Synthesis and evaluation of substituted 4-aryloxy- and 4-arylsulfanyl- phenyl-2-aminothiazoles as inhibitors of human breast cancer cell proliferation

Article abstract of DOI:10.1016/j.bmc.2003.12.003

Several substituted 4-aryloxy- and 4-arylsulfanyl-phenyl-2-aminothiazoles were synthesized and evaluated for cytotoxic activity against estrogen-positive, estrogen-negative, and adriamycin-resistant human breast cancer cell lines. 4-[4′-(3,4-Dichlorophenoxy)-phenyl]-thiazol-2-yl ammonium iodide demonstrated potent activity against both estrogen-positive and negative breast cancer cell lines with low micromolar (μM) GI₅₀ values. In addition, we have identified several 2-aminothiazoles that demonstrated selective potency for the adriamycin-resistant and estrogen-negative breast cancer cell lines. The results suggest that these 2-aminothiazoles represent lead compounds for evaluation in animal models of breast cancer.

Full text of DOI:10.1016/j.bmc.2003.12.003

Bioorganic & Medicinal Chemistry 12 (2004) 1029–1036
Synthesis and evaluation of substituted 4-aryloxy- and
4-arylsulfanyl-phenyl-2-aminothiazoles as inhibitors of
human breast cancer cell proliferation
Michael J. Gorczynski,a Rachel M. Leal,b Susan L. Mooberry,b John H. Bushwellera,c
and Milton L. Browna,*
aDepartment of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
bDepartment of Physiology and Medicine, Southwest Foundation of Biomedical Research, San Antonio, TX 78245, USA
cDepartment of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22906, USA
Received 22 August 2003; revised 25 November 2003; accepted 10 December 2003
Abstract—Several substituted 4-aryloxy- and 4-arylsulfanyl-phenyl-2-aminothiazoles were synthesized and evaluated for cytotoxic
activity against estrogen-positive, estrogen-negative, and adriamycin-resistant human breast cancer cell lines. 4-[40-(3,4-Dichloro-
phenoxy)-phenyl]-thiazol-2-yl ammonium iodide demonstrated potent activity against both estrogen-positive and negative breast
cancer cell lines with low micromolar (mM) GI50 values. In addition, we have identified several 2-aminothiazoles that demonstrated
selective potency for the adriamycin-resistant and estrogen-negative breast cancer cell lines. The results suggest that these 2-ami-
nothiazoles represent lead compounds for evaluation in animal models of breast cancer.
# 2003 Elsevier Ltd. All rights reserved.
1. Introduction
radiation or a simple mastectomy are possible treatment
options for patients with DCIS. There is a 20–30% risk
of developing invasive breast cancer for women with
LCIS and as a result, it is managed with careful bilateral
breast observation. Invasive cancers are treated surgically
by either a modified radical mastectomy with axillary
lymph node dissection or a lumpectomy with axillary
lymph node dissection followed by local radiation.
Surgical treatment options are standard treatment
therapies for DCIS and invasive cancers followed by
post-surgical (adjuvant) treatment. These adjuvant
therapies have improved survival rates of women with
these types of breast cancer. In addition to surgical
options, adjuvant drug therapy can decrease the risk of
systemic recurrence by approximately one third.
Breast cancer is the most common cancer and second
most frequent cause of cancer death among women. The
National Cancer Institute (NCI) estimates 211,000 new
breast cancer cases and 40,000 deaths for 2003.1 There
are two types of breast cancer: in situ and invasive. In
situ breast cancer is divided into two subtypes: ductal
cystic (DCIS) and lobular cystic (LCIS). Infiltrating
ductal carcinoma is the most common type of invasive
breast cancer accounting for approximately 70% of all
breast cancer diagnoses. Another type of invasive breast
cancer is infiltrating lobular carcinoma. This form
accounts for 5–10% of invasive breast cancers. In addition,
there are a few less common histologic subtypes of
invasive cancer including medullary, mucinous, and
tubular.
Adjuvant treatments include cytotoxic chemotherapy
(i.e., paclitaxel, doxorubicin), hormonal therapy (i.e.,
tamoxifen), or a combination of the two. These treatments
are not without severe side effects. Paclitaxel inhibits
microtubule disassembly and is active against a wide
range of human tumors.2 The major side effects of
paclitaxel are neutropenia, neurotoxicity, and cardio-
toxicity.2 Doxorubicin is one of the most active
cytotoxic agents against breast cancer,3 but side effects,4
such as cardiotoxicity and myelosuppression, have
Current treatment for breast cancer depends on the
patient’s type of breast cancer. Local incision plus
Keywords: 2-Aminothiazoles; Diaryl ethers; Breast cancer; Substituent
effects.
