Copper-catalyzed addition of halide and sulfide groups to alkynes utilizing disulfides with tetrabutylammonium halides

Article abstract of DOI:10.1055/s-2008-1042903

A copper-catalyzed addition of halide and sulfide groups to internal alkynes was carried out using disulfides with n-Bu₄NX (X = Br, I or Cl) in air. The present reaction can selectively prepare the corresponding anti-configured haloalkenyl sulfide, and uses both sulfide groups of the disulfide reagent. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2008-1042903

LETTER
849
Copper-Catalyzed Addition of Halide and Sulfide Groups to Alkynes Utilizing
Disulfides with Tetrabutylammonium Halides
C
opper-Catalyzed
o
A
ddition of
b
H
alide and S
u
ulfide
G
roup
k
s
to Alkyne
s
azu Taniguchi*
Department of Chemistry, Fukushima Medical University, Fukushima 960-1295, Japan
E-mail: +81(24)5471369; E-mail: taniguti@fmu.ac.jp
Received 28 November 2007
As an approach to solving this problem, we researched
Abstract: A copper-catalyzed addition of halide and sulfide groups
to internal alkynes was carried out using disulfides with n-Bu4NX
(X = Br, I or Cl) in air. The present reaction can selectively prepare
the corresponding anti-configured haloalkenyl sulfide, and uses
both sulfide groups of the disulfide reagent.
conditions using a copper catalyst in air, and found that
the synthesis of alkenyl sulfide having halide could be
carried out. In this paper, we describe this methodology.
To introduce both halide and sulfide groups to alkyne us-
ing a copper catalyst, bromosulfenylation of alkyne using
4-octyne (1; 0.2 mmol), diphenyl disulfide (2; 0.1 mmol)
and CuI–bpy (1:1, 5 mol%) in AcOH was examined
(Table 1). Initially, when dibromoethane, N-bromosuc-
cinimide (NBS) or KBr were employed, the reaction did
not give satisfying results (entries 1–3). Surprisingly, the
use of n-Bu4NBr (TBAB) could afford (E)-4-bromo-5-
phenylthiooctene 3 in 81% yield without other isomers
(entry 4).7 The stereochemistry of 3 was determined by
NOE after a debromination using the Pd(PPh3)4 catalyst
and MeONa.8 Herein obtained alkene was (Z)-phenyl-
thiooctene 4 (Scheme 2).3a,9 This result suggested that the
addition to alkyne was anti-selective.
Key words: alkenyl sulfides, alkenyl halides, copper catalyst, di-
sulfides, internal alkynes
A transition-metal-catalyzed carbon–sulfur bond forma-
tion by introduction of organothio groups to alkynes is an
important method for convenient synthesis of alkenyl sul-
fides.1 To prepare these compounds, hydrosulfidation or
disulfidation of terminal alkynes has been performed with
Pd or Rh catalysts.2,3 These procedures can afford syn-ad-
ditive products. Although anti-additive products can be
synthesized by using a stoichiometric amount of Lewis
acid4 or by additions of sulfenyl and/or sulfonyl halide,5
effective catalytic methods have not been developed so
far. For instance, Lewis acid cannot be used as a catalyst,
and sulfenyl halide has been prepared from disulfide with
chlorine gas.
On the other hand, the use of other ligands [1,10-phenan-
throline (o-phen), TMEDA or PPh3] decreased the yield
(entries 5–7),10 and other solvents (DMF, DMSO, dioxane
or toluene) did not afford the product at all. Although the
procedure could use CuI or CuBr, reactions using other
copper salts provided low yields (entries 9–11).
Furthermore, the synthesis of anti-additive products by a
combination of disulfide with the transition-metal catalyst
has not been explored. The lack of such methodologies
can be attributed to the lower activity of the generated
metal monosulfide intermediate.
The present method could also introduce other halides to
alkynes (Scheme 3). Alkenyl sulfides having iodide or
chloride group were obtained in 77% or 42% yields, re-
spectively, from tetrabutylammonium iodide or chloride.
