Design, synthesis, and biological evaluation of new series of 2-amido-1,3,4-thiadiazole derivatives as cytotoxic agents

Article abstract of DOI:10.1515/znb-2015-0138

A series of novel 1,3,4-thiadiazole derivatives bearing an amide moiety were designed, synthesized, and evaluated for their in vitro antitumor activities against HL-60, SKOV-3 and MOLT-4 human tumor cell lines by MTT assay. Ethyl 2-((5-(4-methoxybenzamido)-1,3,4-thiadiazol- 2-yl)thio)acetate (5f) showed the best inhibitory effect against SKOV-3 cells, with an IC50 value of 19.5 μm. In addition, the acridine orange/ethidium bromide staining assay in SKOV-3 cells suggested that the cytotoxic activity of 5f occurs via apoptosis.

Full text of DOI:10.1515/znb-2015-0138

Z. Naturforsch. 2016; aop
Ali Almasirad, Loghman Firoozpour, Maliheh Nejati, Najmeh Edraki, Omidreza Firuzi,
Mehdi Khoshneviszadeh, Mohammad Mahdavi, Setareh Moghimi, Maliheh Safavi,
Abbas Shafiee and Alireza Foroumadi*
Design, synthesis, and biological evaluation
of new series of 2-amido-1,3,4-thiadiazole
derivatives as cytotoxic agents
DOI 10.1515/znb-2015-0138
Received August 18, 2015; accepted December 18, 2015
1 Introduction
Abstract: A series of novel 1,3,4-thiadiazole derivatives Cancer has been proposed as the most serious health
bearing an amide moiety were designed, synthesized, problem all over the world and is the leading cause of
and evaluated for their in vitro antitumor activities against death in humans [1]. During the last few decades, more
HL-60, SKOV-3 and MOLT-4 human tumor cell lines by than 70 % of all cancer deaths occurred in developing and
MTT assay. Ethyl 2-((5-(4-methoxybenzamido)-1,3,4-thi- underdeveloped countries [2]. Chemotherapy, one of the
adiazol-2-yl)thio)acetate (5f) showed the best inhibitory main treatment methods, is accompanied by complicated
effect against SKOV-3 cells, with an IC50 value of 19.5 μm. In systemic toxicity, serious side effects, high mortality rate,
addition, the acridine orange/ethidium bromide staining high costs, and development of resistant strains [3]. There-
assay in SKOV-3 cells suggested that the cytotoxic activity fore, the development of novel chemical structures with
of 5f occurs via apoptosis.
high efficacy, low toxicity, a minimum of undesirable side
effects, and acceptable resistance profiles is eagerly being
pursued [4].
Keywords: antitumor agent; cancer; cytotoxic activity;
fluorescence; thiadiazole.
The 1,3,4-thiadiazole ring system is characterized as
an important heterocyclic core playing a significant role in
medicinal chemistry, especially in the field of antimicrobial
agents and chemotherapy [5]. 1,3,4-Thiadiazole derivatives
exhibit a broad spectrum of interesting pharmacological
properties like antileishmanial, antioxidant, anti-Helico-
bacter pylori, fungicidal, antitubercular, anticancer, anti-
inflammatory, antiviral, and anticonvulsant [6–23].
High-throughput screening at Bristol–Myers Squibb
revealed (2-acetamido-thiazolyl) thioacetic ester 1 as an
inhibitor of cyclin-dependent kinase 2 (CDK2) (Fig. 1) [24].
Moreover, 2-amino-1,3,4-thiadiazole derivatives were also
introduced as potential anticancer agents; as shown in
Fig. 1, compounds 2 and 3, with this effective core struc-
ture, exhibited good inhibitory activities against Akt/
protein kinase B (PKB) [25, 26].
