An effcient synthesis of 2-aminobenzoxazoles and 2-aminobenzothiazazoles from 2-aminophenols or 2-aminothiophenols and isoselenocyanates

Article abstract of DOI:10.3987/COM-10-11987

An expeditious method to access 2-aminobenzoxazoles and 2-aminobenzothiazoles from various substituted 2-aminophenols and 2-aminothiophenols, respectively, with isoselenocyanates in a one pot procedure is reported. Elemental Se precipitates nearly quantitatively in the reaction without any deselenizing agent and it can be reused. A possible mechanism for the formation of the target products is proposed. The Japan Institute of Heterocyclic Chemistry.

Full text of DOI:10.3987/COM-10-11987

HETEROCYCLES, Vol. 81, No. 9, 2010
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HETEROCYCLES, Vol. 81, No. 9, 2010, pp. 2087 - 2096. © The Japan Institute of Heterocyclic Chemistry
Received, 7th June, 2010, Accepted, 30th July, 2010, Published online, 3rd August, 2010
DOI: 10.3987/COM-10-11987
AN EFFCIENT SYNTHESIS OF 2-AMINOBENZOXAZOLES AND
2-AMINOBENZOTHIAZAZOLES FROM 2-AMINOPHENOLS OR
2-AMINOTHIOPHENOLS AND ISOSELENOCYANATES
Yuanyuan Xie,* Fan Zhang, Xiaodong Chen, and Jianjun Li
Key Laboratory of Pharmaceutical Engineering of Ministry of Education, College
of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou
310014, P.R. China Phone: +86 (571) 88320867 Fax: +86 (571) 88320867 E-mail:
pharmlab@zjut.edu.cn
Abstract – An expeditious method to access 2-aminobenzoxazoles and
2-aminobenzothiazoles from various substituted 2-aminophenols and
2-aminothiophenols, respectively, with isoselenocyanates in a one pot procedure
is reported. Elemental Se precipitates nearly quantitatively in the reaction without
any deselenizing agent and it can be reused. A possible mechanism for the
formation of the target products is proposed.
INTRODUCTION
In the past two decades, the chemistry of organoselenium compounds has attracted much attention
because of their importance as synthetic tools.1 Remarkable jobs have been done by Heimgartner’s group
and other research groups for the utility of isoselenocyanates as building blocks in the synthesis of
Se-containing heterocycles.2
However, reactions with isoselenocyanates to give corresponding non-Se-containing heterocycles have
not been studied profoundly. So far as we know, Fernández-Bolaños and his co-workers discovered the
phenomenon that elemental Se precipitated from unprotected glycopyranosyl selenoureas which were
synthesized from isoselenocyanates and glycopyranosylamines to give bicyclic isoureas.3 Very recently,
we have reported the preparation of 2-aminobenzimidazoles by the reaction of isoselenocyanates and
o-phenylenediamines.4
2-Aminobenzoxazole and 2-aminobenzothiazole are known as biologically active compounds in many
pharmaceuticals and agrochemicals.5 For example, 2-aminobenzoxazole shows activity against inhibitors
or modulators of histamine receptors and is regarded as a drug candidate for the treatment of HIV,
neurodegeneration, and inflammatory diseases.6

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Therefore, there has been an enhanced interest in the synthesis of 2-aminobenzoxazoles and
2-aminobenzothiazoles. The traditional synthetic approach of the formers involves treatment of
2-aminophenol with isothiocyanates to obtain the corresponding thioureas, which later undergo a
cyclodesulfurization step with the assistance of diverse desulfurizing agents.7 Reported routes to
2-aminobenzothiazoles include: i) reacting 2,2’-diaminodiphenyl disulfide with isothiocyanates,8 ii)
copper(I)-catalyzed reaction of 2-iodoaniline with isothiocyanates,9 and iii) microwave promoted reaction
of 2-chlorobenzothiazole with an amine.10 When an isothiocyanate is invovled as one of the starting
material, the methods usually need desulfurizing agents. These desulfurizing agents are mostly converted
to acidic gases, compounds with terrible odor, or heavy metals. We also notice that these methods often
need longer reaction time, lead to problems with complex workup or suffer from low yields.
