Catalyst-Free, Regioselective Ring Opening of Donor-Acceptor Cyclopropanes: Synthesis of Functionalized Mono- and Disulfides

Article abstract of DOI:10.1055/s-0035-1561629

Interesting sulfur compounds such as monosulfides, symmetrical disulfides, unsymmetrical disulfides, and other 1,3-bifunctionalized compounds were synthesized using benzyltriethylammonium tetrathiomolybdate, [BnNEt₃]₂MoS₄, as the sulfur transfer reagent via regioselective ring opening of donor-acceptor cyclopropanes without the addition of any catalyst.

Full text of DOI:10.1055/s-0035-1561629

SYNTHESIS
0
0
3
9
-
7
8
8
1
1
4
3
7
-
2
1
0
X
© Georg Thieme Verlag Stuttgart · New York
2016, 48, A–J
paper
A
P. Gopinath, S. Chandrasekaran
Paper
Synthesis
Catalyst-Free, Regioselective Ring Opening of Donor–Acceptor
Cyclopropanes: Synthesis of Functionalized Mono- and Disulfides
Purushothaman Gopinath
Srinivasan Chandrasekaran*
Ar
S
NO2
S
EWG
EWG
2
ArS–SAr
R
R
Ph3P, NBS
CHCl3, r.t., 3 h
R = H, Me, Br
MeCN
r.t., 2–7.5 h
EWG = CN, CO2Et,
CONH2, Ac
R' = H, CN, Cl, NO2
Department of Organic Chemistry,
Indian Institute of Science, Bangalore
560012, India
3 examples
50–70%
7 examples
55–75%
EWG
EWG
scn@orgchem.iisc.ernet.in
R
2–
+
MoS4
Ph
Ar
S
S
NO2
CO2Et
S
NO2
ArCH2S–SCH2Ar
MeCN, r.t., 3.5 h
O
PhCOOH
R
R
Ph3P, NBS
CHCl3, r.t., 5 h
CO2Et
R = H, Me, Br
6 examples
50–75%
R' = H, OMe, Me, Cl
60%
Received: 24.02.2016
Accepted after revision: 04.04.2016
Published online: 13.05.2016
teins.3 The most common method for the synthesis of mo-
nosulfides involves the alkylation of thiols with bases.2a,4
Other methods involve metal-mediated cross-coupling re-
actions (between aryl/alkyl halide and thiols and hydrothi-
olation of alkynes),5 Michael addition of thiols,6 addition of
thiols to alkenes,7 etc. On the other hand, the most com-
monly employed method for the synthesis of disulfides in-
volves the oxidation of the corresponding thiols, and for
mixed disulfides,8 the most common method is the activa-
tion of thiols via sulfenyl derivatives followed by nucleo-
philic substitution with another thiol partner. But the main
disadvantage of this method is the use of free thiols, harsh
reaction conditions, disulfide-thiol exchange reactions,9
higher temperature, use of excess base, isolation of activat-
ed sulfenyl derivatives, etc. Thus, an alternative and mild
protocol for their synthesis is desirable.
DOI: 10.1055/s-0035-1561629; Art ID: ss-2016-t0131-op
Abstract Interesting sulfur compounds such as monosulfides, sym-
metrical disulfides, unsymmetrical disulfides, and other 1,3-bifunction-
alized compounds were synthesized using benzyltriethylammonium
tetrathiomolybdate, [BnNEt3]2MoS4, as the sulfur transfer reagent via
regioselective ring opening of donor–acceptor cyclopropanes without
the addition of any catalyst.
Key words cyclopropanes, ring opening, monosulfides, disulfides,
thioesters
Functionalized monosulfides and disulfides are an im-
portant class of organic compounds present in many bio-
logically relevant molecules such as methionine, biotin,
gliotoxin, sporidesmin, acetyl aranotin, etc. They find wide
applications in organic synthesis, medicinal chemistry,1
and function as antioxidants.2 Disulfides in particular play
an important role in the folding and stability of a few pro-
Nucleophilic ring opening of donor–acceptor cyclopro-
panes10 is one of the most valuable synthetic tools for the
synthesis of a wide variety of 1,3-bifunctionalized mole-
cules and also a key step in the synthesis of many natural
R'
EWG
CN
2–
EWG
EWG
A
MoS4
S
NH2
diselenides
Se
NO2
CO2Et
R
NaBH4
EWG
R
R
R
previous work
R'
R'
EWG EWG
+
alkyl/aryl
disulfides
B
2–
S
EWG
EWG
MoS4
S
S
NO2
CO2Et
this work
R
R
R
Scheme 1 A: Previous work on cyclopropane ring opening; B: Present work
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–J

B
P. Gopinath, S. Chandrasekaran
Paper
Synthesis
Cl
Cl
CO2Me
NC
MeCN, r.t.
3.5 h, 81%
2–
S
CN
S
+
MoS4
+
S
CO2Me
Cl
2a
1
3a
4
Cl
CO2Me
NC
S
CN
S
+
CO2Me
Cl
3a
4
Scheme 2 Reaction of diphenyl disulfide 2a with cyclopropane 3a
products.11 We recently reported an interesting method for
the synthesis of dihydrothiophenes from cyano-substituted
donor–acceptor cyclopropanes using tetrathiomolybdate12
and also a one-pot protocol for the synthesis of functional-
ized organoselenium compounds via cyclopropane ring
opening.13 In continuation of these studies, we present
herein our work focused on the synthesis of interesting sul-
fur compounds such as monosulfides, disulfides, mixed di-
sulfides, and thioesters using benzyltriethylammonium
tetrathiomolybdate {[BnNEt3]2MoS4, 1}14 as the sulfur
transfer reagent via cyclopropane ring opening (Scheme 1).
In order to avoid the use of thiols as starting materials, it
was decided to use simple organic disulfides as substrates
since tetrathiomolybdate 1 is known to reduce14,15 the di-
sulfide bonds to generate the corresponding thiolates in
situ in an internal redox process. The thiolate ion can then
open the doubly activated cyclopropane ring to furnish the
corresponding functionalized monosulfides. After some ini-
tial screening of reaction conditions, the most optimal reac-
tion conditions was found wherein disulfide 2a and tetra-
thiomolybdate 1 were stirred together in MeCN for 1 hour
to generate the thiolate ion and to this was added cyclopro-
pane 3a. The reaction mixture was then stirred for 2 hours
at room temperature to form the corresponding functional-
ized monosulfide 4 (as a diastereomeric mixture) in 81%
yield (Scheme 2).
