Total stereochemical control in the addition of thiols to p-toluenesulfonylacetylene. Synthesis of Z-and E-2-sulfanylvinylsulfonyl derivatives

Article abstract of DOI:10.1021/jo0402576

(Chemical Equation Presented) Alkyl and aryl sulfides react with equimolecular amounts of p-toluenesulfonylacetylene in CH₃CN at 0°C or rt without the use of any catalytic reagent to give good yields of Z-2-sulfanylvinylsulfonyl derivatives wit

Full text of DOI:10.1021/jo0402576

SCHEME 1
Total Stereochemical Control in the
Addition of Thiols to
p-Toluenesulfonylacetylene. Synthesis of Z-
and E-2-Sulfanylvinylsulfonyl Derivatives
no precedent in the literature.4 Thus, considering the
interesting functionality present in vinyl sulfones such
as 2 we decided to optimize this uncatalyzed addition
with respect to stereoselectivity, economical ratio of
reagents, as well as reaction conditions.
Roc´ıo Medel, Mar´ıa I. Monterde, Joaqu´ın Plumet,* and
Jenny K. Rojas
Departamento de Quı´mica Orga´nica I, Facultad de
Quı´mica, Universidad Complutense, 28040 Madrid, Spain
In addition, for both catalyzed and uncatalyzed addi-
tion, the “trans-rule” appears to be followed without
exception. Then, our second objective was a search of
experimental conditions in order to obtain the corre-
sponding E-isomer with a convenient stereoselectivity.
The description of how these two goals were achieved is
the subject of the present report.
plumety@quim.ucm.es
Received September 9, 2004
Results
Uncatalyzed Addition: Synthesis of Z-2-Sulfa-
nylvinyl Sulfone Derivatives Z-2. Assuming that the
most likely intermediate for this uncatalyzed addition
should be a zwitterionic species (Figure 1) stabilized by
the participation of the remote p-toluenesulfonyl group,5
the increase of the solvent polarity of the reaction
medium should also increase the reaction rate avoiding
the use of an excess of the reagent and shortening the
reaction time.6
Alkyl and aryl sulfides react with equimolecular amounts
of p-toluenesulfonylacetylene in CH3CN at 0 °C or rt without
the use of any catalytic reagent to give good yields of Z-2-
sulfanylvinylsulfonyl derivatives with total diastereoselec-
tivity. On the other hand, in the presence of 1.1 equiv of
NaH in THF, the same reaction affords the corresponding
E-diastereomer also with total diastereoselectivity.
The base-catalyzed addition of thiols to acetylenic
sulfones 1 to give the corresponding sulfanyl-substituted
vinyl sulfones 2 has been known for many years (Scheme
1).1
FIGURE 1. Assistance of the p-toluenesulfonyl group to a
remote positive center.
The application of this reaction as a new method for
the protection of the thiol group has recently been
reported.2 In all cases, this reaction follows the “trans-
rule”; i.e., trans addition of the RS and H moieties gives
the Z derivatives Z-2.
On the other hand, the participation of the arylsulfonyl
group should also secure the Z-stereochemistry of the
final product. Thus, we decided to carry out the reaction
in CH3CN as solvent. The results, compared with the use
of THF, are gathered in Table 1.
By comparison of the results in both solvents, we can
make the following conclusions. (i) For aliphatic thiols
(entries 1-7) the use of CH3CN allows for the synthesis
of the corresponding Z-diastereomers with high diaste-
reoselectivity, in short reaction times, and in excellent
In a previous paper,3 we have described the uncata-
lyzed addition of aromatic and aliphatic thiols to p-
toluenesulfonylacetylene to give variable yields of the
expected addition products mainly as Z-isomers. The best
conditions for this transformation were the use of an
excess of thiol which was always recovered in 90-100%
yield and, in general, long reaction times. In some cases,
reactions under reflux of CH2Cl2 were necessary in order
to obtain moderate to good isolated yields of the final
product.
(4) The UV-irradiation-induced addition of thiols to monosubstituted
propargilyc alcohols has been also reported. See: (a) Mantione, R.;
Normant, H. Bull. Soc. Chem. Fr. 1973, 2261-2265. For other
additions of thiols to alkynes under radical conditions, usually giving
stereoisomeric mixtures, see: (b) Kuniyasu, H.; Ogawa, A.; Sato, K.;
Ryu, I.; Kambe, N.; Sonoda, N. J. Am. Chem. Soc. 1992, 114, 5902-
5903. (c) Kuniyasu, H.; Ogawa, A.; Sato, K.; Ryu, I.; Sonoda, N.
