Metal-free or transition-metal-catalyzed one-pot synthesis of 2-aminobenzothiazoles

Article abstract of DOI:10.1080/17415993.2017.1337771

A series of 2-aminobenzothiazoles were synthesized by using 2-halogen-substituted anilines (halogen = Cl, Br, I) and dithiocarbamates in the presence of KOt-Bu. This simple and efficient protocol lets the reactions undergo in a smooth and rapid way to afford the corresponding 2-aminobenzothiazoles in good yields. It is noteworthy that the present process allows the construction of 2-aminobenzothiazoles from a wide range of 2-halogen-substituted aniline derivatives, including substituted 2-iodoanilines, 2-bromoanilines and 2-chloroanilines.

Full text of DOI:10.1080/17415993.2017.1337771

Journal of Sulfur Chemistry
ISSN: 1741-5993 (Print) 1741-6000 (Online) Journal homepage: http://www.tandfonline.com/loi/gsrp20
Metal-free or transition-metal-catalyzed one-pot
synthesis of 2-aminobenzothiazoles
Wan Xu, Meng-Tian Zeng, Min Liu, Xing Liu, Cai-Zhu Chang, Hui Zhu & Zhi-
Bing Dong
To cite this article: Wan Xu, Meng-Tian Zeng, Min Liu, Xing Liu, Cai-Zhu Chang, Hui Zhu
& Zhi-Bing Dong (2017): Metal-free or transition-metal-catalyzed one-pot synthesis of 2-
aminobenzothiazoles, Journal of Sulfur Chemistry, DOI: 10.1080/17415993.2017.1337771
To link to this article: http://dx.doi.org/10.1080/17415993.2017.1337771
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Date: 14 June 2017, At: 01:19

JOURNAL OF SULFUR CHEMISTRY, 2017
https://doi.org/10.1080/17415993.2017.1337771
Metal-free or transition-metal-catalyzed one-pot synthesis of
2-aminobenzothiazoles
Wan Xua, Meng-Tian Zenga, Min Liua, Xing Liua, Cai-Zhu Changa, Hui Zhua and
Zhi-Bing Donga,b
aSchool of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan, People’s
Republic of China; bKey Laboratory of Green Chemical Process, Ministry of Education, Wuhan Institute of
Technology, Wuhan, People’s Republic of China
ABSTRACT
ARTICLE HISTORY
Received 8 April 2017
Accepted 29 May 2017
A series of 2-aminobenzothiazoles were synthesized by using 2-
halogen-substituted anilines (halogen = Cl, Br, I) and dithiocarba-
mates in the presence of KOt-Bu. This simple and efficient pro-
tocol lets the reactions undergo in a smooth and rapid way to
afford the corresponding 2-aminobenzothiazoles in good yields.
It is noteworthy that the present process allows the construc-
tion of 2-aminobenzothiazoles from a wide range of 2-halogen-
substituted aniline derivatives, including substituted 2-iodoanilines,
2-bromoanilines and 2-chloroanilines.
KEYWORDS
Copper; palladium; aniline;
2-aminobenzothiazoles;
synthesis
X=I, metal free condition;
X=Br, Cat.=CuO (8mmol%);
R
2
NH
X
2
S
N
R
N
S
2
X=Cl, Cat.=Pd(PPh
) (5mmol%)
R
3
4
2
R
+
R
N
1
1
S
R
DMSO, 100°C
KOt-Bu,
2
Yields: 53-93%; 13 examples
R
=Cl, Br, Me, OMe;
R
=Me, Et
2
1
X=I, Br, Cl
1. Introduction
As a privileged scaffold, substituted benzothiazoles have been widely known as promi-
nent agents in many pharmaceuticals that demonstrate remarkable biological activities
such as antibacterial and antimicrobial properties [1–7]; they are also popular construc-
tion units in fatty acid amide hydrolase inhibitors [8] and antitumor agents (Figure 1).
Moreover, benzothiazole-based compounds have been applied in other fields, for exam-
ple as ratiometric fluorescent pH indicators [9]. Thus, continuous efforts have been made
to develop new methods for the construction of these compounds. Generally, the typ-
ical approach to synthesize the benzothiazoles is mostly based on the condensation of
2-aminothiophenenols with aldehydes [10–17], carboxylic acids [18,19] or esters [20,21],
and on the oxidative intramolecular cyclization of thiobenzanilides [22–26]. Other pro-
cedures such as cyclization of N-(2-halo)arylthioureas or direct intramolecular C–S bond
CONTACT Zhi-Bing Dong
Engineering, Wuhan Institute of Technology, Wuhan 430205, People’s Republic of China,
dzb04982@wit.edu.cn, dzb04982@163.com
School of Chemistry and Environmental
Key Laboratory of Green
Chemical Process, Ministry of Education, Wuhan Institute of Technology, Wuhan 430205, People’s Republic of China
© 2017 Informa UK Limited, trading as Taylor & Francis Group

