One-Pot Synthesis of Sulfonamides from Sodium Sulfinates and Amines via Sulfonyl Bromides

Article abstract of DOI:10.1055/s-0036-1588298

a new and convenient procedure has been developed for the preparation of sulfonamides from sodium sulfinates and amines with (n-C₄H₉)₄NBr as bromine source and m-chloroperbenzoic acid as oxidant. This S-N bond formation reaction proceeds efficiently via sulfonyl bromides under neutral conditions to afford the corresponding sulfonamides in good yields at room temperature.

Full text of DOI:10.1055/s-0036-1588298

SYNLETT
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© Georg Thieme Verlag Stuttgart · New York
2016, 27, A–F
letter
A
S. Wu et al.
Letter
Synlett
One-Pot Synthesis of Sulfonamides from Sodium Sulfinates and
Amines via Sulfonyl Bromides
Sixue Wua
Yikun Zhanga
Min Zhub
O
S
O
S
R2
R3
R2
R3
(n-C4H9)4NBr, m-CPBA
R1
N
R1
ONa
N
H
+
THF/MeOH (30:1), r.t., 12 h
O
16 examples
up to 89% yield
Jie Yan*a
a College of Chemical Engineering, Zhejiang University
of Technology, Hangzhou 310032, P. R. of China
jieyan87@zjut.edu.cn
b College of Biological and Environmental Sciences,
Zhejiang Shuren University, Hangzhou 310015, P. R.
of China
Received: 25.06.2016
Accepted after revision: 31.07.2016
Published online: 22.08.2016
The catalytic utilization of molecular iodine and its salts
in organic synthesis is increasing in importance, with grow-
ing interest in the development of environmentally benign
synthetic transformations.6 Due to the ease of handling, low
toxicity, commercial availability, and mild reactivity, espe-
cially the metal-like behavior of iodine, a number of recent
studies have demonstrated the utility of iodine catalysis as
an efficient and powerful tool for the formation of carbon–
carbon and carbon–heteroatom bonds.7 Using iodine as the
catalyst, the construction of carbon–sulfur bond methods
also have been developed from sodium sulfinates.8 Very re-
cently, the iodine-mediated or iodine-catalyzed one-pot
synthesis of sulfonamides from readily available sodium
sulfinates and amines has been reported, which is demon-
strated via sulfonyl iodide intermediates (Scheme 1).9 It is
very interesting because this nitrogen–sulfur bond-forma-
tion method is general, efficient, and environmentally
friendly. To extend the application scope of this methodolo-
gy, we have investigated a similar route for the synthesis of
sulfonamides via sulfonyl bromide intermediates. Fortu-
nately, a new and convenient procedure has been developed
for accessing sulfonamides from sodium sulfinates and
amines, which is promoted by (n-C4H9)4NBr combined with
oxidant m-chloroperbenzoic acid (m-CPBA, Scheme 1). To
the best of our knowledge, this method has not been re-
ported before.
DOI: 10.1055/s-0036-1588298; Art ID: st-2016-w0411-l
Abstract a new and convenient procedure has been developed for the
preparation of sulfonamides from sodium sulfinates and amines with
(n-C4H9)4NBr as bromine source and m-chloroperbenzoic acid as oxi-
dant. This S–N bond formation reaction proceeds efficiently via sulfonyl
bromides under neutral conditions to afford the corresponding sulfon-
amides in good yields at room temperature.