* Corresponding author. Tel.:+1-434-982-3091; fax:+1-434-924-0798;
e-mail: mlb2v@virginia.edu
0968-0896/$ - see front matter # 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2003.12.003

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M. J. Gorczynski et al. / Bioorg. Med. Chem. 12 (2004) 1029–1036
hindered this drug’s use in adjuvant therapy. Tamoxifen
is the only drug approved by the United States Food
and Drug Administration for breast cancer risk reduc-
tion in estrogen-sensitive breast cancer.5 Women
receiving tamoxifen may experience more frequent hot
flashes, develop cataracts, and have an increased risk for
venous thromboembolic events and strokes.5 Tamoxifen
use is also associated with increased endometrial cancer
risk in postmenopausal women with a uterus.5 A s a
result of the side effects caused by the current adjuvant
treatments, there is a need for safer, more potent breast
cancer agents.
synthesis of a number of 4-aryloxy- and 4-arylsulfanyl-
phenyl-2-aminothiazoles (Fig. 2) and the evaluation of
these compounds for efficacy against a panel of human
breast cancer cell lines that represent a clinical spectrum
of estrogen-positive, estrogen-negative, and adriamycin-
resistant breast cancer.
2. Results and discussion
Ageneral synthesis of the substituted 4-aryloxy- and 4-
arylsulfanyl-phenyl-2-aminothiazole salts is shown in
Scheme 1. Condensation of the appropriately sub-
stituted phenols with 40-fluoroacetophenone afforded
the corresponding 4-aryloxyacetophenones in 40–93%
yield.12 This condensation reaction also proceeded
smoothly with various substituted benzenethiols forming
the 4-arylsulfanylacetophenones in 38–87% yield.
Treatment of the acetophenones with thiourea and
iodine successfully generated the 2-aminothiazole salts
(Table 1) in 40–98% yield.13
2-Aminothiazoles represent a fairly new class of breast
cancer drugs with only a few examples in the literature
(Fig. 1). Currently, a number of aminothiazolecarboni-
triles6 and thiazolylaminopyridines7,8 are being investi-
gated for their use as tyrosine kinase inhibitors.
Aminothiazole inhibitors of cyclin-dependent kinase 2
have been shown to have significant antitumor activity
in breast cancer models.9 Thiophene-2-carboxamidines
containing 2-aminothiazoles have been evaluated as
serine protease urokinase inhibitors.10 In addition to 2-
aminothiazoles, there are also few examples in the
breast cancer literature of compounds containing diaryl
ethers. Anumber of diaryl ether compounds have been
evaluated as anti-cancer agents,11 but to the best of our
knowledge, there are no anti-cancer reports of diaryl
ethers with a 2-aminothiazole moiety. We report the
Upon completion of the synthesis, the thiazole com-
pounds 17–24 and 27–30 were submitted to the NCI’s
antitumor screen14,15 and the results against human
breast cancer cell lines are shown in Table 2 as GI50
values. Although not effective against other types of
cancer, compound 17 showed selectivity for T-47D
breast cancer cells (Fig. 3) with a GI50 of 0.917 mM.
Compounds 20 and 28 showed selectivity for the adria-
mycin-resistant cell line with GI50 values of 1.29 and
3.37 mM, respectively. Adriamycin-resistant selectivity is
clinically important because patients develop cancer
that is resistant to treatment.
Table 1. Thiazoles
Compd
X
R1
R2
R3
% Yield
Figure 1. Several examples of current 2-aminothiazoles being investi-
gated for breast cancer activity.
17
18
19
20
21
22
23
24
25
26
27
28
29
30
O
O
O
O
O
O
O
O
O
S
H
H
Cl
H
H
H
H
H
H
H
H
H
H
H
H
Cl
H
Cl
H
H
H
H
CO2Et
H
Cl
H
H
Cl
OMe
Me
Ph
OPh
H
H
Cl
Cl
OMe
Me
71
65
40
75
87
65
70
86
64
98
98
48
91
54
S
S
S
S
H
Cl
H
Figure 2. General structure of 4-aryloxy- and 4-arylsulfanyl-phenyl-2-
aminothiazole salts.
H
Scheme 1. Synthesis of acetophenones and thiazoles. Reagents and conditions: (a) phenol or thiol, K2CO3, DMAC, reflux, 8–10 h, 38–93%;
(b) thiourea, I2, EtOH, 100 ꢀC, 3 h, 40–98%.

M. J. Gorczynski et al. / Bioorg. Med. Chem. 12 (2004) 1029–1036
Table 2. Human breast cancer cytotoxicity data
1031
Compd
% Inhibition of
GI50 (mM)
MCF7 at 100 mM
MCF7
NCI/ADR-RES
MDA-MB-231/ATCC
HS 578T
MDA-MB-435
BT-549
T-47D
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
81
85
100
87
47
24
98
53
81
84
79
89
54
11
96
ND
>100
14.6
27.4
3.02
ND
17.2
14.3
35.1
ND
ND
21.6
5.68
ND
25.9
ND
>100
13.2
25.8
1.29
ND
18.2
17.4
35.9
ND
ND
17.5
3.37
ND
64.6
ND
>100
4.8
ND
>100
19.7
ND
2
ND
22.7
18.8
27.8
ND
ND
18.8
ND
ND
59.6
ND
>100
2.1
ND
>100
14.3
12.8
1.91
ND
ND
10.4
16.1
ND
ND
15.3
5.95
ND
25.7
ND
0.917
14
16.4
20.9
ND
0.54
3.91
4.9
ND
ND
24.4
2.79
ND
68
10.5
2.29
ND
14.1
12.6
12.6
ND
ND
12.4
3.73
ND
>100
14.8
0.759
ND
11.8
18.6
22.7
ND
ND
1.49
1.11
ND
1.4
Figure 3. GI50 comparison for compound 17 for all NCI cell lines. L=Leukemia; NSCLC=Non-small cell lung cancer; C=Colon; CNS=Central
nervous system; M=Melanoma; O=Ovarian; R=Renal; P=Prostate; B=Breast.