This method is advantageous over the existing methods
for the ring opening of cyclopropanes with thiols because of
better yield, mild reaction conditions, shorter reaction
time, and issues related to handling of free thiols. The reac-
tion was then repeated with other organic disulfides and
cyclopropane derivatives as well to show the synthetic util-
ity of the protocol. The results of this study are summarized
in Table 1. It was observed that cyano amide substituted cy-
clopropanes (Table 1, entries 2, 5, and 7) in general are less
reactive as compared to cyano ester substituted cyclopro-
CO2Et
+
O2N
MeCN, r.t
S
2–
S
MoS4
+
S
NO2
S
3.5 h, 70%
OEt
13a
1
12a
O
14
1
1
O2N
CO2Et
O2N
CO2Et
S
OEt
S
S
S
S
S
S
Mo
O
S
S
12a
+
S
NO2
– MoS2
CO2Et
NO2
O2N
CO2Et
13b
Scheme 3 Reaction of dibenzyl disulfide (12a) with cyclopropane 13a
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–J

C
P. Gopinath, S. Chandrasekaran
Paper
Synthesis
panes (entries 1 and 3) and also gave lower yields of the re-
sulting monosulfides. Interestingly, the diester-substituted
cyclopropane derivative 3e (entry 8) did not react under
the conditions to give the expected product (starting mate-
rial recovered).
In the next stage, the synthesis of functionalized mixed
disulfides was carried out starting with simple alkyl disul-
fides, which are known to produce mixed disulfides in the
presence of tetrathiomolybdate 1.16 Accordingly, dibenzyl
disulfide (12a) (alkyl disulfide) on treatment with reagent
1 and cyclopropane 13a gave the mixed disulfide 14 (as a
diastereomeric mixture) in 70% yield. Since dibenzyl disul-
fide is less reactive compared to diphenyl disulfide, reagent
1 first reacts with cyclopropane 13a to form the corre-
sponding disulfide 13b (formed by cyclopropane ring open-
ing), which in the presence of 12a undergoes disulfide ex-
change reaction mediated by tetrathiomolybdate 1 to give
the corresponding mixed disulfide 14 (Scheme 3). The reac-
tion was then carried out on a number of other activated
cyclopropanes and alkyl disulfides and all of them gave the
corresponding mixed disulfides as the major products. The
results of this study are summarized in Table 2.
We have already shown that alkyl halides on treatment
with tetrathiomolybdate, 1 furnishes the corresponding di-
sulfides.17 Hence, we decided to carry out the reaction of an
alkyl halide with 1 to form the corresponding disulfide in
situ, which in turn may be used for the ring opening of cy-
clopropane to provide a mixed disulfide. Accordingly, ben-
Table 1 Synthesis of Functionalized Monosulfides through Cyclopropane Ring Opening
Entry
1
Disulfide
Cyclopropane
Product
Time (h)
3.5
Yield (%)
72
CO2Et
CONH2
CO2Me
S
S
CN
NC
NC
NC
S
S
)
2
CO2Et
2a
3b
5
Cl
Cl
Cl
CN
)
2
CONH2
2
3
4
5
6
7
8
2a
2b
2b
2b
2c
2d
2a
3c
3a
3d
3c
3a
3c
3e
6
7.5
2
62
62
60
60
75
55
–
Cl
S
S
S
CN
S
)
2
CO2Me
7
O2N
O2N
O2N
NC
O2N
COMe
CO2Et
MeOC
S
S
)
2
CO2Et
8
6.5
3
O2N
O2N
NC
CN
CONH2
NC
)
2
CONH2
9
S
CN
CO2Me
CONH2
CO2Et
NC
S
)
2
CO2Me
10
11
2
S
CN
CONH2
NC
S
)
2
3.5
5
EtO2C
S
)
2
no reaction
Cl
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–J

D
P. Gopinath, S. Chandrasekaran
Paper
Synthesis
zyl bromide (20) on treatment with tetrathiomolybdate 1
forms disulfide 12a while the cyclopropane derivative 13a
in the presence of tetrathiomolybdate 1 provides the sym-
metrical disulfide 13b in situ. In the presence of excess
tetrathiomolybdate 1, the two disulfides 12a and 13b
formed undergo an exchange reaction to produce the final
product, the mixed disulfide 14 in 50% yield (Scheme 4).
Table 2 Synthesis of Mixed Disulfides from Nitro Ester Substituted Cyclopropanes
Entry
Disulfide
Cyclopropane
Product
Yield (%)
CO2Et
O2N
S
S
S
)
2
S
1
12a
13a
14
70
S
NO2
OEt
O
CO2Et
O2N
)
2
S
2
3
4
5
12a
12a
12b
12c
13b
13c
13a
13a
15
16
17
18
60
58
50
75
S
NO2
OEt
O
CO2Et
O2N
)
2
S
S
NO2
OEt
Br
O
Br
CO2Et
CO2Et
CO2Et
O2N
O2N
O2N
S
)
2
S
S
NO2
OEt
O
Cl
S
)
2
S
S
NO2
Cl
OEt
O
MeO
S
)
2
S
6
12d
13a
19
75
S
NO2
MeO
OEt
O
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–J

E
P. Gopinath, S. Chandrasekaran
Paper
Synthesis
was attempted the carboxylic acid group decarboxylated
well before its reaction with reagent 1 to give the corre-
sponding nitro cyclopropane derivative 22 (Scheme 5).
In order to prevent decarboxylation at an early stage
triphenylphosphine and NBS were added to form the acyl-
oxyphosphonium salt 21a′,18 which then reacts with re-
agent 1 to give the disulfide intermediate 23a followed by
decarboxylation to give the corresponding disulfide 24a (as
a diastereomeric mixture) in 70% yield (Scheme 6). The re-
action was then carried on with other activated cyclopro-
panes as well to show the synthetic utility of the methodol-
ogy (Table 3).
2–
CO2Et
O2N
MoS4
1
Br
S
+
S
NO2
MeCN, r.t., 5 h
OEt
20
13a
O
1
1
14
1
S
NO2
(
2
OEt
S
S
+
O
12a
13b
The same methodology was then extended to a one-pot
disulfide cleavage, ring opening and decarboxylation se-
quence to form the corresponding monosulfide. According-
ly, 2a was stirred with reagent 1 to generate the corre-
sponding thiolate ion, which then reacts with cyclopropane
21a previously activated with PPh3 and NBS to give the cor-
responding monosulfide 25 in 63% yield (Scheme 7).
