Synthesis of 3-((2,4-dichlorophenoxy)methyl)-1,2,4-triazolo(thiadiazoles and thiadiazines) as anti-inflammatory and molluscicidal agents

Article abstract of DOI:10.1016/j.ejmech.2010.01.030

A series of fused and non fused 1,2,4-triazoles with (2,4-dichlorophenoxy) moiety are prepared utilizing 3-((2,4-dichlorophenoxy)methyl)-4-amino-4H-1,2,4-triazole-5-thiol (3). The latter on reaction with carboxylic acids, ethylchloroformate, ethylcyanoace

Full text of DOI:10.1016/j.ejmech.2010.01.030

European Journal of Medicinal Chemistry 45 (2010) 1906–1911
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis of 3-((2,4-dichlorophenoxy)methyl)-1,2,4-triazolo(thiadiazoles
and thiadiazines) as anti-inflammatory and molluscicidal agents
,
M.F. El Shehry a, A.A. Abu-Hashem b, E.M. El-Telbani a
*
a National Research Centre, Green Chemistry Department, 12622 Dokki, Cairo, Egypt
b National Research Centre, Photo Chemistry Department, 12622 Dokki, Cairo, Egypt
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of fused and non fused 1,2,4-triazoles with (2,4-dichlorophenoxy) moiety are prepared utilizing
3-((2,4-dichlorophenoxy)methyl)-4-amino-4H-1,2,4-triazole-5-thiol (3). The latter on reaction with
carboxylic acids, ethylchloroformate, ethylcyanoacetate and sodium nitrite gives five membered fused
triazole derivatives 4a–d, 5, 6, 7 and 10, respectively. The six membered heterocycles 11, 12 and 14 are
Received 27 October 2009
Received in revised form
14 January 2010
Accepted 15 January 2010
Available online 21 January 2010
prepared by cyclization of compound 3 with phenacyl bromide, chloroacetic acid and a-bromoketone
respectively. Most of the newly synthesized compounds were screened for their anti-inflammatory and
molluscicidal activities. The compounds 4b, 4d, 11 and 14 showed potent anti-inflammatory activities in
dose dependent manner while compounds 3, 4b, 8 and 10 exhibited promising molluscicidal activities.
Ó 2010 Elsevier Masson SAS. All rights reserved.
Keywords:
Triazolothiadiazole
Triazolothiadiazine
2,4-Dichlorophenoxyacetic acid
Triazoles
Molluscicidal
Anti-inflammatory activities
1. Introduction
Prompted by these observations, it was contemplated to
synthesize some newly N-bridged heterocycles containing (2,4-
1,2,4-Triazole derivatives are known to exhibit antibacterial,
antifungal [1], antitubercular [2], anticancer [3], anticonvulsant [4],
anti-inflammatory [5], analgesic [6], and molluscicidal properties
[7–10]. Among the pharmacological profiles of 1,2,4-triazoles, their
antimicrobial, anticonvulsant, and antidepressant properties seem to
be best documented. The arrangement of three basic nitrogen atom in
the triazole ring induces antiviral activity in the compounds con-
taining a triazole ring [11]. The 1,2,4-triazole nucleus has been
incorporated into a wide variety of therapeutically interesting drug
candidates including H1/H2 histamine receptor blockers, cholines-
terase active agents, CNS stimulants, antianxiety, andsedatives agents
[12]. Some of the modern day drugs with triazole nucleus are Riba-
virin (antiviral agent), Alprazolam (anxiolytic agent), Fluconazole,
Itraconazole (antifungal agent) and Rizatriptan (antimigrane agent).
The ambient nucleophilic centers present in 3-substituted-4-
amino-5-mercapto-1,2,4-triazoles render them as useful synthons
for the synthesis of various N-bridged heterocycles. Moreover,
synthesis of triazole fused to other heterocycles has attracted
attention widely due to their diverse applications.
dichlorophenoxy) moiety (which possess an excellent herbicidal
activity) [13] with a view to explore their potency as better
chemotherapeutic agents. Some newly synthesized compounds
were screened for the anti-inflammatory and molluscicidal
activities.
