyl sulfoxides, and instead, periodic acid was used. The first one
was not effective for the Swern oxidation, the reactions with the
second one and the third one were limited to the oxidation of
benzylic and allylic alcohols, and secondary alcohols except pri-
mary alcohols, and the diethyl ether extracts of the reaction mix-
ture must be purified by column chromatography. As part of our
synthetic study of ion-supported reagents,11e13 we would like to
report the Swern oxidation of various benzylic and allylic alcohols,
primary alcohols, and secondary alcohols with two novel ion-
supported methyl sulfoxides A-1 (C6) and B-1 (C10), in the pres-
ence of oxalyl chloride and triethylamine,15 and the CoreyeKim
oxidation of various benzylic and allylic alcohols, primary alcohols,
and secondary alcohols with two novel ion-supported methyl sul-
fides A-2 (C6) and B-2 (C10), in the presence of NCS and triethyl-
amine, respectively.
Scheme 1. Preparation of ion-supported methyl sulfoxides C6 and C10
.
supported methyl sulfoxides A-1 (C6) and B-1 (C10) are shown in
Table 1. Various benzylic and allylic alcohols, primary alcohols, and
secondary alcohols including
b-cholestanol and D-glucose de-
rivative could be oxidized and simple diethyl ether extraction of the
reaction mixture produced the corresponding conjugated (benzylic
and allylic) aldehydes (entries 1e5, 7, and 9e14), non-conjugated
aldehydes (entries 15e20), and ketones (entries 21e32), re-
spectively, in high yields with high purity. During these reactions,
no unpleasant odor was detected at all. Overall, the reactivities of
ion-supported methyl sulfoxides A-1 (C6) and B-1 (C10) for the
present Swern oxidation were almost the same. However, the
yields of aldehydes obtained by reacting ion-supported methyl
2. Results and discussion
Ion-supported methyl sulfoxides A-1 (C6) and B-1 (C10) were
prepared from commercially available 6-chlorohexan-1-ol and 10-
bromodecan-1-ol in five steps in 62% overall yield and 61% overall
yield, respectively, as shown in Scheme 1. The introduction of
a hexa-methylene group and a deca-methylene group is important
to increase the solubility of ion-supported methyl sulfoxide in
CH2Cl2, the recovery of co-products; namely, ion-supported methyl
sulfides; A-2 (C6) and B-2 (C10), and the yields of the oxidation
products. Thus, oxalyl chloride was added dropwise to a solution of
ion-supported methyl sulfoxide A-1 (C6) or B-1 (C10) in CH2Cl2 at
ꢀ70 ꢁC and the reaction mixture was stirred for 30 min at the same
temperature. Then, a solution of alcohol in CH2Cl2 was added
dropwise to the solution at ꢀ70 ꢁC and the obtained reaction
mixture was stirred for 30 min. Triethylamine was added dropwise
at ꢀ70 ꢁC, and the entire mixture was stirred for 1 h at the same
temperature. The resulting mixture was warmed slowly to room
temperature. After 2 h, the mixture was quenched with water and
extracted with diethyl ether. After removal of diethyl ether, alde-
hyde or ketone was obtained in good yield with high purity without
any unpleasant odor at all. This is the greatest advantage of the
present reactions. The results for the Swern oxidation with ion-
sulfoxide B-1 (C10) with
b-citronellol, 3-phenyl-1-propanol, and
adamantanemethanol were higher than those obtained with ion-
supported methyl sulfoxide A-1 (C6) (entries 15e20). Another ad-
vantage presented by ion-supported methyl sulfoxide B-1 (C10) is
that it is a solid and therefore easy to use compared with ion-
supported methyl sulfoxide A-1 (C6), which is a viscous liquid. Af-
ter the oxidation, ion-supported methyl sulfides bearing a hexa-
methylene group (A-2) and a deca-methylene group (B-2), which
are the co-products of the present reaction, were recovered, re-
spectively, in w73% yield and w90% yield by chloroform extraction
of the aq solution and re-oxidized with hydrogen peroxide to form
ion-supported methyl sulfoxides A-1 (C6) and B-1 (C10) in quanti-
tative yields, respectively. Thus, both ion-supported methyl sulf-
oxides A-1 (C6) and B-1 (C10) are effective for the Swern oxidation
of various alcohols. Moreover, ion-supported methyl sulfide B-2
derived from B-1 (C10) could be recovered in high yield due to the

D. Tsuchiya et al. / Tetrahedron 68 (2012) 6849e6855
Table 1 (continued)
6851
Table 1
Swern oxidation of alcohols with Ion-supported methyl sulfoxides A-1 and B-1
Entry
Reagent
Product
Yielda
Purity
25
26
27
28
29
30
A-1
B-1
A-1
B-1
A-1
B-1
99
91
99
91
99
92
99
99
99
99
99
99
Entry
Reagent
Product
Yielda
Purity
1
2
3
4
5
A-1
B-1
A-1
B-1
A-1
92
98
84
84
99
99
98
88
96
98
31
32
A-1
B-1
88
99
99
99
6c
7
A-1
B-1
B-1
95
94
84
99
89
99
8b,c
33
A-1
B-1
74
73
96
90
34
9
A-1
B-1
A-1
B-1
A-1
B-1
A-1
B-1
A-1
B-1
A-1
B-1
A-1
B-1
A-1
B-1
93
86
99
94
99
92
83
89
85
92
78
90
96
95
99
99
99
99
99
94
98
93
82
99
85
99
90
99
99
99
99
99
a
Isolated Yield.
