In-Vitro anti-HIV and antitumor activity of new 3,6-disubstituted [1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles and thiadiazine analogues

Article abstract of DOI:10.1002/ardp.200700272

A series of [1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles (7-15) and the thiadiazine analogues 16-18 have been synthesized under microwave irradiation (MWI). All synthesized compounds are evaluated for their antiviral activity against the replication of HIV-1 and HIV-2 activity in MT-4. However, compounds 12 and 18 showed EC₅₀ = 2.11 and 1.97 μg/mL. The results suggest that these compounds can be considered as a new lead in the development of antiviral agents. Compounds 4-18 were tested in vitro against a panel of tumor cell lines. All compounds are inactive against all the tumor sub-lines, except 10 which exhibited activity against CD4⁺ human acute T-lymphoblastic leukaemia of CC₅₀ = 64 μM.

Full text of DOI:10.1002/ardp.200700272

Arch. Pharm. Chem. Life Sci. 2008, 341, 365–369
Y. A. Al-Soud et al.
365
Full Paper
In-Vitro Anti-HIV and Antitumor Activity of New 3,6-
Disubstituted [1,2,4]Triazolo[3,4-b][1,3,4]thiadiazoles and
Thiadiazine Analogues
Yaseen A. Al-Soud1, Najim A. Al-Masoudi2, Robert Loddo3, and Paola La Colla3
1 Department of Chemistry, College of Science, University of Al al-Bayt, Al-Mafraq, Jordan
2 Fachbereich Chemie, Universitꢀt Konstanz, Konstanz, Germany (formerly)
3 Department of Biomedical Sciences and Technologies, University of Cagliari, Monserrato, Italy
A series of [1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles (7–15) and the thiadiazine analogues 16–18
have been synthesized under microwave irradiation (MWI). All synthesized compounds are eval-
uated for their antiviral activity against the replication of HIV-1 and HIV-2 activity in MT-4. How-
ever, compounds 12 and 18 showed EC50 = 2.11 and 1.97 lg/mL. The results suggest that these
compounds can be considered as a new lead in the development of antiviral agents. Compounds
4–18 were tested in vitro against a panel of tumor cell lines. All compounds are inactive against
all the tumor sub-lines, except 10 which exhibited activity against CD4+ human acute T-lympho-
blastic leukaemia of CC50 = 64 lM.
Keywords: Anti-HIV activity / Antitumor activity / Microwave-assisted synthesis / Triazolothiadiazoles / Thiadiazines /
Received: December 22, 2007; accepted: February 18, 2008
DOI 10.1002/ardp.200700272
In view of these findings and in continuation of our
previous work [21] on the synthesis of acyclic C-nucleo-
sides of triazolothiadiazoles and thiadiazines, herein, we
report the synthesis of some [1,2,4]triazolo[3,4-b][1,3,4]-
thiadiazoles, and the evaluation of triazolothiadiazine
analogues, which could be favorable candidates for
achieving some pharmacological specificity regarding
the development of effective clinical anticancer and anti-
HIV drugs.
Introduction
A number of [1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles and
[1,2,4]triazolo[1,3,4]thiadiazines possess diverse pharma-
cological activities [1–7] such as antimicrobial [8], antitu-
mor [9, 10], antiviral [3, 11], antibacterial [3, 12], herbici-
dal [13], anti-HIV-1 [14], CNS stimulant [15], antifungal
[16, 17], and antihelminitic [18] activities. Holla et. al. [9]
reported that the various biological activities of
[1,3,4]thiadiazoles are possibly due to the presence of the
=N-C-S moiety. Recently, Shaker [19] has reviewed the syn-
thesis of biological activity of various triazoles, triazolo-
thiadiazoles and triazolothiadiazines. Additionally, Al-
Masoudi et al. [20] have reviewed recently the synthetic
approaches of 1,2,4-triazoles and their pharmacological
importance.