Key words sulfonamides, sodium sulfinates, amines, (n-C4H9)4NBr,
sulfonyl bromides
Sulfonamides are very important organic compounds
and have been broadly applied in pharmaceutical industry
due to their effective antifungal, anticancer, antibacterial,
antipsychotic anticonvulsant, and HIV protease inhibitory
activities.1 They are also used as nitrogen protecting groups
in organic synthesis.2 The traditional method for the forma-
tion of sulfonamides is by the nucleophilic reaction of ami-
no compounds on sulfonyl chlorides in the presence of a
base.3 However, this method has some limitations, such as
hazardous starting materials, harsh reaction conditions,
and the difficulty to obtain some sulfonyl chlorides. To ob-
viate these drawbacks, alternative methods have been de-
veloped, including the metal-catalyzed coupling reaction of
sulfonamides with organic halides, arylboronic acids, alco-
hols, or hydrocarbons4 and copper-catalyzed oxidative cou-
pling of amines and sodium sulfinates.5 Nevertheless, the
above methods for the preparation of sulfonamides usually
use transition-metal catalysts and toxic solvents as reaction
media, which might increase the risk or cause pollution in
the final products. In addition, some of them also suffer
from hardly available reactants, multistep reactions, com-
plex reaction conditions, high reaction temperatures, and
long reaction times.
Previous work:
O
O
R2
R3
R2
R3
I2
R1
S
N
R1
S ONa
N H
O
This work:
O
S
O
R2
R3
R2
(n-C4H9)4NBr
m-CPBA
R1
N
R1
S ONa
N H
R3
O
Scheme 1 Methods for the synthesis of sulfonamides
© Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–F

B
S. Wu et al.
Letter
Synlett
Although similar to iodine, molecular bromine is diffi-
cult to handle due to its strong volatility and corrosiveness.
Using sodium bromide (NaBr) combined with m-CPBA to
replace bromine, we first explored the one-pot procedure
for the preparation of sulfonamides from sodium benzene-
sulfinate (1a) and benzylamine (2a) at room temperature.
We were pleased to find that simply stirring of a mixture of
2.0 equivalents of 1a with 1.0 equivalent of 2a, NaBr and
m-CPBA in CH2Cl2 for 12 hours, the desired product, N-ben-
zylbenzenesulfonamide (3a) was obtained, albeit in 26%
yield (Table 1, entry 1). Then, the reaction conditions were
optimized. Among various solvents screened, tetrahydrofu-
ran (THF) led to the best yield, 47%, for 3a (Table 1, entries
1–9). Due to the bad solubility of 1a in THF, water was add-
ed to improve the reaction. The experiment indicated that
when the volume ratio of THF to H2O was 30:1, the mixed
solvent was not beneficial to the reaction. However, using
MeOH to replace H2O, the yields increased, and finally the
mixed solvent THF–MeOH (30:1) was selected as a suitable
solvent for the reaction (Table 1, entries 10–13). In this sol-
Table 1 Optimization of the Reaction Conditions for the Preparation of N-Benzylbenzenesulfonamide
O
Br–, m-CPBA
H
S
N
PhSO2Na
PhCH2NH2
solvent, r.t., 12 h
O
1a
2a
3a
Entry
PhSO2Na (equiv)
m-CPBA (equiv)
Br– (equiv)
Solvent
Yield (%)a
1
2
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
1.8
1.5
1.2
1.5
1.5
1.0
NaBr (1.0)
NaBr (1.0)
NaBr (1.0)
NaBr (1.0)
NaBr (1.0)
NaBr (1.0)
NaBr (1.0)
NaBr (1.0)
NaBr (1.0)
NaBr (1.0)
NaBr (1.0)
NaBr (1.0)
NaBr (1.0)
KBr (1.0)
CH2Cl2
26
35
38
–
1.0
MeCN
3
1.0
EtOAc
4
1.0
H2O
5
1.0
TFA
30
32
47
35
44
45
76
56
50
69
72
83
–
6
1.0
MeOH
7
1.0
THF
8
1.0
DCE
9
1.0
1,4-dioxane
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
1.0
THF–H2O (30:1)
THF–MeOH (30:1)
THF–MeOH (20:1)
THF– MeOH (10:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
THF–MeOH (30:1)
1.0
1.0
1.0
1.0
1.0
NH4Br (1.0)
1.0
(n-C4H9)4NBr (1.0)
THBP (1.0)
H2O2 (1.0)
K2S2O8 (1.0)
1.2
(n-C4H9)4NBr (1.0)
(n-C4H9)4NBr (1.0)
(n-C4H9)4NBr (1.0)
(n-C4H9)4NBr (1.0)
(n-C4H9)4NBr (1.0)
(n-C4H9)4NBr (1.0)
(n-C4H9)4NBr (1.2)
(n-C4H9)4NBr (0.8)
(n-C4H9)4NBr (0.2)
(n-C4H9)4NBr (1.2)
(n-C4H9)4NBr (1.2)
(n-C4H9)4NBr (1.2)
(n-C4H9)4NBr (1.2)
–
–
12
82
78
70
86
80
30
86
86
80
–
1.3
1.5
1.0
1.0
1.0
1.0
1.0
1.0
–
1.0
–
a Isolated yields.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–F