Recently, Zhang et al. reported the antiproliferative
properties of novel hybrid molecules containing 1,3,4-oxa-
diazole and 1,3,4-thiadiazole moieties exemplified by
compound 4 in Fig. 1 [27]. According to the above-men-
tioned findings and in continuation of our interests in
exploration of novel heterocyclic scaffolds with antican-
cer activities [28–31], herein we describe a new series of
1,3,4-thiadiazole derivatives 5a–n, which were designed
by replacing the thiazole with a thiadiazole ring and the
*Corresponding author: Alireza Foroumadi, Drug Design and
Development Research Center, Tehran University of Medical
Sciences, Tehran, I. R. Iran; and Department of Medicinal Chemistry,
Faculty of Pharmacy and Pharmaceutical Sciences Research Center,
Tehran University of Medical Sciences, Tehran, I. R. Iran,
Fax: +98-21-66461178, E-mail: aforoumadi@yahoo.com
Ali Almasirad: Department of Medicinal Chemistry, Faculty
of Pharmacy, Pharmaceutical Sciences Branch, Islamic Azad
University, Tehran, I. R. Iran
Loghman Firoozpour and Maliheh Nejati: Drug Design and
Development Research Center, Tehran University of Medical
Sciences, Tehran, I. R. Iran
Najmeh Edraki, Omidreza Firuzi and Mehdi Khoshneviszadeh:
Medicinal and Natural Products Chemistry Research Center,
Shiraz University of Medical Sciences, Shiraz, I. R. Iran
Mohammad Mahdavi, Setareh Moghimi and Abbas Shafiee:
Department of Medicinal Chemistry, Faculty of Pharmacy and
Pharmaceutical Sciences Research Center, Tehran University of
Medical Sciences, Tehran, I. R. Iran
Maliheh Safavi: Department of Biotechnology, Iranian Research
Organization for Science and Technology, Tehran, I. R. Iran
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ꢀꢀꢀꢁ
2ꢀ
ꢀA. Almasirad et al.: New 2-amido-1,3,4-thiadiazole derivatives as cytotoxic agents
N
N
NH
H
S
O
N
H
COOC2
S
5
S
HO
OH
H
3C
N
N
F
1
2
HO
N
N
S
N
NH
N
C
S
H
O
Cl
HO
OH
N
R
N
Cl
3
4
H
COOC2
N
S
5
N
O
S
N
H
X
5
Fig. 1:ꢀCompounds 1–4 with 2,5-disubstituted 1,3,4-thiadiazole and thiazole structures were reported as cytotoxic agents. Compounds
5a–n (see Scheme 1 and Table 1) were designed as new potential cytotoxic agents.
S
methyl group with substituted phenyl moieties in com-
pound 1 to achieve better cytotoxic effects.
+
CS2
H2N
N
NH2
i
H
2 Results and discussion
O
N
N
N
N
O
ii
+
Br
Cl
NH2
HS
NH2
S
OEt
S
6
S
2.1 Chemistry
O
7
8
O
O
The target compounds 5a–n were prepared via the syn-
thetic route illustrated in Scheme 1. First, 5-amino-1,3,4-
thiadiazole-2-thiol (6) was prepared via the reaction of
thiosemicarbazide and CS2 in EtOH at reflux temperature
[32]. Then, 6 was converted to ethyl 2-((5-amino-1,3,4-thi-
adiazol-2-yl)thio)acetate (8) by the action of ethyl 2-bro-
moacetate in the presence of potassium hydroxide [33]. In
the next step, 8 was reacted with the corresponding aroyl
chlorides in the presence of Et3N at ambient temperature
to afford target compounds 5a–n.
N N
S
O
iii
+
8
Ar
N
S
Ar
H
O
5a–n
9a–n
Scheme 1:ꢀSynthesis of compounds 5a–n (for substituent Ar, see
Table 1). Reagents and conditions: (i) Na2CO3, EtOH, reflux; (ii) KOH,
EtOH, r.t.; (iii) Et3N, THF, reflux. For the syntheses of 6 and 8, see
references [32] and [33], respectively.
dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)
assay against HL-60 (human promyelocytic leukemia),
SKOV-3 (human ovarian carcinoma), and MOLT-4 (human
acute lymphoblastic leukemia) cell lines [28].
The results of cytotoxic data indicated that all synthe-
sized (2-amido-thiadiazolyl)acetic ester derivatives 5a–n
2.2 Pharmacology
2.2.1 Cytotoxic assay
The in vitro effect of synthesized compounds 5a–n on possess lower cytotoxic potential than doxorubicin and
cancer cell viability was assessed using MTT (3-(4,5- cisplatin in all three cell lines. Moreover, these compounds
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A. Almasirad et al.: New 2-amido-1,3,4-thiadiazole derivatives as cytotoxic agentsꢂ ꢂ3
were inactive against the MOLT-4 cell line, which could be 4. Replacement of the phenyl moiety with other five-
attributed to rapid hydrolysis of the compounds.
Compound 5f was the most potent compound against
SKOV-3 and HL-60 cell lines with IC50 values of 19.5 and
membered heterocyclic rings, such as furan and thio-
phene, leads to a reduced cytotoxic activity.