Because of the similarity on structural and chemical properties and especially stronger leaving tendency
of selenium, we decided to develop analogous reactions with isoselenocyanates, and herein to report an
efficient one-pot procedure for the synthesis of two important classes of compounds,
2-aminobenzoxazoles and 2-aminobenzothiazoles.
RESULTS AND DISCUSSION
Phenyl isoselenocyanates and cyclohexyl isoselenocyanate have been prepared following
Fernández-Bolaños’s procedure.11 Equimolar amounts of a 2-aminophenol and an isoselenocyanate were
then added to DMF. To our great surprise, 2-aminobenzoxazole was obtained in excellent yield and
elemental Se was precipitated without any deselenizing agent. The precipitation made the post workup
extremely easy: only a filtration was needed to separate Se from the mixture. The filtrate was
concentrated and purified chromatographically to give 2-aminobenzoxazole. Futhermore, we optimized
the reaction condition of the cyclocondensation of 2-aminophenol 2 and 1-isoselenocyanato-4-
o
methoxybenzene 1c. The results showed that DMF is the appropriate solvent, and 70 C was the optimal
reaction temperature to give 3c in 96% yield, while lower yields were obtained in pyridine at 70 oC (82%)
and in THF under reflux (81%). Other solvents such as CH2Cl2, toluene and AcOEt gave no desired
product. It might due to DMF provided an alkaline condition that enhanced the attack capability of the
amino group of 2-aminophenol.
Under the optimized conditions, a variety of 2-aminobenzoxazoles were prepared. As shown in Table 1,
phenyl isoselenocyanates containing both electron donating and electron withdrawing groups,
respectively, gave 2-aminobenzoxazoles in good to excellent yields. The effect of different substituent on
the 2-aminophenol was also considered. With the strong electron withdrawing effect of the nitro group,
the nucleophilic tendency of the amino group was largely reduced and the total reaction time was
prolonged to 14 h. However, the precipitation of Se promoted the reaction proceeding and gave target
products in good yields.

HETEROCYCLES, Vol. 81, No. 9, 2010
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Table 1. Synthesis of 2-aminobenzoxazole from isoselenocyanates
NH2
OH
R1
NH
N
O
DMF
Se
R1
C
70 oC
N
R2
R2
2
3a-3j
1
Entry
R1
Ph
R2
H
H
H
H
NO2
NO2
NO2
Cl
Product
Reaction time [h]a
Yield [%]b
1
2
3
4
5
6
7
8
9
10
3a
3b
3c
3d
3e
3f
3g
3h
3i
6.5
6.5
6
5.5
14
14
14
6
85, 83c
90
4-MeC6H4
4-MeOC6H4
4-ClC6H4
Ph
2-MeC6H4
4-MeOC6H4
Ph
96
83
77
83
84
79
91
88
2-MeC6H4
4-MeOC6H4
Cl
Cl
7
8
3j
a) Monitored by TLC, until 2-aminophenol was fully consumed.
b) Yield of isolated product after column chromatography.
c) Reproduced isoselenocyanate.
The successful preparation of 2-aminobenzoxazoles encouraged us to apply this methodology for the
synthesis of 2-aminobenzothiazoles. As expected, various 2-aminobenzothiazoles were prepared
successfully. A lower reaction temperature (40 oC) was needed, which might be the result of the stronger
nucleophilicity of the SH group. As can be seen from Table 2, different substituents were also well
tolerated in this reaction. Electron donating and electron withdrawing groups on phenyl isoselenocyanates
as well as cyclohexyl isoselenocyanate performed well in this reaction and gave excellent yields.