Chemistry
Condensation of the appropriate substituted benzoic
acids (3-bromo-, 4-amino, and 3,4-dichlorobenzoic acids)
1–3 with thiocarbohydrazide in pyridine under micro-
wave irradiation (MWI) for 15 min afforded, after purifi-
cation, the 4-amino-5-aryl-2,4-dihydro-[1,2,4]triazole-3-
thions 4–6 in 75, 73, and 91% yield, respectively.
Treatment of 4–6 with the appropriate substituted
benzoic acids in DMF at 1408C for 145 min gave the 3,6-
disubstituted 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole deriv-
atives 7–15 in 26–97% yield. The structures of 4–6 and
7–15 were confirmed by the 1H-, 13C-NMR, and mass spec-
tra. Compound 4–6 and 7–15 showed a similar NMR
Correspondence: Najim A. Al-Masoudi, present address: P. O. Box
100552, D-78405 Konstanz, Germany.
E-mail: Najim.Al-Masoudi@gmx.de
Fax: +49 7531 34435
Abbreviation: microwave irradiation (MWI)
i 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

366
Y. A. Al-Soud et al.
Arch. Pharm. Chem. Life Sci. 2008, 341, 365–369
Conditions and reagents: (i) (NH2NH)2C=S, pyridine, MWI, 15 min; (ii) RCO2H; DMF, MWI, 145 min, 1408C.
Scheme 1. Synthesis route of compounds 1–15.
spectral pattern. In the 13C-NMR spectra of 4–6, the reso-
nances at the region d 165.2–166.2 and d 148.0–148.2
were assigned to the carbons of C-SH and C=N groups,
respectively. The protons of 7–15 were fully analyzed,
while the 13C-NMR spectra showed two high-field signals
at the regions d 165.2–167.8 ppm and d 162.1–164.8
ppm which are attributed to N=C-S and C-6, respectively.
C-3 (C=N) displayed signals at d 143.1–147.8 ppm. The
carbons of coumarin, pyridine, pyrazine, pyrrole, thio-
phene, and furan were assigned. The synthesis route of
compounds 1–15 is depicted in Scheme 1.
Next, our attention focused on synthesis of new tria-
zolo-thiadiazine as potentially active compounds. Thus,
treatment of 6 with 2-chloracetonitrile in the presence of
Reagent and conditions: (i) 2-chloroacetonitril, 3% H2SO4/SiO2, MWI, 30 min; (ii), 2-
chloroacetic acid, NaOAc, EtOH, MWI, 30 min; (iii) PhCOCH2Cl, EtOH, MWI, 30 min.
3% H2SO4/SiO2 under MWI at 858C for 30 min afforded 16
(65%). Similar treatment of 6 with 2-chloroacetic acid
containing NaOAc furnished 17 (68%). Further, heating
of 6 with phenacyl chloride under MWI gave 18 (61%)
(Scheme 2). Structures of the newly synthesized com-
Scheme 2. Synthesis route of compounds 16–18.
pounds 16–18 were assigned by the1H, 13C-NMR and mass well as their activity against other viruses, such as
spectra. The H-NMR spectra showed rather similar pat- human T-cells containing an integrated HTLV-1 genome,
1
terns for the phenyl, while the singlets at d 3.97–
MDBK (Madin-Darby bovine (normal) kidney cells) with
4.39 ppm were attributed to SCH2 group. In the 13C-NMR BVDV (bovine viral diarrhea virus), BHK (hamster normal
spectra of 16–18, C=N (C-3) resonated at d 147.7, 148.8, kidney fibroblast), BHK (kidney fibroblast) cells from the
and 147.5 ppm, respectively, while C-6 (C=O at compound YFV (yellow fever virus) and Reo (reovirus 1), mock-
17) appeared at higher field d 164.2, 171.5, 164.0 ppm, infected VERO-76 (monkey normal kidney), HSV-1 (her-
respectively. CH2S carbons resonated at d 37.8, 34.2, and pesvirus 1), VV (vaccinia virus), VSV (vesicular stomatitis
36.0 ppm, respectively.