Tetrahedron Lett. 1992, 33, 5525-5528. (d) Ogawa, A.; Kudo, A.; Hirao,
T. Tetrahedron Lett. 1998, 3, 5213-5216 and references therein. For
the uncatalyzed addition to methylpropiolate, see: (e) Kodomari, M.;
Saitoh, G.; Yoshitomi, S. Bull. Soc. Chem. Jpn. 1991, 64, 3485-3487.
(5) See, for instance: Lambert, J. B.; Beadle, B. M.; Kuang, K. J.
Org. Chem. 1999, 64, 9241-9246.
With the exception of this previous account, the un-
catalyzed addition of thiols to arylsulfonylacetylenes has
* To whom correspondence should be addressed. Tel: 0034913944100.
Fax: 0034913944100.
(1) See, for instance: (a) Stirling, C. J. M. J. Chem. Soc. 1964, 5856-
5862. (b) Truce, W. E.; Tichenor, G. J. W. J. Org. Chem. 1972, 37,
2391-2394. (c) Selling, H. A. Tetrahedron 1975, 31, 2387-2390.
(2) Arjona, O.; Medel, R.; Rojas, J. K.; Costa, A. M.; Vilarrasa, J.
Tetrahedron Lett. 2003, 44, 6369-6373.
(6) For instance, the rate constant for the reaction between piperi-
dine and methylpropiolate increases by a factor of 865 from cyclohexane
to acetonitrile. See: Giese, B.; Huisgen, R. Tetrahedron Lett. 1967,
1889-1892.
(3) Arjona, O.; Iradier, F.; Medel, R.; Plumet, J. J. Org. Chem. 1999,
64, 6090-6093.
10.1021/jo0402576 CCC: $30.25 © 2005 American Chemical Society
Published on Web 12/22/2004
J. Org. Chem. 2005, 70, 735-738
735

TABLE 1. Uncatalyzed Addition of Thiols to
SCHEME 3
p-Toluenesulfonylacetylenea
compd
(isolated
solvent time (h) (°C) yield, %)b ratioc
reaction
T
Z/E
entry
R
TABLE 2. NaH-Promoted Addition of Thiols to
1
2
Bn
CH3CN
THF
0.5
5
0
Z-2a (98) 100:0
p-Toluenesulfonylacetylenea
p-ClC6H4CH2
p-ClC6H4CH2
rtd Z-2b (70) 100:0
3
CH3CN
2
0
rt
0
rt
0
rt
0
rt
0
rt
0
Z-2b (92)
Z-2c (85)
Z-2c (100)
90:10
100:0
90:10
4
p-MeOC6H4CH2 THF
p-MeOC6H4CH2 CH3CN
CH3(CH2)6CH2 THF
CH3(CH2)6CH2 CH3CN
5
5
1
6
5
Z-2d (31) 100:0
Z-2d (100) 98:2
7
1.5
5
8
C6H5
C6H5
THF
CH3CN
THF
CH3CN
CH2Cl2
CH3CN
Z-2e (49)
Z-2e (99)
Z-2f (49)
Z-2f (63)
Z-2f (89)
100:0
100:0
100:0
100:0e
100:0
reaction
9
0.5
5
19
2
1
time
compd
Z/E
entry
R
(min)
T (°C) (isol yield, %)b
ratioc
10
11
p-NO2C6H4
p-NO2C6H4
1
2
3
4
5
6
7
Bn
20
20
0
E-2a (100)
E-2b (100)
E-2c (100)
E-2d (100)
E-2e (100)
Z-2f (100)
E-2g (40)
0:100
0:100
0:100
0:100
<2:>98
100:0
0:100
12f p-NO2C6H4
pClC6H4CH2
pMeOC6H4CH2
CH3(CH2)6CH2
C6H5
0
13
p-MeOC6H4
Z-2g (67) 100:0
20
0
0
a 1.1 equiv of 1 was used. b Isolated yields after purification of
reaction crude by column chromatography (hexanes-EtOAc, 10:
1). c Determined in the 1H NMR spectra of the crude residue
product. For the Z-isomer δH ) 6.16-6.43 and 6.92-7.26, J )
10.2-10.3 Hz. For the E-isomer data, see below. d rt means
between 20 and 23 °C. e A ratio of Z/E ) 95:5 was observed after
column chromatography. f 1.5 equiv of thiol was used.