C
S. Wu et al.
Letter
Synlett
vent mixture, other bromides such as KBr, NH4Br, and
(n-C4H9)4NBr were examined. Among them, (n-C4H9)4NBr
was the most efficient with regard to the yield of 3a, and
1.2 equivalents of it was the optimized amount (Table 1, en-
tries 11, 14–16, 23–25). Compared with m-CPBA, other oxi-
dants such as tert-butyl hydroperoxide (TBHP), hydrogen
peroxide (H2O2), and dipotassium persulfate (K2S2O8) were
not active in the reaction or resulted in lower yield of 3a.
Therefore, m-CPBA was the most suitable oxidant and the
optimized amount of it was also determined (Table 1, en-
tries 16–22). In addition, the quantity of sodium benzene-
sulfinate was optimized: 1.5 equivalents of it was the best
choice (Table 1, entries 23, 26–28). Under the optimized
conditions, the reaction proceeded smoothly and was com-
pleted in 12 hours. The control experiment also indicated
that in the absence of m-CPBA or (n-C4H9)4NBr, no desired
product was obtained (Table 1, entries 29 and 30).
O
S
O
S
R2
R2
R3
(n-C4H9)4NBr, m-CPBA
R1
N
R1
ONa
N
H
R3
2a–h
THF/MeOH (30:1), r.t. 12 h
O
3a–p
1a–b
Scheme 2 Preparation of sulfonamides 3 from sodium sulfinates 1 and
amines 2 promoted by (n-C4H9)4NBr
Based on the extensive screening process, we arrived at
the optimal reaction conditions (Scheme 2). Then, with 1.5
equivalents of sodium sulfinates 1, 1.0 equivalent of amines
2 and m-CPBA in the presence of 1.2 equivalents of
(n-C4H9)4NBr, the one-pot reaction proceeded smoothly in
THF–MeOH (30:1) at room temperature, and after 12 hours
a series of the corresponding sulfonamides 3 were ob-
tained.10 The results are summarized in Table 2.
Table 2 Preparation of Sulfonamides 3 from Sodium Sulfinates 1 and Amines 2 Promoted by (n-C4H9)4NBr
Entry
1
Sodium sulfinates 1
PhSO2Na 1a
Amines 2
Products 3
Yield (%)a
86
O
NH2
S
NH
NH
NH
NH
O
2a
3a
3b
3c
O
NH2
S
2
3
4
1a
1a
1a
89
72
55
OMe
O
MeO
2b
O
S
NH2
Cl
O
Cl
2c
O
S
NH2
N
N
O
2d
3d
3e
3f
O
S
NH2
NH
N
5
6
7
8
1a
1a
1a
1a
63
78
58
45
O
2e
O
S
O
NH
O
O
2f
O
S
NH
N
O
2g
2h
3g
3h
O
S
NH
N
O
© Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–F

D
S. Wu et al.
Letter
Synlett
Table 2 (continued)
Entry
Sodium sulfinates 1
Amines 2
Products 3
Yield (%)a
81
O
S
NH
NH
SO2Na
9
2a
O
1b
1b
3i
O
S
10
11
12
2b
2c
2d
84
70
50
O
OMe
3j
O
S
NH
NH
1b
1b
Cl
O
3k
O
N
S
O
3l
O
S NH
O
13
14
15
16
1b
1b
1b
1b
2e
2f
62
72
54
39
3m
3n
3o
3p
O
S
N
N
N
O
O
O
S
2g
2h
O
O
S
O
a Isolated yields.