30.1 μm, respectively. In case of the SKOV-3 cell line, com- The acridine orange (AO)/ethidium bromide (EB) double
pounds 5c and 5h exhibited the highest growth inhibitory staining technique was used to evaluate the occurrence of
activities at concentrations of 26.3 and 22.2 μm, respec- apoptosis in SKOV-3 cells, which had been treated with 5a.
tively. Compounds 5a, 5c, and 5h showed inhibitory effects AO, a nucleic acid fluorescent cationic dye, permeates all
on viability of HL-60 cells at concentrations ꢀ<ꢀ35 μm. As cells and makes the nuclei appear green. EB is only taken
can be seen in Table 1, 5n showed no growth-inhibiting up by cells when cytoplasmic membrane integrity is lost,
potential on cancer cell lines within the tested concentra- and then stains the nucleus red. Analysis of the AO/EB
tions. According to the obtained data (Table 1), the follow- staining revealed that compound 5f induced apoptosis in
ing structure-activity relationship could be constructed:
the SKOV-3 cell line. As shown in Fig. 2, the non-apoptotic
1. The presence of an electron-withdrawing group control cells were stained green, and the late apoptotic
diminishes the cytotoxic activity of the synthesized cells incorporate EB, thus staining orange, and show con-
compounds.
densed and fragmented nuclei.
2. Introduction of different substituents such as chlo-
rine, methoxy, and methyl groups into the ortho posi-
tion of the phenyl moiety decreases the cytotoxic
potential of the thiadiazole derivatives.
3. Substitution of different groups such as chlorine,
methoxy, and methyl at the meta and para positions
of the phenyl moiety potentiates the anticancer activ-
ity of the studied compounds.
3 Conclusion
A novel series of ethyl 2-((5-(benzamido)-1,3,4-thiadiazol-
2-yl)thio)acetates 5a–n were synthesized with an objec-
tive to study their antitumor activities. The designed
compounds showed good antiproliferative activities
against different cell lines. Some tested compounds
including 5c, 5f, and 5h exhibited cytotoxic activities
against SKOV-3 and HL-60. Meanwhile, all compounds
were inactive against the MOLT-4 cell line, probably due
to the rapid hydrolysis of these compounds. The results of
an AO/EB staining assay of compound 5f suggested that
the cytotoxic activity of this compound against SKOV-3
cell line occurs via apoptosis. These results are therefore
conclusive in showing that different benzamide moieties
attached to the 1,3,4-thiadiazole core make some of them
lead molecules for further optimization in the develop-
ment of a novel anticancer agent.
Table 1:ꢀCell growth inhibitory activity of synthetic compounds
5a–n assessed by the MTT reduction assay.
O
O
N N
N
Ar
S
S
H
O
Compound ꢁ Ar
ꢁ
ꢁ
IC50 (μm)a
HL-60 cellsꢁ SKOV-3 cellsꢁ MOLT-4 cells
5a
ꢃ
C6H5
ꢃ
ꢃ
ꢃ
32.4 4.2ꢃ
ꢃ>ꢃ100ꢃ 59.8 19.9ꢃ
30.8 6.4ꢃ 26.3 5.0ꢃ
27.2 3.0ꢃ
ꢃ>ꢃ100
ꢃ>ꢃ100
ꢃ>ꢃ100
ꢃ>ꢃ100
ꢃ>ꢃ100
ꢃ>ꢃ100
ꢃ>ꢃ100
ꢃ>ꢃ100
5b
ꢃ 2-MeC6H4
ꢃ 3-MeC6H4
5c
5d
ꢃ 4-MeC6H4 ꢃ 68.8 14.9ꢃ 45.4 13.2ꢃ
ꢃ 2-OMeC6H4 ꢃ 38.5 4.7ꢃ 42.3 11.9ꢃ
ꢃ 4-OMeC6H4 ꢃ 30.1 2.7ꢃ
5e
5f
19.5 2.1ꢃ
ꢃ>ꢃ100ꢃ 79.2 11.8ꢃ
4 Experimental section
5g
ꢃ 2-ClC6H4
ꢃ 2-ClC6H4
ꢃ 4-ClC6H4
ꢃ
ꢃ
ꢃ
5h
33.8 4.4ꢃ
88.6 10.8ꢃ
22.2 0.7ꢃ
45.0 5.1ꢃ
37.0 6.2ꢃ
34.5 4.4ꢃ
5i
ꢃ>ꢃ100 4.1 Procedure for the synthesis
5j
ꢃ 2,4-Cl2C6H4ꢃ 59.7 3.3ꢃ
ꢃ>ꢃ100
of compound 5a
5k
ꢃ 3-FC6H4
ꢃ 3-NO2C6H4
ꢃ 2-Thienyl
ꢃ 2-Furyl
–
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
45.3 9.2ꢃ
ꢃ>ꢃ100
5l
ꢃ>ꢃ100ꢃ 72.7 10.3ꢃ
ꢃ>ꢃ100
To a solution of compound 8 [33] (1 mmol, 0.22 g) in anhy-
5m
ꢃ>ꢃ100ꢃ
ꢃ>ꢃ100ꢃ
0.013
0.002
2.1 0.3ꢃ
75.1 6.3ꢃ
ꢃ>ꢃ100ꢃ
0.018
0.016
8.5 4.8ꢃ
ꢃ>ꢃ100
drous THF (10 mL) containing triethyl amine (1.5 mmol,
0.15 g), benzoyl chloride (1 mmol, 0.14 g) was added. The
reaction mixture was refluxed and monitored by TLC.
