Synthesis of vinyl sulfoxides using sulfinyl chlorides and olefins

Article abstract of DOI:10.3184/174751915X14304098020793

A general method for synthesis of vinyl sulfoxides, using sulfinyl chlorides and olefins as starting materials and DBU as an HCl scavenger, has been developed. Vinyl sulfoxides were obtained from the ZnCl₂ catalysed addition of sulfinyl chlorides to olefins followed by the elimination with DBU. However, the direct reaction of sulfinyl chlorides with olefins in the presence of DBU, usually leads to generation of vinyl sulfones. The sulfonyl radicals generated from the DBU-mediated disproportionation of the sulfinyl radicals undergo addition-elimination reaction with olefins to give vinyl sulfones.

Full text of DOI:10.3184/174751915X14304098020793

282 RESEARCH PAPER
VOL. 39 MAY, 282–285
JOURNAL OF CHEMICAL RESEARCH 2015
Synthesis of vinyl sulfoxides using sulfinyl chlorides and olefins
Xiancai Dinga, Jianming Wenb, Jianqiang Wanga, Jun Yua and Jing-Hua Lia*
aCollege of Pharmaceutical Sciences, Zhejiang University of Technology, Zhaohui Liuqu 310032, Hangzhou, P.R. China
bHangzhou Allsino Chemicals Co., Ltd, Xihu Gyeyuan, 310000 Hangzhou, P.R. China
A general method for synthesis of vinyl sulfoxides, using sulfinyl chlorides and olefins as starting materials and DBU as an HCl scavenger,
has been developed. Vinyl sulfoxides were obtained from the ZnCl2 catalysed addition of sulfinyl chlorides to olefins followed by the
elimination with DBU. However, the direct reaction of sulfinyl chlorides with olefins in the presence of DBU, usually leads to generation
of vinyl sulfones. The sulfonyl radicals generated from the DBU-mediated disproportionation of the sulfinyl radicals undergo addition-
elimination reaction with olefins to give vinyl sulfones.
Keywords: vinyl sulfoxide, vinyl sulfone, DBU, olefin, sulfinyl chloride
Vinyl sulfoxides are useful building blocks in the synthesis
of biologically active compounds.1 There have been several
methods for the synthesis of vinyl sulfoxides including the Wittig
reaction,2-3 the Horner–Wadsworth–Emmons reaction,4 the
Andersen reaction,5 reduction of alkynyl sulfoxides,6 oxidation of
vinyl sulfides.7 and addition–oxidation of thiols with alkynes.8
We now report an approach to vinyl sulfoxides using sulfinyl
chlorides9-12 and olefins as starting materials.
In addition, an alternative method for the preparation of
vinyl sulfones was provided by reaction of olefins with sulfinyl
chlorides. The results are summarised in Table 2.
Table 1 Synthesis of vinyl sulfoxides from sulfinyl chlorides and olefinsa
O
O
rt
ZnCl Et
,
2
1,
2O,
reflux
S
+
R1
Ar
S
Cl
Ar
R1
2, DBU, Toluene,
:
2a Ar=Ph
4
1
:
2b Ar=
Tol
p-
Inourinitialwork, thereactionofstyrene1a withbenzenesulfinyl
chloride 2a did not occur. When DBU (1,8-diazabicyclo[5.4.0]
undec-7-ene) was added to the reaction mixture, however,
the reaction did occur. The isolated product was identified by
spectroscopy as [2-(phenylsulfonyl)vinyl]benzene (3a) instead
of the targetted product, [2-(phenylsulfinyl)vinyl]benzene (4a).