b
Ion-supported methyl sulfoxide (3.0 equiv), (COCl)2 (2.9 equiv), and Et3N
10
11
12
13
14
15
16
17
18
19b
20b
21
22
23
24
(9.0 equiv) were used.
c
Ion-supported methyl sulfoxide that was recovered and regenerated, was used.
presence of a hydrophobic long alkyl chain. Once ion-supported
methyl sulfoxides A-1 (C6) and B-1 (C10) were obtained, they
could be reused for the same Swern oxidation to generate the
corresponding aldehydes in good yields with high purity again, by
simple diethyl ether extraction of the reaction mixture (entries 6
and 8).
Then, the CoreyeKim oxidation of alcohols was carried out. A
solution of ion-supported methyl sulfide A-2 (C6) or B-2 (C10) and
alcohol in CH2Cl2 was added to a CH2Cl2 solution of NCS at ꢀ40 ꢁC,
and the obtained mixture was stirred for 0.5 h. Triethylamine was
added to the mixture at ꢀ40 ꢁC, and the mixture was stirred for
14 h. The reaction mixture was quenched with water and extracted
with diethyl ether. After the removal of diethyl ether, aldehyde or
ketone was obtained in good yield with high purity without any
unpleasant odor at all again. The results with ion-supported methyl
sulfides A-2 (C6) and B-2 (C10) are shown in Table 2, and indicate
that the oxidation of various benzylic and allylic alcohols, primary
alcohols, and secondary alcohols, followed by diethyl ether ex-
traction of the reaction mixture, furnished the corresponding
conjugated aldehydes (entries 1e12), non-conjugated aldehydes
(entries 13e18), and ketones (entries 19e27, 29, 31, and 32), re-
spectively, in high yields with high purity. Overall, the yields of
products obtained with ion-supported methyl sulfide A-2 (C6) are
slightly higher than those obtained with ion-supported methyl
sulfide B-2 (C10). Fortunately, both ion-supported methyl sulfides
A-2 (C6) and B-2 (C10) are solids and therefore easy to operate. After
the oxidation reaction with ion-supported methyl sulfides A-2 (C6)
and B-2 (C10), ion-supported methyl sulfides A-2 (C6) and B-2 (C10
)
were recovered by chloroform extraction of the aq solutions in
w84% yield and w90% yield, respectively. Once ion-supported
methyl sulfides A-2 (C6) and B-2 (C10) were recovered, they could
be reused for the same CoreyeKim oxidation to generate the

6852
D. Tsuchiya et al. / Tetrahedron 68 (2012) 6849e6855
Table 2 (continued)
Table 2
CoreyeKim oxidation of alcohols with Ion-supported methyl sulfides A-2 and B-2
Entry
Method
Product
Yielda
Purity
23b
24
A-2
B-2
A-2
B-2
A-2
99
83
99
88
99
99
99
98
99
99
Entry
Method
Product
Yielda
Purity
25b
26
1
A-2
B-2
A-2
B-2
A-2
B-2
A-2
B-2
A-2
B-2
A-2
B-2
A-2
B-2
A-2
B-2
A-2
B-2
A-2
B-2
A-2
B-2
97
83
85
81
93
81
89
88
82
74
94
75
80
90
94
92
92
87
86
86
85
78
99
84
96
95
97
94
96
99
94
99
96
78
99
80
97
91
98
99
86
99
99
99
2
27b
3b
4
28b,c
29
A-2
B-2
B-2
90
85
84
99
99
97
30c
31b
A-2
B-2
88
90
99
99
5
32b
6
a
Isolated yield.
b
c
Reaction was carried out at ꢀ20 ꢁC.
