Efficient synthesis and biological evaluation of 1,3-benzenedicarbonyl dithioureas

Article abstract of DOI:10.1016/j.bmcl.2010.12.130

The synthesis and biological activity of 1,3-benzenedicarbonyl dithioureas are described. Bioassay results indicated that these compounds exhibited cytotoxicity against various cancer cells. For example, compounds 4a showed the best inhibition activities against KB and CNE2 with IC₅₀ 10.72 and 9.91 μM, respectively.

Full text of DOI:10.1016/j.bmcl.2010.12.130

Bioorganic & Medicinal Chemistry Letters 21 (2011) 1102–1104
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Efficient synthesis and biological evaluation of 1,3-benzenedicarbonyl
dithioureas
Hao Peng a, Yongju Liang b, Le Chen a, Liwu Fu b, , Haiqin Wang a, Hongwu He a,
⇑
⇑
a Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, and College of Chemistry, Central China Normal University, Wuhan 430079, PR China
b State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, Guangzhou 510060, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
The synthesis and biological activity of 1,3-benzenedicarbonyl dithioureas are described. Bioassay results
indicated that these compounds exhibited cytotoxicity against various cancer cells. For example, com-
pounds 4a showed the best inhibition activities against KB and CNE2 with IC50 10.72 and 9.91 lM,
Received 29 September 2010
Revised 23 December 2010
Accepted 28 December 2010
Available online 1 January 2011
respectively.
Ó 2010 Elsevier Ltd. All rights reserved.
Keywords:
Synthesis
Antitumor activity
1,3-Benzenedicarbonyl dithioureas
Acylthioureas (ATUs) possess various biological activities,
such as antiviral,1,2 antibacterial,3 fungicidal,4,5 herbicidal,6,7 plant
growth regulating,8 antiaggregating,9 antiarrythmic,10 analgesic,10
antihyperlipidemic,10 local anesthetic.10 Especially some thieno[3,
2-b]pyridine acylthioureas have been recently described as potent
antitumor agents inhibiting c-Met/VEGFR2 tyrosine kinase11 and
some quinoline and quinazoline–acylthiourea derivatives have
been reported as potent and selective inhibitors of the platelet-
derived growth factor (PDGF) receptor autophosphorylation.12
In the past, the pharmacological potential of this chemical class
had attracted our attention and a number of ATUs endowed with
various biological activities have been synthesized in our group.13
Recently, we have become interested in the synthesis of symmetric
acylthioureas aiming to finding novel antitumor agents. Herein, we
would like to describe an efficient synthesis and antitumor activi-
ties of 1,3-benzenedicarbonyl dithiourea 4 from easily accessible
1,3-benzenedicarbonyl diisothiocyanate 3.
All of the compounds studied in this work were synthesized
according to the similar methods described in the literature,14,15
in which compounds 4b, 4g, 4j, 4m and 4n have been reported.
The isophthaloyl dichloride 2, obtained by reaction of isophthalic
acid 1 with sulfuryl dichloride and N,N-dimethylformamide, was
converted easily to 1,3-benzenedicarbonyl diisothiocyanate 3 via
reaction with ammonium thiocyanate by solid–liquid phase
transfer catalysis of polyethylene glycol-400 (PEG-400). 1,3-Ben-
benzeneamine to give 1,3-benzenedicarbonyl dithiourea 4 in
satisfactory yields at room temperature.16 The results are listed
in Table 1.
NH4SCN,PEG-400
CH2Cl2
HO
OH
SOCl2/DMF
Cl
Cl
O
O
O
O
O
O
S
1
2
R
H
N
H
N
H
N
H
N
NH2
CH2Cl2
S
S
N
N
C
C
R
R
O
O
S
3
4
All the compounds of the 4 series were obtained as white or yel-
low solids after recrystallization from DMF/H2O. Their structures
were fully characterized by IR, 1H NMR, EI-MS and elemental anal-
ysis. For example, the IR spectrum of 4a revealed absorption bands
at 1671 (C@O), 3045 (C6H5), and 3217 (NH) cmÀ1. The correspond-
ing 1H NMR spectrum showed the OH group at d(H) 10.27 (s), and
the NH signals of the thiourea appeared at d(H) 11.47 and 12.90.
The other signals resonated at d(H) 6.80–8.53 (m, 12 Ar-H). The
structures of 4a and the other analogs were further confirmed on
the basis of elemental analysis. In the case of 5n, single-crystal
X-ray diffraction was employed to confirm the structure.17
zenedicarbonyl diisothiocyanate
3 reacted with substituted
The biological activity of the series of compounds 4 was inves-
tigated, and the results showed that most of them exhibited good
to moderate cytotoxicity against KB and CNE2 cancer cell lines.18
Compounds 4a (R = 2-OH) showed the best inhibitory activity
⇑
Corresponding authors. Tel./fax: +86 27 67867960.
E-mail addresses: fulw@mail.sysu.edu.cn (L. Fu), he1208@mail.ccnu.edu.cn (H.
He).
0960-894X/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2010.12.130

H. Peng et al. / Bioorg. Med. Chem. Lett. 21 (2011) 1102–1104
1103
Table 1
References and notes
a
Yields and in vitro cytotoxicity (IC50 , lM) of 1,3-benzenedicarbonyl dithiourea 4
1. Sun, J. Y.; Cai, S. X.; Mei, H.; Li, J.; Yan, N.; Wang, Q.; Lin, Z. H.; Huo, D. Q. Chem.
Biol. Drug Des. 2010, 76, 245.
2. Sun, C. W.; Zhang, X. D.; Huang, H.; Zhou, P. Bioorg. Med. Chem. 2006, 14,
8574.
3. Zhong, Z. M.; Xing, R.; Liu, S.; Wang, L.; Cai, S. B.; Li, P. C. Carbohydr. Res. 2008,
343, 566.
4. Wang, F. H.; Qin, Z. L.; Huang, Q. Front. Chem. Chin. 2006, 1, 112.
5. Ke, S. Y.; Xue, S. J. Arkivoc 2006, x, 63.
6. Xue, S. J.; Ke, S. Y.; Wei, T. B.; Duan, L. P.; Guo, Y. L. J. Chin. Chem. Soc. 2004, 51,
1013.
7. Xiao, L.; Liu, C. J.; Li, Y. P. Molecules 2009, 14, 1423.
8. Hua, J. H.; Wang, L. C.; Liu, H.; Wei, T. B. Phosphorus Sulfur 2006, 181, 2691.
9. Ranise, A.; Bondavalli, F.; Bruno, O.; Schenone, S.; Donnoli, D.; Parrillo, C.;
Cenicola, M. L.; Rossi, F. Farmaco 1991, 46, 1203.
10. Ranise, A.; Spallarossa, A.; Bruno, O.; Schenone, S.; Fossa, P.; Menozzi, G.;
Bondavalli, F.; Mosti, L.; Capuano, A.; Mazzeo, F.; Falcone, G.; Filippelli, W.
Farmaco 2003, 58, 765.
11. Claridge, S.; Raeppel, F.; Granger, M. C.; Bernstein, N.; Saavedra, O.; Zhan, L.;
Llewellyn, D.; Wahhab, A.; Deziel, R.; Rahil, J.; Beaulieu, N.; Nguyen, H.;
Dupont, I.; Barsalou, A.; Beaulieu, C.; Chute, I.; Gravel, S.; Robert, M. F.;
Lefebvre, S.; Dubay, M.; Pascal, R.; Gillespie, J.; Jin, Z.; Wang, J.; Besterman, J.
M.; MacLeod, A. R.; Vaisburg, A. Bioorg. Med. Chem. Lett. 2008, 18, 2793.
12. Furuta, T.; Sakai, T.; Senga, T.; Osawa, T.; Kubo, K.; Shimizu, T.; Suzuki, R.;
Yoshino, T.; Endo, M.; Miwa, A. J. Med. Chem. 2006, 49, 2186.
13. Peng, H.; He, H. W. Chin. J. Org. Chem. 2007, 27, 502.
14. Duan, Z. F.; Gu, L. Q.; Huang, Z. S.; Xie, W. L.; Ma, L. Chin. J. Appl. Chem. 2003, 20, 80.
15. Wei, W.; Cao, C.; Zhang, Y. M.; Wei, T. B. Asian J. Chem. 2007, 19, 1951.
Compd
R
Yieldb (%)
Cytotoxicity
against KBc
Cytotoxicity
against CNE2c
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
2-OH
2-Cl
2-Br
2-F
2-CF3
2-CH3
3-Cl
3-Br
4-OH
4-Cl
4-Br
4-F
4-CH3
4-NO2
4-OCH3
H
83
72
74
69
76
60
82
81
89
69
81
71
78
73
78
88
10.72
38.75
47.1
44.95
26.05
>50
12.02
15.16
20
13.70
23.17
43.2
15.32
35.7
>50
>50
15.9
9.91
>50
>50
38.56
18.50
>50
16.27
18.56
16.61
15.72
32.66
32.97
32.98
>50
30.34
>50
Fluorouracil
a
IC50 is the concentration of compound required to inhibit the cell growth by 50%
compared to an untreated control.
Isolated yields based on 1,3-benzenedicarbonyl diisothiocyanate 3.
KB cells were the drug sensitive human oral carcinoma cells and CNE2 cells
were the nasopharyngeal carcinoma cells.
b
c
16. Preparation of 1,3-benzenedicarbonyl dithiourea 4:
A suspension of 1,3-
benzenedicarbonyl chloride (1.02 g, 5 mmol), ammonium thiocyanate (1.14 g,
15 mmol) and PEG-400 (3% based on ammonium thiocyanate) in methylene
chloride was stirred for 2 h at room temperature. The reaction mixture was
filtered to give the soln of 3, which was used directly without further
purification. To a soln of 3 in CH2Cl2 (10 ml), the appropriate benzeneamine
was added and the mixture was stirred for another 1 h, the yellow precipitate
was formed. The reaction mixture was filtered and washed with a small
quantity of ethanol, Et2O and water successively, then recrystallized from
DMF-water to give the target compounds.
against KB and CNE2 with IC50 10.72 and 9.91 lM, respectively, the
inhibitory activity against KB even higher than that of fluorouracil
(Table 1), while its unsubstituted analog 4p showed no effect in
inhibitory activity. Replacement of hydroxyl group in compound
4a with chloro (4b, IC50 = 38.75
against KB by three-fold. The analogs 4c (IC50 = 47.10
(IC50 = 44.95 M), with halo substitution in the benzene ring, show
lM) reduced the cytotoxicity
Compound 4a. Yellow solid. mp 201–203 °C. IR(KBr)
t: 3408, 3217, 3045,
lM) and 4d
1671(C@O), 1607, 1539, 1459, 1356 cmÀ1 1H NMR (600 MHz DMSO-d6)
.
l
d(ppm): 6.80–8.53 (m, 12H, Ar-H), 10.27 (s, 2H, OH), 11.47 (s, 2H, NH), 12.90
(s, 2H, NH). MS (70 eV) m/z (%): 466 (M+). Anal. Calcd for C22H18N4O4S2: C,
56.64; H, 3.89; N, 12.01. Found: C, 56.91; H, 3.41; N, 12.47.
reduction in the inhibitory activity by 4–5-fold as compared to 4a.
In the case of halo substituted derivatives, the compounds 4g and
4h, with halo substitution at meta position in benzene ring showed
better activity compared to that substituted at ortho (4b and 4c)
and para (4j and 4k) position. Replacement of R hydroxyl group
with methyl group showed marginal reduction in the inhibitory
activity as can be seen by comparing the IC50 values of compound
Compound 4b. Yellow solid. mp 185–187 °C. IR(KBr)
t
.
