The synthesis of ethacrynic acid thiazole derivatives as glutathione S-transferase pi inhibitors

Article abstract of DOI:10.1016/j.bmc.2012.02.011

Glutathione S-transferase pi (GSTpi) is a phase II enzyme which protects cells from death and detoxifies chemotherapeutic agents in cancer cells. Ethacrynic acid (EA) is a weak GSTpi inhibitor. Structure modifications were done to improve the ability of EA to inhibit GSTpi activity. Eighteen EA thiazole derivatives were designed and synthesized. Compounds 9a, 9b and 9c with a replacement of carboxyl group of EA by a heterocyclic thiazole exhibited improvement over EA to inhibit GSTpi activity.

Full text of DOI:10.1016/j.bmc.2012.02.011

Bioorganic & Medicinal Chemistry 20 (2012) 2316–2322
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
The synthesis of ethacrynic acid thiazole derivatives as glutathione
S-transferase pi inhibitors
Ting Li a, Guyue Liu b, Hongcai Li a,c, Xinmei Yang a, Yongkui Jing d, Guisen Zhao a,
⇑
a School of Pharmaceutical Sciences, Shandong University, Jinan, Shandong 250012, PR China
b Shenyang Pharmaceutical University, Shenyang 110016, PR China
c Binzhou Polytechnic, Binzhou, Shandong 266603, PR China
d Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Glutathione S-transferase pi (GSTpi) is a phase II enzyme which protects cells from death and detoxifies
chemotherapeutic agents in cancer cells. Ethacrynic acid (EA) is a weak GSTpi inhibitor. Structure mod-
ifications were done to improve the ability of EA to inhibit GSTpi activity. Eighteen EA thiazole derivatives
were designed and synthesized. Compounds 9a, 9b and 9c with a replacement of carboxyl group of EA by
a heterocyclic thiazole exhibited improvement over EA to inhibit GSTpi activity.
Received 10 December 2011
Revised 3 February 2012
Accepted 3 February 2012
Available online 13 February 2012
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
EA thiazole derivatives
GSTpi inhibition
1. Introduction
substrate-binding site of the isozyme and by depleting GSH via
conjugation of the Michael addition to the thiol group of GSH.3,14
Glutathione transferases (GSTs) (EC 2.5.1.18) are a family of
Phase II detoxification enzymes in plants and animals. GSTs can
catalyse the conjugation of glutathione (GSH) to a wide range of
endogenous and exogenous electrophilic compounds to generate
less toxic and more water soluble products easily to be eliminated.
Among these enzymes, GSTpi is an abundant enzyme which also
has a role in the regulation of signaling pathway of cell death
and proliferation.1–4 GSTpi has been found to inhibit c-Jun N-ter-
minal kinase (JNK) through direct protein-protein interaction.5
GSTpi was also found to elicit protection against cell death induced
by reactive oxygen species (ROS).6 GSTpi was found to be able to
block tumor necrosis factor receptor-associated factor 2-apoptosis
signal-regulating kinase 1 (TRAF2–ASK1) interaction and to sup-
press TRAF2–ASK1-triggered cell death.7 Overexpression of GSTpi
suppressed mitogen-activated protein kinase/extracellular signal-
regulated kinase kinase kinase 1 (MEKK1)-mediated apoptosis in
HEK293 cells.8 In addition, GSTpi is linked to the forward S-glu-
tathionylation reaction of proteins, a critical process responded
to cellular stress.9–11 In view of the multiple functions of GSTpi
in protecting cancer cells from death,11,12 GSTpi inhibitors have po-
tential to be developed as therapeutic agents for cancer treatment.
Ethacrynic acid (EA), a known inhibitor of GSTpi, has been
shown to enhance the cytotoxicity of several anticancer agents.13
EA inhibits the activity of GSTpi by binding directly to the
Previously we have done structural modifications of EA by replac-
ing the carboxyl with esters or heterocyclic oxadiazole. The EA
derivatives containing heterocyclic oxadiazole showed better anti-
proliferative ability than EA but have variant ability of inhibiting
GSTpi activity.15 Recently it has been found that bromo-thiazolide
could bind to GSTpi and inhibit GSTpi activity.16 We designed and
synthesized 18 new EA derivatives using a thiazole group to re-
place carboxyl acid of EA and to compare their abilities of inhibit-
ing GSTpi activity as well as of inhibiting human leukemia HL-60
cell proliferation.
2. Results and discussion
2.1. Chemistry
The synthesis of thiazole derivatives from EA was shown in
Scheme 1. The intermediates 2 and 10 were obtained by the meth-
ods reported before.17
The intermediates 5 were synthesized in two routes. One is
started with the appropriate substituted phenols which reacted
with chloroacetic acid to generate compounds 2. With thionyl
chloride as a chlorinating agent and solvent, compounds 2 were
converted to acyl chlorides and then reacted with aqueous ammo-
nia at 0–5 °C to obtain acetamides 3. Phosphorus pentasulfide was
added to a solution of compounds 3 in tetrahydrofuran at 50 °C in
batches to yield ethanethioamides 4. The intermediates 5 were
obtained by Fridel–Crafts reaction of compounds 4. Most of
⇑
Corresponding author. Tel.: +86 531 88382009; fax: +86 531 88382835.
E-mail address: guisenzhao@sdu.edu.cn (G. Zhao).
0968-0896/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2012.02.011

T. Li et al. / Bioorg. Med. Chem. 20 (2012) 2316–2322
2317
R2
R1
R2
R1
R2
R1
R2
R1
vi
O
S
i, ii
iii, iv
v
OH
OCH2COOH
OCH2CNH2
OCH2CNH2
1
2
4
3
R2
R1
Cl
Cl
Cl
Cl
S
O
O
O
O
v
xi
OCH2CNH2
OCH2CNH2
OCH2COOH
R3
R3
R3
5
10
11
O
O
vii
viii
Br
R4
R4
CH3
7
6
R2
R1
R2
R1
O
O
S
OCH2
N
S
N
ix, x
OCH2
R3
R3
R4
R4
CH2
9
8
Scheme 1. Reagents and conditions: (i) NaOH, chloroacetic acid, 100 °C; (ii) HCl; (iii) SOCl2, 80 °C; (iv) NH3ÁH2O, 0–5 °C; (v) P2S5, THF, 50 °C; (vi) propionyl chloride or butyryl
chloride, AlCl3, CS2, 50 °C, HCl; (vii) CuBr2, AcOEt, CHCl3, 60 °C; (viii) CH3OH, 66 °C; (ix) paraformaldehyde, dimethylamine hydrochloride, 100–150 °C; (x) 10% NaHCO3, 85 °C,
HCl; (xi) NH3 (g), DCC, rt.
compounds 5 were synthesized by this method. Another method to
obtain 5 was that ammonia gas was passed into the solution of
compounds 10 in tetrahydrofuran for 24 h at room temperature
in the presence of DCC. Compounds 5 with dichloro-substituted
benzene ring were synthesized using this method. The key inter-
mediates 7 were synthesized from the corresponding substituted
methyl ketones 6 by refluxing for 5–12 h together with copper bro-
mide in ethyl acetate and chloroform. The thiazoles 8 were ob-
tained by refluxing the mixture of compounds 5 and compounds
7 in anhydrous methanol for 24 h.18 Then compounds 8 reacted
with paraformaldehyde and dimethylamine hydrochloride in the
presence of a catalytic amount of acetic acid to give Mannich com-
pounds which were then converted to target compounds 9 under
alkaline condition via an elimination reaction.15
benzene ring, had significantly decreased abilities of inhibiting
GSTpi activity. The inhibitory effects of compounds 9m–9o, which
have a deleted chlorine at R1 and a substituted benzene ring, on
GSTpi activity were similar to that of EA, but were weaker than
that of 9b. Compared 9m–9o with 9j–9l, it was inferred that com-
pounds with methyl group at R3 position were much more efficient
than those with ethyl substitute at R3 in inhibiting GSTpi activity.
