Metal cation-exchanged montmorillonite-catalyzed addition of organic disulfides to alkenes

Article abstract of DOI:10.1246/bcsj.78.1138

The addition of organic disulfides to alkenes, giving vic-bis(alkylthio) alkanes and vic-bis(arylthio)alkanes, proceeds in chlorobenzene in the presence of a catalytic amount of a variety of metal cation-exchanged montmorillonites (abbreviated as Mⁿ⁺

Full text of DOI:10.1246/bcsj.78.1138

1138 Bull. Chem. Soc. Jpn., 78, 1138–1141 (2005)
Ó 2005 The Chemical Society of Japan
Metal Cation-Exchanged Montmorillonite-Catalyzed Addition
of Organic Disulfides to Alkenes
ꢀ
ꢀ
Takahiro Nishimura, Tomoaki Yoshinaka, and Sakae Uemura
Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering,
Kyoto University, Nishikyo-ku, Kyoto 615-8510
Received December 22, 2004; E-mail: tnishi@kuchem.kyoto-u.ac.jp
The addition of organic disulfides to alkenes, giving vic-bis(alkylthio)alkanes and vic-bis(arylthio)alkanes, pro-
ceeds in chlorobenzene in the presence of a catalytic amount of a variety of metal cation-exchanged montmorillonites
(abbreviated as Mnþ-monts), Al3þ, Fe3þ, Zr4þ, and In3þ being effective as Mnþ. The most effective Fe3þ-mont can
be reused for the addition of diphenyl disulfide to cyclohexene at least 8 times without an appreciable loss of catalytic
activity.
Organic syntheses using the solid catalysts such as silicas,
Table 1. Effect of Mnþ-mont
aluminas, clays, zeolites, and polymers under mild conditions
SPh
SPh
cat. Mn+-mont (50 mg)
have been well-developed.1 Among a variety of solid catalysts,
metal cation-exchanged montmorillonites are known to be
among the useful and environmentally friendly clay catalysts
that have many advantages over others, such as an ease of
handling, noncorrosiveness, low cost, and reusability.
S
Ph
+
Ph
S
PhCl (1 mL)
50 °C, 3 h
1.5 mmol
0.25 mmol
Entry
Catalyst
K10
Acid sites/mmola)
GLC yield/%b)
1
2
0.016
0.027
0.017
0.037
0.0098
0
0.019
0.016
0.017
89
78
96
98
85
0
9
21
96
The addition of organic disulfides to alkenes is one of the
useful reactions to synthesize various sulfur-containing com-
pounds. Several reports on this type of reaction have appeared
so far (Eq. 1) using either a stoichiometric or a catalytic
Al3þ-mont
Fe3þ-mont
Zr4þ-mont
In3þ-mont
Naþ-mont
Zn2þ-mont
K10
3c)
4
5c)
6
amount of a variety of acids, such as GaCl3,2 Me2O BF3,3
ꢁ
and PhIO–TfOH4 or a catalytic amount of a transition metal
7
ꢀ
complex such as [Cp RuCl(cod)].5
8d)
9d)
Fe3þ-mont
R'
S
R
H+
a) The amount of acid sites of Mnþ-mont was estimated by
NH3-TPD analysis. b) Biphenyl was used as an internal stan-
dard. c) We also examined the addition of diphenyl disulfide
to cyclohexene catalyzed by transiton metal chlorides under
similar reaction conditions. The addition catalyzed by FeCl3
(0.017 mmol equal to 50 mg Fe3þ-mont) and InCl3 (0.0098
mmol equal to 50 mg In3þ-mont) afforded trans-1,2-bis(phen-
ylthio)cyclohexane only in 21% yield and in 28% yield, re-
S
R'
+
R'
S
R
R
R
R'S-H+
ð1Þ
SR'
R
R
- H+
SR'
ꢂ
On the other hand, Clark and co-workers reported the reac-
tion of dimethyl disulfide with cyclohexene in the presence of
a stoichiometric amount of K-10 montmorillonite and excess
ZnCl2, but due to the formation of dithioalkane-ligated Zn-
complexes, it was difficult to reuse these reagents.6
spectively. d) At 20 C for 24 h.
