Solvent-free one pot synthesis of 2-aryl/heteroarylbenzothiazoles using hypervalent iodine (III) reagents

Article abstract of DOI:10.1002/jhet.962

In this article, an efficient, environmentally benign, one-pot and simple synthesis of 2-aryl/heteroarylbenzothiazoles by the reaction of 2-aminothiophenol and aryl/heteroaryl aldehydes mediated by hypervalent iodine (III) reagents under solvent-free cond

Full text of DOI:10.1002/jhet.962

September 2012
Solvent‐Free One Pot Synthesis of 2‐aryl/
1243
Heteroarylbenzothiazoles Using Hypervalent Iodine (III) Reagents
a
b
c
d
e
a
*
Parvin Kumar, Meenakshi, Sunil Kumar, Ashwani Kumar, Khalid Hussain, and Suresh Kumar
aDepartment of Chemistry, Kurukshetra University, Kurukshetra, Haryana‐136119, India
bDepartment of Chemistry, Guru Jambheshwar University of Science & Technology, Hissar, Haryana‐125001, India
cChemistry Department, Government P. G. College, Hissar, Haryana‐125001, India
dDrug Discovery and Research Laboratory, Department of Pharmaceutical Sciences, Guru Jambheshwar University of
Science & Technology, Hissar, Haryana‐125001, India
eChemistry Department, Guru Nanak Khalsa College, Yamuna Nagar, Haryana‐135001, India
*
E-mail: drpkawasthignkc@rediffmail.com
Received February 27, 2011
DOI 10.1002/jhet.962
Published online 26 October 2012 in Wiley Online Library (wileyonlinelibrary.com).
In this article, an efficient, environmentally benign, one‐pot and simple synthesis of 2‐aryl/heteroarylben-
zothiazoles by the reaction of 2‐aminothiophenol and aryl/heteroaryl aldehydes mediated by hypervalent
iodine (III) reagents under solvent‐free condition at room temperature is demonstrated. All the reactions were
carried out by grinding the reactants (2‐aminothiophenol and aryl/heteroaryl aldehydes) with hypervalent
iodine (III) reagents in a mortar with pestle. Phenyliodine bistrifluoroacetate act as an efficient oxidizing
reagent in comparison to iodobenzene diacetate in term of reaction time but yields are comparative. The
advantages of this protocol are the one‐step procedure, mild reaction conditions, high yields of the products,
and no side reactions.
J. Heterocyclic Chem., 49, 1243 (2012).
INTRODUCTION
Of these strategies (Scheme 1), we selected the oxidative
condensation of 2‐aminothiophenol and 2‐aryl/heteroaryl
aldehydes mediated by hypervalent iodine (III) reagents [iodo-
benzene diacetate (IBD) or phenyliodine bistrifluoroacetate
(PIFA)]. The reactions were carried out under solvent‐free
conditions, by just grinding the reaction partners using mortar
and pestle, a technique known as “Grindstone Chemistry.”
The principle of green chemistry obliges us to check the use
of organic solvents. For reasons of economy and pollution,
solvent‐free methods are of great interest in order to modern-
ize classical procedures making them more clean, safe, and
easy to perform. Hypervalent iodine (III) reagents have gained
much importance as an oxidizing reagent due to their environ-
mentally benign properties and replacing the use of toxic tran-
sition metals involved in such processes [39, 40]. The poor
solubility of hypervalent iodine (III) reagents in most common
organic solvents led to the development of solvent‐free reac-
tions [41, 42], which is demonstrated here.
Benzothiazoles and their derivatives have gained very
much importance during the last decades. 2‐Arylbenzothia-
zoles, an important class of heterocyclic compounds,
possess potent medicinal, and industrial applications [1–
10]. This heterocyclic scaffold is found in natural products
as well as in synthetic derivatives. Firefly luciferin [(S)‐
2‐(6′‐hydroxy‐2′‐benzothiazolyl)thiazoline‐4‐carboxylic acid]
is a benzothiazolyl derivative [11]: the bioluminescence
is produced by photo‐oxygenation at the asymmetric
center (Fig. 1). 2‐Amino‐6‐(trifluoromethoxy)benzothiazole
(Riluzole) is applied to treat a nerve disease called amyotrophic
lateral sclerosis (Lou Gehrig’s disease) (Fig. 1) [12].
2‐Arylbenzothiazoles are most commonly synthesized by
one of the major routes as outlined in Scheme 1 [13–38].
Despite these intensive efforts, most of the existing methods
suffer from certain shortcomings such as poor yields, long
reaction times, side products, high temperature, use of strong
oxidants, and toxic solvents. Therefore, development and
introduction of an expedient, milder and efficient, preferably
an environmentally benign protocol to conquer these nega-
tive aspects is an exigent assignment for organic researcher.
