Synthesis and biological activities of 2-amino-thiazole-5-carboxylic acid phenylamide derivatives

Article abstract of DOI:10.1002/ardp.201000281

In an attempt to develop potent and selective anti-tumor drugs, a series of novel 2-amino-thiazole-5-carboxylic acid phenylamide derivatives were designed based on the structure of dasatinib. All compounds were synthesized by a systematic combinatorial chemical approach. Biological evaluation revealed that N-(2-chloro-6-methylphenyl)-2-(2-(4-methylpiperazin-1-yl)acetamido) thiazole-5-carboxamide (6d) exhibited high antiproliferative potency on human K563 leukemia cells comparable to dasatinib. Against mammary and colon carcinoma cells 6d was either inactive (MDA-MB 231) or distinctly less active (MCF-7 and HT-29: IC₅₀=20.2 and 21.6μM, respectively). Dasatinib showed at each cell line IC₅₀<1μM. The results of this structure activity relationship study clearly documented that the pyrimidin-4-ylamino core of dasatinib is responsible for the anti-tumor activity against non-leukemia cell lines.

Full text of DOI:10.1002/ardp.201000281

Arch. Pharm. Chem. Life Sci. 2011, 344, 451–458
451
Full Paper
Synthesis and Biological Activities of 2-Amino-thiazole-5-
carboxylic Acid Phenylamide Derivatives
Wukun Liu1,2, Jinpei Zhou1, Fan Qi1, Kerstin Bensdorf2, Zhiyu Li1, Huibin Zhang1, Hai Qian1,
Wenlong Huang1, Xueting Cai3, Peng Cao3, Anja Wellner2, and Ronald Gust2,4
1 Department of Medicinal Chemistry, China Pharmaceutical University, Nanjing, P.R. China
2
¨
Institute of Pharmacy, Freie Universitat Berlin, Berlin, Germany
3 Laboratory of Cellular and Molecular Biology, Jiangsu Province Institute of Traditional Chinese Medicine,
Nanjing, P.R. China
4
¨
Institut fu¨r Pharmazie, Universitat Innsbruck, Innsbruck, Austria
In an attempt to develop potent and selective anti-tumor drugs, a series of novel 2-amino-thiazole-5-
carboxylic acid phenylamide derivatives were designed based on the structure of dasatinib. All
compounds were synthesized by a systematic combinatorial chemical approach. Biological
evaluation revealed that N-(2-chloro-6-methylphenyl)-2-(2-(4-methylpiperazin-1-yl)acetamido)thiazole-
5-carboxamide (6d) exhibited high antiproliferative potency on human K563 leukemia cells
comparable to dasatinib. Against mammary and colon carcinoma cells 6d was either inactive
(MDA-MB 231) or distinctly less active (MCF-7 and HT-29: IC50 ¼ 20.2 and 21.6 mM, respectively).
Dasatinib showed at each cell line IC50 < 1 mM. The results of this structure activity relationship
study clearly documented that the pyrimidin-4-ylamino core of dasatinib is responsible for the anti-
tumor activity against non-leukemia cell lines.
Keywords: Antiproliferative / Dasatinib / Protein tyrosine kinases / Synthesis
Received: September 28, 2010; Revised: December 3, 2010; Accepted: December 14, 2010
DOI 10.1002/ardp.201000281
Introduction
vation of PTKs occurs frequently in tumor tissues [5]. The
strong correlation of aberrant or over-expressed PTKs with a
number of proliferative diseases has raised the possibility
that PTK inhibitors may afford new approaches toward anti-
cancer therapeutics [6, 7].
Tyrosine kinases are a subgroup of the larger class of protein
kinases that can catalyze the transfer of g-phosphoryl groups
from ATP to tyrosine hydroxyls of proteins. Phosphorylation
of proteins by kinases is an important mechanism in signal
transduction for regulation of cellular activity [1, 2]. These
protein tyrosine kinases (PTKs) are classified as receptor PTKs
(e.g., insulin receptor and EGF receptor) and non-receptor
PTKs (e.g., BCR-ABL and SRC) [3, 4]. They play a key role in
the regulation of cell proliferation, differentiation, metab-
olism, migration, and survival. Overexpression or high acti-
The introduction of the BCR–ABL kinase inhibitor imatinib
revolutionized the treatment of chronic myeloid leukemia
(CML). However, most patients with CML receiving imatinib
still harbor molecular residual disease. Even worse, some
patients develop resistance associated with ABL kinase
domain mutations [8].
Dasatinib (Fig. 1), a potent dual inhibitor of SRC and ABL
kinase, was recently approved for the oral treatment of CML
and Philadelphia chromosome-positive acute lymphoblastic
leukemia [9–16]. This drug has a good therapeutic effect on a
wide range of tumors, especially it can inhibit HMC-1 cell
proliferation and prevent self-Kit kinase phosphorylation
[10]. In the cell test, the inhibitory effect of dasatinib on
Correspondence: Jinpei Zhou, Department of Medicinal Chemistry,
China Pharmaceutical University, Tongjia Xiang 24, 210009 Nanjing,
P.R. China.
E-mail: jpzhou668@163.com
Fax: þ86 25 83271480
Abbreviations: 5-FU, 5-fluorouracil; CML, chronic myeloid leukemia;
CYP3A4, cytochrome P450 3A4; PBS, phosphate buffered saline;
PTKs, protein tyrosine kinases.
The author contributed equally: Ronald Gust.