Upon completion, the reaction mixture was cooled, and
the precipitated solid was filtered off and recrystallized
from ethanol to give compound 5a.
5n
ꢃ>ꢃ100
Doxorubicinꢃ
ꢃ
ꢃ
0.047
0.015
Cisplatin
ꢃ
–
ꢃ
3.1 0.1
aValues represent mean SEM. When compounds were inactive, IC50
was reported as more than the maximum tested concentrations.
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4ꢀ ꢀA. Almasirad et al.: New 2-amido-1,3,4-thiadiazole derivatives as cytotoxic agents
Fig. 2:ꢀAO/EB double staining of SKOV-3 cells with characteristic symptoms of apoptosis: (a) DMSO 2 % as control and (b) cells treated with
IC50 concentration of compound 5f, respectively, for 24 h. The images of cells were taken with a fluorescence microscope at 400ꢃ×ꢃ.
4.1.1 Ethyl 2-((5-benzamido-1,3,4-thiadiazol-2-yl)thio)
acetate (5a)
8.20–8.60 (m, 1H), 12.68 (s, NH). – 13C NMR (100.0 MHz,
CDCl3, 25 °C, TMS): δ ppm ꢀ=ꢀ14.1 (CH3), 21.3 (SCH2), 35.6
(CH3), 62.1 (OCH2), 125.7 (CHAr), 128.7 (CHAr), 129.2 (CH2Ar),
Yield: 81 % (0.26 g). M.p. 174–176 °C. – IR (KBr): ν ꢀ=ꢀ 1726, 130.8 (CHAr), 134.2 (CH2Ar), 138.8 (CH2Ar), 158.5 (CH2Ar),
-1
1659 (Cꢀ=ꢀO) cm . – 1H NMR (400.0 MHz, CDCl3, 25 °C, TMS): 161.82 (CAr), 165.7 (Cꢀ=ꢀO), 168.0 (Cꢀ=ꢀO). – MS: m/z ꢀ=ꢀ 337
+
δ ppm ꢀ=ꢀ 1.26 (t, J ꢀ=ꢀ 7.2 Hz, 3H), 4.07 (s, 2H), 4.21 (q, J ꢀ=ꢀ [M] . – C14H15N3O3S2: anal. calcd. C 49.83, H 4.48, N 12.45;
7.2 Hz, 2H), 7.54–7.60 (m, 2H), 7.65 (dt, J ꢀ=ꢀ 7.2, 1.2 Hz, 1H), found C 49.57, H 4.17, N 12.72.
+
8.23–8.26 (m, 2H), 12.73 (s, NH). – MS: m/z ꢀ=ꢀ 323 [M] .
– C13H13N3O3S2: anal. calcd. C 48.28, H 4.05, N 12.99; found
C 48.55, H 4.21, N 12.66.