Interestingly, when the GI50 values of compounds 17
(X=O) and 27 (X=S) are compared, there appears to
be a relationship between heteroatom substitution and
selectivity for the estrogen-positive or estrogen-negative
cell lines. The GI50 of 17 exceeded 100 mM in all cell
lines except for the estrogen-positive cell line T-47D in
which the GI50 was 0.917 mM, while the GI50 of 27 was
24.4 mM for the T-47D cell line. Compound 27 showed
greater selectivity for the estrogen-negative cell line
MDA-MB-435 with a GI50 of 1.49 mM when compared
with greater than 100 mM for 17. The aforementioned
selectivity was also seen for 22 and 30 for the same cell
lines. These results strongly suggest that estrogen-positive
selectivity appears to be achieved using an oxygen linkage
whereas compounds with a sulfur linkage are significantly
more active against estrogen-negative breast cancer cell
types. Thiazole 20 exhibited low micromolar cytotoxicity
in all breast cancer cell lines except T-47D and was
the only compound to show significant cytotoxicity in
the estrogen-negative HS-578T cell line with a GI50 of 2
mM. Low micromolar cytotoxicity was also observed for
28 which was active in all cell lines except HS 578T with
GI50 values in the 1–5 mM range. Compounds 20 and 28
have similar 3,4-dichloro substitutions on their outer
phenyl ring and differ only in the heteroatom that links
the two rings. Thiazoles 22–24 demonstrated selectivity

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M. J. Gorczynski et al. / Bioorg. Med. Chem. 12 (2004) 1029–1036
for the estrogen-positive cell line T-47D with GI50
values of 0.54 mM, 3.91 mM, and 4.90 mM, respectively.
Compound 30 was selective against the MDA-MB-435
cell line with a GI50 of 1.4 mM. In addition to the selec-
tivity attained with different linkages between the two
phenyl rings, these thiazoles also exhibit several distinct
structure–activity relationships for substitution on the
outer phenyl ring.
Thiazoles 20 and 28, both with 3,4-dichloro substitu-
tions, exhibited selectivity for the adriamycin-resistant
cell line. These thiazoles represent promising lead com-
pounds for the development of selective thiazole-con-
taining breast cancer agents and are candidates for
further mechanistic studies.
4. Experimental
For the oxygen linker series, thiazole 22 with an electron-
donating para-methyl substituent shows increased efficacy
over the electron-withdrawing para-chloro thiazole 17 in
all cell lines. An increase in bulk at the para position
from methyl to phenyl does not significantly alter activity.
Chlorine substitution at the ortho, meta, and para posi-
tions was also investigated with compounds 17–19. In
most of the cell lines, the best activity was achieved by
chloro substitution at the meta position. Substitution at
the ortho position showed a slight decrease in activity
whereas the para-chloro thiazole had GI50 values
greater than 100 mM in all cell lines except T-47D.
Although the meta- and para- chloro thiazoles were less
active than the ortho-chloro compound, chlorine sub-
stitution at both the meta and para positions provided
the most active compound out of this series.
All starting materials were purchased from Aldrich and
were used as received. Melting points were measured on
an Electrothermal Mel-Temp and are uncorrected. Carbon
and proton NMR spectra were recorded on a General
Electric 300 MHz spectrometer. Mass spectra were
obtained on a Finnagan LcQ Classic spectrometer.
High resolution (EI) mass spectra were obtained from
the University of Illinois, Urbana-Champaign. Combus-
tion analyses were performed by Atlantic Microlabs Inc.
4.1. General procedure for synthesis of 4-aryloxy and
4-arylsulfanyl substituted acetophenones12 (2–15)
Anhydrous K2CO3 (12 mmol) was added to a solution
of 40-fluoroacetophenone (10 mmol) and the corres-
ponding phenol or thiol (10 mmol) in N,N-dimethyl-
acetamide (DMAC, 10 mL). The suspension was
refluxed for 8–10 h, cooled to room temperature, and
diluted with H2O (10 mL). In some instances (8 and 9),
the addition of H2O resulted in the deposition of the
product as a solid which was collected by filtration. In
those instances where the product was not a solid, the
resulting solution was extracted with CHCl3 (3ꢁ15 mL),
dried over MgSO4, and concentrated in vacuo to yield a
brown oil. The remaining DMAC was removed by
Kugelrohr distillation. The viscous oil was allowed to
cool and solidify. The crude solid was recrystallized
from EtOH.
While a para electron-donating group was more active
(compared GI50 of 22 to that of 17) than a para electron-
withdrawing group for the oxygen linker series, the
opposite relationship was observed for compounds
with the thioether linkage. Generally, for this series of
compounds, the para chloro thiazole was more active
(compared GI50 of 27 to that of 30) than the para-
methyl thiazole.