20
90
0 to rtd
0 to rt
0 to rt
pNO2C6H4
PMeOC6H4
60
300
a All reactions were conducted in THF using 1.1 equiv of 1 and
in the presence of 1.1 equiv of NaH. b Isolated yields after
purification of reaction crude by column chromatography (hex-
anes-EtOAc, 10:1). c Determined in the 1H NMR spectra of the
crude residue product. For the E-isomer δH ) 5.83-7.24, 7.57-
7.80, J ) 14.2-14.7 Hz. d rt means 21.5-23 °C.
SCHEME 2
In a first approach the use of MeOH as solvent appears
not to be convenient because, in a control experiment,
the uncatalyzed addition of benzenethiol to sulfone 1 in
MeOH afforded a mixture of Z-2e and E-2e in 65%
isolated yield (ratio Z/E ) 4:1) together with the product
arising for a second addition of thiol 4 in 30% isolated
yield (Scheme 3).
However, when 1.1 equiv of NaH was used in THF,
excellent yields of the corresponding E-2 isomers were
obtained (Table 2) with the exception of compound 2f
(entry 6, Table 2). For this thiol and after 1 h (0 °C to rt)
only diastereomer Z-2f was obtained in quantitative
yield. In this case, an increase of temperature and/or
reaction time led to extensive decomposition of the
reaction crude. On the other hand, for compound E-2g,
excellent stereoselectivity albeit in low yield (40%) was
obtained (entry 7, Table 2).
yields. Particularly notorious is the effect of the change
of the solvent in the case of n-octanethiol (compare
entries 6 and 7, Table 1). Almost equimolecular amounts
of reagents were used in all cases (thiol/sulfone ratio )
1:1.1). (ii) For aromatic thiols with different electronic
demand we have observed in all cases an excellent
diastereoselectivity. In the case of the p-nitro derivative
(entries 10-12, Table 1), the best results were obtained
in CH2Cl2 using a slight excess of thiol (1.5:1) whereas
for the p-methoxybenzenethiol the adduct was obtained
only with acceptable yield (entry 13). It should be pointed
out that, for this compound, the best results using CH2-
Cl2 as solvent require the use of a 3:1 thiol/sulfone ratio.
In this case and after 7 days, a quantitative yield of the
vinyl sulfone was obtained but in diastereomeric ratio
Z/E ) 1.5:1.3
NaH-Promoted Addition: Synthesis of E-2-Sul-
fanylvinyl Sulfone Derivatives (E-2). To obtain the
corresponding E-isomers we turned our attention to an
old report of Truce and Heine7 in which the addition of
p-toluenethiol to propiolic acid in the presence of catalytic
amounts of EtONa in EtOH afforded the mixture of Z-
and E-alkenes 3. Thus, and at least partially, the “trans-
rule” has been violated (Scheme 2).
Conclusions
In summary, in this paper, convenient methods for the
stereoselective synthesis of Z- and E-2-sulfanylvinyl
sulfone derivatives have been described. Especially sig-
nificant is the development of an uncatalyzed procedure
for the synthesis of Z-isomers probably through a step-
wise, sulfone-assisted mechanism. The detailed mecha-
nism is currently under study in our laboratory. More-
over, given the importance of vinylsulfonyl and vinyl-
sulfanyl derivatives, the combination of both function-
alities in a single molecule offers new synthetic possibili-
ties which are currently under consideration.
Then we decided to use these strongly basic conditions
for the preparation of the corresponding E-2 derivatives.
Experimental Section
General Procedure for the Synthesis of Z-2-Sulfanyl-
vinyl Sulfone Derivatives (Z-2a-g). To a solution of p-
(7) Truce, W. E.; Heine, R. F. J. Am. Chem. Soc. 1957, 79, 5311-
5313.