2. Results and discussion
2.1. Chemistry
3-((2,4-Dichlorophenoxy)methyl)-4-amino-4H-1,2,4-triazole-5-
thiol (3), was prepared according to a methodology involves the
condensation of 2,4-dichlorophenoxyacetic acid hydrazide (1) with
carbon disulfide and potassium hydroxide to yield the potassium
dithiocarbazate 2 which, after s-alkylation with methyl iodide,
underwent ring closure with an excess of hydrazine to produce the
aminothiol 3 in good yield [14].
Cyclocondensation of the SH and NH2 functions of 3 with aromatic
carboxylic acids and oxalic acid in the presence of phosphoryl chloride,
to give 3-((2,4-dichlorophenoxy)methyl)-6-aryl-s-triazolo[3,4-b]-
1,3,4-thiadiazoles 4a–d and bis(3-(2,4-dichlorophenoxy)methyl)-
6,60-s-triazolo[3,4-b][1,3,4]thiadiazole 5, respectively. The structure
of the isolated products 4a–d and 5 was elucidated on the basis of
* Corresponding author. Tel.: þ202 333 711211x1428; fax: þ202 33370931.
E-mail address: e_misbah@yahoo.co.uk (E.M. El-Telbani).
0223-5234/$ – see front matter Ó 2010 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2010.01.030

M.F. El Shehry et al. / European Journal of Medicinal Chemistry 45 (2010) 1906–1911
1907
N
N
O
O
+
CS2 / KOH
R
R C NH NHCSS K
R C NH NH2
N
S
2
1
N
8
COOEt
HON
N
MeI / N2H4
NaNO2
AcOH
N
N
N
N
N
NCCH2COOEt
ArCOOH
POCl3
R
R
R
SH
N
S
N
S
PPA
N
NH2
N
N
ClCOOEt
3
Ar
COOEt
4a-d
7
CH3ONa
oxalic acid
POCl3
Ar: a = 2,4-NO2C6H3
b = 4-OCH3C6H4
c = 2-furyl
N
N
N
N
d = 2,4-dichlorophenoxy
R
R
N
S
Cl
N
S
Cl
O
R =
HN
6
N
2
O
5
Scheme 1. Synthesis of triazolo-thiadiazole derivatives 4a–d–8.
their spectral (MS, IR and 1H NMR) and elemental analyses data. (cf.
Scheme 1 and Tables 1 and 2).
the presence of acetic acid, afforded hydroxyimino derivative 8 in
fairly good yield.
Compound 3 reacted with ethylchloroformate in the presence of
sodium methoxide affording a cyclized product, 3-((2,4-dichlor-
ophenoxy)methyl)-1,2,4-triazolo[3,4-b][1,3,4]thiadiazol-6(5H)-one
(6) in good yield. Treatment of 3 with ethylcyanoacetate in
polyphosphoric acid afforded triazolo[3,4-b][1,3,4]thiadiazole
derivative 7 in good yield. Nitrosation of 7 with sodium nitrite in
When compound 3 was treated with some aromatic aldehydes
namely, benzaldehyde, 2,4-dichlorobenzaldehyde and 3-(benzo-
furan-2-yl)-1-phenyl-1H-pyrazole-4-carbaldehyde;
a Schiff base
derivatives 9a–c were obtained in good yields. Reaction of 3 with
sodium nitrite in hydrochloric acid, give s-triazolo[3,4-b][1,3,4]thia-
triazole 10.
3-((2,4-Dichlorophenoxy)methyl)-6-phenyl-7H-[1,2,4]triazolo
[3,4-b][1,3,4]thiadiazine (11) was successfully achieved on treat-
ment of 3 with equimolar amounts of phenacyl bromide in
refluxing absolute ethanol. Structure 11 was deduced from micro-
analytical and spectral data.
Table 1
Physical constants of newly synthesized compounds.
Compd. Yield m.p. (ꢀC) Mol. form. (Mol. wt)
no.