However, 4a could be obtained by the reaction of styrene (1a) with
benzenesulfinyl chloride (2a) in the presence of ZnCl2 followed by
the treatment with DBU (Scheme 1). Inspired by these preliminary
findings, we investigated the optimal conditions of this protocol
for the synthesis of vinyl sulfoxides and vinyl sulfones. Firstly, a
series of bases (e.g., DBU, Et3N, DABCO (1,4-diazabicyclo[2.2.2]
octane), pyridine, etc.) was screened. Among them, DBU was the
most effective, the other bases giving lower yields. Additionally, we
found that 1a and 2a did not react in the absence of base. Various
reaction conditions, such as solvents and temperature, were also
examined for the optimum. Thus, the standard conditions for the
synthesis of vinyl sulfoxides were established: treatment of the
mixture obtained by the reaction of olefins with sulfinyl chlorides
in the presence of ZnCl2 at room temperature, with DBU as a
scavenger in toluene under reflux produced vinyl sulfoxides. The
intermediate saturated sulfoxide {4ab, [1-chloro-2-(phenylsulfinyl)
ethyl]benzene} could be isolated from the reaction. This indicates
that the reaction proceeds by ZnCl2-catalysed addition of sulfinyl
chlorides to olefins followed by elimination with DBU to form
vinyl sulfoxides.
Entry
Product 4
Yield/%b
67
85
76
70
46
71
72
63
1
2
3
4
5
6
7
8
4a, R1 = C6H5, Ar=Ph
4b, R1 = p-CH3C6H4, Ar=Ph
4c, R1 = m-CH3OC6H4, Ar=Ph
4d, R1 =m-NO2C6H4, Ar=Ph
4e, R1 = C6H5, Ar=p-Tol
4f, R1 = p-CH3C6H4, Ar=p-Tol
4g, R1 = m-CH3OC6H4, Ar=p-Tol
4h, R1 =m-NO2C6H4, Ar=p-Tol
aStandard conditions: (1) olefin (1 mmol), sulfinyl chloride (1 mmol), ZnCl2 (1 mmol,
dissolved in 5 mL ethyl ether), solvent ethyl ether (5 mL) with a nitrogen balloon at room
temperature for 30–50 min; (2) DBU (1 mmol), solvent toluene (10 mL) at reflux for 5 h.
bIsolated yield, E major configuration mixed products except 4a and 4e.
Table 2 Synthesis of vinyl sulfones from sulfinyl chlorides and olefinsa
R2
R2
O
O
O
S
DBU
42 o
S
+
Ar
Cl
Ar
R1
R1
R3
C
THF,
R3
:
2a Ar=Ph
1
3
:
2b Ar=
Tol
p-
Entry
1
2
3
4
5
6
7
8
Product 3
3a, R1 = C6H5, R2 = R3 = H, Ar=Ph
Yield/%b
73
72
65
54
50
53
57
61
60
59
60
45
3b, R1 = p-CH3C6H4, R2 = R3 = H, Ar=Ph
3c, R1 = m-CH3OC6H4, R2 = R3 = H, Ar=Ph
3d, R1 = C6H5, R2 = CH3, R3 = H, Ar=Ph
3e, R1 = OCH2CH3, R2 = R3 =H, Ar=Ph
3f, R1 = O(CH2)3CH3, R2 = R3 =H, Ar=Ph
3g, R1, R3=-OCH2CH2-, R2 = H, Ar=Ph
3h, R1 = C6H5, R2 = R3 = H, Ar=p-Tol
3i, R1 = p-CH3C6H4, R2 = R3 = H, Ar=p-Tol
We investigated the scope of this protocol for the synthesis
of vinyl sulfoxides. The results are listed in Table 1. It was
discovered that a wide range of styrene derivatives can react to
provide the corresponding vinyl sulfoxides in good yields (Table
1).
O
O
S
DBU
42 o
9
+
PhSSPh
10
11
12
13
14
3j, R1 = m-CH3OC6H4, R2 = R3 = H, Ar=p-Tol
3k, R1 = C6H5, R2 = CH3, R3 = H, Ar=p-Tol
3l, R1 = OCH2CH3, R2 = R3 =H, Ar=p-Tol
3m, R1 = O(CH2)3CH3, R2 = R3 =H, Ar=p-Tol
3n, R1, R3= -OCH2CH2-, R2 = H, Ar=p-Tol
C
3a
THF,
5a
O
S
Cl
+
O
S
rt
ZnCl , Et
1a
2a
1,
2O,
2
48
2, DBU, Toluene,
reflux
4a
40
Scheme 1 Synthesis of vinyl sulfones and vinyl sulfoxides.