Table 2. Synthesis of 2-aminobenzothiazole from isoselenocyanates
NH2
SH
R1
NH
N
DMF
Se
R1
C
40 oC
N
S
1
4
3k-3p
Entry
R1
Ph
Product
3k
Reaction time [h]a
Yield [%]b
1
2
3
4
5
6
6
6.5
5.5
5
6
12
89, 88c
91
3-MeC6H4
2-EtC6H4
4-MeOC6H4
4-ClC6H4
3l
3m
3n
3o
3p
78
90
82
73
cyclohexyl
a) Monitored by TLC, until 2-aminothiophenol was fully consumed.
b) Yield of isolated product after column chromatography.
c) Reproduced isoselenocyanate.

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Since a variety of 2-aminobenzoxazoles and 2-aminobenzothiazoles were prepared by this method, we
were eager to know the recovery rate of Se precipitated in the reaction. With great success, the recovery
rate was 95-97%, which means that Se was nearly quantitatively recovered. Isoselenocyanates could be
reproduced from these selenium, thus to cut the waste to the minimum (Table 1, Entry 1; Table 2, Entry
1).
In the light of all these results, two possible reaction mechanisms are proposed in Scheme 1. In both cases,
a selenourea 5 was generated by the reaction of 2-aminophenol or 2-aminothiophenol with
isoselenocyanate. In path I, 5 was then converted to product 3 through an intramolecular cyclization with
the assistant of O2. Another popular mechanism12 for this type of reaction shown as path II involved the
formation of a carbodiimide intermediate 7, which cyclized spontaneously to give the desired product 3.
An experiment under N2 atmosphere had been carried out to determine the necessity of the O2. According
to our results, only selenourea 5 was formed after 36 h, which means that the reaction does not lead to 3
without the help of O2, thus supporting path I.
H
H
R N C Se
NH2
XH
N
N
1
R
Se
DMF
XH
2 or 4
5
(X = O, S)
R
H
N
H
N
N
HN
R
1/2 O2
SeH
X
SeH
Se H2O
XH
Path I
Path II
N
X
6
5
NH
R
N
C
R
H2Se
N
3
XH
7
Scheme 1. Possible mechanism for the synthesis of 2-aminobenzoxazole and 2-aminobenzothiazole
In summary, we have developed a novel one-pot procedure for the synthesis of 2-aminobenzoxazoles and
2-aminobenzothiazoles by reacting isoselenocyanates with 2-aminophenol or 2-aminothiophenol without
using a deselenizing agent. Compared with traditional routes, this method provides a high yield of the
target products with both electron-donating and electron-withdrawing groups. The reaction was
performed under mild conditions, and the key material, i.e. the isoselenocyanates, could be reproduced
from the precipitated elemental Se, which largely simplifies the purification procedures and minimizes
the harm to the environment. The method also widens the application of isoselenocyanates as important

HETEROCYCLES, Vol. 81, No. 9, 2010
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reagents. An experiment was carried out to determine the reaction mechanism and the oxygen-involved
intramolecular cyclization pathway was confirmed.
EXPERIMENTAL
General. Mp: Büchi B-540 apparatus; uncorrected. IR Spectra: Nicolet Avatar-370 spectrometer, in KBr;
1
13
in cm-1. H- and C-NMR Spectra: Varian Mercury Plus-400 instrument, in (d6) DMSO at 400 and 100
MHz, resp.;  in ppm, J in Hz. ESI-MS: Thermo Finnigan LCQ Advantage instrument; in m/z. HRMS:
Agilent 6210 TOF instrument.
General Procedure for the Synthesis of 2-Aminobenzoxazoles. (Take 3a for example). Phenyl
isoselenocyanate (0.182g, 1 mmol) and 2-aminophenol (0.109g, 1 mmol) were added to DMF (20 mL)
o
with magnetic stirring. The mixture was heated to 70 C for 6.5 h. When the reaction was completed as
monitored by TLC, the mixture was cooled to rt. The solid Se was filtered off and washed with AcOEt
(10 mL). The recovery rate of Se is 95% - 97%. The combined filtrate was concentrated in vacuo and the
residue was chromatographed on silica gel (hexane:AcOEt = 1:1) to give white solid
N-Phenylbenzo[d]oxazol-2-amine 3a (0.179 g, 85%).