Scheme 4 Synthesis of mixed disulfide 14 from benzyl bromide (20)
O
Na
NO2
O
MeCN
r.t., 3 h
2–
NO2
MoS4
+
21a
1
22
Cl
Scheme 5 Reaction of cyclopropane 21a with tetrathiomolybdate 1
S
S
Cl
2a
Since monoactivated cyclopropanes are inert to our re-
agent 1, a synthetic strategy was designed for the formation
of disulfides starting from a doubly activated cyclopropane
followed by the removal of one of the activating groups
during the course of the reaction. For this study, nitro and
carboxylic acid-substituted cyclopropane derivative 21a
was synthesized. When the ring opening reaction on 21a
Cl
+
2–
Ph3P, NBS
MoS4
S
NO2
1
CHCl3, r.t., 4 h
+
CO2Na
O2N
25
21a
Scheme 7 Reaction of disulfide 2a with cyclopropane 21a
O
Na
NO2
(
2
S
2–
CHCl3
O
Ph3P
MoS4
NBS
+
+
+
NO2
r.t., 3 h
1
21a
24a
1
– 2 CO2
O2N
CO2H
O
O2N
C
H2O
S
O
PPh3Br
NO2
S
S
S
Mo
S
S
O
S
S
S
S
O
– MoS2
– PPh3O
C
H2O
NO2
O2N
CO2H
21a'
23a
Scheme 6 Reaction of cyclopropane 21a with tetrathiomolybdate 1 via acyloxyphosphonium intermediate
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–J

F
P. Gopinath, S. Chandrasekaran
Paper
Synthesis
Table 3 Synthesis of Symmetrical Disulfides from Nitro-Substituted Cyclopropanes
Entry
1
Cyclopropane
Product
Yield (%)
CO2H
NO2
21a
24a
70
O2N
(
S
(
2
2
3
21b
21c
24b
24c
60
CO2H
NO2
O2N
S
2
50
CO2H
NO2
(
O2N
S
2
Br
Br
From a synthetic perspective a thioester group could be
readily transformed to a more versatile SH group as com-
pared to thioethers and hence the ring opening of doubly
activated cyclopropane 13a was done with thioacid equiva-
lents. Accordingly, benzoic acid, PPh3, and NBS were stirred
together to generate benzoyloxy phosphonium salt 26a,
which on further treatment with reagent 1, gave the thio-
benzoate ion19 26b. The thiobenzoate ion was then used for
the ring opening of doubly activated cyclopropane 13a to
give the corresponding ring opened product 27 (as a diaste-
reomeric mixture) in 60% yield (Scheme 8).
In conclusion, we have demonstrated the synthetic util-
ity of benzyltriethylammonium tetrathiomolybdate (1) in
the synthesis of various interesting sulfur containing mole-
cules such as monosulfides, symmetrical disulfides, un-
symmetrical disulfides, and other 1,3-bifunctionalized sys-
tems under mild reaction conditions without need for any
Lewis acid activation. Additionally, we have shown an alter-
native protocol for the ring opening of monoactivated cy-
clopropanes by starting from nitro carboxylate-substituted
cyclopropanes.
All reactions were carried out in oven-dried apparatus using anhy-
drous solvents, unless otherwise noted. Reaction mixtures were
stirred magnetically unless otherwise stated. Commercial grade sol-
vents were distilled and dried. Analytical TLC was performed on com-
mercial plates coated with silica gel GF254 (0.25 mm). Silica gel (230–
400 mesh) was used for column chromatography. Yields refer to chro-
matographically and spectroscopically (1H NMR) homogeneous mate-
rials, unless otherwise stated. NMR spectra were recorded on 300 or
400 MHz instruments and calibrated using residual undeuterated sol-
vent as an internal reference. Standard abbreviations are used for the
multiplicities. The superscript abbreviations d1 and d2 shown in the
assignments of 1H NMR refer to diastereomer 1 and diastereomer 2. IR
spectra were recorded on a FT-IR spectrometer. ESI-HRMS were re-
corded on a Q-TOF mass spectrometer.
CO2Et
2–
CO2Et
MoS4
1
O2N
O
O
NO2
+
Ph3P + NBS +
CHCl3, r.t., 5 h
Ph
OH
O
Ph
S
26
13a
27
O2N
Ph
O
Br
PPh3
O
CO2Et
+
26a
Ph
S
26b
13a
– PPh3O
1
1
O
O
S
S
O
S
O
S
O
Ph
Mo
S
Ph
S
+ MoS2
Ph
Mo
Ph
Ph
S
S
Ph
O
S
S
Scheme 8 Synthesis of thioester 27 from cyclopropane 13a and benzoic acid (26)
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–J

G
P. Gopinath, S. Chandrasekaran
Paper
Synthesis
Cyclopropanes 3a–d were synthesized from bromosulfonium bro-
mides (inseparable E/Z mixture was used for the ring-opening reac-
tion).12 Nitro ester-substituted cyclopropanes 13a–c were synthe-
sized using a protocol developed by Charette et al.20 starting from the
corresponding alkene and PhI(OAc)2 (E-isomer was used for the ring-
opening reactions, except for cyclopropane 13b wherein the E/Z mix-
ture were inseparable). Cyclopropanes 21a–c were obtained by the
hydrolysis of the corresponding nitro ester substituted cyclopro-
panes.21 Disulfides 2a, 2d, and 12a are commercially available and di-
sulfides 2b,22 2c,23 12b,24 12c,25 and 12d25 were synthesized starting
from the corresponding thiols using I2 as oxidant.26
13C NMR (75 MHz, CDCl3): δ = 165.9, 165.7, 139.6, 138.4, 134.8, 134.5,
134.3, 131.6, 131.1, 129.2, 129.1, 128.8, 128.4, 128.1, 127.8, 127.5,
117.5, 117.2, 51.5, 50.9, 36.0, 33.5.
HRMS: m/z [M + Na+] calcd for C17H15ClN2OSNa+: 353.0491; found:
353.0487.
Methyl 2-Cyano-4-[(4-nitrophenyl)thio]-4-phenylbutanoate (7)
Light yellow solid; yield: 0.221 g (62%) (50:50 dr); mp 93.2 °C.
IR (neat): 2237, 1715, 1524, 1145 cm–1
.
1H NMR (300 MHz, CDCl3): δ = 8.29–8.21 (m, 2 H), 7.50–7.23 (m, 7 H),
4.64 (dd, J1 = 5.4 Hz, J2 = 10.5 Hz, 1 Hd1), 4.33 (t, J = 8.1 Hz, 1 Hd2), 3.91–
3.83 (m, 1 Hd1), 3.83 (s, 3 Hd1), 3.81 (s, 3 Hd2), 3.66 (dd, J1 = 5.4 Hz, J2 =
10.5 Hz, 1 Hd2), 2.80–2.71 (m, 2 Hd1 + 1 Hd2), 2.48–2.38 (m, 1 Hd2).
13C NMR (75 MHz, CDCl3): δ = 183.9, 169.6, 168.7, 147.9, 141.9, 141.3,
137.9, 129.4, 129.3, 128.3, 128.7, 128.3, 127.6, 127.2, 124.4, 119.0,
118.3, 45.5, 47.4, 47.1, 42.0, 41.0, 35.4, 34.9.
Monosulfides 4–11; General Procedure
To a previously stirred solution (28 °C, 1.5 h) of tetrathiomolybdate 1
(0.609 g, 1.0 mmol) and disulfide 2 (0.8 mmol) in MeCN (10 mL) was
added the corresponding cyclopropane 3 (1.0 mmol). The reaction
mixture was then stirred for the time given in Table 1. The solvent
was removed and the residue was extracted with CH2Cl2 (5 mL) and
Et2O (20 mL), and filtered through a Celite pad. The residue was again
extracted with CH2Cl2 (5 mL) followed by extraction with Et2O (20
mL) and filtered again through a Celite pad. The combined extracts
were evaporated and the residue was purified by column chromatog-
raphy on silica gel to give the corresponding monosulfide as an insep-
arable diastereomeric mixture.