virus), CVB-2 (coxsackievirus B2), Sb-1(poliovirus 1) and
RSV (respiratory syncytial virus). The anti-HIV activity is
summarized in Table 1, in which the data for efavirenz
[23] and capravirine [24] are included for comparison. All
Biology
In-vitro anti-HIV and other virus assays
Compounds 4–18 were tested for their in-vitro anti-HIV-1 the compounds are inactive except for 12 and 18 which
(strain IIIB) and HIV-2 (strain ROD) activity in human T- showed EC50 = 2.11 and 1.97 lg/mL, respectively for which
lymphocyte (MT-4) cells using the MT-4/MTT assay [22], as the data can be discussed. However, none of our com-
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Arch. Pharm. Chem. Life Sci. 2008, 341, 365–369
New Disubstituted Triazolo-thiadiazoles and Thiadiazines
367
Table 1. In-vitro anti-HIV-1a) and HIV-2b) of some new triazolo-
thiadiazoles and thiadiazines.
In-vitro antitumor assay
Compounds 4–18 were tested in vitro against a panel of
tumor cell lines, consisting of CD4+ human T-cells with
integrated leukaemia (CCRF-CEM), human acute T-lym-
phoblastic leukaemia (WIL-2NS), human splenic B-lym-
phoblastoid cells (CCRF-SB), human acute B-lymphoblas-
tic leukaemia (SK-MEL-28), human skin melanoma (SK-
MEL-28), human breast adenocarcinoma (MCF-7), human
lung squamous carcinoma (SK-MES-1), human hepatocel-
lular carcinoma (HepG2), human prostate carcinoma
(DU-145), human foreskin fibroblast (CRL7065), and
human lung fibroblast (MRC-5), using the microculture
tetrazolium assay (MTT) method for estimation of the in-
vitro tumor-inhibiting activity. All compounds are inac-
tive against all the tumor sub-lines, except 10 which
exhibited activity against CD4+ human acute T-lympho-
blastic leukaemia of CC50 = 64 lM.
Compound Virus
strain
av. EC50
(lg/mL)
av. CC50
(lg/mL) l SD
SI
4
IIIB
A75.4
A75.4
75.4 l 6.71
75.4 l 6.71
12.00 l 1.13
12.00 l 1.13
72.83 l 3.36
72.83 l 3.36
4.12 l 2.08
4.12 l 2.08
108.3 l 8.86
108.3 l 8.86
67.8 l 13.86
67.8 l 13.86
19.61 l 20.84
19.61 l 20.84
80.05 l 11.17
80.05 l 11.17
2.11 l 1.13
2.11 l 1.13
68.48 l 5.63
68.48 l 5.63
92.70 l 15.2
92.70 l 15.2
27.20 l 7.79
27.20 l 7.71
2.70 l 5.30
2.70 l 5.30
35.23 l 6.20
35.23 l 6.20
1.97 l 0.40
1.97 l 0.40
40
a1
a1
a1
a1
a1
a1
a1
a1
a1
a1
a1
a1
a1
a1
4
a1
a1
a1
a1
a1
a1
a1
a1
a1
a1
a1
a1
a1
a1
a1
13333
7857
ROD
IIIB
5
A12.00
A12.00
A72.83
A72.83
A4.12
ROD
IIIB
6
ROD
IIIB
7
IIIB
A4.12
8
IIIB
A108.3
A108.3
A67.8
ROD
IIIB
9
ROD
IIIB
A67.8
10
A19.61
A19.61
A80.05
A80.05
A2.11
ROD
IIIB
11
ROD
IIIB
12
ROD
IIIB
A2.11
13
A68.48
A68.48
A92.70
A92.70
A27.51
A27.20
A2.70
Experimental
ROD
IIIB
14
Melting points are uncorrected and were measured on a Bꢀchi
melting point apparatus B-545 (Bꢀchi Labortechnik AG, Switzer-
land). Microanalytical data were obtained with a Vario Elemen-
tar apparatus (Shimadzu, Japan). NMR spectra were recorded on
300 and 600 MHz (1H) and at 62.9 MHz (13C) spectrometers
(Bruker, Germany) with TMS as internal standard and on d scale
ROD
IIIB
15
ROD
IIIB
16
ROD
IIIB
A2.70
17
A35.23
A35.23
A1.97
1
in ppm. Heteronuclear assignments were verified by H- / 13C-
ROD
IIIB
18
HMBC experiment. Mass spectra were recorded at 70 eV on EI
and FAB mass spectra were measured on a MAT 8200 spectrome-
ter (Finnigan MAT, USA) using 3-nitrobenzyl alcohol (NBOH) or
glycerol as matrices. Some molecular ions were detected by dop-
ing the sample with Na+ ion.