: 3370, 3232, 2960,
1673(C@O), 1591, 1547, 1524, 1463, 1442, 1341 cmÀ1
1H NMR (600 MHz
DMSO-d6) d(ppm): 7.34–8.66 (m, 12H, Ar-H), 11.86 (s, 2H, NH), 12.61 (s, 2H,
NH). MS (70 eV) m/z (%): 502 (M+). Anal. Calcd for C22H16Cl2N4O2S2: C, 52.49; H,
3.20; N, 11.13. Found: C, 52.11; H, 2.83; N, 11.56.
Compound 4c. Yellow solid. mp 191–193 °C. IR(KBr)
t
.
: 3433, 3200, 3010,
1695(C@O), 1590, 1520, 1516, 1472, 1426, 1367 cmÀ1
1H NMR (600 MHz
DMSO-d6) d(ppm): 7.26–8.64 (m, 12H, Ar-H), 11.86 (s, 2H, NH), 12.50 (s, 2H,
NH). MS (70 eV) m/z (%): 590 (M+). Anal. Calcd for C22H16Br2N4O2S2: C, 44.61;
H, 2.72; N, 9.46. Found: C, 44.94; H, 2.25; N, 9.02.
4a with 4f (IC50 >50 lM). Compound 4i with R hydroxyl group at
para position in benzene ring showed two-fold decreases in po-
tency, compared to 4a with hydroxyl group at ortho position.
And introduction bulk groups like nitro and methoxy at para posi-
tion in benzene ring, resulted in the compounds 4n and 4o with
marginal reduction or no inhibitory activity. Furthermore, some
1,4-benzenedicarbonyl dithioureas were also synthesized, but
their cytotoxicity showed almost inactive, for example, the corre-
sponding 1,4-benzenedicarbonyl dithiourea of compound 4a
(R = 2-OH) showed no inhibitory activity against KB and CNE2 with
Compound 4d. Yellow solid. mp 192–194 °C. IR(KBr)
t: 3386, 3023, 1683(C@O),
1618, 1598, 1557, 1527, 1483, 1459, 1354 cmÀ1 1H NMR (600 MHz DMSO-d6)
.
d(ppm): 7.26–8.61 (m, 12H, Ar-H), 11.80 (s, 2H, NH), 12.47 (s, 2H, NH). MS
(70 eV) m/z (%): 470 (M+). Anal. Calcd for C22H16F2N4O2S2: C, 56.16; H, 3.43; N,
11.91. Found: C, 55.70; H, 3.51; N, 11.54.
Compound 4e. Yellow solid. mp 194–196 °C. IR(KBr)
t
.
: 3417, 3246, 3040,
1681(C@O), 1603, 1559, 1527, 1414, 1350, 1323 cmÀ1
1H NMR (600 MHz
DMSO-d6) d(ppm): 7.71–8.57 (m, 12H, Ar-H), 11.70 (s, 2H, NH), 12.65 (s, 2H,
NH). MS (70 eV) m/z (%): 570 (M+). Anal. Calcd for C24H16F6N4O2S2: C, 50.52; H,
2.83; N, 9.82. Found: C, 50.26; H, 2.62; N, 9.52.
Compound 4f. Yellow solid. mp 183–185 °C. IR(KBr)
t: 3315, 3171, 3027,
IC50 more than 50 lM.
1675(C@O), 1611, 1588, 1521,1458, 1352 cmÀ1 1H NMR (600 MHz DMSO-d6)
.
