Design and synthesis of 2-iminothiazolidin-4-one moiety-containing compounds as potent antiproliferative agents

Article abstract of DOI:10.1002/ardp.201100064

A new series of 2,5-diaryliminothiazolidin-4-ones were designed and synthesized as potent antiproliferative agents. The antiproliferative activities of the 25 target compounds were evaluated against three cancer cell lines (A549, H460 and HT29) by MTT assay. Pharmacological data indicated that most of the compounds possessed moderate activity, some showed remarkable activity against one or more cell lines. As the most promising compound, 8s (with IC ₅₀ values of 1.1, 0.01 and 1.3μM against the A549, H460 and HT29 cell lines) was 1.1- to 270-fold more potent than the reference drug sorafenib. Furthermore, preliminary structure-activity relationships (SARs) were summarized to provide guidance for further design and discovery of 2-iminothiazolidin-4- one-based antiproliferative agents. A new series of 2,5-diaryliminothiazolidin- 4-ones were designed and synthesized as potent antiproliferative agents. The antiproliferative activities of the 25 target compounds were evaluated against three cancer cell lines (A549, H460 and HT29) by MTT assay. The most promising compound, 8s, was 1.1-270-fold more potent than the reference drug sorafenib. Preliminary structure-activity relationship data provide guidance for further design and discovery of 2-iminothiazolidin-4-one-based antiproliferative agents. Copyright

Full text of DOI:10.1002/ardp.201100064

Arch. Pharm. Chem. Life Sci. 2012, 000, 1–8
1
Full Paper
Design and Synthesis of 2-Iminothiazolidin-4-one Moiety-
Containing Compounds as Potent Antiproliferative Agents
Xin Zhai1, Wei Li1, Dong Chen2, Ruiwei Lai1, Jun Liu1, and Ping Gong1
1 Key Laboratory of Original New Drugs Design and Discovery of Ministry of Education, School of
Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang, China
2 Qilu Pharmaceutical Research Institute, Qilu Pharmaceutical Co., Ltd., Ji’nan, China
A new series of 2,5-diaryliminothiazolidin-4-ones were designed and synthesized as potent
antiproliferative agents. The antiproliferative activities of the 25 target compounds were
evaluated against three cancer cell lines (A549, H460 and HT29) by MTT assay. Pharmacological
data indicated that most of the compounds possessed moderate activity, some showed remarkable
activity against one or more cell lines. As the most promising compound, 8s (with IC50 values of 1.1,
0.01 and 1.3 mM against the A549, H460 and HT29 cell lines) was 1.1- to 270-fold more potent than the
reference drug sorafenib. Furthermore, preliminary structure–activity relationships (SARs) were
summarized to provide guidance for further design and discovery of 2-iminothiazolidin-4-one-
based antiproliferative agents.
Keywords: 2-Iminothiazolidin-4-one moiety / Antiproliferative evaluation / Design / Synthesis
Received: February 21, 2011; Revised: October 15, 2011; Accepted: October 21, 2011
DOI 10.1002/ardp.201100064
Introduction
zolidin-4-one derivatives [4]. Special structural character-
istics, hydrogen bond accepting ability and inherent
hydrophobic nature make 2-iminothiazolidin-4-one moiety
a versatile scaffold in drug discovery. Considerable studies
revealed that structures based on 2-iminothiazolidin-4-one-
containing moiety have been endowed with antiprolifera-
tive, antimicrobial, and anti-inflammatory activity [4, 5].
Interestingly, darbufelone, a non-steroidal anti-inflamma-
tory drug (NSAID), was reported with encouraging activity
inducing growth inhibition of lung cancer cells both in vitro
and in vivo [6].
The leading cause of death remains mainly cardiovascular
disease and cancer worldwide, while a recent report disclosed
that cancer mortality presented an increasing tendency
despite the great success of many chemotherapeutics [1].
Therefore it is urgent to develop novel antiproliferative
agents with high efficiency and low toxicity.
Drug discovery paradigm suggested that hybridizing
privileged scaffolds or merging different pharmacophore
fragments into one single structure could lead to innovative
chemicals bearing interesting biological activity. 2-Imino-
thiazolidin-4-one derivative, a special derivative of 4-thiazo-
lidinone, has been proved to be intermediate between amino
and imino tautomeric forms [2, 3]; furthermore, a pharma-
cophore derived from active molecules suggested that two
hydrogen bond acceptors and three hydrophobic regions
were common features of 5-benzylidene-2-(phenylimino)thia-
Sorafenib,
a synthetic compound targeting multiple
kinases of tumor proliferation and angiogenesis [7–8], was
approved by the FDA for the treatment of primary renal
cell carcinoma and advanced primary hepatocellular
carcinoma. In addition, it could induce complete tumor
stasis in human colon tumor xenograft model (HT-29) at
doses of 30 mg per kg and inhibited the growth of NSCLC
xenograft model (A549) [9]. Currently, efforts for developing
potent analogs of sorafenib have been the focus of many
studies [10–15]. In most modification researches including
our previous work [13], it was found that derivatives bearing
a diaryl urea framework constituted various compounds
with superior antitumor activity. Recent researches
focusing on optimizations of the diaryl urea framework of
Correspondence: Ping Gong, Key Laboratory of Original New Drugs
Design and Discovery of Ministry of Education, School of Pharmaceutical
Engineering, Shenyang Pharmaceutical University, 103 Wenhua Road,
Shenhe District, 110016 Shenyang, Liaoning, P. R. China.
E-mail: gongpinggp@126.com
Fax: þ86 24 2398-6429
ß 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

2
X. Zhai et al.
Arch. Pharm. Chem. Life Sci. 2012, 000, 1–8
sorafenib led to the discovery of an interesting class of
compounds containing the N-methyl-4-phenoxypicolinamide
motif [14, 15].
available picolinic acid in thionyl chloride to afford 2, which
was subsequently reacted with 2.0 M methyl amine in tetra-
hydrofuran to give compound 3 as pale-yellow crystals.
Intermediate 4 was obtained by etherification of 3 with 4-
aminophenol, and compound 5 was prepared by reacting
intermediate 4 with thiophosgen in chloroform and sodium
bicarbonate. Treating 5 with ammonium hydroxide in diox-
ane at 08C yielded the primary thiourea 6. Subsequently,
heterocyclization of 6 with ethyl chloroacetate furnished
the key intermediate 7 in the presence of sodium acetate.
Knoevenagal condensation of 7 and different substituted
aromatic aldehydes was accelerated employing sodium
acetate as catalyst in acetic acid under microwave irradia-
tion, which led to the formation of the target compounds 8a–
8y with a yield of ꢀ40 to ꢀ80%.