* Correspondent. E-mail: lijh@zjut.edu.cn
a Standard conditions: olefin (1 mmol), sulfinyl chloride (2 mmol, dissolved in 2 mL THF),
DBU (1.5 mmol), solvent THF (5 mL) at 42 oC for 3–8 h.
b Isolated yields based on 1.

JOURNAL OF CHEMICAL RESEARCH 2015 283
1
or Agilent 6210 LC/TOF instrument. H and 13C NMR spectra were
O
S
O
O
S
O
Cl
O
S
-HCl
obtained in CDCl3 on a Bruker Spectrospin 500 MHz or 400 MHz
spectrometer using TMS as internal standard.
Ph
Cl
Ph
Ph
Ph
Ph
Ph
2a
3a
3ab
Vinyl sulfones 3a–n; general procedure
Sulfinyl chloride 2 (2 mmol) in THF (2 mL) was added dropwise to a
stirred solution of olefin 1 (1 mmol) and DBU (1.5 mmol) in THF (5
mL) . The resulting mixture was stirred at 42 oC until the reaction was
completed as monitored by TLC (3:1 ethyl acetate/petroleum ether as
eluent). Water was added to the reaction system, and the mixture was
extracted with ethyl acetate (3×10 mL). The combined organic layers
were washed with dilute aqueous HCl (15 mL) and saturated NaCl
solution (15 mL), dried over MgSO4 and filtered. After removal of
the solvent under reduced pressure, the crude product was purified by
column chromatography (10:1 ethyl acetate/petroleum ether as eluent).
(E)-[2-(Phenylsulfonyl)vinyl]benzene (3a): White solid, m.p. 74–76
oC (lit.17 68–70 oC). 1H NMR (500 MHz, CDCl3): δ 7.98–7.96 (m, 2H),
7.70 (d, J = 15.4 Hz, 1H), 7.64–7.61 (m, 1H), 7.57–7.38 (m, 7 H), 6.89 (d, J
= 15.4 Hz, 1H) ppm. 13C NMR (100 MHz, CDCl3): δ 142.3, 140.4, 133.2,
132.1, 131.0, 129.1, 128.9, 128.4, 127.4, 127.0 ppm. MS (EI): m/z 244 (5)
[M+], 179 (60), 119 (74), 102 (46), 91 (100), 77 (40), 65 (22), 51 (49).
(E)-1-Methyl-4-[2-(phenylsulfonyl)vinyl]benzene (3b): White
solid, m.p. 136–138 oC (lit.17 130–132 oC). 1H NMR (500 MHz,
CDCl3): δ 7.97–7.95 (m, 2H), 7.68 (d, J = 15.0 Hz, 1H), 7.64–7.39 (m,
5H), 7.22–7.20 (m, 2H), 6.82 (d, J = 15.0 Hz, 1H), 2.39 (s, 3H) ppm.
13C NMR (100 MHz, CDCl3): δ 142.3, 141.6, 133.0, 129.6, 129.1, 128.4,
127.4, 126.4, 126.0, 125.1, 21.6 ppm.
Cl
O
S
O
O
O
Ph
Ph
Ph
S
S
2a
Cl
3aa
O
S
Ph-S-S-Ph
Ph-S
Ph
1a
Ph
5a
O
Scheme 2 Proposed mechanism for the formation of vinyl sulfones.
It was discovered that a wide range of olefins could form
vinyl sulfones in moderate yields. Aromatic alkenes bearing
substituents such as methyl or methoxy on the ring, underwent
the reaction to provide the corresponding vinyl sulfones in
good yields (Table 2, entries 1–3, 8–11). Moderate yields were
observed for styrene bearing an α-alkyl substituent (Table 2,
entries 4, 11). However, attempted synthesis of vinyl sulfones
using aliphatic alkenes gave unsatisfactory results under the
standard conditions (Table 2, entries 5–7, 12–14).