736 J. Org. Chem., Vol. 70, No. 2, 2005

toluenesulfonylacetylene 1 (0.33 mmol) in 3 mL of CH3CN or
THF (see Table 1) was added the corresponding thiol (0.30
mmol). The mixture was stirred at the temperature and for the
time indicated in Table 1. The solvent was removed in vacuo
without heating. The ratio of isomers was determined in the 1H
NMR spectra of the crude residue product, and the crude residue
was sometimes purified (it was not always required) by column
chromatography on silica gel using a mixture of hexanes-EtOAc
(10:1) as eluant. Compounds Z-2e-g have been previously
described as thiosulfonylethylene derivatives.3
1-[[(Z)-2-(Benzylsulfanyl)vinyl]sulfonyl]-4-methylben-
zene, Z-2a. White solid. Mp: 109-110 °C. IR (KBr): ν 3090,
1590, 1350. 1H NMR (CDCl3, 200 MHz): δ 2.44 (s, 3 H), 3.96 (s,
2 H), 6.18 (d, 1 H, J ) 10.3 Hz), 6.98 (d, 1 H, J ) 10.3 Hz),
7.31-7.34 (m, 7 H), 7.84 (d, 2 H, J ) 8.30 Hz). 13C NMR (CDCl3,
50 MHz): δ 21.6, 39.3, 123.4, 127.2, 127.8, 128.9, 129.0, 129.7,
136.1, 138.5, 144.3, 144.6. Anal. Calcd for C16H16O2S2: C, 63.13;
H, 5.30. Found: C, 63.08; H, 5.40.
mmol) in THF (1.5 mL) at 0 °C, under Ar. The mixture was
stirred at the temperature and for the time indicated in Table
2. The reaction was quenched with phosphate buffer and
extracted with CH2Cl2. The organic extracts were collected and
dried over MgSO4, filtered, and concentrated under reduced
1
pressure. The ratio of isomers was determined in the H NMR
spectra of the crude residue product, and the crude reaction
product was sometimes purified (it was not always required) by
column chromatography on silica gel using a mixture of hex-
anes-EtOAc (10:1) as eluant. Compounds E-2e-g have been
previously described as thiosulfonylethylene derivatives.3
1-[[(E)-2-(Benzylsulfanyl)vinyl]sulfonyl]-4-methylben-
zene, E-2a. White solid. Mp: 115-116 °C. IR (KBr): ν 3090,
1583, 1297. 1H NMR (CDCl3, 200 MHz): δ 2.44 (s, 3 H), 3.99 (s,
2 H), 6.19 (d, 1 H, J ) 14.4 Hz), 7.23-7.33 (m, 7 H), 7.66-7.73
(m, 3 H). 13C NMR (CDCl3, 50 MHz): δ 21.5, 37.0, 122.9, 127.3,
128.0, 128.7, 128.9, 129.8, 134.6, 138.2, 144.0, 144.2. Anal. Calcd
for C16H16O2S2: C, 63.13; H, 5.30. Found: C, 63.19; H, 5.38.
1-Chloro-4-[[[(E)-2-[(4-methylphenyl)sulfonyl]vinyl]sul-
fanyl]methyl]benzene, E-2b. White solid. Mp: 131-132 °C.
IR (KBr): ν 2998, 1610, 1220. 1H NMR (CDCl3, 300 MHz): δ
2.45 (s, 3 H), 3.97 (s, 2 H), 6.17 (d, 1 H, J ) 14.7 Hz), 7.22-7.31
(m, 6 H), 7.63-7.70 (m, 3 H). 13C NMR (CDCl3, 50 MHz): δ 21.5,
36.2, 123.4, 127.3, 129.0, 129.8, 130.0, 133.1, 133.9, 138.0, 143.5,
144.0. Anal. Calcd for C16H15ClO2S2: C, 56.71; H, 4.46. Found:
C, 56.67; H, 4.40.
1-Chloro-4-[[[(Z)-2-[(4-methylphenyl)sulfonyl]vinyl]sul-
fanyl]methyl]benzene, Z-2b. White solid. Mp: 123-124 °C.
IR (KBr): ν 3100, 1630, 1150. 1H NMR (CDCl3, 300 MHz): δ
2.45 (s, 3 H), 3.91 (s, 2 H), 6.18 (d, 1 H, J ) 10.3 Hz), 6.92 (d, 1
H, J ) 10.3 Hz) 7.19-7.33 (m, 6 H), 7.82 (d, 2 H, J ) 8.0 Hz).
13C NMR (CDCl3, 50 MHz): δ 21.5, 38.6, 123.8, 127.1, 128.9,
129.6, 130.2, 133.6, 134.2, 138.2, 144.0, 144.7. Anal. Calcd for
C
16H15ClO2S2: C, 56.71; H, 4.46. Found: C, 56.68; H, 4.50.