To carry out anti addition to alkyne using disulfide, usu-
ally the generation of sulfenyl cation is required. Howev-
er, in a metal-catalyzed reaction, both sulfenyl cation and
metal monosulfide are formed (Scheme 1).6 To accelerate
the catalytic reaction, the oxidation of R¢S–[M] species is
required in order to reproduce disulfide and the metal cat-
alyst.
A variety of alkynes underwent the addition of bromide
and sulfide groups. As shown in Table 2, reactions of
symmetrical 1,2-substituted alkynes could selectively af-
ford the desired anti-configured alkenyl sulfides in good
yields (entries 1–11).11 The use of unsymmetrical 1,2-sub-
stituted alkyne also gave the corresponding alkenyl sul-
R'
X
R
R
S+
R
R
X–
R
R'S+
(R'S)2
[M]
SR'
R
+
[O]
R'S-[M]
Scheme 1 Strategy for the addition of halide and sulfide groups to alkynes
SYNLETT 2008, No. 6, pp 0849–0852
x
x.
x
x.
2
0
0
8
Advanced online publication: 11.03.2008
DOI: 10.1055/s-2008-1042903; Art ID: U12007ST
© Georg Thieme Verlag Stuttgart · New York

850
N. Taniguchi
LETTER
Table 1 Copper-Catalyzed Bromosulfenylation of 4-Octyne Using
Table 2 Copper-Catalyzed Bromosulfenylation of Alkyne Using
(PhS)2 with TBAB in Aira
Disulfide with TBAB in Aira
Cu-L (5 mol%),
CuI-bpy (5 mol%),
R2
Br
Pr
Pr
Br
additive
TBAB
1
1
(R3S)2
R1
R2
/
2
(PhS)2
Pr
Pr
+
/
2
+
AcOH, 100 ºC,
in air
AcOH, in air,
100 °C, 18 h
SR3
R1
SPh
1
2
3
6
7
8
Entry
Cu–L
Additive
(BrCH2)2
NBS
3 (%)b
trace
0
Entry 6 (R1, R2)
7
Time 8 (%)b
(h) (E/Z)
1
2
CuI–bpy
CuI–bpy
CuI–bpy
CuI–bpy
CuI–phen
1
R1 = R2 = n-Pr
R1 = R2 = n-Pr
R1 = R2 = n-Pr
R1 = R2 = n-Pr
R1 = R2 = n-Pr
R1 = R2 = n-Pr
R1 = R2 = n-Pr
R1 = R2 = n-Pr
R1 = R2 = n-Pr
R1 = R2 = Et
(PhS)2
18 81
18 85
2
(4-MeC6H4S)2
3
KBr
38
3
(4-MeOC6H4S)2 18 87
(4-BrC6H4S)2 18 65
(4-O2NC6H4S)2 24 45
4
TBAB
TBAB
TBAB
TBAB
TBAB
TBAB
TBAB
TBAB
81
4
5
65
5
6
CuI–TMEDA
CuI–PPh3
21
6
(MeS)2
18 74
18 76
18 81
18 94
18 71
42 70
7
25
7
(n-BuS)2
(PhCH2S)2
(PhSe)2
8
CuBr–bpy
CuCl–bpy
CuBr2–bpy
CuCl2–bpy
77
8
9
5
9
10
11
15
10
11
12
13
14
15
16
17
(PhS)2
trace
R1 = R2 = Ph
(4-MeC6H4S)2
(PhS)2
a Reaction conditions: The mixture of 4-octyne (1; 0.2 mmol), 2 (0.1
mmol), Cu–L (1:1, 5 mol%) and additive (0.21 mmol) in AcOH (0.3
mL) was treated at 100 °C.
R1 = Ph, R2 = Me
R1 = Ph, R2 = Me
R1 = Ph, R2 = Et
18 94 (98:2)c
18 80
b Isolated yields.