7
Ion-supported methyl sulfide that was recovered, was reused.
8
corresponding ketone in good yields with high purity again, by
simple diethyl ether extraction of the reaction mixture (entries 28
and 30).
9
10
11
12
13b
14
15b
16
17
18b
19b
20b
21b
22b
3. Conclusion
An efficient and odorless Swern oxidation of various benzylic
and allylic alcohols, as well as primary and secondary alcohols in-
cluding b-cholestanol and D-glucose derivative with ion-supported
methyl sulfoxides A-1 (C6) and B-1 (C10), followed by simple diethyl
ether extraction, was carried out to provide the corresponding al-
dehydes and ketones in high yields with high purity, without the
production of any unpleasant odor. The isolation of aldehydes or
ketones from the reaction mixture was simply carried out by
diethyl ether extraction of the reaction mixture. Moreover, ion-
supported methyl sulfides A-2 (C6) and B-2 (C10) were recovered
in good yields and re-oxidized to form ion-supported methyl sulf-
oxides A-1 (C6) and B-1 (C10) for reuse in the same reaction. We
believe that the presence of 2-methyl group of 1-(30-meth-
anesulfinyl)propyl-2,3-dimethylimidazolium triflate and 1-(60-
methanesulfinyl)hexyl-2,3-dimethylimidazolium triflate14 is not
good in the presence of base for the Swern oxidation due to the
abstraction of the proton from the 2-methyl group of them. Simi-
larly, an efficient and odorless CoreyeKim oxidation of various
benzylic and allylic alcohols, as well as primary and secondary al-
cohols with ion-supported methyl sulfides A-2 (C6) and B-2 (C10),
followed by simple diethyl ether extraction, was carried out to
provide the corresponding aldehydes and ketones in high yields
with high purity, without the production of any unpleasant odor.
The isolation of aldehydes or ketones from the reaction mixture
was again simply carried out by diethyl ether extraction of the re-
action mixture. Therefore, we believe that ion-supported methyl
sulfoxides A-1 (C6) and B-1 (C10) for the Swern oxidation, and ion-
supported methyl sulfides A-2 (C6) and B-2 (C10) for the CoreyeKim
oxidation will become useful and environmentally benign reagents
in organic synthesis.

D. Tsuchiya et al. / Tetrahedron 68 (2012) 6849e6855
6853
4. Experimental section
4.1. General
J¼6.7 Hz, 2H); 13C NMR (100 MHz, CDCl3):
d
¼15.51, 25.70, 28.79,
29.15, 29.19, 29.37, 29.41, 29.50, 32.76, 34.28, 63.00.
4.4. Preparation of 6-(methylthio)hexan-1-yl p-
toluenesulfonate
1H NMR and 13C NMR spectra were obtained with JEOL-JNM-
ECX400, JEOL-JNM-ECS400, and JEOL-JNM-ECA500 spectrometers.
Chemical shifts are expressed in parts per million downfield from
p-TsCl (72 mmol) in CH2Cl2 (60 mL) was added to a CH2Cl2
(60 mL) solution of 6-(methylthio)hexan-1-ol (60 mmol), Et3N
(90 mmol), and Me3N$HCl (6.0 mmol) at 0 ꢁC, and the obtained
mixture was stirred for 1 h. Then, H2O (100 mL) was added to the
reaction mixture, which was neutralized with 1 M HCl and was
extracted with EtOAc (200 mLꢂ2). The combined organic layer was
washed with water, brine, dried over Na2SO4, and concentrated in
vacuo. The residue was purified by column chromatography on
silica gel (hexane/EtOAc¼4:1, Rf¼0.4) to give 6-(methylthio)hexan-
1-yl p-toluenesulfonate in 95% yield. 10-(Methylthio)decan-1-yl p-
toluenesulfonate was prepared in 90% yield by the same procedure
under the same conditions.
TMS in
d units. Mass spectra were recorded on JMS-T100GCV, JMS-
HX110, and Thermo LTQ Orbitrap spectrometers. IR spectra were
measured with a JASCO FT/IR-4100 spectrometer. Melting points
were determined with a Yamato Melting Point Apparatus Model
MP-21. Silica gel 60 (Kanto Kagaku Co.) was used for column
chromatography.