1-Methoxy-4-[[[(Z)-2-[(4-methylphenyl)sulfonyl]vinyl]-
1-Methoxy-4-[[[(E)-2-[(4-methylphenyl)sulfonyl]vinyl]-
sulfanyl]methyl]benzene, Z-2c. White solid. Mp: 119-120 °C.
IR (KBr): ν 3080, 1615, 1310. 1H NMR (CDCl3, 200 MHz): δ
2.43 (s, 3 H), 3.79 (s, 3 H), 3.90 (s, 2 H), 6.16 (d, 1 H, J ) 10.3
Hz), 6.84 (d, 2 H, J ) 8.5 Hz), 6.93 (d, 1 H, J ) 10.3 Hz), 7.18-
7.32 (m, 4 H), 7.83 (d, 2 H, J ) 8.3 Hz). 13C NMR (CDCl3, 50
MHz): δ 21.6, 38.8, 55.3, 114.3, 123.2, 127.2, 128.0, 129.7, 130.3,
138.5, 144.3, 144.8, 159.2. Anal. Calcd for C17H18O3S2: C, 61.05;
H, 5.42. Found: C, 60.97; H, 5.48.
sulfanyl]methyl]benzene, E-2c. White solid. Mp: 125-126
1
°C. IR (KBr): ν 3090, 1590, 1310. H NMR (CDCl3, 200 MHz):
δ 2.42 (s, 3 H), 3.80 (s, 3 H), 3.95 (s, 2 H), 6.18 (d, 1 H, J ) 14.7
Hz), 6.85 (d, 2 H, J ) 8.5 Hz), 7.18-7.32 (m, 4 H), 7.64-7.72
(m, 3 H). 13C NMR (CDCl3, 50 MHz): δ 21.6, 36.5, 55.3, 114.3,
122.8, 126.4, 127.3, 129.8, 130.0, 138.3, 143.9, 144.4, 159.4. Anal.
Calcd for C17H18O3S2: C, 61.05; H, 5.42. Found: C, 61.12; H,
5.37.
1-Methyl-4-[[(Z)-2-(octylsulfanyl)vinyl]sulfonyl]ben-
zene, Z-2d. Pale yellow oil. IR (CHCl3): ν 1643, 1425, 1314. 1H
NMR (CDCl3, 200 MHz): δ 0.88 (t, 3 H, J ) 6.8 Hz) 1.25-1.39
(m, 10 H), 1.56-1.70 (m, 2 H), 2.43 (s, 3 H), 2.74 (t, 2 H, J ) 7.1
Hz), 6.20 (d, 1 H, J ) 10.3 Hz), 7.03 (d, 1 H, J ) 10.3 Hz), 7.32
(dd, 2 H, J ) 8.3, 0.7 Hz), 7.86 (d, 2 H, J ) 8.3 Hz). 13C NMR
(CDCl3, 50 MHz): δ 13.9, 21.5, 22.5, 28.1, 28.9, 29.9, 31.6, 36.1,
122.6, 127.1, 129.5, 138.6, 144.1, 146.7. Anal. Calcd for
1-Methyl-4-[[(E)-2-(octylsulfanyl)vinyl]sulfonyl]ben-
1
zene, E-2d. Pale yellow oil. IR (CHCl3): ν 1643,1410,1260. H
NMR (CDCl3, 200 MHz): δ 0.89 (t, 3 H, J ) 6.8 Hz) 1.26-1.42
(m, 10 H), 1.58-1.73 (m, 2 H), 2.44 (s, 3 H), 2.76 (t, 2 H, J ) 7.1
Hz), 6.12 (d, 1 H, J ) 14.6 Hz), 7.33 (d, 2 H, J ) 8.5 Hz), 7.71
(d, 1 H, J ) 14.6 Hz), 7.76 (d, 2 H, J ) 8.3 Hz). 13C NMR (CDCl3,
50 MHz): δ 14.0, 21.5, 22.6, 28.3, 28.7, 29.0, 31.7, 32.4, 121.9,
127.3, 129.8, 138.4, 143.9, 145.4. Anal. Calcd for C17H26O2S2: C,
62.57; H, 7.97. Found: C, 62.50; H, 7.91.
C17H26O2S2: C, 62.57; H, 7.97. Found: C, 62.51; H, 8.05.