(PhSe)2
(PhS)2
18 86
11%
R1 = Ph, R2 = CH2OH (PhS)2
R1 = Ph, R2 = CH2OH (PhSe)2
R1 = Me, R2 = CH2OH (PhS)2
48 69d
MeONa,
15%
H2C Et
SPh
Pr
H
Br
Pr
Pd(PPh3)4 (10 mol%)
48 84d
DMF, 100 °C, 18 h
H2C
SPh
36 85d
(87:13)c
Et
3
4 92%
R1 = Ph, R2 = H
(PhS)2
18 28 (65:35)c
Scheme 2 Debromination with cat. Pd(PPh3)4 and MeONa
18
a Reaction conditions: The mixture of 6 (0.2 mmol), 7 (0.1 mmol),
CuI–bpy (1:1, 5 mol%) and TBAB (0.21 mmol) in AcOH (0.3 mL)
was treated at 100 °C.
CuI-bpy (5 mol%),
X
Pr
n-Bu4NX
1
/
2 (PhS)2
Pr
Pr
+
b Isolated yields after silica gel chromatography.
c Determined by 1H NMR.
AcOH,100 °C, in air,
18 h
Pr
SPh
1
2
5
d Hydroxy groups of 8 were converted into acetoxy groups.
X = I: 77%
Cl: 42%
n-Bu4NI,
CuI-bpy (5 mol%)
Scheme 3 Copper-catalyzed halosulfenylation of 4-octyne
I
Pr
1
Pr
Pr
+
/
2
(PhS)2
AcOH, 100 °C, 18 h,
under N2
Pr
SPh
fide, however, the selectivity was slightly decreased
(entries 12 and 17).12 In the reaction of diphenylacetylene
or unsymmetrical alkynes, acetoxysulfide derivatives
were detected as a minor product by NMR analysis (en-
tries 11–17). Not only disulfide but also diselenide partic-
ipated in this addition (entries 9, 13 and 16).
Unfortunately, the reaction with a terminal alkyne result-
ed in a low yield of 8 (entry 18).
1
2
9
22%
Scheme 4 Reaction of 4-octyne with disulfide in the absence of
oxygen
under a nitrogen atmosphere, alkenyl sulfide 9 was ob-
tained in only 22% yield with recovery of disulfide
(Scheme 4).
The reactivity of PhSCu(I) (10),13 considered as an inter-
mediate, was also examined. The reaction of the complex
10 with 4-octyne (1) in air could afford the expected alk-
Next, to investigate the reaction mechanism, we examined
both the reaction in the absence of oxygen and the reactiv-
ity of a copper–phenylsulfide complex. When the reaction
of 4-octyne (1) with diphenyl disulfide (2) was carried out
Synlett 2008, No. 6, 849–852 © Thieme Stuttgart · New York

LETTER
Copper-Catalyzed Addition of Halide and Sulfide Groups to Alkynes
851
I
Pr
Acknowledgment
n-Bu4NI, bpy
Pr
Pr
+
PhSCu
This work was financially supported by a Grant-in-Aid for Scienti-
fic Research (No. 19750081) from the Ministry of Education, Sci-
ence, Sports and Technology, Japan.
AcOH, 100 °C,
18 h
Pr
SPh
1
10
9
in air: 49%
under N2: 10%
References and Notes
Scheme 5 Reactivity of PhSCu with 4-octyne
(1) (a) Ley, S. V.; Thomas, A. W. Angew. Chem. Int. Ed. 2003,
42, 5400. (b) Kondo, T.; Mitsudo, T. Chem. Rev. 2000, 100,
3205. (c) Han, L.-B.; Tanaka, M. Chem. Commun. 1999,
395.
(2) (a) Kuniyasu, H.; Ogawa, A.; Sato, K.-I.; Ryu, I.; Kambe,
N.; Sonoda, N. J. Am. Chem. Soc. 1992, 114, 5902.