The antiproliferative activity of these thiazole derivatives on HL-
60 cell proliferation were similar to that of our previously synthe-
sized EA oxadiazole analogues15 but were much greater than that
of the lead compound EA, suggesting that antiproliferative effects
of these compounds are independent of their inhibition on GSTpi
activity. Some compounds with weaker inhibition on GSTpi activ-
ity exhibited improved antiproliferative activity, such as 9j and
9k. These data revealed that (1) compounds with R3-methyl were
much more efficient than those with R3-ethyl in inhibiting GSTpi
activity; (2) compounds with larger substituents, such as 4-NO2
phenyl, 2-naphthyl or 4-CF3 phenyl on thiazole showed decreased
ability to inhibit GSTpi activity compared to those compounds with
phenyl at the same position; (3) EA thiazole derivatives had im-
proved antiproliferative ability over EA but that is not correlated
with their inhibitory effects on GSTpi activity; (4) EA thiazole
derivatives with R3-methyl and R4-phenyl had much greater inhib-
itory effects on the GSTpi activity. Compounds 9a–9c may repre-
2.2. The inhibition of EA thiazole derivatives on GSTpi activity
and HL-60 cell proliferation
Table 1 showed the structures of EA analogues containing a het-
erocyclic thiazole and the inhibition of each compound on GSTpi
activity as well as on HL-60 cell proliferation. The inhibitory effects
of these compounds on GSTpi activity of HL-60 cell lysates were
determined in vitro as we reported previously.17 The cell growth
inhibitory effects of these compounds were determined by count-
ing cell number treated with a variety of concentrations of each
compounds and the concentration inhibiting half of the cell prolif-
eration (GI50) was calculated.
sent
a new group of GSTpi inhibitors with antiproliferative
activity in leukemia cells and are worthy of further study.
3. Experimental
From the results shown in Table 1, it was found that 9a–9c
exhibited much more potent inhibition than EA on the GSTpi activ-
ity. The inhibition rate of GSTpi activity of EA was 65.1% at the con-
Unless otherwise noted, all materials were obtained from com-
mercial suppliers and used without further purification. All melt-
ing points were determined on a Büchi capillary melting point
apparatus and were uncorrected. The infrared (IR) spectra were
measured on KBr pellets using a Nicolet Nexus 470FT-IR spectrom-
eter and were expressed in cmÀ1. The proton nuclear magnetic res-
onance (1H NMR) spectra were recorded with a Bruker Avance
DRX600 instrument with tetramethyl-silane (TMS) as the internal
centration of 5
73.1%, 44.0% at the concentration of 1
l
M, while the inhibition rates of 9a–9c were 54.1%,
M, respectively. All 9a–9c
l
had a phenyl substituted thiazole, a middle aromatic ring with
one or double substituents and a R3-methyl. Among the three com-
pounds 9b was the most active in inhibiting GSTpi activity, which
has a chlorine-substituted aromatic ring as EA has. Compared to
9a, compounds 9g and 9i, which only have a different substituted

2318
T. Li et al. / Bioorg. Med. Chem. 20 (2012) 2316–2322
Table 1
The structures of targeting compounds and their inhibitory effects on GSTpi activities
R2
R1
R4
CH2
N
R3
C
C
OCH2
S
O
Code
R1
R2
R3
R4
GSTpi activity inhibition (%, 5
l
M)a
GSTpi activity inhibition (%, 1
l
M)b
GI50 (l
M) for HL-60c
EA
9a
9b
9c
9d
9e
9f
9g
9h
9i
9j
9k
9l
9m
9n
9o
9p
9q
9r
Cl
CH3
H
Cl
CH3
Cl
CH2CH3
CH3
CH3
—
Phenyl
Phenyl
Phenyl
65.1
100
100
100
4.4
24.2
54.1
73.1
44.0
—
—
—
—
—
—
—
—
—
—
—
—
—
44.2
3.4
6.4
4.7
3.6
2.0
1.5
5.1
2.3
3.1
0.8
0.9
2.0
5.9
2.9
1.4
1.0
3.6
1.6
H
CH3
CH3
CH3
CH3
CH3
CH3
CH3
Cl
Cl
Cl
Cl
Cl
CH3
CH3
CH3
CH3
CH3
CH3
CH3
H
H
H
H
H
CH2CH3
CH2CH3
CH2CH3
CH3
CH3
CH3
CH2CH3
CH2CH3
CH2CH3
CH3
CH3
CH3
4-NO2 Phenyl
2-Naphthyl
4-CF3 Phenyl
4-NO2 Phenyl
2-Naphthyl
4-CF3 Phenyl
4-NO2 Phenyl
2-Naphthyl
4-CF3 Phenyl
4-NO2 Phenyl
2-Naphthyl
4-CF3 Phenyl
4-NO2 Phenyl
2-Naphthyl
4-CF3 Phenyl
0
0
17.2
11.3
3.6
10.2
9.5
19.7
86.7
55.2
72.3
8.1
H
Cl
Cl
Cl
Cl
Cl
Cl
Cl
CH2CH3
CH2CH3
CH2CH3
4.3
22.2
—
—
a
The inhibition rates of GSTpi were calculated by the value of control group minus the value of treated group divided by the value of control group and multiplying by 100
at the concentration of 5 M. Each group had triplicate samples.
The inhibition rates of GSTpi were tested at the concentration of 1
l
b
l
M. Each group had triplicate samples.
c
GI50 is the concentration that inhibits 50% of proliferation compared to untreated cells.
standard. The chemical shifts (d) were reported in parts per million
(ppm) and were relative to the central peak of the solvent, which
was DMSO-d6 or CDCl3. Coupling constants (J) were given in Hz.
Data were reported as follows: chemical shift, multiplicity (s = sin-
glet, d = doublet, t = triplet, q = quartet, br = broad, m = multiplet),
coupling constants, and number of protons. Mass spectra (MS)
were measured with an API 4000 and the high resolution mass
spectra data were obtained using an Accela UPLC-LTQ Orbitrap
Mass Spectrometer. Column chromatography was carried out in
the solvents indicated with silica gel. Petroleum ether used for col-
umn chromatography had a boiling range of 60–90 °C.
7.41 (s, 1H), 7.32 (t, J = 7.20 Hz, 1H), 7.01–7.03 (m, 2H), 6.92–6.94
(m, 1H), 4.46 (s, 2H). MS (calcd/found) [M+H]+: 185.61/185.3.
Compound 3c: 2-(3-methylphenoxy)acetamide, white crystal-
line solid, yield 56.9%, 1H NMR (DMSO-d6) d (ppm): 7.48 (s, 1H),
7.38 (s, 1H), 7.16 (t, J = 8.40 Hz, 1H), 6.77–6.78(m, 2H), 6.73 (d,
J = 9.00 Hz, 1H), 4.38 (s, 2H), 2.27 (s, 3H). MS (calcd/found)
[M+H]+: 165.19/166.4.
3.2. Synthesis of the compound 11 series
Compounds 10 were synthesized via methods reported previ-
ously.17 Tetrahydrofuran (40 mL) was added to the mixture of
compounds 10 (20 mmol) and DCC (6.18 g, 30 mmol). After mixing
well, amount of ammonia gas was passed into the mixture for 24 h
at room temperature. After filtration the filter cake was washed
with tetrahydrofuran and the filtrate was collected. The crude
product was obtained with the solvent evaporating and purified
by column chromatography. The eluent was ethyl acetate/petro-
leum ether (1:2).
Compound 11: 2-(4-butyryl-2,3-dichlorophenoxy)acetamide,
white powder, yield 69.9%, mp 95–96 °C. 1H NMR (DMSO-d6) d:
7.65 (d, J = 9.00 Hz, 1H), 7.47 (s, 1H), 7.45 (s, 1H), 7.07 (d,
J = 9.00 Hz, 1H), 4.73 (s, 2H), 2.91 (t, J = 7.20 Hz, 2H), 1.56–1.60
(m, 2H), 0.90 (t, J = 7.20 Hz, 3H). MS (calcd/found) [M]+: 290.14/
290.2.
3.1. Synthesis of the compound 3 series
The intermediates 2 were synthesized via methods reported
previously.17 Compounds
2 (20 mmol) and thionyl chloride
(15 mL, 200 mmol) were added to a 50 mL round-bottomed flask,
the mixture was refluxed for 4 h, and then thionyl chloride was
evaporated at reduced pressure. Anhydrous toluene (10 mL) was
added to the acyl chloride, and the yielded solution was added
dropwise to aqueous ammonia (10 mL) in a 100 mL three-necked
flask equipped with a drying tube at 0–5 °C. The mixture was stirred
at that temperature for another 1.5 h. After filtration the solvent
was removed, the remaining residue was solved in hot acetone,
the insoluble was discarded. Crude product was obtained by evap-
orating the solvent and purified by recrystallization from ethanol–
water to obtain compounds 3.
3.3. Synthesis of the compound 4 series
Compound 3a: 2-(2,3-dimethylphenoxy)acetamide, white crys-
talline solid, yield 74.6%. 1H NMR (DMSO-d6) d (ppm): 7.34 (s, 1H),
7.35 (s, 1H), 7.01 (t, J = 8.40 Hz, 1H), 6.78 (d, J = 7.80 Hz, 1H), 6.67
(d, J = 8.40 Hz, 1H), 4.39 (s, 2H,), 2.21 (s, 3H), 2.13 (s, 3H). MS
(calcd/found) [M+H]+: 180.09/180.9.