Microanalysis
(%)
C
H
N
Chloroacetic acid in the presence of sodium acetate reacts with 3
affording in one step 3-((2,4-dichlorophenoxy)methyl)-5H-1,2,4-
triazolo[3,4-b][1,3,4] thiadiazine-6-(7H)-one (12). On the other
4a
(77)
215–217 C16H8Cl2N6O5S (467.24)
247–249 C17H12Cl2N4O2S (407.27)
207–209 C14H8Cl2N4O2S (367.21)
41.13 1.73 17.99
41.22 1.88 17.80
50.13 2.97 13.76
50.01 2.79 13.86
45.79 2.20 15.26
45.87 2.12 15.38
42.88 2.12 11.77
42.79 2.20 11.68
4b
4c
4d
5
(70)
(60)
(55)
(60)
(50)
(40)
(60)
(70)
(60)
(77)
(65)
(55)
(60)
(70)
hand, when 3 was treated with a-bromopropenone derivative 13
[15] in the presence of potassium hydroxide in ethanol, the aryli-
denetriazolothiadiazine 14 was formed in good yield. Both spectral
and elemental analyses were in accord with the suggested struc-
ture. (cf. Scheme 2 and Tables 1 and 2).
176–178
C17H10Cl4N4O2S (476.16)
162–164 C20H10Cl4N8O2S2 (600.29) 40.02 1.68 18.67
40.13 1.76 18.58
187–189 C10H6Cl2N4O2S (317.15)
6
37.87 1.91 17.67
37.94 1.84 17.74
43.42 3.12 14.47
43.33 3.04 14.58
40.40 2.66 16.83
40.32 2.73 16.77
50.67 3.19 14.77
50.59 3.26 14.68
42.88 2.25 12.50
42.94 2.17 12.58
57.76 3.23 14.97
57.68 3.30 14.88
35.54 2.32 23.03
35.60 2.25 23.11
52.18 3.09 14.32
52.11 3.17 14.26
39.89 2.43 16.92
39.96 2.37 16.88
63.34 3.16 11.98
63.41 3.09 11.92
2.2. Pharmaclogical screening
7
178–180 C14H12Cl2N4O3S (387.24)
2.2.1. Molluscicidal activity
8
184–186
C14H11Cl2N5O4S (416.24)
The toxicity of compounds 3, 4a–d, 5, 6, 7, 8, 9a–c, 10, 11, 12 and
14 toward Biomphalaria alexandrina snails was evaluated. An
insight inspection of the results listed in (Table 3) shows that
compounds 3, 4b, 8 and 10 have high effect on the snails but all the
other compounds have moderate to low effects on the snails, and
they all showed very weak activity below 5 ppm. A data obtained
showed promising results especially compounds possess a triazolo-
thiatriazole moiety and hydroxyimino residue and this data was in
a good agreement with previous reports [7–10].
9a
9b
9c
10
11
12
14
118–120 C16H12Cl2N4OS (379.26)
149–151 C16H10Cl4N4OS (448.15)
252–254 C27H18Cl2N6O2S (561.44)
171–173 (C9H5Cl2N5OS (304.16)
214–216 C17H12Cl2N4OS (391.27)
179–181 C11H8Cl2N4O2S (331.18)
235–237 C37H22Cl2N6O3S (701.58)
A
comparison of the molluscicidal activity of the new
compounds reported here with the international standard 20,5-
dichloro-4-nitrosalicylanilide (Bayluscide) [16,17]; showed that our
compounds are still far inferior as molluscicidal agents.

1908
M.F. El Shehry et al. / European Journal of Medicinal Chemistry 45 (2010) 1906–1911
Table 2
Mass, IR, 1H NMR spectral data of newly synthesized compounds.
Compd.
no.
