Fast, efficient, and convenient method for the preparation of arylazo aryl sulfones using stable aryldiazonium silica sulfates under mild conditions

Article abstract of DOI:10.1055/s-0029-1219811

An efficient, fast, and straightforward procedure for the synthesis of arylazo aryl sulfones is described by using aryl diazonium silica sulfates and sodium arenesulfinates. The reaction was carried out at room temperature under mild conditions. The use o

Full text of DOI:10.1055/s-0029-1219811

LETTER
1201
Fast, Efficient, and Convenient Method for the Preparation of Arylazo Aryl
Sulfones Using Stable Aryldiazonium Silica Sulfates under Mild Conditions
Preparaton of
Arylm
azoAryl Sulfones in Zarei,*a Abdol R. Hajipour,b,c Leila Khazdooz,d Hamidreza Aghaeie
a
Department of Science, Islamic Azad University, Fasa Branch, PO Box 364, Fasa 7461713591, Fars, Iran
Fax +98(311)2289113; E-mail: aj_zarei@yahoo.com
b
c
d
e
Pharmaceutical Research Laboratory, College of Chemistry, Isfahan University of Technology, Isfahan 84156, Iran
Department of Pharmacology, University of Wisconsin, Medical School, 1300 University Avenue, Madison WI 53706-1532, USA
Department of Science, Islamic Azad University, Khorasgan Branch, Isfahan 81595-158, Iran
Department of Chemistry, Islamic Azad University, Shahreza Branch, Shahreza 311-86145, Isfahan, Iran
Received 3 November 2009
um salts with high stability and versatility that can be eas-
ily made and stored under solid-state conditions without
risk of explosion are highly desirable. Aryldiazonium
tetrafluoroborates,1a,9 aryldiazonium hexafluorophos-
Abstract: An efficient, fast, and straightforward procedure for the
synthesis of arylazo aryl sulfones is described by using aryl diazo-
nium silica sulfates and sodium arenesulfinates. The reaction was
carried out at room temperature under mild conditions. The use of
inexpensive materials, simple and clean workup, short reaction phates,1a–d arenediazonium o-benezenedisulfonimides10
and arenediazonium arylsufonates11 are a representative
times, and good yields are the advantages of this method.
diazonium salts possessing these properties.
Key words: aryl diazonium silica sulfates, sodium arenesulfinates,
arylazo aryl sulfones
O
O
S
O
grinding
+
Ar
N
N
R
R
S
O Na
ArN2 OSO3-SiO2
r.t., 10–15 min
Aromatic diazonium salts have been prepared and studied
for years. These salts are important building blocks in
classical and modern organic synthesis,1and interest in
these versatile and reactive species remains high. Arylazo
aryl sulfones (arenediazosulfones) have been studied
from their thermal2 and photochemical3 behavior as well
as their stability toward acids4 and bases5 and various re-
agents.6 Arylazo aryl sulfones are prepared by the reaction
of arenediazonium salts with sulfinic acid salts.6a,7 Al-
though some of these methods are convenient protocols
with good yields, some of them suffer from disadvantages
such as long reaction times, low yields, and requirement
of toxic solvents. In continuation of our studies on the sta-
bilization of diazonium salts on silica sulfuric acid and
their applications in organic synthesis,8 we report herein
an efficient, fast, and convenient procedure for the synthe-
sis of arylazo aryl sulfones employing aryl diazonium sil-
ica sulfates in the presence of sodium arenesulfinates at
room temperature under solvent-free conditions
(Scheme 1).
R = Ph, 4-Tol
Scheme 1
Recently, we have shown that silica sulfuric acid12 serves
as a mild solid acid for the fast preparation of aryldiazoni-
um salts supported on the surface of this solid reagent
(aryldiazonium silica sulfates).8 We found that these new
aryldiazonium salts, ArN2+–OSO3-SiO2, were sufficiently
stable and could be kept at room temperature under anhy-
drous conditions.8 For example, 4-nitrophenyl diazonium
silica sulfate, which had been stored in a desiccator at
room temperature for three days, reacted with sodium
benzenesulfinate under solvent-free conditions and pro-
vided almost the same yield of 4-nitrophenylazo phenyl
sulfone as when prepared from fresh 4-nitrophenyl diazo-
nium silica sulfate (Table 1, entry 12). To illustrate the
scope of the present method, a range of aromatic amines
was rapidly converted to the corresponding arylazo aryl
sulfones in good to high yields under mild conditions
(Table 1). In contrast to related methodology, aromatic
amines with electron-withdrawing groups or electron-do-
nating groups also reacted.
Although diazonium salts have wide applications in the
synthesis of various compounds, these salts have a serious
drawback in their intrinsic instability and explosive poten-
tial. Therefore, these compounds are usually synthesized
at around 10 °C, and to avoid their decomposition, they
are handled below 0 °C. Moreover, due to this instability,
subsequent reactions with diazonium salts must be carried
out in the same conditions which were produced. These
problems restrict chemists applying potentially important
transformations of these salts.1a Therefore, new diazoni-
The steric effects of ortho substituents had relatively little
influence on the reaction time (Table 1, entries 5, 7, 14,
16). The corresponding phenol derivatives were formed in
trace yields as byproducts. The crude products were ex-
tracted with ethyl acetate and, if necessary, were purified
by short column chromatography. In contrast to conven-
tional methods, the reaction rate is rapid because, by sup-
porting the aryldiazonium salt on silica sulfuric acid, the
surface area of the reaction increases.8,13 Finally, after
completion of the reaction and isolation of the product, the
SYNLETT 2010, No. 8, pp 1201–1204
x
x.
x
x.
2
0
1
0
Advanced online publication: 09.04.2010
DOI: 10.1055/s-0029-1219811; Art ID: D31209ST
© Georg Thieme Verlag Stuttgart · New York