Chemical and biological properties of 2-iminothiazolidin-4-
ones prompted us to design a series of 4-(4-((5-benzylidene-4-
oxothiazolidin-2-ylidene)amino)phenoxy)-N-methylpicolinamides
(Figure 1) in continuation of our interest in optimizations of
sorafenib. Herein, the N-methyl-4-phenoxypicolinamide motif
of sorafenib was preserved, the 2-iminothiazolidin-4-one motif
was hybridized with the C-4’ position of the N-methyl-4-
phenoxypicolinamide scaffold, furthermore, arylidene group
was incorporated into the C-500 position of the 2-iminothiazo-
lidin-4-one motif to construct a bioisoster of the aryl urea.
23 benzylidenes (substituted by –F, –Cl, –Br, –OH, –OMe) and
2 heterocyclidenes (pyridin-4-ylmethylene, thiophen-2-ylmethyl-
ene) were incorporated to study the influence of the substi-
tution position and the electronic effect of the arylidene motif.
Further studies focusing on modifications of the N-methyl-4-
phenoxypicolinamide scaffold and introduction of other
thiazole-based heterocyclic nucleus are in progress in our
laboratories and will be reported upon soon.
First screening for biological activities
Antiproliferative activities of compound 7 and target com-
pounds 8a–8y were evaluated by MTT assay employing three
human cancer cell lines (human lung carcinoma cells
A549, human lung carcinoma cells H460 and human colon
carcinoma cells HT29). Some of the compounds exhibited
remarkable antiproliferative activity against one or more
cell lines in low micromolar range as shown in Table 1.
Especially, the most promising compound 8s (with IC50
values of 1.1, 0.01 and 1.3 mM against the A549, H460 and
HT29 cell lines, respectively) is 1.1, 270 and 2.8 fold more
Results and discussion
Chemistry
The synthetic route was illustrated as outlined in Scheme 1.
The synthesis was initiated by chloration of the commercially
Cl
O
N
N
N
O
NH
H
N
H
N
NH
CF3
Cl
O
N
O
N
O
O
N
H
H
N
N
N
H
N
O
Compound 2
Compound 1
O
O
Sorafenib
Aryl urea modified sorafenib analogs
R
1' '
1' '
e
H t
N
N
S
S
5' '
5' '
HN
HN
O
O
N
O
O
H
N
H
N
N
_
_
8a 8w
8x 8y
O
O
The structures of target compounds
Figure 1. The structures of sorafenib, aryl urea modified sorafenib analogs and the target compounds.
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Arch. Pharm. Chem. Life Sci. 2012, 000, 1–8
2-Iminothiazolidin-4-one Moiety-Containing Compounds
3
NH2
l
C
l
C
O
a
b
c
H
N
H
N
N
H
COO
N
N
l
COC
N
O
S
O
4
1
2
3
H
N
NH2
N
N
S
CS
HN
O
N
O
N
O
N
O
e
f
d
H
N
H
N
H
N
O
O
O
7
6
5
r
A
N
S
HN
O
g
O
a:
:
m:
n:
o:
:
=
=
8
R 3
8
8
8
R 2 4 6-trimethoxy
, ,
,4,5-trimethoxy
,3,4-trimethoxy
,5-dimethoxy
.
=
=
8b R 2
R 3 5-dibromo-4-hydroxy
,
H
N
c:
8
:
=
=
=
=
2
2-hydroxynaphthalen
R
R
R
R
N
8d
8
8
8
8
2-hydroxy
3 5-dimethoxy
p
e:
:
=
R H
=
8
R 4-hydroxy
O
q
8
:
r:
s:
:
=
=
R 2-fluoro
8f R 2,3,4-trihydroxy
:
:
=
=
4-fluoro
8
2
R
R
,3-dichloro
g
-benzo[d][1',3']dioxole
=
=
,
8h R 4
8t R 2 4-difluoro
:
=
u:
v:
=
R 3 4-difluoro
,
8i R 3,4-dihydroxy
8
:
:
=
=
R 4-methoxy
8
R 3-methoxy-4-hydroxy
8
j
w:
=
8
8
8
R 4-trifluoromethyl
=
8k R 3-hydroxy-4-methoxy
x:
=
=
thiophen-2-yl
:
R
R
=
8l R 2
,4-dimethoxy
:
y
pyridin-4-yl
Scheme 1. Reagents and conditions: a) SOCl2/DMF, 508C 10 min, r.f. 17 h; b) CH3NH2/THF/MeOH, 08C, then ambient temperature 2 h;
c) 4-aminophenol/t-BuOK/DMF, 808C, 6 h; d) 6% NaHCO3/CH2Cl2/thiophosgene, 08C, then r.t. 5 h; e) NH4OH/dioxane, 08C, 1 h; f) ethyl
chloroacetate/AcONa/EtOH, 608C, 6 h; g) AcONa/AcOH, microwave, 12 min.
potent than the reference drug sorafenib. In addition,
compound 8r exhibited optimal activity against the HT29
and A549 cell lines with IC50 values of 1.1 and 0.9 mM among
the tested compounds.
As shown in Table 1, it was obvious that the introduction of
substituents on the meta-position of the benzylidene weak-
ened or even abolished antitumor activity against the three
cell lines. It is noteworthy that the nature of the substituents
on the benzylidene affects the antitumor activity at different
degrees. Among the tested compounds, fluorine atom is the
most preferable substitution group (e.g. 8r, 8t and the most
promising compound 8s showed more potent antitumor
activity among the tested compounds in one or more cell
lines), while other electron withdrawing groups showed no
evident influence on potency. Some electron donating group
including hydroxyl group and methoxy group exhibited
moderate to significant influence on the antitumor activity.
In conclusion, the SARs summarized may provide guidance
for further design and discovery of 2-iminothiazolidin-4-one
based antiproliferative agents.
The preliminary structure-activity relationships (SARs)
suggested that substituted arylidene on C-5’’ position of 2-
iminothiazolidin-4-one ring is essential for the antiprolifer-
ative activity. A case in point is that compound 7 without
substitution of arylidene moiety exhibited less antitumor
activity than the target compounds. Introduction of hetero-
cyclidene (e.g. 8x and 8y) led to weakened antitumor activity,
while it was opposite in that the introduction of benzylidene
showed enhanced antitumor activity in most compounds.
Pharmacological data indicated that the substitution pos-
ition of the substituents on the benzylidene influences the
antitumor activities of the target compounds dramatically.