Mass (m/z) (%)
IR (
n
, cmꢁ1
)
1H NMR (
d
, ppm) (DMSO-d6)
4a
4b
4c
[M]þ, 466 (30)
[M]þ, 406 (60)
[M]þ, 366 (38)
1600 (C]N), 2970, 2950 (CH aryl)
1594 (C]N). 2975, 2960 (CH aryl)
d
d
d
5.77 (s, 2H, CH2 phenoxy), 7.45–7.60 (m, 6H, Ar-H)
3.64 (s, 3H, CH3), 5.70 (s, 2H, CH2 phenoxy), 7.16–7.93 (m, 7H, Ar-H)
5.68 (s, 2H, CH2 phenoxy), 6.85–6.88 (m, 1H, furyl H-4), 7.45–7.63 (m, 4H, Ar-H and furyl H-3),
8.12–8.16 (m, 1H, furyl H-5)
4d
5
6
[M]þ, 474 (45)
[M]þ, 598 (50)
[M]þ, 316 (63)
[M]þ, 386 (35)
d
d
d
d
5.69 (s, 2H, CH2 phenoxy), 5.74 (s, 2H, CH2 phenoxy), 7.41–7.71 (m, 6H, Ar-H)
5.60 (s, 2H, CH2 phenoxy), 5.65 (s, 2H, CH2 phenoxy), 7.21–7.62 (m, 6H, Ar-H)
5.23 (s, 2H, CH2 phenoxy), 7.31–7.58 (m, 3H, Ar-H), 13.87 (s, 1H, NH)
1640 (CO), 3120 (NH)
7
1.28 (m, 3H, CH3), 4.15 (m, 2H, CH2ester), 4.41 (s, 2H, CH2), 5.71 (s, 2H, CH2 phenoxy),
7.31–7.72 (m, 3H, Ar-H)
1.31 (t, 3H, CH3), 4.24 (q, 2H, CH2ester), 5.21 (s, 2H, CH2 phenoxy), 7.35–7.81 (m, 3H, Ar-H),
10.63 (s, 1H, OH)
8
[M]þ, 415 (35)
[M]þ, 378 (63)
[M]þ, 446 (74)
[M]þ, 560 (70)
d
9a
9b
9c
1268–1248 (C]S), 1590 (C]N),
2955, 2980 (CH aryl), 3210 (NH)
d
d
5.40 (s, 2H, CH2 phenoxy), 7.38–7.77 (m, 8H, Ar-H), 8.12 (s, 1H, N]CH), 11.85 (br.s, 1H, NH)
5.48 (s, 2H, CH2 phenoxy), 7.43–7.93 (m, 6H, Ar-H), 8.00 (s, 1H, N]CH),
10.84 (br.s, 1H, NH)
5.45 (s, 2H, CH2 phenoxy), 7.35–7.64 (m, 13H, Ar-H and furan H-2), 8.10 (s, 1H, N]CH),
9.24 (s, 1H, pyrazole H-3), 10.47 (br.s, 1H, NH)
d
10
11
12
[M]þ, 303 (54)
[M]þ, 390 (80)
[M]þ, 330 (70)
d
d
d
5.23 (s, 2H, CH2 phenoxy), 7.31–7.58 (m, 3H, Ar-H)
4.45 (s, 2H, thiadiazin CH2), 5.51 (s, 2H, CH2 phenoxy), 7.39–7.95 (m, 8H, Ar-H)
5.22 (s, 2H, thiadiazinone CH2), 5.63 (s, 2H, CH2 phenoxy), 7.32–7.60 (m, 3H, Ar-H),
1686 (CO), 3200 (NH)
13.86 (br.s, 1H, NH)
14
[M]þ, 700 (50)
d
5.34 (s, 2H, CH2 phenoxy), 7.14–8.11 (m, 19H, Ar-H and methylene H)
2.2.2. Anti-inflammatory activity
3. Experimental
The anti-inflammatory activity of the synthesized compounds
(Table 4) was evaluated by carrageenan-induced paw oedema
method of Winter and Nuss [18]. Compounds 4b, 4d, 11, 14 showed
significant anti-inflammatoryeffect, whichprotected rats by36–56%
from inflammation other tested compounds did not show any
significant anti-inflammatory effect which might be permeated to
their solubility issue (DMSO is not physiologically accepted solvent
for in vivo experiment; and accordingly it was used with limitation).
From the viewpointof structure activity relationship (SAR), it is clear
that the triazolothiadiazole derivatives having 2,4-dichlorophenoxy
4d and 4-methoxyphenyl 4b at C-6 position possess highest activity
compared with indomethacin. Moreover, the triazolothiadiazine
derivatives having 2,4-dichlorophenoxy at C-3 and phenyl or ben-
zofuryl at C-6 positions having significant activity. The obtained
results were in accordance with previous reports [19,20].