4.1.4 Ethyl 2-((5-(4-methylbenzamido)-1,3,4-thiadiazol-
2-yl)thio)acetate (5d)
4.1.2 Ethyl 2-((5-(2-methylbenzamido)-1,3,4-thiadiazol-
2-yl)thio)acetate (5b)
Yield: 72 % (0.24 g). M.p. 151–153 °C. – IR (KBr): ν ꢀ=ꢀ 1727,
-1
1654 (Cꢀ=ꢀO) cm . – 1H NMR (400.0 MHz, CDCl3, 25 °C, TMS):
δ ppm ꢀ=ꢀ 1.27 (t, J ꢀ=ꢀ 6.8 Hz, 3H), 2.49 (s, 3H), 4.09 (s, 2H),
Yield: 80 % (0.27 g). M.p. 150–152 °C. – IR (KBr): ν ꢀ=ꢀ 1727, 4.22 (q, J ꢀ=ꢀ 6.8 Hz, 2H), 7.36 (d, J ꢀ=ꢀ 7.8 Hz, 2H), 8.12 (d, J ꢀ=ꢀ
-1
1655 (Cꢀ=ꢀO) cm . – 1H NMR (400.0 MHz, CDCl3, 25 °C, TMS): 7.8 Hz, 2H), 12.42 (s, NH). – 13C NMR (100.0 MHz, CDCl3): δ
δ ppm ꢀ=ꢀ 1.31 (t, J ꢀ=ꢀ 7.2 Hz, 3H), 2.55 (s, 3H), 4.00 (s, 2H), ppm ꢀ=ꢀ 14.1 (CH3), 21.7 (SCH2), 35.4 (CH3), 62.1 (OCH2), 128.1
4.25 (q, J ꢀ=ꢀ 7.2 Hz, 2H), 7.31–7.38 (m, 2H), 7.47 (tt, J ꢀ=ꢀ 7.6, 1.2 (CHAr), 128.6 (CH2Ar), 129.5 (CH2Ar), 144.2 (CHAr), 158.4
H, 1H), 7.80 (dd, J ꢀ=ꢀ 7.7, 1.2 Hz, 1H), 12.48 (s, 1H). – 13C NMR (CAr), 161.6 (CAr), 165.8 (Cꢀ=ꢀO), 168.0 (Cꢀ=ꢀO). – MS: m/z ꢀ=ꢀ
+
(100.0 MHz, CDCl3, 25 °C, TMS): δ ppm ꢀ=ꢀ 14.1 (CH3), 21.4 337 [M] . – C14H15N3O3S2: anal. calcd. C 49.83, H 4.48, N
(SCH2), 35.1 (CH3), 62.1 (OCH2), 126.1 (CH2Ar), 128.5 (CH2Ar), 12.45; found C 49.57, H 4.29, N 12.77.
131.6 (CH2Ar), 131.7 (CH2Ar), 132.0 (CHAr), 138.3 (CHAr),
158.2 (CAr), 160.9 (CHAr), 167.2 (Cꢀ=ꢀO), 168.0 (Cꢀ=ꢀO). – MS:
4.1.5 Ethyl 2-((5-(2-methoxybenzamido)-1,3,4-
+
m/z ꢀ=ꢀ 337 [M] . – C14H15N3O3S2: anal. calcd. C 49.83, H 4.48,
thiadiazol-2-yl)thio)acetate (5e)
N 12.45; found C 49.56, H 4.37, N 12.74.
Yield: 84 % (0.29 g). M.p. 184–186 °C. – IR (KBr): ν ꢀ=ꢀ 1726,
-1
4.1.3 Ethyl 2-((5-(3-methylbenzamido)-1,3,4-thiadiazol-
2-yl)thio)acetate (5c)
1654 (Cꢀ=ꢀO) cm . – 1H NMR (400.0 MHz, CDCl3, 25 °C, TMS):
δ ppm ꢀ=ꢀ 1.26 (t, J ꢀ=ꢀ 7.2 Hz, 3H), 4.03 (s, 3H), 4.06 (s, 2H),
4.20 (q, J ꢀ=ꢀ 7.2 Hz, 2H), 7.04 (d, J ꢀ=ꢀ 8.4 Hz, 1H), 7.11 (dt,
Yield: 76 % (0.25 g). M.p. 175–177 °C. – IR (KBr): ν ꢀ=ꢀ 1727, J ꢀ=ꢀ 7.8, 1.2 Hz, 1H), 7.55 (dt, J ꢀ=ꢀ 7.8, 1.2 Hz, 1H), 8.20 (dd,
-1
+
1655 (Cꢀ=ꢀO) cm . – 1H NMR (400.0 MHz, CDCl3, 25 °C, TMS): J ꢀ=ꢀ 7.8, 1.6 Hz, 1H), 11.20 (s, NH). – MS: m/z ꢀ=ꢀ 353 [M] . –
δ ppm ꢀ=ꢀ 1.26 (t, J ꢀ=ꢀ 7.2 Hz, 3H), 2.46 (s, 3H), 4.02 (s, 2H), C14H15N3O4S2: anal. calcd. C 47.58, H 4.28, N 11.89; found C
4.20 (q, J ꢀ=ꢀ 7.2 Hz, 2H), 7.44–7.46 (m, 2H), 7.98 (brs, 1H), 47.25, H 4.19, N 11.97.