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4
X. Zhai et al.
Arch. Pharm. Chem. Life Sci. 2012, 000, 1–8
Table 1. IC50 for tested compounds 8a–y (in mM) against A549, H460 and HT29 cancer cell lines
N
S
R
R
N
S
N
S
HN
HN
O
N
HN
O
N
O
O
N
O
O
H
N
H
N
H
N
7
_
_
8a 8w
O
8x 8y
O
O
.
Compd.
R
IC50 (mM)
A549
H460
HT29
7
8a
8b
8c
8d
8e
–
38.6
27.1
97.0
7.6
NAa
3.8
83.2
4.1
47.2
37.0
NA
39.5
13.0
5.6
25.2
NA
2.8
3,4,5-trimethoxy
2,3,4-trimethoxy
2,5-dimethoxy
3,5-dimethoxy
–
3.0
8f
2,3,4-trihydroxy
2,3-dichloro
25.9
NA
NA
17.1
NA
NA
5.6
11.4
72.2
9.1
1.7
3.2
0.9
1.1
8.9
NA
39.7
NA
88.3
19.6
48.5
NA
4.2
1.8
16.8
8.1
0.3
4.7
1.2
0.01
0.3
NA
4.1
NA
NA
NA
27.9
4.4
NA
1.3
5.0
5.2
1.9
3.1
14.6
1.1
1.3
2.2
3.7
8g
8h
8i
8j
8k
8l
8m
8n
8o
8p
8q
8r
8s
8t
8u
8v
4-benzo[d][1’,3’]dioxole
3,4-dihydroxy
3-methoxy-4-hydroxy
3-hydroxy-4-methoxy
2,4-dimethoxy
2,4,6-trimethoxy
3,5-dibromo-4-hydroxy
2-hydroxynaphthalene
2-hydroxy
4-hydroxy
2-fluoro
4-fluoro
2,4-difluoro
3,4-difluoro
4-methoxy
3.3
NA
40.4
20.9
1.3
NA
NA
19.3
29.1
3.7
8w
8x
8y
4-trifluoromethyl
thiophen-2-yl
pyridin-4-yl
NA
22.8
46.5
2.7
Sorafenib
–
a
NA means not active, the IC50 of which is more than 100 mM
silica gel (200–300 mesh) from Qingdao Ocean Chemicals
(Qingdao, Shandong, China). Unless otherwise noted, all the
materials were obtained from commercially available sources
and were used without further purification.
Experimental protocols
Chemistry
All melting points were obtained on a Bu¨chi Melting Point B-540
apparatus (Bu¨chi Labortechnik, Flawil, Switzerland) and were
uncorrected. Mass spectra (MS) were taken in ESI mode on
Agilent 1100 LC-MS (Agilent, Palo Alto, CA, USA). Proton (1H)
nuclear magnetic resonance spectroscopy was performed using
Bruker ARX-300, 300MHz spectrometers (Bruker Bioscience,
Billerica, MA, USA) with TMS as internal standard. Reactions
under microwaves were performed in a CEM Discover1 mono-
mode microwave reactor. Column chromatography was run on
4-Chloropicolinoyl chloride (2)
Anhydrous N,N-dimethylformamide (0.1 mL) was added to thion-
yl chloride (90 mL) at 508C under nitrogen. The solution was
stirred at 508C for 10 min prior to portionwise addition of
picolinic acid 1 (30 g, 0.244 mol) over 30 min. The initial green
color went to orange and then to purple. The solution was heated
to reflux, and vigorous SO2 evolution was observed. A yellow
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Arch. Pharm. Chem. Life Sci. 2012, 000, 1–8
2-Iminothiazolidin-4-one Moiety-Containing Compounds
5
solid precipitated after 17 h. The mixture was then cooled to
room temperature, diluted with toluene (200 mL), and concen-
trated under reduced pressure to 70 mL. This process was
repeated two additional times to give 2 as a brown oil which
was used in the next step without further purification.
1H), 7.20–7.14 (m, 3H), 2.79 (d, J ¼ 4.8 Hz, 3H); ESI-MS m/z: 303.1
(MþH)þ.
N-Methyl-4-(4-(4-oxo-4,5-dihydrothiazol-2-ylamino)-
phenoxy)picolinamide (7)
To a stirred suspension of thiourea 6 (1.81g, 6.0 mmol) and
anhydrous sodium acetate (2.48 g, 30.0 mmol) in 20 mL of
absolute ethanol was added 1.42 mL (12.0 mmol) of ethyl chlor-
oacetate. The mixture was heated at 608C for 6 h. After being
cooled to room temperature, the solvent was evaporated under
reduced pressure, 10 mL water was added to form precipitates.
The precipitates were filtered and washed with ethanol to pro-
duce the crude product. The crude product was recrystallized
from ethanol to produce 2-arylimino-thiazolidin-4-one 7 (1.58 g,
4.62 mmol, 77%). 1H-NMR (300 MHz, CDCl3) d: 8.43ꢂ8.41 (m, 1H),
8.07 (d, J ¼ 4.8 Hz, 1H), 7.74 (d, J ¼ 2.4 Hz, 1H), 7.33 (d, J ¼ 8.7 Hz,
2H), 7.15 (q, J ¼ 8.7 Hz, 2H), 7.02 (q, J ¼ 2.4 Hz, J ¼ 4.8 Hz, 1H),
3.92 (s, 1H), 3.03 (d, J ¼ 5.1 Hz, 3H); ESI-MS m/z: 342.3 (MþH)þ;
Anal. Calcd. for C16H14N4O3S (%): C 56.13, H 4.12, N 16.36, O 14.02,
S 9.37; found C 56.20, H 4.24, N 16.49, S 9.45.
4-Chloro-N-methylpicolinamide (3)
4-Chloropicolinoyl chloride 2 (20.0 g, 113.7 mmol) was added por-
tionwise to 2.0 M methylamine in tetrahydrofuran (350 mL) and
methanol (70 mL) at 08C. The mixture was stirred at ambient
temperature for 2 h, concentrated to near dryness, and dissolved
in ethyl acetate (350 mL). The organics were washed with brine
(350 mL), dried over sodium sulfate, and concentrated to provide 3
(16.0 g, 94.3 mmol, 83%) as a yellow, crystalline solid. m.p.: 41–428C.
1H-NMR (300 MHz, DMSO) d: 8.87–8.85 (m, 1H), 8.61 (d, J ¼ 5.1 Hz,
1H), 8.01 (d, J ¼ 2.4 Hz, 1H), 7.75–7.73 (q, J ¼ 2.4 Hz, J ¼ 5.7 Hz, 1H),
2.82 (d, J ¼ 5.1 Hz, 3H); ESI-MS m/z: 171.3 (MþH)þ.