(b) Ananikov, V. P.; Kabeshov, M. A.; Beletskaya, I. P.;
Khrustalev, V. N.; Antipin, M. Y. Organometallics 2005,
24, 1275. (c) Ogawa, A.; Kuniyasu, H.; Sonoda, N.; Hirao,
T. J. Org. Chem. 1997, 62, 8361. (d) Bäckvall, J.-E.;
Ericsson, A. J. Org. Chem. 1994, 59, 5850. (e) Kuniyasu,
H.; Ogawa, A.; Miyazaki, S.-I.; Ryu, I.; Kambe, N.; Sonoda,
N. J. Am. Chem. Soc. 1991, 113, 9796.
Ph
X
R2
X–
S+
R1
R2
R2
R1
R1
SPh
15
6
16
PhS+ or
13
PhS+-SPh
[Cu]
+ I–
PhSCu(I)Ln
14
(O2)
H+, O2
Cu(I)ILn
(PhS)2
2
2
(3) (a) Ogawa, A.; Ikeda, T.; Kimura, K.; Hirao, T. J. Am. Chem.
Soc. 1999, 121, 5108. (b) Arisawa, M.; Yamaguchi, M. Org.
Lett. 2001, 3, 763.
Scheme 6 A plausible mechanism
(4) Usugi, S.-I.; Yorimitsu, H.; Shinokubo, H.; Oshima, K. Org.
Lett. 2004, 6, 60.
(5) (a) Okuyama, T.; Izawa, K.; Fueno, T. J. Org. Chem. 1974,
39, 351. (b) Amiel, Y. J. Org. Chem. 1974, 39, 3867.
(c) Truce, W. E.; Goralski, C. T.; Christensen, L. W.; Bavry,
R. H. J. Org. Chem. 1970, 35, 4217. (d) Truce, W. E.;Wolf,
G. C. J. Org. Chem. 1971, 36, 1727.
n-Bu4NBr (11 mmol),
Cu-bpy (5 mol%),
Br
Pr
Pr
SPh
Pr
Pr
+
1/2(PhS)2
AcOH (15 mL),
in air,
100 °C, 24 h
2
1
3
1.1 g
(5 mmol)
1.1 g
(10 mmol)
2.3 g (79%)
(6) Taniguchi, N. J. Org. Chem. 2006, 71, 7874.
(7) Typical Procedure: To a mixture of CuI (1.9 mg, 0.01
mmol), bpy (1.6 mg, 0.01 mmol), diphenyl disulfide (21.8
mg, 0.1 mmol), and TBAB (70.9 mg, 0.22 mmol) in AcOH
(0.3 mL) was added 4-octyne (22.0 mg, 0.2 mmol), and the
mixture was stirred at 100 °C for 18 h in air. After the residue
was dissolved in Et2O, the solution was washed with H2O
and sat. NaCl and dried over anhyd MgSO4.
Scheme 7 Large-scale reaction
enyl sulfide 9 in 49% yield, but the reaction in the absence
of oxygen gave only 10% yield (Scheme 5). Therefore,
oxygen is necessary for the present reaction, and it seems
that the disulfide could be reproduced from PhSCu under
acidic conditions.6
Chromatography on silica gel(hexane) gave (E)-4-bromo-5-
phenylthiooctene (48.7 mg, 81%).
(E)-n-Pr(PhS)C=C(Br)n-Pr: IR (neat): 2960, 2870, 1582,
1476, 1461 cm–1. 1H NMR (270 MHz, CDCl3): d = 7.16–
7.31 (m, 5 H), 2.90 (t, J = 7.5 Hz, 2 H), 2.38 (t, J = 7.5 Hz, 2
H), 1.51–1.67 (m, 4 H), 0.92 (t, J = 7.5 Hz, 3 H), 0.86 (t, J =
7.5 Hz, 3 H). 13C NMR (67.5 MHz, CDCl3): d = 135.3,
132.8, 131.5, 129.2, 128.9, 126.2, 41.2, 38.8, 21.9, 21.0,
13.6, 13.1. Anal. Calcd for C14H19SBr: C, 56.19; H, 6.40.
