Facile synthesis of symmetric thiosulfonates by oxidation of disulfide with oxone/MX (MX = KBr, KCl, NaBr and NaCl)

Article abstract of DOI:10.1016/j.tetlet.2015.05.050

Abstract A new method is described for the oxidation of aliphatic- and aromatic disulfides containing electron-donating and electron-withdrawing groups to their corresponding thiosulfonates using oxone in combination with the MX (MX = KBr, KCl, NaBr and NaCl). No obvious electronic effects influence the yields of thiosulfonates. Avoiding the usage of toxic and unstable reagents, mild reaction conditions, short reaction times and cost-effectiveness are advantages of this methodology when likened to known methods for thiosulfonates syntheses.

Full text of DOI:10.1016/j.tetlet.2015.05.050

Accepted Manuscript
Facile synthesis of symmetric thiosulfonates by oxidation of disulfide with ox-
one/MX (MX = KBr, KCl, NaBr and NaCl)
Palani Natarajan
PII:
S0040-4039(15)00859-X
DOI:
http://dx.doi.org/10.1016/j.tetlet.2015.05.050
TETL 46322
Reference:
To appear in:
Tetrahedron Letters
Received Date:
Revised Date:
Accepted Date:
13 April 2015
12 May 2015
14 May 2015
Please cite this article as: Natarajan, P., Facile synthesis of symmetric thiosulfonates by oxidation of disulfide with
oxone/MX (MX = KBr, KCl, NaBr and NaCl), Tetrahedron Letters (2015), doi: http://dx.doi.org/10.1016/j.tetlet.
2
015.05.050
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Facile synthesis of symmetric thiosulfonates
by oxidation of disulfide with oxone/MX
Leave this area blank for abstract info.
(MX = KBr, KCl, NaBr and NaCl)
Palani Natarajan

1
Tetrahedron Letters
journal homepage: www.elsevier.com
Facile synthesis of symmetric thiosulfonates by oxidation of disulfide with
oxone/MX (MX = KBr, KCl, NaBr and NaCl)
a,
Palani Natarajan ∗
a
Department of Chemistry & Centre for Advanced Studies in Chemistry, Panjab University, Chandigarh 160014, India
ARTICLE INFO
ABSTRACT
Article history:
Received
A new method is described for the oxidation of aliphatic- and aromatic disulfides containing
electron-donating and electron-withdrawing groups to their corresponding thiosulfonates using
oxone in combination with the MX (MX = KBr, KCl, NaBr and NaCl). No obvious electronic
effects influence the yields of thiosulfonates. Avoiding the usage of toxic and unstable reagents,
mild reaction conditions, short reaction times and cost-effectiveness are advantages of this
methodology when likened to known methods for thiosulfonates syntheses.
Received in revised form
Accepted
Available online
Keywords:
Keyword_1
Keyword_2
Keyword_3
Keyword_4
Keyword_5
2
015 Elsevier Ltd. All rights reserved.
Thiosulfonates have been used extensively in organic
1
synthesis, for the sulfenylation of various anions, as well as in
Oxone
KHSO ⋅KHSO
available effective oxidant.
(potassium
peroxymonosulfate,
5
4 2 4
⋅K SO , 2:1:1 molar ratio) is a commercially
2
biochemistry for the evolution of antimicrobial, antiviral,
19
Due to its high stability,
bactericidal and fungicidal agents. Therefore, considerable efforts
have been made in the development of both symmetric- and
nontoxicity, water-solubility, ready accessibility and high
efficiency, has been widely used for the oxidations of a wide
3
antisymmetric thiosulfonates. Among, the most frequently
19
range of functional groups including acetals, alcohols,
19
1
9
19
19
aldehydes, alkenes, amines, arenes, imines, nitroalkanes
19
19
19
employed method for the synthesis of symmetric thiosulfonates
involve the direct oxidation of disulfides in the presence of
various promoting reagents such as ceric ammonium
1
and oximes. But oxone has not yet been employed for the
9
synthesis of thiosulfonates.