General Procedure for the Synthesis of 2-Aminobenzothiazoles. (Take 3k for example). Phenyl
isoselenocyanate (0.182 g, 1 mmol) and 2-aminothiophenol (0.125 g, 1 mmol) were added to DMF (20
mL) with magnetic stirring. The mixture was heated to 40 oC for 6 h. When the reaction was completed as
monitored by TLC, the mixture was cooled to rt. The solid Se was filtered off and washed with AcOEt
(10 mL). The combined filtrate was concentrated in vacuo and the residue was chromatographed on silica
gel (hexane :AcOEt = 1 :1) to give white solid N-phenylbenzo[d]thiazol-2-amine 3k (0.201 g, 89%).
Procedure for Control Experiment. Phenyl isoselenocyanate (0.182 g, 1 mmol) and 2-aminophenol (0.109
g, 1 mmol) were added successively to DMF (20 mL) with magnetic stirring under an N2 atmosphere.
o
The mixture was heated to 70 C and monitored by TLC. The reaction time was prolonged to 36 h, no
product 3a was detected.
N-Phenylbenzo[d]oxazol-2-amine (3a; Table 2).
White solid. Mp 176.6–177.1 oC. Lit.,12 mp 176–178 oC. IR (KBr): 3379, 3154, 3105, 3039, 1928, 1662,
1
1572, 1490, 1282, 1217, 971, 738, 681 cm-1. H-NMR (400 MHz, DMSO-d6): 10.62 (s, 1H); 7.77(d, J =
8.4, 2H); 7.45-7.50 (m, 2H); 7.38 (t, J = 8.4, 2H ); 7.23 (t, J =8.4, 1H); 7.14 (t, J = 7.2, 1H); 7.04 (t, J =
7.2, 1H). 13C-NMR (400 MHz, DMSO-d6): 157.9 (s); 147.0 (s); 142.4 (s); 138.74 (s); 128.9 (2×CH);
123.9 (d); 122.1 (d); 121.6 (d); 117.5 (2×CH); 116.6 (d); 108.9 (d). ESI-MS: 211 (M-H) -.
N-(4-Methylphenyl)benzo[d]oxazol-2-amine (3b; Table 2).

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White solid. Mp 172.3–172.8 oC. Lit.,13 mp 169–171 oC. IR (KBr): 3382, 3161, 1664, 1574, 1460, 1401,
1
1227, 820, 737 cm-1. H-NMR (400 MHz, DMSO-d6): 10.50 (s, 1H); 7.64 (d, J = 8.4, 2H); 7.43-7.48(m,
13
2H); 7.17-7.23 (m, 3H); 7.12 (t, J = 7.2 , 1H); 2.28 (s, 3H). C-NMR (400 MHz, DMSO-d6): 158.1 (s);
147.0 (s); 142.5 (s); 136.2 (s); 131.0 (s); 129.3 (2×CH); 123.9 (d); 121.5 (d); 117.6 (2×CH); 116.4 (d);
108.8 (d); 20.3(q). ESI-MS: 225 (M-H)-.
N-(4-Methoxyphenyl)benzo[d]oxazol-2-amine (3c; Table 2).
White solid. Mp 135.4–136.5 oC. Lit.,12 mp 136–138 oC. IR (KBr): 3383, 2994, 2839, 1675, 1581, 1512,
1
1460, 1232, 1033, 822, 742 cm-1. H-NMR (400 MHz, DMSO-d6): 10.41 (s, 1H); 7.68 (d, J = 8.0, 2H);
7.42-7.47 (m, 2H); 7.21 (t, J = 7.2, 1H); 7.10 (t, J = 7.2, 1H); 6.97 (d, J = 9.2, 2H); 3.75 (s, 3H).