As shown in Table 2, the one-pot reaction was compati-
ble with the studied primary and secondary amines when
sodium sulfinates 1a and 1b were treated, affording the
corresponding sulfonamides 3 in moderate to excellent
yields (Table 2, entries 1–16). It is obvious that sodium ben-
zenesulfinate 1a had a better effect in the reaction than so-
dium p-tolylsulfinate (1b). In a similar manner, when sodi-
um methylsulfinate, an aliphatic sodium sulfinate, was
used to replace 1a or 1b, the one-pot reaction nearly did
not proceed, in agreement with Wei’s report.9c The results
also demonstrated that amine 2b, bearing an electron-do-
nating group on benzene ring, usually resulted in the prod-
ucts with higher yields than 2c and 2d, those having elec-
tron-withdrawing groups on aromatic rings (Table 2, en-
tries 2–4, 10–12). Among three secondary amines, both
cyclic amines 2f and 2g gave the corresponding products in
moderate to good yields; while as a representative of acyclic
amines, 2h normally let to the products in somewhat low
yields (Table 2, entries 6–8, 14–16).
When radical scavenger, 2,2,6,6-tetramethyl-piperi-
dine1-oxyl (TEMPO), was added in the reaction of sodium
benzenesulfinate (1a) and benzylamine (2a) under the op-
timized reaction conditions, the one-pot reaction still pro-
ceeded well, resulting in the product 3a in good yield. This
result suggests that the mechanism may undergo a nucleo-
philic substitution pathway. A plausible mechanism for the
preparation of sulfonamides is depicted in Scheme 3. Ini-
tially, (n-C4H9)4NBr is oxidized by m-CPBA into molecular
bromine that reacts with sodium sulfinate immediately to
form the active sulfonyl bromide.11 Then, the in situ gener-
ated sulfonyl bromide intermediate is attacked by the nuc-
leophilic amine, affording the desired product sulfonamide.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–F

E
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Letter
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Eur. J. Org. Chem. 2013, 858. (e) Zeng, L. Y.; Yi, W. B.; Cai, C. Eur. J.
Org. Chem. 2012, 559. (f) Froehr, T.; Sindlinger, C. P.; Kloeckner,
U.; Finkbeiner, P.; Nachtsheim, B. J. Org. Lett. 2011, 13, 3754.
(g) Lamani, M.; Prabhu, K. R. J. Org. Chem. 2011, 76, 7938.
(h) Yuan, Y.; Ji, X.; Zhao, D. Eur. J. Org. Chem. 2010, 5274.
(i) Reddy, K. R.; Maheswari, C. U.; Venkateshwar, M.; Kantam, M.
L. Eur. J. Org. Chem. 2008, 3619. (j) Liotta, D. Acc. Chem. Res.
1984, 17, 28.
O
S
R2R3NH
R1SO2Na
R2
R3
m-CPBA
R1SO2Br
R1
N
(n-C4H9)4NBr
Br2
O
Scheme 3 Proposed mechanism for the preparation of sulfonamides
In summary, we have developed a now and convenient
procedure for the preparation of sulfonamides from sodium
sulfinates and amines in the presence of (n-C4H9)4NBr and
m-CPBA at room temperature in air. This one-pot reaction
has some advantages such as readily available starting ma-
terials, mild reaction conditions, simple procedure, and
good yields. Furthermore, the one-pot reaction via sulfonyl
bromides under neutral conditions will extend the applica-
tion scope of molecular iodine in organic synthesis.
(8) (a) Lin, Y.-M.; Lu, G.-P.; Cai, C.; Yi, W.-B. Org. Lett. 2015, 17,
3310. (b) Kariya, A.; Yamaguchi, T.; Nobuta, T.; Tada, N.; Miura,
T.; Itoh, A. RSC Adv. 2014, 4, 13191. (c) Katrun, P.; Hongthong, S.;
Hlekhlai, S.; Pohmakotr, M.; Reutrakul, V.; Soorukram, D.;
Jaipetch, T.; Kuhakarn, C. RSC Adv. 2014, 4, 18933. (d) Gao, W.-
C.; Zhao, J.-J.; Hu, F.; Chang, H.-H.; Li, X.; Wei, W.-L. RSC Adv.