was investigated in chlorobenzene as solvent (Table 1). Many
Mnþ-monts (especially Fe3þ-mont, Zr4þ-mont, and In3þ-mont)
as well as K-10 worked as efficient catalysts to give trans-1,2-
bis(phenylthio)cyclohexane in high yields (entries 1–5) stereo-
selectively, while some Mnþ-monts such as Naþ-mont and
Zn2þ-mont were not effective (entries 6 and 7). From these
results together with economical and environmental concerns,
we chose Fe3þ-mont as a catalyst for further examination.
Next, the addition of diphenyl disulfide to cyclohexene
was carried out in various kinds of solvents (Table 2). Among
the solvents examined were chlorobenzene, fluorobenzene,
toluene, 1,2-dichloroethane, ethyl acetate, chloroform, DMF
(N,N-dimethylformamide), and DME (1,2-dimethoxyethane)
As one of our series of studies in the use of clay catalysts for
useful organic transformations,7 we have now investigated the
addition of organic disulfides to alkenes in the presence of a
catalytic amount of Mnþ-mont and found that some Mnþ
-
monts show a high reactivity for this reaction under mild con-
ditions.
Results and Discussion
First, the catalytic activity of a variety of Mnþ-moꢂnts for the
addition of diphenyl disulfide to cyclohexene at 50 C for 3 h
Published on the web June 6, 2005; DOI 10.1246/bcsj.78.1138

T. Nishimura et al.
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1139
Table 2. Effect of Solvent
The addition of various organic disulfides to cyclohexene
was also investigated; typical results are listed in Table 4.8
A variety of diaryl disulfides can be available, but not di(2-pyr-
idyl) disulfide (entries 1–6). Dialkyl disulfides, such as diben-
zyl disulfide, dipropyl disulfide, dicyclohexyl disulfide, and
bis[2-(ethoxycarbonyl)ethyl] disulfide reacted to give the
corresponding 1,2-dithioalkanes in moderate to good yields
(entries 7–10). The use of bis(4-methoxyphenyl) disulfide,
bis(4-nitrophenyl) disulfide, bis(6-hydroxy-2-naphthyl) di-
sulfide, or N,N0-dithiobisphthalimide, however, failed to give
the corresponding sulfur-containing product. Further, the reac-
tion of diphenyl diselenide with cyclohexene did not afford the
corresponding selenium-containing product at all.
Considering the trans stereochemistry of the products as
well as Lewis acid nature of Mnþ-mont, we conclude that all
of the reactions proceed via an episulfonium ion shown in
Eq. 1 and give trans-bis(alkylthio)alkanes and trans-bis(aryl-
thio)alkanes. However, we do not have any more experimental
evidence to discuss the reaction pathway in detail at the pres-
ent.
Fe3+-mont (50 mg;
SPh
SPh
0.017 mmol as acid sites)
S
Ph
+
Ph
S
solvent (1 mL)
50 °C, 3 h
1.5 mmol
0.25 mmol
Entry
Solvent
Conv./%a)
GLC yield/%b)
1
2
3
4
5
6
7
8
PhCl
PhF
Toluene
1,2-Dichloroethane
AcOEt
CHCl3
DMF
DME
97
63
74
54
0
0
0
0
96
63
65
53
0
0
0
0
a) Conversion of diphenyl disulfide. b) Biphenyl was used as
an internal standard.