Keeping above facts in mind, we planned to develop an
expedient, milder, and efficient method for the synthesis of
2‐aryl/heteroarylbenzothiazole.
RESULTS AND DISCUSSION
In continuation on the synthesis of biologically active
heterocycles and our ongoing attention to the development
of new methodologies [42, 43], herein we describe the sol-
vent‐free oxidative condensation of 2‐aminothiophenol
© 2012 HeteroCorporation

1244
P. Kumar, Meenakshi, S. Kumar, A. Kumar, K. Hussain, and S. Kumar
Vol 49
Figure 1. Some important compounds having benzothiazole moiety.
and 2‐aryl/heteroaryl aldehydes using hypervalent iodine
(III) reagents. The high oxidizing power of IBD and PIFA
led us to hypothesize that these can act as efficient oxidiz-
ing reagents for this protocol (Scheme 2). To the best of
our knowledge, the generality and applicability of hyperva-
lent iodine (III) reagents under solvent‐free conditions for
the synthesis of benzothiazoles is not known.
In a typical reaction, an equimolar amount of 2‐aminothio-
phenol (1.0 mmol) and benzaldehyde (1.0 mmol) were
mixed in a mortar by pestle for 1–2 min. The reaction
mixture became cloudy after 1 min and gradually solidified.
Then IBD (1.2 mmol) or PIFA (1.2 mmol) was added and the
reaction mixture was ground at room temperature for the
time as indicated in Table 1. Suddenly, exothermic reaction
occurred and reaction mixture became wet with generation
of acetic acid or trifluoroacetic acid. After usual workup,
2‐phenylbenzothiazole 3 was obtained in excellent yield
[90% (IBD), 92% (PIFA)].
To check the generality of this organic transformation,
various substituted aryl/heteroaryl aldehydes and 2‐ami-
nothiophenol were condensed in the presence of hypervalent
iodine (III) reagents to afford 2‐aryl/heteroarylbenzothiazoles
in high yield (80–95%). The synthesis of benzothiazoles was
supported by elemental analysis, IR and 1H‐NMR (vide
experimental). Reactions proceed smoothly and the effect of
an electron donating or an electron‐withdrawing group on
the aromatic ring of the aldehydes was not observed. The time
required for the PIFA mediated benzothiazoles synthesis is
less then the IBD but yields are comparative (Table 1).
The proposed mechanism for the formation of benzothia-
zoles is sketched in Scheme 3. 2‐Aminothiophenol reacts
with aldehydes to give 2‐aryl/heteroaryl benzothiazolines
or Schiff’s bases. The nitrogen of benzothiazolines attacks
on the nucleophilic iodine of the hypervalent iodine (III)
reagents displacing one of the acetate or trifluoroacetate
groups, giving N‐iodine (III) adduct, followed by elimination
of iodobenzene and acetic acid or trifluoroacetic acid.
The current method was found to be extremely convenient
for selective synthesis of 2‐aryl/heteroarylbenzothiazoles.
No side reaction of sulfur radical was found to take place un-
der these conditions. Therefore, the present protocol for the
synthesis of 2‐aryl/heteroarylbenzothiazoles using hyperva-
lent iodine (III) reagents would be superior to the previously
reported methods because of (i) less time consumption, (ii)
solvent‐free synthesis, (iii) high yields, (iv) no side reaction
such as oxidation of sulfur, and (v) very simple workup.
In summary, we have described a general and practical route
for the synthesis of 2‐aryl/heteroarylbenzothiazoles using hyper-
valent iodine (III) reagents under solvent‐free conditions. The
methodology is applicable to a wide variety of structurally
diverse substrates and delivers the target products in good yields,
excellent homogeneity, and often in analytically pure form.
Scheme 1. Strategies for the synthesis of benzothiazoles.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

September 2012
Solvent‐Free One Pot Synthesis of 2‐Aryl/Heteroarylbenzothiazoles Using Hypervalent
1245
Iodine (III) Reagents
Scheme 2. Synthesis of 2‐aryl/heteroarybenzothiazoles using hypervalent
iodine (III) reagents under solvent‐free condition.
EXPERIMENTAL
All chemicals used in this study were purchased from local
venders and used without further purification. Melting points were
determined on buchi oil heating melting apparatus and are uncor-
1
rected. H‐NMR spectra were recorded in CDCl3 on Brucker‐400
MHz spectrometer using TMS as internal standard (chemical
Table 1
Solvent‐free synthesis of 2‐aryl/heteroarylbenothiazoles mediated by hypervalent iodine (III) reagents.