E-mail: ronald.gust@uibk.ac.at
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Arch. Pharm. Chem. Life Sci. 2011, 344, 451–458
decarbonylation in 73% yield under vacuum distillation.
Then, treatment of 1 with either 2-methylaniline or 2-
chloro-6-methylaniline in THF using pyridine as base
afforded the substituted (E)-N-phenyl-3-ethoxyacrylamides
2a,b in 74–78% yields. Treatment of 2a,b with N-bromosuccin-
imide (NBS) in a mixture of water and 1,4-dioxane gave the
crude a-formyl-a-bromoacetate hemiacetals 3a,b. Addition of
thiourea in situ to crude 3a,b and heating the resulting
mixture at 808C for 2 h afforded the 2-amino-thiazole-5-
carboxylic acid phenylamides 4a,b which were isolated in
about 70% yield. With an efficient method available for the
large scale synthesis of 4a,b, we next turned our attention to
the direct coupling of 4a,b with chloroacetyl chloride. Using
K2CO3 as base and slowly dropping the chloroacetyl chloride,
the coupling reaction took place in THF at 08C. The reaction
was complete after refluxing for 3 h affording the key
intermediates 5a,b in a yield of about 80%. Finally, 5a,b
reacted with secondary amines to give the desired products
6a–f, 7a–f in 58–89% yields.
Cl
N
N
N
H
N
N
N
N
H
S
O
HO
Dasatinib
Figure 1. The structure of dasatinib.
variability of BCR-ABL kinase is stronger than that of imati-
nib, and has a high degree of selectivity to normal hemato-
poietic cells and leukemia cells [11]. Preclinical data have
indicated that this drug is metabolized primarily through
cytochrome P450 3A4 (CYP3A4) [12, 13]. Currently dasatinib is
in clinical trials for the treatment of solid tumors and gastro-
intestinal stromal tumors [12, 13].
As a second-generation BCR–ABL inhibitor, dasatinib has
shown significant activity after imatinib failure in clinical
trials, but still face similar obstacles to imatinib, including
negligible activity against the frequent BCR–ABL T315I
mutation and modest effects in advanced phases of CML [8].
The three-dimensional structure of ABL kinase, SRC kinase
complexed with dasatinib showed that a pair of hydrogen
bonds was formed in the hinge region of the ATP-binding site
between the 2-amino hydrogen of dasatinib and the carbonyl
oxygen of Met318, between the 3-nitrogen of the thiazole
ring of dasatinib and the amide nitrogen of Met318. A hydro-
gen bond was also formed between the hydroxyl oxygen of
Thr315 and the amide nitrogen of dasatinib. However no
hydrogen bonds was found between the pyrimidine of dasa-
tinib and protein despite it may account for the increased
binding affinity [14–16].
Biological activity
All target compounds were first evaluated for growth inhibi-
tory activity against MCF-7 and MDA-MB 231 breast cancer
and HT-29 colon cancer cell lines according to a previous
method [19]. In addition to the target compounds 6a–f, 7a–f,
gefitinib, dasatinib as well as the established cytostatic agent
5-fluorouracil (5-FU) were used as additional references. IC50
values for the reference compounds were calculated
(OriginPro 8) and are presented in Table 1. Gefitinib was as
active as 5-FU at all cell lines, while dasatinib reduced the cell
growth more effective with IC50 < 1 mM. Out of the new
compounds only 6d and 7a were able to reduce the cell
growth (all other compounds possessed IC50 > 40 mM).
Both were active at HT-29 cells (IC50 ¼ 21.6 and 21.7 mM,
respectively) while at the MCF-7 cell line only 6d showed
an IC50 < 40 mM (20.2 mM). The excellent growth inhibitory
effects of dasatinib at the cell lines used agreed with its actual
clinical development for the treatment of solid tumors. It is
very likely that for this indication a pyrimidin-4-ylamine core
is necessary. Exchange by an acetylamide drastically reduced
the activity (compare dasatinib with 6e). Structural modifi-
cations cannot increase the growth inhibitory efficacy. For
the investigations on leukemia cells we selected compounds
with residues at the acetylamide very similar to that of dasatinib
(-(2-hydroxyethyl)piperazin-1-yl), gefitinib (-morpholino) and
imatinib (4-methylpiperazin-1-yl). Therefore, 6c, 6d, 6e, 7d,
and 7e were tested against human K563 leukemia cells by
using the MTT method [20]. Compounds 6d (16.3 mM) and 6e
(17.8 mM) showed IC50 values comparable to dasatinib
(11.08 mM) (Fig. 2). The fluorescence spectroscopic evaluation
of K563 cells indicated a decreased amount of survival cells
after incubation with compounds 6d, 6e, and dasatinib at
Encouraged by the successful development of dasatinib,
our research was focused on the synthesis of 2-amino-
thiazole-5-carboxylic acid phenylamide derivatives. In order
to investigate whether the pyrimidin-4-ylamino moiety is
critical for activity, acetyl substitution was adopted as alter-
nate scaffold at the 2-amino group. For comparison, we also
developed some derivatives with the absence of the chloro
atom at the phenyl ring moiety.
All compounds were synthesized by a systematic combina-
torial chemical approach which is recently widespread as tool
for the discovery of new therapeutic agents [17] and screened
for cytotoxic activities against different cancer cell lines.
Result and Discussion
Chemistry
The synthetic route to the target compounds was similar to
the synthesis of dasatnib and outlined in Scheme 1 [16, 18].