Compounds 3 (20 mmol) were dissolved in tetrahydrofuran
(5 mL) in a 50 mL flask, then the solution was heated up to 50 °C
slowly, phosphorus pentasulfide (40 mmol) was added in batches
and stirred for 1.5 h at the same temperature. After cooling to room
temperature, the reaction solution was poured to a beaker with
100 mL mixture of ice-cold water standing for another 2 h. And
then it was extracted with ethyl acetate for 3 times, the organic
Compound 3b: 2-(3-chlorophenoxy)acetamide, white crystal-
line solid, yield 45.7%. 1H NMR (DMSO-d6) d (ppm): 7.56 (s, 1H),

T. Li et al. / Bioorg. Med. Chem. 20 (2012) 2316–2322
2319
phase was evaporated to obtain the crude product. Compounds 4
were yielded by dissolving the crude product in hot ethyl acetate,
filtering while hot, and the solvent evaporating at reduced
pressure.
Method B: compounds 11 and tetrahydrofuran (5 mL) were
added to a 50 mL flask, and the next steps were same with the syn-
thesis of the compound 4 series mentioned above.
Compound 5f: 2-[2, 3-dichloro-4-(1-oxo-butyl) phenoxy] eth-
anethioamide, white solid, yield 85.6%, mp 135–137 °C. 1H NMR
(DMSO-d6) d: 10.08 (s, 1H), 9.21 (s, 1H), 7.65 (d, J = 9.00 Hz, 1H),
7.03 (d, J = 9.00 Hz, 1H), 5.01 (s, 2H), 2.88 (t, J = 7.20 Hz, 2H), 1.55
(m, 2H), 0.91 (t, J = 1.20 Hz, 3H). MS (calcd/found) [M+H]+:
306.21/306.4.
Compound 4a: 2-(2,3-dimethylphenoxy)ethanethioamide,
white crystalline solid, yield 94.3%, mp 109–111 °C. 1H NMR
(DMSO-d6) d (ppm): 10.00 (s, 1H), 9.17 (s, 1H), 7.01 (t, J = 7.80 Hz,
1H), 6.80 (d, J = 7.80 Hz, 1H), 6.64 (d, J = 8.40 Hz, 1H), 4.71 (s, 2H),
2.22 (s, 3H), 2.15 (s, 3H). MS (calcd/found) [M+H]+: 196.07/196.3.
Compound 4b: 2-(3-chlorophenoxy)ethanethioamide, white
crystalline solid, yield 75.5%, mp 119–122 °C. 1H NMR (DMSO-d6)
d (ppm): 10.04 (s, 1H), 9.40 (s, 1H), 7.33 (t, J = 8.40 Hz, 1H), 7.03–
7.06 (m, 2H), 7.01 (dd, J1 = 2.40 Hz, J2 = 7.80 Hz, 1H), 4.79 (s, 2H).
MS (calcd/found) [M+H]+: 202.00/202.2.
Compound 4c: 2-(m-tolyloxy)ethanethioamide, white crystal-
line solid, yield 95.6%. 1H NMR (DMSO-d6) d (ppm): 9.97 (s, 1H),
9.30 (s, 1H), 7.14 (t, J = 7.80 Hz, 1H), 6.75–6.77 (m, 2H), 6.72 (dd,
J1 = 7.80 Hz, J2 = 2.40 Hz, 1H), 4.69 (s, 2H), 2.41 (s, 3H). MS (calcd/
found) [M+H]+: 182.06/182.3.
3.5. Synthesis of the compound 7 series
To a solution of substituted methyl ketones (6, 20 mmol) in
ethyl acetate (15 mL) and chloroform (15 mL), copper bromide
(8.92 g, 40 mmol) was added in batches and it was slowly heated
to 60 °C for 5–12 h, filtered while hot, the filtrate was washed with
10% hydrochloric acid (30 mL Â 3) and water (30 mL Â 3), dried
with anhydrous sodium sulfate. After filtration the solvent was
evaporated at reduced pressure and the compounds 7 were recrys-
tallized from ethanol.
3.4. Synthesis of the compound 5 series
3.6. Synthesis of the compound 8 series
Method A: carbon disulfide (30 mL) was added to compounds 4
in a three-necked flask and anhydrous aluminum chloride (4.0 g,
30 mmol) was added in batches at room temperature. A constant
pressure dropping funnel was used to add propionyl chloride or
butyryl chloride (15 mmol) dropwise to the mixture to yield vis-
cous material after stirring for 0.5 h, then it was heated to 50 °C
slowly and refluxed for 4 h, cooled to room temperature and the
supernatant fluid was decanted. Amount of ice-cold water was
added to the flask at 0 °C to yield yellow viscous solid which was
extracted with ethyl acetate. The solvent of organic layer was evap-
orating at reduced pressure to yield the crude product which was
purified by flash chromatography with ethyl acetate /petroleum
ether (1:3) to give 5.
An equimolar mixture of the compounds 5 (10 mmol) and com-
pounds 7 (10 mmol) in anhydrous methanol was refluxed for 24 h.
The mass was cooled to room temperature, the solid obtained was
filtered and dried.18
Compound 8a: 2-[2,3-dimethyl-4-(1-oxo-propyl)phenoxy-
methyl]-4-phenylthiazole, yellowish solid, yield 53.4%, mp 81–
83 °C. 1H NMR (DMSO-d6) d: 8.17 (s, 1H), 7.98 (d, J = 7.80 Hz, 2H),
7.57 (d, J = 8.40 Hz, 1H), 7.46 (t, J = 7.80 Hz, 2H), 7.36 (t,
J = 7.80 Hz ,1H), 7.06 (d, J = 8.40 Hz, 1H), 5.57 (s, 2H), 2.88 (q,
J = 7.20 Hz, 2H), 2.28 (s, 3H), 2.22(s, 3H), 1.04 (t, J = 7.20 Hz, 3H).
HRMS (ESI) m/z for C21H22NO2S [M+H]+: calculated 352.1366 found
352.1391.
Compound 5a: 2-[2,3-dimethyl-4-(1-oxo-propyl)phenoxy]eth-
anethioamide, yellowish solid, yield 51.8%, mp 139–141 °C. 1H
NMR (DMSO-d6) d: 10.02 (s, 1H), 9.21 (s, 1H), 7.53 (d, J = 8.40 Hz,
1H), 6.71 (d, J = 8.40 Hz, 1H), 4.81 (s, 2H), 2.86 (q, J = 7.80 Hz,
2H), 2.26 (s, 3H), 2.19 (s, 3H), 1.03 (t, J = 7.80 Hz, 3H). MS (calcd/
found) [M+H]+: 252.10/252.4.
Compound 5b: 2-[3-chloro-4-(1-oxo-propyl)phenoxy]ethan-
ethioamide, white solid, yield 36.6%, mp 116–119 °C. 1H NMR
(DMSO-d6) d: 10.05 (s, 1H), 9.43 (s, 1H), 7.73 (d, J = 9.00 Hz, 1H),
7.13 (d, J = 1.80 Hz, 1H), 7.02 (dd, J1 = 8.40 Hz, J2 = 1.80 Hz, 1H) ,
4.87 (s, 2H), 2.92 (q, J = 7.20 Hz, 2H), 1.05 (t, J = 7.20 Hz, 3H). MS
(calcd/found) [M+H]+: 257.74/258.2.
Compound 5c: 2-[3-methyl-4-(1-oxo-propyl)phenoxy]ethan-
ethioamide, yellow solid, yield 51.5%, 1H NMR (DMSO-d6) d:
10.04 (s, 1H), 9.40 (s, 1H), 7.84 (d, J = 8.40 Hz, 1H), 6.89 (s, 1H),
6.87 (d, J = 7.20 Hz , 1H), 4.82 (s, 2H), 2.91 (q, J = 7.20 Hz, 2H),
2.42 (s, 3H), 1.04 (t, J = 7.20 Hz, 3H). MS (calcd/found) [M+H]+:
238.08/238.2.
Compound 5d: 2-[2,3-dimethyl-4-(1-oxo-butyl)phenoxy] eth-
anethioamide, yellowish solid, yield 73.5%, mp 147–149 °C. 1H
NMR (DMSO-d6) d: 10.02 (s, 1H), 9.21 (s, 1H), 7.52 (d, J = 8.40 Hz,
1H), 6.72 (d, J = 8.40 Hz, 1H), 4.81 (s, 2H), 2.82 (t, J = 7.20 Hz, 2H),
2.26 (s, 3H), 2.19 (s, 3H), 1.55–1.59 (m, 2H), 0.89 (t, J = 7.20 Hz,
3H). MS (calcd/found) [M+H]+: 265.37/266.4.