13C-NMR (400 MHz, DMSO-d6): 159.4 (s); 156.1 (s); 147.9 (s); 142.1 (s); 131.0 (s); 124.2 (d); 121.4 (d),
121.1 (2×CH); 116.5 (d); 114.5 (2×CH); 109.1 (d); 55.5 (q). ESI-MS: 241 (M-H) -.
N-(4-Chlorophenyl)benzo[d]oxazol-2-amine (3d; Table 2).
o
White solid. Mp 153.1–154.5 C. IR (KBr): 3428, 3157, 1663, 1575, 1491, 1400, 1230, 738 cm-1.
1H-NMR (400 MHz, DMSO-d6): 10.79 (s, 1H); 7.79 (d, J = 8.4, 2H); 7.46-7.52 (m, 2H); 7.44 (d, J = 8.4,
13
2H); 7.24 (t, J = 7.2, 1H); 7.15 (t, J = 7.2, 1H). C-NMR (400 MHz, DMSO-d6): 157.7 (s); 147.0 (s);
142.2 (s); 137.7 (s); 128.9 (2×CH); 125.7 (s); 124.1 (d); 121.9 (d); 119.1 (2×CH); 116.7 (d); 109.1 (d).
ESI-MS: 245(M-H)- ; 247 (M+2-H)-.
5-Nitro-N-phenylbenzo[d]oxazol-2-amine (3e; Table 2).
o
o
Yellow solid. Mp 238.5–239.4 C. Lit.,13 mp 236 C. IR (KBr): 3109, 3041, 2882, 1720, 1601, 1530,
1
1336, 1266, 978, 875, 813, 734 cm-1. H-NMR (400 MHz, DMSO-d6): 11.04 (s, 1H), 8.24 (d, J = 2.4,
1H); 8.08 (dd, J = 2.4, 8.8, 1H); 7.72-7.77 (m, 3H); 7.42 (t, J = 7.6, 2H); 7.10 (t, J = 7.6, 1 H). 13C-NMR
(400 MHz, DMSO-d6): 160.0 (s); 151.3 (s); 144.5 (s); 143.3 (s); 137.9 (s); 128.9 (2×CH); 122.8 (d);
118.1 (3×CH); 111.4 (d); 109.1 (d). ESI-MS: 256 (M+H)+.
5-Nitro-N-(2-methylphenyl)benzo[d]oxazol-2-amine (3f; Table 2).
o
Yellow solid. Mp 171.2–172.1 C. IR (KBr): 3419, 1663, 1598, 1525, 1463, 1346, 1274, 1241, 877, 737
cm-1. 1H-NMR (400 MHz, DMSO-d6): 10.17 (s, 1H); 8.13 (s, 1H); 8.03-8.06 (m, 1H); 7.68-7.72 (m, 2H);
7.28 (t, J = 8.0, 2H); 7.16 (t, J = 7.2, 1H); 2.31 (s, 3H). 13C-NMR (400 MHz, DMSO-d6): 161.8 (s); 151.9
(s); 144.5 (s); 143.6 (s); 135.7 (d); 131.3 (s); 130.6 (s); 126.5 (d); 125.4 (d); 123.8 (d); 117.6 (d); 111.1
(d); 109.1 (d); 17.7 (q). HRMS: calcd for C14H10N3O3: 268.0722; found: 268.0730.
N-(4-Methoxyphenyl)-5-nitrobenzo[d]oxazol-2-amine (3g; Table 2).