3.1. General
All melting points were determined on an Electrothermal 9100
digital melting point apparatus. IR, 1H NMR and mass spectra were
recorded on: IR spectra (KBr): Pye-Unicam SP-1100.1H NMR spectra:
Jeol GLM EX 270 MHz FT NMR spectrophotometer, DMSO-d6, TMS as
internal standard, chemical shift in
d (ppm). Mass spectra: 70 eV,
Varian MAT 311 A. Elemental analysis (in accord with the calculated
values) was carried out in the microanalytical unit, Faculty of
Science, Cairo University. Yields are not optimized. Anti-inflamma-
tory activities were carried out at pharmacology unit, National
Research Centre. 2,4-Dichlorophenoxyacetic acid hydrazide 1 and 4-
amino-5-((2,4-dichlorophenoxy) methyl)-4H-1,2,4-triazole-3-thiol
3 were prepared as previously described [14].
N
N
N
N
N
N
R
R
R
S
S
N
N
S
N
N
N
N
HN
11
10
12
O
Ph
PhCOCH2Br
EtOH
°
0 C
O
N
N
N
N
N
NH
Ar
13
Ar`
Br
ArCHO
AcOH
R
R
S
SH
R
S
N
N
NH2
N
KOH/EtOH
Ar`
N
N CH Ar
9a-c
3
14
Ar
Ar: a = Ph
b = 2,4-(Cl)2C6H3
N
Ar ` =
Ar =
Ph
N
Cl
O
c =
Cl
O
R =
N
Ph
N
O
O
Scheme 2. Synthesis of triazolo-thiadiazine derivatives.

M.F. El Shehry et al. / European Journal of Medicinal Chemistry 45 (2010) 1906–1911
1909
Table 3
3.2.4. 3,6-Bis((2,4-dichlorophenoxy)methyl)-[1,2,4]triazolo[3,4-b]-
[1,3,4]thiadiazole (4d)
The compound was obtained from the reaction of 2,4-dichlor-
ophenoxyacetic acid (10 mmol), as white solid (EtOH).
Molluscicidal activity of compounds 3, 4a–d and 5–14 on Biomphalaria alexandrina
snails (10 snails by concentrations) under Laboratory conditions and after 24 h
exposure.
Compd. No.
Different concentration used in (ppm)
1
5
10
3.3. 3-((2,4-Dichlorophenoxy)methyl)-6-(3-((2,4-dichloro-
phenoxy)methyl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazol-6-yl)-
[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole (5)
3
4a
4b
4c
4d
5
6
7
8
9a
9b
9c
10
11
12
14
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
6
1
3
1
0
2
2
0
3
0
1
0
5
3
2
1
10
5
7
6
3
6
5
4
8
3
5
4
10
6
5
5
10
Compound 5 was synthesized from 3 (20 mmol) and oxalic acid
(10 mmol) in a manner similar to that described for 4a–d as white
solid (EtOH).
3.4. 3-((2,4-Dichlorophenoxy)methyl)-[1,2,4]triazolo[3,4-b]-
[1,3,4]thiadiazol-6(5H)-one (6)
To 3 (10 mmol), sodium methoxide (10 mmol) in (50 mL)
methanol and ethylchloroformate (10 mmol) was added. The reac-
tion mixture was refluxed for 5 h, then evaporated under vacuum,
the solid obtained washed with water and recrystallized to yield 6 as
white solid (EtOH).
Bayluscide
10
10
3.5. Ethyl-2-(3-((2,4-dichlorophenoxy)methyl)-[1,2,4]triazolo[3,4-b]-
3.2. General procedure for synthesizing of (4a–d)
[1,3,4]thiadiazol-6-yl)acetate (7)
A mixture of 3 (10 mmol) and aromatic acids (10 mmol) in the
presence of POCl3 (15 mL) was refluxed for 2–3 h. After removal of
the excess of POCl3 under reduced pressure, the residual added to
crushed ice and the mixture stirred at room temperature for 1 h.
During this time the solution was gradually neutralized with
(Na2CO3), the solid product was filtered off, washed with water,
dried and recrystallized from appropriate solvent to afford the title
compounds.
A mixture of 3 (10 mmol) and ethylcyanoacetate (10 mmol) in
PPA (15 mL) was stirred at 60 ꢀC for 6 h. After cooling the reaction
mixture was added to crushed ice and the mixture stirred at room
temperature for 1 h. During this time the solution was gradually
neutralized with NaHCO3. The solid product was filtered off,
washed with water, dried and recrystallized to give 7 as white solid
(EtOH).