4.2. Preparation of 6-mercaptohexan-1-ol
Thiourea (270 mmol) and KI (90 mmol) were added to an EtOH
(150 mL) solution of 6-chlorohexan-1-ol (180 mmol) at room
temperature, and the mixture was refluxed for 14 h. Then, aq NaOH
(2.7 M, 270 mmol, 100 mL) was added to the mixture, which was
then refluxed for 3 h. The reaction mixture was cooled to room
temperature, and it was neutralized with aq HCl (1 M, 200 mL).
Then, the mixture was extracted with Et2O (300 mLꢂ2). The
combined organic layer was dried over Na2SO4, filtered, and
evaporated in vacuo. The residue was dissolved in Et2O (200 mL)
and the mixture was filtered. The filtrate was concentrated to give
6-mercaptohexan-1-ol. 10-Mercaptodecan-1-ol was prepared by
the same procedure under the same conditions.
4.4.1. 6-(Methylthio)hexan-1-yl p-toluenesulfonate. Colorless oil; IR
(neat): 1175, 1360 cmꢀ1
;
1H NMR (400 MHz, CDCl3):
d
¼1.31e1.37
(m, 4H), 1.51e1.68 (m, 4H), 2.07 (s, 3H), 2.44 (t, J¼7.3 Hz, 2H), 2.45
(s, 3H), 4.02 (t, J¼6.5 Hz, 2H), 7.35 (d, J¼8.1 Hz, 2H), 7.79 (d, J¼8.1 Hz,
2H); 13C NMR (100 MHz, CDCl3):
28.72, 33.93, 70.41, 127.75, 129.72, 133.05, 144.60.
d
¼15.39, 21.52, 24.89, 27.92, 28.60,
4.4.2. 10-(Methylthio)decan-1-yl p-toluenesulfonate. Colorless oil;
IR (neat): 1176, 1361 cmꢀ1; 1H NMR (500 MHz, CDCl3):
d
¼1.23e1.39
(m, 12H), 1.54e1.67 (m, 4H), 2.09 (s, 3H), 2.45 (s, 3H), 2.48 (t,
J¼7.4 Hz, 2H), 4.02 (t, J¼6.6 Hz, 2H), 7.34 (d, J¼8.3 Hz, 2H), 7.79 (d,
4.2.1. 6-Mercaptohexan-1-ol. Colorless oil; IR (neat): 1054, 2555,
J¼8.3 Hz, 2H); 13C NMR (100 MHz, CDCl3):
¼15.50, 21.59, 25.27,
d
3348 cmꢀ1
;
1H NMR (400 MHz, CDCl3):
d
¼1.34e1.47 (m, 5H),
28.72, 28.75, 28.84, 29.10, 29.12, 29.25, 29.30, 34.24, 70.63, 127.82,
129.75, 133.20, 144.57.
1.54e1.67 (m, 4H), 1.84 (s, 1H), 2.54 (q, J¼7.4 Hz, 2H), 3.64 (t,
J¼6.6 Hz, 2H); 13C NMR (100 MHz, CDCl3):
¼24.49, 25.17, 28.05,
d
32.53, 33.86, 62.76.
4.5. Preparation of 3-methyl-1-[60-(methylthio)hexan-10-yl]-
1H-imidazolium p-toluenesulfonate A-2 (C6)
4.2.2. 10-Mercaptodecan-1-ol. Colorless oil. IR (neat): 1053, 2554,
3362 cmꢀ1
;
1H NMR (500 MHz, CDCl3):
d
¼1.28e1.37 (m, 14H),
1-Methylimidazole (33 mmol) was added to a CH3CN (30 mL)
1.52e1.68 (m, 4H), 2.52 (t, J¼7.3 Hz, 2H), 3.60 (t, J¼6.8 Hz, 2H); 13C
solution
of
6-(methylthio)hexan-1-yl
p-toluenesulfonate
NMR (100 MHz, CDCl3):
29.34, 32.49, 33.82, 62.53.
d
¼24.43, 25.57, 28.16, 28.85, 29.22, 29.25,
(30 mmol) at room temperature, and the mixture was stirred at
60 ꢁC for 48 h. The reaction mixture was concentrated in vacuo, and
the residue was washed with Et2O (100 mLꢂ3) to give 3-methyl-1-
[60-(methylthio)hexan-10-yl]-1H-imidazolium p-toluenesulfonate
A-2 (C6) in 99% yield. 3-Methyl-1-[100-(methylthio)decan-10-yl]-
1H-imidazolium p-toluenesulfonate B-2 (C10) was prepared in 91%
yield by the same procedure under the same conditions.