4-(4-Aminophenoxy)-N-methylpicolinamide (4)
A solution of 4-aminophenol (9.6 g, 88.0 mmol) in dry N,N-
dimethylformamide (150 mL) was treated with potassium tert-
butoxide (10.29 g, 91.69 mmol), and the reddish-brown mixture
was stirred at room temperature for 2 h. The contents
were treated with 4-chloro-N-methylpicolinamide 3 (15.0 g,
87.9 mmol) and potassium carbonate (6.5 g, 47.0 mmol) and
then heated to 808C under nitrogen for 6 h. The mixture was
cooled to room temperature and poured into the mixture of
ethyl acetate (500 mL) and brine (500 mL). The layers were sep-
arated, and the aqueous phase was back-extracted with ethyl
acetate (300 mL). The combined organics were washed with brine
(4 ꢁ 300 mL), dried over sodium sulfate, and concentrated to
afford 4 (17.1 g, 70.3 mmol, 80%) as a purple solid. 1H-NMR
(300 MHz, DMSO) d: 8.74–8.72 (m, 1H), 8.45 (d, J ¼ 5.4 Hz, 1H),
7.34 (d, J ¼ 3 Hz, 1H), 7.07–7.05 (q, J ¼ 3 Hz, J ¼ 5.4 Hz, 1H), 6.87
(d, J ¼ 8.4 Hz, 2H), 6.66 (d, J ¼ 8.7 Hz, 2H), 2.78 (d, J ¼ 4.8 Hz,
3H); ESI-MS m/z: 244.0 (MþH)þ.
General procedure for preparation of compound (8a–8y)
A mixture of the aromatic aldehyde (1.0 mmol), 2-imino-4-thia-
zolidinone (1.0 mmol), sodium acetic (0.12 g, 1.5 mmol), and
acetic acid (5 mL) was placed in a flask sealed with a cap con-
taining a septum. The flask was then placed into the cavity of the
microwave reactor and heated at 150 W, 1608C for 6 min twice.
After cooling to ambient temperature, 20 mL water was added
and the mixture was allowed to being stirred for 10 mins. The
participate formed was filtered, some crude product was recrys-
tallized from ethanol, other crude product was purified by
chromatography on silica gel using MeOH/CH2Cl2 to afford
the solids 8a–8y.
(E)-N-Methyl-4-(4-(4-oxo-5-(3,4,5-trimethoxybenzylidene)-
4,5-dihydrothiazol-2-ylamino)phenoxy)picolinamide (8a)
1
Yield: 61%. m.p.: 233–2348C. H-NMR (300 MHz, DMSO) d: 8.79–
4-(4-Isothiocyanatophenoxy)-N-methylpicolinamide (5)
To a stirred solution of 4-(4-aminophenoxy)-N-methylpicolin-
amide 4 (17.1 g, 70.3 mmol) in 1300 mL of 6% NaHCO3 solution
was added 600 mL CH2Cl2. After 20 min of vigorous stirring at
08C, thiophosgene (4.1 mL, 70.3 mmol) was added dropwise. The
reaction mixture was left under stirring for 5 h at room tempera-
ture, and the organic solvent was removed under reduced pres-
sure and the crude residue was washed with cold ethanol to
afford 5 (15.4 g, 54.1 mmol, 77%) as a brown powder. 1H-NMR
(300 MHz, DMSO) d: 8.79–8.78 (m, 1H), 8.54 (d, J ¼ 6 Hz, 1H), 7.59
(d, J ¼ 9.3 Hz, 2H), 7.43 (d, J ¼ 3 Hz, 1H), 7.32 (d, J ¼ 8.7 Hz, 2H),
7.20–7.17 (q, J ¼ 3 Hz, J ¼ 6 Hz, 1H), 2.80 (d, J ¼ 4.5 Hz, 3H);
ESI-MS m/z: 286.2 (MþH)þ.
8.77 (m, 1H), 8.54 (d, J ¼ 6.0 Hz, 1H), 7.93 (d, J ¼ 9.0 Hz, 1H), 7.71
(s, 1H), 7.42 (d, J ¼ 2.7 Hz, 1H), 7.34–7.25 (m, 2H), 7.21–7.17
(m, 2H), 6.99 (s, 1H), 6.88 (s, 1H), 3.79 (s, 6H), 3.80 (s, 3H), 2.80
(d, J ¼ 4.5 Hz, 3H); ESI-MS m/z: 521.5 (MþH)þ; Anal. Calcd.
for C26H24N4O6S (%): C 59.99, H 4.65, N 10.76, O 18.44, S 6.16;
found C 60.08, H 4.66, N 11.03, S 6.22.
(E)-N-Methyl-4-(4-(4-oxo-5-(2,3,4-trimethoxybenzylidene)-
4,5-dihydrothiazol-2-ylamino)phenoxy)picolinamide (8b)
1
Yield: 63%. m.p.: 267–2688C. H-NMR (300 MHz, DMSO) d: 8.44–
8.42 (m, 1H), 8.15–8.04 (br, 2H), 7.80 (d, J ¼ 2.7 Hz, 1H), 7.27–7.20
(m, 3H), 7.17–7.13 (m, 2H), 7.04–7.01 (q, J ¼ 3.0 Hz, J ¼ 2.7 Hz,
1 H), 6.79 (d, J ¼ 8.7 Hz, 1H), 3.88 (s, 3H), 3.87 (s, 3H), 3.86 (s, 3H),
3.04 (d, J ¼ 5.4 Hz, 3H); ESI-MS m/z: 521.8 (MþH)þ; Anal. Calcd.
for C26H24N4O6S2 (%): C 59.99, H 4.65, N 10.76, O 18.44, S 6.16;
found C 59.85, H 4.71, N 10.65, S 6.00.
N-Methyl-4-(4-thioureidophenoxy)picolinamide (6)
To a mixture of ammonium hydroxide (10 mL) and dioxane
(60 mL) was added 5 (15.4 g, 54.1 mmol), and the temperature
was kept at 08C for a period of 1 h until most participated from
the reaction mixture. Crude product was obtained after filtration.