Thiazoles 17 and 22–24 were selective for the estrogen-
positive cell line T-47D. Although these thiazoles may
work through a tamoxifen-like mechanism, further
studies are in progress for these compounds. However,
thiazoles 18, 27, and 30 appear to be active only against
estrogen-negative breast cancer thereby ruling out a
tamoxifen-like mechanism of action for these structural
analogues.
4.2. 4-(40-Chlorophenoxy)-acetophenone (2)
Isolated as a light brown solid (1.81 g, 73%); mp 65–
66 ꢀC (lit.12 66–68 ꢀC); 1H NMR (CDCl3) d 2.57 (s, 3H),
6.99 (d, J=6.4 Hz, 4H), 7.35 (d, J=8.3 Hz, 2H), 7.94
(d, J=8.2 Hz, 2H); 13C NMR d 27.0, 117.8, 121.7,
130.2, 130.6, 131.2, 132.8, 154.7, 162.0, 197.1; MS APCI
m/z 247 (M)+.
In addition, the thiazoles were evaluated for their ability
to disrupt cellular microtubules and for changes in cell
cycle distribution as previously described.16 The results
indicate that these compounds are not microtubule or
microfilament inhibitors and they do not alter cell cycle
distribution.
4.3. 4-(30-Chlorophenoxy)-acetophenone (3)
Isolated as an orange oil (2.03 g, 82%); 1H NMR
(CDCl3) d 2.49 (s, 3H), 6.82–7.13 (m, 5H), 7.22 (t,
J=7.9 Hz, 1H), 7.88 (d, J=7.7 Hz, 2H); 13C NMR d
26.9, 109.9, 118.3, 118.5, 120.6, 125.0, 131.1, 133.0,
135.7, 157.0, 161.4, 196.9; MS APCI m/z 247 (M)+.
3. Conclusion
In conclusion, we have synthesized a series of 4-aryloxy-
and 4-arylsulfanyl-phenyl-2-aminothiazoles. Compounds
17, 18, 22, 24, 27, and 30 demonstrated selective cyto-
toxicity of either estrogen-positive or negative breast
cancer cells while compounds 20 and 28 showed low
micromolar growth inhibition of most human breast
tumor cells. In general, thiazoles with an oxygen linkage
showed estrogen-positive selectivity whereas estrogen-
negative selectivity was achieved by thioether linkages.
4.4. 4-(20-Chlorophenoxy)-acetophenone (4)
Isolated as a yellow solid (1.64 g, 67%); mp 41–43 ꢀC
(lit.17 49–50 ꢀC); H NMR (CDCl3) d 2.47 (s, 3H), 6.85
1
(d, J=8.3 Hz, 2H), 6.99–7.16 (m, 2H), 7.21 (d, J=7.5
Hz, 1H), 7.39 (d, J=7.5 Hz, 1H), 7.86 (d, J=8.3 Hz,
2H); 13C NMR d 26.9, 109.9, 116.8, 123.0, 126.7, 127.2,

M. J. Gorczynski et al. / Bioorg. Med. Chem. 12 (2004) 1029–1036
1033
128.9, 131.1, 131.5, 132.5, 151.2, 161.7, 196.9; MS APCI
m/z 247 (M)+.
(d, J=8.1 Hz, 2H), 7.40–7.47 (m, 5H), 7.82 (d, J=8.1
Hz, 2H); 13C NMR d 13.7, 128.0, 129.3, 129.4, 130.2,
132.6, 134.4, 135.0, 145.4, 192.9; MS APCI m/z 229
(M)+.
4.5. 4-(30,40-Dichlorophenoxy)-acetophenone (5)
Recrystallized from hexanes to afford a brown solid
(2.61, 93%); mp 47–49 ꢀC (lit.18 50–52 ꢀC); H NMR
4.12. 4-(40-Chloro-phenylsulfanyl)-acetophenone (12)
1
(CDCl3) d 2.57 (s, 3H), 6.90 (d, J=8.4 Hz, 1H), 7.01 (d,
J=8.5 Hz, 2H), 7.14 (s, 1H), 7.42 (d, J=8.6 Hz, 1H),
7.95 (d, J=8.3 Hz, 2H); 13C NMR d 27.0, 118.4, 119.7,
122.2, 128.5, 131.2, 131.8, 133.3, 134.0, 155.3, 161.2,
197.1; MS APCI m/z 281 (M)+.
Isolated as an orange solid (1.68 g, 64%); mp 40–42 ꢀC;
1H NMR (CDCl3) d 2.56 (s, 3H), 7.22 (d, J=8.1 Hz,
2H), 7.38 (d, J=6.5 Hz, 4H), 7.83 (d, J=7.9 Hz, 2H);
13C NMR d 27.0, 128.3, 129.5, 130.4, 131.4, 135.4,
143.7, 144.5, 147.8, 197.5; MS APCI m/z 263 (M)+.