1202
A. Zarei et al.
LETTER
solid support could be recycled.8 In addition, the present um salts on the surface of silica sulfuric acid as a bulky
procedure for the preparation of arylazo aryl sulfones is support, the stability of these salts increases.8,14
safe and nonexplosive because by supporting aryldiazoni-
Table 1 Preparation of (E)-Arylazo Aryl Sulfones Using Aryl Diazonium Silica Sulfates at Room Temperaturea
Entry
1
Sodium arenesulfinates Aromatic amines
Products
Time (min) Yield (%)
O
S
PhNH2
10
10
10
10
77
75
72
81
SO2Na
N
N
O
O
S
2
3
4
4-MeC6H4NH2
4-MeOC6H4NH2
4-BrC6H4NH2
Me
N N
O
O
MeO
Br
N
N
S
O
O
S
N
N
N
N
O
O
S
N
N
5
6
7
2-BrC6H4NH2
4-ClC6H4NH2
2-ClC6H4NH2
15
10
15
79
83
89
O
Br
O
S
Cl
N
O
O
S
N
N
O
Cl
O
S
N
8
3-ClC6H4NH2
10
80
O
Cl
O
9
10
11
12
4-NCC6H4NH2
10
10
15
10
82
85
76
82
NC
N
N
S
O
O
O
S
4-MeCOC6H4NH2
4-H2NC6H4COOH
4-O2NC6H4NH2
Me
C
N
N
N
N
O
O
S
HOOC
O2N
O
O
N
N
S
O
O
S
N
N
13
14
3-O2NC6H4NH2
2-O2NC6H4NH2
10
15
76
78
O
O2N
O
N
N
S
O
NO2
Synlett 2010, No. 8, 1201–1204 © Thieme Stuttgart · New York