Although the exact mechanism of the conversion of
sulfinyl chlorides to sulfones (Scheme 2) is still not clear,
some information has been gathered. When TEMPO
(2,2,6,6-tetramethyl-1-piperidinyloxy, a well-known radical-
capturing species) was added to the reaction system, the
sulfonylation reaction was completely suppressed. This
indicates presumably that the reaction presumably involves a
radical process. Besides, it is noteworthy that no vinyl sulfoxide
product was observed. Under the standard conditions, the
reaction of 1a with 2a produced 3a with 0.5 equiv. 5a as the
side product (Scheme 1). Moreover, the anaerobic reaction
also generates vinyl sulfone 3a instead of vinyl sulfoxide 4a.
These results might indicate that sulfonyl free radicals are
produced from the disproportionation reaction of sulfinyl free
radicals, which, meanwhile, generates an equivalent amount
1-Methoxy-3-[2-(phenylsulfonyl)vinyl]benzene (3c): E/Z = 92/8,
o
o
1
white solid, m.p. 120–122 C (lit.18 115–117 C). H NMR (500 MHz,
CDCl3): δ 7.97–7.96 (m, 2H), 7.68–7.55 (m, 4H), 7.33–7.30 (m, 1H),
7.10–7.08 (m, 1H), 7.00–6.96 (m, 2H), 6.87 (d, J = 15.4 Hz, 1H), 3.82
(s, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ 159.7, 142.2, 140.4, 133.2,
129.9, 129.2, 128.5, 127.5, 127.3, 121.1, 117.0, 113.2, 55.4 ppm.
(E)-[(2-Phenylprop-1-en-1-yl)sulfonyl]benzene
(3d): White
o
o
1
solid, m.p. 72–74 C (lit.19 71–73 C). H NMR (500 MHz, CDCl3): δ
8.00–7.98 (m, 2H), 7.59–7.38 (m, 8H), 6.63 (s, 1H), 2.56 (s, 3H) ppm.
13C NMR (100 MHz, CDCl3): δ 153.3, 141.9, 139.8, 133.0, 129.7, 129.0,
128.5, 127.1, 127.0, 126.1, 17.3 ppm.
(E)-[(2-Ethoxyvinyl)sulfonyl]benzene (3e):20 Pale yellow oil.
1H NMR (500 MHz, CDCl3): δ 7.89–7.88 (m, 2H), 7.61–7.57 (m, 2H),
7.54–7.51 (m, 2H), 5.69 (d, J = 12.3 Hz, 1H), 3.91 (q, J = 7.1 Hz, 1H),
1.35 (t, J = 7.1 Hz, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ 160.5,
142.3, 132.6, 128.9, 126.7, 106.3, 67.6, 14.4 ppm.
of Ph-S. (Scheme 2). This is supported by previous literature
13-15
reports.11,
On the basis of the above observations, we
(E)-[(2-Butoxyvinyl)sulfonyl]benzene (3f):21: White solid, m.p.
42–45 °C. 1H NMR (400 MHz, CDCl3): δ 7.87–7.85 (m, 2H), 7.56–7.25
(m, 4H), 5.68 (d, J = 12.4 Hz, 1H), 3.82 (t, J = 6.0 Hz, 2H), 1.71–1.64
(m, 2H), 1.44–1.34 (m, 2H), 0.92 (t, J = 7.2 Hz, 2H) ppm. 13C NMR
(100 MHz, CDCl3): δ 189.4, 134.5, 129.5, 128.8, 127.9, 127.8, 66.7, 31.4,
19.2, 13.9 ppm.
4-(Phenylsulfonyl)-2,3-dihydrofuran (3g): White solid, m.p. 78–80
oC (lit.22 77–80 oC). 1H NMR (500 MHz, CDCl3): δ 7.91–7.90 (m, 2H),
7.64–7.54 (m, 3H), 7.24 (s, 1H), 4.62 (t, J = 10.0 Hz, 2H), 2.81 (t, J =
10.0 Hz, 2H) ppm. 13C NMR (100 MHz, CDCl3): δ 137.5, 133.9, 129.2,
128.5, 98.6, 69.9, 67.1, 25.8 ppm.
(E)-1-Methyl-4-(styrylsulfonyl)benzene (3h): White solid, m.p.