4
5
nitrate/iodine, chlorine/acetic anhydride, 1-chloromethyl-4-
6
fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate),
In continuation of our interest on the HOBr mediated
20
oxidation of polycyclic aromatic hydrocarbons, I have found
that oxone combined with MX (MX = KBr, KCl, NaBr and
7
dibromo hydantoin, dinitrogen tetroxide/charcoal, dinitrogen
8
9
tetroxide
dichlorodioxomolybdenum, 1-fluoro-2,4,6-trimethylpyridinium
supported
on
poly(vinylpyrrolidone),
1
0
NaCl) in aqueous CH CN is an excellent reagent for the
3
1
1
conversion of disulfides to thiosulfonates. Herein, I report a novel
and efficient protocol (Scheme 1) for the synthesis of symmetric
thiosulfonates from their disulfides by hypohalous acids (HOX)
trifloromethanesulfonate,
hydrogen
peroxide/titanium
7
1
tetrachloride, 3-chloroperbenzoic acid, N-bromophthalimide,
2
13
1
4
7
N-bromosuccinimide,
1
N-chlorophthalimide,
chlorosuccinimide, scandium tris(trifluoromethanesulfonate),
N-
15
1
in situ generated by the hydrolysis of molecular halogens (Br
Cl ) produced from aqueous MX through oxone oxidation.
or
2
1
silica sulfuric acid/sodium nitrite, sodium periodate and zinc
6
17
2
1
8
dichromate trihydrate. However, many of these methods have
their own merits and demerits including long reaction times,
drastic reaction conditions, use of volatile and toxic organic
solvents, undesirable side reactions, laborious workup
procedures, usage of expensive reagents, special treatment for the
activation of the reagent and unsatisfactory yields. As a
consequence, the exploitation of highly practical and more
selective reagents is very desirable and remains a challenging
1
1
area for exploration.
Scheme 1. Oxone/MX mediated synthesis of thiosulfonates from
disulfides reported in this work.
—
——
∗
Corresponding author. Tel.: +0-000-000-0000; fax: +0-000-000-0000; e-mail: pnataraj@pu.ac.in (P. Natarajan)

2
Tetrahedron Letters
To screen the optimal reaction conditions, initial studies
reaction mixture was stirred for half an hour at room temperature,
diluted with water and extracted with ethyl acetate. The
were conducted using 1,2-diphenyldisulfide (1a) as a test
substrate and the outcomes are listed in Table 1. Investigations of
the model reaction, under identical reaction conditions, using
combined organic layers were dried over Na
2
SO
4
and
concentrated under reduced pressure to obtain expected product
in good to excellent yields.
various solvents such as acetone, CH
CCl ), chloroform (CHCl ), dichloromethane (DCM), dimethyl
sulfoxide (DMSO) and in combination with water (H O)
suggested that a mixture of CH CN and H O in 1:1 ratio was the
3
CN, carbon tetrachloride
(
4
3
Table 2. The effect of molar ratio of oxone and MX on the
oxidation of 1,2-diphenyldisulfide (1a).
2
3
2
best medium for thiosulfonates formation (Table 1, entry 4). This
likely reason is that water is necessary to dissolve oxone and KBr
3
since they have limited solubility in anhydrous CH CN.
Table 1. Solvent effect on the oxidation of 1,2-
diphenyldisulfide (1a) under identical reaction conditions.
a
a
Entry Oxone (mmol)
KBr (mmol)
Time (h)
Product Yield
b
(%)
c
1
2.0
2.0
3.0
1.0
1.0
1.0
2.0
3.0
0
0
24
NR
96
95
21
28
26
94
95
NR
NR
94
96
95
2
0.5
0.5
0.5
1.0
2.0
1.0
1.0
1.0
3.0
< 0.5
< 0.5
24
3
a
b
Entry
Solvent (v/v)
Time (h)
24
Product Yield (%)
4
1
2
3
4
5
6
7
8
9
acetone
trace
78
5
24
acetone-H
2
O (1:1)
24
6
24
CH
CH
CH
CH
CH
CH
3
3
3
3
3
3
CN
24
trace
96
7
< 0.5
< 0.5
24
CN-H
CN-H
CN-H
CN-H
CN-H
2
2
2
2
2
O (1:1)
O (7:3)
O (9:1)
O (3:7)
O (1:9)
< 0.5
24
8
c
c
87
9
24
41
10
11
12
13
14
15
16
17
0
24
d
6
93
2.0
2.0
2.0
2.0
3.0
2.0
3.0
0.5
0.5
0.5
0.5
24
e
24
34
0.5
c
f
CCl
CCl
4
24
NR
0.5
g
1
1
1
1
1
1
1
1
0
1
2
3
4
5
6
7
4
-H
2
O (1:1)
24
trace
0.5
trace
trace
trace
trace
c
g
CHCl
CHCl
DCM
3
24
NR
1.0
24
h
0.5
24
3
-H
2
O (1:1)
24
18
c
h
24
NR
1.0
24
DCM-H
2
O (1:1)
24
9
All reactions were run with 1a (1.0 mmol), MX (0-3 mmol) and oxone (0-3
a
3 2
mmol) in CH CN-H O (50:50, v/v) at room temperature. Oxone and MX
b c d
were recrystallized before use. Isolated yield. No reaction (NR). KCl used
DMSO
24
83
91
12
e
f
g
instead of KBr. NaBr used instead of KBr. NaCl used instead of KBr. KI
h
used instead of KBr. NaI used instead of KBr.