3.2.1. 3-((2,4-Dichlorophenoxy)methyl)-6-(2,4-dinitrophenyl)-
[1,2,4]triazolo[3,4-b][1,3,4] thiadiazole (4a)
3.6. Ethyl 2-(3-((2,4-dichlorophenoxy)methyl)-[1,2,4]triazolo[3,4-
b][1,3,4]thiadiazol-6-yl)-2-(hydroxyimino)acetate (8)
The compound was obtained from the reaction of 2,4-dini-
trobenzoic acid (10 mmol), as white solid (EtOH).
To a solution of 7 (10 mmol) in (20 mL) acetic acid, aqueous
sodium nitrite (20 mmol) was added portionwise, with stirring at
0–5 ꢀC, over a period of 20 min. After 3 h, the reaction mixture was
poured onto water, a precipitate was formed, filtered off, and
crystallized to give 8 as white solid (EtOH).
3.2.2. 3-((2,4-Dichlorophenoxy)methyl)-6-(4-methoxyphenyl)-
[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole (4b)
The compound was obtained from the reaction of 4-methoxy-
benzoic acid (10 mmol), as white solid (EtOH).
3.7. General procedure for synthesizing of (9a–c)
3.2.3. 3-((2,4-Dichlorophenoxy)methyl)-6-(furan-2-yl)-
[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole (4c)
The compound was obtained from the reaction of furan-2-
carboxylic acid (10 mmol), as white solid (EtOH).
A solution of 3 (10 mmol) in glacial acetic acid (10 mL) was
allowed to react with the appropriate aldehydes (10 mmol) under
reflux for 1 h. The reaction mixture was then cooled and the
Table 4
Anti-inflammatory activity of compounds 3, 4a–d and 10–14 against carrageenan-induced rat paw oedema over 4 h.
Group
(% Inhibition of oedema) ꢂ S.E.
1 h
2 h
3 h
4 h
3
4a
4b
4c
4d
10
11
14
(49.99675)a ꢂ 8.852533
(32.16216)a ꢂ 5.542188
(26.74506)b ꢂ 1.651259
(51.37782)a ꢂ 12.46712
(26.94604)b ꢂ 2.755955
(70.78083)a ꢂ 25.75219
(27.65508)b ꢂ 2.601153
(29.71395)b ꢂ 5.692312
(48.54701) ꢂ 4.955791
(24.80194)b ꢂ 15.32791
(60.30075)a ꢂ 6.318443
(66.06168)a ꢂ 16.70769
(46.22208)b ꢂ 10.17494
(54.62069)a ꢂ 12.6645
(48.39525)b ꢂ 7.749848
(94.79833)a ꢂ 22.14129
(45.62023)b ꢂ 5.10145
(41.31841)b ꢂ 6.448136
(66.60562) ꢂ 9.022303
(20.97271)b ꢂ 17.03966
(102.8511)a ꢂ 6.44741
(68.04117)a ꢂ 8.771818
(56.33506)b ꢂ 9.240293
(99.24333)a ꢂ 13.43806
(63.15481)b ꢂ 7.584049
(108.482)a ꢂ 37.94043
(60.42211)b ꢂ 7.215277
(59.66482)b ꢂ 12.636069
(72.88156) ꢂ 10.1965
(26.28741)b ꢂ 15.27344
(81.74565)a ꢂ 13.4234
(63.95059)a ꢂ 6.462582
(44.33871)b ꢂ 9.676857
(93.97222)a ꢂ 20.89291
(58.48116)b ꢂ 6.456058
(74.03251)a ꢂ 19.40933
(48.51348)b ꢂ 10.54937
(35.77512)b ꢂ 9.791311
(72.97924) ꢂ 14.61699
(20.19146)b ꢂ 17.59208
Cont
Indomethacin
Values represent the mean ꢂ S.E. of six animals for each group. Data were analyzed by One-way T-test using Indomethacin as anti-inflammatory standard agent.
a
Represents not significance level at P < 0.05.