HETEROCYCLES, Vol. 81, No. 9, 2010
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Yellow solid. Mp 203.2–204.7 oC. IR (KBr): 3400, 3114, 1672, 1584, 1524, 1511, 1345, 1248, 878, 818,
1
739 cm-1. H-NMR (400 MHz, DMSO-d6): 10.83 (s, 1H); 8.20 (d, J = 2.4, 1H); 8.06 (dd, J = 2.4, 8.8,
1H); 7.70 (d, J = 8.8, 1H); 7.65 (d, J = 9.2, 2H); 6.99 (d, J = 9.2, 2H); 3.76 (s, 3H). 13C-NMR (400 MHz,
DMSO-d6): 160.4 (s); 155.2 (s); 151.5 (s); 144.5 (s); 143.6 (s); 131.0 (s); 119.8 (2×CH); 117.8 (d); 114.3
(2×CH); 111.1 (d); 109.0 (d); 55.2 (q). HRMS: calcd for C14H10N3O4: 284.0671; found: 284.0684.
5-Chloro-N-phenylbenzo[d]oxazol-2-amine (3h; Table 2).
o
o
Grey solid. Mp 203.4–204.9 C. Lit.,14 mp 212–213 C. IR (KBr): 3481, 3414, 3124, 1679, 1618, 1577,
1
1446, 1401, 1230, 980, 788 cm-1. H-NMR (400 MHz, DMSO-d6): 10.79 (s, 1H); 7.73-7.75 (m, 2 H);
13
7.51-7.53 (m, 2H); 7.37-7.41 (m, 2H); 7.16 (dd, J = 2.0, 8.4, 1H); 7.06 (t, J = 7.6, 1 H). C-NMR (400
MHz, DMSO-d6): 159.1 (s); 145.8 (s); 144.0 (s); 138.3 (s); 128.9 (2×CH); 128.1 (s); 122.4 (d); 121.2 (d);
117.8 (2×CH); 116.2 (d); 110.0 (d). ESI-MS: 243 (M-H)- ; 245 (M+2-H)-.
5-Chloro-N-(2-methylphenyl)benzo[d]oxazol-2-amine (3i; Table 2).
White solid. Mp 195.3–196.4 oC. IR (KBr): 3128, 3028, 2893, 1660, 1577, 1459, 1358, 1236, 1191, 972,
1
846, 763 cm-1. H-NMR (400 MHz, DMSO-d6): 9.88 (s, 1H); 7.73-7.75 (m, 1H); 7.47 (d, J = 8.4, 1H);
7.41 (d, J = 2.4, 1H); 7.26 (t, J = 7.2, 2H); 7.10-7.14 (m, 2H); 2.30 (s, 3H). 13C-NMR (400 MHz,
DMSO-d6): 160.8 (s); 146.4 (s); 144.2 (s); 136.1 (s); 130.8 (s); 130.5 (d); 128.0 (s); 126.4 (d); 124.9 (d);
123.3 (d); 120.7 (d); 115.9 (d); 109.9 (d); 17.7 (q). HRMS: calcd for C14H10ClN2O: 257.0482; found:
257.0489.
5-Chloro-N-(4-methoxyphenyl)benzo[d]oxazol-2-amine (3j; Table 2).
White solid. Mp 182.3–182.9 oC. IR (KBr): 3148, 3006, 2936, 1689, 1578, 1513, 1492, 1462, 1259, 1035,
1
972, 829, 794 cm-1. H-NMR (400 MHz, DMSO-d6): 10.56 (s, 1H); 7.63 (d, J = 8.8, 2H); 7.46-7.49 (m,
13
2H), 7.12 (dd, J = 2.4, 8.4, 1H); 6.97 (d, J = 7.2, 2H); 3.75 (s, 3H). C-NMR (400 MHz, DMSO-d6):
159.5 (s); 154.9 (s); 145.9 (s); 144.2 (s), 131.4 (s); 128.0 (s); 120.9 (d); 119.5 (2×CH); 116.0 (d); 114.2
(2×CH); 109.8 (d); 55.2 (q). ESI-MS: 273 (M-H)- ; 275 (M+2-H)-.