2
W. XU ET AL.
HO2C
N
OMe
OMe
F3C
N
N
S
F
N
S
O
Zoplrestat
antiumor agent, PMX610
Me
H
N
N
O
N
O
N
S
Me
(R)-CVT-3501
Figure 1. Examples of bioactive 2-aminobenzothiazoles.
formations via C–H functionalization of N-arylthioureas under transition metal catalysis
broaden the synthesis methods [27–34]. Despite the numerous efforts toward the synthe-
sis of benzothiazoles, the methods reported in the literature often need expensive metal
catalysts, ligands and amount of toxic oxidants or multistep reactions, which limit the syn-
thetic application. For this reason, more attention has been devoted to one-pot synthetic
methods because of their simplicity. On the other hand, due to their low cost and ready
availability, the 2-haloanilines are attractive starting materials for the synthesis of ben-
zothiazoles [35–43]. Hereby, we would like to report a one-pot protocol for the synthesis
of 2-aminobenzothiazoles by metal-free/transition metal (copper or palladium) catalysis
conditions, starting from 2-iodoanilines, 2-bromoanilines and 2-chloroanilines.
2. Results and discussion
At the outset of the studies, 2-iodoaniline 1a and dithiocarbamates 2a were selected as
model substrates due to the high polarizability of the C–I bond. We were pleased to find
that 2-(dimethylamino)benzothiazole 3A could be obtained in 31% yield in the presence
of KOH and DMSO at 100°C for 4.5 h (Table 1, entry 1). Encouraged by this result, fur-
ther investigation was conducted to optimize the reaction conditions, and the results are
summarized in Table 1. Some organic and inorganic bases were screened for this trans-
formation, such as NEt3, NaH, CH3ONa, Cs2CO3, NaOH and KOt-Bu (Table 1, entries
2–6). The results showed that KOt-Bu provided good yields and proved to be the most
suitable base. No desired product was detected by GC-MS in the absence of any addi-
tive (Table 1, entry 7); the result revealed that KOt-Bu was crucial for this transformation.
Solvent, temperature and the base quantity were further investigated. When shifting the
solvent to DMAC, DMF or CH3CN (Table 1, entries 8–10), only a trace amount of desired
product was detected, and the use of PhCH3 gave the product in moderate yield of 59%
(Table 1, entry 12). The best results were also obtained using a reaction temperature of
100°C (Table 1, entries 6, 14–17). The excess of KOt-Bu proved crucial for full conversion
(Table 1, entries 19–20). One or two equivalent of base loading gave moderate yield of the