4.6. 4-(40-Methoxyphenoxy)-acetophenone (6)
4.13. 4-(30,40-Dichloro-phenylsulfanyl)-acetophenone (13)
1
Isolated as a light brown solid (2.02 g, 84%); mp 56–
Isolated as a red oil (1.44 g, 87%); H NMR (CDCl3) d
58 ꢀC (lit.19 61 ꢀC); H NMR (CDCl3) d 2.55 (s, 3H),
2.56 (s, 3H), 7.23–7.33 (m, 2H), 7.39–7.53 (m, 1H), 7.85
(d, J=8.1 Hz, 4H); 13C NMR d 27.0, 129.4, 129.7,
131.6, 131.8, 132.3, 133.6, 133.9, 134.0, 134.5, 136.0,
197.5; MS APCI m/z 297 (M)+.
1
3.81 (s, 3H), 6.90–7.00 (m, 6H), 7.90 (d, J=7.9 Hz, 2H);
13C NMR d 26.9, 56.1, 115.6, 116.9, 122.2, 131.1, 131.9,
149.0, 157.2, 163.4, 197.2; MS APCI m/z 243 (M)+.
4.7. 4-(p-Toluoxy)-acetophenone (7)
4.14. 4-(40-Methoxy-phenylsulfanyl)-acetophenone (14)
Isolated as a red solid (1.49 g, 58%); mp 25–27 ꢀC; H
1
Isolated as a light brown solid (0.91 g, 40%); mp 44–
46 ꢀC; H NMR (CDCl3) d 2.37 (s, 3H), 2.57 (s, 3H),
NMR (CDCl3) d 2.51 (s, 3H), 3.83 (s, 3H), 6.94 (d,
J=8.1 Hz, 2H), 7.07 (d, J=8.1 Hz, 2H), 7.45 (d, J=8.1
Hz, 2H), 7.76 (d, J=8.1 Hz, 2H); 13C NMR d 26.9,
55.9, 115.9, 121.8, 126.3, 129.3, 134.4, 137.3, 147.4,
161.2, 197.6; MS APCI m/z 259 (M)+.
1
6.97 (d, J=7.5 Hz, 4H), 7.19 (d, J=7.7 Hz, 2H), 7.92
(d, J=8.5 Hz, 2H); 13C NMR d 21.3, 26.9, 117.4, 120.5,
120.7, 131.1, 132.1, 134.9, 153.5, 163.0, 197.2; MS APCI
m/z 227 (M)+.
4.8. 4-(Biphenyl-40-yloxy)-acetophenone (8)
4.15. 4-(40-Tolylsulfanyl)-acetophenone (15)
Isolated as a red solid (1.64 g, 68%); mp 90–92 ꢀC; H
1
Isolated as a pale yellow solid (2.61 g, 90%); mp 114–
117 ꢀC; 1H NMR (CDCl3) d 2.59 (s, 3H), 7.06 (d, J=8.3
Hz, 2H), 7.14 (d, J=8.1 Hz, 2H), 7.36 (d, J=8.0 Hz,
1H), 7.44 (t, J=7.4 Hz, 2H), 7.60 (t, J=7.1 Hz, 4H),
7.96 (d, J=8.0 Hz, 2H); 13C NMR d 27.0, 117.9, 120.9,
127.5, 127.8, 129.2, 129.4, 131.1, 132.5, 138.2, 140.8,
155.5, 162.4, 197.2; MS APCI m/z 289 (M)+.
NMR (CDCl3) d 2.40 (s, 3H), 2.54 (s, 3H), 7.15 (d,
J=8.1 Hz, 2H), 7.22 (d, J=7.7 Hz, 2H), 7.41 (d, J=7.5
Hz, 2H), 7.79 (d, J=8.0 Hz, 2H); 13C NMR d 21.8,
27.0, 127.2, 128.4, 129.3, 131.0, 134.6, 135.0, 140.0,
146.4, 197.6; MS APCI m/z 243 (M)+.
4.16. General procedure for synthesis of substituted 4-ar-
yloxy and 4-arylsulfanyl-phenyl-2-aminothiazole salts13
(16–30)
4.9. 4-(40-Phenoxy-phenoxy)-acetophenone (9)
Isolated as a white solid (2.47 g, 81%); mp 75–77 ꢀC; 1H
NMR (CDCl3) d 2.57 (s, 3H), 6.80–7.40 (m, 11H), 7.94
(d, J=8.1 Hz, 2H); 13C NMR d 26.9, 117.3, 119.2,
120.9, 122.1, 123.9, 130.3, 131.1, 132.3, 151.3, 154.5,
157.8, 162.9, 197.2; MS APCI m/z 305 (M)+.
Thiourea (40 mmol) and iodine (11 mmol) were added
to a stirring solution of the appropriate acetophenone
(10 mmol) in absolute ethanol (20 mL). The mixture
was heated at 100 ꢀC for 2–3 h in an open vessel. The
crude residue was washed with ether (3ꢁ50 mL) and
was recrystallized from hot water. Afew of these com-
pounds (16,21 17,22 and 2621) in free amine or HCl salt
form are reported in the literature.