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A. Almasirad et al.: New 2-amido-1,3,4-thiadiazole derivatives as cytotoxic agentsꢂ
4.1.6 Ethyl 2-((5-(4-methoxybenzamido)-
1,3,4-thiadiazol-2-yl)thio)acetate (5f)
4.1.10 Ethyl 2-((5-(2,4-dichlorobenzamido)-
1,3,4-thiadiazol-2-yl)thio)acetate (5j)
Yield: 68 % (0.24 g). M.p. 144–146 °C. – IR (KBr): ν ꢀ=ꢀ 1729, Yield: 76 % (0.30 g). M.p. 164–166 °C. – IR (KBr): ν ꢀ=ꢀ 1727,
1664 (Cꢀ=ꢀO) cm . – 1H NMR (400 MHz, CDCl3, 25 °C, TMS): 1662 (Cꢀ=ꢀO) cm . – 1H NMR (400 MHz, CDCl3, 25 °C, TMS):
δ ppm ꢀ=ꢀ 1.25 (t, J ꢀ=ꢀ 6.8 Hz, 3H), 3.92 (s, 3H), 4.08 (s, 2H), δ ppm ꢀ=ꢀ 1.31 (t, J ꢀ=ꢀ 7.2 Hz, 3H), 3.98 (s, 2H), 4.25 (q, J ꢀ=ꢀ 7.2
4.20 (q, J ꢀ=ꢀ 6.8 Hz, 2H), 7.04 (d, J ꢀ=ꢀ 8.2 Hz, 2H), 8.23 (d, Hz, 2H), 7.65 (d, J ꢀ=ꢀ 8.4 Hz, 1H), 7.56 (brs, 1H), 7.75 (d, J ꢀ=ꢀ 8.4
J ꢀ=ꢀ 8.2 Hz, 2H), 12.61 (s, NH). – 13C NMR (100 MHz, CDCl3, Hz, 1H), 12.89 (s, NH). – 13C NMR (100.0 MHz, CDCl3, 25 °C,
25 °C, TMS): δ ppm ꢀ=ꢀ 14.0 (CH3), 33.5 (SCH2), 55.5 (OCH3), TMS): δ ppm ꢀ=ꢀ 14.1 (CH3), 34.9 (SCH2), 62.2 (OCH2), 127.6
62.1 (OCH2), 114.1 (2CAr), 123.0 (CAr), 130.8 (2CAr), 158.3 (CHAr), 130.63 (CHAr), 130.66 (CH2Ar), 130.7 (CHAr), 131.4
(COCH3), 162.0 (CAr), 163.8 (CAr), 164.8 (Cꢀ=ꢀO), 168.0 (Cꢀ=ꢀO). (CH2Ar), 133.2 (CH2Ar), 138.3 (CH2Ar), 158.9 (CAr), 160.37
-1
-1
+
+
– MS: m/z ꢀ=ꢀ 353 [M] . – C14H15N3O4S2: anal. calcd. C 47.58, H (CAr), 163.75 (Cꢀ=ꢀO), 167.82 (Cꢀ=ꢀO). – MS: m/z ꢀ=ꢀ 391 [M] . –
4.28, N 11.89; found C 47.81, H 4.46, N 11.60.
C13H11Cl2N3O3S2: anal. calcd. C 39.80, H 2.83, N 10.71; found
C 39.51, H 2.92, N 11.03.