Thus, (E)-3-ethoxyacryloyl chloride 1 was prepared by reac-
tion of ethoxyethene and oxalyl chloride with subsequent
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Arch. Pharm. Chem. Life Sci. 2011, 344, 451–458
2-Amino-thiazole-5-carboxylic Acid Phenylamide Derivatives
453
O
R1
a
b
EtO
NH
EtO
Cl
Cl
+
Cl
O
EtO
O
O
2a,b
1
c
Br
R1
N
S
R1
H
EtO
NH
H2N
d
N
OH
O
O
4a,b
3a,b
e
O
O
N
N
R1
R1
H
H
R2
Cl
f
N
H
N
N
H
N
S
S
O
O
5a,b
6a-f, 7a-f
7a
6a
6b
R1= H,
R2 =
R1= Cl,
R2 =
N
N
N
7b
7c
R1= H, R2 =
R1= Cl, R2 =
N
N
6c
R1= H,
R2=
R1= Cl,
R2=
O
N
O
7d
7e
6d
6e
R1= H,
R1= H,
R1= Cl,
R1= Cl,
R2 =
R2 =
R2 =
R2 =
N
N
N
N
N
N
N
N
OH
OH
7f
6f
R2 =
R1= H,
R1= Cl, R2 =
N
N
Reagents and conditions: (a) 0°C; (b) substituted aniline, pyridine, THF, 0–5°C; (c) N-bromosuccinimide, 1,4-dioxane,
water, –10–0°C; (d) H2NCSNH2, 80°C; (e) K2CO3 chloroacetyl chloride THF, 0°C; (f) K2CO
3 , KI, secondary amine, THF, 60°C
Scheme 1. Synthetic route of compounds 6a–f, 7a–f.
Table 1. Antiproliferative effects against MCF-7 and MDA-MB 231
human breast cancer and HT-29 colon cancer cell lines.
10 mM for 72 h (Fig. 3). Interestingly, the methylphenyl sim-
ilarities 7d and 7e showed less activity with IC50 values
beyond 40 mM. The morpholino derivative 6c exhibited
moderate inhibition activities with an IC50 value of
27.2 mM. These results indicated that compounds 6d and
6e possess high selectivity for leukemia cells and cytotoxic
properties comparable to dasatinib.
Compound
Cytotoxicity IC50, [mM]a,b
MDA-MB 231
MCF-7
HT-29
6d
7a
Gefitinib
Dasatinib
5-FU
>40
>40
20.2 ꢀ 4.7
>40
21.6 ꢀ 0.6
21.7 ꢀ 0.6
12.1 ꢀ 0.1
<1
7.3 ꢀ 0.1
2.3 ꢀ 0.7
<1
9.6 ꢀ 0.3
<1
4.7 ꢀ 0.4
7.3 ꢀ 1.0
Conclusion
a The IC50 values represent the concentration which results in a
50% decrease in cell growth after 72 h incubation. b Values are
the means of at least 3 experiments.
A series of novel 2-amino-thiazole-5-carboxylic acid phenyl-
amide derivatives were synthesized and their biological
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454
W. Liu et al.
Arch. Pharm. Chem. Life Sci. 2011, 344, 451–458
relationship are in progress and will give us the opportunity
to explain the tumor selectivity more precisely.
Experimental
Chemistry
General
All reagents were purchased from Shanghai Chemical Reagent
Company. Dasatinib and gefitinib were synthesized according to
previous methods [16, 18, 21]. Column chromatography: Silica
gel 60 (200–300 mesh). Thin-layer chromatography: Silica gel 60
F254 plates (250 mm; Qingdao Ocean Chemical Company,
China). Melting point: Capillary tube; uncorrected. IR spectra:
Shimadzu FTIR-8400S spectrophotometer. NMR spectra: Bruker
ACF-300 Q apparatus at 300 MHz for 1H-NMR and Bruker ADX
400 spectrometer at 100 MHz for 13C-NMR (internal standard,
TMS). Mass spectrometry: Hewlett–Packard 1100 LC/MSD spec-
trometer; in m/z. Elemental analyses: CHN-O-Rapid instrument.
(E)-3-Ethoxyacryloyl chloride 1 [22]
Ethoxyethene (30 mL, 313 mmol) was slowly added to oxalyl
chloride (36.8 mL, 427 mmol) at 08C. The reaction mixture
was maintained for 2 h at 08C and was then allowed to warm
to room temperature for 12 h. Excess of oxalyl chloride was
distilled off, and the residue was heated at 1208C for 30 min
and then purified by vacuum distillation, affording 1 (30.7 g,
73.0%) as a colorless oil. Bp: 77–798C, 12 Torr.
(E)-N-(2-Chloro-6-methylphenyl)-3-ethoxyacrylamide 2a
To a cold stirring solution of 2-chloro-6-methylaniline (11.9 g,
840 mmol) and pyridine (10.0 g, 1260 mmol) in THF (60 mL), 1
(16.8 g, 1260 mmol) was added slowly keeping the temperature
at 0–58C. The mixture was then warmed and stirred 3 h at room
temperature. Hydrochloric acid (1 N) was added at 0–108C to
adjust a pH of 5. The mixture was diluted with water (62 mL) and
the resulting solution was concentrated under vacuum to the
thick slurry. The slurry was diluted with toluene (55.0 mL) and
stirred for 15 min at 20–228C then 1 h at 08C. The solid was
collected by vacuum filtration, washed with water (2 ꢁ 20 mL)
and dried to give 2a (15.76 g, 78.3% yield). Mp: 98–1038C; 1H-NMR
Figure 2. Dose dependent antiproliferative effects and IC50 values
of compounds and dasatinib on human K563 leukemia cellsa, b, c)
a)
The IC50 values represent the concentration which results in a
50% decrease in cell growth after 72 h incubation. b) Values are the
means of at least 3 experiments. c) In some cases the error bars are
hidden behind the symbols.