4.10. Ethyl 3-(40-acetyl-phenoxy)-benzoate (10)
Isolated as a yellow oil (1.92 g, 68%); 1H NMR
(CDCl3) d 1.37 (t, J=6.7 Hz, 3H), 2.56 (s, 3H), 4.35 (q,
J=7.1 Hz, 3H), 6.98 (d, J=8.1 Hz, 2H), 7.24 (d, J=7.9
Hz, 1H), 7.44 (t, J=7.5 Hz, 1H), 7.71 (s, 1H), 7.86 (d,
J=7.5 Hz, 1H), 7.93 (d, J=8.1 Hz, 3H); 13C NMR d
14.8, 26.9, 61.8, 118.0, 121.5, 125.0, 126.1, 130.5, 131.2,
132.8, 133.2, 156.1, 161.9, 166.2, 197.1; MS APCI m/z
285 (M)+.
4.17.
iodide (16)
4-(40-Phenoxyphenyl)-thiazol-2-yl
ammonium
Isolated as a yellow solid (1.82 g, 46%); mp 193–195 ꢀC;
1H NMR (DMSO-d6) d 7.02 (t, J=8 Hz, 4H), 7.08 (s,
1H), 7.13 (t, J=6.2 Hz, 1H), 7.37 (t, J=7.7 Hz, 2H),
7.65 (d, J=8.1 Hz, 2H); 13C NMR d 103.0, 119.5, 120.1,
125.1, 128.8, 131.2, 140.1, 145.7, 156.4, 158.6, 171.1; MS
APCI m/z 269 (M-HI)+. Anal. calcd for C15H13IN2OS:
C, 45.47; H, 3.31; N, 7.07. Found: C, 45.25; H, 3.26; N,
7.08.
4.11. (40-Phenylsulfanyl)-acetophenone (11)
Isolated as an orange solid (0.87 g, 38%); mp 59–61 ꢀC
(lit.20 67–68 ꢀC); H NMR (CDCl3) d 2.55 (s, 3H), 7.21
1

1034
M. J. Gorczynski et al. / Bioorg. Med. Chem. 12 (2004) 1029–1036
4.18. 4-[40-(4-Chlorophenoxy)-phenyl]-thiazol-2-yl ammo-
nium iodide (17)
4.23. 4-[40-(p-Toluoxy)phenyl]-thiazol-2-yl ammonium
iodide (22)
Isolated as a light orange solid (0.31 g, 71%); mp 152–
Isolated as a light brown solid (0.27 g, 65%); mp 118–
154 ꢀC; H NMR (DMSO-d6) d 6.95–7.10 (m, 5H), 7.41
120 ꢀC; H NMR (DMSO-d6) d 2.26 (s, 3H), 6.90–7.03
1
1
(t, J=6.6 Hz, 2H), 7.67 (d, J=8.7 Hz, 1H), 7.92 (d,
J=8.7 Hz, 1H), 8.94 (br s); 13C NMR d 109.8, 118.6,
118.8, 121.9, 123.1, 128.9, 131.0, 131.2, 131.7, 155.6,
170.0; HRMS calcd for C15H12ClIN2OS (M-HI)+ m/z
303.036100, found m/z 303.035888.
(m, 5H), 7.19 (t, J=7.9 Hz, 2H), 7.65 (d, J=8.6 Hz,
1H), 7.90 (d, J=6.7 Hz, 1H); 13C NMR d 27.5, 117.6,
118.9, 120.3, 121.0, 128.6, 131.5, 131.6, 134.2, 134.9,
161.2, 162.6; MS APCI m/z 283 (M-HI)+. Anal. calcd
for C16H15IN2OS: C, 46.84; H, 3.69, N, 6.83. Found: C,
46.65; H, 3.86; N, 6.61.
4.19. 4-[4-(30-Chlorophenoxy)-phenyl]-thiazol-2-yl ammo-
nium iodide (18)
4.24. 4-[40-(Biphenyl-4-yloxy)-phenyl]-thiazol-2-yl ammo-
nium iodide (23)
Isolated as a yellow solid (0.57 g, 65%); mp 107–110 ꢀC;
1H NMR (DMSO-d6) d 6.96 (d, J=7.9 Hz, 1H), 7.11 (s,
1H), 7.18 (d, J=8.1 Hz, 1H), 7.39 (t, J=7.5 Hz, 1H),
7.70 (d, J=8.2 Hz, 4H), 7.93 (d, J=7.8 Hz, 1H), 8.96
(br s); 13C NMR d 103.2, 113.9, 118.4, 119.7, 120.2,
124.8, 128.9, 132.6, 135.0, 144.1, 157.6, 160.6, 171.0;
HRMS calcd for C15H12ClIN2OS (M-HI)+ m/z
303.036700, found m/z 303.035888. Anal. calcd for
Isolated as a yellow solid (0.33 g, 70%); mp 253–254 ꢀC;
1H NMR (DMSO-d6) d 7.00–7.20 (m, 4H), 7.30 (d,
J=6.5 Hz, 1H), 7.40 (t, J=7.3 Hz, 2H), 7.66 (m,
6H), 7.93 (d, J=8.0 Hz, 1H); 13C NMR d 102.8,
119.8, 120.4, 127.4, 128.2, 128.8, 129.4, 129.5, 129.9,
136.7, 137.3, 156.4, 158.2, 159.4, 177.5; HRMS calcd
for C21H17IN2OS (M-HI)+ m/z 345.106200, found
m/z 345.106160. Anal. calcd for C21H17IN2OS: C,
53.40; H, 3.63; N, 5.93. Found. C, 53.65; H, 3.65; N,
5.80.
