Synthesis and biological evaluation of some [1,2,4]triazolo[3,4-b][1,3,4] thiadiazoles and [1,2,4]triazolo[3,4-b][1,3,4]thiadiazines

Article abstract of DOI:10.2174/157018011794183806

The reaction of 2-(aryloxymethyl)benzoic acid hydrazide with carbon disulfide in the presence of potassium hydroxide followed by hydrazine hydrate afforded 4-amino-3{2-(aryloxymethyl)pheny}[1,2,4]triazole-5-thiol (5a-d). The cyclo-condensation of 5a-d with various aromatic carboxylic acids in the presence of phosphorous oxychloride and with phenacyl bromides afforded two series of fused heterocycles namely; 6-substituted-3-{2-(aryloxymethyl)phenyl}- 1,2,4- triazolo[3,4-b][1,3,4]thiadizoles (6a-t) and 6-substituted-3-{2- (aryloxymethyl)phenyl)}[1,2,4]triazolo[3,4-b][1,3,4] thiadiazines (7a-p) respectively. The structures of these newly synthesized compounds were established on the basis of their IR, ¹H-NMR ¹³C-NMR and Mass spectral data. All the title compounds were screened for their antimicrobial and antiinflammatory activities. Preliminary results indicated that some of them exhibit promising activities and they deserve more consideration as potential antimicrobial and anti-inflammatory agents.

Full text of DOI:10.2174/157018011794183806

Letters in Drug Design & Discovery, 2011, 8, 189-200
189
Synthesis and Biological Evaluation of Some [1,2,4]Triazolo[3,4-
b][1,3,4]Thiadiazoles and [1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazines
Channamata Shankara Naveenaa,b, Boja Poojary*,a, Chikkanna Chandrashekharc and
Nalilu Suchetha Kumarid
aDepartment of Chemistry, Mangalore University, Mangalagangothri-575199, Karnataka, India
bSeQuent Scientific Limited, New Mangalore-575011, Karnataka, India
cDepartment of Medicinal Chemistry, S D M College, Ujire-574162, Karnataka, India
dDepartment of Biochemistry, K. S. Hegde Medical Academy, Deralakatte-574162, Karnataka, India
Received July 09, 2010: Revised October 21, 2010: Accepted October 27, 2010
Abstract: The reaction of 2-(aryloxymethyl)benzoic acid hydrazide with carbon disulfide in the presence of potassium
hydroxide followed by hydrazine hydrate afforded 4-amino-3{2-(aryloxymethyl)pheny}[1,2,4]triazole-5-thiol (5a-d). The
cyclo-condensation of 5a-d with various aromatic carboxylic acids in the presence of phosphorous oxychloride and with
phenacyl bromides afforded two series of fused heterocycles namely; 6-substituted-3-{2-(aryloxymethyl)phenyl}-1,2,4-
triazolo[3,4-b][1,3,4]thiadizoles (6a-t) and 6-substituted-3-{2-(aryloxymethyl)phenyl)}[1,2,4]triazolo[3,4-b][1,3,4] thia-
diazines (7a-p) respectively. The structures of these newly synthesized compounds were established on the basis of their
1
IR, H-NMR 13C-NMR and Mass spectral data. All the title compounds were screened for their antimicrobial and anti-
inflammatory activities. Preliminary results indicated that some of them exhibit promising activities and they deserve
more consideration as potential antimicrobial and anti-inflammatory agents.
Keywords: Triazolothiadiazoles, Triazolothiadiazines, N-Bridged condensed heterocycle, 2-(Aryloxymethyl)phenyl moiety,
Antimicrobial activity, Anti-inflammatory activity.
INTRODUCTION
the 2-(aryloxymethyl) benzoic acid ethylesters (2a-2d) were
conveniently converted to 2-(aryloxymethyl) benzoic acid
hydrazides (3a-3d) by refluxing them with hydrazine hydrate
in propanol. The compound (3a-3d) on reaction with carbon
disulphide in methanolic potassium hydroxide yielded
corresponding potassium dithiocarbazates (4a-4d) in good
yield. The required 4-amino-5-{2-(aryloxymethyl) phenyl}-
4H-[1,2,4]triazole-3-thioles (5a-5d) were synthesized by
refluxing (4a-4d) with aqueous hydrazine hydrate. Conden-
sation of (5a-5d) with various aromatic carboxylic acids
in boiling phosphorous oxychloride yielded 6-substituted-3-
{2-(aryloxymethyl)phenyl}-[1,2,4]triazolo[3,4-b][1,3,4]thi-
Various [1, 2, 4] triazolo[3,4-b][1,3,4]thiadiazoles and
[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines possess a wide range
of biological activities, such as antimicrobial [1-6], Anti-
hypertensive [7], anti-inflammatory [8,9] and anticancer [10,
11] effects. The synthesis of triazoles fused to another het-
erocyclic ring has attracted particular attention due to their
diverse applications as antibacterial, antidepressant, antiviral,
anti-HIV-1, antitumor, anti-inflammatory agents, pesticides,
herbicides, lubricant, analytical reagents, etc [12-14]. A
number of triazoles fused to thiadiazines or thiadiazoles are
incorporated into a wide variety of therapeutically important
compounds possessing a broad spectrum of biological activi-
ties [15-20]. The present study describes the synthesis
of a series of 6-aryl-3-{2-(aryloxymethyl)phenyl}-[1, 2,
4]triazolo[3, 4-b] [1, 3, 4] thiadiazoles (6a-6t) and 6-aryl-3-
{2-(aryloxymethyl) phenyl}-1, 2, 4-triazolo [3, 4-b][1, 3,
4]thiadiazines (7a-7p) from 5-substituted-4-amino-4H-[1, 2,
4] triazole-3-thioles (5a-5d) (Fig. 1) and evaluation of their
antimicrobial and anti-inflammatory activities.
adizoles
(6a-6t).
6-Substituted-3-{2-(aryloxymethyl)
phenyl}-[1,2,4]triazolo[3,4-b] [1,3,4]thiadiazines (7a-7p)
were synthesized by the cyclocondensation of various phen-
acyl bromides with (5a-5d) in refluxing ethanol.
The structural assignments to new compounds were
based on their elemental analyses and spectral (IR, 1H-NMR
13C-NMR and MASS) data. The characterization data of all
the new compounds are summarized in Table 1. The forma-
tion of 2-(aryloxymethyl) benzoic acid hydrazide (3d) from
2-(aryloxymethyl) benzoic acid ethyl ester (2d) was con-
firmed by its elemental analyses and spectral data. Its spec-
trum showed absorption bands at 3291, 3224, 3070, 1688
and 1544 cm-1 due to –NH2, -NH, Ar-CH3, >C=O, and
RESULTS AND DISCUSSION
Chemistry
1
The reaction sequences employed for the synthesis of ti-
tle compounds are shown in Scheme1. The key intermediate,
>C=C< groups respectively, while H-NMR showed sharp
singlets at ꢀ 4.07 and ꢀ 5.22, which correspond to -NH2 and
–OCH2 protons respectively. Two doublets observed at ꢀ
6.92 (J = 7.2 Hz) and ꢀ 6.25 (J = 7.2 Hz) accounted for the
four aromatic protons of ring A. The ring B protons appeared
*Address correspondence to this author at the Department of Chemistry,
Mangalore University, Mangalagangothri-575199, Karnataka, India;
Tel/Fax: +91-824-2287262/2287367; E-mail: bojapoojary@gmail.com
1570-1808/11 $58.00+.00
© 2011 Bentham Science Publishers Ltd.

190 Letters in Drug Design & Discovery, 2011, Vol. 8, No. 2
Naveena et al.
Fig. (1). General structures of 1,2,4-triazolo[3,4-b]1,3,4]thiadiazoles and [1,2,4]triazolo[3,4-b][1,3,4] thiadiazines
R
Ar
-
Arꢀ
1a-5a
2-CH3
-
1b-5b
1c-5c
1d-5d
6a-t
3-CH3
4-CH3
4-Cl
2-CH3, 3-CH3,
4-CH3, 4-Cl
2-CH3, 3-CH3,
4-CH3, 4-Cl
-
-
-
-
-
-
-
2-Cl-pyridin-3-yl, 3,5-(CH3)2-C6H3 , 3,5-Cl2-C6H3,
3,4,5-(OCH3)3-C6H2, 3-Br-C6H4,
-
7a-p
3-CONH2-4-OH-C6H3, 5-Cl-2-SO2NH2-3-thienyl,
3-Br-C6H4, 4-NO2-C6H4
Scheme 1.
as a multiplet in the region ꢀ 7.48-7.58 integrating for four
protons. The spectrum also showed a broad singlet at ꢀ 7.40
for its NH protons. The potassium dithiocarbazate (4a) was
directly used for the next step without characterization. Fur-
ther, the cyclization of (4a) to 4-amino-3{2-(aryloxy-
methyl)}[1,2,4]triazole-5-thiole (5a) was confirmed by re-
cording its IR spectrum, which showed absorption bands at
3313, 2667 and 1617 cm-1 due to its -NH2, -SH, and C=N
respectively. The disappearance of characteristic absorption
band due to >C=O group of (4a) is clearly an indication of
its smooth cyclization to afford (5a). Its H-NMR spectrum
showed two singlets at ꢀ 2.16, ꢀ 4.75 and ꢀ 5.20 which
1