ROD
IIIB
A1.97
A0.003
A0.0014
Efavirenz
Capravirine IIIB
11
a)
Anti-HIV-1 activity measured with strain IIIB.
Anti-HIV-2 activity measured with strain ROD.
b)
General preparation of 4-amino-5-aryl-1,2,4-triazole-
3-thiols 4–6
A mixture of 1–3 (1.00 mmol) and thiocarbohydrazide (106 mg,
1.00 mmol) in pyridine (5 mL) was heated at 1408C under MWI
for 15 min. After cooling, the solution was evaporated to dryness
and the residue was washed with water, acidified with conc.
HCl, filtered, washed with water, and dried. The solid was recrys-
tallized from EtOH to give the desired products 4–6.
pounds approached the activity level of the reference
compounds.
Compounds 12 and 18 are equipotent against HIV-1
and HIV-2 replication in vitro and, therefore, most prob-
ably they are no NNRTI's (Non-Nucleoside Reverse Tran-
scriptase Inhibitors). The anti-HIV activity and the selec-
tivity of these compounds are however too limited to per-
form extensive mode-of-action studies. The synthesis of
new analogues of this triazolothiadiazines derivative
may lead to the discovery of more potent and selective
analogues that will allow the elucidation of their molecu-
lar mode-of-action.
4-Amino-5-(3-bromophenyl)-1,2,4-triazole-3-thiols 4 [25]
From 3-bromo-benzoic acid (201 mg). Yield: 203 mg (75%), mp.
155–1578C. 1H-NMR (DMSO-d6): d 8.05 (s, 1H, SH), 7.94 (d, 2H, J =
7.7 Hz, ArH), 7.84 (d, 1H, J = 7.9 Hz, ArH), 7.50 (t, 1H, J = 7.8 Hz,
ArH), 3.61 (br s, 2H, NH2). 13C-NMR (DMSO-d6): d 165.9 (C-SH),
148.0 (C=N), 135.5, 132.9, 131.7, 130.8, 128.2 (Ar), 121.6 (Ar-C-Br).
Anal. calc. for C8H7BrN4S (271.14): C, 35.44; H, 2.60; N, 20.66.
Found: C, 35.19; H, 2.52; N, 20.44. MS: m/z (FAB) 271/273 [M + H]+.
Regarding other viruses, the Coxsackie virus B (CVB-2)
was the only virus inhibited by compounds 9, 10, 11, and
14 with EC50 = 12, 20, 31, and 22 lg/mL, respectively (CC50
A 100 lg/mL), meanwhile, all other compounds demon-
strated inactivity against the other screened viruses.
4-Amino-5-(4-aminophenyl)-1,2,4-triazole-3-thiols 5 [25]
From 4-amino-benzoic acid (137 mg). Yield: 198 mg (73%), mp.