Timea (min)
IBD PIFA
Yieldb (%)
S. No.
Entries
R
Mpc (°C)
Lit. Mp (°C)
IBD
PIFA
92
1
3
4
5
6
2
3
90
89
113–114
231–232
112–113 [38]
230–231 [38]
2
94
3
4
5
6
6
6
3
3
90
85
90
87
183–184
138–139
183–185 [26]
138–140 [18(a)]
5
7
6
3
91
92
120–121
119–120 [38]
6
7
8
9
5
5
3
3
85
85
85
85
101–102
142–143
101–102 [18(a)]
142–144 [26]
8
10
7
3
86
85
175–176
173–174 [38]
9
11
12
7
8
3
4
86
86
87
90
86–87
85–86 [38]
10
160–161
159–160 [27(g)]
11
12
13
13
14
15
8
8
8
4
4
4
89
92
89
91
92
95
118–119
130–132
100–101
117–118 [38]
131–132 [38]
101–102 [38]
14
15
16
16
17
18
10
10
10
4
4
4
80
81
80
85
86
85
103–104
100–101
123–124
102–103 [38]
99–100 [38]
124–125 [27(g)]
17
19
9
5
80
89
125–126
127 [27(g)]
(Continued)
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

1246
P. Kumar, Meenakshi, S. Kumar, A. Kumar, K. Hussain, and S. Kumar
Vol 49
Table 1
(Continued)
Timea (min)
IBD PIFA
Yieldb (%)
S. No.
Entries
R
Mpc (°C)
Lit. Mp (°C)
IBD
PIFA
85
18
19
20
21
9
8
5
5
80
84
133–134
98–99
132–133 [27(g)]
97–98 [27(o)]
91
92
92
20
21
22
23
7
8
4
3
85
90
119–120
148–149
117–118 [27(o)]
147–148 [27(o)]
22
24
8
4
88
94
85–86
84–85 [27(p)]
23
24
25
25
26
27
9
5
5
5
88
90
82
95
92
85
99–100
166–168
137–138
97–99 [27(q)]
167 [27(q)]
10
10
129–130 [38]
26
27
28
29
28
29
30
31
10
10
10
10
5
5
5
5
83
83
80
81
85
83
85
82
179–180
210–212
202–203
170–171
159–160 [38]
200–202 [27(j)]
173–175 [27(j)]
167–169 [27(j)]
aTime for grinding after adding of IBD or PIFA.
bYields are isolated.
cMelting points are uncorrected and compared with literature reports.
shift in δ, ppm). IR spectra were taken on a PerkinElmer 1600, FTIR
hexane to remove iodobenzene, then added saturated solution of
aq. NaHCO3 to quench the reaction and filtered the product. The
solid thus obtained was recrystallized with methanol to afford 2‐
aryl/heteroarylbenzothiazoles.
The spectral and analytical data of 2‐aryl/heteroaryl benzothia-
zoles is as follows:
2‐(4‐Nitrophenyl)benzothiazole (4). IR (KBr, cm−1): 3036,
1603, 1585, 1542, 1504, 1465, 1341, 873, 761. 1H NMR
(400 MHz, CDCl3) δ: 7.32–7.38 (m, 1H), 7.45–7.51 (m, 1H),
7.75–7.85 (m, 3H), 8.01–8.03 (d, J = 8.13 Hz, 1H), 8.25 (d, J =
7.8 Hz, 2H). Anal. Calcd. for. C13H8N2O2S: C, 60.93; H, 3.15;
N, 10.93. Found: C, 61.06; H, 3.21; N, 11.01.
spectrophotometer using KBr pellets and peaks are reported in cm−1.
General procedure for the synthesis of 2‐aryl/heteroaryl-
benzothiazoles. A mixture of 2‐aminothiophenol (1.0 mmol) and
aldehyde (1.0 mmol) was blended thoroughly in pestle with
mortar for 2 min. The reaction mixture became cloudy after 1 min
and gradually solidified. Then we added hypervalent iodine (III)
reagent (1.2 mmol) and ground the reaction mixture for the time
indicated in Table 1. Suddenly exothermic reaction occurred and
reaction mixture became wet with generation of acetic acid or
trifluoroacetic acid. Progress of reaction was monitored on TLC.
After completion of reaction, reaction mixture was triturated with
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

September 2012
Solvent‐Free One Pot Synthesis of 2‐Aryl/Heteroarylbenzothiazoles Using Hypervalent
1247
Iodine (III) Reagents
Scheme 3. Mechanistic pathway for the synthesis of benzothiazoles.