DMSO-H
2
O (1:1)
< 0.5
24
2
H O
a)
All reactions were run with 1a (1.0 mmol), KBr (2.0 mmol) and oxone (2.2
a
mmol) in various solvent at room temperature. Double distilled solvent and
b
c
millipore water were employed. Isolated yields. No reaction (NR).
Next, was attempted to arrive at an optimum stoichiometry of
the disulfide (1a) and the amount of KBr loading for the
b)
3
synthesis of thiosulfonates in aqueous CH CN (50:50, v/v, Table
1, entry 4) at room temperature. As shown in Table 2, higher
amounts of KBr neither increased the yield nor lowered the
reaction time drastically and the oxone was effective only in the
presence of KBr. The best result (96%, isolated yield) was
obtained by carrying out the reaction with a 1:0.5 mole ratio of
+
c)
1
a to KBr in the presence of oxone (2 moles) over 20 minutes.
1
Formation of the thiosulfonate of 1a was confirmed by the H
NMR measurements as well, cf. Figure 1. The easy recognizable
doublet of protons of 1a at δ = 7.24 ppm gradually down field
shifted to δ = 7.66 ppm and δ = 8.18 ppm corresponding to the
1
1
formation of the thiosulfonate (2a) within 20 minutes. It is
worthy to mention that in addition to the KBr, other alkali-metal
chlorides and bromides such as NaBr, KCl and NaCl also yielded
1
0
9
8
7
6
5
1
Figure 1. The H NMR (300 MHz) spectroscopic monitoring of
conversion of 1a into 2a in CD CN-D O (50:50, v/v) solution: (c) at
beginning of the reaction, (b) after 10 minutes, (a) after 20 minutes.
2
a in quantitative yield (Table 2). However, KI was not suitable
for this transformation as the oxidation reaction with oxone/KI or
oxone/NaI is sluggish. Thus, in typical experimental
procedure oxone (2.0 mmol) and MX (0.5 mmol) was dissolved
in mixture of CH CN-H O (50:50, v/v) at ambient conditions. To
this solution was added 1a (1.0 mmol). Subsequently, the
3
2
a
2
1
3
2

3
2
1
3
Table 3. Synthesis of thiosulfonates from disulfides by oxidation with oxone/KBr in aqueous CH CN.
a
b
Entry
1
R =
Substrate
Product
Time (min)
17
Yield (%)
96
mp (°C) (lit mp)
Ref.
4
1a
2a
38-42
(
38-39)
69-73
72-74)
56-59
57-58)
2
3
1b
1c
2b
2c
15
18
97
96
4
(
8a
(
4
1d
2d
40
91
48-53
49-52)
7b
(
5
6
1e
1f
2e
2f
30
22
93
92
88-91
89-90)
68-74
67-71)
12
9
(
(
7
8
9
1g
1h
1i
2g
2h
2i
20
18
19
17
22
20
20
25
28
92
94
91
93
90
94
92
91
89
180-184
182)
70-72
69-70)
134-137
135-136)
157-160
158-159)
oil
12
4
(
(
4
(
10
11
12
13
14
15
1j
2j
4
(
1k
1l
2k
2l
12
4
(
oil)
oil
(
oil)
1m
1n
1o
2m
2n
2o
oil
9
(
oil)
oil
12
9
(
oil)
oil
(
oil)
a
O (50:50, v/v) at room temperature. The products were
All reactions were run with 1 (1.0 mmol), MX (0.5 mmol) and oxone (2.0 mmol) in CH
b
characterized by their comparison with known compounds. Isolated yield.