Found: C, 56.09; H, 6.27.
(E)-n-Pr(PhS)C=C(I)n-Pr: IR (neat): 2959, 1582, 1476,
1461 cm–1. 1H NMR (270 MHz, CDCl3): d = 7.16–7.31 (m,
5 H), 2.94 (t, J = 7.3 Hz, 2 H), 2.39 (t, J = 7.3 Hz, 2 H), 1.50–
1.66 (m, 4 H), 0.92 (t, J = 7.3 Hz, 3 H), 0.87 (t, J = 7.3 Hz, 3
H). 13C NMR (67.5 MHz, CDCl3): d = 135.5, 135.4, 129.3,
128.9, 126.4, 113.0, 45.4, 43.9, 22.9, 21.3, 13.5, 12.9. Anal.
Calcd for C14H19SI: C, 48.56; H, 5.53. Found: C, 48.48; H,
5.47.
From these results, the following reaction mechanism was
considered (Scheme 6). After the CuI catalyst acts on the
disulfide as a Lewis acid or oxidant in air,14 a sulfenium
ion 15 and PhSCu(I) 14 are formed by the reaction of in-
termediates 13 with alkyne 6. Sequentially, alkenyl sul-
fide 16 is obtained,15 and PhSCu 14 gives disulfide 2 and
Cu(I)ILn again under acidic conditions in air because 14
cannot carry out sulfenylation of 1 by itself.6
Herein developed method can be carried out on a larger
preparative scale. The bromosulfenylation of 4-octyne (1;
1.1 g, 10 mmol) using (PhS)2 (2; 1.1 g, 5 mmol) and
TBAB (3.5 g, 11 mmol) afforded (E)-4-bromo-5-phen-
ylthiooctene 3 (2.3 g) in 79% yield (Scheme 7).
(8) Zask, A.; Helquist, P. J. Org. Chem. 1978, 43, 1619.
(9) (Z)-n-Pr(H)C=C(SPh)n-Pr: IR (neat): 2958, 1583, 1476
cm–1. 1H NMR (270 MHz, CDCl3): d = 7.11–7.29 (m, 5 H),
5.90 (t, J = 7.1 Hz, 1 H), 2.31 (q, J = 7.2 Hz, 2 H), 2.14 (t,
J = 7.2 Hz, 2 H), 1.36–1.56 (m, 4 H), 0.92 (t, J = 7.2 Hz, 3
H), 0.82 (t, J = 7.2 Hz, 3 H). The NOE was observed at two
allyl positions {(CH2CH=, 15%) and [=C(SPh)CH2, 11%]}
on irradiation at d = 5.90 ppm (=CH). 13C NMR (67.5 MHz,
CDCl3): d = 136.7, 135.8, 133.0, 129.2, 128.7, 125.6, 39.6,
In conclusion, we achieved a copper-catalyzed addition of
halide and sulfide groups to internal alkynes using disul-
fide with tetrabutylammonium halide in air. The present
reaction could be used to prepare the corresponding alke-
nyl sulfide with halide in anti-selective fashion, and use
both sulfide groups on disulfide.
Synlett 2008, No. 6, 849–852 © Thieme Stuttgart · New York

852
N. Taniguchi
LETTER
31.9, 22.7, 21.6, 13.8, 13.3. Anal. Calcd for C14H20SBr: C,
76.30; H, 9.15. Found: C, 76.03; H, 8.92.
9 H). 13C NMR (67.5 MHz, CDCl3): d = 132.4, 128.9, 40.9,
37.8, 32.5, 31.9, 21.9, 21.8, 21.1, 13.6, 13.0. Anal. Calcd for
C12H23SBr: C, 51.61; H, 8.30. Found: C, 51.36; H, 8.17.