2‐(4‐Methoxyphenyl)benzothiazole (7). IR (KBr, cm−1): 3053,
2925, 1601, 1577, 1466, 1210, 1023, 835, 737. H‐NMR (400
2‐(2‐Chlorophenyl)benzothiazole (24). IR (KBr, cm−1): 3055,
1
1605, 1589, 1425, 1242, 1022, 752. 1H‐NMR (400 MHz, CDCl3)
δ: 7.32–7.36 (m, 2H), 7.41–7.56 (m, 3H), 7.69–7.71 (m, 1H),
7.80–7.83 (m, 1H), 8.01–8.03 (d, J = 8.8 Hz, 1H). Anal. Calcd.
for: C13H8ClNS: C, 63.54; H, 3.28; N, 5.70. Found: C, 63.48;
H, 3.33; N, 5.58.
MHz, CDCl3) δ 3.90 (3H, s), 6.95–7.00 (2H, m), 7.32–7.36
(m, 1H), 7.45–7.51 (m, 1H), 7.65–7.69 (m, 2H), 7.76–7.78 (m,
1H), 8.00–8.02 (d, J = 8.1 Hz, 1H). Anal. Calcd. for
C14H11NOS: C, 69.68; H, 4.59; N, 5.80. Found: C, 69.86; H,
4.62; N, 5.68.
2‐(1,3‐Diphenyl‐1H‐pyrazol‐4‐yl)benzothiazole (27). IR
2‐(3‐Methoxyphenyl)benzothiazole (8). IR (KBr, cm−1): 3035,
(KBr, cm−1): 3035, 1612, 1558, 1525, 1496, 1448, 1255,
1
1
2923, 1612, 1575, 1462, 1415, 1266, 1019, 786, 755. H‐NMR
1012, 967, 938, 751. H‐ NMR (400 MHz, CDCl3): δ 7.29–
(400 MHz, CDCl3) δ: 3.96 (s, 3H), 7.00–7.10 (m, 1H), 7.30–7.37
(m, 3H), 7.46–7.51(m, 2H), 7.65–7.78 (m, 2H), 7.99–8.01 (d, J =
8.0 Hz, 1H). Anal. Calcd. for: C14H11NOS: C, 69.68; H, 4.59; N,
5.80. Found: C, 69.73; H, 4.49; N, 5.72.
7.36 (m, 2H), 7.45–7.51 (m, 6H), 7.76–7.78 (m, 3H), 7.83
(d, J = 8.0 Hz, 2H), 8.00(d, J = 8.1 Hz, 1H), 8.63 (s, 1H).
Anal. Calcd. for C22H15N3S: C, 74.76; H, 4.28; N, 11.82.
Found: C, 74.82; H, 4.25; N, 11.75.
2‐(4‐Trifluoromethyl‐phenyl)benzothiazole (12). IR (KBr,
cm−1): 3055, 1608, 1578, 1504, 1465, 1222, 845, 760. 1H‐NMR
(400 MHz, CDCl3): δ 7.33–7.35 (m, 1H), 7.41–7.51 (m, 1H),
7.65 (d, J = 7.7 Hz, 2H), 7.76–7.78 (m, 1H), 8.01–8.02 (d, J =
8.0 Hz, 1H), 8.12 (d, J = 7.7 Hz, 2H). Anal. Calcd. for
C14H8F3NS: C, 60.21; H, 2.89; N, 5.02. Found: C, 60.09; H,
2.77; N, 4.96.
2‐(1‐Phenyl‐3‐p‐tolyl‐1H‐pyrazol‐4‐yl)benzothiazole (28). IR
(KBr, cm−1): 3055, 3012, 2915, 1618, 1601, 1581, 1539, 1477,
1310, 1235, 1160, 1012, 971, 733. 1H‐NMR (400 MHz,
CDCl3): δ 2.45 (s, 3H), 7.20–7.35 (m, 4H), 7.41–7.49 (m, 3H),
7.63 (d, J = 7.7 Hz, 2H), 7.76 (d, J = 7.9 Hz, 1H), 7.82 (d, J =
7.7 Hz, 2H), 8.00 (d, J = 8.1 Hz, 1H), 8.64 (s, 1H). Anal.
Calcd. for C23H17N3S: C, 75.18; H, 4.66; N, 11.44. Found: C,
74.99; H, 4.71; N, 11.33.
2‐[3‐(4‐Bromophenyl)‐1‐phenyl‐1H‐pyrazol‐4‐yl)]benzothiazole
(29). IR (KBr, cm−1): 3065, 2933, 1612, 1563, 1505, 1477, 1233,
960, 835, 741. 1H‐NMR (400 MHz, CDCl3): δ 7.34–7.38 (m, 2H),
7.46–7.52 (m, 3H), 7.60 (d, J = 8.4 Hz, 2H), 7.68 (d, J = 8.4 Hz,
2H), 7.80–7.82 (m, 3H), 8.01 (d, J = 8.0 Hz, 1H), 8.60 (s, 1H).