LETTER
Preparaton of Arylazo Aryl Sulfones
1203
Table 1 Preparation of (E)-Arylazo Aryl Sulfones Using Aryl Diazonium Silica Sulfates at Room Temperaturea (continued)
Entry
15
Sodium arenesulfinates Aromatic amines
Products
Time (min) Yield (%)
O
S
NH2
N
N
10
15
70
81
O
N
N
O
S
O
C
NH2
O
C
N N
16
17
O
O
O
C
C
N
10
80
O
S
Me
N N
Me
NH2
O
O
18
19
20
21
22
PhNH2
10
10
10
10
10
76
74
72
81
80
Me
SO2Na
N
S
Me
O
O
4-MeC6H4NH2
4-MeOC6H4NH2
4-ClC6H4NH2
Me
MeO
Cl
N
N
S
Me
O
O
N
N
S
Me
O
O
N
N
S
Me
O
O
S
4-O2NC6H4NH2
O2N
N
N
Me
O
a The yields refer to isolated pure products which were characterized from their spectroscopic data and by comparison with authentic samples.6,7
7.91 (2 H, d, J = 8.4 Hz), 7.82 (2 H, d, J = 8.4 Hz), 7.77 (1 H, t,
J = 7.2 Hz), 7.64 (2 H, t, J = 7.6 Hz). 13C NMR (100 MHz, CDCl3):
d = 150.85, 135.22, 133.55, 132.31, 130.54, 129.42, 124.74,
117.65, 117.45. ESI-HRMS: m/z calcd for C13H9N3O2S [M + H]+:
272.0415; found: 272.1811. Anal. Calcd for C13H9N3O2S: C, 57.55;
H, 3.34; N, 15.49; S, 11.82. Found: C, 57.36; H, 3.51; N, 15.61; S,
11.67.
In summary, we have developed an efficient, rapid, exper-
imentally simple, and environmentally benign method for
the preparation of arylazo aryl sulfones using aryldiazoni-
um silica sulfates. These reactions proceed at room tem-
perature under mild conditions in good to high yields.
Further investigations on new applications of these salts
are ongoing in our laboratories.
Table 1, Entry 10
Light brown solid; mp 113–115 °C. IR (KBr): 3093, 1689, 1598,
1579, 1464, 1445, 1404, 1352, 1310, 1256, 1171, 1147, 1082, 1004,
959, 883, 844, 755, 729 cm–1. 1H NMR (400 MHz, CDCl3): d = 8.08
(2 H, d, J = 8.4 Hz), 8.01 (2 H, d, J = 7.2 Hz), 7.89 (2 H, d, J = 8.4
Hz), 7.75 (1 H, t, J = 7.6 Hz), 7.64 (2 H, t, J = 7.6 Hz), 2.66 (3 H,
s). 13C NMR (100 MHz, CDCl3): d = 196.85, 151.28, 141.19,
135.00, 132.65, 130.50, 129.47, 129.33, 124.52, 26.93. ESI-HRMS:
m/z calcd for C14H12N2O3S [M + H]+: 289.0569; found, 289.1922.
Anal. Calcd for C14H12N2O3S: C, 58.32; H, 4.20; N, 9.72; S, 11.12.
Found: C, 58.12; H, 4.34; N, 9.63; S, 11.25.
Typical Procedure for the Preparation of 4-Nitrophenyazo Phe-
nyl Sulfone
Sodium benzenesulfinate (1.8 mmol, 0.3 g) was added to freshly
prepared 4-nitrophenyl diazonium silica sulfate8 (1 mmol), and the
reaction mixture was ground with a pestle in a mortar for 10 min at
r.t. The mixture was diluted with EtOAc (12 mL) and, after vigorous
stirring, was filtered. The residue was extracted with EtOAc (3 × 12
mL), and the combined organic layer was washed with 5% NaOH
solution and then dried over anhyd Na2SO4. The solvent was evap-
orated to afford 4-nitrophenyazo phenyl sulfone in 82% yield
(0.0.238 g).
Table 1, Entry 11
Orange solid; mp 132–134 °C. IR (KBr): 3101-2550, 1691, 1603,
1580, 1470, 1430, 1351, 1321, 1294, 1166, 1085, 1012, 955, 871,
808, 777, 720 cm–1. 1H NMR (400 MHz, CDCl3/DMSO-d6):
d = 7.99 (2 H, d, J = 8.8 Hz), 7.79 (2 H, d, J = 7.8 Hz), 7.66 (2 H, d,
The Spectral Data of New Compounds
Table 1, Entry 9
Brown solid; mp 104–106 °C. IR (KBr): 3096, 2226, 1581, 1496,
J = 8.8 Hz), 7.60 (1 H, t, J = 7.6 Hz), 7.47 (2 H, t, J = 7.6 Hz). 13
C
1447, 1404, 1353, 1305, 1183, 1164, 1084, 882, 853, 785, 753, 730
NMR (100 MHz, CDCl3/DMSO-d6): d = 166.82, 151.03, 136.37,
134.93, 132.45, 130.86, 130.27, 129.23, 123.95. Anal. Calcd for
1
cm–1. H NMR (400 MHz, CDCl3): d = 8.00 (2 H, d, J = 8.0 Hz),
Synlett 2010, No. 8, 1201–1204 © Thieme Stuttgart · New York