(E)-n-Pr(BnS)C=C(Br)n-Pr: IR (neat): 2960, 2929, 1601,
1494, 1453 cm–1. 1H NMR (270 MHz, CDCl3): d = 7.19–
7.31 (m, 5 H), 3.80 (s, 2 H), 2.65 (t, J = 7.2 Hz, 2 H), 2.48 (t,
J = 7.5 Hz, 2 H), 1.53–1.67 (m, 2 H), 1.36–1.49 (m, 2 H),
0.94 (t, J = 7.4 Hz, 3 H), 0.81 (t, J = 7.4 Hz, 3 H). 13C NMR
(67.5 MHz, CDCl3): d = 137.8, 131.8, 131.5, 128.8, 128.5,
127.0, 40.7, 38.5, 37.9, 21.7, 21.0, 13.6, 12.9. Anal. Calcd
for C15H21SBr: C, 57.50; H, 6.76. Found: C, 57.15; H, 6.85.
(E)-n-Pr(PhSe)C=C(Br)n-Pr: IR (neat): 2959, 2929, 1608,
1577, 1475 cm–1. 1H NMR (270 MHz, CDCl3): d = 7.36–
7.42 (m, 2 H), 7.23–7.28 (m, 3 H), 2.89 (t, J = 7.4 Hz, 2 H),
2.41 (t, J = 7.4 Hz, 2 H), 1.46–1.69 (m, 4 H), 0.92 (t, J = 7.2
Hz, 3 H), 0.86 (t, J = 7.2 Hz, 3 H). 13C NMR (67.5 MHz,
CDCl3): d = 132.1, 130.6, 129.5, 129.3, 129.2, 127.1, 43.3,
40.7, 21.9, 21.3, 13.5, 13.0. Anal. Calcd for C14H19SeBr: C,
48.58; H, 5.53. Found: C, 48.82; H, 5.54.
(10) In the absence of bpy, the yield of 3 was 39% yield.
(11) (E)-n-Pr(4-MeC6H4S)C=C(Br)n-Pr: IR (neat): 2960,
2929, 1894, 1602, 1491 cm–1. 1H NMR (270 MHz, CDCl3):
d = 7.15 (d, J = 8.3 Hz, 2 H), 7.09 (d, J = 8.3 Hz, 2 H), 2.90
(t, J = 7.4 Hz, 2 H), 2.34 (t, J = 7.4 Hz, 2 H), 2.32 (s, 3 H),
1.49–1.67 (m, 4 H), 0.93 (t, J = 7.4 Hz, 3 H), 0.86 (t, J = 7.4
Hz, 3 H). 13C NMR (67.5 MHz, CDCl3): d = 136.5, 132.2,
131.5, 131.4, 130.1, 129.8, 41.2, 38.5, 21.9, 21.0, 13.6, 13.1.
Anal. Calcd for C15H21SBr: C, 57.50; H, 6.76. Found: C,
57.21; H, 6.67.
(E)-n-Pr(4-MeOC6H4S)C=C(Br)n-Pr: IR (neat): 2960,
2930, 1592, 1493 cm–1. 1H NMR (270 MHz, CDCl3): d =
7.24 (d, J = 8.9 Hz, 2 H), 6.84 (d, J = 8.9 Hz, 2 H), 3.79 (s,
3 H), 2.91 (t, J = 7.3 Hz, 2 H), 2.28 (t, J = 7.5 Hz, 2 H), 1.48–
1.68 (m, 4 H), 0.94 (t, J = 7.4 Hz, 3 H), 0.85 (t, J = 7.4 Hz, 3
H). 13C NMR (67.5 MHz, CDCl3): d = 159.2, 133.3, 132.8,
129.5, 125.1, 114.6, 55.3, 41.1, 38.0, 21.9, 20.9, 13.6, 13.1.
Anal. Calcd for C15H21OSBr: C, 54.71; H, 6.43. Found: C,
54.53; H, 6.38.