Compound 8b: 2-[3-chloro-4-(1-oxo-propyl)phenoxymethyl]-
4-phenylthiazole, yellow solid, yield 48.1%. 1H NMR (DMSO-d6) d:
8.19 (s, 1H), 7.97 (d, J = 7.20 Hz ,2H), 7.74 (d, J = 9.00 Hz, 1H),
7.46 (t, J = 7.80 Hz, 2H), 7.36 (t, J = 7.80 Hz ,1H), 7.32 (d,
J = 2.40 Hz ,1H), 7.17 (dd, J = 8.40 Hz, J = 2.40 Hz, 1H), 5.62 (s, 2H),
2.93 (q, J = 7.20 Hz, 2H), 1.05 (t, J = 7.20 Hz, 3H). MS (calcd/found)
[M+H]+: 358.06/358.2.
Compound 8c: 2-[3-methyl-4-(1-oxo-propyl)phenoxymethyl]-
4-phenylthiazole, yellow solid, yield 27.4%. 1H NMR (DMSO-d6) d:
8.17 (s, 1H), 7.97 (d, J = 7.80 Hz ,2H), 7.86 (d, J = 9.00 Hz, 1H),
7.46 (t, J = 7.80 Hz, 2H), 7.36 (t, J = 7.20 Hz ,1H), 7.02 (d,
J = 7.20 Hz, 2H), 5.58 (s, 2H), 2.92 (q, J = 7.20 Hz, 2H), 2.44 (s, 3H),
1.04 (t, J = 7.20 Hz, 3H). MS (calcd/found) [M+H]+: 338.11/338.5.
Compound
8d:
2-[2,3-dimethyl-4-(1-oxo-butyl)phenoxy-
methyl]-4-(4-nitrophenyl)thiazole, yellowish solid, yield 67.6%,
mp 155–156 °C. 1H NMR (DMSO-d6) d: 8.54 (s, 1H), 8.33 (d,
J = 9.60 Hz, 2H), 8.25 (d, J = 9.00 Hz, 2H), 7.57 (d, J = 9.00 Hz, 1H),
7.07 (d, J = 9.00 Hz, 1H), 5.60 (s, 2H), 2.84 (t, J = 7.20 Hz, 2H), 2.28
(s, 3H), 2.23 (s, 3H), 1.56–1.60 (m, 2H), 0.90 (t, J = 7.20 Hz, 3H).
MS (calcd/found) [M+H]+: 410.39/411.4.
Compound
8e:
2-[2,3-dimethyl-4-(1-oxo-butyl)phenoxy-
methyl]-4-(naphthalen-2-yl)thiazole, yellowish solid, yield 68.9%,
mp 119–122 °C. 1H NMR (DMSO-d6) d: 8.55 (s, 1H), 8.32 (s, 1H),
8.12 (dd, J1 = 8.40 Hz, J2 = 1.20 Hz, 1H), 7.99–8.02 (m, 2H), 7.94
(d, J = 7.80 Hz, 1H), 7.52–7.59 (m, 3H), 7.09 (d, J = 8.40 Hz, 1H),
5.61 (s, 2H), 2.85 (t, J = 7.20 Hz, 2H), 2.29 (s, 3H), 2.24 (s, 3H),
1.57–1.61 (m, 2H), 0.90 (t, J = 7.20 Hz, 3H). MS (calcd/found)
[M+H]+: 415.55/416.5.
Compound 5e: 2-[3-chloro-4-(1-oxo-butyl)phenoxy]ethanethi-
oamide, white solid, yield 54.6%, mp 115–117 °C. 1H NMR
(DMSO-d6) d: 10.05 (s, 1H), 9.43 (s, 1H), 7.71 (d, J = 8.40 Hz, 1H),
7.13 (d, J = 3.00 Hz, 1H), 7.02 (dd, J1 = 9.00 Hz, J2 = 2.4 Hz, 1H),
4.87 (s, 2H), 2.89 (t, J = 7.20 Hz, 2H), 1.57–1.61 (m, 2H), 0.90 (t,
J = 7.20 Hz, 3H). MS (calcd/found) [M+H]+: 271.76/272.4.
Compound
8f:
2-[2,3-dimethyl-4-(1-oxo-butyl)phenoxy-
methyl]-4-(4-trifluoromethylphenyl)thiazole, white solid, yield

2320
T. Li et al. / Bioorg. Med. Chem. 20 (2012) 2316–2322
68.5%, mp 114–117 °C. 1H NMR (DMSO-d6) d: 8.42 (s, 1H), 8.20 (d,
J = 7.80 Hz, 2H), 7.83 (d, J = 7.80 Hz, 2H), 7.56 (d, J = 8.40 Hz, 1H),
7.067 (d, J = 8.40 Hz, 1H), 5.60 (s, 2H), 2.84 (t, J = 7.2 Hz, 2H), 2.28
(s, 3H), 2.23 (s, 3H), 1.56–1.60 (m, 2H), 0.90 (t, J = 7.20 Hz, 3H).
MS (calcd/found) [M+H]+: 433.49/434.4.
88–90 °C. 1H NMR (DMSO-d6) d: 8.43 (s, 1H), 8.20 (d, J = 7.80 Hz,
2H), 7.83 (d, J = 7.80 Hz, 2H), 7.75 (d, J = 8.40 Hz, 1H), 7.32 (d,
J = 2.40 Hz, 1H), 7.17 (dd, J1 = 8.40 Hz, J1 = 2.40 Hz, 1H), 5.65 (s,
2H), 2.93 (q, J = 7.20 Hz, 2H), 1.06 (t, J = 7.20 Hz, 3H). MS (calcd/
found) [M+H]+: 425.85/426.2.
Compound 8g: 2-[2,3-dimethyl-4-(1-oxo-propyl)phenoxy-
methyl]-4-(4-nitrophenyl) thiazole, white powder, yield 65.6%,
mp 144–147 °C. 1H NMR (DMSO-d6) d: 8.54 (s, 1H), 8.33 (d,
J = 9.60 Hz, 2H), 8.26 (d, J = 9.00 Hz, 2H), 7.57 (d, J = 9.00 Hz, 1H),
7.06 (d, J = 9.00 Hz, 1H), 5.60 (s, 2H), 2.88 (q, J = 7.20 Hz, 2H),
2.28 (s, 3H), 2.23 (s, 3H), 1.04 (t, J = 7.20 Hz, 3H). MS (calcd/found)
[M+H]+:396.46/397.4.
Compound
8p:
2-[2,3-dichloro-4-(1-oxo-butyl)phenoxy-
methyl]-4-(4-nitrophenyl)thiazole, yellow solid, yield 62.7%, mp
174–176 °C. 1H NMR (DMSO-d6) d: 8.57 (s, 1H), 8.33 (d,
J = 8.40 Hz, 2H), 8.25 (d, J = 9.00 Hz, 2H), 7.72 (d, J = 9.00 Hz, 1H),
7.45 (d, J = 8.40 Hz, 1H), 5.76 (s, 2H), 2.92 (t, J = 3.60 Hz, 2H), 1.60
(m, 2H), 0.91 (t, J = 7.20 Hz, 3H). MS (calcd/found) [M+H]+:
451.32/451.2.
Compound 8h: 2-[2,3-dimethyl-4-(1-oxo-propyl)phenoxy-
methyl]-4-(naphthalen-2-yl)thiazole, yellowish powder, yield
56.0%, mp 107–109 °C. 1H NMR (DMSO-d6) d: 8.55 (s, 1H), 8.32
(s, 1H), 8.12 (dd, J1 = 9.00 Hz, J1 = 1.80 Hz, 1H), 7.99–8.02 (m, 2H),
7.94 (d, J = 7.80 Hz, 1H), 7.58 (d, J = 8.40 Hz, 1H), 7.55 (m, 2H),
7.09 (d, J = 9.00 Hz, 1H), 5.61 (s, 2H), 2.88 (q, J = 7.20 Hz, 2H),
2.28 (s, 3H), 2.24 (s, 3H), 1.05 (t, J = 7.20 Hz, 3H). MS (calcd/found)
[M+H]+:401.52/402.4.