162–1638C. 1H-NMR (DMSO-d6): d 8.25 (s, 1H, SH), 7.90 (d, 2H, J =
7.7 Hz, ArH), 6.80 (d, 2H, J = 7.8 Hz, ArH), 5.80 (br s, 2H, NH2), 4.31
(br s, 2H, NH2). 13C-NMR (DMSO-d6): d 166.5 (C-SH), 147.5 (C=N),
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368
Y. A. Al-Soud et al.
Arch. Pharm. Chem. Life Sci. 2008, 341, 365–369
147.2 (Ar-C-NH2), 130.1, 128.5, 119.6 (ArC), Anal. calc. for C8H9N5S
(207.26): C, 46.36; H, 4.38; N, 33.79. Found: C, 46.19; H, 4.29; N,
33.58. MS: m/z (FAB) 208 [M + H]+.
6-(4-Aminophenyl)-3-(3,4-dichlorophenyl)-
[1,2,4]]triazolo[3,4-b][1,3,4]thiadiazole 10
From 6 (65 mg) and 4-amino-benzoic acid (34 mg).Yield: 77 mg
1
(85%), mp. 198–2008C. H-NMR (DMSO-d6): d 8.05 (dd, 1H, J =
7.8 Hz, J = 2.1 Hz, ArH), 7.89 (d, 1H, J = 2.1 Hz, ArH), 7.78 (s, 1H,
ArH), 7.61 (d, 2H, J = 7.0 Hz, ArH), 6.53 (d, 2H, J = 7.0 Hz, AH), 3.99
(br s, 2H, NH2). 13C-NMR (DMSO-d6): d 166.1 (N=C-S), 162.4 (C-6),
148.0 (ArC-NH2), 145.0 (C=N), 131.4, 131.3 (AC-Cl), 130.9, 130.8,
129.2, 128.2, 122.8, 120.1 (ArC). Anal. calc. for C15H9Cl2N5S
(362.24): C, 49.74; H, 2.50; N, 19.33. Found: C, 49.52; H, 2.40; N,
19.02. MS: m/z (FAB) 362/364 [M + H]+.
4-Amino-5-(3,4-dichlorophenyl)-1,2,4-triazole-3-thiols 6
From 4-amino-benzoic acid (191 mg). Yield: 238 mg (91%), mp.
197–1988C. 1H-NMR (DMSO-d6): d 8.07(dd, 1H, J = 7.8 Hz, 1.9 Hz,
ArH), 7.90 (d, 1H, J = 2.0 Hz, ArH), 7.78 (d, 1H, J = 1.9 Hz ArH), 5.85
(br s, 2H, NH2). 13C-NMR (DMSO-d6): d 165.4 (C-SH), 148.0 (C=N),
131.4, 131.3 (A-C-Cl), 131.0, 130.9, 127.0, 129.2 (Ar). Anal. calc. for
C8H6Cl2N4S (261.13): C, 36.80; H, 2.32; N, 21.46. Found: C, 36.61;
H, 2.26; N, 21.19. MS: m/z (FAB) 261/263 [M + H]+.
3-(3,4-Dichlorophenyl)-6-(pyridin-3-yl)-
[1,2,4]]triazolo[3,4-b][1,3,4]thiadiazole 11
From 6 (65 mg), picolinic acid (31 mg) and POCl3 (15 mL) at 958C.
1
General procedure of 3,6-diaryl-6-[1,2,4]]triazolo[3,4-
Yield: 23 mg (26%), mp. 80–828C. H-NMR (CDCl3): d 9.19–8.21
(m, 4H, pyridine-H), 8.05 (dd, 1H, J = 7.7 Hz, J = 1.9 Hz, ArH), 7.83
(d, 1H, J = 1.9 Hz, ArH), 7.72 (s, 1H, ArH). 13C-NMR (DMSO-d6): d
165.9 (N=C-S), 163.0 (C-6), 148.9 (pyridine-C), 145.9 (C=N), 136.2
(pyridine-C), 131.7, 131.5 (ArC-Cl), 131.4, 131.7, 129.5 (ArC),
127.2, 123.7 (pyridine-C). Anal. calc. for C14H7Cl2N5S (348.21): C,
48.29; H, 2.03; N, 20.11. Found: C, 48.02; H, 1.96; N, 19.93. MS: m/
z (FAB) 348/350 [M + H]+.
b][1,3,4]thiadiazoles 7–15
A mixture of 4–6 (0.25 mmol) and aryl or alkyl benzoic acid
(0.25 mmol) in DMF (5 mL) was heated at 1408C in the microwave
for 145 min. After cooling, the solution was evaporated to dry-
ness to give solid or semi-solid products. The solid product was
recrystallized from EtOH to give the desired products.