4.3. Preparation of 6-(methylthio)hexan-1-ol
CH3I (189 mmol) was added to a DMF (160 mL) solution of 6-
mercaptohexan-1-ol (180 mmol) and K2CO3 (198 mmol) at 0 ꢁC,
and the mixture was stirred for 2 h. The reaction mixture was fil-
tered, which was concentrated. Then, H2O (150 mL) was added to
the residue, which was extracted with EtOAc (200 mLꢂ3). The
combined organic layer was washed with brine, dried over Na2SO4,
filtered, and concentrated in vacuo. Purification of the residue by
distillation (85e95 ꢁC/1.0 mmHg) gave 6-(methylthio)hexan-1-ol
(66% yield from 6-chlorohexan-1-ol).
4.5.1. 3-Methyl-1-[60-(methylthio)hexan-10-yl]-1H-imidazolium p-
toluenesulfonate A-2. Mp 49e53 ꢁC; IR (neat): 1034, 1191 cmꢀ1; 1H
NMR (400 MHz, CDCl3):
d
¼1.19e1.38 (m, 4H), 1.48e1.56 (m, 2H),
1.73e1.81 (m, 2H), 2.07 (s, 3H), 2.34 (s, 3H), 2.43 (t, J¼7.3 Hz, 2H),
3.93 (s, 3H), 4.14 (t, J¼7.6 Hz, 2H), 7.15 (d, J¼7.8 Hz, 2H), 7.31 (t,
J¼1.8 Hz, 1H), 7.41 (t, J¼1.8 Hz, 1H), 7.74 (d, J¼7.8 Hz, 2H), 9.59 (s,
10-(Methylthio)decan-1-ol (110e120ꢁC/1.0 mm Hg) was pre-
pared in 78% yield by the same procedure under the same
conditions.
1H); 13C NMR (100 MHz, CDCl3):
d¼15.41, 21.20, 25.64, 27.87, 28.62,
29.95, 33.89, 36.25, 49.63, 121.81, 123.52, 125.71, 128.61, 137.51,
139.36, 143.56; HRMS (ESI) calcd for C11H21N2Sþ [Mþ]: 213.1420.
Found: 213.1414.
4.3.1. 6-(Methylthio)hexan-1-ol. Colorless oil; IR (neat): 1055,
3365 cmꢀ1
;
1H NMR (400 MHz, CDCl3):
d
¼1.34e1.47 (m, 4H),
4.5.2. 3-Methyl-1-[100-(methylthiꢁo)decan-10-yl]-1H-imidazolium p-
toluenesulfonate B-2. Mp 62e67 C; IR (Nujol): 1034, 1198 cmꢀ1; 1H
€
1.55e1.67 (m, 5H), 2.10 (s, 3H), 2.50 (t, J¼7.4 Hz, 2H), 3.64 (t,
J¼6.6 Hz, 2H); 13C NMR (100 MHz, CDCl3):
d
¼15.47, 25.32, 28.49,
NMR (400 MHz, CDCl3):
d
¼1.23e1.38 (m, 12H), 1.56 (sep, J¼7.4 Hz,
29.01, 32.57, 34.14, 62.76.
2H), 1.74 (sep, J¼7.0 Hz, 2H), 2.09 (s, 3H), 2.34 (s, 3H), 2.48 (t,
J¼7.5 Hz, 2H), 3.94 (s, 3H), 4.13 (t, J¼7.4 Hz, 2H), 7.14 (d, J¼8.0 Hz,
2H), 7.30 (t, J¼1.8 Hz, 1H), 7.45 (t, J¼1.8 Hz, 1H), 7.76 (d, J¼8.1 Hz,
4.3.2. 10-(Methylthio)decan-1-ol. Colorless oil; IR (neat): 1057,
3348 cmꢀ1 1H NMR (400 MHz, CDCl3):
¼1.29e1.39 (m, 13H),
1.53e1.63 (m, 4H), 2.10 (s, 3H), 2.49 (t, J¼7.4 Hz, 2H), 3.64 (t,
;
d
2H), 9.73 (s, 1H); 13C NMR (100 MHz, CDCl3):
d
¼15.47, 21.20, 26.09,
28.67, 28.85, 29.06, 29.08, 29.20, 29.28, 30.09, 34.20, 36.25, 49.80,

6854
D. Tsuchiya et al. / Tetrahedron 68 (2012) 6849e6855
121.76, 123.55, 125.74, 128.55, 137.75, 139.19, 143.83; HRMS (ESI)
calcd for C15H29N2Sþ [Mþ]: 269.2046. Found: 269.2039.