The solid obtained was recrystallized in ethanol to yield an off
white solid 6 (13.1 g, 43.2 mmol, 80%) after filtration. m.p.: 72–
738C. 1H-NMR (300 MHz, DMSO) d: 9.77 (br, 1H), 8.79–8.78 (m, 1H),
8.52 (d, J ¼ 6.0 Hz, 1H), 7.54 (d, J ¼ 9.0 Hz, 2H), 7.42 (d, J ¼ 2.7 Hz,
(E)-4-(4-(5-(2,5-Dimethoxybenzylidene)-4-oxo-4,5-
dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolinamide
(8c)
1
Yield: 66%. m.p.: 233–2348C. H-NMR (300 MHz, DMSO) d: 8.44–
8.42 (m, 1H), 8.59 (br, 2H), 7.82 (d, J ¼ 2.4 Hz, 1H), 7.22–7.12
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www.archpharm.com

6
X. Zhai et al.
Arch. Pharm. Chem. Life Sci. 2012, 000, 1–8
(m, 4H), 7.04–7.01 (q, J ¼ 2.4 Hz, J ¼ 4.8 Hz, 1H), 6.95 (s, 1H), 6.92
(d, J ¼ 2.4 Hz, 1H), 6.88 (d, J ¼ 2.4 Hz, 1H), 3.8 (s, 3H), 3.79 (s, 3H),
3.05 (d, J ¼ 5.1 Hz, 3H); ESI-MS m/z: 491.2 (MþH)þ; Anal. Calcd. for
C25H22N4O5S (%): C 61.21, H 4.52, N 11.42, O 16.31, S 6.54; found
C 61.30, H 4.70, N 11.40, S 6.66.
7.23 (d, J ¼ 9.0 Hz, 2H), 7.17 (d, J ¼ 9.0 Hz, 2H), 7.06–7.01
(m, 2 H), 6.97 (s, 1 H), 6.92 (d, J ¼ 9.0 Hz, 1 H), 6.04 (s, 2H),
3.05 (d, J ¼ 5.1 Hz, 2 H); ESI-MS m/z: 475.2 (MþH)þ; Anal.
Calcd. for C24H18N4O5S (%): C, 60.75; H, 3.82; N, 11.81;
O, 16.86; S, 6.76; found C 60.80, H 3.87, N 11.84, S 6.69.
(E)-4-(4-(5-(3,5-Dimethoxybenzylidene)-4-oxo-4,5-
dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolinamide
(8d)
(E)-4-(4-(5-(3,4-Dihydroxybenzylidene)-4-oxo-4,5-
dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolinamide
(8i)
Flash chromatography (silica gel, methylene chloride/methanol
(30:1)). Yield: 52%. m.p.: 231–2328C. 1H-NMR (300 MHz, CDCl3)
d: 8.44–8.42 (m, 1H), 8.09 (d, J ¼ 6.0 Hz, 1H), 7.81 (s, 1H), 7.70
(s, 1H), 7.22 (d, J ¼ 9.0 Hz, 2H), 7.16 (d, J ¼ 9.0 Hz, 2H), 7.04–7.01
(q, J ¼ 3.0 Hz, J ¼ 6.0 Hz, 1H), 6.62 (s, 2H), 6.51 (s, 1H), 3.82 (s, 6H),
3.05 (d, J ¼ 5.1 Hz, 3H); ESI-MS m/z: 491.3 (MþH)þ; Anal. Calcd.
for C25H22N4O5S (%): C 61.21, H 4.52, N 11.42, O 16.31, S 6.54;
found C 61.30, H 4.60, N 11.55, S 6.55.
Flash chromatography (silica gel, methylene chloride/methanol
(30:1)). Yield: 78%. m.p.: 261–2628C. 1H-NMR (300 MHz, DMSO)
d: 9.67 (br, 1H), 9.41 (br, 1H), 8.80–8.79 (m, 1H), 8.54 (d, J ¼ 5.7 Hz,
1H), 7.93 (d, J ¼ 9.0 Hz, 2H), 7.56 (s, 1H), 7.47 (d, J ¼ 4.2 Hz, 1H),
7.29 (d, J ¼ 9.3 Hz, 2H), 7.19–7.17 (m, 2H), 7.03–6.82 (m, 3H), 2.80
(d, J ¼ 4.2 Hz, 3H); ESI-MS m/z: 463.2 (MþH)þ; Anal. Calcd.
for C23H18N4O5S (%): C 59.73, H 3.92, N 12.11, O 17.30, S 6.93;
found C 59.91, H 3.97, N 12.24, S 7.01.
(E)-4-(4-(5-(4-Hydroxy-3-methoxybenzylidene)-4-oxo-4,5-
dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolinamide
(8j)
Flash chromatography (silica gel, methylene chloride/methanol
(25:1)). Yield: 55%. m.p.: 237–2388C. 1H-NMR (300 MHz, DMSO)
d: 9.85–9.80 (br, 1H), 8.79–8.77 (m, 1H), 8.54 (d, J ¼ 5.7 Hz, 1H),
7.93 (d, J ¼ 9.6 Hz, 1H), 7.57 (s, 1H), 7.42 (s, 1H), 7.33–7.26 (m, 2H),
7.20–7.10 (m, 3H), 7.00–6.90 (m, 2H), 3.85 (s, 3H), 2.81
(d, J ¼ 5.1 Hz, 3H); ESI-MS m/z: 572.7 (MþH)þ; Anal. Calcd.
for C24H20N4O5S (%): C 60.49, H 4.23, N 11.76, O 16.79, S 6.73;
found C 60.60, H 4.21, N 11.76, S 6.82.
(E)-4-(4-(5-Benzylidene-4-oxo-4,5-dihydrothiazol-2-
ylamino)phenoxy)-N-methylpicolinamide (8e)
Flash chromatography (silica gel, methylene chloride/methanol
(25:1)). Yield: 76%. m.p.: 249–2508C. 1H-NMR (300 MHz, DMSO)
d: 8.79–8.78 (m, 1H), 8.54 (d, J ¼ 5.1 Hz, 1H), 7.93 (d, J ¼ 6.3 Hz,
1H), 7.75 (s, 2H), 7.66 (d, J ¼ 9.0 Hz, 1H), 7.58–7.43 (m, 5H), 7.34
(d, J ¼ 8.7 Hz, 1H), 7.30 (d, J ¼ 8.7 Hz, 1H), 7.20–7.10 (m, 2H), 2.81
(d, J ¼ 4.2 Hz, 3H); ESI-MS m/z: 431.7 (MþH)þ; Anal. Calcd.
for C23H18N4O3S (%): C 64.17, H 4.21, N 13.01, O 11.15, S 7.45;
found C 63.88, H 4.17, N 12.99, S 7.27.