N-Phenylbenzo[d]thiazol-2-amine (3k; Table 3).
o
o
White solid. Mp 160.4–161.5 C. Lit.,15 mp 160–162 C. IR (KBr): 3422, 3189, 3129, 3053, 2936, 1626,
1573, 1467, 1447, 1249, 922, 745, 721 cm-1. 1H-NMR (400 MHz, DMSO-d6): 10.48 (s, 1H); 7.79-7.82 (m,
13
3H); 7.61 (d, J = 8.4, 1H); 7.31-7.39 (m, 3H); 7.16 (t, J = 7.2, 1H), 7.03 (t, J = 7.2, 1H). C-NMR (400
MHz, DMSO-d6): 161.6 (s); 152.1 (s); 140.6 (s); 130.0 (s); 129.0 (2×CH), 125.9 (d); 122.3 (d); 122.0 (d);
121.1 (d); 119.2 (d); 117.7 (2×CH). ESI-MS: 227 (M+H)+.

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N-(3-Methylphenyl)benzo[d]thiazol-2-amine (3l; Table 3).
White solid. Mp 120.3–121.1 oC. Lit.,16 mp 124 oC. IR (KBr): 3447, 2922, 1626, 1575, 1448, 1276, 1250,
1
746, 721 cm-1. H-NMR (400 MHz, DMSO-d6): 10.40 (s, 1H); 7.80 (d, J = 8.0, 1H); 7.56-7.65 (m, 3H);
7.33 (t, J = 7.2, 1H); 7.25 (t, J = 7.6, 1H); 7.16 (t, J = 8.0, 1H); 6.85 (d, J = 7.6, 1H); 2.33 (s, 3H).
13C-NMR (400 MHz, DMSO-d6): 161.6 (s); 152.1 (s); 140.6 (s); 138.2 (d); 130.0 (s); 128.9 (d); 125.9 (d);
122.9 (d); 122.2 (d); 121.0 (d); 119.2 (s); 118.3 (d); 115.1 (d); 21.3 (q). ESI-MS: 241 (M+H)+.
N-(2-Ethylphenyl)benzo[d]thiazol-2-amine (3m; Table 3).
White solid. Mp 152.5–153.9 oC. IR (KBr): 3446, 3176, 2964, 2868, 1612, 1595, 1562, 1446, 1265, 1018,
1
752, 725 cm-1. H-NMR (400 MHz, DMSO-d6): 9.69 (s, 1H); 7.72-7.76 (m, 2H); 7.46 (d, J = 7.6, 1H);
7.24-7.30 (m, 3H); 7.15-7.19 (m, 1H); 7.07-7.11 (m, 1 H); 2.69 (q, J = 7.6, 2H); 1.14 (t, J = 7.6, 3H).
13C-NMR (400 MHz, DMSO-d6): 164.9 (s); 152.0 (s); 138.1 (s); 137.2 (d); 130.2 (s); 129.0 (d); 126.6 (d);
125.7 (d); 125.4 (d); 124.5 (d); 121.6 (d); 121.0 (d); 118.5 (s); 23.9 (t); 14.4 (q). ESI-MS: 255 (M+H)+.
N-(4-Methoxyphenyl)benzo[d]thiazol-2-amine (3n; Table 3).
White solid. Mp 161.4–162.5 oC. Lit.,17 mp 158–160 oC. IR (KBr): 3445, 2836, 1620, 1572, 1511, 1453,
1232, 1037, 826, 745 cm-1. 1H-NMR (400 MHz, DMSO-d6): 10.29 (s, 1H); 7.77 (d, J = 7.6, 1H); 7.69 (d,
J = 8.8, 2H); 7.55 (d, J = 7.6, 1H); 7.31(t, J = 7.6, 1H); 7.12 (t, J = 7.6, 1H), 6.96 (d, J = 8.8, 2H); 3.75 (s,
3H). 13C-NMR (400 MHz, DMSO-d6): 162.0 (s); 154.6 (s); 152.3 (s); 134.0 (s); 129.9 (s); 125.8 (d);
121.9 (d); 121.0 (d); 119.6 (2×CH); 118.9 (d); 114.2 (2×CH); 55.2 (q). ESI-MS: 257 (M+H)+.