HRMS: m/z [M + Na+] calcd for C18H16N2O4SNa+: 379.0728; found:
379.0728.
Ethyl 2-Acetyl-4-[(4-nitrophenyl)thio]-4-phenylbutanoate (8)
Light yellow liquid; yield: 0.232 g (60%) (50:50 dr).
IR (neat): 1738, 1716, 1514 cm–1
.
1H NMR (300 MHz, CDCl3): δ = 8.08–8.05 (m, 2 H), 7.39–7.30 (m, 7 H),
4.45–4.37 (m, 1 H), 4.28–4.09 (m, 2 H), 3.51–3.40 (m, 1 H), 2.69–2.52
(m, 2 H), 2.21 (s, 3 Hd1), 2.16 (s, 3 Hd2), 1.36–1.20 (m, 3 H).
Methyl 4-[(4-Chlorophenyl)thio]-2-cyano-4-phenylbutanoate (4)
Colorless liquid; yield: 0.280 g (81%) (60:40 dr).
IR (neat): 2250, 1749, 1475 cm–1
.
13C NMR (75 MHz, CDCl3): δ = 202.2, 201.6, 168.9, 168.7, 145.6, 145.4,
139.2, 139.1, 129.1, 128.7, 128.5, 128.3, 128.1, 127.7, 124.2, 123.9,
123.7, 61.8, 57.1, 56.9, 49.1, 34.2, 29.8, 29.1, 14.1, 14.0.
1H NMR (300 MHz, CDCl3): δ = 7.32–7.17 (m, 9 H), 4.34–4.26 (m, 1 H),
3.89 (dd, J1 = 6.3 Hz, J2 = 8.1 Hz, 1 Hd1), 3.76 (s, 3 Hd2), 3.72 (s, 3 Hd1),
3.32 (dd, J1 = 5.7 Hz, J2 = 9.9 Hz, 1 Hd2), 2.65–2.40 (m, 2H).
HRMS: m/z [M + Na+] calcd for C20H21NO5SNa+: 410.1038; found:
13C NMR (75 MHz, CDCl3): δ = 165.9, 165.8, 139.4, 138.3, 134.7, 134.3,
131.6, 129.7, 129.1, 129.0, 128.8, 128.7, 128.3, 128.0, 127.9, 127.7,
115.8, 115.5, 53.6, 53.5, 51.3, 50.7, 35.7, 35.5, 35.3.
410.1034.
2-Cyano-4-[(4-nitrophenyl)thio]-4-phenylbutanamide (9)
HRMS: m/z [M + Na+] calcd for C18H16ClNO2SNa+: 368.0488; found:
Light yellow liquid; yield: 0.205 g (60%) (50:50 dr).
IR (neat): 3448, 3551, 2249, 1693, 1508, 1338 cm–1
.
368.0486.
1H NMR (300 MHz, CDCl3): δ = 8.09–8.05 (m, 2 H), 7.41–7.27 (m, 7 H),
6.15 (br s, 1 H), 5.92 (br s, 1 H), 4.65–4.57 (m, 1 H), 3.58 (t, J = 7.5 Hz, 1
Hd1), 3.22 (dd, J1 = 5.4 Hz, J2 = 10.2 Hz, 1 Hd2), 2.78–2.42 (m, 2 H).
Ethyl 4-[(4-Chlorophenyl)thio]-2-cyano-4-phenylbutanoate (5)
Colorless liquid; yield: 0.259 g (72%) (55:45 dr).
IR (neat): 2251, 1749, 1476, 1262 cm–1
.
13C NMR (75 MHz, CDCl3): δ = 165.6, 165.4, 146.2, 143.8, 138.5, 137.7,
129.6, 129.5, 129.4, 129.2, 128.8, 128.6, 128.1, 127.7, 124.0, 117.3,
117.1, 49.5, 49.2, 36.1, 35.8, 35.4.
1H NMR (300 MHz, CDCl3): δ = 7.33–7.17 (m, 9 H), 4.34–4.09 (m, 3 H),
3.87 (dd, J1 = 6.6 Hz, J2 = 8.1 Hz, 1 Hd1), 3.30 (dd, J1 = 6.0 Hz, J2 = 9.9 Hz,
1 Hd2), 2.88–2.39 (m, 2 H), 1.31–1.22 (m, 3 H).
HRMS: m/z [M + Na+] calcd for C17H15N3O3SNa+: 364.0732; found:
13C NMR (75 MHz, CDCl3): δ = 165.4, 165.3, 139.5, 138.4, 134.8, 134.4,
131.7, 131.2, 129.7, 129.6, 129.2, 129.1, 128.9, 128.8, 128.4, 128.1,
128.0, 127.7, 115.9, 115.7, 63.1, 63.0, 51.4, 50.8, 35.9, 35.8, 35.4, 13.9.
364.0732.
Methyl 2-Cyano-4-[(4-cyanophenyl)thio]-4-phenylbutanoate (10)
HRMS: m/z [M + Na+] calcd for C19H18ClNO2SNa+: 382.0644; found:
Colorless liquid; yield: 0.252 g (75%) (50:50 dr).
IR (neat): 2228, 1749, 1592 cm–1
.
382.0637.
1H NMR (300 MHz, CDCl3): δ = 7.52–7.48 (m, 2 H), 7.37–7.29 (m, 7 H),
4.56–4.49 (m, 1 H), 3.80–3.74 (m, 3 Hd1 + 3 Hd2 + 1 Hd1), 3.30 (dd, J1 =
6.0 Hz, J2 = 9.3 Hz, 1 Hd2), 2.67–2.45 (m, 2 H).
4-[(4-Chlorophenyl)thio]-2-cyano-4-phenylbutanamide (6)
White solid; yield: 0.205 g (62%) (50:50 dr); mp 130.5 °C.
IR (neat): 3442, 3340, 2248, 1689 cm–1
.
13C NMR (75 MHz, CDCl3): δ = 165.7, 141.1 138.6, 137.7, 132.2, 130.6,
130.3, 129.3, 129.1, 128.8, 128.5, 127.7, 118.3, 115.5, 53.7, 49.7, 49.1,
35.9, 35.7, 35.5.
HRMS: m/z [M + Na+] calcd for C19H16N2O2SNa+: 359.0830; found:
359.0831.
1H NMR (300 MHz, CDCl3): δ = 7.33–7.13 (m, 9 H), 6.12 (br s, 1 H),
5.96 (br s, 1 H), 4.33–4.26 (m, 1 H), 3.75 (dd, J1 = 6.3 Hz, J2 = 8.4 Hz, 1
Hd1), 3.20 (dd, J1 = 5.4 Hz, J2 = 10.5 Hz, 1 Hd2), 2.70–2.58 (m, 1 H), 2.50–
2.35 (m, 1 H).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–J

H
P. Gopinath, S. Chandrasekaran
Paper
Synthesis
2-Cyano-4-phenyl-4-(phenylthio)butanamide (11)
Ethyl 4-(Benzyldisulfanyl)-4-(4-bromophenyl)-2-nitrobutanoate
(16)
Light yellow liquid; yield: 0.163 g (55%) (50:50 dr).
Colorless liquid; yield: 0.272 g (58%) (40:60 dr).
IR (neat): 3441, 3342, 2248, 1692, 1684 cm–1
.
IR (neat): 1749, 1559 cm–1
.
1H NMR (300 MHz, CDCl3): δ = 7.34–7.19 (m, 10 H), 6.09 (br s, 1 H),
5.91 (br s, 1 H), 4.37–4.29 (m, 1 H), 3.76 (dd, J1 = 6.3 Hz, J2 = 8.7 Hz, 1
Hd1), 3.21 (dd, J1 = 5.4 Hz, J2 = 10.2 Hz, 1 Hd2), 2.70–2.58 (m, 1 H), 2.51–
2.36 (m, 1 H).
13C NMR (75 MHz, CDCl3): δ = 166.1, 165.9, 140.0, 138.8, 133.4, 133.0,
129.0, 128.9, 128.7, 128.2, 128.0, 127.9, 127.8, 117.3, 116.1, 51.2, 50.7,
36.2, 36.1, 35.74, 35.69.
1H NMR (400 MHz, CDCl3): δ = 7.49–6.93 (m, 9 H), 5.16 (dd, J1 = 6.0
Hz, J2 = 8.8 Hz, 1 Hd1), 4.71 (dd, J1 = 3.6 Hz, J2 = 11.2 Hz, 1 Hd2), 4.28–
4.17 (m, 2 H), 3.72 (d, J = 12.5 Hz, 1 Hd2), 3.66 (d, J = 12.6 Hz, 1 Hd2),
3.55 (s, 2 Hd1), 3.49 (t, J = 7.6 Hz, 1 Hd1), 3.11 (dd, J1 = 4.4 Hz, J2 = 11.2
Hz, 1 Hd2), 3.05–2.98 (m, 1 Hd2), 2.82–2.72 (m, 2 Hd1), 2.53–2.45 (m, 1
Hd2), 1.31–1.23 (m, 3 H).
13C NMR (100 MHz, CDCl3): δ = 163.9, 163.8, 137.9, 136.83, 136.76,
136.6, 132.2, 132.0, 129.7, 129.51, 129.47, 129.3, 128.69, 128.65,
127.73, 127.69, 122.6, 122.3, 85.8, 85.7, 63.3, 50.52, 49.5, 43.4, 43.3
35.1, 35.0, 13.9, 13.8.
HRMS: m/z [M + Na+] calcd for C17H16N2OSNa+: 319.0881; found:
319.0869.
Mixed Disulfides 14–19; General Procedure
HRMS: m/z [M + Na+] calcd for C19H20BrNO4S2Na+: 491.9915; found:
To a previously stirred solution (28 °C, 1.5 h) of tetrathiomolybdate 1
(0.731 g, 1.2 mmol) and disulfide 12 (0.8 mmol) in MeCN (10 mL) was
added the corresponding cyclopropane 13 (1.0 mmol). The reaction
mixture was then stirred for 2 h. The solvent was removed and the
residue was extracted with CH2Cl2 (5 mL) and Et2O (20 mL) and fil-
tered through a Celite pad. The residue was again extracted with
CH2Cl2 (5 mL) followed by extraction with Et2O (20 mL) and filtered
again through a Celite pad. The combined extracts were evaporated
and the residue was purified by column chromatography on silica gel
to give the corresponding mixed disulfide as an inseparable diastereo-
meric mixture.
491.9902.
Ethyl 4-[(4-Methylbenzyl)disulfanyl]-2-nitro-4-phenylbutanoate
(17)
Colorless liquid; yield: 0.203 g (55%) (40:60 dr).
IR (neat): 1754, 1564 cm–1
.
1H NMR (300 MHz, CDCl3 ): δ = 7.43–7.01 (m, 9 H), 5.21 (dd, J1 = 6.0
Hz, J2 = 8.1 Hz, 1 Hd1), 4.77 (dd, J1 = 3.9 Hz, J2 = 10.8 Hz, 1 Hd2), 4.29–
4.15 (m, 2 H), 3.65–3.55 (m, 1 Hd1 + 2 Hd2), 3.41 (s, 2 Hd1), 3.22 (dd, J1 =
4.2 Hz, J2 = 11.4 Hz, 1 Hd2), 3.10–3.00 (m, 1 Hd2), 2.94–2.72 (m, 2 Hd1),
2.62–2.32 (m, 1 Hd2), 2.37 (s, 3 Hd2), 2.34 (s, 3 Hd1), 1.32–1.22 (m, 3 H).
13C NMR (75 MHz, CDCl3): δ = 164.0, 137.5, 133.8, 129.34, 129.26,
129.0, 128.9, 128.6, 128.4, 128.2, 127.9, 86.0, 63.2, 50.9, 50.2, 44.0,
43.1, 35.2, 21.1, 13.8.
Ethyl 4-(Benzyldisulfanyl)-2-nitro-4-phenylbutanoate (14)
Colorless liquid; yield: 0.274 g (70%) (40:60 dr).
IR (neat): 1750, 1562, 1454 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.36–7.11 (m, 10 H), 5.19 (dd, J1 = 6.0
Hz, J2 = 8.0 Hz, 1 Hd1), 4..77 (dd, J1 = 4.0 Hz, J2 = 10.4 Hz, 1 Hd2), 4.31–
4.16 (m, 2 H), 3.68–3.59 (m, 2 Hd2 + 1 Hd1), 3.45 (s, 2 H), 3.24 (dd, J1 =
4.8 Hz, J2 = 11.6 Hz, 1 Hd2), 3.10–3.03 (m, 1 Hd2), 2.89–2.86 (m, 1 Hd1),
2.82–2.77 (m, 1 Hd1), 2.61–2.54 (m, 1 Hd2), 1.31–1.22 (m, 3 H).
13C NMR (100 MHz, CDCl3): δ = 163.98, 163.97, 138.8, 137.4, 136.9,
136.8, 129.5, 129.3, 129.1, 128.8, 128.6, 128.5, 128.4, 127.9, 127.6,
127.5, 85.9, 85.8, 63.2, 50.7, 50.1, 43.2, 43.1, 35.1, 34.8, 13.84, 13.79.
HRMS: m/z [M + Na] calcd for C20H23NO4S2Na+: 428.0966; found:
428.0965.
Ethyl 4-[(4-Chlorobenzyl)disulfanyl]-2-nitro-4-phenylbutanoate
(18)
Colorless liquid; yield: 0.320 g (75%) (40:60 dr).
IR (neat): 1749, 1564, 1250 cm–1
.