1-Methyl-4-[[(Z)-2-(phenylsulfanyl)vinyl]sulfonyl]-
1-Methyl-4-[[(E)-2-(phenylsulfanyl)vinyl]sulfonyl]-
benzene, E-2e. White solid. Mp: 91-92 °C. IR (KBr): ν 3069,
1493, 1277. 1H NMR (CDCl3, 200 MHz): δ 2.43 (s, 3 H), 5.99 (d,
1 H, J ) 14.4 Hz), 7.31 (d, 2 H, J ) 8.5 Hz), 7.41-7.46 (m, 5 H),
7.71 (d, 2 H, J ) 8.3 Hz), 7.80 (d, 1 H, J ) 14.4 Hz). 13C NMR
(CDCl3, 75 MHz): δ 21.6, 123.5, 127.4, 127.5, 129.8, 129.9, 133.3,
133.4, 135.4, 144.1, 145.6. Anal. Calcd for C15H14O2S2: C, 62.07;
H, 4.83. Found: C, 62.15; H, 4.70.
benzene, Z-2e. White solid. Mp 107-108 °C. IR (KBr): ν 3045,
1319, 1290. 1H NMR (CDCl3, 300 MHz): δ 2.45 (s, 3 H), 6.26 (d,
1 H, J ) 10.3 Hz), 7.22 (d, 1 H, J ) 10.3 Hz), 7.34-7.40 (m, 5
H), 7.42-7.47 (m, 2 H), 7.92 (d, 2 H, J ) 8.3 Hz). 13C NMR
(CDCl3, 50 MHz): δ 21.6, 122.9, 127.2, 128.7, 129.5, 129.8, 131.2,
134.6, 138.3, 144.5, 146.1. Anal. Calcd for C15H14O2S2: C, 62.07;
H, 4.83. Found: C, 62.12; H, 4.66.
1-Methyl-4-[[(Z)-2-[(4-nitrophenyl)sulfanyl]vinyl]sulfonyl]-
benzene, Z-2f. White solid. Mp: 152-153 °C. IR (KBr): ν 3651,
1545, 1342. 1H NMR (CDCl3, 200 MHz): δ 2.46 (s, 3 H), 6.43 (d,
1 H, J ) 10.2 Hz), 7.26 (d, 1 H, J ) 10.2 Hz), 7.37 (d, 2 H, J )
8.1 Hz), 7.58 (d, 2 H, J ) 8.8 Hz), 7.88 (d, 2 H, J ) 8.6 Hz), 8.22
(d, 2 H, J ) 9.0 Hz). 13C NMR (CDCl3, 50 MHz): δ 21.6, 124.4,
125.7, 127.3, 130.0, 130.2, 137.7, 141.2, 143.2, 145.0. Anal. Calcd
for C15H13NO4S2: C, 53.73; H, 3.88. Found: C, 53.81; H, 3.65.
1-Methoxy-4-[[(Z)-2-[(4-methylphenyl)sulfonyl]vinyl]sul-
fanyl]benzene, Z-2g. White solid. Mp: 138-139 °C. IR (KBr):
ν 3385, 1493, 1249. 1H NMR (CDCl3, 200 MHz): δ 2.45 (s, 3 H),
3.80 (s, 3 H), 6.18 (d, 1 H, J ) 10.2 Hz), 6.88 (d, 2 H, J ) 9.0
Hz), 7.11 (d, 1 H, J ) 10.2 Hz), 7.35 (d, 2 H, J ) 8.1 Hz), 7.37
(d, 2 H, J ) 9.0 Hz), 7.91 (d, 2 H, J ) 8.3 Hz). 13C NMR (CDCl3,
50 MHz): δ 21.6, 55.4, 115.0, 122.0, 125.1, 127.1, 129.7, 133.7,
138.4, 144.4, 148.0, 160.3. Anal. Calcd for C16H16O3S2: C, 60.00;
H, 5.00. Found: C, 60.14; H, 4.92.
1-Methyl-4-[[(E)-2-[(4-nitrophenyl)sulfanyl]vinyl]sulfonyl]-
benzene, E-2f. Pale yellow oil. IR (CHCl3): ν 2926, 1599, 1306.