(E)-N-Methyl-4-(4-(4-oxo-5-(2,3,4-trihydroxybenzylidene)-
(E)-4-(4-(5-(3-Hydroxy-4-methoxybenzylidene)-4-oxo-4,5-
dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolinamide
(8k)
Flash chromatography (silica gel, methylene chloride/methanol
(30:1)). Yield: 67%. m.p.: 243–2448C. 1H-NMR (300 MHz, DMSO)
d: 9.47–9.45 (br, 1H), 8.81–8.79 (m, 1H), 8.54 (d, J ¼ 5.7 Hz, 1H),
7.93 (d, J ¼ 7.5 Hz, 1H), 7.45 (d, J ¼ 9.0 Hz, 1H), 7.29
(d, J ¼ 9.0 Hz, 2H), 7.20–7.19 (m, 2H), 7.09–6.97 (m, 2H), 3.84
(s, 3H), 2.80 (d, J ¼ 4.2 Hz, 3H); ESI-MS m/z: 477.5 (MþH)þ; Anal.
Calcd. for C24H20N4O5S (%): C 60.49, H 4.23, N 11.76, O 16.79,
S 6.73; found C 60.41, H 4.28, N 11.82, S 6.81.
4,5-dihydrothiazol-2-ylamino)phenoxy)picolinamide (8f)
Flash chromatography (silica gel, methylene chloride/methanol
(30:1)). Yield: 68%. m.p.: 255–2578C. 1H-NMR (300 MHz, DMSO)
d: 8.78–8.77 (m, 1H), 8.59 (d, J ¼ 5.7 Hz, 1H), 8.53 (d, J ¼ 5.1 Hz,
1H), 7.91 (d, J ¼ 8.1 Hz, 1H), 7.83 (s, 1H), 7.79 (d, J ¼ 2.1 Hz, 1H),
7.65–7.49 (m, 2H), 7.41–7.38 (q, J ¼ 2.4 Hz, J ¼ 6.0 Hz, 1H), 7.33
(d, J ¼ 9.0 Hz, 1H), 7.27 (d, J ¼ 9.0 Hz, 1H), 7.21–7.15 (m, 2H), 2.80
(d, J ¼ 5.7 Hz, 3H); ESI-MS m/z: 479.1 (MþH)þ; Anal. Calcd.
for C23H18N4O6S (%): C 57.73, H 3.79, N 11.71, O 20.06, S 6.70;
found C 58.01, H 3.85, N 11.73, S 6.77.
(E)-4-(4-(5-(2,3-Dichlorobenzylidene)-4-oxo-4,5-
dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolinamide
(8g)
(E)-4-(4-(5-(2,4-Dimethoxybenzylidene)-4-oxo-4,5-
dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolinamide
Flash chromatography (silica gel, methylene chloride/methanol
(30:1)). Yield: 41%. m.p.: 252–2538C. 1H-NMR (300 MHz, DMSO)
d: 10.1 (br, 1H), 8.78–8.76 (m, 1H), 8.53 (d, J ¼ 5.4 Hz, 1H), 7.88
(d, J ¼ 5.7 Hz, 1H), 7.70–7.53 (m, 4H), 7.42 (s, 1H), 7.32
(d, J ¼ 9.0 Hz, 1H), 7.27 (d, J ¼ 8.7 Hz, 1H), 7.17–7.15 (m, 2H),
2.80 (d, J ¼ 3.0 Hz, 3H); ESI-MS m/z: 500.2 (MþH)þ; Anal. Calcd.
for C23H16N4O3S (%): C 55.32, H 3.23, N 11.22, O 9.61, S 6.42; found
C 55.51, H 3.37, N 11.19, S 6.48.
(8l)
Yield: 48%. m.p.: 229–2308C. 1H-NMR (300 MHz, CDCl3) d: 8.43–
8.41 (m, 1H), 8.12 (br, 2H), 7.82 (d, J ¼ 2.7 Hz, 1H), 7.17–7.12
(m, 4H), 7.03–7.00 (q, J ¼ 3.0 Hz, J ¼ 6.0 Hz, 2H), 6.95
(d, J ¼ 7.8 Hz, 1H), 6.89 (d, J ¼ 8.1 Hz, 1H), 3.85 (s, 3H), 3.79
(s, 3H), 3.05 (d, J ¼ 5.4 Hz, 3H); ESI-MS m/z: 491.7 (MþH)þ;
Anal. Calcd. for C25H22N4O5S (%): C 61.21, H 4.52, N 11.42,
O 16.31, S 6.54; found C 61.30, H 4.65, N 11.47, S 6.60.
(E)-4-(4-(5-(Benzo[d][1,3]dioxol-5-ylmethylene)-4-oxo-
4,5-dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolin-
amide (8h)
(E)-N-Methyl-4-(4-(4-oxo-5-(2,4,6-trimethoxy-
benzylidene)-4,5-dihydrothiazol-2-ylamino)phenoxy)-
picolinamide (8m)
Flash chromatography (silica gel, methylene chloride/methanol
Yield: 73%. m.p.: 244–2458C. 1H-NMR (300 MHz, CDCl3) d: 8.44–
8.42 (m, 1H), 8.08 (d, J ¼ 4.8 Hz, 1 H), 7.81 (s, 1 H), 7.68 (s, 1 H),
(25:1)). Yield: 76%. m.p.: 251–2528C. 1H-NMR (300 MHz, CDCl3)
ß 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

Arch. Pharm. Chem. Life Sci. 2012, 000, 1–8
2-Iminothiazolidin-4-one Moiety-Containing Compounds
7
d: 8.41–8.39 (m, 1H), 8.06 (br, 2H), 7.77 (d, J ¼ 2.4 Hz,1H), 7.20–
7.11 (m, 4H), 7.00–6.97 (q, J ¼ 4.2 Hz, J ¼ 7.5 Hz, 1H), 6.10 (s, 2H),
3.86 (s, 6H), 3.82 (s, 3H), 3.04 (d, J ¼ 5.4 Hz, 3H); ESI-MS m/z: 521.9
(MþH)þ; Anal. Calcd. for C26H24N4O6S (%): C 59.99, H 4.65,
N 10.76, O 18.44, S 6.16; found C 60.11, H 4.71, N 10.82, S 6.21.
1H), 7.78 (s, 1H), 7.51 (d, J ¼ 5.7 Hz, 1H), 7.42–7.28 (m, 5H), 7.19
(br, 2H), 2.79 (d, J ¼ 4.2 Hz, 3H); ESI-MS m/z: 449.2 (MþH)þ; Anal.
Calcd. for C23H17FN4O3S (%): C 61.60, H 3.82, N 12.49, O 10.70,
S 7.15; found C 61.71, H 3.99, N 12.63, S 7.32.