118–120 oC (lit.8 118–119 oC). 1H NMR (500 MHz, CDCl3): δ 7.85–7.83
(m, 2H), 7.67 (d, J = 15.4 Hz, 1H), 7.50–7.49 (m, 2H), 7.48-7.35 (m,
5H), 6.86 (d, J = 15.4 Hz, 1H), 2.45 (s, 3H) ppm. 13C NMR (100 MHz,
CDCl3): δ 144.2, 141.8, 137.5, 132.3, 130.9, 129.8, 128.9, 128.4, 127.6,
127.4, 21.7 ppm.
propose that a plausible mechanism (Scheme 2) consists of (i)
disproportionation of sulfoxide free radicals to produce Ph–SO2
.
and Ph–S free radicals.; (ii) electrophilic attack of the sulfonyl
radical on the electron-rich styrene to generate a benzylic
radical (3aa), which is trapped by Cl derived from the sulfinyl
chloride; (iii) elimination of a molecule of hydrogen chloride
from 3ab to afford the corresponding vinyl sulfones
(3a) in the presence of DBU. The side product PhSSPh,
meanwhile, is obtained from the coupling of the reactive
Ph–S. with another Ph–S.. 13,16
In conclusion, we have demonstrated an alternative
methodology for the preparation of substituted vinyl sulfoxides
and vinyl sulfones. In view of the experimental simplicity and
the mild reaction conditions, it is likely that this procedure will
find various applications in organic synthesis.
Experimental
1-Methyl-4-(4-methylstyrylsulfonyl)benzene (3i): E/Z = 71/29, white
solid, m.p. 149–154 oC (lit.17 152–155 oC). 1H NMR (500 MHz, CDCl3):
δ 7.84–7.83 (m, 2H), 7.64 (d, J = 15.4 Hz, 1H), 7.38–7.19 (m, 6 H), 6.81
(d, J = 15.4 Hz, 1H), 2.44 (s, 3H), 2.37 (s, 3H) ppm. 13C NMR (100
MHz, CDCl3): δ 144.0, 141.8, 141.5, 137.7, 130.5, 129.7, 129.6, 128.3,
127.4, 126.2, 21.7, 21.6 ppm.
Commercially available reagents were used without further
purification unless mentioned. All reactions were monitored by TLC.
Visualisation of TLC plates was accomplished with a UV lamp. The
column chromatography was performed using silica gel (200–300
o
mesh) with ethyl acetate/petroleum ether (b.p. 60–90 C) as eluent.
Melting points were recorded on a X-4 micro melting point apparatus.
LRMS-EI and HRMS-ESI were recorded on ThermoFisher ITQ1100
1-Methoxy-3-(2-tosylvinyl)benzene (3j):8 E/Z = 94/6, colourless oil.
1H NMR (500 MHz, CDCl3): δ 7.83–7.82 (m, 2H), 7.62 (d, J = 15.4 Hz,

284 JOURNAL OF CHEMICAL RESEARCH 2015
1
1H), 7.34–7.26 (m, 3H), 7.06–7.05 (m, 1H), 6.98–6.93 (m, 2H), 6.87 (d,
J = 15.4 Hz, 1H), 3.79 (s, 3H), 2.42 (s, 3H) ppm. 13C NMR (100 MHz,
CDCl3): δ 159.5, 144.0, 141.5, 137.3, 133.3, 129.7, 129.6, 127.5, 127.3,
120.8, 116.7, 113.0, 55.1, 21.5 ppm.
(Z)-[2-(Phenylsulfinyl)vinyl]benzene (4a):27 Pale yellow oil. H NMR
(500 MHz, CDCl3): δ 7.69–7.67 (m, 2H), 7.62–7.60 (m, 2H), 7.55–7.41 (m,
6 H), 7.14 (d, J = 10.6 Hz, 1H), 6.46 (d, J = 10.6 Hz, 1H) ppm. 13C NMR
(100 MHz, CDCl3): δ 144.2, 138.8, 136.4, 133.5, 130.7, 129.6, 129.4, 129.2,
128.5, 124.1 ppm. MS (EI): m/z 229 (4) [M++1], 199 (60), 180 (100), 179
(76), 165 (44), 91 (34), 77 (25), 65 (13), 51 (36).