Compound
8q:
2-[2,3-dichloro-4-(1-oxo-butyl)phenoxy-
methyl]-4-(naphthalen-2-yl)thiazole, white powder, yield 58.3%,
mp 135–137 °C. 1H NMR (DMSO-d6) d: 8.45 (s, 1H), 7.97 (dd,
J1 = 7.20 Hz, J2 = 1.20 Hz, 1H), 7.90–7.93(m, 2H), 7.86 (d,
J = 6.60 Hz, 1H), 7.67 (s, 1H), 7.65 (s, 1H), 7.48–7.53 (m, 2H), 7.23
(s, 1H), 5.56 (s, 2H), 2.92 (t, J = 7.20 Hz, 2H), 1.70–1.76 (m, 2H),
0.98 (t, J = 7.20 Hz, 3H). MS (calcd/found) [M]+: 456.38/456.0729.
Compound
8r:
2-[2,3-dichloro-4-(1-oxo-butyl)phenoxy-
Compound
8i:
2-[2,3-dimethyl-4-(1-oxo-propyl)phenoxy-
methyl]-4-(4-trifluoromethylphenyl)thiazole, white solid, yield
58.5%, mp 88–90 °C. 1H NMR (DMSO-d6) d: 8.01 (d, J = 7.80 Hz,
2H), 7.69 (d, J = 8.40 Hz, 2H), 7.65 (s, 1H), 7.38 (d, J = 8.40 Hz,
1H), 7.04 (d, J = 8.40 Hz, 1H), 5.53 (s, 2H), 2.91 (t, J = 7.20 Hz, 2H),
1.72 (m, 2H), 0.98 (t, J = 7.20 Hz, 3H). MS (calcd/found) [M]+:
474.32/474.0307.
methyl]-4-(4-trifluoromethylphenyl)thiazole, yellow solid, yield
58.5%, mp 107–110 °C. 1H NMR (DMSO-d6) d: 8.41 (s, 1H), 8.20
(d, J = 8.40 Hz, 2H), 7.83 (d, J = 8.40 Hz, 2H), 7.57 (d, J = 8.40 Hz,
1H), 7.06 (d, J = 9.00 Hz, 1H), 5.59 (s, 2H), 2.88 (q, J = 7.2 Hz, 2H),
2.28 (s, 3H), 2.23 (s, 3H), 1.04 (t, J = 7.20 Hz, 3H). MS (calcd/found)
[M+H]+: 419.46/420.4.
Compound 8j: 2-[3-chloro-4-(1-oxo-butyl)phenoxymethyl]-4-
(4-nitrophenyl) thiazole, yellow solid, yield 68.2%, mp 149–
151 °C. 1H NMR (DMSO-d6) d: 8.56 (s, 1H), 8.33 (d, J = 9.00 Hz,
2H), 8.25 (d, J = 9.00 Hz, 2H), 7.73 (d, J = 9.00 Hz, 1H), 7.32 (d,
J = 2.40 Hz, 1H), 7.17 (dd, J1 = 8.40 Hz, J2 = 2.40 Hz, 1H), 5.65 (s,
2H), 2.89 (t, J = 7.20 Hz, 2H), 1.57–1.61 (m, 2H), 0.90 (t,
J = 7.80 Hz, 3H). MS (calcd/found) [M+H]+:416.88/417.4.
Compound 8k: 2-[3-chloro-4-(1-oxo-butyl)phenoxymethyl]-4-
(naphthalen-2-yl)thiazole, white solid, yield 69.5%, mp 88–90 °C.
1H NMR (DMSO-d6) d: 8.55 (s, 1H), 8.34 (s, 1H), 8.12 (dd,
J1 = 9.00 Hz, J2 = 1.80 Hz, 1H), 7.99–8.01 (m, 2H), 7.94 (d,
J = 7.20 Hz, 1H), 7.74 (d, J = 8.40 Hz, 1H), 7.52–7.57 (m, 2H), 7.35
(d, J = 3.00 Hz, 1H), 7.19 (dd, J1 = 8.40 Hz, J2 = 2.40 Hz , 1H), 5.67
(s, 2H), 2.90 (t, J = 7.20 Hz, 2H), 1.56–1.63 (m, 2H), 0.91 (t,
J = 7.20 Hz, 3H). MS (calcd/found) [M+H]+: 421.94/422.3.
Compound 8l: 2-[3-chloro-4-(1-oxo-butyl)phenoxymethyl]-4-
(4-trifluoromethylphenyl)thiazole, white solid, yield 67.6%, mp
86–88 °C. 1H NMR (DMSO-d6) d: 8.43 (s, 1H), 8.20 (d, J = 8.40 Hz,
2H), 7.83 (d, J = 8.40 Hz, 2H), 7.73 (d, J = 8.40 Hz, 1H), 7.32 (d,
J = 2.40 Hz, 1H), 7.17 (dd, J1 = 8.40 Hz, J2 = 2.40 Hz, 1H), 5.64 (s,
2H), 2.90 (t, J = 7.20 Hz, 2H), 1.57–1.61 (m, 2H), 0.90 (t,
J = 7.20 Hz, 3H). MS (calcd/found) [M+H]+: 439.88/440.4.
Compound 8m: 2-[3-chloro-4-(1-oxo-propyl)phenoxymethyl]-
4-(4-nitrophenyl)thiazole, yellow powder, yield 69.6%, mp 148–
150 °C. 1H NMR (DMSO-d6) d: 8.56 (s, 1H), 8.33 (d, J = 8.40 Hz,
2H), 8.25 (d, J = 9.00 Hz, 2H), 7.75 (d, J = 8.40 Hz, 1H), 7.32 (d,
J = 2.40 Hz, 1H), 7.17 (dd, J1 = 9.00 Hz, J2 = 2.40 Hz, 1H), 5.66 (s,
2H), 2.93 (q, J = 7.20 Hz, 2H), 1.05 (t, J = 7.20 Hz, 3H). MS (calcd/
found) [M+H]+:402.85/403.4.
3.7. Synthesis of the compound 9 series
In a 50 mL round-bottomed flask a mixture of compounds 8
(9.6 mmol), paraformaldehyde (0.38 g, 11.5 mmol), dimethylamine
hydrochloride (0.91 g, 10.4 mmol) and acetic acid (0.05 mL) was
heated to 100 °C for about 1.5 h, during which period suction
was applied. When the mixture was cooled to room temperature,
the obtained Mannich compounds were dissolved in 10% sodium
bicarbonate and modulated to slight alkalinity. The resulting solu-
tion was heated to 85 °C for 40 min and extracted with ethyl ace-
tate, the solvent of organic layer was evaporated at reduced
pressure to yield oil. The target compounds 9 were obtained by col-
umn chromatography, the eluent was acetone/petroleum ether
(1:20).
Compound 9a: 2-[2,3-dimethyl-4-(2-methylene-1-oxo-propyl)
phenoxymethyl]-4-phenylthiazole, white powder, yield 39.5%,
mp 69–70 °C. 1H NMR (CDCl3-d3) d: 7.90 (d, J = 7.80 Hz, 2H), 7.51
(s, 1H), 7.44 (t, J = 7.80 Hz, 2H), 7.35 (t, J = 7.80 Hz, 1H), 7.09 (d,
J = 7.80 Hz ,1H), 6.81 (d, J = 7.80 Hz, 1H), 5.92 (s, 1H), 5.57 (s, 1H),
5.45 (s, 2H), 2.29 (s, 3H), 2.21 (s, 3H), 2.04 (s, 3H). IR (KBr, cmÀ1
)
:
m@CH: 3113.78, 3068.66, 3025.33; mCH: 2976.26, 2922.56; mC@O
1653.48;
1324.59;
741.60. HRMS (ESI) m/z for
m
m
C@C: 1624.97, 1589.43, 1516.50; dCH: 1444.25, 1357.02,
C–O: 1266.54, 1230.89; @CH: 1090.84, 947.82, 803.22,
22H22NO2S [M+H]+: calculated
c
C
364.1366 found 364.1381.
Compound 9b: 2-[3-chloro-4-(2-methylene-1-oxo-propyl) phe-
noxymethyl]-4-phenylthiazole, yield 75.0%, mp 138–139 °C. 1H
NMR (DMSO-d6) d: 8.20 (s, 1H), 7.97 (d, J = 7.80 Hz, 2H), 7.46
(t, J = 7.80 Hz, 2H), 7.39 (d, J = 8.40 Hz, 1H), 7.36 (t, J = 7.20 Hz ,1H),
7.34 (dd, J 1 = 7.80 Hz, J2 = 2.40 Hz, 1H), 7.15–7.18 (m, 1H), 6.12
Compound 8n: 2-[3-chloro-4-(1-oxo-propyl)phenoxymethyl]-
4-(naphthalen-2-yl)thiazole, light red powder, yield 50.0%, mp
109–111 °C. 1H NMR (DMSO-d6) d: 8.55 (s, 1H), 8.34 (s, 1H), 8.11
(dd, J1 = 8.40 Hz, J2 = 1.80 Hz, 1H), 7.99–8.01 (m, 2H), 7.94 (d,
J = 7.20 Hz, 1H), 7.76 (d, J = 9.00 Hz, 1H), 7.55 (m, 2H), 7.35 (d,
J = 2.40 Hz, 1H), 7.19 (dd, J1 = 8.40 Hz, J2 = 2.40 Hz, 1H), 5.67 (s,
2H), 2.93 (q, J = 7.20 Hz, 2H), 1.06 (t, J = 7.20 Hz, 3H). MS (calcd/
found) [M+H]+:407.91/408.4.