(E)-4-(4-(5-(4-Fluorobenzylidene)-4-oxo-4,5-
dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolinamide
(E)-4-(4-(5-(3,5-Dibromo-4-hydroxybenzylidene)-4-oxo-
4,5-dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolin-
amide (8n)
Flash chromatography (silica gel, methylene chloride/methanol
(30:1)). Yield: 72%. m.p.: 236–2378C. 1H-NMR (300 MHz, DMSO)
d: 8.79–8.77 (m, 1H), 8.53 (d, J ¼ 5.4 Hz, 1H), 7.91 (d, J ¼ 8.4 Hz,
1H), 7.83 (s, 1H), 7.70 (s, 1H), 7.64 (s, 1H), 7.46–7.41 (q, J ¼ 2.1 Hz,
J ¼ 6.0 Hz, 1H), 7.43–7.28 (m, 2H), 7.21–7.16 (m, 2H), 2.80
(d, J ¼ 4.8 Hz, 3H); ESI-MS m/z: 604.1 (MþH)þ; Anal. Calcd.
for C23H16Br2N4O4S (%): C 45.72, H 2.67, N 9.27, O 10.59,
S 5.31; found C 45.70, H 2.71, N 9.23, S 3.36.
(8s)
Yield: 65%. m.p.: 237–2388C. 1H-NMR (300 MHz, CDCl3) d: 8.13–
8.12 (m, 1H), 7.79 (d, J ¼ 2.7 Hz, 1 H), 7.74 (s, 1 H), 7.52–7.47
(m, 2H), 7.21–7.15 (m, 6 H), 7.08–7.05 (q, J ¼ 2.7 Hz, J ¼ 5.7 Hz,
1 H), 2.81 (d, J ¼ 4.8 Hz, 3 H); ESI-MS m/z: 449.2 (MþH)þ; Anal.
Calcd. for C23H17FN4O3S (%): C 61.60, H 3.82, N 12.49, O 10.70,
S 7.15; found C 61.75, H 4.03, N 12.50, S 10.74.
(E)-4-(4-(5-(2,4-Difluorobenzylidene)-4-oxo-4,5-
dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolinamide
(8t)
Flash chromatography (silica gel, methylene chloride/methanol
(30:1)). Yield: 68%. m.p.: 228–2298C. 1H-NMR (300 MHz, DMSO)
d: 8.79–8.78 (m, 1H), 8.54 (d, J ¼ 5.7Hz, 1H), 7.91 (d, J ¼ 8.1 Hz,
1H), 7.69–7.39 (m, 4H), 7.32–7.26 (q, J ¼ 8.7 Hz, J ¼ 12.0 Hz, 3H),
7.19 (d, J ¼ 8.4 Hz, 2H), 2.79 (d, J ¼ 5.1 Hz, 3H); ESI-MS m/z: 467.0
(MþH)þ; Anal. Calcd. for C23H16F2N4O3S (%): C 59.22, H 3.46,
N 12.01, O 10.29, S 6.87; found C 59.17, H 3.51, N 12.00, S 6.81.
(E)-4-(4-(5-((2-Hydroxynaphthalen-1-yl)methylene)-4-oxo-
4,5-dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolin-
amide (8o)
1
Yield: 47%. m.p.: 261–2628C. H-NMR (300 MHz, DMSO) d: 10.67
(br, 1H), 8.77–8.76 (m, 1H), 8.59 (d, J ¼ 5.7 Hz, 1H), 8.09 (s, 1H),
7.91–7.82 (m, 3H), 7.78–7.69 (q, J ¼ 6.0 Hz, J ¼ 9.0 Hz, 1H), 7.78–
7.69 (m, 1H), 7.41–7.24 (m, 3H), 7.19 (d, J ¼ 8.7 Hz, 2H), 7.10
(d, J ¼ 8.7 Hz, 2H), 2.79 (d, J ¼ 4.2 Hz, 3H); ESI-MS m/z: 497.3
(MþH)þ; Anal. Calcd. for C27H20N4O4S (%): C 65.31, H 4.06,
N 11.28, O 12.89, S 6.46; found C 65.22, H 4.11, N 11.31, S 6.51.
(E)-4-(4-(5-(3,4-Difluorobenzylidene)-4-oxo-4,5-
dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolinamide
(8u)
Flash chromatography (silica gel, methylene chloride/methanol
(30:1)). Yield: 45%. m.p.: 242–2438C. 1H-NMR (300 MHz, DMSO)
d: 8.80–8.78 (m, 1H), 8.54 (d, J ¼ 5.7 Hz, 1H), 7.91 (d, J ¼ 8.7 Hz,
1H), 7.72–7.57 (m, 3H), 7.51–7.39 (m, 2H), 7.33–7.26 (q, J ¼ 9.0 Hz,
J ¼ 11.4 Hz, 2H), 7.20–7.17 (ms, 2H), 2.80 (d, J ¼ 4.2 Hz, 3H);
ESI-MS m/z: 467.0 (MþH)þ; Anal. Calcd. for C23H16F2N4O3S (%):
C 59.22, H 3.46, N 12.01, O 10.29, S 6.87; found C 59.30, H 3.55,
N 12.03, S 6.85.
(E)-4-(4-(5-(2-Hydroxybenzylidene)-4-oxo-4,5-
dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolinamide
(8p)
Flash chromatography (silica gel, methylene chloride/methanol
(25:1)). Yield: 59%. m.p.: 247–2488C. 1H-NMR (300 MHz, CDCl3)
d: 8.50–8.48 (m, 1H), 8.32 (d, J ¼ 4.2 Hz, 1H), 8.09 (s, 1H), 7.60
(d, J ¼ 2.7 Hz, 1H), 7.43 (d, J ¼ 9.0 Hz, 1H), 7.29–7.20 (m, 4H),
7.14–7.12 (q, J ¼ 3.0 Hz, J ¼ 4.2 Hz, 2H), 7.04 (d, J ¼ 3.6 Hz, 1H),
7.01 (d, J ¼ 3.6 Hz, 1H), 2.97 (d, J ¼ 4.8 Hz, 3H); ESI-MS m/z: 447.8
(MþH)þ; Anal. Calcd. for C23H18N4O4S (%): C 61.87, H 4.06,
N 12.55, O 14.33, S 7.18; found C 62.01, H 4.14, N 12.71, S 7.22.