3
CN-H
2
With the optimized reaction conditions in hand (Tables 1 and
(1h), 4-chlorophenyl disulfide (1i) and 4-bromophenyl disulfide
22
(1j), gave high yields of corresponding thiosulfonates under
21
2
), the oxidation of various alkyl- and aryl disulfides was
examined to explore the scope of the present protocol (Scheme
). As shown in Table 3, a series of aromatic disulfides bearing
optimal conditions (Tables 1, 2 and 3). Moreover, this system is
also applicable to the efficient oxidation of alkyl disulfides (1k-
1o, Table 3) into representing products in 89-94% yields (Table
3, Entries 12-15).
1
either electron-donating or electron-withdrawing groups on the
aromatic ring were investigated. The substitution groups on the
aromatic ring associated with disulfides had little effect on the
yields, cf. Table 3. For examples, electron-rich disulfides such as
4
-tolyl disulfide (1b), 2-tolyl disulfide (1d), 4-anisyl disulfide
1e) and 3-anisyl disulfide (1f), and electron-deficient disulfides
such as 4-nitrophenyl disulfide (1g), 4-fluorophenyl disulfide
(

4
Tetrahedron Letters
X
S
O
S
O
O
S
i)
O
R
O
S
X
H
R
R
S
R
R
H
S
R
R
S
-
HX
R
S
O
ii) OH
iii) -HX
O
2KHSO5 KHSO4
K SO + MX
2
4
OH
-
K S O
KHSO4
K SO
2 4
2
2
8
S
R
X
S
R
S
O
R
+ MOH
1/2 Br + 1/2 H O + MOH
2
2
2
X
H
R
S
-
OH
1+
Figure 2. The proposed reaction mechanism for the synthesis of thiosulfonates from disulfides.
Next, was attempted to synthesis unsymmetric thiosulfonates
Acknowledgements
from unsymmetrical disulfides under standard conditions
described in Tables 1 and 2 for the preparation of symmetric
thiosulfonates (2a-2o, Table 3). However, this procedure cannot
be suitable for the synthesis of unsymmetric thiosulfonates as a
mixture of products (Scheme 2) were noticed. It is believed that
P.N. gratefully acknowledges the financial support from the
Department of Science & Technology (DST), India through
INSPIRE Faculty Fellowship [IFA12-CH-62].
11
the oxidation proceeds via the formation of hypohalous acid,
which has higher instability due to pronounced ionic nature and
thus more reactivity towards the disulfides leading to a mixture
Supplementary data
7
Supplementary data (NMR and IR spectra of some selected
products) associated with this article can be found, in the online
version, at http://dx.doi.org/10.1016/j.tetlet.0000.00. 000.
of products.
References and notes
1
2
3
4
. Andrushko, V.; Andrushko, N. Stereoselective Synthesis of Drugs and
Natural Products; John Wiley & Sons: New York, 2013.
. Acton, A. Pharmaceuticals - Advances in Research and Application;
Scholarly Editions: 2012.
. (a) Steudel, R. Chem. Rev. 2002, 102, 3905–3946; (b) Xu, X.-H.;
Matsuzaki, K.; Shibata, N. Chem. Rev. 2015, 115, 731–764.
. Cai, M.-T.; Lv, G.-S.; Chen, J.-X.; Gao, W.-X.; Ding, J.-C.; Wu, H.-Y.
Chem. Lett. 2010, 39, 368–369.
Scheme 2. Oxone/KBr mediated synthesis of unsymmetric
thiosulfonates from unsymmetric disulfides. Reaction conditions:
disulfide (1.0 mmol), KBr (0.5 mmol) and oxone (2.0 mmol) in
CH CN-H O (50:50, v/v), rt. Yields given in parenthesis were
3
2
determined by GC analysis.
5. Buckman, J. D.; Bellas, M.; Kim, H. K.; Field, L. J. Org. Chem. 1967, 32,
626–1627.
1
6
. Kirihara, M.; Naito, S.; Ishizuka, Y.; Hanai, H.; Noguchi, T. Tetrahedron
Lett. 2011, 52, 3086–3089.