addition of aq satd NaHCO3 solution, ion-supported methyl sulfide
A-2 or B-2 was extracted with CHCl3 (40 mLꢂ3). The organic layer
was dried over Na2SO4 and filtered. After removal of the solvent,
the residue was washed with diethyl ether (10 mLꢂ2), and con-
centrated in vacuo to provide ion-supported methyl sulfide A-2 in
w73% yield derived from ion-supported methyl sulfoxide A-1 (C6),
and ion-supported methyl sulfide B-2 in w90% yield derived from
ion-supported methyl sulfoxide B-1 (C10), respectively. The re-
covered ion-supported methyl sulfides A-2 and B-2 were quanti-
tatively oxidized to the corresponding ion-supported methyl
sulfoxides A-1 (C6) and B-1 (C10), respectively, with hydrogen per-
oxide in MeOH, as mentioned above.
4.6. Preparation of 3-methyl-1-[60-(methanesulfinyl) hexan-
10-yl]-1H-imidazolium p-toluenesulfonate A-1 (C6)
H2O2 (30% in water, 1.47 mL, 48 mmol) was added dropwise to
a solution of 3-methyl-1-[60-(methylthio)hexan-10-yl]-1H-imida-
zolium p-toluenesulfonate; (7.69 g, 20 mmol) in MeOH (30 mL) at
0 ꢁC, and the mixture was stirred for 2 h at room temperature. The
reaction mixture was quenched with aq satd Na2SO3 solution, and
concentrated in vacuo. The obtained mixture was dissolved in
CH2Cl2, dried over Na2SO4, and filtered. After removal of the sol-
vent, ion-supported methyl sulfoxide A-1 (C6) was obtained in 99%
yield. 3-Methyl-1-[100-(methylsulfinyl)decan-10-yl]-1H-imidazo-
lium p-toluenesulfonate B-1 (C10) was prepared in 95% yield by the
same procedure under the same conditions.
4.9. General procedure for the CoreyeKim oxidation with
ion-supported methyl sulfides A-2 or B-2
A solution of ion-supported methyl sulfide A-2 (C6) (2.0 mmol,
0.769 g) and alcohols (1.0 mmol) in CH2Cl2 (6 mL) was added to
a CH2Cl2 (5 mL) solution of N-chlorosuccinimide (2.0 mmol,
0.267 g) at ꢀ40 ꢁC, and the obtained mixture was stirred for 0.5 h.
Triethylamine (5.0 mmol, 0.506 g, 0.70 mL) was added to the
mixture at ꢀ40 ꢁC, and the mixture was stirred for 14 h. The re-
action mixture was quenched with H2O (20 mL), and extracted with
diethyl ether (60 mL). The organic layer was washed by H2O
(20 mL) and a satd aq NaHCO3 (30 mLꢂ2). The organic layer was
dried over Na2SO4 and concentrated in vacuo to provide aldehyde
or ketone. The purity was estimated by 1H NMR measurements.
4.6.1. 3-Methyl-1-[60-(methanesulfinyl)hexan-10-yl]-1H-imidazolium
p-toluenesulfonate A-1. Colorless oil; IR (neat): 1034 cmꢀ1; 1H NMR
(500 MHz, CDCl3):
d
¼1.28e1.49 (m, 4H), 1.67e1.86 (m, 4H), 2.34 (s,
3H), 2.55 (s, 3H), 2.68 (t, J¼7.6 Hz, 2H), 3.93 (s, 3H), 4.19 (t, J¼7.4 Hz,
2H), 7.15 (d, J¼8.1 Hz, 2H), 7.36e7.38 (m, 2H), 7.74 (d, J¼8.1 Hz, 2H),
9.63 (s, 1H); 13C NMR (125 MHz, CDCl3):
d
¼21.21, 22.06, 25.37,
27.59, 29.59, 36.25, 38.30, 49.49, 53.79, 121.96, 123.38, 125.71,
128.64, 137.63, 139.48, 143.43; HMRS (APPI) calcd for C11H21ON2S
[Mþ]: 229.1369. Found: 229.1357.