Table 3. Addition of Diphenyl Disulfide to a Variety of
Alkenes
Finally, the reusability of Fe3þ-mont was investigated in the
reaction of ꢂdiphenyl disulfide with cyclohexene in chloroben-
zene at 50 C. After 5 h, the reaction mixture was cooled to
room temperature. Then, the catalyst was removed by the cen-
trifuge, washed with acetone three times, and dried in vacuo at
Fe3+-mont (50 mg;
0.017 mmol as acid sites)
R
PhS
R
R
S
Ph
+
Ph
S
PhCl (1 mL), 50 °C
R
SPh
1.5 mmol
0.25 mmol
ꢂ
Entry
1
Product
Time/h Isolated yield/%
room temperature, and then at 120 C for 5 h under an atmo-
SPh
spheric pressure. The use of this recovered catalyst gave the
same product in a high yield for the next run. It was revealed
that by this procedure Fe3þ-mont could be used for this addi-
tion at least 8 times, as shown in Table 5.
In conclusion, metal cation-exchanged montmorillonites
(Mnþ-monts) were revealed to be efficient catalysts for the
addition of a variety of organic disulfides to various alkenes,
where Fe3þ-mont was most effective. Fe3þ-mont could be
reused at least 8 times in the addition of diphenyl disulfide
to cyclohexene.
5
95
SPh
SPh
2
3
5
98
96
SPh
SPh
12
SPh
SPh
4aÞ
5aÞ
6aÞ
24
27
96
34
89
58
SPh
SPh
Experimental
SPh
SPh
General Method. 1H NMR spectra were obtained in CDCl3 at
270, 300, or 400 MHz with Me4Si as an internal standard.
13C NMR spectra were obtained at 67.8, 75.5, or 100 MHz. Ele-
mental analyses were performed at the Microanalytical Center
of Kyoto University.
SPh
a) Fe3þ-mont (200 mg; 0.068 mmol as acid sites).
Materials. All commercially available organic and inorganic
compounds were used without further purification. Kunipia G,
namely Naþ-mont, was obtained from Kunimine Industries Co.,
Ltd. Montmorillonite K-10 was commercially available from
(entries 1–8); chlorobenzene was revealed to be the solvent of
choice (entry 1).
The results of diphenyl disulfide addition to a variety of al-
kenes are shown in Table 3.8 Cyclopentene, cyclohexene, and
cycloheptene reacted smoothly to give the corresponding sul-
fur-containing products in high yields (entries 1–3). Cyclooc-
tene was also converted to the corresponding product by using
a larger amount of catalyst, but in a low yield (entry 4). The
reactions of linear alkenes, such as 1-octene and 7-tetradecene,
also gave the corresponding 1,2-dithioalkanes in moderate
yield (entries 5 and 6). The treatment of alkenes, such as sty-
rene, 4-methoxystyrene, trans-stilbene, indene, norbornene,
3,4-dihydropyran, propyl vinyl ether, and allyl alcohol, un-
fortunately, did not afford the corresponding products at all.
Further, no reaction occurred between diphenyl disulfide and
1-octyne.
Aldrich Chemical Co., Inc. Mnþ-monts (Mnþ ¼ Fe3þ, Zr4þ
,
In3þ, Al3þ, and Zn2þ) were prepared by treatment of Naþ-mont
with the corresponding metal chloride oxide or nitrate in aqueous
acetone, as described previously.7,9
Typical Procedure for Addition Reaction of Organic Di-
sulfides to Alkenes Catalyzed by Metal Cation-Exchanged
Montmorillonite.
To a mixture of diphenyl disulfide (54.6
mg, 0.25 mmol), Fe3þ-mont (50 mg, 0.017 mmol as active acid
sites), and chlorobenzene (1 mL) in a 5-mL test tube was added
cyclohexene (0.15 mL, 1.50 mmol) and the mixture was then stir-
red at 50 ꢂC for 5 h. The reaction mixture was cooled to room tem-
perature and then the catalyst was separated by filtration through a
glass filter. For the isolation of the product, the solvent was evapo-

1140 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Table 4. Addition of a Variety of Organic Disulfides to Cyclohexene
Addition of Organic Disulfides to Alkenes
Fe3+-mont (200 mg;
0.068 mmol as acid sites)
SR
SR
S
R
+
R
S
PhCl (1 mL), 50 °C
0.25 mmol
1.5 mmol
Entry
1
Product
Time/h
24
Isolated yield/%
91
S
S
2a)
3
4
5
X = H
Me
Cl
5
14
24
24
98
85
50
66
X
S
S
X
Br
S
S
N
N
6
7
40
13
S
S
S
S
72
68
8
9
24
24
24
73
S
S
S
S
51
EtO
OEt
O
10b)
42c)
O
a) Fe3þ-mont (50 mg; 0.017 mmol as acid sites). b) Five-fold scale reaction. c) Isolated by HPLC.