The plausible reaction mechanism for the preparation of
thiosulfonates from disulfides is outlined in Figure 2 on the basis
of blank experiments and an earlier proposed mechanism. To
understand the role of MX and oxone in the synthesis of
thiosulfonates, I carried out blank experiments with disulfides
and MX (in the absence of oxone, Table 2, entries 9 and 10) as
well as disulfides and oxone (in the absence of MX, Table 2,
entry 2), and the reactions did not succeed. Therefore, both MX
and oxone played an important role in the product formation. It is
7
. (a) Mundy, B. P.; Ellerd, M. G.; Favaloro, Jr. F. G. Name Reactions and
Reagents in Organic Synthesis; John Wiley & Sons: New York, 2005; (b)
Xu, Y.; Peng, Y.; Sun, J.; Chen, J.; Ding, J.; Wu, H. J. Chem. Res. 2010,
3
4, 358–360.
. (a) Iranpoor, N.; Firouzabadi, H.; Pourali, A.-R. Synlett. 2004, 347–349;
b) Iranpoor, N.; Firouzabadi, H.; Pourali, A.-R. Phosphorus, Sulfur, and
8
(
Silicon, 2006, 181, 473–479.
−
9
1
1
. Iranpoor, N.; Firouzabadi, H.; Pourali, A.-R. Tetrahedron 2002, 58, 5179–
well-known that oxidation of halide ion (X ) by oxone affords the
1
9,23
5
184.
molecular halogens (X
hydroxyl ion or water to form HOX (Figure 2).
HOX will react with the disulfide to give a cationic intermediate
1+) that further undergo nucleophile attack by hydroxyl
2
),
which can react with either
1
9,20
0. Sanz, R.; Escribano, J.; Aguado, R.; Pedrosa, M. R.; Arnáiz, F. J.
Synthesis, 2004, 1629–1632.
Eventually,
1. Kirihara, M.; Naito, S.; Nishimura, Y.; Ishizuka, Y.; Iwai, T.; Takeuchi,
H.; Ogata, T.; Hanai, H.; Kinoshita, Y.; Kishida, M.; Yamazaki, K.;
Noguchi, T.; Yamashoji, S. Tetrahedron 2014, 70, 2464–2471.
2. Bahrami, K.; Khodaei, M. M.; Khaledian, D. Tetrahedron Lett. 2012, 53,
(
ion/water to produce a thiosulfonate, cf. Figure 2.
In summary, a novel method is described for the synthesis of
thiosulfonates from disulfides by oxidation using oxone in
combination with the alkali-metal chlorides and bromides.
Reactions proceed smoothly in environmentally benign solvents
yielding expected product in good to excellent yields. Mild and
simple reaction conditions, inexpensive reagents and non-
1
1
1
1
3
54–358.
3. Perrone, E.; Alpegiani, M.; Bedeschi, A.; Borghi, D.; Giudici, F.;
Franceschi, G. J. Org. Chem. 1986, 51, 3413–3420.
4. Gaigai, L.; Miaochang, L.; Jiuxi, C.; Jinchang, D.; Wenxia, G.; Huayue,
W. Chin. J. Chem. 2012, 30, 1611—1616.
polluting byproducts make this method valuable from
preparative point of perspectives.
a
5. Liang, G.; Chen, J.; Chen, J.; Li, W.; Chen, J.; Wu, H. Tetrahedron Lett.
2
012, 53, 6768–6770.

5
1
1
6. Zolfigol, M. A. Tetrahedron, 2001, 57, 9509–9511.
7. Takata, T.; Kim, Y. H.; Oae, S. Bull. Chem. Soc. Jpn. 1981, 54, 1443–
1
447.
1
1
2
8. Hassani, H. Chin. J. Chem. 2009, 27, 1012–1014.
9. Hussain, H.; Green, I. R.; Ahmed, I. Chem. Rev. 2013, 113, 3329–3371.
0. (a) Natarajan, P.; Vagicherla, V. D.; Vijayan, M. T. Tetrahedron Lett.
2
014, 55, 3511–3515; (b) Natarajan, P.; Vagicherla, V. D.; Vijayan, M.
T. Tetrahedron Lett. 2014, 55, 5817–5821.
2
1. General Aspects: Solvents were distilled prior to use and millipore water
was used for preparing aqueous solutions. All commercial chemicals
were used as received. All reactions were carried out in an open
atmosphere. Reactions were monitored by analytical thin layer
chromatography (TLC) on silica gel (Merck). NMR spectra were
recorded on a Bruker Avance 300 MHz spectrometer in deuterated
solvents. Melting points were determined on a FEC hotplate apparatus.