JOURNAL OF SULFUR CHEMISTRY
3
Table 1. Screening reaction conditions for 2-iodoaniline and dithiocarbamate.a
NH2
N
S
S
N
conditions
+
N
I
S
3A
1a
2a
Entry
Base(equiv)
Solvent
Temp (°C)
Yield (%)b
1
2
3
4
5
6
7
8
KOH
NaH
CH3ONa
Cs2CO3
NaOH
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMAC
DMF
CH3CN
CH2Cl2
PhCH3
DCE
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
100
100
100
100
100
100
100
100
100
100
100
100
100
90
31
44
< 5
34
35
67
0
8
< 5
9
0
59
0
56
39
65
59
51
82
81
KOt-Bu
–
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu(1equiv)
9
10
11
12
13
14
15
16
17
18
19
20
80
110
120
100
100
100
KOt-Bu(3equiv)
KOt-Bu(4equiv)
aReaction conditions: 1a (1.0 mmol), 2a (1.5 mmol), base (2 equiv), solvent (2.0 mL).
bIsolate yield.
product (Table 1, entries 18, 6). On the basis of these results, it was obvious that the optimal
conditions for the cyclization of 2-iodoaniline with dithiocarbamate were using KOt-Bu as
base and DMSO as solvent at 100°C for 4.5 h.
In order to expand the scope of the reaction, we also optimized the use of 2-halo-
anilines and specifically 2-bromoanilines with dithiocarbamates. Based on the results
obtained from the optimization for 2-iodoanilines, a number of copper catalysts were
further screened for the reaction of 2-bromoanilines (Table 2, entries 1–8). The control
experiments showed that copper is crucial and effective to catalyze this one-pot cyclization
reaction. Copper oxide was found to be the most suitable catalyst to promote the reac-
tion. 2-Aminobenzothiazole could be obtained in 81% yield while using CuO combined
with KOt-Bu (Table 2, entry 1). The blank experiment demonstrated that the reaction fur-
nished the product in poor yield when no copper was added (Table 2, entry 9). Decreasing
the reaction temperature to 80°C (entry 10) or decreasing the base loading to 2 equiv (entry
11) led to a decreasing yield.
Although 2-bromoaniline reacted with dithiocarbamate in a tandem manner to afford
the product in good yield, the protocol could not be applied to 2-chloroanilines success-
fully. The target product could only be obtained in 9% yield when CuO was used as catalyst
(Table 3, entry 1). To the best of our knowledge, very few examples were reported to pre-
pare 2-aminobenzothiazoles starting from 2-chloroanilines due to the low reactivity of the
C–Cl bond. Encouraged by the results obtained with 2-iodoaniline and 2-bromoaniline,
we began to explore the reaction between 2-chloroaniline and dithiocarbamate. As shown

4
W. XU ET AL.
Table 2. Screening reaction conditions for 2-bromoaniline and dithiocarbamate.a
NH2
N
conditions
S
N
+
N
S
Br
S
3A
2a
1e
Entry
[Cat]
Solvent
Base
Temp (°C)
Yield (%)b
1
2
3
4
5
6
7
8
9
CuO
CuI
CuBr
CuCl
Cu(OAc)2
Cu(OTf)2
CuSO4
CuCl2
–
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu
100
100
100
100
100
100
100
100
100
80
81
62
80
66
68
78
76
75
35
42
67
10
11
CuO
CuO
KOt-Bu
KOt-Bu(2equiv)
100
aReaction condition: 1e (1.0 mmol), 2a (1.2 mmol), [Cu] (8 mol%), base (3 equiv), solvent (2.0 mL) for 5 h.
bIsolated yield.
Table 3. Screening reaction conditions for 2-chloroaniline and dithiocarbamate.a
NH2
N
S
Conditions
S
N
+
N
S
Cl
3A
2a
1k
Entry
[Cat]
CuO
Pd(dba)2
PdBr2
Solvent
Base
Temp (°C)
Yield (%)b
1
2
3
4
5
6
7
8
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu
KOt-Bu
100
100
100
100
100
100
80
9
61
24
PdCl2
19
Pd(PPh3)4
Pd(OAc)2
Pd(PPh3)4
Pd(PPh3)4
86
NR
26
KOt-Bu
KOt-Bu
KOt-Bu(2equiv)
100
< 5
aReaction condition: 1k (1.0 mmol), 2a (1.2 mmol), [Pd] (5 mol%), base (3 equiv), solvent (2.0 mL) for 5 h.
bIsolated yield.
in Table 3, a number of palladium catalysts were tested for the reaction, and we found that
Pd(PPh3)4 combined with KOt-Bu provided excellent result, affording the desired prod-
uct in 86% isolated yield (Table 3, entry 5). However, other palladium catalysts such as
PdCl2, PdBr2 and Pd(dba)2 displayed inferior results in the model reaction, providing the
product in poor to moderate yields (Table 3, entries 2–4). Pd(OAc)2 almost had no catal-
ysis effect in this reaction (Table 3, entry 6). Decreasing the reaction temperature to 80°C
(entry 7) or decreasing the base loading to 2 equiv (entry 8) led to dramatically decreasing
yields.
With the optimal reaction conditions in hand, we began to scope the substrates of
2-haloanilines and dithiocarbamates. Substrates 1b and 1c, having the same functional
group (Cl) on the meta or para position of iodine, afforded the corresponding products in
93% and 81% yields, respectively (Table 4, entries 2–3). Substrate 1d, bearing a somehow