1H NMR (300 MHz, CDCl3): δ = 7.38–7.02 (m, 9 H), 5.21 (dd, J1 = 6.0
Hz, J2 = 8.4 Hz, 1 Hd1), 4.82 (dd, J1 = 4.2 Hz, J2 = 10.5 Hz, 1 Hd2), 4.30–
4.18 (m, 2 H), 3.67 (t, J = 7.8 Hz, 1 Hd1), 3.58 (d, J = 16.4 Hz, 1 Hd2), 3.52
(d, J = 16.8 Hz, 1 Hd2), 3.39–3.34 (m, 2 Hd1 + 1 Hd2), 3.12–3.02 (m, 1
Hd2), 2.91–2.80 (m, 2 Hd1), 2.65–2.55 (m, 1 Hd2), 1.32–1.23 (m, 3 H).
13C NMR (75 MHz, CDCl3): δ = 163.9, 138.8, 137.5, 135.3, 133.6, 130.7,
130.6, 129.2, 128.9, 128.8,128.7, 128.5, 128.1, 127.9, 85.9, 85.7, 63.3,
50.9, 50.4, 42.3, 42.2, 35.2, 34.9, 13.9, 13.8.
HRMS m/z [M + Na+] calcd for C19H21NO4S2Na+: 414.0810; found:
414.0800.
Ethyl 4-(Benzyldisulfanyl)-2-nitro-4-(p-tolyl)butanoate (15)
Colorless liquid; yield: 0.243 g (60%) (40:60 dr).
IR (neat): 1751, 1562, 1019 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.35–6.97 (m, 9 H), 5.14 (m, 1 Hd1),
4.46 (dd, J1 = 3.6 Hz, J2 = 10.8 Hz, 1 Hd2), 4.30–4.15 (m, 2 H), 3.69 (d, J =
12.6 Hz, 1 Hd1), 3.64 (d, J = 12.5 Hz, 1 Hd1), 3.56 (t, J = 8.0 Hz, 1 Hd1),
3.50 (s, 2 Hd1), 3.19 (dd, J1 = 4.4 Hz, J2 = 11.6 Hz, 1 Hd2), 3.10–3.02 (m, 1
Hd2), 2.89–2.87 (m, 1 Hd1), 2.79–2.73 (m, 1 Hd1), 2.57–2.50 (m, 1 Hd2),
2.35 (s, 3 Hd1), 2.33 (s, 3 Hd2), 1.31–1.23 (m, 3 H).
13C NMR (100 MHz, CDCl3): δ = 164.1, 138.6, 138.3, 137.0, 136.9,
134.2, 129.7, 129.53, 129.47, 129.4, 128.62, 128.55, 128.0, 127.8,
127.6, 127.5, 85.9, 85.8, 63.18, 63.15, 50.5, 49.7, 43.2, 35.1, 35.0, 21.2,
13.9, 13.8.
HRMS: m/z [M + Na] calcd for C19H20ClNO4S2Na+: 448.0420; found:
448.0421.
Ethyl 4-[(4-Methoxybenzyl)disulfanyl]-2-nitro-4-phenylbuta-
noate (19)
Colorless liquid; yield: 0.316 g (75%) (40:60 dr).
IR (neat): 1748, 1564, 1250 cm–1
.
1H NMR (300 MHz, CDCl3): δ = 7.39–7.05 (m, 7 H), 6.90–6.81 (m, 2 H),
5.22 (dd, J1 = 6.0 Hz, J2 = 8.4 Hz, 1 Hd1), 4.78 (dd, J1 = 3.9 Hz, J2 = 7.2 Hz,
1 Hd2), 4.31–4.16 (m, 2 H), 3.83 (s, 3 Hd2), 3.80 (s, 3 Hd1), 3.66 (m, 2 Hd2
+ 1 Hd1), 3.41 (s, 2 Hd1), 3.24 (dd, J1 = 4.2 Hz, J2 = 11.4 Hz, 1 Hd2), 3.11–
3.01 (m, 1 Hd2), 2.94–2.73 (m, 2 Hd1), 2.62–2.52 (m, 1 Hd2), 1.32–1.23
(m, 3 H).
HRMS: m/z [M + Na+] calcd for C20H23NO4S2Na+: 428.0966; found:
428.0966.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–J

I
P. Gopinath, S. Chandrasekaran
Paper
Synthesis
13C NMR (75 MHz, CDCl3): δ = 164.02, 163.97, 159.2, 159.1, 138.9,
137.6, 130.6, 130.5, 129.0, 128.8, 128.7, 128.6, 128.3, 128.1, 127.9,
114.04, 113.96, 86.0, 85.8, 63.2, 55.29, 55.27, 50.7, 50.0, 42.7, 35.1,
34.9, 13.80, 13.78.
HRMS: m/z [M + Na] calcd for C20H23NO5S2Na+: 444.0915; found:
444.0914.
1,2-Bis[1-(4-bromophenyl)-3-nitropropyl]disulfane (24c)
Colorless liquid; yield: 0.138 g (50%) (50:50 dr).
IR (neat): 1552, 1513 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.52–7.49 (m, 4 H), 7.04–6.99 (m, 4 H),
4.36–4.30 (m, 2 H), 4.22–4.15 (m, 2 H), 3.42–3.38 (m, 2 H), 2.72–2.63
(m, 2 H), 2.41–2.35 (m, 2 H).
13C NMR (100 MHz, CDCl3): δ = 137.8, 132.8, 132.7, 130.1, 130.0,
123.1, 73.24, 73.19, 51.4, 51.2, 32.44, 32.36.
Mixed Disulfide 14 from Benzyl Bromide (20)
To a well stirred solution of benzyl bromide (20; 0.274 g, 1.6 mmol) in
MeCN was added tetrathiomolybdate 1 (1.705 g, 2.8 mmol) in MeCN
(4 mL) and the mixture was stirred for 1.5 h. To this was added nitro-
cyclopropane 13a (0.235 g, 1.0 mmol) and the reaction mixture was
again stirred for 2 h at r.t. (28 °C). After the completion of reaction,
the solvent was removed and Et2O (20 mL) was added to it and fil-
tered through a Celite pad. The residue was again extracted with
CH2Cl2 (5 mL) followed by extraction with Et2O (20 mL) and filtered
again through a Celite pad. The combined extracts were evaporated
and the residue was purified by column chromatography on silica gel
to give compound 14 as a colorless liquid; yield: 0.196 g (50%).
HRMS: m/z [M + Na] calcd for C18H18Br2N2O4S2Na+: 570.8972; found:
570.8973.
(4-Chlorophenyl)(3-nitro-1-phenylpropyl)sulfane (25)
To a well stirred solution of cyclopropane derivative 21a (0.229 g, 1.0
mmol) in CHCl3 (10 mL) were added PPh3 (0.288 g, 1.1 mmol) and NBS
(0.196 g, 1.1 mmol). After stirring the reaction mixture for 15 min, a
mixture of p-chlorodiphenyl disulfide (2a; 0.230 g, 0.8 mmol) and
tetrathiomolybdate 1 (0.609 g, 1.0 mmol), previously stirred for 1.5 h,
was added. After the completion of reaction (2.5 h, 28 °C), solvent was
removed and Et2O (30mL) was added and filtered through a Celite
pad. The residue was again extracted with CH2Cl2 (5 mL) followed by
extraction with Et2O (20 mL) and filtered again through a Celite pad.