Anal. Calcd. for C22H14BrN3S: C, 61.12; H, 3.26; N, 9.72. Found:
C, 61.06; H, 3.32; N, 9.63.
2‐Thienyl‐1,3‐benzothiazole (17). IR (KBr, cm−1): 3080,
1
3040, 1620. H‐NMR (400 MHz, CDCl3): δ 7.20–7.23 (m, 1H);
7.34–7.38 (m, 1H); 7.45–7.52 (m, 2H); 7.69 (d, J = 4.1 Hz,
1H); 7.80–7.83 (m, 1H), 8.01–8.03 (d, J = 8.0 Hz, 1H). Anal.
Calcd. for C11H7NS2: C, 60.80; H, 3.25; N, 6.45. Found: C,
60.72; H, 3.29; N, 6.49.
2‐Pyridin‐4‐yl‐benzothiazole (20). IR (KBr, cm−1): 3065,
1
3033, 1615, 1585, 1471, 1030, 836, 793. H NMR (400 MHz,
CDCl3) δ 7.34–7.36 (m, 1H), 7.42–7.50 (m, 1H), 7.83–7.88
(3H, m), 8.02–8.04 (d, J = 8.4 Hz, 1H), 8.65 (d, J = 5.8 Hz,
2H). Anal. Calcd. for C12H8N2S: C, 67.90; H, 3.80; N, 13.20.
Found: C, 68.01; H, 3.70; N, 13.05.
2‐[3‐(4‐Chlorophenyl)‐1‐phenyl‐1H‐pyrazol‐4‐yl)]benzothiazole
(30). IR (KBr, cm−1): 3055, 2825, 1622, 1586, 1542, 1499, 1287,
1233, 1088, 1002, 962, 937, 829, 746. 1H‐NMR (400 MHz,
CDCl3): δ 7.34–7.38 (m, 2H), 7.43–7.52 (m, 5H), 7.72–7.75 (m,
2H,), 7.79–7.83 (m, 3H), 8.02 (d, J = 8.1 Hz, 1H), 8.63 (s, 1H).
Anal. Calcd. for C22H14ClN3S: C, 68.12; H, 3.64; N, 10.83.
Found: C, 68.22; H, 3.70; N, 10.74.
2‐Pyridin‐2‐yl‐benzothiazole (22). IR (KBr, cm−1): 3074,
1
3038, 1607, 1588, 1477, 1032, 837, 799. H‐NMR (400 MHz,
CDCl3): δ 7.36–7.42 (m, 2H), 7.50–7.52 (m, 1H), 7.81–7.89
(m, 2H), 7.99–8.03 (m, 1H), 8.27–8.33 (m, 1H), 8.55–58 (m,
1H). Anal. Calcd. for C12H8N2S: C, 67.90; H, 3.80; N, 13.20.
Found: C, 67.85; H, 3.82; N, 13.22.
2‐[3‐(4‐Methoxyphenyl)‐1‐phenyl‐1H‐pyrazol‐4‐yl)]benzothiazole
(31). IR (KBr, cm−1): 3056, 3310, 2938, 1607, 1588, 1522, 1467,
1
1447, 1301, 1242, 1175, 1026, 968, 835, 756. H‐NMR (400 MHz,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

1248
P. Kumar, Meenakshi, S. Kumar, A. Kumar, K. Hussain, and S. Kumar
Vol 49
[18] (a) Chakraborti, A. K.; Rudrawar, S.; Jadhav, K. B.; Kaur, G.;
Chankeshwara, S. V. Green Chem 2007, 9, 1335; (b) Rudrawar, S.;
Kondaskar, A.; Chakraborti, A. K. Synthesis 2005, 15, 2521.
[19] Boger, D. L. J Org Chem 1978, 43, 2296.
[20] Itoh, T.; Mase, T. Org Lett 2007, 9, 3687.
[21] (a) Tale, R. H. Org Lett 2002, 4, 1641; (b) Nair. V.; Augustine,
A. Org Lett 2003, 5, 543.
CDCl3): δ 3.87 (s, 3H), 6.98–7.02 (m, 2H), 7.30–7.36 (m, 2H), 7.44–
7.50 (m, 3H), 7.67–7.69 (m, 2H), 7.76–7.78 (m, 1H), 7.81–7.83 (m,
2H), 8.02 (d, J = 8.0 Hz, 1H), 8.66 (s, 1H). Anal. Calcd. for
C23H17N3OS: C, 72.04; H, 4.47; N, 10.96. Found: C, 72.15; H,
4.41; N, 10.88.
[22] Kawashita, Y.; Ueba, C.; Hayashi, M. Tetrahedron Lett 2006,
47, 4231.
[23] Pratap, U. R.; Mali, J. R.; Jawale, D. V.; Mane, R. A. Tetrahedron
Lett 2009, 50, 1352.