(s, 1H), 5.61 (s, 1H), 5.52 (s, 2H), 1.95 (s, 3H). IR (KBr, cmÀ1
)
:
m@CH: 3099.94, 3070.24; mCH: 2976.32, 2922.48, 2880.86; mC@O
1650.91;
mC@C: 1598.16, 1559.57, 1507.16, 1495.80; dCH: 1470.24,
1456.71, 1445.02, 1369.65, 1335.97, 1298.32;
m
C–O:1243.95,
1230.95;
c
@CH: 1061.94, 917.04, 841.17, 758.00. HRMS (ESI) m/z
for C20H17ClNO2S [M+H]+: calculated 370.0663 found 370.0676.
Compound 9c: 2-[3-methyl-4-(2-methylene-1-oxo-propyl)
phenoxymethyl]-4-phenylthiazole, white powder, yield 31.3%,
mp 129–131 °C. 1H NMR (CDCl3-d3) d: 7.91 (d, J = 7.80 Hz, 2H),
Compound 8o: 2-[3-chloro-4-(1-oxo-propyl)phenoxymethyl]-
4-(4-trifluoromethylphenyl)thiazole, white solid, yield 58.5%, mp

T. Li et al. / Bioorg. Med. Chem. 20 (2012) 2316–2322
2321
7.52 (s, 1H), 7.44 (t, J = 7.80 Hz, 2H), 7.36 (t, J = 7.20 Hz, 1H), 7.29
(d, J = 8.40 Hz ,1H), 6.91 (s, 1H), 6.85 (dd, J1 = 8.40 Hz,
J2 = 2.40 Hz, 1H), 5.91 (s, 1H), 5.55 (s, 1H), 5.47 (s, 2H), 2.34 (s,
yield 68.5%, mp 104–106 °C. 1H NMR (DMSO-d6) d: 8.42 (s, 1H),
8.20 (d, J = 8.40 Hz, 2H), 7.83 (d, J = 8.40 Hz, 2H), 7.11 (d,
J = 8.40 Hz, 1H), 7.06 (d, J = 9.00 Hz, 1H), 6.04 (s, 1H), 5.57 (s, 2H),
5.48 (s, 1H), 2.23 (s, 3H), 2.13 (s, 3H), 1.96 (s, 3H). IR (KBr, cmÀ1):
3H), 2.04 (s, 3H). IR (KBr, cmÀ1
)
m
:
@CH: 3095.89, 3059.71; mCH
1633.70; mC@C 1599.79,
1508.37; dCH: 1445.40, 1367.85, 1336.32, 1309.41; C–O:1248.35,
1232.96; @CH: 1011.83, 957.11, 847.16, 762.30. HRMS (ESI) m/z
:
2983.90, 2956.19, 2921.15; mC@O
:
m
m
@CH: 3116.46, 3088.72;
C@C: 1617.62, 1591.85, 1579.96, 1508.90, 1449.19; dCH: 1329.73;
1272.48; c@CH 1069.72, 854.17, 766.14. HRMS (ESI)
23H21F3NO2S [M+H]+: calculated 432.1240 found
mCH: 2919.31, 2868.88; mC@O: 1683.15;
m
c
mC–O
m/z for C
:
:
for C21H20NO2S [M+H]+: calculated 350.1209 found 350.1223.
Compound 9d: 2-[2,3-dimethyl-4-(2-methylene-1-oxo-butyl)
phenoxymethyl]-4-(4-nitrophenyl)thiazole, white solid, yield
62.3%, mp 145–152 °C. 1H NMR (DMSO-d6) d: 8.54 (s, 1H), 8.33
(d, J = 9.00 Hz, 2H), 8.25 (d, J = 9.00 Hz, 2H), 7.10 (d, J = 8.40 Hz,
1H), 7.05 (d, J = 8.40 Hz, 1H), 5.95 (s, 1H), 5.58 (s, 2H), 5.49 (s,
1H), 2.38 (q, J = 7.20 Hz, 2H), 2.23 (s, 3H), 2.14 (s, 3H), 1.07 (t,
432.1236.
Compound 9j: 2-[3-chloro-4-(2-methylene-1-oxo-butyl) phen-
oxymethyl]-4-(4-nitrophenyl)thiazole, white crystalline solid,
yield 76.9%, mp 111–112 °C. 1H NMR (DMSO-d6) d: 8.56 (s, 1H),
8.33 (d, J = 9.00 Hz, 2H), 8.25 (d, J = 9.00 Hz, 2H), 7.38 (d,
J = 8.40 Hz, 1H), 7.34 (d, J = 9.00 Hz, 1H), 7.17 (dd, J1 = 8.40 Hz,
J2 = 2.40 Hz, 1H), 6.04 (s, 1H), 5.65 (s, 2H), 5.54 (s, 1H), 2.37 (q,
J = 7.20 Hz, 3H). IR (KBr, cmÀ1):
2921.64, 2873.38; mC@O 1641.89; mC@C
1522.28, 1509.61, 1482.03; NO2: 1341.16;
m
@CH: 3121.10;
1599.36, 1578.59,
C–O: 1276.62; c@CH
mCH: 2963.22,
:
:
J = 7.2 Hz, 2H), 0.90 (t, J = 7.2 Hz, 3H). IR (KBr, cmÀ1): m@CH
3097.71; mCH 2969.51, 2935.62, 2875.13, 2851.09; mC@O
1653.84; mC@C
NO2: 1344.80;
:
:
m
m
:
:
:
1099.88, 857.00, 847.12, 744.80. HRMS (ESI) m/z for C23H23N2O4S
1599.22, 1566.07, 1522.36, 1514.60, 1492.26;
C–O: 1294.67; @CH: 1066.83, 981.27, 903.61,
[M+H]+: calculated 423.1373 found 423.1371.
m
m
c
Compound 9e: 2-[2,3-dimethyl-4-(2-methylene-1-oxo-butyl)
phenoxymethyl]-4-(naphthalen-2-yl)thiazole, white solid, yield
72.6%, mp 134–136 °C. 1H NMR (DMSO-d6) d: 8.55 (s, 1H), 8.33(s,
1H), 8.12 (dd, J1 = 8.40 Hz, J2 = 1.20 Hz, 1H), 7.99–8.02 (m, 2H),
7.94 (d, J = 7.20 Hz, 1H), 7.52–7.56 (m, 2H), 7.10 (q, J = 8.40 Hz,
2H), 5.95 (s, 1H) 5.59 (s, 2H), 5.50 (s, 1H), 2.38 (q, J = 7.20 Hz, 2H),
2.25 (s, 3H), 2.15 (s, 3H),1.07 (t, J = 7.20 Hz, 3H). IR (KBr, cmÀ1):
863.04, 844.37, 749.09. HRMS (ESI) m/z for C21H18ClN2O4S
[M+H]+: calculated 429.0670 found 429.0668.
Compound 9k: 2-[3-chloro-4-(2-methylene-1-oxo-butyl) phen-
oxymethyl]-4-(naphthalen-2-yl)thiazole, white crystalline solid,
yield 50.0%, mp 101–102 °C. 1H NMR (DMSO-d6) d: 8.55 (s, 1H),
8.35(s, 1H), 8.12 (dd, J1 = 8.40 Hz, J2 = 1.20 Hz, 1H), 7.99–8.01(m,
2H), 7.94 (d, J = 7.20 Hz, 1H),7.52–7.56 (m, 2H), 7.41 (d,
J = 9.00 Hz, 1H), 7.37 (d, J = 2.40 Hz, 1H), 7.18 (dd, J = 9.00 Hz,
J = 2.40 Hz, 1H), 6.04(s, 1H) 5.65 (s, 2H), 5.55 (s, 1H), 2.37(q,
m@CH
m
:
3103.45, 3058.86; mCH
C@O: 1651.76; C@C: 1590.94, 1519.59, 1483.20, 1445.57; dCH
1353.74; C–O: 1268.86;
:
2965.60, 2919.85, 2872.20;
m
:
m
c
@CH: 1087.32, 943.79, 802.25, 760.07.