–
(d -DMSO) d: 9.27 (1H, s, NH). 7.44 (1H, d, J ¼ 12.3 Hz, –CH ),
–
6
7.27–7.36 (1H, d, J ¼ 7.5 Hz, Ar-H), 7.10–7.26 (2H, m, Ar-H), 5.58
–
(1H, d, J ¼ 12.3 Hz, –CH ), 3.93 (2H, q, J ¼ 6.9 Hz, –CH ), 2.15
–
2
(3H, s, –CH3), 1.27 (3H, t, J ¼ 6.9 Hz, –CH3); ESI-MS: [M þ H]þ 240.
(E)-N-(2-Methylphenyl)-3-ethoxyacrylamide 2b
Compound 2b was synthesized from 2-methylaniline (11.9 g,
840 mmol), pyridine (10.0 g, 1260 mmol) in THF (60 mL), and
1 (16.8 g, 1260 mmol) according to the procedure used to syn-
thesize 2a in 74.0% yield (12.7 g); Mp: 92–968C; ESI-MS: [M þ H]þ
206.
activities were evaluated. N-(2-Chloro-6-methylphenyl)-2-(2-(4-
methylpiperazin-1-yl)acetamido)thiazole-5-carboxamide (6d)
exhibited good antiproliferative effects on human K563 leu-
kemia cells. The results of this study documented that the
pyrimidin-4-ylamino core seems to be responsible for the
high activity of dasatinib against solid tumors. Exchange
by an acetamide scaffold terminated nearly completely the
effects at MCF-7, MDA-MB 231, and HT-29 cell lines but pre-
vent the activity against leukemia cells (K565). In the next
step of our investigations we will focus our attention on the
mode of action. Investigations to get insight into the enzyme
inhibitory properties as well as an enlarged structure activity
2-Amino-N-(2-chloro-6-methylphenyl)thiazole-5-
carboxamide 4a
To a mixture of 2a (3.00 g, 12.50 mmol) in 1,4-dioxane (23 mL)
and water (23 mL) N-bromosuccinimide (3.90 g, 21.90 mmol) was
added at ꢂ10 to 08C. The slurry was warmed and stirred at 20–
228C for 3 h. Thiourea (1.50 g, 19.70 mmol) was added and the
mixture heated to 808C. After 2 h, the resulting solution was
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Arch. Pharm. Chem. Life Sci. 2011, 344, 451–458
2-Amino-thiazole-5-carboxylic Acid Phenylamide Derivatives
455
Figure 3. Survival cells after incubation compounds at 10 mM for 72 h. (Control: above left; dasatinib: right above; 6d: below left;
6e: below right.)
–
NH), 9.93 (1H, s, NH), 8.30 (1H, s, N–CH C–), 7.32–7.15 (3H, m,
–
–
cooled to 20–228C and conc. ammonium hydroxide (2.85 mL)
was added dropwise. The resulting slurry was concentrated
under vacuum to about half volume and cooled to 0–58C. The
solid was collected by vacuum filtration, washed with cold water
(10 mL) and dried to give 4a (2.4 g, 71.9% yield). Mp: 258–2628C;
1H-NMR (d6-DMSO) d: 9.48 (1H, s, NH), 7.64 (2H, s, NH2), 7.57–7.51
–
Ar-H), 4.44 (2H, s, CH2), 2.23 (3H, s, CH3). ESI-MS: [M þ H]þ 345.
N-(2-Chloro-6-methylphenyl)-2-(2-chloroacetamido)-
thiazole-5-carboxamide 5b
Compound 5b was synthesized from 4b (0.81 g, 3.48 mmol)
and K2CO3 (0.83 g, 6.00 mmol) in THF (10 mL), chloroacetyl
chloride (0.68 g, 6.00 mmol) according to the procedure used
to synthesize 5a in 88.1% yield (0.94 g); Mp: 200–2048C; ESI-MS:
[M þ H]þ 310.
–
–
(1H, m, N–CH C–), 7.29–7.15 (3H, m, Ar-H), 2.20 (3H, s, CH );
3
–
–
ESI-MS: [M þ H]þ 268.
2-Amino-N-(2-methylphenyl)thiazole-5-carboxamide 4b
Compound 4b was synthesized from 2a (2.56 g, 12.50 mmol) in
1,4-dioxane (23 mL) and water (23 mL), N-bromosuccinimide
(3.90 g, 21.90 mmol), and then added thiourea (1.50 g,
19.70 mmol) and ammonium hydroxide (2.85 mL) according
to the procedure used to synthesize 4a in 70.4% yield (2.05 g);
Mp: 226–2308C; ESI-MS: [M þ H]þ 234.
General procedures for the synthesis of the target
compounds 6a–f, 7a–f
K2CO3 (0.138 g, 0.10 mmol) and KI (0.016 g, 0.01mmol) were
added to a mixture of 5a or 5b (0.60 mmol) and the respective
secondary amine (0.69 mmol) in THF (10 mL). The mixture was
then warmed at 608C for 1 h and filtered. The organic layer was
dried over Na2SO4 and the solvent was distilled off to give the
crude product, which was then purified by flash column chroma-
tography with mixture eluent of CH2Cl2 and CH3OH to give the
corresponding product.