[1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazoles and [1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazines
Letters in Drug Design & Discovery, 2011, Vol. 8, No. 2 191
Table 1. Physical Constants and Characterization Data of Compounds (6a-t) and (7a-p)
Elemental Analysis, % Found (calculated)
Mol.
Mass
Yield
(%)
MP
Compd
R
Ar
Mol. Formula
(0C)
C
H
N
6a
6b
2-CH3
3-CH3
2-Cl-pyridin-3-yl
2-Cl-pyridin-3-yl
C22H16ClN5OS
C22H16ClN5OS
433.9
433.9
65
63
140-142
110-112
60.84(60.90)
60.58(60.90)
3.65(3.72)
3.68(3.72)
16.10(16.14)
15.92 (16.14)
6c
6d
6e
4-CH3
4-Cl
2-Cl-pyridin-3-yl
2-Cl-pyridin-3-yl
3,5-(CH3)2C6H3
C22H16ClN5OS
C21H13 Cl2N5OS
C25H22N4OS
433.9
454.3
426.5
60
64
66
142-143
112-114
120-122
60.54(60.90)
56.35(55.52)
70.32(70.40)
3.62(3.72)
2.74 (2.88)
4.92 (5.20)
16.33 (16.14)
15.37(15.41)
13.28 (13.14)
2-CH3
6f
6g
6h
3-CH3
4-CH3
4-Cl
3,5(CH3)2C6H3
3,5(CH3)2C6H3
3,5(CH3)2C6H3
C25H22N4OS
C25H22N4OS
C24H19ClN4OS
426.5
426.5
446.9
63
68
66
106-107
112-115
129-131
69.92(70.40)
70.22(70.40)
64.40(64.49)
5.20 (5.20)
5.14 (5.20)
4.39(4.28)
13.10 (13.14)
12.88 (13.14)
12.38(12.54)
6i
2-CH3
3,4,5-(OCH3)3C6H2
C26H24N4O4S
488.5
67
102-104
64.80 (63.92)
4.52(4.95)
11.28(11.47)
6j
3-CH3
4-CH3
3,4,5-(OCH3)3C6H2
3,4,5-(OCH3)3C6H2
C26H24N4O4S
C26H24N4O4S
488.5
488.5
63
64
105-108
98-100
64.70 (63.92)
64.55 (63.92)
4.75(4.95)
4.02(4.16)
12.18(11.47)
11.38(11.47)
6k
6l
6m
6n
6o
4-Cl
3,4,5-(OCH3)3C6H2
3,5-Cl2-C6H3
C25H21ClN4O4S
C23H16Cl2N4OS
C23H16Cl2N4OS
C23H16Cl2N4OS
508.9
467.3
467.3
467.3
66
63
67
65
120-122
118-119
185-187
220-221
58.85 (58.99)
59.20 (59.11)
59.10 (59.11)
59.32 (59.11)
4.11 (4.16)
3.40 (3.45)
3.40 (3.45)
3.42 (3.45)
11.14 (11.01)
12.12 (11.99)
12.00 (11.99)
12.23 (11.99)
2-CH3
3-CH3
4-CH3
3,5-Cl2-C6H3
3,5-Cl2-C6H3
6p
4-Cl
3,5-Cl2-C6H3
C22H13Cl3N4OS
487.7
65
200-202
54.20 (54.17)
2.58 (2.69)
11.35 (11.49)
6q
6r
6s
6t
2-CH3
3-CH3
4-CH3
4-Cl
3-Br-C6H4
3-Br-C6H4
C23H17BrN4OS
C23H17BrN4OS
C23H17BrN4OS
C22H14BrClN4OS
C25H21N5O3S
477.3
477.3
477.3
497.7
471.5
65
65
65
68
72
196-198
170-171
110-112
180-181
218-220
57.52 (57.87)
57.74 (57.87)
57.66 (57.87)
53.12 (53.08)
63.48 (63.68)
3.42 (3.59)
3.50 (3.59)
3.52 (3.59)
2.78 (2.83)
4.33 (4.49)
11.33 (11.74)
11.58 (11.74)
11.62 (11.74)
11.19 (11.25)
14.82 (14.85)
3-Br-C6H4
3-Br-C6H4
7a
2-CH3
3-CONH2-4-OH- C6H3
7b
3-CH3
3-CONH2-4-OH- C6H3
C25H21N5O3S
471.5
74
214-216
63.36 (63.68)
4.40 (4.49)
14.85 (14.85)
7c
7d
7e
7f
4-CH3
4-Cl
3-CONH2-4-OH- C6H3
3-CONH2-4-OH- C6H3
5-Cl-2-SO2NH2-3-thienyl
5-Cl-2-SO2NH2-3-thienyl
5-Cl-2-SO2NH2-3-thienyl
5-Cl-2-SO2NH2-3-thienyl
C25H21N5O3S
C24H18ClN5O3S
C22H18ClN5O3S3
C22H18ClN5O3S3
C22H18ClN5O3S3
C21H15Cl2N5O3S3
471.5
491.9
532.0
532.0
532.0
552.4
74
76
68
70
67
70
224-228
238-240
224-226
170-172
150-154
192-195
63.18 (63.68)
58.54 (58.59)
49.46 (49.66)
49.23 (49.66)
49.72 (49.66)
45.38 (45.65)
4.33 (4.49)
3.52 (3.69)
3.32 (3.41)
3.52 (3.41)
3.32 (3.41)
2.72 (2.74)
14.36 (14.85)
14.11 (14.24)
12.88 (13.16)
13.05 (13.16)
12.92 (13.16)
12.42 (12.68)
2-CH3
3-CH3
4-CH3
4-Cl
7g
7h
7i
2-CH3
3-Br-C6H4
C24H19BrN4OS
491.4
68
170-172
58.24 (58.66)
3.75 (3.90)
11.27(11.40)
7j
7k
7l
3-CH3
4-CH3
4-Cl
3-Br-C6H4
3-Br-C6H4
3-Br-C6H4
4-NO2-C6H4
C24H19BrN4OS
C24H19BrN4OS
C23H16BrClN4OS
C24H19N5O3S
491.4
491.4
511.8
457.5
69
69
69
72
180-182
194-197
168-170
174-176
58.45 (58.66)
58.62 (58.66)
53.85 (53.97)
63.24 (63.01)
3.92 (3.90)
3.85 (3.90)
3.05 (3.15)
3.85 (4.19)
11.32(11.40)
11.42(11.40)
10.92(10.95 )
15.27(15.31)
7m
2-CH3
7n
7o
7p
3-CH3
4-CH3
4-Cl
4-NO2-C6H4
4-NO2-C6H4
4-NO2-C6H4
C24H19N5O3S
C24H19N5O3S
C23H16ClN5O3S
457.5
457.5
477.9
76
76
78
164-166
178-180
188-190
63.11 (63.01)
59.95 (63.01)
57.55 (57.80)
3.98 (4.19)
4.20 (4.19)
3.10 (3.37)
15.10(15.31)
15.22(15.31)
14.48(14.65)