JOURNAL OF SULFUR CHEMISTRY
5
Table 4. Metal-free or transition-metal-catalyzed synthesis of substituted 2-aminobenzothiazoles.a
R
2
NH
2
KOt-Bu, Metal
S
N
R
N
S
2
R
2
R
+
1
R
N
1
S
DMSO, 100°C
R
2
X
X= I, Br, Cl
3
1
2
Entry
1
2-Halogenanilines
Dithiocarbamates
Product
Yieldb(%)
82
NH
2
N
S
S
N
N
I
S
2a
3A
1a
NH2
S
S
N
N
N
S
2
3
4
5
6
7
8
Cl
Cl
I
93
81
Cl
1b
1c
1d
2a
3B
NH
I
2
S
N
N
N
N
N
N
Cl
N
N
S
S
2a
3C
NH
I
2
S
N
N
S
S
Br
83
Br
2a
3D
NH
2
S
N
S
N
81Cat1
75Cat1
79Cat1
77Cat1
S
Br
1e
1f
2a
3A
NH
Br
2
S
N
N
S
S
Br
Br
2a
3D
NH2
Br
S
N
S
N
S
1g
1h
2a
3E
NH2
Br
S
N
S
N
S
2a
3F
(continued).

6
W. XU ET AL.
Table 4. Continued.
R
2
NH
2
KOt-Bu, Metal
S
N
R
N
S
2
R
2
R
+
1
R
N
1
S
DMSO, 100°C
R
2
X
X= I, Br, Cl
3
1
2
Entry
9
2-Halogenanilines
Dithiocarbamates
Product
Yieldb(%)
53Cat1
N
NH
Br
2
S
N
N
N
N
N
N
S
N
S
1i
1j
2a
3G
NH2
Br
S
N
S
N
10
11
12
Cl
81Cat1
86Cat2
73Cat2
S
Cl
2a
3B
NH2
Cl
S
N
S
N
S
1k
1l
2a
3A
NH
Cl
2
S
N
N
S
S
Br
Br
2a
3D
H CO
3
N
N
H3CO
NH2
Cl
S
S
N
S
13
91Cat2
1m
2b
3H
aReaction conditions: 1 (1.0 mmol), 2 (1.5 mmol), KOt-Bu (3.0 mmol), [Cat1] (CuO: 8 mmol%), [Cat2] (Pd(PPh3)4: 5 mmol%),
DMSO (3 mL) at 100°C.
bIsolated yield.
electron-withdrawing group (Br) on the meta position of iodine reacted with dithiocar-
bamate smoothly affording product 3D in 83% yield (Table 4, entry 4). Substrates 1g and
1h, attaching an electron-donating group (Me) on the para or meta position of bromine,
could cyclize well with dithiocarbamate to give the desired products in 79% and 77% yield,
respectively (Table 4, entries 7–8). It is noteworthy that the substrate 1i, a heterocycle
bromine, cyclized well with 2a to successfully give the target product 3G in moderate yield
(entry 9). To our delighted, substrate 1m reacted well with dithiocarbamate (2b) to provide
methoxy-substituted benzothiazole 3H in a remarkable 91% yield (entry 13).
A plausible mechanism for the reaction can be the following: The first step is the for-
mation of aryl thioureas promoted by base, then the subsequent transformation thereof