2015, 5, 25222. (e) Katrun, P.; Mueangkaew, C.; Pohmakotr, M.;
Reutrakul, V.; Jaipetch, T.; Soorukram, D.; Kuhakarn, C. J. Org.
Chem. 2014, 79, 1778. (f) Xiao, F.-H.; Chen, H.; Xie, H.; Chen, S.-
Q.; Yang, L.; Deng, G.-J. Org. Lett. 2014, 16, 50. (g) Xiao, F.-H.; Xie,
H.; Liu, S.-W.; Deng, G.-J. Adv. Synth. Catal. 2014, 356, 364.
(9) (a) Yang, K.; Ke, M.; Lin, Y.-G.; Song, Q.-L. Green Chem. 2015, 17,
1395. (b) Pan, X.-J.; Gao, J.; Liu, J.; Lai, J.-Y.; Jiang, H.-F.; Yuan, G.-
Q. Green Chem. 2015, 17, 1400. (c) Wei, W.; Liu, C.-L.; Yang, D.-
S.; Wen, J.-W.; You, J.-M.; Wang, H. Adv. Synth. Catal. 2015, 357,
987. (d) Chonchanok, B.; Danupat, B.; Sirilata, Y. Eur. J. Org.
Chem. 2015, 1575. (e) Zhao, J.-W.; Xu, J.-X.; Chen, J.-X.; Wang,
X.-Q.; He, M.-H. RSC Adv. 2014, 4, 64698.
(10) A Typical Procedure for the Preparation of Sulfonamides
In mixed solvent THF–MeOH (30:1, 2.0 mL), sodium sulfinates 1
(0.45 mmol), amines 2 (0.30 mmol), (n-Bu)4NBr (0.36 mmol),
and m-CPBA (0.3 mmol) were added successively. The suspen-
sion mixture was vigorously stirred at r.t. for 12 h. Upon com-
pletion, the reaction was quenched by addition of sat. aq
Na2S2O3 (2 mL), sat. aq Na2CO3 (8 mL), and H2O (5 mL), respec-
tively. The mixture was extracted with CH2Cl2 (3 × 5 mL) and
the combined organic phase was dried over anhydrous Na2SO4,
filtered, and concentrated under reduced pressure. The residue
was then purified on a silica gel plate (PE–EtOAc = 3:1) to
furnish products 3.
References and Notes
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N-Benzylbenzenesulfonamide (3a)
White solid; mp 82–83 °C (lit.12 85–87 °C). IR (KBr): 3329, 1326,
1162, 1093, 1061, 750, 687 cm–1. 1H NMR (500 MHz, CDCl3): δ =
7.86 (d, J = 7.2 Hz, 2 H), 7.59–7.54 (m, 1 H), 7.50–7.45 (m, J = 7.7
Hz, 2 H), 7.27–7.21 (m, 3 H), 7.20–7.16 (m, 2 H), 5.43 (t, J = 6.1
Hz, 1 H), 4.12 (d, J = 6.3 Hz, 2 H). 13C NMR (125 MHz, CDCl3): δ =
139.8, 136.2, 132.5, 129.0, 128.5, 127.7, 127.6, 126.9, 47.0. ESI-
MS: m/z (%) = 265 (100) [M + NH4]+.
N-(4-Methoxybenzyl)benzenesulfonamide (3b)
White solid; mp 71–72 °C (lit.13 72–75°C). IR (KBr): 3281, 1513,
1321, 1254, 1158, 1091, 1031, 858, 730, 685, 590 cm–1. 1H NMR
(500 MHz, CDCl3): δ = 7.85–7.81 (m, 2 H), 7.57–7.52 (m, 1 H),
7.47 (t, J = 7.7 Hz, 2 H), 7.08 (d, J = 8.6 Hz, 2 H), 6.75 (d, J = 8.7 Hz,
2 H), 5.38 (t, J = 6.1 Hz, 1 H), 4.04 (d, J = 6.1 Hz, 2 H), 3.73 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 159.0, 139.8, 132.4, 129.1, 128.9,
128.2, 126.9, 113.8, 55.1, 46.5. ESI-MS: m/z (%) = 295 (100) [M + NH4]+.