192 Letters in Drug Design & Discovery, 2011, Vol. 8, No. 2
Naveena et al.
correspond to ring A-CH3, -NH2 and –OCH2 protons respec-
tively. A doublet at ꢀ 6.76 (J = 7.5 Hz) and a triplet at ꢀ 6.96
(J = 7.2 Hz) integrating for one proton each of ring A were
also seen along with a multiplet in the region ꢀ 7.07-7.12
integrating for remaining two protons. The four ring B pro-
tons appeared as a complex multiplet in the region ꢀ 7.44-
7.73. The sharp downfield singlet appearing at ꢀ 11.8 was
assigned to –SH proton. 13C-NMR spectrum of (5a) showed
signals at ꢀ 16.17, 67.96 due to ring A-CH3 and OCH2 car-
bon atoms respectively. The other peaks seen in the spectrum
were at ꢀ 111.8 and 121.0 (C2 and C3 of ring A), 123.0 and
126.8 (C6 and C4 of ring A), 126.8 (C4 of ring A), 127.8 (C1
of ring B), 128.5 and 130.9 (C2 and C5 of ring B), 130.9 and
131.3 (C4 and C3 of ring B), 137.8 (C6 of ring B), 150.3 (C5
of triazole), 156.2 (C1 of Ring A) and 166.91 (C3 of triazole
moiety) respectively. The peaks due to quaternary carbon
atoms of the compound disappeared on DEPT experimenta-
tion.
Hz) and 8.29 (J = 8.8 Hz) integrating for two protons each.
13C-NMR spectrum of (7o) showed signals at ꢀ 16.01, 23.08,
67.58 due to ring A-CH3, CH2 and OCH2 carbon atoms. The
other signals observed in the spectrum were ꢀ 110.8 (C2 and
C6 of ring A), 120.7 (C2 and C6 of ring C), 123.8 (C4 of ring
A), 124.2 (C2 of ring B), 126.7 (C4 of ring B), 126.8 (C1 of
ring C), 127.7 (C5 of ring B), 128.4 (C3 and C5 of ring C),
130.8 (C3 and C5 of ring A), 131.3 (C3 of ring B), 137.5 (C1
of ring B), 139.1 (C6 of ring B), 140.9 (C5 of triazole), 149.5
(C3 of triazole), 151.6 (C4 of ring C), 153.1(C1 of ring A) and
156.4 (C7 of thiadiazine) respectively. Further, LCMS of
(7o) showed the molecular ion peak as a base peak at m/z
457 which is in agreement with its molecular formula,
C24H19N5O3S3. Characterization data of (6a-6t) and (7a-7p)
are given in Table 1.
Antimicrobial Studies
The antimicrobial activity was determined using disc dif-
fusion method [21] by measuring zone of inhibition in mm.
All the compounds, (6a-6t) and (7a-7p) were screened in-
vitro at a concentration of 10 μg / disc for their antibacterial
activity against two Gram-positive strains (Staphylococcus
aureus and Bacillus subtilis) and two Gram-negative strains
(Escherichia coli and Pseudomonas aeruginosa). Antifungal
evaluation was also carried out against Candida albicans and
Aspergillus niger at a concentration of 10μg / disc. Standard
antibacterial drug ciprofloxacin (10μg / disc) and antifungal
drug fluconazole (10μg / disc) were also tested under similar
conditions against these organisms. All synthesized com-
pounds exhibited significant antibacterial activities and mod-
erate antifungal activities. Each experiment was done in trip-
licate and the average reading was taken. The antibacterial
activity was classified as highly active (ꢀ26 mm), moder-
ately active (11-25 mm) and least active (<11 mm). The re-
sults of antibacterial and antifungal activities are expressed
in terms of zone of inhibition and presented in Table 2.
The structural elucidation of title compound (6p) is based
1
on its IR, H-NMR, 13C-NMR and Mass spectral studies. IR
spectrum of (6p) showed absorption bands at 3055, 1612,
1284, 1074 and 756 cm-1 for its aromatic C-H, C=N, C=C,
1
C-S and C-Cl stretching vibrations respectively. In its H-
NMR spectrum, peaks due to -OCH2 protons appeared at ꢀ
5.55. The peaks due to ring A protons appeared as two dou-
blets at ꢀ 6.86 (J = 8.9 Hz) and 7.17 (J = 8.9 Hz) integrating
for two protons each. Three protons of ring C appeared at ꢀ
7.54-7.61 as a complex multiplet, while ring B protons ap-
peared as a complex multiplet in the region ꢀ 7.76-7.77 inte-
grating for two protons and the remaining two protons ap-
peared as two distinct doublets at ꢀ 7.83 (J = 7.2 Hz) and ꢀ
8.15 (J = 7.2 Hz). 13C-NMR spectrum of (6p) showed signals
at ꢀ 68.42 due to OCH2 carbon atom. Peaks also appeared at
ꢀ 116.3 (C2 and C6 of ring A), 122.7 (C3 of ring C), 125.4 (C2
and C6 of ring C), 125.8 (C5 of ring C), 127.9 (C4 of ring C),
128.1 (C3 and C5 of ring A), 128.9 (C2 of ring B), 129.3 (C5
of ring B), 130.8 (C4 of ring B), 131.9 (C1 of ring C), 132.6
(C3 of ring B), 136.5 (C4 of ring A), 136.8 (C1 of ring B),
146.4 (C6 of ring B), 153.7 (C3 and C5 of triazole), 157.6 (C1
of ring A) and 163.9 (C7 of thiadiazole ring) respectively.
The signals due to quaternary carbon atoms disappeared on
DEPT experimentation. The absence of characteristic IR
absorption bands due to –NH2 and -SH groups of (5d)
clearly confirmed condensation with acid to afford (6p). Fur-
ther, LCMS of (6p) showed the molecular ion peak as a base
peak at m/z 488, which is consistent with its molecular for-
mula, C22H13Cl3N4OS.
The investigation of antibacterial and antifungal screen-
ing data revealed that all the tested compounds (6a-6t) and
(7a-7p) showed moderate to good activity. The compounds
containing p-chlorophenoxy methylphenyl and 2-
chloronicotinyl (6d), 3,4,5-trimethoxyphenyl (6l), 3,5-
dichlorophenyl (6p), 2-hydroxy-4-carboxamidophenyl (7d),
and 5-chloro-2-sulfonamido phenyl (7h) moieties attached to
the thiadiazole and thiadiazine nuclei showed comparatively
good activity against all the bacterial strains. However, the
compounds 6a, 6b, 6c, 6h, 6i, 6j, 6k, 6m, 6n, 6o, 7a, 7b, 7c,
7e, 7f, 7g and 7p exhibited moderate activity compared to
that of standard against all bacterial strains.
The buildup of N-bridged condensed heterocycle (7o)
1
from (5c) is evidenced by its IR, H-NMR, 13C-NMR and
Mass spectral data. IR spectrum of (7o) indicated the pres-
ence of aromatic C-H, C=N, C-S stretching bands at 3055,
1616 and 1068 cm-1, respectively. The signals observed at ꢀ
2.07, 3.67 and 5.25 as singlets in its 1H-NMR spectrum con-
firmed the presence of ring A-CH3, -CH2 (thiadiazine ring)
and -OCH2 protons respectively. Ring A protons appeared as
two distinct doublets at ꢀ 6.70 (J = 8.1 Hz) and 7.05 (J = 8.1
Hz) integrating for two protons each. Two triplets at 7.48 (J
= 7.2 Hz) and 7.58 (J = 7.2 Hz) and also two distinct dou-
blets at ꢀ 7.68 (J = 7.2 Hz) and 7.73 (J = 7.2 Hz) for one
proton each of ring B were also seen in the spectrum. Ring C
protons appeared as two distinct doublets at ꢀ 7.89 (J = 8.8
The compounds having p-chlorophenoxy methylphenyl
and 3,4,5-trimethoxy- (6l), 3,5-dichloro- (6p) and 2-hydoxy-
4-carboxamido-phenyl (7h) groups attached to the thiadia-
zole and thiadiazine ring showed comparatively good growth
inhibition of all the fungal strains. On the other hand, com-
pounds 6d, 6h, 6i, 6j, 6k, 6m, 6n, 6o, 7d, 7e, 7f, 7g and 7p
exhibited moderate activity compared to that of standard
against C. albicans and A. niger. It has also been observed
that the thiadiazole derivatives are found to be more active
than thiadiazines. More extensive study is also warranted to
determine additional physicochemical and biological pa-
rameters to have a deeper insight into structure-activity rela-

[1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazoles and [1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazines
Letters in Drug Design & Discovery, 2011, Vol. 8, No. 2 193
Table 2. Antibacterial Activity Data of Compounds (6a-t) and (7a-p)
Zone of Inhition in mm
Antibacterial Activity
Antifungal Activity
Compd
A. niger
S. aureus
B. subtilis
E. coli
P. aeruginosa
C. albicans
6a
18
22
20
28
11
09
10
23
18
22
20
30
23
23
22
28
08
10
11
10
23
19
20
28
22
20
18
27
08
10
11
09
10
10
11
22
26
-
18
22
20
26
10
08
12
22
19
20
18
28
20
22
18
28
10
12
10
09
23
20
21
26
22
20
20
26
11
12
10
08
10
12
10
20
26
-
20
20
19
28
10
08
10
20
18
21
20
30
23
23
22
26
10
08
09
10
20
22
18
26
20
18
19
28
10
08
09
10
09
08
09
22
28
-
21
22
20
24
11
09
09
21
17
20
18
25
21
20
18
24
11
08
10
12
18
20
18
25
20
18
18
26
09
08
10
10
08
08
10
18
25
-
09
10
10
27
11
10
08
20
18
21
19
26
21
18
20
26
09
10
08
10
09
10
10
18
20
19
22
25
08
10
08
11
06
10
08
20
-
10
11
08
25
10
08
09
18
19
20
20
24
20
19
18
24
10
11
09
10
08
11
08
20
19
20
20
25
10
11
09
09
08
11
09
18
-
6b
6c
6d
6e
6f
6g
6h
6i
6j
6k
6l
6m
6n
6o
6p
6q
6r
6s
6t
7a
7b
7c
7d
7e
7f
7g
7h
7i
7j
7k
7l
7m
7n
7o
7p
Ciprofloxacin
Flucanazol
26
25
tionship and to optimize the effectiveness of this series of
molecules.
compared with the standard drug Diclofenac Sodium at the
same oral dose. The results were expressed as % inhibition
of oedema over the untreated control group (Table 3).
The tested compounds showed anti-inflammatory activity
ranging from 40.40 to 76.42 %, whereas standard drug
Diclofenac Na showed 75.93 % inhibition, after 3 h. The
anti-inflammatory activity of 1,2,4-triazolo[3,4-b][1,3,4]
thiadizoles (6a-6t) is in the range of 40.40-76.42 %. The
triazolothiadizole derivative having 4-chlorophenoxy-
methyphenyl and 2-chloropyridin-3-yl groups (6d) attached
Anti-Inflammatory Activity
The in vivo anti-inflammatory activity of all the newly
synthesized compounds was evaluated by carrageenan-
induced rat paw oedema method [22]. Wistar albino rats of
either sex weighing 180-250g were used for the experiment.
The compounds were tested at 10mg / kg oral dose and were

194 Letters in Drug Design & Discovery, 2011, Vol. 8, No. 2
Naveena et al.
Table 3. Antiinflammatory Activity Data of Compounds (6a-t) and (7a-p)
Compound
Dose (mg/kg Body Weight, p.o)
Increase in Paw Volume in ml MEAN ± SEM)
% Inhibition of Paw Oedema
6a
6b
6c
6d
6e
6f
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
0.0528±0.0017
0.0458±0.0028
0.0484±0.0023
0.0382±0.0032
0.0833±0.0038
0.0743±0.0026
0.0768±0.0024
0.0588±0.0021
0.0966±0.0040
0.0896±0.0035
0.0899±0.0027
0.0597±0.0023
0.0567±0.0031
0.0538±0.0027
0.0564±0.0029
0.0533±0.0017
0.0584±0.0031
0.0581±0.0260
0.0585±0.0021
0.0568±0.0025
0.0964±0.0027
0.0925±0.0033
0.0945±0.0026
0.0633±0.0016
67.42
72.21
70.12
76.42
48.61
54.12
52.58
63.70
40.40
46.68
44.51
63.15
65.00
66.80
65.21
67.12
63.98
64.12
63.92
64.92
40.52
42.91
41.68
60.90
6g
6h
6i
6j
6k
6l
6m
6n
6o
6p
6q
6r
6s
6t
7a
7b
7c
7d
7e
10
10
0.0565±0.0020
0.0523±0.0084
0.0508±0.0071
0.0496±0.0056
0.0698±0.0041
0.0624±0.0036
0.0606±0.0029
0.0641±0.0031
0.0578±0.0019
0.0497±0.0023
0.0504±0.0031
0.0472±0.0017
-
65.12
67.70
68.65
69.04
56.90
61.51
62.58
60.42
64.30
69.31
68.92
70.88
-
7f
7g
10
7h
10
7i
7j
10
10
7k
10
7l
10
7m
10
7n
10
7o
10
7p
10
Control
Standard
0.1ml/kg
10
0.0390±0.0026
75.93
Diclofenac Na is used as the standard: N=6 in each group.
CMC- Carboxy methyl cellulose as a suspending agent.
to 3rd and 6th positions respectively presented highest anti-
inflammatory activity (76.42%) better than the standard drug
Diclofenac Sodium. Other five compounds 6a, 6b, 6c, 6n
and 6p showed very significant activity. They contained 2-
Me-, 3-Me-, 4-Me- and 4-Cl-phenoxymethyphenyl group on
C-3 and 2-chloropyridin-3-yl and 3,5-dichlorophenyl groups
at C-6 position. On the other hand, the remaining compounds
exhibited moderate to good inhibition.
The anti-inflammatory activity of [1,2,4]triazolo[3,4-
b][1,3,4] thiadiazines (7a-7p) is in the range of 40.52-70.88
%. Compounds 7e, 7f, 7g, 7h, 7m, 7n, 7o and 7p showed
significant anti-inflammatory activity. However, the remain-
ing triazolothiadiazines possessed moderate to good activity.
It was observed that the triazolothiadiazine derivatives hav-
ing 5-chloro-2-sulfanamido-3-thienyl and 4-nitrophenyl
groups at C-6 position possess high activity.