Represents the significance level at P < 0.05.
b

1910
M.F. El Shehry et al. / European Journal of Medicinal Chemistry 45 (2010) 1906–1911
precipitated arylidene derivatives were filtered off, washed with
water, dried and recrystallized from appropriate solvent to afford
the title compounds.
shell diameter) were collected from the field (water canals) and
maintained under laboratory conditions for a period of 10 days
before the test and fed daily by lettuce leaves. Three concentrations
of each compound under investigation were prepared ranging
from 1 to 10 ppm. The required amount of the compound under
investigation was mixed thoroughly with few drops of Tween 20
and 2 mL of DMSO to render the compounds completely soluble,
followed by addition of the appropriate volume of untreated raw
water (taken directly from the Nile River or its subsidiary
branches/canals) to get a homogeneous suspension with the
requisite concentration and placed in glass jar vessels 15 ꢃ 25 ꢃ 20
cm dimensions fitted with air bubblers. Ten snails were used in
each experiment and maintained in the test solution under labo-
ratory conditions at 25 ꢀC for 24 h. Each experiment was repeated
three times, and the mean number of killed snails was taken for
each concentration (Table 3). A control group was taken by placing
10 snails in water containing few drops of Tween 20 and 2 mL of
DMSO. Bayluscide was used as a reference molluscicidal agent.
These bioassays are in accordance with the W.H.O guidelines [21]
slightly modified by using two mixed solvents to dissolve the
compounds.
3.7.1. 5-((2,4-Dichlorophenoxy)methyl)-4-(benzylideneamino)-2H-
1,2,4-triazole-3(4H)-thione (9a)
The compound was obtained from the reaction of benzaldehyde
(10 mmol), as white solid (EtOH).
3.7.2. 4-(2,4-Dichlorobenzylideneamino)-5-((2,4-dichloro-
phenoxy)methyl)-2H-1,2,4-triazole-3(4H)-thione (9b)
The compound was obtained from the reaction of 2,4-dichlor-
obenzaldehyde (10 mmol), as white solid (EtOH).
3.7.3. 4-((3-(Benzofuran-2-yl)-1-phenyl-1H-pyrazol-4-yl)methyl-
eneamino)-5-((2,4-dichlorophenoxy)methyl)-2H-1,2,4-triazole-
3(4H)-thione (9c)
The compound was obtained from the reaction of 3-(benzo-
furan-2-yl)-1-phenyl-1H-pyrazole-4-carbaldehyde (10 mmol), as
white solid (MeOH).
3.8. 4-((2,4-Dichlorophenoxy)methyl)-[1,2,4]triazolo[4,3-d]-
[1,2,3,4]thiatriazole (10)
4.2. Methodology of anti-inflammatory activity
A solution of 3 (10 mmol) in HCl (50 mL) was cooled to 0 ꢀC and
a cold solution of sodium nitrite (10 mmol) in water (10 mL) was
gradually added. The reaction mixture was kept at 0–5 ꢀC with
stirring for 2 h, left overnight and diluted with water where upon
precipitation took place. The solid that precipitated was collected
and recrystallized to give 10 as white solid (EtOH).
1 h after drug oral administration, rats weighting z200 gm each
were injected subplanter into the hind left paw with 1 mg carra-
geenan dissolved in 100 mL physiological solution. Paw volumes
were measured every hour using standard fluid displacement
procedures (plethysmometer) by dipping the hind left paw in 0.45%
saline solution every 1 h interval for total of 4 h. The percent change
in paw volume compared to base line measurement was taken as
the criteria of comparison. Indomethacin was used as an internal
standard anti-inflammatory agent. The method adopted resembles
essentially that described by Winter et al. (Table 4).
3.9. 3-((2,4-Dichlorophenoxy)methyl)-6-phenyl-7H-
[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine (11)
A mixture of 3 (10 mmol) and phenacyl bromide (10 mmol) in
absolute ethanol (50 mL) was refluxed for 8 h. The solvent was then
removed by distillation and the remaining residue was washed
with water, filtered, dried and recrystallized to give 11 as white
solid (EtOH).
5. Conclusions
In summary, a series of new s-triazole and fused triazole
derivatives carrying the 2,4-dichlorophenoxy moiety (2,4-D) could
be synthesized and evaluated for their anti-inflammatory and
molluscicidal activities. Some of triazolothiadiazole and tri-
azolothiadiazine showed highly significant anti-inflammatory
effect, which protected rats by 36–56% from inflammation as
compounds 4b, 4d, 11, 14 comparable to the standard (Indometh-
acin). The compounds 4b, 8 and 10 showed potent molluscicidal
activities as compared to the standard molluscicidal agent
(Bayluscide).