JOURNAL OF SULFUR CHEMISTRY
7
into aryl-isothioureas. The second step is the metal-free or transition-metal-catalyzed
intramolecular cross-coupling reaction providing 2-aminobenzothiazoles.
3. Conclusion
In conclusion, a practical and feasible protocol was developed for the synthesis of 2-
aminobenzothiazoles. In the presence of KOt-Bu, 2-haloarylamines reacted with dithiocar-
bamates to give the cyclization products smoothly. 2-Bromoaniline could be transformed
to the desired 2-aminobenzothiazoles under metal-free conditions. It is noteworthy that
in the presence of CuO and Pd(PPh3)4, less reactive 2-bromoanilines and 2-chloroanilines
could also afford the target products smoothly. The protocol showed its practical synthetic
value to prepare the molecular entities possessing potential antibacterial and antimicrobial
activity.
4. Experimental
1H NMR and 13C NMR spectra were measured using TMS as internal standard on a Bruker
400 AC NMR spectrometer. A high-resolution mass spectra (ESI–HRMS) were determined
on an Ion Spec (7.0 T) spectrometer. All starting materials were purchased from commer-
cial suppliers and used without further purification unless otherwise stated. DMSO was
dried with molecular sieves. Yields refer to isolated compounds estimated to be 95% pure
as determined by 1H NMR and capillary GC analysis.
4.1. Typical procedure for the preparation of 2-aminobenzothiazoles starting from
2-iodoanilines in the presence of KOt-Bu (TP1)
Using a dried tube, equipped with a magnetic stirrer and a septum, 2-iodoaniline (0.22 g,
1.0 mmol) was dissolved in DMSO (3 mL), and KOt-Bu (0.34 g, 3 mmol) was added. The
mixture was stirred for 5 min, then dithiocarbamate (0.296 g, 1.5 mmol) was added. The
reaction mixture was heated at 100°C and checked by TLC until the starting material was
finished. The reaction mixture was cooled down to room temperature and then quenched
with sat. NH4Cl solution (5 mL) and extracted with ethyl acetate (10 mL × 3), dried over
anhydrous Na2SO4 and concentrated under vacuum. The residue was purified by flash
column chromatography to afford the desired product (146 mg, 82%).
4.2. Typical procedure for the preparation of 2-aminobenzothiazoles starting from
2-bromoanilines in the presence of CuO and KOt-Bu (TP2)
A dried tube, equipped with a magnetic stirred and a septum, 2-bromoaniline (0.17 g,
1.0 mmol) was dissolved in DMSO (3 mL), KOt-Bu (0.34 g, 3 mmol) was added. The mix-
ture was stirred for 5 min, and then dithiocarbamate (0.296 g, 1.5 mmol) and copper oxide
(6.4 mg, 8 mmol%) were added. The reaction mixture was heated at 100°C and checked
by TLC until the starting material was finished. The reaction mixture was cooled down
to room temperature, and then quenched with sat. NH4Cl solution (5 mL) and extracted
with ethyl acetate, dried over anhydrous Na2SO4 and concentrated under vacuum. The

8
W. XU ET AL.
residue was purified by flash column chromatography to afford the desired product
(144 mg, 81%).
4.3. Typical procedure for the preparation of 2-aminobenzothiazoles starting from
2-chloroanilines in the presence of Pd(PPh3)4 and KOt-Bu (TP3)
A dried tube, equipped with a magnetic stirred and a septum, 2-chloroaniline (0.13 g,
1.0 mmol) was dissolved in DMSO (3 mL), and KOt-Bu (0.34 g, 3 mmol) was added. The
mixture was stirred for 5 min, and then dithiocarbamate (0.30 g, 1.5 mmol) and tetrak-
ispalladium (57.7 mg, 5 mmol%) were added. The reaction mixture was then heated at
100°C and checked by TLC until the starting material was finished. The reaction was
cooled down to room temperature, and then quenched with sat. NH4Cl solution (5 mL)
and extracted with ethyl acetate, dried over anhydrous Na2SO4 and concentrated under
vacuum. The residue was purified by flash column chromatography to afford the desired
product (153 mg, 86%).
4.4. Products data
4.4.1. N,N-Dimethylbenzo[d]thiazol-2-amine (3A)
Brown solid, M.P.: 83–85°C. 1H NMR (400 MHz, CDCl3) δ: 7.58 (t, J = 7.6 Hz, 2H), 7.28
(t, J = 8.0 Hz, 1H), 7.05 (t, J = 7.8 Hz, 1H), 3.21 (s, 6H). 13C NMR (100 MHz, CDCl3)
δ: 168.3, 152.7, 130.4, 125.7, 120.7, 120.4, 118.5, 39.8. HRMS (ESI) Calcd for C9H10N2S
(178.0565), found: 178.0557.
4.4.2. 6-Chloro-N,N-dimethylbenzo[d]thiazol-2-amine (3B)
1
Pale white solid. M.P.: 100–102°C. H NMR (400 MHz, CDCl3) δ: 7.51 (s, 1H), 7.43 (d,
J = 4.4 Hz, 1H), 7.21 (d, J = 4.4 Hz, 1H), 3.15 (s, 6H). 13C NMR (100 MHz, CDCl3) δ:
168.6, 151.6, 132.1, 126.4, 126.0, 120.3, 119.3, 40.4. HRMS (ESI) Calcd for C9H9ClN2S
(212.0175), found: 212.0186.
4.4.3. 5-Chloro-N,N-dimethylbenzo[d]thiazol-2-amine (3C)
1
Pale white solid. M.P.: 108–110°C. H NMR (400 MHz, CDCl3) δ: 7.46 (s, 1H), 7.39 (d,
J = 4.0 Hz, 1H), 6.93 (s, 1H), 3.12 (s, 6H). 13C NMR (100 MHz, CDCl3) δ: 169.5, 154.2,
131.9, 129.3, 121.2, 121.0, 118.7, 40.1. HRMS (ESI) Calcd for C9H9ClN2S (212.0175),
found: 212.0164.
4.4.4. 6-Bromo-N,N-dimethylbenzo[d]thiazol-2-amine (3D)
Pale brown solid. M.P.: 107.0–109°C. 1H NMR (400 MHz, CDCl3) δ: 7.66 (s, 1H), 7.42–7.34
(m, 2H), 3.19 (s, 6H). 13C NMR (100 MHz, CDCl3) δ: 168.8, 151.8, 132.5, 129.2, 123.1,
119.8, 113.3, 40.3. HRMS (ESI) Calcd for C9H9BrN2S (255.9670), found: 255.9679.
4.4.5. N,N-5-Trimethylbenzo[d]thiazol-2-amine (3E)
Pale white solid. M.P.: 115–116°C. 1H NMR (400 MHz, CDCl3) δ: 7.34 (t, J = 13.60 Hz,
2H), 6.78 (d, J = 3.8 Hz, 1H), 3.07 (s, 6H), 2.30 (s, 3H). 13C NMR (100 MHz, CDCl3) δ:
169.1, 153.3, 135.9, 127.6, 122.2, 120.2, 119.3, 39.7, 21.6. HRMS (ESI) Calcd for C10H12N2S
(192.0721), found: 192.0733.