(E)-1-Methyl-4-[2-(phenylsulfinyl)vinyl]benzene (4b):28 Colourless
oil. 1H NMR (500 MHz, CDCl3): δ 7.70–7.67 (m, 2H), 7.53–7.47 (m, 3H),
7.37–7.34 (m, 3H), 7.18–7.16 (m, 2H), 6.79 (d, J = 15.6 Hz, 1H), 3.35 (s,
3H) ppm. 13C NMR (100 MHz, CDCl3): δ 143.8, 140.0, 136.6, 131.5, 130.8,
130.6, 129.3, 129.1, 127.5, 124.4, 21.4 ppm.
(E)-1-Methoxy-3-[2-(phenylsulfinyl)vinyl]benzene (4c):28 Colourless
oil. 1H NMR (500 MHz, CDCl3): δ 7.64–7.63 (m, 2H), 7.46–7.41 (m, 3H),
7.30 (d, J = 15.5 Hz, 1H), 7.22–7.18 (m, 1H), 7.22–7.19 (m, 1H), 6.99–6.80
(m, 4H), 3.71 (s, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ 159.1, 143.1,
135.4, 134.3, 132.5, 130.5, 129.2, 128.8, 124.0, 119.7, 114.9, 112.3, 54.7
ppm.
(E)-1-Methyl-4-[(2-phenylprop-1-en-1-yl)sulfonyl]benzene
(3k):
White solid, m.p. 101–103 oC (lit.23 102–103 oC). 1H NMR (500 MHz,
CDCl3): δ 7.88–7.86 (m, 2H), 7.42–7.35 (m, 7H), 6.61 (s, 1H), 2.53 (s,
3H), 2.45 (s, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ 153.0, 144.2,
140.3, 139.3, 130.0, 129.5, 128.8, 127.9, 127.4, 126.4, 22.0, 17.5 ppm.
(E)-1-[(2-Ethoxyvinyl)sulfonyl]-4-methylbenzene
(3l):
White
solid, m.p. 57–59 C (lit.24 57–58 C). H NMR (500 MHz, CDCl3): δ
7.75–7.74 (m, 2H), 7.56 (d, J = 12.3 Hz, 1H), 7.31–7.28 (m, 2H), 5.67
(d, J = 12.3 Hz, 1H), 3.88 (q, J = 7.1 Hz, 1H), 2.41 (s, 3H), 1.32 (t, J =
7.1 Hz, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ 160.0, 143.3, 139.4,
129.5, 126.7, 106.7, 67.5, 21.6, 14.4 ppm.
o
o
1
(E)-1-[(2-Butoxyvinyl)sulfonyl]-4-methylbenzene (3m): White
1
solid, m.p. 39–42 °C. H NMR (500 MHz, CDCl3): δ 7.78–7.76 (m,
2H), 7.59 (d, J = 12.2 Hz, 1H), 7.33–7.31 (m, 2H), 5.68 (d, J = 12.2 Hz,
1H), 3.82 (t, J = 6.6 Hz, 2H), 2.44 (s, 1H), 1.71–1.65 (m, 2H), 1.44–1.36
(m, 2H), 0.94 (t, J = 7.4 Hz, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ
189.3, 129.8, 129.1, 127.7, 127.6, 127.5, 66.6, 31.3, 21.5, 19.0, 13.6 ppm.
HRMS (ESI) calcd for C13H19O3S [M+H]+: 255.1049; found: 255.1067.
1-Nitro-3-[2-(phenylsulfinyl)vinyl]benzene (4d): E/Z = 90/10, pale
yellow oil. 1H NMR (500 MHz, CDCl3): δ 8.29–8.28 (m, 1H), 8.17–8.15
(m, 1H), 7.75–7.68 (m, 3H) , 7.57–7.51 (d, 3H), 7.41 (d, J = 15.4 Hz, 1H),
7.02 (d, J = 15.4 Hz, 1H) ppm. 13C NMR (150 MHz, CDCl3): δ 148.6, 143.1,
136.5, 135.5, 133.5, 132.3, 131.5, 129.9, 129.6, 124.7, 123.9, 121.9 ppm.
o
4-Tosyl-2,3-dihydrofuran (3n): White solid, m.p. 106–108 C (lit.25
HRMS (ESI) calcd for C14H12NO3S [M]+, 274.0532; found: 274.0533.