4.6.2. 3-Methyl-1-[100-(methanesulfinyl)decan-10-yl]-1H-imidazo-
ꢀ1
ꢁ
€
lium p-toluenesulfonate B-1. Mp 63e78 C; IR (Nujol): 1034 cm
;
1H NMR (500 MHz, CDCl3):
d
¼1.24e1.50 (m, 12H), 1.72e1.80 (m,
4.10. Recovery of ion-supported methyl sulfides A-2 or B-2 in
the CoreyeKim oxidation
4H), 2.34 (s, 3H), 2.56 (s, 3H), 2.62e2.76 (m, 2H), 3.97 (s, 3H), 4.16 (t,
J¼7.4 Hz, 2H), 7.14 (d, J¼8.0 Hz, 2H), 7.25 (t, J¼1.9 Hz, 1H), 7.36 (t,
J¼1.7 Hz,1H), 7.77 (d, J¼8.1 Hz, 2H), 9.68 (s,1H); 13C NMR (100 MHz,
4.10.1. For ion-supported methyl sulfide A-2. After the above ex-
traction of aldehyde or ketone from the reaction mixture, the aq
layer was concentrated in vacuo. Then, KI (2.0 mmol, 0.332 g), AcOH
(2 mL), and TsOH$H2O (2.2 mmol, 0.379 g) were added to the res-
idue at room temperature, and the mixture was stirred for 1 h. The
reaction mixture was quenched with a satd aq Na2SO3 (5 mL) and
aq NaHCO3 (5 mL), and extracted with CHCl3 (40 mLꢂ3). The or-
ganic layer was dried over Na2SO4 and concentrated in vacuo to
give A-2, 3-methyl-1-[60-(methylthio)-hexyl]-1H-imidazolium p-
toluenesulfonate in 84% yield.
CDCl3):
d
¼21.27, 22.44, 26.03, 28.56, 28.74, 28.97, 28.97, 29.02,
30.03, 36.37, 38.50, 49.87, 54.58, 121.63, 123.38, 125.82, 128.62,
137.85, 139.36, 143.46; HRMS (ESI) calcd for C15H29N2OSþ [Mþ]:
285.1995. Found: 285.1990.
4.7. General procedure for the Swern oxidation using ion-
supported methyl sulfoxide A-1 or B-1
Oxalyl chloride (0.34 mL) was added dropwise to a solution of
ion-supported methyl sulfoxide A-1 (C6) (1.60 g, 4.0 mmol) in
CH2Cl2 (6 mL) at ꢀ70 ꢁC and the mixture was stirred for 30 min at
the same temperature. Then, a solution of alcohol (2.0 mmol) in
CH2Cl2 (3 mL) was added dropwise at ꢀ70 ꢁC and the obtained
mixture was stirred for 30 min. Triethylamine (1.66 mL, 12 mmol)
was added dropwise at ꢀ70 ꢁC and the mixture was stirred for 1 h
at the same temperature. The resulting mixture was warmed to
ꢀ60 ꢁC and stirred for 1.5 h at the same temperature. Then, the
mixture was warmed to ꢀ50 ꢁC and stirred for 1 h at the same
temperature. Finally, the mixture was warmed to room tempera-
ture and stirred for 2 h at the same temperature. The reaction
mixture was quenched with water (10 mL), neutralized (pH¼6e7)
with aq 1 M HCl solution, and extracted with diethyl ether
(40 mLꢂ2). The organic layer was washed with water (10 mL), dried
over Na2SO4, and filtered. After removal of the solvent, aldehyde or
ketone was obtained. The purity was estimated by 1H NMR
measurements.
4.10.2. For ion-supported methyl sulfide B-2. After the above ex-
traction of aldehyde or ketone from the reaction mixture, K2CO3
(0.32 g, 2.2 mmol) was added to the aq layer. The mixture was
stirred over night at room temperature. Ion-supported methyl
sulfide was extracted with CH2Cl2 (20 mLꢂ3). The organic layer was
washed with a satd aq NaCl (10 mL), dried over Na2SO4, filtered, and
concentrated in vacuo. The residue was washed with diethyl ether
(10 mLꢂ2) to provide B-2, 3-methyl-1-[100-(methylthio)decyl]-1H-
imidazolium p-toluenesulfonate in 90% yield.
Most of ketones and aldehydes in the present study are com-
mercially available and they are identified with authentic samples,
except for the following products.