1204
A. Zarei et al.
LETTER
Chem. 2007, 72, 7477. (f) Yu, S. S. C.; Downnard, A. J.
Langmuir 2007, 23, 4662. (g) Olah, G. A.; Laali, K. K.;
Wang, Q.; Prakash, G. K. S. Onium Ions; Wiley: New York,
1998.
C13H10N2O4S: C, 53.79; H, 3.47; N, 9.65; S, 11.05. Found: C, 53.68;
H, 3.56; N, 9.54; S, 10.94.
Table 1, Entry 13
Yellow solid; mp 119–121 °C. IR (KBr): 3100, 1608, 1582, 1527,
1349, 1312, 1171, 1075, 997, 906, 843, 814, 752, 740, 727 cm–1. 1H
NMR (400 MHz, CDCl3): d = 8.63 (1 H, s), 8.46 (1 H, d, J = 8.4
Hz), 8.18 (1 H, d, J = 7.6 Hz), 8.01 (2 H, d, J = 7.6 Hz), 7.81–7.73
(2 H, m), 7.66 (2 H, t, J = 7.6 Hz). 13C NMR (100 MHz, CDCl3):
d = 149.39 148.96, 135.27, 132.31, 130.71, 130.56, 129.46, 128.45,
119.35. ESI-HRMS: m/z calcd for C12H9N3O4S [M + H]+:
292.0314; found, 292.2346. Anal. Calcd for C12H9N3O4S: C, 49.48;
H, 3.11; N, 14.43; S, 11.01. Found: C, 49.29; H, 3.32; N, 14.37; S,
11.18.
(2) (a) Rosenthal, A. J.; Overberger, C. G. J. Am. Chem. Soc.
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Table 1, Entry 15
Yellow solid; mp 103–105 °C. IR (KBr): 3095, 3071, 1575, 1488,
1466, 1451, 1420, 1348, 1195, 1167, 1083, 1016, 970, 879, 818,
775, 755, 701 cm–1. 1H NMR (400 MHz, CDCl3): d = 9.05 (1 H, s),
8.82 (1 H, d, J = 4.0 Hz), 8.07 (1 H, d, J = 8.0 Hz), 8.00 (2 H, d,
J = 7.6 Hz), 7.77 (1 H, t, J = 7.6 Hz), 7.64 (2 H, t, J = 7.6 Hz), 7.48
(1 H, m). 13C NMR (100 MHz, CDCl3): d = 155.33, 149.00, 144.66,
135.10, 132.46, 130.47, 129.37, 127.56, 124.39. ESI-HRMS: m/z
calcd for C11H9N3O2S [M + H]+: 248.0415; found: 248.02451. Anal.
Calcd for C11H9N3O2S: C, 53.43; H, 3.67; N, 16.99; S, 12.97.
Found: C, 53.49; H, 3.79; N, 16.84; S, 12.88.
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Table 1, Entry 16
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Tetrahedron Lett. 2009, 50, 4443.
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1572. (b) Cygler, M.; Przybylska, M.; Elofson, R. M. Can.
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Laali, K. K. J. Org. Chem. 2008, 73, 316.
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3448.
(11) (a) Krasnokutskaya, E. A.; Semenischeva, N. I.; Filimonov,
V. D.; Knochel, P. Synthesis 2007, 81. (b) Filimonov, V.
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Mohammadpoor-Baltork, I. Green Chem. 2002, 4, 562.
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M. A.; Zarei, A.; Khazdooz, L.; Noei, J. Bull. Korean Chem.
Soc. 2004, 25, 1414. (e) Hajipour, A. R.; Zarei, A.;
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Yellow solid; mp 105–107 °C. IR (KBr): 3062, 1666, 1593, 1579,
1491, 1449, 1348, 1317, 1287, 1246, 1182, 1160, 1082, 998, 931,
885, 806, 767, 720 cm–1. 1H NMR (400 MHz, CDCl3): d = 7.86 (1
H, d, J = 8.4 Hz), 7.71 (1 H, t, J = 7.6 Hz), 7.64 (1 H, t, J = 7.2 Hz),
7.57 (1 H, t, J = 7.2 Hz), 7.53–7.48 (4 H, m), 7.44–7.36 (4 H, m),
7.27 (2 H, m). 13C NMR (100 MHz, CDCl3): d = 194.75, 146.17,
141.37, 136.94, 134.82, 134.40, 133.57, 131.52, 130.83, 130.19,
129.91, 128.79, 128.70, 128.46, 117.13. ESI-HRMS: m/z calcd for
C19H14N2O3S [M + H]+: 351.0725; found: 351.01651. Anal. Calcd
for C19H14N2O3S: C, 65.13; H, 4.03; N, 7.99; S, 9.15. Found: C,
65.02; H, 4.21; N, 7.86; S, 9.01.
Table 1, Entry 17
Orange solid; mp 115–117 °C. IR (KBr): 3065, 1648, 1604, 1582,
1466, 1448, 1406, 1352, 1311, 1285, 1167, 1084, 932, 883, 861,
1
833, 757 cm–1. H NMR (400 MHz, CDCl3): d = 8.02 (2 H, d,
J = 8.4 Hz), 7.92 (2 H, d, J = 8.4 Hz), 7.88 (2 H, d, J = 8.8 Hz), 7.76
(1 H, t, J = 7.6 Hz), 7.70 (2 H, d, J = 8.0 Hz), 7.64 (2 H, t, J = 7.6
Hz), 7.30 (2 H, d, J = 8.0 Hz), 2.46 (3 H, s). 13C NMR (100 MHz,
CDCl3): d = 195.00, 150.66, 144.27, 143.07, 134.96, 133.94,
132.79, 131.10, 130.81, 130.49, 130.30, 129.28, 124.34, 21.73.
ESI-HRMS: m/z calcd for C20H16N2O3S [M + H]+: 365.0882; found:
365.1694. Anal. Calcd for C20H16N2O3S: C, 65.92; H, 4.43; N, 7.69;
S, 8.80. Found: C, 65.78; H, 4.39; N, 7.83; S, 8.93.
Acknowledgment
We gratefully acknowledge the funding support received for this
project from the Islamic Azad University of Fasa and the Isfahan
University of Technology (IUT).
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Inorganic Reagents; VCH: Weinheim, 1994.
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