Table 5. Reusability of Fe3þ-mont
Fe3+-mont (200 mg;
SPh
0.068 mmol as acid sites)
S
Ph
+
Ph
S
PhCl (4 mL), 50 °C, 5 h
SPh
6 mmol
1 mmol
Run
Conv./%
GLC yield/%a)
Run
Conv./%
GLC yield/%a)
1st
2nd
3rd
4th
95
98
98
98
94
98
98
98
5th
6th
7th
8th
91
91
97
72
91
86
97
72
a) Biphenyl was used as an internal standard.
rated and the residue was purified by column chromatography
(Merck silica gel 60; hexane/ethyl acetate as an eluent).
(67.8 MHz, CDCl3) ꢀ 23.9, 28.5, 30.4, 53.2, 126.7, 128.8,
131.8, 135.2.
trans-1,2-Bis(phenylthio)cyclopentane.4
Colorless oil;
trans-1,2-Bis(phenylthio)cyclooctane.
(neat) 2924, 2850, 1479, 1438, 737, 691 cmꢃ1
Colorless oil; IR
1H NMR (400
1H NMR (300 MHz, CDCl3) ꢀ 1.67–1.77 (m, 2H), 1.82–1.91
(m, 2H), 2.30–2.41 (m, 2H), 3.55–3.58 (m, 2H), 7.19–7.25 (m,
10H); 13C NMR (75.5 MHz, CDCl3) ꢀ 23.1, 30.9, 52.7, 126.7,
128.9, 131.2, 135.4.
;
MHz, CDCl3) ꢀ 1.43–1.62 (m, 6H), 1.77–1.93 (m, 4H), 2.17–
2.25 (m, 2H), 3.42–3.47 (m, 2H), 7.19–7.38 (m, 10H); 13C NMR
(100 MHz, CDCl3) ꢀ 25.2, 26.3, 29.0, 52.9, 126.7, 128.8, 131.9,
135.5. Anal. Calcd for C20H24S2: C, 73.12; H, 7.36; S, 19.52%.
Found: C, 73.22; H, 7.47; S, 19.78%.
1,2-Bis(phenylthio)octane.5 Yellow oil; IR (neat) 2928, 2855,
1480, 1438, 738, 691 cmꢃ1; 1H NMR (400 MHz, CDCl3) ꢀ 0.88 (t,
J ¼ 6:6 Hz, 3H), 1.24–1.62 (m, 9H), 1.93–2.01 (m, 1H), 2.89 (dd,
J ¼ 13:5, 9.8 Hz, 1H), 3.09–3.16 (m, 1H), 3.25 (dd, J ¼ 13:5, 4.2
Hz, 1H), 7.17–7.33 (m, 10H); 13C NMR (100 MHz, CDCl3) ꢀ
trans-1,2-Bis(phenylthio)cyclohexane.4
Colorless oil;
1H NMR (270 MHz, CDCl3) ꢀ 1.40–1.69 (m, 6H), 2.21–2.30
(m, 2H), 3.24–3.31 (m, 2H), 7.21–7.33 (m, 10H); 13C NMR
(67.8 MHz, CDCl3) ꢀ 23.5, 29.8, 49.6, 126.9, 128.8, 132.2, 134.6.