REFERENCES AND NOTES
[24] (a) Ben‐Alloum, A.; Bakkas, S.; Soufiaoui, M. Tetrahedron Lett
1997, 38, 6395; (b) Ranu, B. C.; Jana, R.; Dey, S. Chem Lett 2004, 33, 274;
(c) Li, Y.; Wang, Y. L.; Wang, J. Y. Chem Lett 2006, 35, 460; (d) Moghad-
han, F. M.; Ismaili, H.; Bardajee, G. R. Heteroatom Chem 2006, 17, 136; (e)
Ryabukhin, S. V.; Plaskon, A. S.; Volochnyuk, D. M.; Tolmachev, A. A.
Synthesis 2006, 21, 3715; (f) Praveen, C.; Hemanthkumar, K.; Muralid-
haran, D.; Perumal, P. T. Tetrahedron 2008, 64, 2369; (g) Bahrami, K.;
Khodaei, M. M.; Nali, F. J Org Chem 2008, 73, 6835; (h) Bose, S. D.; Idrees,
M.; Srikanth, B. Synthesis 2007, 6, 819; (i) Melzig, L.; Metzger, A.;
Knochel, P. Chem A Eur J 2011, 17, 2948.
[1] Yoshida, M.; Hayakawa, I.; Hayashi, N.; Agatsuma, T.; Oda,
Y.; Tanzawa, F.; Iwasaki, S.; Koyama, K.; Furukawa, H.; Kurakata, S.;
Sugano, Y. Bioorg Med Chem Lett 2005, 15, 3328.
[2] Choi, S. J.; Park, H. J.; Lee, S. K.; Kim, S. W.; Han, G.; Choo,
H. Y. P. Bioorg Med Chem 2006, 14, 1229.
[3] Ji, S. J.; Shi, H. B. Dyes Pigm 2006, 70, 246.
[4] Razus, A. C.; Birzan, L.; Surugiu, N. M.; Corbu, A. C.;
Chiraleu, F. Dyes Pigm 2007, 74, 26.
[5] (a) Bradshaw, T. D.; Wrigley, S.; Shi, D. F.; Schulz, R. J.;
Paull, K. D.; Stevens, M. F. G. Br J Cancer 1998, 77, 745; (b) Kashiyama,
E.; Hutchinson, I.; Chua, M. S.; Stinson, S. F.; Phillips, L. R.; Kaur, G.;
Sausville, E. A.; Bradshaw, T. D.; Westwell, A. D.; Stevens, M. F. G. J
Med Chem 1999, 42, 4172; (c) Hutchinson, I.; Chua, M. S.; Browne, H.
L.; Trapani, V.; Bradshaw, T. D.; Westwell, A. D.; Stevens, M. F. G. J
Med Chem 2001, 44, 1446; (d) Palmer, P. J.; Trigg, R. B.; Warrington,
J. V. J Med Chem 1971, 14, 248; (e) Hall, I. H.; Peaty, N. J.; Henry, J.
R.; Easmon, J.; Heinisch, G.; Purstinger, G. Arch Pharm (Weinheim)
1999, 332, 115; (f) Beneteau, V.; Besson, T.; Guillard, J.; Leonce, S.;
Pfeiffer, B. Eur J Med Chem 1999, 34, 1053; 5. (g) Hutchinson, I.;
Bradshaw, T. D.; Matthews Stevens, M. F. G.; Westwell, A. D. Bioorg
Med Chem Lett 2003, 13, 471 and the references cited therein.
[6] (a) Caccese, R. G.; Di Joseph, J. F.; Scotnicki, J. S.; Borella, L.
E.; Adams, L. M. Agents Actions 1991, 34, 223; (b) Sato, G.; Chimoto,
T.; Aoki, T.; Hosokawa, S.; Sumigama, S.; Tsukidate, K.; Sagami, F. J
Toxicol Sci 1999, 24, 165; (c) Naitoh, T.; Kawaguchi, S.; Kakiki, M.;
Ohe, H.; Kajiwara, A.; Horie, T. Xenobiotica 1998, 28, 269; (d) Kagaya,
T.; Kajiwara, A.; Nagato, S.; Akasaka, K.; Kubota, A. J Pharmacol Exp Ther
1996, 278, 243; (e) Oketani, K.; Inoue, T.; Murakami, M. Eur J Pharmacol
2001, 427, 159; (f) Paramashivappa, R.; Phani Kumar, P.; Subba Rao, P.
V.; Srinivasa Rao, A. Bioorg Med Chem Lett 2003, 13, 657; (g) Xie, Y.;
Deng, S.; Chen, Z.; Yan, S.; Landry, D. W. Bioorg Med Chem Lett 2006,
16, 4657; (h) Hutchinson, I.; Jennings, S. A.; Vishnuvajjala, B. R.; Westwell,
A. D.; Stevens, M. F. G. J Med Chem 2002, 45, 744.
[25] Stanetty, P.; Krumpak, B. J Org Chem 1996, 61, 5130.