In conclusion, we have synthesized a series of 1,3-benzenedi-
carbonyl dithiourea via reaction of functionalized diisothiocyanate
with various benzeneamine. The preliminary investigation on the
biological activities of 4 showed that some of them exhibited cyto-
toxicity against various cancer cells.
d(ppm): 2.27 (s, 6H, CH3), 7.22–8.62 (m, 12H, Ar-H), 11.64 (s, 2H, NH), 12.23 (s,
2H, NH). MS (70 eV) m/z (%): 462 (M+). Anal. Calcd for C24H22N4O2S2: C, 62.31;
H, 4.79; N, 12.11. Found: C, 61.85; H, 4.70; N, 11.75.
Compound 4g. Yellow solid. mp 189–191 °C. IR(KBr)
t: 3417, 3227, 3156, 3046,
1678(C@O), 1589, 1538, 1432, 1333, 1303 cmÀ1 1H NMR (600 MHz DMSO-d6)
.
d(ppm): 7.37–8.58 (m, 12H, Ar-H), 11.68 (s, 2H, NH), 12.54 (s, 2H, NH). MS
(70 eV) m/z (%): 502 (M+). Anal. Calcd for C22H16Cl2N4O2S2: C, 52.49; H, 3.20;
N,11.13. Found: C, 52.79; H, 3.32; N, 11.17.
Compound 4h. White solid. mp 190–192 °C. IR(KBr)
t
.
: 3433, 3221, 3032,
Acknowledgments
1680(C@O), 1588, 1534, 1516, 1472, 1426, 1349 cmÀ1
1H NMR (600 MHz
DMSO-d6) d(ppm): 7.39–8.57 (m, 12H, Ar-H), 11.67 (s, 2H, NH), 12.53 (s, 2H,
NH). MS (70 eV) m/z (%): 590 (M+). Anal. Calcd for C22H16Br2N4O2S2: C, 44.61;
H, 2.72; N, 9.46. Found: C, 44.71; H,2.69; N,9.75.
We gratefully acknowledge financial support of this work by
the National Basic Research Program of China (2010CB126100),
the National Natural Science Foundation of China (Nos. 20772042
and 21002037) and the Opening Foundation of the Key Laboratory
of Green Pesticide and Agricultural Bioengineering, Ministry of
Education, Guizhou University (grant No. 2009GDGP0101). The
research was supported in part by the PCSIRT (No. IRT0953).
Compound 4i. Yellow solid. mp 190–192 °C. IR(KBr)
t: 3321, 1670(C@O), 1613,
1515, 1438, 1345 cmÀ1 1H NMR (600 MHz DMSO-d6) d(ppm): 6.78–8.52 (m,
.
12H, Ar-H), 9.58–9.59 (d, 2H, OH), 11.46 (s, 2H, NH), 12.33 (s, 2H, NH). MS
(70 eV) m/z (%): 466 (M+). Anal. Calcd for C22H18N4O4S2: C, 56.64; H, 3.89; N,
12.01. Found: C, 56.77; H, 3.41; N, 12.47.
Compound 4j. Yellow solid. mp 212–214 °C. IR(KBr)
t
: 3437, 3204, 3021,
1671(C@O), 1643, 1587, 1548, 1522, 1491, 1433, 1400, 1382, 1344 cmÀ1
.
1H

1104
H. Peng et al. / Bioorg. Med. Chem. Lett. 21 (2011) 1102–1104
NMR (600 MHz DMSO-d6) d(ppm): 7.48–8.55 (m, 12H, Ar-H), 11.62 (s, 2H, NH),
12.47 (s, 2H, NH). MS (70 eV) m/z (%): 502 (M+). Anal. Calcd for
22H16Cl2N4O2S2: C, 52.49; H, 3.20; N, 11.13. Found: C, 52.55; H, 3.26; N, 11.17.
Compound 4k. Yellow solid. mp 202–204 °C. IR(KBr) : 3324, 3027, 2923,
1680(C@O), 1591, 1552, 1515, 1485, 1346 cmÀ1 1H NMR (600 MHz DMSO-d6)
(m, 12H, Ar-H), 11.80 (s, 2H, NH), 12.78 (s, 2H, NH). MS (70 eV) m/z (%): 525
(M++1). Anal. Calcd for C22H16N6O6S2: C, 50.38; H, 3.07; N, 16.02. Found: C,
50.40; H, 3.15; N, 16.33.
C
t
Compound 4o. Yellow solid. mp 186–188 °C. IR(KBr)
t: 3377, 3189, 2963,
.
1669(C@O), 1608, 1515, 1330 cmÀ1 1H NMR (600 MHz DMSO-d6) d(ppm): 3.77
.
d(ppm): 7.64–8.57 (m, 12H, Ar-H), 11.64 (s, 2H, NH), 12.49 (s, 2H, NH). MS
(70 eV) m/z (%): 590 (M+). Anal. Calcd for C22H16Br2N4O2S2: C, 44.61; H, 2.72; N,
9.46. Found: C, 44.94; H, 2.35; N, 9.92.
(s, 6H, OCH3), 6.97–8.54 (m, 12H, Ar-H), 11.50 (s, 2H, NH), 12.38 (s, 2H, NH). MS
(70 eV) m/z (%): 494 (M+). Anal. Calcd for C24H22N4O4S2: C, 58.28; H, 4.48; N,
11.33. Found: C, 58.64; H, 4.68; N, 11.47.
Compound 4l. Yellow solid. mp 196–197 °C. IR(KBr)
t
: 3151, 3042, 1680(C@O),
Compound 4p. Yellow solid. mp 190–192 °C. IR(KBr)
t: 3443, 3332, 3169, 3033,
1654, 1612, 1551, 1507, 1438, 1355, 1319 cmÀ1 1H NMR (600 MHz DMSO-d6)
.
1671(C@O), 1598, 1555, 1516, 1447, 1349 cmÀ1 1H NMR (600 MHz DMSO-d6)
.
d(ppm): 7.25–8.55 (m, 12H, Ar-H), 11.59 (s, 2H, NH), 12.41 (s, 2H, NH). MS
(70 eV) m/z (%): 470 (M+). Anal. Calcd for C22H16F2N4O2S2: C, 56.16; H, 3.43; N,
11.91. Found: C, 55.78; H, 3.02; N, 11.90.
d(ppm): 7.27–8.56 (m, 12H, Ar-H), 11.57 (s, 2H, NH), 12.53 (s, 2H, NH). MS
(70 eV) m/z (%): 434 (M+). Anal. Calcd for C22H18N4O2S2: C, 60.81; H, 4.18; N,
12.89. Found: C, 60.83; H, 3.95; N, 12.99.
Compound 4m. Yellow solid. mp 210–212 °C. IR(KBr)
t
: 3410, 3164, 3030,
17. Crystallographic data for the structural analysis have been deposited at the
Cambridge Crystallographic Data Centre, CCDC No 802615. (E-mail:
deposit@ccdc.cam.ac.uk).
18. Cytotoxic activities were evaluated by using standard MTT assay after
exposure of cells to the tested compounds for 72 h. Results are presented as
mean values of three independent experiments done in quadruplicates.
Coefficients of variation were <10%.
1675(C@O), 1596, 1531, 1361, 1343 cmÀ1 1H NMR (600 MHz DMSO-d6)
.
d(ppm): 2.31 (s, 6H, CH3), 7.20–8.54 (m, 12H, Ar-H), 11.52 (s, 2H, NH), 12.47
(s, 2H, NH). MS (70 eV) m/z (%): 462 (M+). Anal. Calcd for C24H22N4O2S2: C,
62.31; H, 4.79; N, 12.11. Found: C, 62.19; H, 4.52; N, 11.86.
Compound 4n. Yellow solid. mp 210–212 °C. IR(KBr)
t: 3247, 3007, 1679(C@O),
1614, 1565, 1514, 1320 cmÀ1 1H NMR (600 MHz DMSO-d6) d(ppm): 7.76–8.59
.