106–107 oC). 1H NMR (500 MHz, CDCl3): δ 7.79–7.77 (m, 2H),
7.35–7.34 (m, 2H), 7.21 (s, 1H), 4.61 (t, J = 9.6 Hz, 2H), 2.82–2.78 (m,
2H), 2.45 (s, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ 145.0, 134.5,
129.8, 128.6, 98.6, 70.1, 67.0, 25.9, 21.8 ppm.
29
(Z)-1-Methyl-4-(styrylsulfinyl)benzene (4e):8,
Pale yellow oil.
1H NMR (500 MHz, CDCl3): δ 7.59–7.57 (m, 4H), 7.47–7.40 (m, 3H),
7.34–7.32 (m, 2H), 7.11 (d, J = 10.6 Hz, 1H), 6.45 (d, J = 10.6 Hz, 1H), 2.42
(s, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ 141.2, 141.1, 138.3, 136.7,
133.6, 129.9, 129.6, 129.3, 128.5, 124.2, 21.5 ppm.
Sulfone reaction from which diphenyl disulfide was isolated
1-Methyl-4-(4-methylstyrylsulfinyl)benzene (4f):8 E/Z
=
93/7,
Benzenesulfinyl chloride 2a (2 mmol) in THF (2 mL) was added
dropwise to a stirred solution of styrene 1a (1 mmol) and DBU (1.5
mmol) in THF (5 mL) The resulting mixture was stirred at 42 oC until
the reaction was completed as monitored by TLC (3:1 ethyl acetate/
petroleum ether as eluent). Water was added to reaction system and the
mixture was extracted with ethyl acetate (3×10 mL). The combined
organic layers were washed with diluted aqueous HCl (15 mL) and
saturated NaCl solution (15 mL), dried over MgSO4 and filtered. After
removal of the solvent under reduced pressure, the crude product was
purified by column chromatography (10:1 ethyl acetate/petroleum
ether as eluent) to provide diphenyl disulfide 5a (0.080 g, 0.37 mmol)
and (E)-[2-(phenylsulfonyl)vinyl]benzene 3a (0.178 g, 0.73 mmol).
colourless oil. 1H NMR (500 MHz, CDCl3): δ 7.58–7.56 (m, 2H),
7.34–7.28 (m, 5H), 7.16–7.14 (m, 2H), 6.77 (d, J = 15.6 Hz, 1H), 2.39 (s,
3H), 2.34 (s, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ 141.2, 140.4, 139.6,
135.9, 131.5, 130.6, 129.7, 129.2, 127.3, 124.4, 21.3 ppm.
(E)-1-Methoxy-3-[2-(p-tolylsulfinyl)vinyl]benzene (4g):8 Pale yellow
oil. 1H NMR (500 MHz, CDCl3): δ 7.48–7.47 (m, 2H), 7.22 (d, J = 15.5 Hz,
1H), 7.19–7.17 (m, 2H), 7.15–7.12 (m, 1H), 6.92–6.87 (m, 2H), 6.78–6.75
(m, 2H), 3.64 (s, 3H), 2.25 (s, 3H) ppm. 13C NMR (150 MHz, CDCl3): δ
159.1, 140.6, 140.2, 134.5, 134.4, 133.0, 129.2, 129.0, 123.9, 119.4, 114.6,
112.1, 54.3, 20.4 ppm.
1-Nitro-3-[2-(p-tolylsulfinyl)vinyl]benzene (4h): E/Z = 98/2, pale
yellow oil. 1H NMR (500 MHz, CDCl3): δ 8.29–8.28 (m, 1H), 8.17–8.15
(m, 1H), 7.75–7.74 (d, J = 7.8 Hz, 1H), 7.58–7.53 (m, 3H) , 7.41–7.33 (d,
3H), 7.00 (d, J = 15.4 Hz, 1H), 2.41 (s, 3H) ppm. 13C NMR (150 MHz,
CDCl3): δ 148.6, 142.2, 139.9, 136.7, 135.6, 133.5, 132.0, 130.3, 129.9,
124.9, 124.5, 123.8, 121.9, 21.3 ppm. HRMS (ESI) calcd for C15H14NO3S
[M+H]+:288.0689; found: 288.0699.
Diphenyl disulfide (5a): White solid, m.p. 58–60 C (lit.26 59 C).
1H NMR (500 MHz, CDCl3): δ 7.53–7.52 (d, 4H), 7.33–7.31 (t, 4H),
7.27–7.24 (t, 2H) ppm. 13C NMR (150 MHz, CDCl3): δ 137.2, 129.2,
127.7, 127.3 ppm.
o
o
Reaction in the presence of TEMPO
Benzenesulfinyl chloride 2a (2 mmol) in THF (2 mL) was added
dropwise to a stirred solution of styrene 1a (1 mmol), DBU (1.5 mmol)
and TEMPO (0.15 mmol) in THF (5 mL) . The resulting mixture was
stirred at 42 oC for 3 h, from which no product 3a was isolated. It was
shown that the sulfonylation reaction was completely suppressed,
monitored by TLC.
Synthesis of 4ab; general procedure
Anhydrous ZnCl2 (1 mmol) dissolved in anhydrous ethyl ether (5
mL) was added to a stirred solution of styrene 1a (1 mmol) and
benzenesulfinyl chloride 2a (1 mmol) in anhydrous ethyl ether (5 mL).
The resulting mixture was stirred at room temperature with a nitrogen
balloon for 30 min. Water was added to the reaction system and the
mixture was extracted with ethyl acetate (3×10 mL). The combined
organic layers were washed with diluted aqueous HCl (15 mL) and
saturated NaCl solution (15 mL), dried over MgSO4 and filtered. After
removal of the solvent under reduced pressure, the crude product was
purified by column chromatography (5:1 ethyl acetate/petroleum
ether as eluent) provide the product 4ab (0.216 g) in 82% yield.
[1-Chloro-2-(phenylsulfinyl)ethyl]benzene (4ab): White solid, m.p.
80–82 oC (lit.30 84–85 oC). 1H NMR (500 MHz, CDCl3): δ 7.69–7.64 (m,
2H), 7.56–7.52 (m, 3H), 7.49–7.40 (m, 4H), 7.40–7.32 (m, 1H), 5.46–5.18
(m, 1H), 3.71–3.26 (m, 2H) ppm.
Vinyl sulfoxides 4a–h; general procedure
Anhydrous ZnCl2 (1 mmol) dissolved in anhydrous ethyl ether (5 mL)
was added to a stirred solution of olefin 1 (1 mmol) and sulfinyl chloride
2 (1 mmol) in anhydrous ethyl ether (5 mL) . The resulting mixture was
stirred at room temperature with a nitrogen balloon for 30–50 min. The
whole mixture was poured into a mixture of ice water (5 g) and toluene
(10 mL) and separated. The organic layer, after addition of DBU (1
mmol), was refluxed to eliminate hydrogen chloride completely as
monitored by TLC (2:1 ethyl acetate/petroleum ether as eluent). Water
was added to the reaction system and the mixture was extracted with
ethyl acetate (3×10 mL). The combined organic layers were washed with
diluted aqueous HCl (15 mL) and saturated NaCl solution (15 mL), dried
over MgSO4 and filtered. After removal of the solvent under reduced
pressure, the crude product was purified by column chromatography (6:1
ethyl acetate/petroleum ether as eluent).
Electronic Supplementary Information
The 1H and 13C NMR and mass spectra of the products have been
deposited in the ESI available through stl.publisher.ingentaconnect.
com/content/stl/jcr/supp-data.

JOURNAL OF CHEMICAL RESEARCH 2015 285
15 G. W. Kabalka, M. S. Reddy and M.-L. Yao, Tetrahedron Lett., 2009, 50,
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