[26] Al‐Qalaf, F.; Mekheimer, R. A.; Sadek, K. U. Molecules 2008,
13, 2908.
[27] (a) Ben‐Alloum, A.; Bakkas, S.; Soufiaoui, M. Tetrahedron Lett
1997, 38, 6395; (b) Roe, A.; Tuker, W. P. J Heterocycl Chem 1965, 2, 148;
(c) Hutchinson, I.; Stevens, M. F. G.; Westwell, A. D. Tetrahedron Lett 2000,
41, 425; (d) Alagille, D.; Baldwin, R. M.; Tamagnan, G. D. Tetrahedron Lett
2005, 46, 1349; (e) Majo, V. J.; Prabhakaran, J.; Mann, J. J.; Kumar, J. S. D.
Tetrahedron Lett 2003, 44, 8535; (f) Chakraborti, A. K.; Selvam, C.; Kaur,
G.; Bahagat, S. Synlett 2004, 5, 851; (g) Mutsushita, H.; Lee, S. H.; Joung,
M.; Clapham, B.; Janda, K. D. Tetrahedron Lett 2004, 45, 313; (h) Itoh,
T., Nagata, K.; Ishikawa, H.; Ohsawa, Heterocycles 2004, 63, 2769; (i)
Kawashita, Y.; Meba, C.; Hayashi, A. Tetrahedron Lett 2006, 47, 4231; (j)
Praveen, C.; Kumar, K. H.; Muralidharan, D.; Perumal, P. T. Tetrahedron
2008, 64, 2369; (k) Okimoto, M.; Yoshida, T.; Hoshi, M.; Hattori, K.;
Komata, M.; Tomozawa, K.; Chiba, T. Heterocycles 2008, 75, 35; (l) Chou,
C.‐H.; Yu, P.‐C.; Wang, B.‐C. Tetrahedron Lett 2008, 49, 4145; (m)
Chanada, M.; Arup, D. Heterocycles 2007, 71, 1837; (o) Paul, S.; Gupta,
M.; Gupta, R. Synth Commun 2002, 32, 3541; (p) Moghaddam, F. M.;
Bardajee, G. R.; Ismaili, H.; Taimoory, S. M. D. Synth Commun 2006, 36,
2543–2548; (q) Rostamizadeh, S.; Housaini, S. A. Gh. Phosphorus Sulfur
Silicon 2005, 180, 1321.
[28] Moghaddam, F. M.; Bardajee, G. R.; Ismaili, H.; Taimoory, S.
M. D. Synth Commun 2006, 36, 2543.
[29] Bose, D. S.; Idrees, M. J Org Chem 2006, 71, 8261.
[30] Gupta, S. D.; Singh, H. P.; Moorthy, N. S. H. N. Synth
Commun 2007, 37, 4327.
[31] Downer‐Riley, N. K.; Jackson, Y. A. Tetrahedron 2007, 63,
10276.
[32] Pal, S.; Patra, G.; Bhunia, S. Synth Commun 2009, 39, 1196.
[33] Bahrami, K.; Khodaei, M. M.; Naali, F. J Org Chem 2008, 73,
6835.
[7] Wellsa, G.; Loweb, P. R.; Stevensa, M. F. G. ARKIVOC
2000, v, 779.
[8] Kok, S. H. L.; Gambari, R.; Chui, C. H.; Yuen, M. C. W.; Lin,
E.; Wong, R. S. M.; Lau, F. Y.; Cheng, G. Y. M.; Lam, W. S.; Chan, S.
H.; Lam, K. H.; Cheng, C. H.; Lai, P. B. S.; Yu, M. W. Y.; Cheung, F.;
Tanga, J. C.; Chan, A. S. C. Bioorg Med Chem 2008, 16, 3626.
[9] Racane, L.; Kralj, M.; Suman, L.; Stojkovic, R.; Kulenovic, V.
T.; Zamola, G. K. Bioorg Med Chem 2010, 18, 1038.
[10] Jin, G. H.; Li, H.; An, S.; Ryu, J‐H.; Jeon, R. Bioorg Med
Chem Lett 2010, doi: 10.1016/j.bmcl.2010.08.112.
[11] (a) Meroni, G.; Ciana, P.; Meda, C.; Maggi, A.; Santaniello, E.
ARKIVOC 2009, xi, 22; (b) Meroni, G.; Rajabi, M.; Santaniello, E.
ARKIVOC 2009, i, 265.