[1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazoles and [1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazines
Letters in Drug Design & Discovery, 2011, Vol. 8, No. 2 195
EXPERIMENTAL PROTOCOLS
Chemistry
Hz), 7.26 (d, 2H, Ring A-H, J = 8.9 Hz), 7.44 (t, 1H, Ring
B-H, J = 7.5 Hz), 7.63 (t, 1H, Ring B-H, J = 7.5 Hz), 7.77
(d, 1H, Ring B-H, J = 7.2 Hz), 8.18 (d, 1H, Ring B-H, J =
7.2 Hz).
Melting points were determined by the open capillary
method and are uncorrected. The IR spectra (in KBr pellets)
were recorded on a Shimadzu FT-IR 4100 type A spectro-
1
photometer. H-NMR and 13C-NMR spectra were recorded
General Procedure for the Preparation of Ethyl 2-
(Aryloxymethyl) Benzoates (2a-2d)
on a Varian 400 MHz NMR spectrometer/Perkin-Elmer
EM300 MHz spectrometer using TMS as an internal stan-
dard. The FAB mass spectra were recorded on a JEOL SX
102/DA-6000 spectrophotometer / Data system using Ar-
gon/Xenon (6KV,10mA)FAB gas, at 70 eV. Mass spectra
were recorded on LC–MS-Aglilent 1100 series with MSD
(Ion trap) using 0.1% aqueous TFA in acetonitrile system on
C18-BDS column for 10 min duration. Elemental analysis
was carried out using Flash EA 1112 Series, CHNSO Ana-
The above esters were prepared by refluxing 2-
(aryloxymethyl) benzoic acids (1a-d) in excess absolute
ethanol in the presence of few drops of conc. sulfuric acid
as per the general method employed for the esterification
[24]. The resulting esters had been judged to be pure by
TLC.
Ethyl 2-(2-Methyl Phenoxy Methyl)Benzoate (2a)
lyzer (Thermo). The progress of the reaction
by thin layer chromatography (TLC) on pre-coated silica gel
Colourless solid (82 %); mp 54-56° C; IR (KBr, ꢀ cm-1):
was monitored
1
3072 (ArC-H), 2980 (C-H), 1716 (C=O), 1247 (C-O); H-
Solvents and reagents were purchased from the
commercial vendors in the appropriate grade and were used
without purification.
NMR (400 MHz, CDCl3, ꢁ ppm) : 1.39 (t, 3H, -CH3 ester, J =
7.2 Hz), 2.36 (s, 3H, Ring A-CH3), 4.36 (q, 2H, -CH2 ester, J
= 7.2 Hz), 5.51 (s, 2H, -OCH2), 6.80-6.87 (m, 3H, Ring A-
H), 7.17 (t, 1H, Ring A-H, J = 7.8 Hz), 7.39 (d, 1H, Ring B-
H, J = 8.7 Hz), 7.58 (d, 1H, Ring B-H, J = 7.8 Hz), 7.81 (t,
1H, Ring B-H, J = 7.5 Hz), 8.06 (t, 1H, Ring B-H, J = 7.5
Hz).
G plates.
General Procedure for the Preparation of 2-
(Aryloxymethyl) Benzoic Acid [23] (1a-1d)
Phthalide (15.0g, 112 mmol), substituted phenols (23.6g,
214 mmol) and sodium methoxide (47.6g, 220 mmol) were
suspended in 150 mL of n-butanol and stirred at 140° C for
15 h. The reaction mixture was cooled, 400 ml of water were
added, and the mixture was acidified to pH-4 at 20° C with
concentrated hydrochloric acid. The product obtained was
filtered washed with water and dried. The crude product was
recrystallized from methanol / water.
Ethyl 2-(3-Methyl Phenoxy Methyl)Benzoate (2b)
Colourless solid (85 %); mp 68-70° C; IR (KBr, ꢀ cm-1):
3082 (ArC-H), 2972 (C-H), 1715 (C=O), 1264 (C-O); H-
1
NMR (300 MHz, CDCl ꢁ ppm) : 1.42 (t, 3H, -CH ester, J
3,
3
= 7.2 Hz ), 2.42 (s, 3H, Ring A-CH3), 4.42 (q, 2H, -CH
2
ester, J=7.2 Hz), 5.58 (s, 2H, - OCH ), 6.86-7.17 (m, 4H,
2
Ring A-H), 7.23-7.52 (m, 2H, Ring B-H), 7.67 (d, 1H, Ring
B-H, J = 7.8 Hz), 7.90 (d, 1H, Ring B-H).
2-(2-Methyl Phenoxy Methyl)Benzoic Acid (1a)
Ethyl 2-(4-Methyl Phenoxy Methyl)Benzoate (2c)
Colourless solid (87 %); mp 52-54° C; IR (KBr, ꢀ cm-1):
3094 (ArC-H), 2975 (C-H), 1712 (C=O), 1231 (C-O); H-
Colourless solid (75 %); mp 150-152° C; IR (KBr, ꢀ
cm-1): 3450 (O-H), 3056 (ArC-H), 2941 (C-H), 1694 (C=O),
1
1
1245 (C-O); H-NMR (400 MHz, CDCl ꢁ ppm) : 2.21 (s,
3,
NMR (300 MHz, CDCl ꢁ ppm) : 1.32 (t, 3H, -CH ester, J
3H, Ring A-CH3), 5.46 (s, 2H, - OCH ), 6.71-6.79 (m, 3H,
3,
3
2
= 7.2 Hz), 2.32 (s, 3H, Ring A-CH ), 4.46 (q, 2H, -CH
Ring A-H), 7.107 (t, 1H, Ring A-H), 7.30 (d, 1H, Ring B-
H, J = 8.8 Hz),7.48 (d, 1H, Ring B-H, J = 8.9 Hz), 7.86 (t,
1H, Ring B-H, J = 8.9 Hz), 8.12 (t, 1H, Ring B-H, J = 8.9
Hz).
3
2
ester, J = 7.2 Hz), 5.56 (s, 2H, - OCH ), 6.74 (d, 2H, Ring
2
A-H, J = 7.5 Hz), 7.05-7.12 (d, 2H, Ring A-H, J = 7.5 Hz),
7.39 (d, 1H, Ring B-H, J = 8.7 Hz), 7.49 (d, 1H, Ring B-H,
J = 7.8 Hz), 7.78 (t, 1H, Ring B-H, J= 7.5 Hz), 8.12-8.18 (t,
1H, Ring B-H, J = 7.5 Hz).
2-(3-Methyl Phenoxy Methyl)Benzoic Acid (1b)
Colourless solid (74 %); mp 146-148° C; IR (KBr, ꢀ cm-
1): 3445 (O-H), 3058 (ArC-H), 2992 (C-H), 1689 (C=O),
1255 (C-O).
Ethyl 2-(4-Chloro Phenoxy Methyl)Benzoate (2d)
Colourless solid (89 %); mp 60-62° C; IR (KBr, ꢀ cm-1):
3092 (ArC-H), 3004 (C-H), 1708 (C=O), 1284 (C-O), 748
2-(4-Methyl Phenoxy Methyl)Benzoic Acid (1c)
1
(C-Cl); H-NMR (300 MHz, CDCl ꢁ ppm) : 1.42 (t, 3H, -
3,
Colourless solid (78 %); mp 126-128° C; IR (KBr, ꢀ cm-
CH ester, J = 7.2 Hz ), 4.52 (q, 2H, -CH ester, J = 7.2
Hz), 5.62 (s, 2H, -OCH ), 6.67 (d, 2H, Ring A-H, J = 8.9
3
2
1): 3455 (O-H), 3078 (ArC-H), 2970 (C-H), 1685 (C=O),
2
1
1256 (C-O); H-NMR (300 MHz, CDCl ꢁ ppm) : 2.38 (s,
Hz), 7.16 (d, 2H, Ring A-H, J = 8.9 Hz ), 7.33-7.62 (m, 2H,
Ring B-H), 7.72 (d, 1H, Ring B-H, J = 7.8 Hz), 7.92 (d, 1H,
Ring B-H, J = 7.8 Hz).
3,
3H, Ring A-CH3), 5.36 (s, 2H, - OCH ), 6.75 (d, 2H, Ring
A-H, J = 8.3 Hz), 6.85 (d, 2H, Ring A-H, J = 8.3 Hz), 7.07-
2
7.50 (m, 2H, Ring B-H), 7.65- 8.18 (m, 2H, Ring B-H).
2-(4-chloro phenoxy methyl)benzoic acid (1d)
General Procedure for the Preparation of 2-
(Aryloxymethyl) Benzoyl Hydrazide [20] (3a-3d)
Colourless solid (80 %); mp 167-169° C; IR (KBr, ꢀ cm-
1): 3440 (O-H), 3096 (ArC-H), 2988 (C-H), 1694 (C=O),
Ethyl 2-(aryloxymethyl)benzoates (2a-d) (0.1 mol), hy-
drazine hydrate (0.15 mol) and 20 mL of n-propanol were
refluxed on an oil bath for 10 h. The excess solvent was
1
1236 (C-O), 748 (C-Cl); H-NMR (300 MHz, CDCl
ꢁ
3,
ppm) : 5.53 (s, 2H, -OCH ), 6.93 (d, 2H, Ring A-H, J = 8.9
2

196 Letters in Drug Design & Discovery, 2011, Vol. 8, No. 2
Naveena et al.
then distilled off under reduced pressure and the concen-
trated solution was quenched to ice cold water. The solid
separated was filtered, washed and dried. The crude product
was purified by recrystallization from ethanol.
(C=N); 1H-NMR (400 MHz, CDCl3, ꢀ ppm): 2.16 (s, 3H, Ar-
CH ), 4.70 (s, 2H, NH2), 5.25 (s, 2H, OCH2), 6.76 (d, 1H,
3
Ring A-H, J = 8.1 Hz), 6.86 (t, 1H, Ring A-H, J = 7.4 Hz),
7.07-7.13 (m, 2H, Ring A-H), 7.48 (t, 1H, Ring B-H, J = 7.2
Hz), 7.57-7.61 (m, 2H, Ring B-H), 7.72 (d, 1H, Ring B-H, J
= 8.2 Hz), 11.18 (s, 1H, SH); Anal. calculated for
C16H16N4OS: C, 61.52; H, 5.16; N, 17.93; found: C, 61.48;
H, 5.12; N, 17.82.
2-(2-Methyl Phenoxy Methyl) Benzoyl Hydrazide (3a)
Colourless solid (89 %); mp 118-120° C; IR (KBr, ꢀ
cm-1): 3286 (NH /NH), 3012 (ArC-H), 1644 (C=O), 1252
2
1
(C-O) ; H-NMR (300 MHz, CDCl ꢀ ppm) : 2.30 (s, 3H,
3,
4-Amino-5-[2-(3-Methyl Phenoxy Methyl)]-4H-[1,2,4]-
Triazole-3-Thiol (5b)
Ring A-CH ), 4.18 (s, 2H, -NH ), 5.31 (s, 2H, -OCH ),
6.93 (m, 3H, Ring A-H), 6.36 (t, 1H, Ring A-H, J = 7.8 Hz),
3
2
2
7.48-7.56 (m, 4H, Ring B-H), 7.48 (br.s, 1H, NH).
Colourless solid (72 %); mp 160-162° C; IR (KBr, ꢀ
cm-1): 3314, 3228 (NH2), 3032 (ArC-H), 2548 (SH), 1621
(C=N); Anal. calculated for C16H16N4OS: C, 61.52; H, 5.16;
N, 17.93; found: C, 61.50; H, 5.10; N, 17.78.
2-(3-Methyl Phenoxy Methyl) Benzoyl Hydrazide (3b)
Colourless solid (92 %); mp 108-110° C; IR (KBr, ꢀ
cm-1): 3292 (NH /NH), 3016 (ArC-H), 1638 (C=O), 1256
2
4-Amino-5-[2-(4-Methyl Phenoxy Methyl)]-4H-[1,2,4]-
Triazole-3-Thiol (5c)
1
(C-O); H-NMR (300 MHz, CDCl ꢀ ppm) : 2.36 (s, 3H,
3,
Ar-CH ), 4.16 (s, 2H, -NH ), 5.26 (s, 2H, -OCH ), 6.76-
3
2
2
6.80 (m, 4H, Ring A-H), 7.48-7.52 (m, 4H, Ring B-H), 7.48
(br.s, 1H, NH).
Colourless solid (70 %); mp 124-126° C; IR (KBr, ꢀ
cm-1): 3310, 3240 (NH2), 3027 (ArC-H), 2550 (SH), 1614
(C=N); Anal. calculated for C16H16N4OS: C, 61.52; H, 5.16;
N, 17.93; found: C, 61.42; H, 5.15; N, 17.90.
2-(4-Methyl Phenoxy Methyl) Benzoyl Hydrazide (3c)
Colourless solid (90 %); mp 112-114° C; IR (KBr, ꢀ
4-Amino-5-[2-(4-Chloro Phenoxy Methyl)]-4H-[1,2,4]-
Triazole-3-Thiol (5d)
cm-1): 3288 (NH /NH), 3020 (ArC-H), 1646 (C=O), 1250
2
1
(C-O); H-NMR (300 MHz, CDCl ꢀ ppm) : 2.12 (s, 3H,
3,
Ar-CH ), 4.11 (s, 2H, -NH ), 5.34 (s, 2H, -OCH ), 6.35 (d,
Colourless solid (75 %); mp 168-170° C; IR (KBr, ꢀ
3
2
2
2H, Ring A-H, J = 7.2 Hz), 6.92 (d, 2H, Ring A-H, J = 7.2
cm-1): 3314, 3250 (NH2), 3038 (ArC-H), 2554 (SH), 1611
1
Hz), 7.48-7.58 (m, 4H, Ring B-H), 7.55 (br.s, 1H, NH).
(C=N), 748 (C-Cl); H-NMR (300 MHz, CDCl3, ꢀ ppm):
4.48 (s, 2H, NH2), 5.16 (s, 2H, OCH2), 6.85 (d, 2H, Ring A-
H, J = 7.8 Hz), 7.24 (d, 2H, Ring A-H, J = 7.8 Hz), 7.45 (d,
1H, Ring B-H, J = 7.8 Hz), 7.62 (t, 1H, Ring B-H, J = 7.1
Hz), 7.84 (t, 1H, Ring B-H, J = 7.1 Hz), 8.04 (d, 1H, Ring B-
H, J = 7.8 Hz), 11.17 (s, 1H, SH); Anal calculated for
C15H13ClN4OS: C, 54.13; H, 3.94; N, 16.83; found: C, 54.05;
H, 4.10; N, 16.92.
2-(4-Chloro Phenoxy Methyl) Benzoyl Hydrazide (3d)
Colourless solid (92 %); mp 122-125° C; IR (KBr, ꢀ
cm-1): 3291 (NH /NH), 3014 (ArC-H), 1638 (C=O), 1256
2
1
(C-O), 746 (C-Cl); H-NMR (400 MHz, CDCl3, ꢀ ppm) :
4.07 (s, 2H, -NH2), 5.22 (s, 2H, -OCH2), 6.92 (d, 2H, Ring
A-H, J = 7.2 Hz), 6.25 (d, 2H, Ring A-H, J = 7.2 Hz), 7.59-
7.48 (m, 4H, Ring B-H), 7.40 (br.s, 1H, NH).
General Procedure for the Preparation of 2-Aryl-6-
(2-{Aryloxymethl}Phenyl-[1,2,4]-Triazolo[3,4-b]-[1,3,4]-
Thiadiazoles (6a-6t)
Procedure for the Preparation of 4-Amino-5-[2-
(Aryloxymethyl)]-4H-[1,2,4]-Triazole-3-Thiol (5a-5d)
2-(Aryloxymethyl)benzoic acid hydrazide (3a-3d)
(0.0835 mol) was treated with a solution of potassium hy-
droxide (0.125 mol) in methanol (50 mL) at 0-50 C under
stirring. Then carbon disulfide (0.125 mol) was added slowly
and the reaction mixture was stirred over night at room tem-
perature. The separated product, potassium dithiocarbazate
(4a-4d), was filtered, washed with chilled methanol and fi-
nally dried. It was directly used for next step without purifi-
cation.
A mixture of 4-amino-5-[2-(aryloxymethyl)]-4H-[1,2,4]-
triazole-3-thiol (5a-d) (1 mmol) and (un)substituted benzoic
acid (1.1mmol) in phosphorous oxychloride (5 ml) was re-
fluxed for 6-7 h. The reaction mixture was slowly quenched
into crushed ice with stirring and neutralized with solid so-
dium bicarbonate. The solid separated after standing the
mixture overnight was filtered, washed with cold water,
dried and recrystallized from appropriate solvent to afford
the title compounds. Characterization data of compounds
(6a-t) are summarized in Table 1.
The above potassium dithiocarbazate was treated with a
mixture of water (8 mL) and hydrazine hydrate (2 mmol) and
was refluxed for 11-12 h. The reaction mixture turned to
green with evolution of hydrogen sulfide and finally it be-
came homogeneous. It was then diluted with little cold water
and acidified with concentrated hydrochloric acid. The white
precipitate formed was filtered, washed with cold water and
recrystallized from aqueous ethanol.
2-(2-Chloropyridin-3-yl)-6-{2-[(2-Methylphenoxy)Me-
thyl]Phenyl}-[1,2,4]Triazolo[5,1-b] [1,3,4]Thiadiazole (6a)
IR (KBr, ꢀ cm-1): 3038 (aromatic C-H), 1616 (C=N),
1071 (C-S), 890 (C-Cl); 1H-NMR (400 MHz, CDCl3, ꢀ
ppm): 2.31 (3H, s, Ring A-CH3), 5.69 (s, 2H, O-CH2), 6.85
(t, 1H, Ring A-H, J = 7.3 Hz), 6.94 (d, 1H, Ring A-H, J =
8.6 Hz), 7.12-7.76 (m, 2H, Ring A-H), 7.46 (t, 1H, Ring C-
H, J = 7.5 Hz), 7.57 (d, 2H, Ring C-H, J = 7.8 Hz), 7.86 (d,
1H, Ring B-H, J = 7.8 Hz), 8.30 (d, 1H, Ring B-H, J = 7.6
Hz), 8.91-8.94 (2H, m, Ring B-H); 13C-NMR (100 MHz,
CDCl3, ꢀ ppm): 29.7 (RingA-CH3), 68.4 (OCH2), 111.7 (C6
4-Amino-5-[2-(2-Methyl Phenoxy Methyl)]-4H-[1,2,4]-
Triazole-3-Thiol (5a)
Colourless solid (78 %); mp 146-148° C; IR (KBr, ꢀ
cm-1): 3308, 3244 (NH2), 3030 (ArC-H), 2557 (SH), 1617

[1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazoles and [1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazines
Letters in Drug Design & Discovery, 2011, Vol. 8, No. 2 197
of Ring A), 119.9 (C2 of Ring A) ,120.5 (C4 of Ring C),
122.7 (C3 of Ring A), 125.8 (C2 of Ring C), 126.9 (C3 of
Ring B), 127.3 / 127.4 (C4 / C5 of Ring B), 130.3 (C2 of Ring
B) , 130.6 (C5 of Ring A), 131.0 (C5 of Ring C), 138.1 (C1 &
C6 of Ring B), 139.9 (C4 of Ring A), 151.7 / 154.6 (C3 / C6 of
Ring C), 154.8 (C3 of triazole), 155.4 (C5 of triazole), 156.8
(C1 of Ring A), 164.5 (C7 of thiadiazole). DEPT: 29.7 (CH3),
68.38 (CH2), 111.7, 120.5, 122.7, 126.9, 127.3, 127.4, 130.3,
130.6, 131.0, 139.9, 154.6; LCMS: m / z 434 (M+ , 100%).
C-[CH3]2), 5.59 (s,2H, OCH2), 6.71 (s, 1H, Ring C-H), 6.75
(s, 1H, Ring C-H), 6.94 (s, 1H, Ring C-H), 7.16 (d, 2H, Ring
B-H, J = 7.8 Hz), 7.36 (d, 2H, Ring B-H, J = 7.8 Hz), 7.52-
7.56 (m, 2H, Ring A-H), 7.63 (d, 1H, Ring A-H, J = 8.5 Hz),
8.12 (d, 1H, Ring A-H, J = 8.5 Hz); LCMS: m / z 448 (M+
+1, 100%).
2-(3,4,5-Trimethoxylphenyl)-6-{2-[(2-Methylphenoxy)
Methyl]Phenyl}[1,2,4]Triazolo[5,1-b][1,3,4]Thiadiazole (6i)
IR (KBr, ꢀ cm-1): 3047 (ArC-H), 1624 (C=N), 1077 (C-
2-(2-Chloropyridin-3-yl)-6-{2-[(3-Methylphenoxy)Me-
thyl]Phenyl}[1,2,4]Triazolo[5,1-b] [1,3,4]Thiadiazole (6b)
S); LCMS: m / z 488 (M+, 100%).
2-(3,4,5-Trimethoxylphenyl)-6-{2-[(3-Methylphenoxy)
Methyl]Phenyl} [1,2,4] Triazolo [5,1-b][1,3,4]Thiadiazole
(6j)
IR (KBr, ꢀ cm-1): 3042 (aromatic C-H), 1621 (C=N),
1068 (C-S), 887 (C-Cl); 1H-NMR (300 MHz, CDCl3, ꢀ
ppm): 2.36 (3H, s, Ring A-CH3), 5.52 (s, 2H, O-CH2), 6.80-
7.23 (m, 3H, Ring A-H), 7.68 (s, 1H, Ring A-H), 7.74 (t, 1H,
Ring C-H, J = 7.6 Hz), 7.87 (d, 2H, Ring C-H, J = 7.8 Hz),
7.88 (d, 1H, Ring B-H, J = 7.8 Hz), 8.12 (d, 1H, Ring B-H, J
= 7.6 Hz), 8.31-8.34 (2H, m, Ring B-H).
IR (KBr, ꢀ cm-1): 3047 (ArC-H), 1624 (C=N), 1069 (C-
1
S); H-NMR (300 MHz, CDCl3, ꢀ ppm): 2.07 (s, 3H, Ring
A-CH3), 3.76 (s, 3H , Ring C-CH3), 3.78-3.99 (m, 6H, Ring
C-[CH3]2), 5.42 (s, 2H, OCH2 ), 6.66-6.76 (m, 3H, Ring A-
H), 7.14 (t, 1H, Ring A-H, J = 8.1 Hz), 7.21-7.29 (m, 2H,
Ring C-H), 7.63-7.71 (m, 2H, Ring B-H), 7.92 (t, 1H, Ring
B-H, J = 7.8 Hz), 8.09 (t, 1H, Ring B-H, J = 7.8 Hz); LCMS:
m / z 488 (M+, 100%).
2-(2-Chloropyridin-3-yl)-6-{2-[(4-Methylphenoxy)Methyl]
Phenyl}[1,2,4]Triazolo[5,1-b] [1,3,4]Thiadiazole (6c)
IR (KBr, ꢀ cm-1): 3038 (ArC-H), 1622 (C=N), 1075 (C-
S), 892 (C-Cl); LCMS: m/z 434 (M+ 100%).
2-(3,4,5-TRIMETHOXYLPHENYL)-6-{2-[(4-Chloro-
2-(2-Chloropyridin-3-yl)-6-{2-[(4-Chlorophenoxy)Me-
thyl]phenyl}[1,2,4]Triazolo[5,1-b] [1,3,4]Thiadiazole (6d)
phenoxy)Methyl]Phenyl}
Thiadiazole (6l)
[1,2,4]Triazolo[5,1-b][1,3,4]
IR (KBr, ꢀ cm-1): 3044 (ArC-H), 1628 (C=N), 1070 (C-
S), 882 (C-Cl); 1H-NMR (300 MHz, CDCl3, ꢀ ppm): 5.64 (s,
2H, O-CH2), 6.85 (d, 2H, Ring A-H, J = 7.8 Hz), 7.24 (d,
2H, Ring A-H, J = 7.8 Hz), 7.54 (t, 1H, Ring C-H, J = 7.6
Hz), 7.67 (d, 2H, Ring C-H, J = 7.8 Hz), 7.92 (d, 2H, Ring
B-H, J = 7.4 Hz), 8.32 (d, 2H, Ring B-H, J = 7.4 Hz).
IR (KBr, ꢀ cm-1): 3047 (ArC-H), 1624 (C=N), 1074 (C-
S), 887 (C-Cl); 1H-NMR (300 MHz, CDCl3, ꢀ ppm): 3.64 (s,
3H, Ring C-OCH3), 3.68 (s, 3H, Ring C-OCH3), 3.70 (s, 3H,
Ring C-OCH3), 5.51 (s, 2H, OCH2 ), 6.42 (d, 1H, Ring A-H,
J = 8.1 Hz), 6.56 (d, 1H, Ring A-H, J = 8.3 Hz), 7.11-7.19
(m, 2H, Ring C-H), 7.33-7.41 (m, 2H, Ring B-H), 7.68 (t,
1H, Ring B-H, J = 7.8 Hz), 7.96 (t,1H, Ring B-H, J = 7.8
Hz); LCMS: m/z 510 (M+, 100%).
2-(3,5-Dimethylphenyl)-6-{2-[(2-Methylphenoxy)Methyl]
Phenyl}[1,2,4]Triazolo[5,1-b] [1,3,4]Thiadiazole (6e)
2-(3,5-Dichlorophenyl)-6-{2-[(2-Methylphenoxy)Methyl]
Phenyl}[1,2,4]Triazolo[5,1-b] [1,3,4]Thiadiazole (6m)
IR (KBr, ꢀ cm-1): 3042 (ArC-H), 1621 (C=N), 1081 (C-
1
S); H-NMR (400 MHz, CDCl3, ꢀ ppm): 2.13 (3H, s, Ring
A-CH3), 2.27 (s, 6H, Ring C-[CH3]2), 5.59 (s, 2H, OCH2),
6.81 (s, 1H, Ring C-H), 6.85 (s, 1H, Ring C-H), 7.06 (s, 1H,
Ring C-H), 7.25-7.26 (m, 2H, Ring B-H), 7.50-7.57 (m, 2H,
Ring B-H), 7.60-7.62 (m, 2H, Ring A-H), 7.92 (d, 1H, Ring
A-H, J = 8.5 Hz), 8.19 (d, 1H, Ring A-H, J = 8.5 Hz) ;
LCMS: m / z 427 (M+ +1, 100%).
IR (KBr, ꢀ cm-1): 3040 (ArC-H), 1590 (C=N), 1071 (C-
S), 893 (C-Cl); 1H-NMR (300 MHz, CDCl3, ꢀ ppm): 2.27 (s,
3H, Ring A-CH3), 5.52 (2H, s -OCH2), 6.69-6.78 (m, 3H,
Ring C-H), 7.09 (t, 1H, Ring A-H, J = 8.4 Hz), 7.25 (t, 1H,
Ring A-H, J = 8.1 Hz), 7.52-7.62 (m, 2H, Ring A-H), 7.75-
7.78 (m, 2H, Ring B-H), 7.86 (d, 1H, Ring B-H, J = 8.4 Hz),
8.09 (d, 1H, Ring B-H, J = 8.4 Hz); MS FAB+ (m / z): (468,
M++ 1).
2-(3,5-Dimethylphenyl)-6-{2-[(3-Methylphenoxy)Methyl]
Phenyl}[1,2,4]Triazolo[5,1-b] [1,3,4]Thiadiazole (6f)
IR (KBr, ꢀ cm-1): 3062 (ArC-H), 1632 (C=N), 1069 (C-
2-(3,5-Dichlorophenyl)-6-{2-[(3-methylphenoxy)methyl]
phenyl}[1,2,4]triazolo[5,1-b] [1,3,4]thiadiazole (6n)
IR (KBr, ꢀ cm-1): 3044 (ArC-H), 1581 (C=N), 1076 (C-
S), 887 (C-Cl).
1
S); H-NMR (300 MHz, CDCl3, ꢀ ppm): 2.17 (3H, s, Ring
A-CH3), 2.37 (s, 6H, Ring C-[CH3]2), 5.42 (s,2H, OCH2),
6.71-6.75 (m, 2H, Ring B-H), 6.99-7.01 (m, 2H, Ring B-H),
7.56-7.65 (m, 2H, Ring A-H), 7.31 (s, 1H, Ring C-H), 7.75
(m, 1H, Ring C-H), 8.03 (m, 1H, Ring C-H).
2-(3,5-Dichlorophenyl)-6-{2-[(3-Methylphenoxy)Methyl]
Phenyl}[1,2,4]Triazolo[5,1-b] [1,3,4]Thiadiazole (6o)
2-(3,5-Dimethylphenyl)-6-{2-[(4-Methylphenoxy)Methyl]
Phenyl}[1,2,4]Triazolo[5,1-b] [1,3,4]Thiadiazole (6g)
IR (KBr, ꢀ cm-1): 3054 (ArC-H), 1593 (C=N), 1066 (C-
S), 892 (C-Cl); 1H-NMR (300 MHz, CDCl3, ꢀ ppm): 2.24 (s,
3H, Ring A-CH3), 5.56 (2H, s -OCH2), 6.74 (d, 2H, Ring A-
H, J = 8.2 Hz), 7.06 (d, 2H, Ring A-H, J = 8.1 Hz), 7.42-
7.49 (m, 3H, Ring C-H), 7.50-7.61 (m, 2H, Ring B-H), 7.86
(d, 1H, Ring B-H, J = 8.6 Hz), 8.04 (d, 1H, Ring B-H, J =
8.6 Hz); MS FAB+ (m / z): (468,M++ 1).
IR (KBr, ꢀ cm-1): 3072 (ArC-H), 1630 (C=N), 1068 (C-
S); LCMS: m / z 427 (M+ +1, 100%).
2-(3,5-Dimethylphenyl)-6-{2-[(4-Chlorophenoxy)Methyl]
Phenyl}[1,2,4]Triazolo[5,1-b] [1,3,4]Thiadiazole (6h)
IR (KBr, ꢀ cm-1): 3039 (ArC-H), 1618 (C=N), 1071 (C-
1
S); H-NMR (300 MHz, CDCl3, ꢀ ppm): 2.42 (s, 6H, Ring