3.10. 3-((2,4-Dichlorophenoxy)methyl)-5H-[1,2,4]triazolo[3,4-b]-
[1,3,4]thiadiazin-6(7H)-one (12)
To 3 (10 mmol) in acetic acid (50 mL), chloroacetic acid (20
mmol) and fused sodium acetate (15 mmol) were added. The
reaction mixture was refluxed for 6 h, cooled and the solid obtained
filtered off, washed with water, and recrystallized to give 12 as
white solid (EtOH).
References
3.11. 3-((2,4-Dichlorophenoxy)methyl)-7-((3-(benzofuran-2-yl)-1-
phenyl-1H-pyrazol-4-yl)methylene)-6-(benzofuran-3-yl)-7H-
[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine (14)
[1] G.T. Zitoun, Z.A. Kaplancikl, M.T. Yildiz, P. Chevallet, D. Kaya, Eur. J. Med. Chem.
40 (2005) 607.
[2] K. Walczak, A. Gondela, J. Suwinsk, Eur. J. Med. Chem. 39 (2004) 849.
[3] B.S. Holla, B. Veerendra, M.K. Shivananda, B. Poojary, Eur. J. Med. Chem. 38
(2003) 759.
[4] M. Amir, K. Shikha, Eur. J. Med. Chem. 39 (2004) 535.
[5] A. Almasirad, S.A. Tabatabai, M. Faizi, A. Kebria, N. Mehrabi, A. Dalavand,
A. Shafiee, Bioorg. Med. Chem. 14 (2004) 6057.
A mixture of 3 (10 mmol), 1,3-diaryl-2-bromo-2-propen-1-ones
13 (10 mmol), and ethanolic potassium hydroxide (15 mmol) was
refluxed in ethanol (15 mL) for 8 h. The precipitated solid was
filtered off, washed with water, and recrystallized to give 14 as
white solid (AcOH).
[6] D.V. Thomas George, R. Mehta, J.D. Tahilramani, P.K. Talwalker, J. Med. Chem.
14 (4) (1971) 335–338.
[7] G.A.M. Nawwar, B.M. Haggag, R.H. Swellem, Arch. Pharmacol. 326 (1993) 831.
[8] N. Grant, N. Mishriky, F.M. Asaad, N.G. Fawzy, Pharmazie 53 (1998) 543.
[9] N.A. Shafik, L.M. Chabaka, G.A.M. Nawwar, Afinidad 63 (2006) 523.
[10] G.A.M. Nawwar, L.M. Chabaka, N.A. Shafik, M.S. Hany, Afinidad 63 (2006) 153.
[11] K. Masuda, T. Toga, N. Hayash, J. Labelled Compd. 11 (1975) 301;
Chem. Abstr. 84 (1976) 121730f.
4. Biological screening
4.1. Molluscicidal activity tests
[12] E. Schreier, Helv. Chim. Acta 59 (1976) 585.
[13] C.R. Worthing, The Pesticide Manual a World Compendium, eighth ed. The
British Crop Protection Council, 1987, p. 150 and 840.
The molluscicidal activity tests were carried out for each
compound under investigation. B. alexandrina snails (ca. 7 mm

M.F. El Shehry et al. / European Journal of Medicinal Chemistry 45 (2010) 1906–1911
1911
[14] J.R. Reid, N.D. Heindel, J. Heterocycl. Chem. 13 (1976) 925.
[19] B. Tozkoparan, S.P. Aytac, G. Aktay, Arch. Pharm. Chem. Life Sci. 342 (2009)
291–298.
[20] M. Amir, H. Kumar, S.A. Javed, Eur. J. Med. Chem. 43 (2008) 2056–2066.
[21] WHO, World Health Organisation: The Control of Schistosomiasis, Geneva,
(WHO Technical Report Series, No. 830), 1993.
[15] M.S. Karthikeyn, B.S. Holla, S. Shenoy, Monatsh Chem. 139 (2008) 707.
[16] P. Andrews, J. Thyseen, D. Lorke, Pharmacol. Ther. 19 (1983) 245–295.
[17] WHO, Niclosamide Technical Material, WHO Specifications, 2002, p. 599.
[18] E.A.R. Winter, G.W. Nuss, Proc. Soc. Exp. Biol. Med. III (1962) 544–547.