.
C15H12ClIN2OS 0.6H2O: C, 40.81; H, 2.72; N, 6.34.
Found: C, 40.53; H, 2.60; N, 6.10.
4.20. 4-[4-(20-Chlorophenoxy)-phenyl]-thiazol-2-yl ammo-
nium iodide (19)
4.25.
ammonium iodide (24)
4-[40-(4-Phenoxy-phenoxy)-phenyl]-thiazol-2-yl
Isolated as a yellow solid (0.35 g, 40%); mp 160–163 ꢀC;
1H NMR (DMSO-d6) d 6.98 (d, J=8.3 Hz, 2H), 7.08 (s,
1H), 7.17 (d, J=8.1 Hz, 1H), 7.23 (t, J=6.6 Hz, 1H),
7.37 (t, J=7.7 Hz, 1H), 7.58 (d, J=7.6 Hz, 1H), 7.68 (d,
J=8.3 Hz, 2H), 8.99 (br s); 13C NMR d 103.0, 118.2,
123.0, 126.9, 127.2, 128.9, 130.0, 131.7, 131.8, 133.4,
147.5, 158.3, 171.0; MS APCI m/z 303 (M-HI)+. Anal.
calcd for C15H12ClIN2OS: C, 41.83; H, 2.81; N, 6.50.
Found: C, 41.65; H, 2.71; N, 6.48.
Isolated as a pale yellow solid (0.42 g, 86%); mp 137–
140 ꢀC; 1H NMR (DMSO-d6) d 6.95–7.12 (m, 10H),
7.34 (t, J=7.4 Hz, 2H), 7.67 (d, J=8.1 Hz, 1H), 7.92
(d, J=8.3 Hz, 1H); 13C NMR d 102.8, 117.7, 119.2,
119.3, 121.4, 122.0, 122.7, 124.3, 128.8, 131.0, 131.7,
143.9, 152.3, 153.3, 161.1; HRMS calcd for
C21H17IN2O2S (M-HI)+ m/z 361.101000, found m/z
361.101075.
4.21.
ammonium iodide (20)
4-[40-(3,4-Dichlorophenoxy)-phenyl]-thiazol-2-yl
4.26. 4-[4-(30-Ethoxycarbonyl-phenoxy)-phenyl]-thiazol-
2-yl ammonium iodide (25)
Isolated as a brown solid (0.35 g, 75%); mp 202–205 ꢀC;
1H NMR (DMSO-d6) d 7.07 (d, J=7.5 Hz, 3H), 7.14 (s,
1H), 7.37 (s, 1H), 7.62 (d, J=8.2 Hz, 1H), 7.70 (d,
J=8.1 Hz, 1H), 7.93 (d, J=8.1 Hz, 1H), 9.02 (br s); 13C
NMR d 103.4, 118.9, 120.2, 120.9, 121.7, 122.6, 129.0,
131.7, 132.7, 133.2, 133.5, 161.0, 171.1; HRMS calcd for
C15H11Cl2IN2OS (M-HI)+ m/z 336.997000, found m/z
336.996915. Anal. calcd for C15H11Cl2IN2OS 0.9H2O:
C, 37.43; H, 2.28; N, 5.82. Found: C, 37.19; H, 2.25; N,
5.66.
Isolated as a yellow solid (1.01 g, 64%); mp 158–160 ꢀC;
1H NMR (DMSO-d6) d 1.24 (t, J=6.3 Hz, 3H), 4.24 (q,
J=7.0 Hz, 2H), 7.10 (s, 3H), 7.34 (d, J=7.9 Hz, 1H),
7.45 (s, 1H), 7.51 (t, J=7.7 Hz, 1H), 7.71 (d, J=7.2 Hz,
2H), 7.94 (d, J=7.9 Hz, 1H), 8.83 (br s); 13C NMR d
15.0, 62.0, 103.2, 109.8, 118.7, 119.6, 120.1, 124.8, 125.5,
129.0, 131.8, 132.8, 157.3, 157.9, 165.9, 171.0; HRMS
calcd for C18H17IN2O3S (M-HI)+ m/z 341.095700,
found m/z 341.095989. Anal. calcd for C18H17-
.
.
IN2O3S 2H2O: C, 42.87; H, 3.37; N, 5.55. Found: C,
42.58; H, 3.26; N, 5.51.
4.22.
ammonium iodide (21)
4-[40-(4-Methoxyphenoxy)-phenyl]-thiazol-2-yl
4.27. 4-(40-Phenylsulfanyl-phenyl)-thiazol-2-yl ammo-
nium iodide (26)
Isolated as a yellow solid (0.37 g, 87%); mp 204–207 ꢀC;
1H NMR (DMSO-d6) d 3.71 (s, 3H), 6.95–7.03 (m, 5H),
7.05 (s, 1H), 7.62 (d, J=8.2 Hz, 2H), 7.98 (d, J=7.9 Hz,
1H), 8.93 (br s); 13C NMR d 56.4, 102.6, 116.2, 117.1,
118.2, 122.1, 122.6, 124.5, 128.7, 131.6, 150.0, 171.1; MS
APCI m/z 299 (M-HI)+. Anal. calcd for C16H15IN2O2S:
C, 45.08; H, 3.55; N, 6.57. Found: C, 44.97; H, 3.65; N,
6.67.