JOURNAL OF SULFUR CHEMISTRY
9
4.4.6. N,N-6-Trimethylbenzo[d]thiazol-2-amine (3F)
Pale brown solid. M.P.: 82–84°C. 1H NMR (400 MHz, CDCl3) δ: 7.37 (d, J = 4.0 Hz, 1H),
7.28 (s, 1H), 6.99 (d, J = 3.8 Hz, 1H), 3.05 (s, 6H), 2.28 (s, 3H). 13C NMR (100 MHz,
CDCl3) δ: 168.1, 150.7, 131.1, 130.6, 127.1, 120.7, 118.3, 40.4, 20.9. HRMS (ESI) Calcd
for C10H12N2S (192.0721), found: 192.0713.
4.4.7. N,N-Dimethylthiazolo[4,5-b]pyridine-2-amine (3G)
1
Pale brown solid. M.P.: 94–96°C. H NMR (400 MHz, CDCl3) δ: 8.30 (s, 1H), 7.77 (d,
J = 4.0 Hz, 1H), 6.87–6.84 (t, J = 6.8 Hz, 1H), 3.16 (s, 6H). 13C NMR (100 MHz, CDCl3) δ:
170.0, 164.6, 146.4, 128.8, 125.3, 115.8, 40.0. HRMS (ESI) Calcd for C8H9N3S (179.0517),
found: 179.0529.
4.4.8. 5-Methoxy-N,N-diethylbenzo[d]thiazol-2-amine (3H)
1
Light yelow solid, M.P.: 77–78°C. H NMR (400 MHz, CDCl3) δ: 7.85 (s, 1H), 7.18 (d,
J = 9.2 Hz, 1H), 6.59 (d, J = 9.2 Hz, 1H), 3.74 (s, 7H), 1.28 (t, J = 7.2 Hz, 6H). 13C NMR
(100 MHz, CDCl3) δ: 179.1, 158.1, 137.1, 129.1, 117.8, 112.2, 111.3, 55.7, 45.7, 12.7. HRMS
(ESI) Calcd for C11H14ClN2S (223.0983), found: 223.0975.
Acknowledgements
We also thank Prof. Aiwen Lei at Wuhan University for his generous NMR analysis support.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
We thank the foundation support from National Natural Science Foundation of China (21302150),
Hubei Provincial Department of Education (D20131501), Scientific Research Foundation for the
Returned Overseas Chinese Scholars, State Education Ministry [2012] 1707, President foundation
of Wuhan Institute of Technology (2014038), foundation of Chutian distinguished fellow from Hubei
Provincial Department of Education, foundation of High-end Talent Cultivation Program from
Wuhan Institute of Technology.
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