trans-1,2-Bis(phenylthio)cycloheptane.4
Colorless oil;
1H NMR (270 MHz, CDCl3) ꢀ 1.54–1.90 (m, 8H), 2.14–2.24
(m, 2H), 3.44–3.51 (m, 2H), 7.18–7.28 (m, 10H); 13C NMR

T. Nishimura et al.
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1141
14.2, 22.7, 26.8, 29.1, 31.7, 32.6, 39.4, 48.4, 126.2, 127.1, 128.8,
128.9, 129.7, 132.4, 134.3, 135.8. Anal. Calcd for C20H26S2: C,
72.67; H, 7.93; S, 19.40%. Found: C, 72.94; H, 7.95; S, 19.51%.
trans-1,2-Bis(propylthio)cyclohexane.
(neat) 2959, 2931, 2870, 2855, 1456, 1445 cmꢃ1; H NMR (270
Colorless oil; IR
1
MHz, CDCl3) ꢀ 0.93 (t, J ¼ 7:3 Hz, 6H), 1.19–1.65 (m, 10H),
2.07–2.15 (m, 2H), 2.49 (t, J ¼ 7:2 Hz, 4H), 2.67–2.74 (m, 2H);
13C NMR (67.8 MHz, CDCl3) ꢀ 13.6, 23.1, 24.0, 31.4, 33.6,
48.3. Anal. Calcd for C12H24S2: C, 62.00; H, 10.41; S, 27.59%.
Found: C, 61.92; H, 10.61; S, 27.35%.
trans-7,8-Bis(phenylthio)tetradecane.
(neat) 2954, 2927, 2855, 1584, 1479, 1466, 1438, 744, 691
cmꢃ1
Colorless oil; IR
;
1H NMR (400 MHz, CDCl3) ꢀ 0.86 (t, J ¼ 6:8 Hz, 6H),
1.17–1.43 (m, 14H), 1.49–1.55 (m, 2H), 1.61–1.70 (m, 2H),
1.74–1.83 (m, 2H), 3.30 (dt, J ¼ 11:2, 4.3 Hz, 2H), 7.16–7.26
(m, 6H), 7.33–7.36 (m, 4H); 13C NMR (100 MHz, CDCl3) ꢀ
14.1, 22.6, 27.5, 29.0, 31.7, 32.6, 55.1, 126.5, 128.7, 131.6,
136.4. Anal. Calcd for C26H38S2: C, 75.30; H, 9.24; S, 15.46%.
Found: C, 75.40; H, 9.36; S, 15.25%.
trans-1,2-Bis(cyclohexylthio)cyclohexane. Colorless oil; IR
1
(neat) 2928, 2851, 1446, 1263, 1198, 1000 cmꢃ1; H NMR (300
MHz, CDCl3) ꢀ 1.24–2.19 (m, 28H), 2.68–2.76 (m, 2H), 2.88–
2.94 (m, 2H); 13C NMR (75.5 MHz, CDCl3) ꢀ 23.4, 25.9, 26.2,
31.2, 34.0, 43.6, 46.7. Anal. Calcd for C18H32S2: C, 69.16; H,
10.32; S, 20.52%. Found: C, 68.86; H, 10.18; S, 20.34%.
trans-1,2-Bis[2-(ethoxycarbonyl)ethylthio]cyclohexane.
trans-1,2-Bis(p-tolylthio)cyclohexane.
(neat) 2931, 2854, 1491, 1445, 810 cmꢃ1
Colorless oil; IR
1H NMR (270 MHz,
;
CDCl3) ꢀ 1.32–1.42 (m, 2H), 1.54–1.68 (m, 4H), 2.15–2.22 (m,
2H), 2.33 (s, 6H), 3.12–3.20 (m, 2H), 7.06 (dd, J ¼ 7:9, 0.5 Hz,
4H), 7.24 (d, J ¼ 8:2 Hz, 4H); 13C NMR (67.8 MHz, CDCl3) ꢀ
21.2, 23.7, 30.2, 50.0, 129.5, 130.8, 132.9, 137.1. Anal. Calcd
for C20H24S2: C, 73.12; H, 7.36; S, 19.52%. Found: C, 73.34;
H, 7.47; S, 19.35%.