Isolated as an orange solid (0.40 g, 98%); mp 129–
132 ꢀC; H NMR (DMSO-d6) d 7.15 (s, 1H), 7.26–7.47
1
(m, 6H), 7.65 (d, J=7.5 Hz, 2H), 7.81 (d, J=7.5 Hz,
1H); 13C NMR d 104.0, 127.7, 128.4, 129.0, 130.0,
130.7, 131.1, 132.5, 164.0, 170.8, 177.5; HRMS calcd for
C15H13IN2S2 (M-HI)+ m/z 285.052200, found m/z
285.052017.

M. J. Gorczynski et al. / Bioorg. Med. Chem. 12 (2004) 1029–1036
1035
4.28. 4-[4-(40-Chloro-phenylsulfanyl)-phenyl]-thiazol-2-yl
ammonium iodide (27)
10-fold dilutions. A48 h continuous drug exposure
protocol was used, and a sulforhodamine B (SRB) protein
assay was used to estimate cell viability or growth.
Isolated as an orange solid (0.44 g, 98%); mp 158–
160 ꢀC; H NMR (DMSO-d6) d 7.14 (s, 1H), 7.24–7.47
1
4.34. Inhibition of breast cell proliferation
(m, 6H), 7.68 (d, J=7.9 Hz, 2H); 13C NMR d 101.3,
110.1, 127.6, 127.9, 130.6, 132.0, 133.5, 143.6, 154.7,
167.8, 169.8; HRMS calcd for C15H12ClIN2S2 (M-HI)+
m/z 319.012900, found m/z 319.013045.
MCF7 cells were treated with compounds or vehicle
(DMSO). After a 48 h incubation, the SRB assay was
used to determine inhibition of proliferation and
cytoxicity.24 Percent inhibition of growth at 100 mM was
determined and GI50 values were calculated from log-
dose response curves as previously described.16
4.29. 4-[4-(30,40-Dichloro-phenylsulfanyl)-phenyl]-thiazol-
2-yl ammonium iodide (28)
Isolated as a red solid (0.23 g, 48%); mp 45–47 ꢀC
(dec.); 1H NMR (DMSO-d6) d 7.18 (s, 1H), 7.24 (s, 2H),
7.46 (d, J=8.1 Hz, 2H), 7.59 (s, 1H), 7.69 (d, J=7.7 Hz,
2H); 13C NMR d 104.8, 128.1, 131.2, 131.3, 132.2,
132.6, 132.8, 133.0, 133.2, 140.1, 150.3, 161.2, 171.1;
HRMS calcd for C15H11Cl2IN2S2 (M-HI)+ m/z
352.974100, found m/z 352.974073.
Acknowledgements
We thank the National Cancer Institute’s Develop-
mental Therapeutics Program for testing the thiazoles,
the Leukemia and Lymphoma Society for funding, the
Leukemia and Lymphoma Society for funding, the
William Randolph Hearst Foundation for funding to
SLM, the University of Virginia Department of Chemistry,
and the Burger Center of Biological Sciences for support.
4.30. 4-[4-(40-Methoxy-phenylsulfanyl)-phenyl]-thiazol-2-
yl ammonium iodide (29)
Isolated as an orange solid (0.40 g, 91%); mp 202–
ꢀ
1
205 C; H NMR (DMSO-d6) d 3.74 (s, 3H), 6.98 (d,
J=8.3 Hz, 2H), 7.07 (s, 1H), 7.12 (d, J=7.9 Hz, 2H),
7.40 (d, J=8.1 Hz, 2H), 7.57 (d, J=7.7 Hz, 2H); 13C
NMR d 56.3, 103.4, 116.5, 116.7, 127.5, 128.4, 136.7,
140.3, 148.9, 154.3, 158.7, 169.7; MS APCI m/z 315 (M-
HI)+. Anal. calcd for C16H15IN2OS2: C, 43.44; H, 3.42;
N, 6.33. Found: C, 43.18; H, 3.40; N, 6.32.
References and notes
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4.31. 4-(40-p-Tolylsulfanyl-phenyl)-thiazol-2-yl ammo-
nium iodide (30)
Isolated as an orange solid (0.23 g, 54%); mp 182–
185 ꢀC; H NMR (DMSO-d6) d 2.28 (s, 3H), 7.08 (s,
1
1H), 7.20 (m, 2H), 7.28 (d, J=7.5 Hz, 2H), 7.62 (d,
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Results for each test agent were reported as the percent
of growth of the treated cells when compared to the
untreated control cells. Compounds which reduce
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passed on for evaluation in the full panel of 60 cell lines
over a 5-log dose range.
4.33. NCI Anti-tumor screen23
Compounds were tested, in duplicate, against 60 human
tumor cell lines at a minimum of five concentrations at

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