N-(2-Chloro-6-methylphenyl)-2-(2-chloroacetamido)-
thiazole-5-carboxamide 5a
To a stirring solution of 4a (0.93 g, 3.48 mmol) and K2CO3 (0.83 g,
6.00 mmol) in THF (10 mL) chloroacetyl chloride (0.68 g,
6.00 mmol) was added slowly with cooling to keep the tempera-
ture at 08C. The reaction mixture was maintained for 5 min at
08C and then warmed at 608C for 3 h followed by cooling to room
temperature. Water (50 mL) was added slowly and the mixture
was stirred for 0.5 h at 0–58C. The solid was collected by vacuum
filtration, washed with water (15 mL) and dried to give 5a (1.00 g,
80.6% yield). Mp: 210–2128C; 1H-NMR (d6-DMSO) d: 12.78 (1H, s,
N-(2-Chloro-6-methylphenyl)-2-(2-(pyrrolidin-1-yl)-
acetamido)thiazole-5-carboxamide 6a
Column chromatography: CH2Cl2/CH3OH (20:1), (Rf ¼ 0.4); Yield,
81.5%; Mp: 220–2228C; IR (KBr, cmꢂ1): 3231, 2963, 2809,
1699, 1639, 1521, 1288, 1181, 776, 639; 1H-NMR (CDCl3) d:
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W. Liu et al.
Arch. Pharm. Chem. Life Sci. 2011, 344, 451–458
–
–
–
8.10 (1H, s, N–CH C–), 7.42 (1H, s, –NH–CO–), 7.29 (1H, d,
–
2-(2-(Azepan-1-yl)acetamido)-N-(2-chloro-6-methylphenyl)-
thiazole-5-carboxamide 6f
Column chromatography: CH2Cl2/CH3OH (20:1), Rf ¼ 0.4; Yield:
65.4%; Mp: 208–2108C; IR (KBr, cmꢂ1): 3419, 3246, 2927, 2819,
1687, 1647, 1505, 1290, 1194, 755; 1H-NMR (CDCl3) d: 8.09
J ¼ 6.0 Hz, Ar-H), 7.19 (2H, s, Ar-H), 3.44 (2H, s, –CH2–CO–),
13
2.73 (4H, br, –CH2–N–), 2.33 (3H, s, –CH3), 1.88 (4H, br, –CH2–);
–
–
–
C-NMR (CDCl ) d: 169.6 (C O, acetamido), 162.2 (S–C N,
–
–
thiazole), 160.2 (C O, carboxamide), 145.1, 142.9, 139.8, 136.4,
3
–
–
–
130.0, 129.4, 122.3 (–C ), 58.4 (CH , acetamido), 54.7 (N–CH ,
2
2
–
–
(1H, s, N–CH C–), 7.31 (1H, m, Ar-H), 7.17 (2H, m, Ar-H), 3.43
–
–
pyrrolidin), 24.1 (–CH2, pyrrolidin), 19.11 (CH3); ESI-MS: [M þ H]þ
379. Anal. calcd. for C17H19ClN4O2S: C, 53.89; H, 5.05; N, 14.79%;
Found C, 53.47; H, 5.42; N, 14.48%.
(2H, s, –CH2–CO–), 2.82 (4H, m, –CH2–N–), 2.34 (3H, s, –CH3), 1.69
(8H, br, –CH2–); ESI-MS: [M þ H]þ 407. Anal. calcd. for
C19H23ClN4O2S ꢃ 2 H2O: C, 51.52; H, 6.14; N, 12.65%; Found C,
51.93; H, 6.05; N, 12.65%.
N-(2-Chloro-6-methylphenyl)-2-(2-(piperidin-1-yl)-
acetamido)thiazole-5-carboxamide 6b
Column chromatography: CH2Cl2/CH3OH (20:1), (Rf ¼ 0.4); Yield,
88.7%; Mp: 246–2488C; IR (KBr, cmꢂ1): 3236, 2931, 2809,
1687, 1506, 1293–1220, 1178, 994, 815; 1H-NMR (CDCl3) d: 8.01
N-(2-Methylphenyl)-2-(2-(pyrrolidin-1-yl)acetamido)-
thiazole-5-carboxamide 7a
Column chromatography: CH2Cl2/CH3OH (20:1), Rf ¼ 0.45; Yield:
86.6%; Mp: 198–1998C; IR (KBr, cmꢂ1): 3469, 3265, 2799, 1689,
1630, 1507, 1476, 1289, 1155, 751; 1H-NMR (CDCl3) d: 8.01
–
–
(1H, s, N–CH C–), 7.23 (1H, d, J ¼ 3.9 Hz, Ar-H), 7.13 (2H, s,
–
–
Ar-H), 3.16 (2H, s, –CH2–CO–), 2.49 (4H, s, –CH2–N–), 2.27 (3H, s,
–CH3), 1.59 (4H, br, –CH2–), 1.43 (2H, br, –CH2–); ESI-MS: [M þ H]þ
393. Anal. calcd. for C18H21ClN4O2S: C, 55.02; H, 5.39; N, 14.26%;
Found C, 54.66; H, 5.71; N, 14.11%.