N-(4-Chlorophenyl)benzo[d]thiazol-2-amine (3o; Table 3).
o
White solid. Mp 194.5–195.2 oC. Lit.,18 mp 195–196 C. IR (KBr): 3445, 3170, 3065, 2845, 1609, 1561,
1448, 1269, 1216, 1056, 918, 841, 751 cm-1. 1H-NMR (400 MHz, DMSO-d6): 10.08 (s, 1H); 8.33 (d, J =
8.0, 1H); 7.82 (d, J = 7.6, 1H); 7.58 (d, J = 8.4, 1H); 7.53 (dd, J = 1.2, 8.0, 1H); 7.41 (td, J = 1.2, 8.0,
1H); 7.33 (td, J = 1.2, 8.0, 1H); 7.13-7.19 (m, 2H). 13C-NMR (400 MHz, DMSO-d6): 162.8 (s); 151.1 (s);
137.4 (s); 129.7 (s); 127.8 (2×CH); 125.8 (d); 124.8 (d); 124.3 (s); 123.4 (2×CH); 122.3 (d); 121.1 (d).
ESI-MS: 259 (M-H)- ; 261 (M+2-H)-.
N-Cyclohexylbenzo[d]thiazol-2-amine (3p; Table 3).
White solid. Mp 103.1 - 104.5 oC. Lit.,19 mp 103–104 oC. IR (KBr): 3456, 2929, 2852, 1608, 1567, 1445,
1365, 1275, 885, 752 cm-1. 1H-NMR (400 MHz, DMSO-d6): 7.94 (d, J = 7.6, 1H); 7.63 (d, J = 8.0, 1H);
7.37 (d, J = 8.0, 1H); 7.19 (t, J = 7.6, 1H); 6.99 (t, J = 7.6, 1H); 3.68 v 3.72 (m, 1H), 1.97–2.00 (m, 2H),
13
1.70-1.75 (m, 2H); 1.56-1.60 (m, 1H); 1.17-1.38 (m, 5H). C-NMR (400 MHz, DMSO-d6): 165.1 (s);
152.8 (s); 130.1 (s); 125.4 (d); 120.7 (d); 120.6 (d); 117.8 (d); 52.7 (d); 32.3 (2CH2); 25.3 (t); 24.4

HETEROCYCLES, Vol. 81, No. 9, 2010
2095
(2CH2). ESI-MS: 233 (M+H)+.
1-(2-hydroxyphenyl)-3-phenylselenourea (5a).
o
1
Pink solid. Mp 153–155 C. IR (KBr): 3302, 3186, 3114, 2932, 1600, 1546, 1492 cm-1. H-NMR (400
MHz, DMSO-d6): 9.99 (s, 1H); 9.77 (s, 1H); 9.42 (s, 1H); 7.59 (d, J = 7.6 Hz, 1H); 7.43 (d, J = 7.6 Hz,
2H); 7.32 (t, J = 7.6 Hz, 2H); 7.16 (t, J = 7.6 Hz, 1H); 7.03 (t, J = 8.0 Hz, 1H); 6.86 (d, J = 8.0 Hz, 1H);
6.76 (t, J = 7.6 Hz, 1H). 13C-NMR (400 MHz, DMSO-d6): 177.7 (s); 150.7 (s); 139.4 (s); 128.4 (2CH);
126.9 (d); 126.7 (d); 126.5 (s); 125.2 (d); 124.8 (2CH); 118.5 (d); 115.8 (d). ESI-MS: 291 (M-H)-.
HRMS: calcd for C13H11N2OSe: 291.0037; found: .291.0041
ACKNOWLEDGEMENTS
We are grateful to the National Natural Science Foundation of China (No 20906083 and No 20806073)
and Natural Science Foundation of Zhejiang Province (No Y40900488) for financial support.
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