198 Letters in Drug Design & Discovery, 2011, Vol. 8, No. 2
Naveena et al.
2-(3-Bromophenyl)-6-{2-[(2-Methylphenoxy)Methyl]
6-(3-Carboxamido-4-Hydroxyphenyl)-3-[2-(4-Chloro-
Phenyl}[1,2,4]Triazolo[5,1-b] [1,3,4]Thiadiazole (6q)
phenoxymethyl)Phenyl]-7H-[1,2,4]Triazolo[3,4-b][1,3,4]
Thiadiazine (7d)
IR (KBr, ꢀ cm-1): 3386, 3045 (NH2), 3028 (aromatic C-
H), 1636 (C=N), 1071 (C-S), 892 (C-Cl); H-NMR (300
MHz, CDCl3, ꢀ ppm): 3.91 (2H, s, SCH2), 5.38 (2H, s,
OCH2), 6.75 (t, 1H, Ring C-H, J = 7.3 Hz), 6.91 (d, 1H, Ring
A-H, J = 8.9 Hz), 7.15 (d, 1H, Ring C-H, J = 8.3 Hz), 7.75
(d, 1H, Ring C-H, J = 5.1 Hz), 7.80 (d, 2H, Ring A-H, J =
8.9 Hz), 7.48-7.59 (m, 2H, Ring B-H), 7.61-7.72 (m, 2H,
Ring B-H), 8.05 (s, 2H, Ring C-CONH2 ),12.86 (s, 1H, Ring
C-OH); LCMS: m / z 493 (M+, 100%).
IR (KBr, ꢀ cm-1): 3028 (ArC-H), 1587 (C=N), 1081 (C-
S), 584 (C-Br); 1H-NMR (300 MHz, CDCl3, ꢀ ppm): 2.25 (s,
3H, Ring A-CH3), 5.54 (2H, s -OCH2), 6.72-7.18 (m, 4H,
Ring A-H), 7.36 (d, 1H, Ring B-H, J = 7.2 Hz), 7.77-7.82
(m, 2H, Ring B-H), 7.92 (d, 1H, Ring B-H, J = 7.2 Hz),
7.98-8.05 (m, 2H, Ring C-H), 8.23 (s,1H, Ring C-H), 8.44
(d, 1H, Ring C-H, J = 7.4 Hz); MS FAB+ (m / z): (478, M++
1).
1
2-(3-Bromophenyl)-6-{2-[(3-Methylphenoxy)Methyl]
Phenyl}[1,2,4]Triazolo[5,1-b] [1,3,4] Thiadiazole (6r)
IR (KBr, ꢀ cm-1): 3032 (ArC-H), 1590 (C=N), 1069 (C-
6-(3-(5-Chloro-2-Sulfonamido)Thienyl)-3-[2-(2-Methyl-
phenoxymethyl)Phenyl]-7H-[1,2,4]Triazolo[3,4-b][1,3,4]
Thiadiazine (7g)
S), 577 (C-Br); MS FAB+ (m / z): (478, M++ 1).
2-(3-Bromophenyl)-6-{2-[(4-Chlorophenoxy)Methyl]
Phenyl}[1,2,4]Triazolo[5,1-b][1,3,4] Thiadiazole (6t)
IR (KBr, ꢀ cm-1): 3395, 3054 (NH2), 3030 (ArC-H), 1631
1
(C=N), 1070 (C-S); H-NMR (300 MHz, CDCl3, ꢀ ppm):
IR (KBr, ꢀ cm-1): 3046 (ArC-H), 1628 (C=N), 1072 (C-
S), 890 (C-Cl); 1H-NMR (300 MHz, CDCl3, ꢀ ppm): 5.57 (s,
2H, OCH2 ), 6.88 (d, 2H, Ring A-H, J = 8.4 Hz), 7.18 (d, 2H,
Ring A-H, J = 8.3 Hz), 7.42 (d, 1H, Ring B-H, J = 7.2 Hz),
7.54-7.62 (m, H, Ring B-H), 7.75 (d, 1H, Ring B-H, J = 7.2
Hz), 7.80-7.85 (m, 2H, Ring C-H), 8.07 (s, 1H, Ring C-H ),
8.18 (d, 1H, Ring C-H, J = 7.6 Hz); LCMS: m / z 498 (M+,
100%).
2.23 (s, 3H, Ring A-CH3), 3.68 (s, 2H, SCH2), 4.82 (s, 2H,
SO2NH2), 5.02 (s, 2H, -OCH2), 6.57 (d, 2H, Ring A-H, J =
8.6 Hz), 6.94 (d, 2H, Ring A-H, J = 8.6 Hz), 6.98 (s, 1H,
Ring C-H), 7.48-7.64 (m, 4H, Ring B-H); 13C-NMR (100
MHz, CDCl3, ꢀ ppm): 20.4 (Ring A-CH3), 25.3 (SCH2), 67.6
(OCH2), 114.2 (C2 & C6 of Ring A), 124.3 (C3 of Ring C),
127.7 (C2 of Ring B), 128.8 (C5 of Ring B), 129.9 & 129.5
(C4 & C3 of Ring B), 130.5 (C4 of Ring A), 131.5 (C4 of
Ring C), 131.5 (C3 & C5 of Ring A), 133.6 (C1 of Ring B),
135.6 (C5 of Ring C), 137.3 (C6 of Ring B), 141.3 (C5 of tria-
zole),142.6 (C3 of triazole), 148.1 (C2 of Ring C), 152.6 (C1
of Ring A), 155.9 (C7 of thiadiazine). LCMS: m / z 533
(M++1, 100%).
General Procedure for the Preparation of 6-aryl-3-({2-
Aryloxymethyl}Phenyl)-7H-1,2,4-Triazolo[3,4-b][1,3,4]
Thiadiazines (7a-7p)
A
mixture 4-amino-5-({2-aryloxymethyl}phenyl)-4H-
1,2,4-triazole-3-thiol (5a-c) (1 mmol) and substituted phena-
cyl bromide (1.2 mmol) in 10 mL of absolute ethanol was
refluxed for 3-4 h. The reaction mixture was slowly
quenched onto crushed ice with stirring and neutralized with
solid sodium bicarbonate. The solid separated after standing
overnight was filtered, washed with cold water, dried and
recrystallised from absolute ethanol to afford the title com-
pounds.
6-(3-(5-Chloro-2-Sulfonamido)Thienyl)-3-[2-(4-Chloro-
phenoxymethyl)Phenyl]-7H-[1,2,4]Triazolo[3,4-b][1,3,4]
Thiadiazine (7h)
IR (KBr, ꢀ cm-1): 3390, 3049 (NH2), 3033 (ArC-H), 1626
(C=N), 1065 (C-S), 894 (C-Cl); 1H-NMR (400 MHz, CDCl3,
ꢀ ppm): 3.60 (s, 2H, SCH2), 4.75 (s, 2H, SO2NH2), 5.22 (s,
2H, -OCH2), 6.42 (d, 2H, Ring A-H, J = 8.4 Hz), 6.84 (d,
2H, Ring A-H, J = 8.4 Hz), 6.78 (s, 1H, Ring C-H), 7.48-
7.52 (m, 2H, Ring B-H), 7.56-7.68 (m, 2H, Ring B-H);
LCMS: m / z 553 (M+, 100%).
6-(3-Carboxamido-4-Hydroxyphenyl)-3-[2-(2-Methyl-
phenoxymethyl)-Phenyl]-7H-[1,2,4]Triazolo[3,4-b][1,3,4]
Thiadiazine (7a)
IR (KBr, ꢀ cm-1): 3380, 3046 (NH2), 3024 (ArC-H), 1632
6-(3-Bromophenyl)-3-[2-(2-Methylphenoxymethyl)
Phenyl]-7H-[1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazine (7i)
1
(C=N), 1064 (C-S); H-NMR (300 MHz, CDCl3, ꢀ ppm):
IR (KBr, ꢀ cm-1): 3048 (ArC-H), 1587 (C=N), 1062 (C-
2.12 (s, 3H, Ring A-CH3), 3.88 (2H, s, SCH2), 5.30 (2H, s,
OCH2), 6.73 (d, 1H, Ring A-H, J = 8.1 Hz), 6.81 (t, 1H,
Ring A-H, J = 7.3 Hz), 6.97-7.04 (m, 2H, Ring A-H), 6.64
(br.s, 1H, Ring C-H), 7.09 (d, 1H, Ring C-H, J = 8.1 Hz),
7.92-7.95 (m, 1H, Ring C-H), 7.48 (t, 1H, Ring B-H, J = 7.3
Hz), 7.56 (t, 1H, Ring B-H, J = 7.3 Hz), 7.69 (d, 1H, Ring B-
H, J = 7.8 Hz), 7.76 (d, 1H, Ring B-H, J = 7.8 Hz), 8.28
(Br.s, 2H, Ring C-CONH2 ), 13.46 (1 H, s, Ring C-OH);
LCMS: m / z 471 (M+, 100%).
S), 585 (C-Br); LCMS: m / z 492 (M+, 100%).
6-(3-Bromophenyl)-3-[2-(4-Methylphenoxymethyl) Phen-
yl]-7H-[1,2,4]Triazolo[3,4-b] [1,3,4] Thiadiazine (7k)
IR (KBr, ꢀ cm-1): 3045 (ArC-H), 1594 (C=N), 1065 (C-
1
S), 575 (C-Br); H-NMR (300 MHz, CDCl3, ꢀ ppm): 2.24
(3H, s, Ring A-CH3), 4.01 (s, 2H, SCH2), 5.23 (s, 2H,
OCH2), 6.43 (d, 2H, Ring A-H, J = 8.6 Hz), 7.01 (d, 2H,
Ring A-H, J = 8.4 Hz), 7.37 (d, 1H, Ring C-H, J = 7.8 Hz),
7.52 (t, 1H, Ring C-H, J = 7.1 Hz), 7.61-7.65 (m, 2H, Ring
C-H), 7.67-7.69 (m, 2H, Ring B-H), 7.75 (d, 1H, Ring B-H,
J = 8.2 Hz), 7.82 (d, 1H, Ring B-H, J = 8.3 Hz); LCMS: m /
z 492 (M+, 100%).
6-(3-Carboxamido-4-hydroxyphenyl)-3-[2-(3-methyl-
phenoxymethyl)
thiadiazine (7b)
phenyl]-7H-[1,2,4]triazolo[3,4-b][1,3,4]
IR (KBr, ꢀ cm-1): 3382, 3036 (NH2), 3026 (ArC-H), 1634
(C=N), 1072 (C-S).