–
–
(1H, s,
N–CH C–), 7.82 (1H, d, J ¼ 7.5 Hz, Ar-H), 7.43
–
–
(1H, s, Ar-H), 7.23 (1H, d, JA ¼ JB ¼ 7.5 Hz, Ar-H), 7.15
(1H, d, JA ¼ JB ¼ 7.5 Hz, Ar-H), 3.43 (2H, s, –CH2–CO–), 2.71
(4H, br, –CH2–N–), 2.33 (3H, s, –CH3), 1.87 (4H, br, –CH2–); 13C-
–
–
NMR (CDCl ) d: 169.8 (C O, acetamido), 160.0 (S–C N, thiazole),
–
–
–
159.3 (C O, carboxamide), 140.7, 135.1, 130.6, 127.6, 126.9,
3
N-(2-Chloro-6-methylphenyl)-2-(2-morpholinoacetamido)-
thiazole-5-carboxamide 6c
Column chromatography: CH2Cl2/CH3OH (20:1), Rf ¼ 0.4; Yield,
84.2%; Mp: 224–2268C; IR (KBr, cmꢂ1): 3467, 3254, 2855,
1697, 1641, 1520, 1445, 1292, 1186, 869; 1H-NMR (CDCl3) d:
–
–
125.8, 123.7 (–C ), 58.4 (CH , acetamido), 54.7 (N–CH , pyrroli-
–
2
2
din), 24.1 (–CH2, pyrrolidin), 17.8 (CH3); ESI-MS: [M þ H]þ 345.
Anal. calcd. for C17H20N4O2S ꢃ CH2Cl2: C, 50.35; H, 5.16; N,
13.05%; Found C, 50.54; H, 5.02; N, 13.08%.
–
–
8.09 (1H, s, N–CH C–), 7.30 (1H, s, Ar-H), 7.24 (1H, s, Ar-H),
–
–
7.21 (1H, s, Ar-H), 3.83 (4H, m, –CH2–O–), 3.36 (2H, s,
N-(2-Methylphenyl)-2-(2-(piperidin-1-yl)acetamido)-
thiazole-5-carboxamide 7b
Column chromatography: CH2Cl2/CH3OH (20:1), Rf ¼ 0.45; Yield:
75.1%; Mp: 179–1808C; IR (KBr, cmꢂ1): 3451, 3266, 2932, 2853,
1692, 1635, 1447, 1292, 1196, 751; 1H-NMR (CDCl3) d: 8.03
–CH2–CO–), 2.70 (4H, br, –CH2–N–), 2.34 (3H, s, –CH3); 13C-NMR
–
–
–
(CDCl ) d: 168.5 (C O, acetamido), 162.2 (S–C N, thiazole), 160.0
–
3
–
(C O, carboxamide), 141.1, 138.2, 132.0, 131.4, 129.4, 128.2,
–
–
–
127.1 (–C ), 66.8 (O–CH , morpholino), 61.3 (–CH , acetamido),
2
2
53.9 (N–CH2, morpholino), 19.0 (CH3); ESI-MS: [M þ H]þ 395.
Anal. calcd. for C17H19ClN4O3S: C, 51.71; H, 4.85; N, 14.19%;
Found C, 51.59; H, 5.21; N, 14.42%.
–
–
(1H, s,
N–CH C–), 7.82 (1H, d, J ¼ 7.5 Hz, Ar-H), 7.43
–
–
(1H, s, Ar-H), 7.22 (1H, m, Ar-H), 7.15 (1H, d, J ¼ 7.5 Hz, Ar-H),
3.25 (2H, s, –CH2–CO–), 2.58 (4H, br, –CH2–N–), 3.34 (3H, s, –CH3),
1.66 (4H, m, –CH2–), 1.50 (2H, br, –CH2–); 13C-NMR (CDCl3) d: 169.5
N-(2-Chloro-6-methylphenyl)-2-(2-(4-methylpiperazin-
1-yl)acetamido)thiazole-5-carboxamide 6d
–
–
–
(C O, acetamido), 160.0 (S–C N, thiazole), 159.5 (C O, carbox-
–
–
–
–
amide), 149.7, 135.1, 130.6, 127.7, 126.8, 125.9, 124.2, 124.1(–C ),
–
61.6 (CH2, acetamido), 55.0 (N–CH2, piperidin), 25.9 (–CH2, piper-
idin), 23.4 (–CH2, piperidin), 17.8 (CH3); ESI-MS: [M þH]þ 359.
Anal. calcd. for C18H22N4O2S: C, 60.31; H, 6.19; N, 15.63%; Found
C, 60.69; H, 6.07; N, 15.50%.
Column chromatography: CH2Cl2/CH3OH (20:1), Rf ¼ 0.35; Yield,
80.5%; Mp: 120–1228C; IR (KBr, cmꢂ1): 3476, 3417, 3233, 2937,
2814, 1633, 1500, 1414, 1289, 779; 1H-NMR (CDCl3) d: 8.15 (1H, s,
–
–
N–CH C–), 7.29 (2H, s, Ar-H), 7.20 (1H, s, Ar-H), 3.43 (2H, s,
–
–
–CH2–CO–), 2.69 (8H, br, –CH2–N–), 2.40 (3H, s, –CH3), 2.33
(3H, s, –CH3); ESI-MS: [M þ H]þ 408, [M – H]ꢂ 406. Anal. calcd.
for C18H22ClN5O2S: C, 53.00; H, 5.44; N, 17.17%; Found C, 53.23;
H, 5.01; N, 17.55%.