1H NMR (CDCl3, 200 MHz): δ 2.48 (s, 3 H), 7.24 (d, 1 H, J )
14.2 Hz), 7.39 (d, 2 H, J ) 8.1 Hz), 7.57 (d, 1 H, J ) 14.2 Hz),
7.76 (d, 2 H, J ) 9.0 Hz), 7.81 (d, 2 H, J ) 9.0 Hz), 8.43 (d, 2 H,
J ) 9.0 Hz). 13C NMR (CDCl3, 50 MHz): δ 21.7, 124.6, 125.1,
125.4, 128.2, 130.4, 135.4, 135.4, 145.9, 146.8, 147.7. Anal. Calcd
for C15H13NO4S2: C, 53.73; H, 3.88. Found: C, 53.68; H, 3.70.
1-Methoxy-4-[[(E)-2-[(4-methylphenyl)sulfonyl]vinyl]sul-
fanyl]benzene, E-2g. White solid. Mp: 87-88 °C. IR (KBr): ν
1
3853, 1496, 1302. H NMR (CDCl3, 200 MHz): δ 2.42 (s, 3 H),
3.82 (s, 3 H), 5.83 (d, 1 H, J ) 14.4 Hz), 6.92 (d, 2 H, J ) 8.8
Hz), 7.30 (d, 2 H, J ) 8.5 Hz), 7.36 (d, 2 H, J ) 9.0 Hz), 7.69 (d,
2 H, J ) 9.3 Hz), 7.75 (d, 1 H, J ) 14.4 Hz). 13C NMR (CDCl3,
50 MHz): δ 21.5, 55.4, 115.5, 118.9, 122.8, 127.3, 129.8, 135.7,
138.1, 143.9, 146.8, 161.0. Anal. Calcd for C16H16O3S2: C, 60.00;
H, 5.00. Found: C, 59.87; H, 4.79.
Procedure for the Reaction between p-Toluene-
sulfonylacetylene 1 and Benzenethiol. To a solution of
p-toluenesulfonylacetylene 1 (0.33 mmol) in MeOH (3 mL) was
added benzenethiol (0.30 mmol). The mixture was stirred at
room temperature for 5 h. The solvent was removed in vacuo
General Procedure for the Synthesis of E-2-Sulfanyl-
vinyl Sulfone Derivatives (E-2a-g). Thiol (0.30 mmol) was
added to a stirred suspension of NaH (0.33 mmol, 60% in mineral
oil) in THF at 0 °C. After 10 min, the solution was added
dropwise to a solution of p-toluenesulfonylacetylene 1 (0.33
J. Org. Chem, Vol. 70, No. 2, 2005 737

without heating. The ratio of products (Z-2e, E-2e, and 4) was
determined in the 1H NMR spectra of the crude residue product.
The crude residue was purified by column chromatography on
silica gel using a mixture of hexanes-EtOAc (10:1) as eluant.
Compound 4 has been previously described as the bisthiosulfo-
nylethane derivative.3
1-[[2,2-Bis(phenylsulfanyl)ethyl]sulfonyl]-4-methylben-
zene, 4. Pale yellow oil. IR (CHCl3): ν 3042, 2399, 1323. 1H NMR
(CDCl3, 200 MHz): δ 2.38 (s, 3 H), 3.45 (d, 2 H, J ) 6.6 Hz),
4.68 (t, 1 H, J ) 6.6 Hz), 7.19-7.28 (m, 8 H), 7.31-7.36 (m, 4
H), 7.65 (d, 2 H, J ) 8.3 Hz). 13C NMR (CDCl3, 50 MHz): δ 21.7,
50.6, 60.3, 128.4, 128.6, 129.2, 129.8, 132.3, 133.3, 133.4, 145.0.
Anal. Calcd for C21H20O2S3: C, 63.00; H, 5.00. Found: C, 62.89;
H, 5.13.
Acknowledgment. Ministerio de Ciencia y Tecno-
log´ıa of Spain (Project BQU2003-04967), Consejer´ıa de
Educacio´n de la C.A.M (Spain), and COVEX S.A. are
gratefully thanked for financial support. Thanks are
also due to Professors Dr. Aurelio G. Csa´ky¨ and Dr.
Pilar Goya for fruitful discussions.
Supporting Information Available: 1H NMR and 13C
NMR spectra copies for compounds Z-2a-d and E-2-d. 1H
NMR and 13C NMR spectra copies for compounds Z-2e-g,
E-2e-g, and 4 have been previously submitted.3 This material
is available free of charge via the Internet at http://pubs.acs.org.
JO0402576
738 J. Org. Chem., Vol. 70, No. 2, 2005