4-(Phenylsulfonyl)morpholine (3f)
(5) (a) Tang, X.; Huang, L.; Qi, C.; Wu, X.; Wu, W.; Jiang, H. Chem.
Commun. 2013, 49, 6102. (b) Moon, S.-Y.; Nam, J.; Rathwell, K.;
Kim, W.-S. Org. Lett. 2014, 16, 338. (c) Huang, X.; Wang, J.; Ni, Z.;
Wang, S.; Pan, Y. Chem. Commun. 2014, 4582.
White solid; mp 107–108 °C (lit.14 117–119 °C). IR (KBr): 2979,
2862, 1450, 1347, 1261, 1168, 1109, 943, 746, 693, 579, 532
1
cm–1. H NMR (500 MHz, CDCl3): δ = 7.78–7.73 (m, 2 H), 7.66–
(6) Finkbeiner, P.; Nachtsheim, B. J. Synthesis 2013, 45, 979.
(7) (a) Zhao, J.; Li, P.; Xia, C.; Li, F. Chem. Commun. 2014, 50, 4751.
(b) Guo, S.; Yu, J.-T.; Dai, Q.; Yang, H.; Cheng, J. Chem. Commun.
2014, 50, 6240. (c) Wu, X.-F.; Gong, J.-L.; Qi, X. Org. Biomol.
Chem. 2014, 12, 5807. (d) Jia, Z.; Nagano, T.; Li, X.; Chan, A. S. C.
7.60 (m, 1 H), 7.58–7.53 (m, 2 H), 3.73 (t, J = 4.8 Hz, 4 H), 3.00 (t,
J = 4.7 Hz, 4 H). 13C NMR (125 MHz, CDCl3): δ = 135.1, 133.0,
129.1, 127.8, 66.0, 45.9. ESI-MS: m/z (%) = 228 (100) [M + H]+.
N-(4-Chlorobenzyl)-4-methylbenzenesulfonamide (3k)
White solid; mp 92–93 °C (lit.15 88 °C). IR (KBr): 3234, 1641,
© Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–F

F
S. Wu et al.
Letter
Synlett
1492, 1319, 1157, 1091, 816, 549 cm–1
.
1H NMR (500 MHz,
(12) Cano, R.; Ramón, D. J.; Yus, M. J. Org. Chem. 2011, 76, 5547.
CDCl3): δ = 7.71 (d, J = 8.3 Hz, 2 H), 7.28 (d, J = 8.0 Hz, 3 H), 7.21
(d, J = 8.5 Hz, 2 H), 7.12 (d, J = 8.5 Hz, 2 H), 5.27 (t, J = 6.3 Hz, 1
H), 4.07 (d, J = 6.4 Hz, 2 H), 2.44 (s, 3 H). 13C NMR (125 MHz,
CDCl3): δ = 143.6, 136.8, 135.0, 133.6, 129.8, 129.2, 128.7, 127.1,
46.5, 21.5. ESI-MS: m/z (%) = 313 (73) [M + NH4]+.
(13) Molander, G. A.; Fleury-Brégeot, N.; Hiebel, M.-A. Org. Lett.
2011, 13, 1694.
(14) Modarresi-Alam, A. R.; Amirazizi, H. A.; Bagheri, H.; Bijanzadeh,
H.-R.; Kleinpeter, E. J. Org. Chem. 2009, 74, 4740.
(15) Cui, X.; Shi, F.; Tse, M. K.; Gördes, D.; Thurow, K.; Beller, M.;
Deng, Y. Adv. Synth. Catal. 2009, 351, 2949.
(11) (a) Otto, R.; Ostrop, H. Ann. 1867, 141, 365. (b) Otto, R.; von
Gruber, O. Ann. 1867, 142, 92.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–F