N-(2-Methylphenyl)-2-(2-morpholinoacetamido)thiazole-5-
carboxamide 7c
Column chromatography: CH2Cl2/CH3OH (20:1), Rf ¼ 0.4; Yield:
81.3%; Mp: 209–2108C; IR (KBr, cmꢂ1): 3275, 2925, 2856, 1694,
1492, 1291, 1199, 1022, 869, 747; 1H-NMR (CDCl3) d: 10.43 (1H, br,
N-(2-Chloro-6-methylphenyl)-2-(2-(4-(2-hydroxyethyl)-
–
–
–NH–CO–), 8.00 (1H, s, N–CH C–), 7.81 (1H, d, J ¼ 7.2 Hz, Ar-H),
piperazin-1-yl)acetamido)thiazole-5-carboxamide 6e
Column chromatography: CH2Cl2/CH3OH (20:1), Rf ¼ 0.2; Yield:
85.7%; Mp: 220–2238C; IR (KBr, cmꢂ1): 3435, 2922, 2750, 1658,
1575, 1533, 1400, 1302, 1196, 766; 1H-NMR (CD3OD) d: 8.13 (1H, s,
–
–
7.42 (1H, s, Ar-H), 7.35 (1H, m, Ar-H), 7.14 (1H, d, J ¼ 7.2 Hz, Ar-H),
13
3.80 (4H, t, J ¼ 4.5 Hz, –CH2–O–), 3.32 (2H, s, –CH2–CO–), 2.67 (4H,
–
br, –CH2–N–), 2.33 (3H, s, –CH3); C-NMR (CDCl ) d: 168.7 (C O,
–
–
acetamido), 159.5 (S–C N, thiazole), 158.9 (C O, carboxamide),
3
–
–
–
–
–
140.3, 134.9, 130.4, 127.7, 126.8, 125.7 (–C ), 66.5 (O–CH , mor-
N–CH C–), 7.25 (1H, m, Ar-H), 7.14 (2H, d, J ¼ 6.6 Hz, Ar-H), 3.61
–
–
–
–
(2H, t, J ¼ 10.8 Hz, –CH2–O–), 3.28 (2H, s, –CH2–CO–), 3.21 (2H, t,
J ¼ 10.8 Hz, –CH2–N–), 2.49–2.63 (8H, m, –CH2–N–, piperazin),
2.21 (3H, s, –CH3); ESI-MS: [M]þ 437. Anal. calcd. for
C19H24ClN5O3S: C, 52.11; H, 5.52; N, 15.99%; Found C, 51.89;
H, 5.42; N, 16.32%.
2
pholino), 61.1 (–CH2, acetamido), 53.7 (N–CH2, morpholino), 17.6
(CH3); ESI-MS: [M þ H]þ 361, [M þ Na]þ 383, [M – H]– 359. Anal.
calcd. for C17H20N4O3S ꢃ 0.6 CH2Cl2: C, 51.38; H, 5.19; N, 13.62%;
Found C, 51.55; H, 5.35; N, 13.60%.
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Arch. Pharm. Chem. Life Sci. 2011, 344, 451–458
2-Amino-thiazole-5-carboxylic Acid Phenylamide Derivatives
457
cell biomass was determined by a crystal violet staining, followed
by extracting of the bound dye with ethanol and a photometric
measurement at 590 nm. Mean values were calculated and the
effects of the compounds were expressed as %Treated/Controlcorr
values according to the following equations:
N-(2-Methylphenyl)-2-(2-(4-methylpiperazin-1-yl)-
acetamido)thiazole-5-carboxamide 7d
Column chromatography: CH2Cl2/CH3OH (20:1), Rf ¼ 0.35; Yield:
86.5%; Mp: 198–1998C; IR (KBr, cmꢂ1): 3489, 2941, 1645,
1529, 1485, 1296, 1209, 1161, 834, 749; 1H-NMR (CDCl3) d:
–
–
8.01(1H, s, N–CH C–), 7.82 (1H, d, J ¼ 8.1 Hz, ArH), 7.38
–
–
TꢂC0
T
(1H, s, Ar-H), 7.22 (1H, s, Ar-H), 7.14 (1H, m, Ar-H), 3.28
(2H, s, –CH2–CO–), 2.67 (4H, br, –CH2–N–), 2.53 (4H, br,
–CH2–N–), 2.30 (3H, s, –CH3), 2.28 (3H, s, –CH3); ESI-MS:
[M þ H]þ 374, [M – H]– 372. Anal. calcd. for C18H23N5O2S: C,
57.89; H, 6.21; N, 18.75%; Found C, 57.98; H, 6.03; N, 18.39%.
½%ꢄ ¼
ꢁ 100
=
Ccorr
CꢂC0
where C0, control cells at the time of compound addition; C,
control cells at the time of test end; T, probes/samples at the time
of test end.
The IC50 value was determined as the concentration causing
50% inhibition of cell proliferation and calculated as mean of at
least three independent experiments (OriginPro 8).
N-(2-Methylphenyl)-2-(2-(4-(2-hydroxyethyl)piperazin-1-yl)-
acetamido)thiazole-5-carboxamide 7e
Column chromatography: CH2Cl2/CH3OH (20:1), Rf ¼ 0.3; Yield:
85.7%; Mp: 220–2238C; IR (KBr, cmꢂ1): 3435, 2922, 2750, 1658,
1575, 1533, 1400, 1302, 1196, 766; 1H-NMR (CD3OD) d: 8.21
K-563 cells viability assay
K-563 cells were obtained from Shanghai Institute of Cell Biology
(China). The cells were grown in RPMI 1640 (Life Technologies,
Inc., USA) supplemented with 10% fetal bovine serum (FBS, Life
Technologies, Inc., USA) and cultured at 378C in a humidified
atmosphere of 95% air and 5% CO2.