Colorless oil; IR (neat) 2980, 2931, 1735, 1371, 1243, 1178 cmꢃ1
;
1H NMR (400 MHz, CDCl3) ꢀ 1.27 (t, J ¼ 7:1 Hz, 6H), 1.31–1.40
(m, 2H), 1.48–1.55 (m, 2H), 1.67–1.71 (m, 2H), 2.15–2.20 (m,
2H), 2.60 (t, J ¼ 7:4 Hz, 4H), 2.74–2.80 (m, 2H), 2.85 (t, J ¼
7:4 Hz, 4H), 4.16 (q, J ¼ 7:1 Hz, 4H); 13C NMR (100 MHz,
CDCl3) ꢀ 14.3, 24.2, 26.6, 31.9, 35.0, 48.9, 60.7, 171.8. Anal.
Calcd for C16H28O4S2: C, 55.14; H, 8.10; S, 18.40%. Found: C,
55.09; H, 8.20; S, 18.67%.
trans-1,2-Bis(2-naphthylthio)cyclohexane.
mp ¼ 102:2{102:7 ꢂC; IR (KBr) 2930, 2913, 822, 740, 480,
469 cmꢃ1 1H NMR (300 MHz, CDCl3) ꢀ 1.36–1.65 (m, 6H),
White solid,
;
2.23–2.31 (m, 2H), 3.36 (br s, 2H), 7.27–7.71 (m, 14H); 13C NMR
(75.5 MHz, CDCl3) ꢀ 23.4, 29.9, 49.7, 126.1, 126.4, 127.3, 127.6,
128.4, 129.8, 130.9, 132.1, 132.3, 133.6. Anal. Calcd for
C26H24S2: C, 77.95; H, 6.04; S, 16.01%. Found: C, 77.70; H,
6.11; S, 16.01%.
References
1
For reviews on organic reactions in the presence of solid
catalysts, see for example: a) P. Laszlo, ‘‘Preparative Chemistry
Using Supported Reagents,’’ Academic Press, New York (1987).
b) Y. Izumi, K. Urabe, and M. Onaka, ‘‘Zeolite, Clay, and Hetero-
poly Acid in Organic Reactions,’’ VCH, Weinheim (1992). c) K.
Smith, ‘‘Solid Supports and Catalysts in Organic Synthesis,’’ Ellis
Horwood, London (1992). d) M. Balogh and P. Laszlo, ‘‘Organic
Chemistry Using Clays,’’ Springer-Verlag, New York (1993). e)
J. H. Clark, ‘‘Catalysis of Organic Reactions Using Supported
Inorganic Reagents,’’ VCH, New York (1994).
trans-1,2-Bis(4-chlorophenylthio)cyclohexane.
Colorless
1
oil; IR (neat) 2933, 2855, 1475, 1094, 1012, 819 cmꢃ1; H NMR
(270 MHz, CDCl3) ꢀ 1.36–1.43 (m, 2H), 1.61–1.67 (m, 4H), 2.16–
2.23 (m, 2H), 3.10–3.17 (m, 2H), 7.21–7.29 (m, 8H); 13C NMR
(67.8 MHz, CDCl3) ꢀ 23.7, 30.4, 50.3, 129.0, 132.9, 133.3,
133.9. Anal. Calcd for C18H18Cl2S2: C, 58.53; H, 4.91; S,
17.36%. Found: C, 58.65; H, 5.05; S, 17.60%.
trans-1,2-Bis(4-bromophenylthio)cyclohexane.
Colorless
2
Org. Lett., 6, 601 (2004).
3 M. C. Caserio, C. L. Fisher, and J. K. Kim, J. Org. Chem.,
50, 4390 (1985).
4 T. Kitamura, J.-I. Matsuyuki, and H. Taniguchi, J. Chem.
Soc., Perkin Trans. 1, 1991, 1607.