J = 7.2 Hz, 2H), 1.07 (s, 3H). IR (KBr, cmÀ1): m@CH
3055.33; CH: 2971.25, 2935.43, 2873.26; C@O: 1664.80; mC@C
1599.45, 1559.55, 1506.87, 1490.74, 1453.91; dCH: 1356.55; mC–O
1298.58, 1236.76; c@CH
: 3108.01,
HRMS (ESI) m/z for C27H26NO2S [M+H]+: calculated 428.1679 found
428.1677.
m
m
:
:
Compound 9f: 2-[2,3-dimethyl-4-(2-methylene-1-oxo-butyl)
phenoxymethyl]-4-(4-trifluoromethylphenyl) thiazole, white so-
lid, yield 78.5%, mp 86–87 °C. 1H NMR (DMSO-d6) d: 8.42 (s, 1H),
8.20 (d, J = 7.80 Hz, 2H), 7.83 (d, J = 7.80 Hz, 2H), 7.10 (d,
J = 8.40 Hz, 1H), 7.05 (d, J = 8.40 Hz, 1H), 5.95 (s, 1H), 5.57 (s, 2H),
5.49 (s, 1H), 2.38 (q, J = 7.20 Hz, 2H), 2.23 (s, 3H), 2.14 (s, 3H),
:
1060.17, 1043.76, 979.66, 905.48,
861.42, 831.20, 773.77, 751.80. HRMS (ESI) m/z for C25H21ClNO2S
[M+H]+: calculated 434.0976 found 434.0975.
Compound 9l: 2-[3-chloro-4-(2-methylene-1-oxo-butyl) phen-
oxymethyl]-4-(4-trifluoromethylphenyl)thiazole, white solid, yield
58.5%, mp 104–106 °C. 1H NMR (DMSO-d6) d: 8.44 (s, 1H), 8.20 (d,
J = 7.80 Hz, 2H), 7.83 (d, J = 7.80 Hz, 2H), 7.73 (d, J =8.40 Hz, 1H),
7.34 (d, J = 2.40 Hz, 1H), 7.33 (dd, J1 = 8.40 Hz, J2 = 2.4 Hz, 1H),
6.04 (s, 1H), 5.64 (s, 2H), 5.54 (s, 1H), 2.37 (q, J = 7.20 Hz, 2H),
1.07 (t, J = 7.20 Hz, 3H). IR (KBr, cmÀ1):
m
@CH: 3114.66; mCH
1649.55; mC@C 1617.86,
@CH: 1069.70,
:
2966.08, 2918.55, 2874.16; mC@O
:
:
1590.25, 1508.20; dCH: 1329.14;
m
C–O: 1271.02; c
854.25, 765.93. HRMS (ESI) m/z for C24H23F3NO2S [M+H]+: calcu-
lated 446.1396 found 446.1393.
1.07 (t, J = 7.20 Hz, 3H). IR (KBr, cmÀ1):
2968.58, 2935.49, 2879.43; mC@O 1661.06; mC@C
1565.92, 1511.10, 1492.97, 1456.72; dCH: 1324.07; C–O: 1242.93;
m
@CH: 3115.44; mCH
:
:
:
1599.30,
Compound 9g: 2-[2,3-dimethyl-4-(2-methylene-1-oxo-propyl)
phenoxymethyl]-4-(4-nitrophenyl)thiazole, white powder, yield
75.6%, mp 158–160 °C. 1H NMR (DMSO-d6) d: 8.54 (s, 1H), 8.33
(d, J = 9.00 Hz, 2H), 8.25 (d, J = 9.00 Hz, 2H), 7.11 (d, J = 8.40 Hz,
1H), 7.05 (d, J = 8.40 Hz, 1H), 6.04 (s, 1H), 5.58 (s, 2H), 5.48 (s,
m
c
@CH: 1070.64, 943.38, 980.57, 909.75, 852.56, 843.13, 760.57,
733.83. HRMS (ESI) m/z for C22H18ClF3NO2S [M+H]+: calculated
452.0693 found 452.0691.
Compound 9m: 2-[3-chloro-4-(2-methylene-1-oxo-propyl)
phenoxymethyl-4-(4-nitrophenyl)thiazole, light red crystalline so-
lid, yield 76.9%, mp 88–91 °C. 1H NMR (DMSO-d6) d: 8.56 (s, 1H),
8.33 (d, J = 9.60 Hz, 2H), 8.25 (d, J = 9.00 Hz, 2H), 7.40 (d,
J = 8.40 Hz, 1H), 7.34 (d, J = 2.40 Hz, 1H), 7.17 (dd, J1 = 8.40 Hz, J1
= 2.40 Hz, 1H), 6.12 (s, 1H), 5.64 (s, 2H), 5.53 (s, 1H), 1.95 (s, 3H).
1H), 2.23 (s, 3H), 2.13 (s, 3H), 1.96 (s, 3H). IR (KBr, cmÀ1): m@CH
:
3094.47;
m
CH: 2922.45, 2848.60;
mC@O: 1653.48;
m
C@C: 1597.22,
1579.44, 1507.98, 1482.34;
m
NO2: 1336.32;
m
C–O: 1267.42; c@CH:
1088.68, 862.79, 844.75, 795.59, 753.79. HRMS (ESI) m/z for
C
22H21N2O4S [M+H]+: calculated 409.1217 found 409.1214.
Compound 9h: 2-[2,3-dimethyl-4-(2-methylene-1-oxo-propyl)
IR (KBr, cmÀ1):
1665.75; mC@C
1346.38; C–O: 1294.13;
m
@CH: 3106.73;
m
CH: 2924.34, 2850.22; mC@O
:
:
phenoxymethyl]-4-(naphthalen-2-yl)thiazole, white powder, yield
66.0%, mp 116–118 °C. 1H NMR (DMSO-d6) d: 8.55 (s, 1H), 8.32(s,
1H), 8.12 (dd, J1 = 7.2 Hz, J2 = 1.8 Hz, 1H), 7.99–8.02 (m, 2H), 7.94
(d, J = 7.20 Hz, 1H), 7.52–7.56(m, 2H), 7.12 (d, J = 8.40 Hz, 1H),
7.07 (d, J = 8.40 Hz, 1H), 6.04 (s, 1H), 5.59 (s, 2H), 5.49 (s, 1H),
: 1598.82, 1521.78, 1493.18, 1449.99; mNO2
m
c@CH: 1061.96, 918.06, 861.24, 845.77,
742.48. HRMS (ESI) m/z for C20H16ClN2O4S [M+H]+: calculated
415.0514 found 415.0511.
Compound 9n: 2-[3-chloro-4-(2-methylene-1-oxo-propyl)
phenoxymethyl]-4-(naphthalen-2-yl)thiazole, light red crystalline
solid, yield 50.0%, mp 105–107 °C. 1H NMR (DMSO-d6) d: 8.55 (s,
1H), 8.34 (s, 1H), 8.12 (dd, J1 = 8.40 Hz , J2 = 1.20 Hz, 1H), 7.99–
8.01(m, 2H), 7.94 (d, J = 7.80 Hz, 1H), 7.52–7.56 (m, 2H), 7.41 (d,
J = 8.40 Hz, 1H), 7.37 (d, J = 2.40 Hz, 1H), 7.18 (dd, J1 = 9.00 Hz,
J2 = 2.40 Hz, 1H), 6.12 (s, 1H) 5.67 (s, 2H), 5.54 (s, 1H), 1.96 (s,
2.25 (s, 3H), 2.14 (s, 3H), 1.96 (s, 3H). IR (KBr, cmÀ1): m@CH
:
3111.49, 3051.20;
m
CH: 2972.96, 2919.32, 2842.02;
C@C: 1593.12, 1584.01, 1520.90, 1484.39, 1446.79; dCH: 1354.34;
C–O: 1268.09; @CH: 1085.37, 943.38, 858.61, 808.86, 769.40,
mC@O: 1655.22;
m
m
c
761.59. HRMS (ESI) m/z for
C
26H24NO2S [M+H]+: calculated
414.1522 found 414.1520.
Compound 9i: 2-[2,3-dimethyl-4-(2-methylene-1-oxo-propyl)
phenoxymethyl]-4-(4-trifluoromethylphenyl)thiazole, white solid,
3H). IR (KBr, cmÀ1): m@CH
2982.74, 2925.09, 2865.53; mC@O
:
3114.67, 3088.31, 3055.47; mCH
:
:
1664.62; mC@C 1596.16,
:

2322
T. Li et al. / Bioorg. Med. Chem. 20 (2012) 2316–2322
1565.31, 1499.09; dCH: 1344.43;
m
C–O: 1295.92;
c
@CH: 1058.32,
measured spectrophotometrically at 25 °C using 1-cholro-2,4-dini-
trobenzene (CDNB) and GSH as substrates.17 The CDNB–GSH com-
plex has a strong absorptivity at 340 nm and the extinction
coefficient of 9.6 mMÀ1cmÀ1 was used to calculate GSTpi activity.