3-(3,4-Dichlorophenyl)-6-(pyrazin-2-yl)-
[1,2,4]]triazolo[3,4-b][1,3,4]thiadiazole 12
3-(3-Bromophenyl)-6-(3,4-dichlorophenyl)-
[1,2,4]]triazolo[3,4-b][1,3,4]thiadiazole 7
From 6 (65 mg) and pyrazine-2-carboxylic acid (31 mg). Yield:
24.4 mg (28%), mp. 122–1268C. 1H-NMR (DMSO-d6): d 8.51–8.32
(m, 3H, pyrazine-H), 8.05 (dd, 1H, J = 7.8 Hz, J = 1.8 Hz, ArH), 7.88
(d, 1H, J = 1.8 Hz, ArH), 7.75 (s, 1H, ArH). 13C-NMR (DMSO-d6): d
167.8 (N=C-S), 165.3 (C-6), 147.2, 146.2, 145.9, 145.0 (pyrazine-C),
144.1 (C=N), 133.4, 133.0 (ArC-Cl), 131.1, 130.9, 129.4 (ArC). Anal.
calc. for C13H6Cl2N6S (349.20): C, 44.71; H, 1.73; N, 24.07. Found:
C, 44.50; H, 1.66; N, 23.85. MS: m/z (FAB) 349/351 [M + H]+.
From 4 (68 mg) and 3,4-dichloro-benzoic acid (48 mg). Yield:
88 mg (83%), mp. 142-1448C. 1H-NMR (DMSO-d6): d 8.06 (dd, 1H, J
= 7.8 Hz, J = 2.0 Hz, ArH), 7.95–7.76 (m, 5H, ArH), 7.48 (t, 1H, J =
7.8 Hz, ArH). 13C-NMR (DMSO-d6): d 165.8 (N=C-S), 163.3 (C-6),
143.1 (C=N), 135.5, 135.4 (AC-Cl), 133.2, 132.9, 131.6, 131.4,
130.9, 130.7, 129.2, 128.1, 126.8 (Ar), 121.6 (ArC-Br). Anal. calc.
for C15H7BrCl2N4S (426.12): C, 42.28; H, 1.66; N, 13.15. Found: C,
42.48; H, 1.56; N, 13.37. MS: m/z (FAB) 426 [M + H]+.
3-(3,4-Dichlorophenyl)-6-(pyrrol-2-yl)-[1,2,4]]triazolo[3,4-
b][1,3,4]thiadiazole 13
3-(4-Aminophenyl)-6-(coumarin-3-yl)-[1,2,4]]triazolo[3,4-
From 6 (65 mg) and pyrrole-2-carboxylic acid (28 mg). Yield:
30 mg (36%), semi-solid. 1H-NMR (DMSO-d6): d 11.0 (br s, 1H, NH),
8.17 (dd, 1H, J = 7.8 Hz, J = 2.2 Hz, ArH), 7.95 (d, 1H, J = 2.2 Hz,
ArH), 7.61 (s, 1H, ArH), 6.85-6.68 (m, 3H, pyrrole-H). 13C-NMR
(DMSO-d6): d 166.5 (N=C-S), 163.0 (C-6), 145.5 (C=N), 131.8, 131.7
(AC-Cl), 131.0, 130.9, 130.0, 129.4 (ArC), 119.5, 118.5, 111.0, 110.0
(pyrrole-C). MS: m/z (FAB) 359/361 [M + Na]+.
b][1,3,4]thiadiazole 8
From 5 (52 mg) and coumarin-3-carboxylic acid (48 mg). Yield:
42 mg (47%), mp. 100–1038C.1H-NMR (DMSO-d6): d 7.60 (d, 2H, J =
7.0 Hz, ArH), 7.39 (s, 1H, coumarin-H), 7.32–6.77 (m, 4H, cou-
marin-H), 6.53 (d, 2H, J = 7.0 Hz, ArH), 4.68 (br s, 2H, NH2). 13C-
NMR (DMSO-d6): d 165.5 (N=C-S), 163.5 (C-6), 158.8 (C=O), 150.7
(coumarin-C-8a), 148.5 (ArC-NH2), 146.0 (C=N), 131.2, 128.1,
128.0, 127.0, 124.6, 121.1, 118.9, 116.8, (ArC + coumarin-C). Anal.
calc. for C18H11N5O2S (361.38): C, 59.82; H, 3.07; N, 19.38. Found:
C, 59.68; H, 2.98; N, 19.03. MS: m/z (FAB) 362 [M + H]+.