4.1.7 Ethyl 2-((5-(2-chlorobenzamido)-1,3,4-thiadiazol-
2-yl)thio)acetate (5g)
4.1.11 Ethyl 2-((5-(3-fluorobenzamido)-1,3,4-thiadiazol-
2-yl)thio)acetate (5k)
Yield: 81 % (0.29 g). M.p. 157–159 °C. – IR (KBr): ν ꢀ=ꢀ 1729,
-1
1660 (Cꢀ=ꢀO) cm . – 1H NMR (400 MHz, CDCl3, 25 °C, TMS): Yield: 87 % (0.33 g). M.p. 189–191 °C. – IR (KBr): ν ꢀ=ꢀ 1730,
δ ppm 1.31 (t, J ꢀ=ꢀ 7.2 Hz, 3H), 3.94 (s, 2H), 4.24 (q, J ꢀ=ꢀ 7.2 1668 (Cꢀ=ꢀO) cm . – 1H NMR (400 MHz, CDCl3, 25 °C, TMS):
-1
Hz, 2H), 7.41–7.47 (m, 1H), 7.51–7.53 (m, 2H), 7.77 (d, J ꢀ=ꢀ 7.6 δ ppm ꢀ=ꢀ 1.25 (t, J ꢀ=ꢀ 7.2 Hz, 3H), 4.09 (s, 2H), 4.19 (q, J ꢀ=ꢀ 7.2
Hz, 1H), 12.95 (s, NH). – 13C NMR (100.0 MHz, CDCl3, 25 °C, Hz, 2H), 7.35 (t, J ꢀ=ꢀ 8.0 Hz, 1H), 7.55 (q, J ꢀ=ꢀ 7.6 Hz, 1H), 7.98
TMS): δ 14.1 (CH3), 35.1 (SCH2), 62.2 (OCH2), 127.1 (CH2Ar), (d, J ꢀ=ꢀ 9.2 Hz, 1H), 8.06 (d, J ꢀ=ꢀ 7.6 Hz, 1H), 13.07 (s, NH). – 13C
130.4 (CH2Ar), 130.6 (CH2Ar), 132.2 (CHAr), 132.4 (CHAr), NMR (100.0 MHz, CDCl3, 25 °C, TMS): δ ppm ꢀ=ꢀ 14.1 (CH3),
132.5 (CH2Ar), 158.6 (CAr), 160.5 (CAr), 164.7 (Cꢀ=ꢀO), 167.8 33.1 (SCH2), 62.1 (OCH2), 115.9 (d, CH2CAr, J ꢀ=ꢀ 92.8 Hz), 120.4
+
(Cꢀ=ꢀO). – MS: m/z ꢀ=ꢀ 357 [M] . – C13H12ClN3O3S2: anal. calcd. (d, CH2Ar, J ꢀ=ꢀ 84.4 Hz), 124.6 (d, CH2Ar, J ꢀ=ꢀ 11.6 Hz), 130.5
C 43.63, H 3.38, N 11.74; found C 43.50, H 3.59, N 11.51.
(d, CH2Ar, J ꢀ=ꢀ 31.2 Hz), 133.1 (d, CH2Ar, J ꢀ=ꢀ 29.2 Hz), 159.0
(CAr), 161.7 (CAr), 163.95 (Cꢀ=ꢀO), 164.42 (C-FAr, J ꢀ=ꢀ 10 Hz),
+
167.95 (Cꢀ=ꢀO). – MS: m/z ꢀ=ꢀ 341 [M] . – C13H12FN3O3S2: anal.
4.1.8 Ethyl 2-((5-(3-chlorobenzamido)-1,3,4-thiadiazol-
2-yl)thio)acetate (5h)
calcd. C 45.74, H 3.54, N 12.31; found C 45.38, H 3.25, N 12.13.
Yield: 73 % (0.26 g). M.p. 168–170 °C. – IR (KBr): ν ꢀ=ꢀ 1728, 4.1.12 Ethyl 2-((5-(3-nitrobenzamido)-1,3,4-thiadiazol-
-1
1661 (Cꢀ=ꢀO) cm . – 1H NMR (400 MHz, CDCl3, 25 °C, TMS): δ
2-yl)thio)acetate (5l)
ppm ꢀ=ꢀ 1.26 (t, J ꢀ=ꢀ 7.2 Hz, 3H), 4.12 (s, 2H), 4.22 (q, J ꢀ=ꢀ 7.2 Hz,
2H), 7.25–7.28 (m, 1H), 7.29 (s, 1H), 7.73 (dd, J ꢀ=ꢀ 6.8, 1.2 Hz, Yield: 89 % (0.33 g). M.p. 180–182 °C. – IR (KBr): ν ꢀ=ꢀ 1730,
1H), 8.48 (dd, J ꢀ=ꢀ 6.8, 1.2 Hz, 1H), 12.67 (s, 1H). – MS: m/z ꢀ=ꢀ 1669 (Cꢀ=ꢀO) cm . – 1H NMR (400 MHz, CDCl3, 25 °C, TMS):
-1
+
357 [M] . – C13H12ClN3O3S2: anal. calcd. C 43.63, H 3.38, N δ ppm ꢀ=ꢀ 1.25 (t, J ꢀ=ꢀ 7.2 Hz, 3H), 4.12 (s, 2H), 4.20 (q, J ꢀ=ꢀ
11.74; found C 43.39, H 3.16, N 11.91.
7.2 Hz, 2H), 7.28 (t, J ꢀ=ꢀ 4.6 Hz, 1H), 7.73 (d, J ꢀ=ꢀ 4.6 Hz, 1H),
8.49 (d, J ꢀ=ꢀ 4.6 Hz, 1H), 12.69 (s, NH). – MS: m/z ꢀ=ꢀ 368 [M] .