GSTpi activity was defined as nanomoles of product per minute
per milligram of protein. The GSTpi activity inhibition rate was cal-
culated as (Vc–Vt)/Vc  100%. Vc refers to GSTpi activity of control
group; Vt refers to GSTpi activity of treated group.
940.78, 862.87, 832.42, 753.65. HRMS (ESI) m/z for C24H19ClNO2S
[M+H]+: calculated 420.0820 found 420.0817.
Compound 9o: 2-[3-chloro-4-(2-methylene-1-oxo-propyl)
phenoxymethyl]-4-(4-trifluoromethylphenyl) thiazole, yellowish
solid, yield 58.5%, mp 87–90 °C. 1H NMR (DMSO-d6) d: 8.44 (s,
1H), 8.20 (d, J = 7.80 Hz, 2H), 7.83 (d, J = 7.80 Hz, 2H), 7.40 (d,
J = 8.40 Hz, 1H), 7.34 (d, J = 2.40 Hz, 1H), 7.17 (dd, J1 = 8.40 Hz,
J2 = 2.40 Hz, 1H), 6.12 (s, 1H) 5.63 (s, 2H), 5.53 (s, 1H), 1.95 (s,
3H). IR (KBr, cmÀ1):
1663.30; C@C: 1614.86, 1599.73, 1565.84, 1492.42; dCH: 1323.72;
C–O: 1292.58;
m@CH: 3112.45;
mCH: 2931.62, 2882.16; mC@O
:
3.9. Inhibition of HL-60 cell proliferation
m
m
c
@CH: 1070.57, 917.65, 852.17, 841.66, 759.65.
Cell proliferation inhibition was determined as we reported
previously.19 HL-60 cells were seeded in 24-well plates at a density
of 4 Â 104/mL and incubated with various concentrations of the
tested compounds for 72 h. The cell number including trypan blue
staining positive and negative cells in each group was counted. The
growth inhibition rate was calculated as (1ÀNt/Nc) Â 100%. Nt re-
fers to the cell number of the treated group, Nc refers to the cell
number of the control group. The concentration inhibiting half of
the cell proliferation (GI50) was calculated.
HRMS (ESI) m/z for C21H16ClF3NO2S [M+H]+: calculated 438.0537
found 438.0535.
Compound 9p: 2-[2,3-dichloro-4-(2-methylene-1-oxo-butyl)
phenoxymethyl]-4-(4-nitrophenyl)thiazole, yellowish solid, yield
66.7%, mp 179–182 °C. 1H NMR (DMSO-d6) d: 8.31 (d, J = 9.00 Hz,
2H), 8.08 (d, J = 9.00 Hz, 2H), 7.76 (s, 1H), 7.18 (d, J = 8.40 Hz, 1H),
7.04 (d, J = 8.40 Hz, 1H), 5.95 (s, 1H) 5.60 (s, 1H), 5.54 (s, 2H), 2.47
(q, J = 7.80 Hz, 2H), 1.15 (t, J = 7.20 Hz, 3H). IR (KBr, cmÀ1): m@CH
:
3108.52, 3081.01; mCH
m
:
2966.14, 2933.30; mC@O
C@C: 1599.08, 1585.97, 1523.99, 1466.83; NO2: 1342.94; mC–O
1065.81, 860.37, 846.13, 741.40. HRMS (ESI)
:
1663.67;
m
:
Acknowledgments
1294.13; c@CH
:
m/z for
C
21H17Cl2N2O4S [M+H]+: calculated 463.0281 found
This work was supported by Grants from the National Natural
Science Foundation of China (No. 21072115) and Shandong Natural
Science Foundation (No. ZR2011HM042).
463.0277.
Compound 9q: 2-[2,3-dichloro-4-(2-methylene-1-oxo-butyl)
phenoxymethyl]-4-(naphthalen-2-yl)thiazole, white powder, yield
58.3%, mp 135–137 °C. 1H NMR (DMSO-d6) d: 8.55 (s, 1H), 8.36 (s,
1H), 8.12 (dd, J1 = 9.00 Hz, J2 = 1.20 Hz, 1H), 7.99–8.01 (m, 2H), 7.93
(d, J = 1.80 Hz, 1H), 7.52–7.57 (m, 2H), 7.47 (d, J = 7.80 Hz, 1H), 7.65
(d, J = 7.80 Hz, 1H), 6.09 (s, 1H), 5.76 (s, 2H), 5.60 (s, 1H), 2.38 (q,
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.bmc.2012.02.011.
J = 7.20 Hz, 2H), 1.09 (t, J = 7.20 Hz, 3H). IR (KBr, cmÀ1): m@CH
3102.95, 3058.74; CH: 2968.67, 2936.43; C@O: 1658.25; mC@C
1586.82, 1517.54, 1472.29; dCH: 1384.69, 1357.99;
:
:
m
m
References and notes
m
C–O: 1292.40,
: 1068.18, 1050.99, 1001.76, 948.00, 811.25,
1. Frova, C. Biomol. Eng. 2006, 23, 149.
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1265.56; c@CH
773.01. HRMS (ESI) m/z for C25H20Cl2NO2S [M+H]+: calculated
468.0586 found 468.0583.
5. Adler, V.; Yin, Z.; Fuchs, S. Y.; Benezra, M.; Rosario, L.; Tew, K. D.; Pincus, M. R.;
Sardana, M.; Henderson, C. J.; Wolf, C. R., et al EMBO J. 1999, 18, 1321.
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Compound 9r: 2-[2,3-dichloro-4-(2-methylene-1-oxo-butyl)
phenoxymethyl]-4-(4-trifluoromethylphenyl)thiazole, white pow-
der, yield 58.5%, mp 88–90 °C. 1H NMR (DMSO-d6) d: 8.01 (d,
J = 7.80 Hz, 2H), 7.69 (d, J = 8.40 Hz, 2H), 7.67 (s, 1H), 7.17 (d,
J = 9.00 Hz, 1H), 7.04 (d, J = 8.40 Hz, 1H), 5.95 (s, 1H) 5.60 (s, 1H),
5.54 (s, 2H), 2.47 (q, J = 7.20 Hz, 2H), 1.15 (t, J = 7.20 Hz, 3H). IR
(KBr, cmÀ1):
C@O: 1660.78;
m@CH: 3115.37;
mCH: 2971.43, 2933.25, 2876.80;
m
m
C@C: 1616.31, 1584.58, 1512.46, 1469.03; dCH
:
1328.46, 1300.83;
m
C–O: 1267.77;
c
@CH: 1069.99, 1047.60, 855.22,
801.43, 766.11. HRMS (ESI) m/z for C22H17Cl2F3NO2S [M+H]+:
13. Zhao, G.; Wang, X. Curr. Med. Chem. 2006, 13, 1461.
14. Awasthi, S.; Srivastava, S. K.; Ahmad, F.; Ahmad, H.; Ansari, G. A. Biochim.
Biophys. Acta. 1993, 1164, 173.
calculated 486.0304 found 486.0301.
15. Yang, X.; Liu, G.; Li, H.; Zhang, Y.; Song, D.; Li, C.; Wang, R.; Liu, B.; Liang, W.,
et al J. Med. Chem. 2010, 53, 1015.
3.8. GSTpi activity inhibition assay
16. Muller, J.; Sidler, D.; Nachbur, U.; Wastling, J.; Brunner, T.; Hemphill, A. Int. J.
Cancer 2008, 123, 1797.
17. Zhao, G.; Yu, T.; Wang, R.; Wang, X.; Jing, Y. Bioorg. Med. Chem. 2005, 13, 4056.
18. Karegoudar, P.; Karthikeyan, M. S.; Prasad, D. J.; Mahalinga, M.; Holla, B. S.;
Kumari, N. S. Eur. J. Med. Chem. 2008, 43, 261.
HL-60 cells were cultured in RPMI-1640 medium supplemented
with 100 U/mL penicillin, 100
lg/mL streptomycin, 1 mmol/L
L
-glutamine, and 10% heat-inactivated fetal bovine serum in a
humidified atmosphere of 95% air and 5% CO2 at 37 °C. Cell lysates
were prepared as we reported before and the GSTpi activity was
19. Zhao, G.; Liu, C.; Wang, R.; Song, D.; Wang, X.; Lou, H.; Jing, Y. Bioorg. Med.
Chem. 2007, 15, 2701.