3-(3,4-Dichlorophenyl)-6-(thiophen-2-yl)-
[1,2,4]]triazolo[3,4-b][1,3,4]thiadiazole 14
From 6 (65 mg) and thiophene-2-carboylic acid (32 mg). Yield:
1
48 mg (54%), semi-solid. H-NMR (DMSO-d6): d 8.09 (dd, 1H, J =
7.7 Hz J = 2.0 Hz, ArH), 7.84 (d, H, J = 2.0 Hz, ArH), 7.49 (s, 1H,
ArH), 7.00-7.25 (m, 3H, thiophen-H). 13C-NMR (DMSO-d6): d 165.2
(N=C-S), 163.1 (C-6), 147.8 (C=N), 133.0 (C2-thiophene), 132.9 (ArC-
Cl), 131.5, 130.5, 129.9, 128.6 (ArC), 127.9, 127.7, 125.0 (thio-
phene-C). MS: m/z (FAB) 353/355 [M + H]+.
3,6-Bis-(3,4-dichlorophenyl)-[1,2,4]]triazolo[3,4-b][1,3,4]-
thiadiazole 9
From 6 (65 mg) and 3,4-dichloro-benzoic acid (48 mg). Yield:
101 mg (97%), mp. 203–2058C.1H-NMR (DMSO-d6): d 8.04 (dd, 1H,
J = 7.5 Hz, J = 1.9 Hz, ArH), 7.88 (dd, 1H, J = 7.8 Hz, J = 2.0 Hz, ArH),
7.85 (d, 1H, J = 2.0 Hz, ArH), 7.77 (d, 1H, J = 1.9 Hz, ArH), 7.74 (s,
1H, ArH). 13C-NMR (DMSO-d6): d 165.4 (N=C-S), 164.8 (C-6), 144.7
(C=N), 135.6, 131.5 (ArC-Cl), 131.4, 130.9, 130.0, 129.3, 129.0 (Ar).
Anal. calc. for C15H6Cl4N4S (416.11): C, 43.30; H, 1.45; N, 13.46.
Found: C, 43.02; H, 1.38; N, 13.19. MS: m/z (FAB) 416/418 [M + H]+.
3-(3,4-Dichlorophenyl)-6-(furan-2-yl)-[1,2,4]]triazolo[3,4-
b][1,3,4]thiadiazole 15
From 6 (65 mg) and furan-2-carboxylic acid (28 mg). Yield: 40 mg
(48%), semi-solid. 1H-NMR (DMSO-d6): d 8.07 (dd, 1H, J = 7.8 Hz J =
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Arch. Pharm. Chem. Life Sci. 2008, 341, 365–369
New Disubstituted Triazolo-thiadiazoles and Thiadiazines
369
2.0 Hz, ArH), 7.82 (d, H, J = 2.0 Hz, ArH), 7.46 (s, 1H, ArH), 7.35 (dd,
1H, J = 7.9 Hz J = 2.5 Hz furan-H), 6.56–6.46 (m, 2H, furan-H). 13C-
NMR (DMSO-d6): d 165.2 (N=C-S), 162.1 (C-6), 147.6 (C=N), 143.0
(C2-furan), 133.1, 132.8 (ArC-Cl), 131.5, 130.5, 129.9, 128.6 (Ar),
112.0, 111.2 (furan-C). Anal. calc. for C13H6Cl2N4OS MS: m/z (FAB)
360/362 [M + Na]+.