The combined extracts were evaporated and the residue was purified
by column chromatography on silica gel to give compound 25 as a col-
orless liquid; yield: 0.194 g (63%).
Disulfides 24a–c; General Procedure
Cyclopropane derivative 21 (1.0 mmol) was stirred together with
PPh3 (0.288 g, 1.1 mmol) and NBS (0.196 g, 1.1 mmol) in CHCl3 (10
mL) for 15 min. Tetrathiomolybdate 1 (0.609 g, 1.0 mmol) was then
added to the reaction mixture and stirring continued for 3 h. Et2O (30
mL) was then added to the reaction mixture followed by filtration
through a Celite pad. The residue was again extracted with CH2Cl2 (5
mL) followed by extraction with Et2O (20 mL) and filtered again
through a Celite pad. The combined extracts were evaporated and the
residue was purified by column chromatography on silica gel to give
the corresponding disulfide as an inseparable diastereomeric mix-
ture.
IR (neat): 1550, 1089 cm–1
.
1H NMR (300 MHz, CDCl3): δ = 7.31–7.18 (m, 9 H), 4.51–4.14 (m, 2 H).
3.99 (dd, J1 = 6.0 Hz, J2 = 9.6 Hz, 1 H), 2.95–2.83 (m, 1 H), 2.66–2.49 (m,
1 H).
13C NMR (75 MHz, CDCl3): δ = 137.8, 135.2, 133.3, 129.1, 128.9, 128.6,
128.0, 127.8.
HRMS: m/z [M + Na] calcd for C15H14ClNO2SNa+: 330.0331; found:
330.0328.
1,2-Bis(3-nitro-1-phenylpropyl)disulfane (24a)
Colorless liquid; yield: 0.153 g (70%) (50:50 dr).
Ethyl 4-(Benzoylthio)-2-nitro-4-phenylbutanoate (27)
IR (neat): 1552, 1380 cm–1
.
To a well-stirred solution of benzoic acid (26; 0.146 g, 1.2 mmol), PPh3
(0.341 g, 1.3 mmol), and NBS (0.231 g, 1.3 mmol) in CHCl3 (10 mL)
(stirred for 15 min) was added benzyltriethylammonium tetrathio-
molybdate 1 (0.731 g, 1.2 mmol). The cyclopropane derivative 13a
(0.235 g, 1.0 mmol) was then added after 20 min and stirred at r.t. for
5 h. Et2O (30 mL) was then added to the reaction mixture followed by
filtration through Celite pad. The residue was again extracted with
CH2Cl2 (5 mL) followed by extraction with Et2O (20 mL) and filtered
again through a Celite pad. The combined extracts were evaporated
and the residue was purified by column chromatography on silica gel
to give compound 27 as a colorless liquid in a 1:1 diastereomeic ratio;
yield: 0.224 g (70%) (based on the recovery of starting material).
1H NMR (300 MHz, CDCl3): δ = 7.37–7.35 (m, 6 H), 7.19–7.12 (m, 4 H),
4.39–4.23 (m, 2 H), 4.21–4.12 (m, 2 H), 3.39–3.33 (m, 2 H). 2.78–2.66
(m, 2 H), 2.48–2.38 (m, 2 H).
13C NMR (75 MHz, CDCl3): δ = 138.4, 129.1, 129.0, 128.6, 128.59,
128.55, 128.0, 127.9, 73.0, 72.9, 51.3, 50.9, 31.9, 31.6.
HRMS: m/z [M + Na] calcd for C18H20N2O4S2Na+: 415.0762; found:
415.0743.
1,2-Bis[3-nitro-1-(p-tolyl)propyl]disulfane (24b)
Colorless liquid; yield: 0.126 g (60%) (50:50 dr).
IR (neat): 1552 cm–1
.
IR (neat): 1748, 1666, 1564, 1206 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.23–7.16 (m, 4 H), 7.09–6.97 (m, 4 H),
4.31–4.23 (m, 2 H), 4.17–4.12 (m, 2 H), 3.40–3.35 (m, 2 H), 2.74–2.65
(m, 2 H), 2.41–2.37 (m, 8 H).
13C NMR (100 MHz, CDCl3): δ = 138.6, 138.5, 135.3, 129.70, 129.68,
127.9, 127.8, 73.1, 73.0, 51.0, 50.7, 32.0, 31.7, 21.1.
1H NMR (300 MHz, CDCI3): δ = 7.94–7.90 (m, 2 H), 7.60–7.46 (m, 1 H),
7.44–7.31 (m, 1 H), 5.17 (dd, J1 = 6.0 Hz, J2 = 8.1 Hz, 1 Hd1), 5.01 (dd,
J1 = 5.4 Hz, J2 = 9.0 Hz, 1 Hd2), 4.92–4.87 (m, 1 Hd1), 4.81 (dd, J1 = 6.6
Hz, J2 = 9.3 Hz, 1 Hd2), 4.37–4.21 (m, 2 H), 3.11–2.98 (m, 1 H), 2.93–
2.81 (m, 1 H), 1.35–1.25 (m, 3 H).
HRMS: m/z [M + Na] calcd for C20H24N2O4S2Na+: 443.1075; found:
443.1071.
13C NMR (75 MHz, CDCl3): δ = 189.8, 164.2, 163.9, 139.4, 138.8, 136.4,
133.8, 129.2, 129.1, 128.7, 128.4, 128.3, 127.9, 127.7, 127.5, 127.4,
86.0, 85.6, 63.3, 63.2, 44.4, 37.0, 36.9, 13.9, 13.8.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–J

J
P. Gopinath, S. Chandrasekaran
Paper
Synthesis
HRMS: m/z [M + Na] calcd for C19H19NO5SNa+: 396.0882; found:
396.0874.
(9) (a) Parker, A. J.; Kharasch, N. Chem. Rev. 1959, 59, 583. (b) Gorin,
G.; Dougherty, G.; Tobolsky, A. V. J. Am. Chem. Soc. 1949, 71,
3551.
(10) (a) Blanchard, L. A.; Schneider, J. A. J. Org. Chem. 1986, 51, 1372.
(b) Stewart, J. M.; Westberg, H. H. J. Org. Chem. 1965, 30, 1951.
(c) Wurz, R. P.; Carette, A. B. Org. Lett. 2005, 7, 2313. (d) Lifchits,
O.; Alberico, D.; Zakharian, I.; Charette, A. B. J. Org. Chem. 2008,
73, 6838. (e) Lebold, T. P.; Kerr, M. A. Org. Lett. 2009, 11, 4354.
(f) Lifchits, O.; Charette, A. B. Org. Lett. 2008, 10, 2809.