4.10.3. 4-Formylbenzyl pivalate. Colorless oil; IR (neat): 1702,
1733 cmꢀ1; 1H NMR (500 MHz, CDCl3):
d
¼1.26 (s, 9H), 5.19 (s, 2H),
7.50 (d, J¼8.0 Hz, 2H), 7.89 (d, J¼8.0 Hz, 2H), 10.02 (s, 1H); 13C NMR
(100 MHz, CDCl3):
143.13, 177.93, 191.67; HMRS (APCI) calcd for C13H16O3 [MþH]:
d
¼27.03, 38.69, 65.04, 127.62, 129.83, 135.79,
4.8. General procedure for recovery of ion-supported methyl
sulfides A-2 or B-2 in the Swern oxidation
220.1094. Found: 220.1098.
After the above extraction of aldehyde or ketone from the re-
action mixture, the aq layer was concentrated in vacuo. After the
4.10.4. 1-Adamantanecarboxaldehyde. Mp: 140e142 ꢁC (lit.16 Mp:
ꢀ1
;
1H NMR (CDCl3, 400 MHz):
ꢁ
€
146e148 C); IR (Nujol): 1722 cm

D. Tsuchiya et al. / Tetrahedron 68 (2012) 6849e6855
6855
d
¼1.68e1.80 (m, 12H), 2.03e2.09 (m, 3H), 9.32 (s, 1H); 13C NMR
References and notes
(CDCl3, 100 MHz):
d
¼27.31, 35.80, 36.52, 44.82, 206.09.
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4.10.5. 4-[(tert-Butyldimethylsilyl)oxy]cyclohexanone. Colorless oil
(commercial, Oil); IR (neat): 1720 cmꢀ1; 1H NMR (400 MHz, CDCl3):
d
¼0.10 (s, 6H), 0.92 (s, 9H), 1.83e2.02 (m, 4H), 2.18e2.28 (m, 2H),
2.61e2.73 (m, 2H), 4.10e4.17 (m, 1H); 13C NMR (100 MHz, CDCl3):
d
¼ꢀ5.39, 17.53, 25.24, 33.65, 36.38, 65.39, 211.26; HMRS (APPI)
3. (a) De Mico, A.; Margarita, R.; Parlanti, L.; Vescovi, A.; Piancatelli, G. J. Org. Chem.
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calcd for C12H25O2Si [MþH]: 229.1618. Found: 229.1617.
4.10.6. 4-Methyl-N-(4-oxocyclohexyl)benzenesulfon-amide. Mp
ꢀ1
;
1H NMR (CDCl3, 400 MHz)
ꢁ
€
101e102 C; IR (Nujol) 1713 cm
1.70e1.79 (m, 2H), 2.01e2.09 (m, 2H), 2.27e2.42 (m, 4H), 2.45 (s,
d
3H), 3.54e3.62 (m,1H), 4.62 (d, J¼6.6 Hz,1H), 7.33 (d, J¼8.6 Hz, 2H),
7.79 (d, J¼8.6 Hz, 2H); 13C NMR (CDCl3, 100 MHz)
d 21.5, 32.3, 38.2,
49.8, 126.9, 129.9, 137.5, 143.7, 209.2; HRMS (ESI) calcd for
C13H16NO3S [M-Hþ] 266.0856, found 266.0859.
4.10.7. 2,3,4,6-Tetra-O-benzyl-
IR (neat): 698, 738, 1094, 1165, 1755 cmꢀ1
CDCl3):
¼3.64e3.75 (m, 2H), 3.88e3.98 (m, 2H), 4.12 (d, J¼6.1 Hz,
1H), 4.43e4.76 (m, 8H), 4.98 (d, J¼11.3 Hz, 1H), 7.15e7.41 (m, 20H);
13C NMR (100 MHz, CDCl3):
78.12, 80.92, 127.79, 127.91, 127.96, 128.08, 128.37, 128.41, 128.45,
136.90, 137.46, 137.55, 169.31. HMRS (ESI) calcd for C34H35O6
[MþH]: 539.2428. Found: 539.2423.
D
-glucono-1,5-lactone. Colorless oil;
;
1H NMR (400 MHz,
d
d
¼68.21, 73.52, 73.69, 73.91, 76.01,
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Acknowledgements
Financial support in the form of a Grant-in-Aid for Scientific
Research (No. 23655142) from the Ministry of Education, Culture,
Sports, Science, and Technology in Japan, and Iodine Research
Project in Chiba University is gratefully acknowledged.
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Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.tet.2012.06.026.
15. As a preliminary report: Tsuchiya, D.; Moriyama, K.; Togo, H. Synlett 2011, 2701.
16. Pelletier, G.; Bechara, W. S.; Charette, A. B. J. Am. Chem. Soc. 2010, 132, 12817.