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thiadiazin-6-amine 16
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1.00 mmol), and 3% H2SO4/SiO2 (20 mg). The mixture was heated
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to 5%) and CHCl3 to give 16 (187 mg, 65%), mp. 137–1418C. H-
NMR (DMSO-d6): d 8.02 (dd, 1H, J = 7.6 Hz J = 2.0 Hz, ArH), 7.80 (d,
H, J = 2.0 Hz, ArH), 7.44 (s, 1H, ArH), 6.31 (br s, 2H, NH2), 2.97 (s,
2H, SCH2). 13C-NMR (DMSO-d6): d 164.2 (C6-NH2), 147.7, 147.9
(C=N), 133.3, 133.0 (Ar-C-Cl), 130.6, 129.2, 128.1 (Ar), 37.8 (SCH2).
Anal. calc. for C10H7Cl2N5S (300.17): C, 40.01; H, 2.35; N, 23.33.
Found: C, 39.89; H, 2.26; N, 23.02. MS: m/z (FAB) 300/302 [M + H]+.
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thiadiazin-6-one 17
Jie, J. Heterocycl. Chem. 2000, 37, 269–271.
From 6 (250 mg, 0.96 mmol) and 2-chloroacetic acid (94 mg,
1.00 mmol) in EtOH (15 mL) containing NaOAc (30 mg). The mix-
ture was heated under MWI at 858C for 30 min. After cooling,
the residue was partitioned between CHCl3 (3620 mL) and
water (20 mL). The combined organic extracts were dried
(Na2SO4), filtered, and evaporated to dryness. The residue was
purified on a short column of silica gel (5 g) and eluted with an
gradient, with MeOH (0 to 5%) and CHCl3 to give 17 (205 mg,
68%), mp. 111–1148C. 1H-NMR (DMSO-d6): d 8.60 (s, 1H, NH), 7.92
(dd, 1H, J = 7.7 Hz J = 1.9 Hz, ArH), 7.77 (d, H, J = 1.9 Hz, ArH), 7.41
(s, 1H, ArH), 3.78 (s, 2H, SCH2). 13C-NMR (DMSO-d6): d 171.5 (C=O),
147.8 (C=N), 133.7, 133.2 (Ar-C-Cl), 130.4, 129.0, 128.2 (Ar), 34.2
(SCH2). Anal. calc. for C10H6Cl2N4OS (301.15): C, 39.88; H, 2.01; N,
18.60. Found: C, 39.62; H, 1.95; N, 18.41. MS: m/z (FAB) 301/303 [M
+ H]+.
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From 6 (350 mg, 1.34 mmol) and phenacyl chloride (216 mg,
1.40 mmol) in EtOH (15 mL). The mixture was heated at 958C
under MWI for 30 min. After cooling, the residue was parti-
tioned between CHCl3 (3620 mL) and water (20 mL). The com-
bined organic extracts was dried (Na2SO4), filtered, and evapo-
rated to dryness. The residue was purified on a short column of
silica gel (7 g) and eluted with an gradient, with MeOH (0 to 5%)
and CHCl3 to give 18 (295 mg, 61%), mp. 137-1418C. 1H-NMR
(DMSO-d6): d 7.96 (dd, 1H, J = 7.5 Hz J = 1.9 Hz, ArH), 7.91 (m, 2H,
ArH), 7.75 (d, H, J = 1.9 Hz, ArH), 7.53–7.47 (m, 3H, ArH), 7.43 (s,
1H, ArH), 4.39 (s, 2H, SCH2). 13C-NMR (DMSO-d6): d 164.0 (C-6),
147.5 (C=N), 133.8 (Ar), 133.5, 133.2 (Ar-C-Cl), 131.0, 130.6, 129.2,
128.9 (Ar), 36.0 (SCH2). Anal. calc. for C16H10Cl2N4S (361.25): C,
53.20; H, 2.79; N, 19.63. Found: C, 52.98; H, 2.70; N, 15.30. MS:
m/z (FAB) 361/363 [M + H]+.
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i 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com