(E)-4-(4-(5-(4-Methoxybenzylidene)-4-oxo-4,5-
dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolinamide
(8v)
Flash chromatography (silica gel, methylene chloride/methanol
(30:1)). Yield: 73%. m.p.: 225–2268C. 1H-NMR (300 MHz, DMSO)
d: 8.80–8.78 (m, 1H), 8.54 (d, J ¼ 5.4 Hz, 1H), 7.92 (d, J ¼ 87. Hz,
1H), 7.71 (s, 1H), 7.54 (d, J ¼ 8.7 Hz, 1H), 7.43–7.42 (m, 2H), 7.37–
7.26 (m, 4H), 7.17–7.17 (m, 2H), 2.80 (s, 3H), 2.23 (d, J ¼ 4.2 Hz,
3H); ESI-MS m/z: 461.7 (MþH)þ; Anal. Calcd. for C24H20N4O4S (%):
C 62.60, H 4.38, N 12.17, O 13.90, S 6.96; found C 62.72, H 4.50,
N 12.31, S 7.01.
(E)-4-(4-(5-(4-Hydroxybenzylidene)-4-oxo-4,5-
dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolinamide
(8q)
1
Yield: 63%. m.p.: 227–2288C. H-NMR (300 MHz, DMSO) d: 10.21
(br, 1H), 8.80–8.78 (m, 1H), 8.54 (d, J ¼ 5.4 Hz, 1H), 7.93
(d, J ¼ 9.0 Hz, 1H), 7.56–7.34 (m, 3H), 7.29 (d, J ¼ 9.0 Hz, 2 H),
7.19 (d, J ¼ 9.0 Hz, 2H), 6.96–6.88 (m, 2 H), 2.79 (d, J ¼ 4.8 Hz,
3H); ESI-MS m/z: 447.8 (MþH)þ; Anal. Calcd. for C23H18N4O4S (%):
C 61.87, H 4.06, N 12.55, O 14.33, S 7.18; found C 62.85, H 4.22,
N 12.63, S 7.09.
(E)-N-Methyl-4-(4-(4-oxo-5-(4-(trifluoromethyl)-
benzylidene)-4,5-dihydrothiazol-2-ylamino)phenoxy)-
(E)-4-(4-(5-(2-Fluorobenzylidene)-4-oxo-4,5-
dihydrothiazol-2-ylamino)phenoxy)-N-methylpicolinamide
(8r)
Flash chromatography (silica gel, methylene chloride/methanol
(30:1)). Yield: 42%. m.p.: 221–2118C. 1H-NMR (300 MHz, DMSO)
d: 8.79–8.78 (m, 1H), 8.54 (d, J ¼ 5.4 Hz, 1H), 7.93 (d, J ¼ 9.0 Hz,
picolinamide (8w)
Yield: 53%. m.p.: 243–2448C. 1H-NMR (300 MHz, CDCl3) d: 8.46–8.44
(m, 1H), 8.11 (d, J ¼ 4.5 Hz, 1H), 7.78 (d, J ¼ 2.4 Hz, 2H), 7.75 (s, 1H),
7.55 (d, J ¼ 8.7 Hz, 2H), 7.34 (d, J ¼ 8.7 Hz, 2H), 7.25 (d, J ¼ 8.7 Hz,
1H), 7.18 (d, J ¼ 8.7 Hz, 1H), 7.08–7.05 (q, J ¼ 2.7 Hz, J ¼ 6.0 Hz,
1H), 3.05 (d, J ¼ 5.1 Hz, 3H); ESI-MS m/z: 499.7 (MþH)þ; Anal. Calcd.
ß 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

8
X. Zhai et al.
Arch. Pharm. Chem. Life Sci. 2012, 000, 1–8
for C24H17F3N4O3S (%): C 57.83, H 3.44, F 11.43, N 11.24, O 9.63,
S 6.43; found C 57.99, H 3.52, N 11.26, S 6.45.
formazan) and 630 nm (for the reference wavelength) was
measured with an ELISA reader. All of the compounds were
tested at six concentrations in each cell line and the optical
density (OD) values were measured. Furthermore, the inhibition
rate of cell survival was caculated and the results expressed as
IC50 values were calculated by regression analysis by means of
SPSS.
(E)-N-Methyl-4-(4-(4-oxo-5-(thiophen-2-ylmethylene)-4,5-
dihydrothiazol-2-ylamino)phenoxy)picolinamide (8x)
Flash chromatography (silica gel, methylene chloride/methanol
(25:1)). Yield: 73%. m.p.: 225–2268C. 1H-NMR (300 MHz, DMSO)
d: 8.79–8.78 (m, 1H), 8.55 (d, J ¼ 5.1 Hz, 1H), 7.98–7.88 (m, 3H),
7.65–7.59 (m, 1H), 7.43–7.42 (m, 1H), 7.33–7.19 (m, 5H), 2.81
(d, J ¼ 4.8 Hz, 3H); ESI-MS m/z: 437.5 (MþH)þ; Anal. Calcd.
for C21H16N4O3S2 (%): C 57.78, H 3.69, N 12.84, O 11.00
S 14.69; found C 57.83, H 3.77, N 12.91, S 14.81.
This work was supported by a grant from the National Natural Science
Foundation of China (No. 21002065) and National S & T Major Project
(No.2009ZX09301-012).
The authors have declared no conflict of interest.
(E)-N-Methyl-4-(4-(4-oxo-5-(pyridin-4-ylmethylene)-4,5-
dihydrothiazol-2-ylamino)phenoxy)picolinamide (8y)
Yield: 57%. m.p.: 232–2338C. H-NMR (300 MHz, DMSO) d: 8.80–
References
1
8.78 (m, 1H), 8.75 (d, J ¼ 6.0 Hz, 1H), 8.69 (d, J ¼ 6.0 Hz, 1H),
8.57–8.52 (q, J ¼ 3.0 Hz, J ¼ 6.0 Hz, 1H), 7.92 (d, J ¼ 7.5 Hz, 2H),
7.70 (s, 1H), 7.58 (d, J ¼ 5.7 Hz, 1H), 7.49 (d, J ¼ 5.7 Hz, 1H), 7.42
(d, J ¼ 2.7 Hz, 1H), 7.35 (d, J ¼ 9.0 Hz, 1H), 7.31 (d, J ¼ 9.0 Hz,
1H), 7.21–7.18 (m, 2H), 2.81 (d, J ¼ 5.1 Hz, 3H); ESI-MS m/z: 432.3
(MþH)þ; Anal. Calcd. for C22H17N5O3S (%): C 61.24, H 3.97,
N 16.23, O 11.12, S 7.43; found C 61.33, H 4.05, N 16.44, S 7.27.
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compounds to allow attachment to the wall of the plate. The test
compounds 8a–8y at the indicated final concentrations were
added to the culture medium and the cell cultures were con-
tinued for 72 h. Fresh MTT was added to each well at a terminal
concentration of 5 mg/mL and incubated with cells at 378C for
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