General Procedure for Synthesis of Thiosulfonates from Disulfides:
Oxone (2.0 mmol) was added to a well-stirred solution of MX (KBr, KCl,
NaBr and NaCl, 0.5 mmol) in aqueous acetonitrile (50:50, v/v), followed
by substrate (1.0 mmol) was added. Resulting mixture was stirred for the
appropriate period of time (Table 3) at room temperature. After complete
consumption of the starting material as observed by TLC, water (50 mL)
was added and the mixture was extracted with ethyl acetate. The extract
was washed with brine, dried over anhydrous sodium sulfate and
evaporated to afford the corresponding thiosulfonate as the sole product.
It was further recrystallized using mixture of ethyl acetate and petroleum
ether to remove color impurities. All of the products are known
compounds and were characterized by comparison with authentic
samples (NMR spectra and melting points).
2
2. Some of the products obtained in this study were characterized by NMR,
IR and elemental analysis:
4
Diphenyl thiosulfonate (2a): Yield (96%), mp 38-42 °C (lit. mp 38-39
–1
ºC). IR (KBr, cm ): 3054, 1620, 1381, 1310, 1131, 1142, 1000, 820, 750,
1
13
6
90. H NMR (CDCl
ppm): 127.49, 128.01, 128.54, 129.37, 131.31, 134.01, 136.54, 142.83.
Anal. calcd for C12 : C, 57.57; H, 4.03. Found: C, 57.33; H, 4.04.
,4′-Dimethylphenyl thiosulfonate (2b): Yield (97%), mp 69-73 °C (lit.
mp 71-72 °C). IR (KBr, cm ): 3031, 2918, 1614, 1379, 1319, 1141,
3 3
) δ (ppm): 7.31-7.82 (10H, m). C NMR (CDCl ) δ
(
10 2 2
H O S
4
4
–1
1
1
7
003, 817, 754. H NMR (CDCl
.14-7.16 (2H, m), 7.21-7.29 (4H, m), 7.49-7.82 (2H, m). C NMR
) δ (ppm): 21.52, 21.64, 125.04, 127.61, 129.37, 130.09, 136.54,
3
) δ (ppm): 2.37 (3H, s), 2.43 (3H, s),
13
(
CDCl
3
1
6
4
40.42, 145.02. Anal. calcd for C14
14 2 2
H O S : C, 60.40; H, 5.07. Found: C,
0.29; H, 5.11.
1
,4′-Dimethoxyphenyl thiosulfonate (2e): Yield (93%), mp 88-91 °C
2
–
lit. mp 89-90 °C). IR (KBr, cm ): 3043, 1632, 1382, 1320, 1132, 1008,
1
(
1
8
14, 752. H NMR (CDCl
4H, m), 7.20 (2H, d, J = 8.9 Hz), 7.46 (2H, d, J = 8.9 Hz). C NMR
CDCl ) δ (ppm): 55.61, 55.64, 113.78, 114.90, 118.91, 129.89, 134.88,
38.37, 162.19, 163.48. Anal. calcd for C14 : C, 54.17; H, 4.55.
Found: C, 54.19; H, 4.51.
,4′-Dichlorophenyl thiosulfonate (2i): Yield (91%), mp 134-137 °C
lit. mp 135-136 °C). IR (KBr, cm ): 3032, 2984, 1631, 1572, 1454,
3
) δ (ppm): 3.78 (3H, s), 3.83 (3H, s), 6.76-6.83
1
3
(
(
3
1
14 4 2
H O S
4
4
–1
(
1
133, 1141, 1084, 1002, 810, 753. H NMR (CDCl
1
3
) δ (ppm): 7.28 (2H,
d, J = 8.4 Hz), 7.37 (2H, d, J = 8.4 Hz), 7.44 (2H, d, J = 8.6 Hz), 7.51
1
3
(
2H, d, J = 8.6 Hz). C NMR (CDCl
3
) δ (ppm): 125.96, 129.02, 129.24,
29.86, 137.71, 138.49, 140.51, 141.32. Anal. calcd for C12 Cl : C,
5.15; H, 2.53. Found: C, 45.12; H, 2.53.
1
4
H
8
2 2 2
O S
2
3. Dieter, R. K.; Nice, L. E.; Sadanandan, E. V. Tetrahedron Lett. 1996, 37,
377–2380.
2