(E)-Ph(Br)C=C(SPh)Me: IR (neat): 3057, 1581, 1475,
1439 cm–1. 1H NMR (270 MHz, CDCl3): d = 7.24–7.41 (m,
10 H), 2.21 (s, 3 H). 13C NMR (67.5 MHz, CDCl3): d =
140.5, 134.5, 130.5, 130.2, 129.1, 129.0, 128.5, 128.1,
126.9, 123.3, 24.9. Anal. Calcd for C15H13SBr: C, 59.02; H,
4.29. Found: C, 58.94; H, 4.37.
(E)-n-Pr(4-BrC6H4S)C=C(Br)n-Pr: IR (neat): 2960, 2929,
1889, 1603, 1471 cm–1. 1H NMR (270 MHz, CDCl3): d =
7.40 (d, J = 8.6 Hz, 2 H), 7.08 (d, J = 8.6 Hz, 2 H), 2.87 (t,
J = 7.2 Hz, 2 H), 2.37 (t, J = 7.7 Hz, 2 H), 1.49–1.67 (m, 4
H), 0.92 (t, J = 7.4 Hz, 3 H), 0.87 (t, J = 7.4 Hz, 3 H). 13
C
(E)-Ph(Br)C=C(SPh)CH2OAc: IR (neat): 3058, 1743,
1581, 1477, 1440 cm–1. 1H NMR (270 MHz, CDCl3): d =
7.20–7.41 (m, 10 H), 4.96 (s, 2 H), 2.00 (s, 3 H). 13C NMR
(67.5 MHz, CDCl3): d = 170.4, 139.7, 133.9, 130.3, 129.4,
129.3, 129.0, 128.8, 128.1, 127.2, 66.2, 20.6. Anal. Calcd for
C17H15O2SBr: C, 56.21; H, 4.16. Found: C, 56.32; H, 4.25.
(12) The stereochemistry of compounds in entries 12 and 14 was
determined by NOE after the debromination.
NMR (67.5 MHz, CDCl3): d = 134.7, 133.7, 132.0, 130.9,
130.2, 120.1, 41.3, 38.8, 21.9, 21.0, 13.6, 13.0. Anal. Calcd
for C14H18SBr2: C, 44.46; H, 4.80. Found: C, 44.32; H, 4.89.
(E)-n-Pr(MeS)C=C(Br)n-Pr: IR (neat): 2960, 2928, 1602,
1459 cm–1. 1H NMR (270 MHz, CDCl3): d = 2.81 (t, J = 7.2
Hz, 2 H), 2.48 (t, J = 7.7 Hz, 2 H), 2.20 (s, 3 H), 1.54–1.63
(m, 4 H), 0.95 (t, J = 5.3 Hz, 3 H), 0.91 (t, J = 5.3 Hz, 3 H).
13C NMR (67.5 MHz, CDCl3): d = 133.4, 127.4, 40.8, 37.4,
21.7, 21.0, 16.4, 13.6, 12.9. Anal. Calcd for C9H17SBr: C,
45.57; H, 7.22. Found: C, 45.60; H, 6.93.
(13) For the preparation of PhSCu, see: Adams, R.;
Reifschneider, W.; Ferretti, A. Org. Synth., Coll. Vol. V;
John Wiley & Sons: New York, 1973, 107–110.
(E)-n-Pr(n-BuS)C=C(Br)n-Pr: IR (neat): 2960, 2929,
1601, 1462 cm–1. 1H NMR (270 MHz, CDCl3): d = 2.84 (t,
J = 7.4 Hz, 2 H), 2.61 (t, J = 7.1 Hz, 2 H), 2.45 (t, J = 7.6 Hz,
2 H), 1.51–1.65 (m, 6 H), 1.36–1.48 (m, 2 H), 0.88–0.94 (m,
(14) Takeuchi, H.; Hiyama, T.; Kamai, N.; Oya, H. J. Chem. Soc.,
Perkin Trans. 2 1997, 2301.
(15) When PhSCu was treated with acetic acid, (PhS)2 was
obtained in 80% yield.
Synlett 2008, No. 6, 849–852 © Thieme Stuttgart · New York