(g) Danishefsky, S. Acc. Chem. Res. 1979, 12, 66. (h) Dolfini, J. E.;
Menich, K.; Corliss, P. Tetrahedron Lett. 1966, 37, 4421.
(i) Reissig, H.-U.; Zimmer, R. Chem. Rev. 2003, 103, 1151.
(j) Schneider, T. F.; Kaschel, J.; Werz, D. B. Angew. Chem. Int. Ed.
2014, 53, 5504. (k) Yu, M.; Pagenkopf, B. L. Tetrahedron 2003, 59,
2765. (l) Garve, L. K. B.; Pawliczek, M.; Wallbaum, J.; Jones, P. G.;
Werz, D. B. Chem. Eur. J. 2016, 22, 521.
(11) Jonsson, S. Y.; Lofstrom, C. M. G.; Backvall, J. E. J. Org. Chem.
2000, 65, 8454.
(12) Gopinath, P.; Chandrasekaran, S. J. Org. Chem. 2011, 76, 700.
(13) Gopinath, P.; Chandrakala, R. N.; Chandrasekaran, S. Synthesis
2015, 47, 1488.
(14) Prabhu, K. R.; Devan, N.; Chandrasekaran, S. Synlett 2002, 1762.
(15) (a) Pan, W. H.; Harmer, M. A.; Halbert, T. R.; Stiefel, E. I. J. Am.
Chem. Soc. 1984, 106, 459. (b) Prabhu, K. R.; Sivanand, P.;
Chandrasekaran, S. Angew. Chem. Int. Ed. 2000, 39, 4316.
(16) Sureshkumar, D.; Ganesh, V.; Vidyarini, R. S.; Chandrasekaran, S.
J. Org. Chem. 2009, 74, 7958.
Acknowledgment
P.G. thanks CSIR, New Delhi, for a Senior Research Fellowship, and
S.C.N. thanks DST New Delhi for a SERB Distinguished Fellowship.
Supporting Information
Supporting information for this article is available online at
http://dx.doi.org/10.1055/s-0035-1561629.
S
u
p
p
ortioInfgrmoaitn
S
u
p
p
ortiInfogrmoaitn
References
(1) Cremlyn, R. J. An Introduction to Organosulfur Chemistry; Wiley:
Chichester, 1996.
(2) (a) Fluharty, A. L. In The Chemistry of the Thiol Group; Patai, S.,
Ed.; Wiley Interscience: New York, 1974, Part 2; 589. (b) Trost,
B. M.; Keeley, D. E. J. Org. Chem. 1975, 40, 2013. (c) Kumar, A.;
Salunkhe, R. V.; Rane, R. A.; Dike, S. Y. J. Chem. Soc., Chem.
Commun. 1991, 485.
(3) Sevier, C. S.; Kaiser, C. A. Nat. Rev. Mol. Cell Biol. 2002, 3, 836.
(4) (a) Smith, M. B.; March, J. March’s Advanced Organic Chemistry,
6th ed.; Wiley: Hoboken, 2007. (b) Yin, J.; Pidegon, C. Tetrahe-
dron Lett. 1997, 38, 5953.
(5) (a) Itoh, T.; Mase, T. Org. Lett. 2004, 6, 4587. (b) Bates, C. G.;
Gujadhur, R. K.; Venkataraman, D. Org. Lett. 2002, 4, 2803.
(c) Murata, M.; Buchwald, S. L. Tetrahedron 2004, 60, 7397.
(d) Li, G. Y. Angew. Chem. Int. Ed. 2001, 40, 1513. (e) Ogawa, A.;
Ikeda, T.; Kimura, K.; Hirao, T. J. Am. Chem. Soc. 1999, 121, 5108.
(6) Firouzabadi, H.; Iranpoor, N.; Jafarpour, M.; Ghaderi, A. J. Mol.
Catal. A: Chem. 2006, 249, 98.
(17) Ramesha, A. R.; Chandrasekaran, S. Synth. Commun. 1992, 22,
3277.
(18) (a) Froyen, P. Phosphorus Sulfur and Silicon 1994, 89, 57.
(b) Froyen, P. Phosphorus Sulfur and Silicon 1994, 91, 145.
(c) Froyen, P. Synth. Commun. 1995, 25, 959. (d) Sucheta, K.;
Reddy, G. S. R.; Ravi, D.; Rama Rao, N. Tetrahedron Lett. 1994, 35,
4415.
(19) (a) Gopinath, P.; Vidyarini, R. S.; Chandrasekaran, S. J. Org. Chem.
2009, 74, 6291. (b) Gopinath, P.; Vidyarini, R. S.;
Chandrasekaran, S. Eur. J. Org. Chem. 2009, 6043. (c) Gopinath,
P.; Debasree, C.; Vidyarini, R. S.; Chandrasekaran, S. Tetrahedron
2010, 66, 7001.
(20) Wurz, R. P.; Charette, A. B. Org. Lett. 2003, 5, 2327.
(21) O’Bannon, P. E.; Dailey, W. P. J. Org. Chem. 1990, 55, 353.
(22) Pryor, W. A.; Church, D. F.; Govindan, C. K.; Crank, G. J. Org.
Chem. 1982, 47, 156.
(23) Krishnamurthy, S.; Aimino, D. J. Org. Chem. 1989, 54, 4458.
(24) Oae, S.; Yamada, N.; Fujimori, K.; Kikuchi, O. Bull. Chem. Soc. Jpn.
1983, 56, 248.
(7) Chelucci, G.; Culeddu, N.; Saba, A.; Valenti, R. Tetrahedron:
Asymmetry 1999, 10, 3537.
(8) (a) Wardell, J. L.; Clarke, P. L. J. Organomet. Chem. 1971, 26, 345.
(b) Harpp, D. N.; Friedlander, B. T.; Larsen, C.; Steliou, K.;
Stockton, A. J. Org. Chem. 1978, 43, 3481. (c) Brown, C.; Evans, G.
R. Tetrahedron Lett. 1996, 37, 9101. (d) Capozzi, G.; Capperucci,
A.; Degl’Innocenti, A.; Del Duce, R.; Menichetti, S. Tetrahedron
Lett. 1989, 30, 2995. (e) Rajca, A.; Wiessler, M. Tetrahedron Lett.
1990, 31, 6075. (f) Hiver, P.; Dicko, A.; Paquer, D. Tetrahedron
Lett. 1994, 35, 9569. (g) Harpp, D. H.; Ash, D. K.; Back, T. G.;
Gleason, J. G.; Orwig, B. A.; VanHorn, W. F.; Snyder, J. P. Tetrahe-
dron Lett. 1970, 11, 3551. (h) Boustang, K. S.; Sullivan, A. B. Tet-
rahedron Lett. 1970, 3547.
(25) Xiao, H.; Chen, J.; Liu, M.; Wu, H.; Ding, J. Phosphorus Sulfur and
Silicon 2009, 184, 2553.
(26) Zeynizadeh, B. J. Chem. Res., Synop. 2002, 564.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–J