[1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazoles and [1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazines
Letters in Drug Design & Discovery, 2011, Vol. 8, No. 2 199
6-(3-Bromophenyl)-3-[2-(4-Chlorophenoxymethyl) Phen-
yl]-7H-[1,2,4]Triazolo[3,4-b] [1,3,4] Thiadiazine (7l)
dry for 5 minutes. The 10 μg / disc of each of all the test
samples were loaded on 6 mm sterile discs. The loaded disc
was placed on the surface of the corresponding medium the
compound was allowed to diffuse for 5 minutes and the
plates were kept for incubation at 37° C for 24 h. At the end
of incubation, inhibition zones formed around the disc were
measured with transparent ruler in millimeter. These studies
were performed in triplicate. Standard antibacterial drug
ciprofloxacin (10μg / disc) and antifungal drug fluconazole
(10μg / disc) were also tested under similar conditions
against these organisms.
IR (KBr, ꢀ cm-1): 3042 (ArC-H), 1588 (C=N), 1068 (C-
1
S) , 884 (C-Cl), 584 (C-Br); H-NMR (300 MHz, CDCl3, ꢀ
ppm): 2.27 (3H, s, Ring A-CH3), 4.23 (s, 2H, SCH2), 5.38 (s,
2H, OCH2), 6.54 (d, 2H, Ring A-H, J = 8.2 Hz), 7.12 (d, 2H,
Ring A-H, J = 8.2 Hz), 7.41 (d, 1H, Ring C-H, J = 8.2 Hz),
7.65 (t, 1H, Ring C-H, J = 7.1 Hz), 7.82-7.88 (m, 2H, Ring
C-H), 7.97-8.02 (m, 2H, Ring B-H), 8.16 (d, 1H, Ring B-H,
J = 8.4 Hz), 8.28 (d, 1H, Ring B-H, J = 8.4 Hz); LCMS: m /
z 512 (M+, 100%).
3-{2-[(2-Methylphenoxy)Methyl]Phenyl}-6-(4-Nitro-
phenyl)-7H-[1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazine(7m)
Anti-Inflammatory Activity
IR (KBr, ꢀ cm-1): 3041 (ArC-H), 1596 (C=N), 1070 (C-
The anti-inflammatory activity of sixteen newly synthe-
sized compounds was determined by carrageenan induced
paw oedema method [22]. Wistar albino rats of either sex
weighing 180-250g were used for the experiment. They were
housed in the clean polypropylene cages and kept under
room temperature (25o C), relative humidity (60-70 %) in 12
h of light-dark cycle. The animals were given standard labo-
ratory diet and water ad libitum. Food was withdrawn 12 h
before and during experimental hours.
1
S); H-NMR (300 MHz, CDCl3, ꢀ ppm): 2.34 (3H, s, Ring
A-CH3), 3.84 (s, 2H, SCH2), 5.27 (s, 2H, OCH2), 6.42-6.57
(m, 3H, Ring A-H), 6.58-6.61 (m, 1H, Ring A-H), 7.12 (t,
2H, Ring B-H, J = 7.3 Hz), 7.22-7.34 (m, 2H, Ring B-H),
8.05 (d, 2H, Ring C-H, J = 8.2 Hz), 8.21 (d, 2H, Ring C-H, J
= 8.2 Hz); LCMS: m / z 457 (M+, 100%).
3-{2-[(3-Methylphenoxy)Methyl]Phenyl}-6-(4-Nitro-
phenyl)-7H-[1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazine (7n)
The animals were divided into 38 groups with each group
containing 6 animals. A mark was made on the hind paw
(left) just below the tibia-tarsal junction, so that every time
the paw was dipped in the mercury column up to fixed mark
to ensure constant paw volume. The initial paw volume of
each rat was noted by plethysmometrically. First group re-
ceived 0.6% Na CMC and the second group received Di-
clofenac Sodium at a dose of 10mg / kg body weight intra-
muscularly. The 3rd to 38th groups were administered with
the test compounds at a dose 10mg / kg (suspended in 0.6%
CNC given p.o). Thirty minutes after the treatment of test
compounds, 0.1 mL of 1% (w / v) carrageenan was injected
in the sub plantar region of the left hind paw. The right paw
served as a reference to non-inflamed paw for comparison.
The initial paw volume was measured within 30 seconds of
the injection. The relative increase in paw volume was
measured in control, standard and test compounds at 3 h af-
ter the carregeenan injection. The difference between the two
readings was taken as the volume of oedema, the percentage
inhibition by the drugs was calculated using the formula,
IR (KBr, ꢀ cm-1): 3052 (ArC-H), 1586 (C=N), 1067 (C-
S) ; LCMS: m / z 457 (M+, 100%).
3-{2-[(4-Chlorophenoxy)Methyl]Phenyl}-6-(4-Nitro-
phenyl)-7H-[1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazine(7p)
IR (KBr, ꢀ cm-1): 3048 (ArC-H), 1581 (C=N), 1066 (C-
S) , 887 (C-Cl); 1H-NMR (400 MHz, CDCl3, ꢀ ppm): 3.74 (s,
2H, SCH2), 5.22 (s, 2H, OCH2), 6.62 (d, 2H, Ring A-H, J =
8.2 Hz), 6.98 (d, 2H, Ring A-H, J = 8.2 Hz), 7.32 (t, 2H,
Ring B-H, J = 7.3 Hz), 7.38-7.46 (m, 2H, Ring B-H), 7.82
(d, 2H, Ring C-H, J = 8.4 Hz), 8.18 (d, 2H, Ring C-H, J =
8.4 Hz); LCMS: m / z 479 (M++1, 100%).
PHARMACOLOGY
Antimicrobial Activity (Determination of Zone of
Inhibition)
The newly synthesized compounds (6a-6t) and (7a-7p)
were screened for their antimicrobial activity against a total
of four bacterial and two fungal organisms by disc diffusion
method [21]. Stock cultures were maintained at 4°C on
slopes of nutrient agar. Active cultures for experiments were
prepared by transferring a loopful of cells from the stock
cultures to test tubes of Mueller-Hinton broth (MHB) for
bacteria and Sabouraud dextrose broth (SDB) for fungi that
were incubated without agitation for 24 h at 37° C and 25° C
respectively. The cultures were diluted with fresh Mueller-
Hinton and Sabouraud dextrose broth to achieve optical den-
sities corresponding to 2.0x106 colony forming units (CFU /
mL) for bacteria and 2.0x105 spore / mL for fungal strains.
Percentage of oedema inhibition=100 ꢁ (Vtest / Vcontrol) ꢂ 100,
Where Vcontrol = volume of paw oedema in control group;
Vtest = volume of paw oedema in the test compounds in
treated group.
The results were expressed as % inhibition of oedema
over the untreated control group. The results of anti-
inflammatory studies are given in Table 3.
CONCLUSION
In-vitro antimicrobial activity was screened by using
Mueller Hinton Agar (MHA) obtained from Himedia (Mum-
bai). The MHA plates were prepared by pouring 15 mL of
molten media into sterile petriplates. The plates were al-
lowed to solidify for 5 minutes 0.1 % inoculum suspension
was swabbed uniformly and the inoculum was allowed to
Several 1,2,4-triazolo[3,4-b]-1,3,4-thiadizoles and 1,2,4-
triazolo[3,4-b]-1,3,4-thiadiazines were successfully synthe-
1
sized in 60-70% yields and were characterized by H NMR,
13C NMR, Mass spectrometry and IR studies. All the newly
synthesized compounds were screened for antibacterial and
antifungal properties. The antimicrobial activity study re-

200 Letters in Drug Design & Discovery, 2011, Vol. 8, No. 2
Naveena et al.
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vealed that all the compounds tested showed moderate to
good antibacterial and antifungal activities against patho-
genic strains. Structure and biological activity relationship of
title compounds showed that the presence of 4-chloro phe-
[8]
noxymethylphenyl
trimethoxyphenyl,
and
2-chloropyridin-3-yl,
3,4,5-
[9]
3,5-dichlorophenyl,
2-hydoxy-4-
carboxamidophenyl, 5-chloro-2-sulfonamidophenyl groups
attached to position-2 / 3 and 6 of the thiadiazole and thiadi-
azine rings of the title compounds are responsible for good
antimicrobial activity. The screening data showed that the
newly prepared compounds have shown promising antibacte-
rial and antifungal activities against the screened organ-
isms. The investigation of anti-inflammatory activity re-
vealed that many compounds showed significant anti-
inflammatory properties. Few of them, particularly com-
pounds containing 2-Me-, 3-Me-, 4-Me- and 4-Cl-
phenoxymethylphenyl group on C-3 and 2-chloropyridin-3-
yl and 3,5-dichlorophenyl groups at C-6 position showed
good anti-inflammatory activity which is comparable to that
of the standard. Therefore, it was concluded that there exists
ample scope for further study in this class of compounds.
[10]
[11]
[12]
[13]
[14]
[15]
[16]
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ACKNOWLEDGMENT
We are grateful to the Managing Director, SeQuent Sci-
entific Ltd., New Mangalore. The authors are also thankful
to Head, NMR Research centre IISc, Bangalore for provid-
1
ing H-NMR and 13C-NMR spectral facilities. Thanks are
1
also due to CDRI-Lucknow for providing H NMR and
LCMS / FAB Mass spectral analysis.
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