S.-I. Usugi, H. Yorimitsu, H. Shinokubo, and K. Oshima,
oil; IR (neat) 2932, 1472, 1091, 1009, 817 cmꢃ1; H NMR (270
MHz, CDCl3) ꢀ 1.37–1.44 (m, 2H), 1.54–1.74 (m, 4H), 2.16–
2.25 (m, 2H), 3.10–3.17 (m, 2H), 7.18 (td, J ¼ 8:6, 2.3 Hz,
4H), 7.38 (dt, J ¼ 8:6, 2.3 Hz, 4H); 13C NMR (67.8 MHz, CDCl3)
ꢀ 23.7, 30.4, 50.2, 121.3, 131.9, 133.5, 134.0. Anal. Calcd for
C18H18Br2S2: C, 47.18; H, 3.96; S, 13.99%. Found: C, 47.39;
H, 4.00; S, 14.02%.
1
5
T. Kondo, S. Uenoyama, K. Fujita, and T. Mitsudo, J. Am.
Chem. Soc., 121, 482 (1999).
a) P. D. Clark, S. T. E. Mesher, and M. Parvez, Catal. Lett.,
trans-1,2-Bis(2-pyridyl)cyclohexane. Colorless oil; IR (neat)
2928, 1578, 1384, 1122, 756 cmꢃ1; 1H NMR (400 MHz, CDCl3) ꢀ
1.55–1.59 (m, 2H), 1.70–1.81 (m, 4H), 2.34–2.40 (m, 2H), 4.20–
4.26 (m, 2H), 6.95 (dd, J ¼ 7:6, 5.0 Hz, 2H), 7.22 (d, J ¼ 7:6 Hz,
2H), 7.45 (td, J ¼ 7:6, 1.4 Hz, 2H), 8.38 (dd, J ¼ 5:0, 1.4 Hz,
2H); 13C NMR (100 MHz, CDCl3) ꢀ 24.2, 31.5, 46.7, 119.3,
122.9, 135.8, 149.2, 158.8. Anal. Calcd for C16H18N2S2: C,
63.54; H, 6.00; S, 21.20%. Found: C, 63.73; H, 6.18; S, 20.99%.
6
47, 73 (1997). b) K-10 montmorillonite modified by the addition
of MnCl2 promoted the reactions of aromatic compounds with
organic disulfides: see: P. D. Clark, S. T. E. Mesher, A. Primak,
and H. Yao, Catal. Lett., 48, 79 (1997).
7
A most recent example: T. Nishimura, S. Ohtaka, K.
Hashimoto, T. Yamauchi, T. Hasegawa, K. Imanaka, J. Tateiwa,
H. Takeuchi, and S. Uemura, Bull. Chem. Soc. Jpn., 77, 1765
(2004); For reviews, see: J. Tateiwa and S. Uemura, J. Jpn. Pet.
Inst., 40, 329 (1997); T. Nishimura and S. Uemura, Shokubai,
45, 313 (2003).
trans-1,2-Bis(benzylthio)cyclohexane.
(neat) 2929, 1494, 1453, 1445, 1070, 699 cmꢃ1
Colorless oil; IR
1H NMR (270
;
MHz, CDCl3) ꢀ 1.26–1.64 (m, 6H), 2.06–2.14 (m, 2H), 2.69–
2.76 (m, 2H), 3.69 (s, 4H), 7.18–7.32 (m, 10H); 13C NMR (67.8
MHz, CDCl3) ꢀ 23.7, 30.8, 36.0, 47.4, 126.8, 128.3, 128.8,
138.3. Anal. Calcd for C20H24S2: C, 73.12; H, 7.36; S, 19.52%.
Found: C, 73.10; H, 7.35; S, 19.46%.
8
Stereochemistry of the new compounds was speculated
from the known compounds reported in Refs. 2–4.
J. Tateiwa, H. Horiuchi, K. Hashimoto, T. Yamauchi, and
S. Uemura, J. Org. Chem., 59, 5901 (1994).
9