–
–
(1H, s, N–CH C–), 7.29 (2H, d, J ¼ 3.9 Hz, Ar-H), 7.23 (2H, m,
–
–
Ar-H), 3.82 (2H, t, J ¼ 10.8 Hz, –CH2–O–), 3.47 (2H, s, –CH2–CO–),
3.08 (4H, br, –CH2–N–), 2.96 (2H, t, J ¼ 10.8 Hz, –CH2–N–), 2.85
(4H, m, –CH2–N–), 2.31 (3H, s, –CH3); ESI-MS: [M þ H]þ 404,
[M – H]– 402. Anal. calcd. for C19H25N5O3S: C, 56.56; H, 6.25; N,
17.36%; Found C, 56.18; H, 6.44; N, 17.36%.
The experiments were performed according to established
procedures with some modifications [20]. K-563 cells were cul-
tured in medium till mid-log phase, then seeded in 96-well plate
at a density of 1 ꢁ 104 cells per well in 100 mL medium. After
24 h of incubation, K-563 cells were treated with various con-
centrations of the test compounds for 72 h. After treatment,
10 mL of 5 mg/mL MTT were added and the cells were incubated
for further 4 h at 378C. The supernatant was discarded and
100 mL of DMSO was added to each well. The mixture was shaken
on a mini shaker at room temperature for 10 min and the
spectrophotometric absorbance was measured by Multiskan
Spectrum Microplate Reader (Thermo) at 570 and 630 nm
(absorbance 570 nm, reference 630 nm). Triplicate experiments
were performed in a parallel manner for each concentration
point and the results were presented as mean ꢀ SD. The net
A570 nm – A630 nm was taken as the index of cell viability. The
net absorbance from the wells of cells cultured with 0.1% DMSO
was taken as the 100% viability value. The percent inhibition of
the treated cells was calculated by the following formula:
2-(2-(Azepan-1-yl)acetamido)-N-(2-methylphenyl)-
thiazole-5-carboxamide 7f
Column chromatography: CH2Cl2/CH3OH (20:1), Rf ¼ 0.35; Yield:
57.7%; Mp: 120–1228C; IR (KBr, cmꢂ1): 3267, 2924, 2856,
1693, 1637, 1489, 1291, 1193, 1090, 749; 1H-NMR (CDCl3) d:
–
–
8.01 (1H, s, N–CH C–), 7.82 (1H, d, J ¼ 7.5 Hz, Ar-H), 7.41
–
–
(1H, s, Ar-H), 7.22 (1H, s, Ar-H), 7.13 (1H, t, J ¼ 14.4 Hz, Ar-H),
3.41 (2H, s, –CH2–CO–), 2.80 (4H, m, –CH2–N–), 2.33 (3H, s, –CH3),
–
1.69 (8H, br, –CH2–); 13C-NMR (CDCl ) d: 169.6 (C O, acetamido),
–
163.2 (S–C N, thiazole), 160.1 (C O, carboxamide), 140.7, 135.2,
3
–
–
–
–
132.9, 130.6, 126.9, 122.4 (–C ), 58.9 (CH , acetamido), 56.5
–
–
2
(N–CH2, azepan), 27.8 (–CH2, azepan), 26.8 (–CH2, azepan),
17.8 (CH3); ESI-MS: [M þ H]þ 373. Anal. calcd. for
C19H24N4O2S ꢃ CH3OH: C, 59.38; H, 6.98; N, 13.85%; Found C,
59.74; H, 6.56; N, 13.42%.
Biological Activity
Cell Culture
½ðA570 nmꢂ A630 nm
Þ
control ꢂ ðA570 nm ꢂ A630 nm
Þtreatedꢄ
% Inhibition ¼
ðA570 nm ꢂ A630 nmÞcontrol
The human MCF-7, MDA-MB 231 breast cancer, and HT-29 colon
cancer cell lines were obtained from the American Type Culture
Collection. All cell lines were maintained as a monolayer culture
in L-glutamine containing Dulbecco’s modified Eagle’s medium
(DMEM) with 4.5 g/L glucose (PAA Laboratories, Austria), supple-
mented with 5% fetal bovine serum (FBS; Biochrom, Germany) in
a humidified atmosphere (5% CO2) at 378C.
ꢁ 100%:
The IC50 value was determined as the concentration causing 50%
inhibition of cell proliferation and calculated as mean of at least
three independent experiments (OriginPro 8).
The authors are grateful for the financial supports of National Natural
Science Foundation of China (No. 30973638). The China scholarship council
and the Deutsche Forschungsgemeinschaft (FOR 630) are gratefully
acknowledged.
Growth Inhibitory Effects
The experiments were performed according to established pro-
cedures with some modifications [19]. In 96-well plates 100 mL of
a cell suspension in culture medium (7500 cells/mL (MCF-7 and
MDA-MB 231) or 3000 cells/mL (HT-29)) were plated into each well
and were incubated for three days under culture conditions.
After the addition of various concentrations of the test com-
pounds, cells were incubated for up to 144 h. Then the medium
was removed, the cells were fixed with glutardialdehyde solution
(1%) and stored under phosphate buffered saline (PBS) at 48C. The
The authors have declared no conflict of interest.
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ß 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com