+
– C13H12N4O5S2: anal. calcd. C 42.38, H 3.28, N 15.21; found
C 42.61, H 3.09, N 15.54.
4.1.9 Ethyl 2-((5-(4-chlorobenzamido)-1,3,4-thiadiazol-
2-yl)thio)acetate (5i)
Yield: 80 % (0.28 g). M.p. 181–183 °C. – IR (KBr): ν ꢀ=ꢀ 1729, 4.1.13 Ethyl 2-((5-(thiophene-2-carboxamido)-
-1
1660 (Cꢀ=ꢀO) cm . – 1H NMR (400 MHz, CDCl3, 25 °C, TMS):
1,3,4-thiadiazol-2-yl)thio)acetate (5m)
δ ppm ꢀ=ꢀ 1.29 (t, J ꢀ=ꢀ 7.2 Hz, 3H), 4.09 (s, 2H), 4.25 (q, J ꢀ=ꢀ 7.2
Hz, 2H), 7.56 (d, J ꢀ=ꢀ 8.4 Hz, 2H), 8.07 (d, J ꢀ=ꢀ 8.4 Hz, 2H), Yield: 82 % (0.27 g). M.p. 175–177 °C. – IR (KBr): ν ꢀ=ꢀ 1728,
11.24 (s, NH). – MS: m/z ꢀ=ꢀ 357 [M] . – C13H12ClN3O3S2: anal. 1663 (Cꢀ=ꢀO) cm . – 1H NMR (400 MHz, CDCl3, 25 °C, TMS):
+
-1
calcd. C 43.63, H 3.38, N 11.74; found C 43.31, H 3.19, N 12.08. δ 1.25 (t, J ꢀ=ꢀ 7.2 Hz, 3H), 4.12 (s, 2H), 4.20 (q, J ꢀ=ꢀ 7.2 Hz,
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ꢀꢀꢀꢁ
6ꢀ ꢀA. Almasirad et al.: New 2-amido-1,3,4-thiadiazole derivatives as cytotoxic agents
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+
(d, J ꢀ=ꢀ 4.6 Hz, 1H), 12.69 (s, NH). – MS: m/z ꢀ=ꢀ 329 [M] .
– C11H11N3O3S3: anal. calcd. C 40.11, H 3.37, N 12.76; found C
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4.1.14 Ethyl 2-((5-(furan-2-carboxamido)-
1,3,4-thiadiazol-2-yl)thio)acetate (5n)
Yield: 79 % (0.25 g). M.p. 171–173 °C. – IR (KBr): ν ꢀ=ꢀ 1729,
-1
1660 (Cꢀ=ꢀO) cm . – 1H NMR (400 MHz, CDCl3, 25 °C, TMS):
δ ppm ꢀ=ꢀ 1.28 (t, J ꢀ=ꢀ 7.2 Hz, 3H), 4.08 (s, SCH2), 4.24 (q, J ꢀ=ꢀ
7.2 Hz, 2H), 6.66 (dd, J ꢀ=ꢀ 3.6, 1.6 Hz, 1H), 7.58 (dd, J ꢀ=ꢀ 3.6,
1.6 Hz, 1H), 7.69 (dd, J ꢀ=ꢀ 3.6, 1.6 Hz, 1H), 11.28 (s, 1H, NH).
+
– MS: m/z ꢀ=ꢀ 313 [M] . – C11H11N3O4S2: anal. calcd. C 42.16,
H 3.54, N 13.41; found C 42.51, H 3.75, N 13.59.
5 Supporting Information
Experimental details of the biological studies and pictures
1
of the H NMR and 13C NMR spectra of 5a–n are available
online (DOI: 10.1515/znb-2015-0138).
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Acknowledgments: This work was supported by a grant
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Z. Naturforsch.ꢂ
ꢂ2016 | Volume x | Issue x(b)
Graphical synopsis
Ali Almasirad, Loghman Firoozpour,
Maliheh Nejati, Najmeh Edraki,
Omidreza Firuzi, Mehdi Khoshne-
viszadeh, Mohammad Mahdavi,
Setareh Moghimi, Maliheh Safavi,
Abbas Shafiee and Alireza Foroumadi
Design, synthesis, and biological
evaluation of new series of
2-amido-1,3,4-thiadiazole derivatives
as cytotoxic agents
DOI 10.1515/znb-2015-0138
Z. Naturforsch. 2016; x(x)b: xxx–xxx
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