[34] Mu, X. J.; Zou, J. P.; Zeng, R. S.; Wu, J. C. Tetrahedron Lett
2005, 46, 4345.
[35] Alagille, D.; Baldwin, R. M.; Tamagnan, G. D. Tetrahedron
Lett 2005, 46, 1349.
[12] Satyanarayana, B.; Saravanan, M.; Kumari, K. S.; Lokama-
heshwari, D. P.; Sridhar, C.; Ravishankar, R.; Nageswari, A.; Reddy, P.
P. ARKIVOC 2008, xiv, 109.
[13] Nadeem, S.; Munawar, M. A.; Ahmad, S.; Smiglak, M.; Drab,
D. M.; Malik, K. I.; Amjad, R.; Ashraf, C. M.; Rogers, R. D. ARKIVOC
2010, vii, 19.
[14] Meroni, G.; Rajabi, M.; Ciana, P.; Maggi, A.; Santaniello, E.
ARKIVOC 2010, vi, 53.
[15] Maradolla, M. B.; Allam, S. K.; Mandha, A.; Chandramouli,
G. V. P. ARKIVOC 2008, xv, 42.
[36] Evindar, G.; Batey, R. A. J Org Chem 2006, 71, 1802.
[37] Zhu, C.; Akiyama, T. Synlett 2010; doi: 10.1055/s‐0030–
1258046; Art ID: U05910ST. Advanced online publication: xx.xx.2010.
[38] Londhe, B. S.; Pratap, U. R.; Mali, J. R.; Mane, R. A. Bull
Korean Chem Soc 2010, 31, 2329.
[39] (a) Wirth, T., Ed. Hypervalent Iodine Chemistry: Modern
Developments in Organic Synthesis; Topics in Current Chemistry Series
224; Springer: Berlin, 2003; (b) Zhdankin, V. V.; Stang, P. J. Chem
Rev 2008, 108, 5299; (c) Zhdankin, V. V. Curr Org Synth 2005, 2, 121;
(d) Richardson, R. D.; Wirth, T. Angew Chem Int Ed 2006, 45, 4402;
(e) Wirth, T. Angew Chem Int Ed 2005, 44, 3656; (f) Yoshimura, A.;
Neu, H. M.; Nemykin, V. N.; Zhdankina, V. V. Adv Synth Catal 2010,
352, 1455; (g) Fer, S. S.; Wirth, T. Angew Chem Int Ed 2010, 49,
2786; (h) Zhdankin, V. V.; Stang, P. J. Chem Rev 2008, 108, 5299; (i)
[16] Saha, D.; Adak, L.; Ranu, B. C. Tetrahedron Lett 2010, doi:
10.1016/j.tetlet. 2010.08.063.
[17] Jaseer, E. A.; Prasad, D. J. C.; Dandapat, A.; Sekar, G.
Tetrahedron Lett 2010, 51, 5009.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

September 2012
Solvent‐Free One Pot Synthesis of 2‐Aryl/Heteroarylbenzothiazoles Using Hypervalent
1249
Iodine (III) Reagents
[41] Yusubov, M. S.; Wirth, T. Org Lett 2005, 7, 519 and references
cited their in.
Norrby, P. O.; Petersen, T. B.; Bielawski, M.; Olofsson, B. Chem Eur J
2010, 16, 8251; (j) Merritt, E. A.; Olofsson, B. Angew Chem 2009,
121, 9214; (k) Matveeva, E. D.; Proskurnina, M. V.; Zefirov, N. S. Het-
eroatom Chem 2006, 17, 595.
[40] (a) Bielawski, M.; Zhu, M.; Olofsson, B. Adv Synth Catal
2007, 349, 2610; (b) Bielawski, M.; Aili, D.; Olofsson, B. J Org Chem
2008, 73, 4602; (c) Bielawski, M.; Olofsson, B. Org Synth 2009, 86,
308; (d) Dohi, T.; Ito, M.; Morimoto, K.; Minamitsuji, Y.; Takenaga,
N.; Kita, Y. Chem Commun 2007, 4152.
[42] Kumar, P. Chin J Chem 2009, 27, 1487.
[43] (a) Kumar, P. J Heterocyclic Chem 2010, 47, 1429; doi: 10.1002/
jhet.504; (b) Kumar, P. Chin J Chem 2010, 28, 250; (c) Kumar, P.; Kumar,
A. Bull Korean Chem Soc 2010, 31, 2299; (d) Kumar, P.; Kumar, A.;
Mohan, J.; Makrandi, J. K. Bull Korean Chem Soc 2010, 31, 3304; (e)
Kumar, P.; Kumar, S.; Hussain, K.; Kumar, A. Chin Chem Lett 2011, 22,
37; (f) Kumar, P.; Kumar, A. Chin Chem Lett 2010, 21, 1287.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet