Synthesis and biological effects of new derivatives of benzotriazole as antimicrobial and antifungal agents

Article abstract of DOI:10.1002/jhet.5570390504

Derivatives of 2-aminothiophene-3-carbonitrile, 2-thioxopyridine-3-carbonitrile, 1,8-naphthyridine-2-one, thieno[2,3-b]pyridine-5-carbonitrile and thieno[2,3-d]pyrimidine incorporating with a 1H-benzotriazole moiety or 1,3,4-thiadiazole derivatives incorporating with a benzotriazol-1-ylmethyl group have been synthesized and tested for antimicrobial and antifungal activities. The structures of the newly synthesized compounds have been established on the basis of their analytical and spectral data.

Full text of DOI:10.1002/jhet.5570390504

Sep-Oct 2002
Synthesis and Biological Effects of New Derivatives of Benzotriazole
as Antimicrobial and Antifungal Agents
877
Fatima Al-Omran* [a], Rafat M. Mohareb [b] and Adel Abou El-Khair [a]
[a] Chemistry Department, Faculty of Science, Kuwait University, P.O. Box 5969, 13060 Safat, Kuwait
[b] Chemistry Department, University of California, Berkeley, CA 94720
Received December 26, 2001
Derivatives of 2-aminothiophene-3-carbonitrile, 2-thioxopyridine-3-carbonitrile, 1,8-naphthyridine-2-
one, thieno[2,3-b]pyridine-5-carbonitrile and thieno[2,3-d]pyrimidine incorporating with a 1H-benzo-
triazole moiety or 1,3,4-thiadiazole derivatives incorporating with a benzotriazol-1-ylmethyl group have
been synthesized and tested for antimicrobial and antifungal activities. The structures of the newly synthe-
sized compounds have been established on the basis of their analytical and spectral data.
J. Heterocyclic Chem., 39, 877(2002).
Pharmacological studies of the 1H-benzotriazole
ethanol in the presence of elemental sulfur and a catalytic
amount of piperidine to afford the 2-aminothiophene
derivatives 5b-c. The structures of 5b-c were established
on the basis of their elemental analysis and spectral data.
On the other hand, treatment of benzotriazol-1-yl acetone
(1) with phenyl isothiocyanate in ethanol and in the pres-
ence of potassium hydroxide at room temperature gave the
non-isolable intermediate 6. Such an intermediate reacts
with an equimolar amount of malononitrile (2b) to afford
the corresponding thioxopyridine (8) in good yield. The
formation of 8 is assumed to proceed via initial condensa-
tion of 6 with malononitrile (2b) to form the non-isolable
intermediate 7 that readily undergo cyclization to 8. The
structure of the latter product was established on the basis
of its elemental analysis and spectral data. Thus, the ir
spectrum of the reaction product showed an absorption
nucleus have been shown to posses a variety of pharmaco-
logical activities such as anti-inflammatory [1], antimicro-
bial [2-4], anticonvulsant and CNS depressant [5] effects.
Furthermore, several pharmacological studies have also
pointed out the value of 2-aminothiophene [6,7], naph-
thyridine [8], thieno[2,3-d]pyrimidine [9,10], thieno[2,3-
b]pyridine [11] and thiadiazole [12] as biologically active
nuclei. These findings focused on incorporating 2-
aminothiophene-3-carbonitrile, 2-thioxopyridine-3-car-
bonitrile, 4-amino-2-oxo-1,8-naphthyridine-3-carbonitrile,
4-aminothieno[2,3-b]pyridine-5-carbonitrile and
thieno[2,3-d] pyrimidine with 1H-benzotriazole or 1,3,4-
thiadiazole derivatives incorporating with a benzotriazol-
1-ylmethyl group in the hope of obtaining compounds of
potential antimicrobial and antifungal activities.
- 1
1
Thus, treatment of benzotriazol-1-yl acetone (1) with
benzoylacetonitrile (2a) in refluxing ethanol, and in the
presence of a catalytic amount of piperidine gave a product
that could be formulated as 3 or its isomers 4. Spectral data
seemed to be little help in discriminating 3 or 4. However,
the structure 3 was ruled out on the basis of its reaction
with elemental sulfur in refluxing ethanol and in the pres-
ence of a catalytic amount of piperidine the Gewald reac-
tion [7,13] and gave a product identified as the 2-amino-
thiophene derivative 5a. The structure of the latter product
was established on the basis of its elemental analysis and
spectral data. Thus, the ir spectrum of the reaction product
band at 3329 cm due to the two NH groups. The H nmr
spectrum of 8 revealed two broad signals (D O–exchange-
2
able) at d 8.67 and d 12.00 ppm due to the two NH protons
in addition to the methyl protons at 2.29 ppm and aromatic
protons resonating at 6.97-8.16 ppm.
Treatment of compound 1 with dimethylformamide
dimethylacetal (DMF DMA) in dry xylene at reflux
afforded the enaminone 9 [14] in good yield. Treatment of
the latter compound with malononitrile dimer 10 gave the
1,8-naphthyridine-3-carbonitrile derivative 11 [8] in good
yield. The structure of the latter product was established on
the basis of elemental analysis and spectral data. Thus, the
- 1
showed absorption bands at 3352 and 3244 cm corre-
ir spectrum of the reaction product 11 showed absorption
- 1
sponding to NH group in addition to the strong absorption
bands at 3430 - 3330 cm due to NH and NH groups in
2
- 1
2
band at 1661 cm , which can be assigned to the carbonyl
addition to the two strong absorption bands at 2209 and
- 1
absorption. Compound 5a could be obtained in situ, via a
one step process by treatment of 1 with benzoylacetonitrile
(2a) in refluxing ethanol and in the presence of elemental
sulfur and a catalytic amount of piperidine. This affords a
product identical in all respects (mp and spectra) with that
obtained previously from the reaction 4 with elemental
sulfur.
1656 cm , which can be assigned to the nitrile and amide
1
carbonyl absorptions, respectively. The H nmr spectrum
of the product did not show signals for the dimethylamino
group but showed singlets at d 1.97 and d 8.31 ppm for
H
H
the methyl protons and H-7 of the naphthyridine respec-
tively. Also revealed two broad signals (D O exchange-
2
able) at d 8.99 and d 10.06 ppm due to NH and NH
H
H
2
In a similar manner, compound (1) reacted with mal-
ononitrile (2b) or ethyl cyanoacetate (2c) in refluxing
protons and multiplets at d 7.47-8.17 ppm corresponding
to aromatic protons (Scheme 1).
H

878
F. Al-Omran, R. M. Mohareb and A. A. El-Khair
Vol. 39
Scheme 1
Thus, 5b reacted with arylidenemalononitrile 12a,b to
afford thieno[2,3-b]-pyridine derivatives 14a,b. The struc-
ture of 14 was established on the basis of its elemental
1
analysis and spectral data. Thus, the H nmr spectrum
revealed the presence of a methyl singlet at d 1.91 ppm.
The formation of the product is assumed to proceed via
addition of the amino group in 5b to the double bond in 12
followed by cyclization and aromatization by loss of
hydrogen cyanide to give 14 (Scheme 2). Compound 5b
was acylated with acetic acid under reflux to furnish the
corresponding N-acylamino derivative 15. An attempt to
obtain the thieno[2,3-d]pyrimidinone 16 by increasing the
reaction time, failed.
On the other hand, treatment of 5b with dimethylfor-
mamide dimethylacetal (DMF DMA) at reflux tempera-
ture gave directly the amidine derivative 17 in high yield.
Similarly, compound 5b reacted with ethyl cyanoacetate
(2c) to give a single product of molecular formula
C H N OS corresponding to the isomeric structures 18
15 10
6
1
or 20. Structure 18 was ruled out on the basis of the H
nmr spectrum of the reaction product which revealed the
presence of CH - protons as a singlet at d 4.13. Moreover,
2
13
the C nmr spectrum showed a carbon resonating at d
C
165.17, assigned to the carbonyl carbon of structure 20.
The formation of 20 is assumed to take place via an inter-
mediate 19, which cannot be isolated and cyclizes into 20
under the reaction condition (Scheme 2).
Ethyl benzotriazol-1-yl acetate (21) [15] was allowed to
react with hydrazine hydrate in ethanol to give 1H-benzo-
triazolacetic acid hydrazide 22 [2]. Condensation of the
latter compound with benzoyl chloride (23a) or 2-thienoyl
chloride (23b) in refluxing 1,4-diaxan as solvent and in the
presence of ammonium acetate yielded the corresponding
Compound 5b exhibited high reactivity leading to a
wide range of polyfunctionally substituted heterocycles.
The amino group in compound 5b was more nucleophilic
than the methyl group.
Scheme 2

Sep-Oct 2002
New Derivatives of Benzotriazole as Antimicrobial and Antifungal Agents
879
1,3,4-thiadiazole derivatives 24a,b. The structures of
24a,b were established via their elemental analysis and
spectroscopic data. The mass spectrum of 24a revealed a
molecular ion peak at m/z (EI) = 336 (M ). The H nmr
spectrum showed in addition to the aromatic signals, sin-
glet signal at d 6.46 for methylene protons and a signal at d
10.50 was assigned to the NH proton. This signal under-
went a facile hydrogen deuterium exchange upon addition
of deuterium oxide.
The NH group of compound 24a is highly reactive, and
is more nucleophilic than the methylene carbon. Thus, 24a
reacted with ethyl chloroacetate (25a), chloroacetonitrile
(25b) and chloroacetone (25c) in refluxing dimethylfor-
mamide and catalytic amounts of triethylamine to afford
26a-c. Both elemental analysis and spectral data are com-
patible with the assigned structures. The NH band was not
observed, in the ir spectra of compounds 26a-c Moreover,
treatment of compound 24a with a -chloroacetylacetone in
dimethylformamide and few drops of triethylamine at
reflux gave a pale brown product which was identified as
N-(1-Acetyl-2-oxopropyl)-N-(5'-benzotriazol-1-ylmethyl-
[1',3',4']thiadiazol-2-yl)benzamide 27 (Scheme 3).
Treatment of compound 27 with hydrazine hydrate in
refluxing ethanol gave, N-(5-benzotriazol-1-
ylmethyl[1,3,4]thiadiazol-2-yl)-N-(3,5-dimethyl-1H-pyra-
zol-4-yl)-benzamide 28 (Scheme 3).
+
1
Treatment of ethyl 4-chloroacetoacetate 29 with 1-H-
benzotraizole to afford ethyl 4-benzotriazol-1-yl acetoac-
etate 30 which was allowed to react with phenylhydrazine
in refluxing ethanol gave the hydrazone derivative 31. On
the other hand, the reaction of 30 with hydrazine hydrate
under similar conditions afforded the pyrazolone 33 in
good yield. The structure of the isolated products was con-
firmed on the basis of elemental analysis and spectral data.
Treatment of 5-benzotriazol-1-ylmethyl-2,4-dihydropy-
razol-3-one (33) with benzylidinemalononitrile (13a) in
refluxing ethanol afforded the 4H-pyrano[2,3-c]pyrazole-
5-carbonitrile derivative 34 [16,17] in good yield (Scheme
1
4). The H nmr spectrum of compound 34 revealed a sin-
glet at d 4.58 corresponding to the pyran C-H proton and
two doublets at d 5.20 and 5.78 for the methylene protons,
which indicate that they are not equivalent (Scheme 4).
Scheme 3
Scheme 4

880
F. Al-Omran, R. M. Mohareb and A. A. El-Khair
Vol. 39
few drops of piperidine was refluxed for 4 hours and then left to
cool at room temperature. The product, so formed, was collected
by filtration and recrystallized from ethanol as yellow crystals
92% yield, mp 152-154 °C; ir: n 2225 (CN) and 1697 cm- 1 (CO);
1H nmr (dimethyl-d6 sulfoxide): dH 2.13 (s, 3H, Me), 5.70 (s, 2H,
CH2); 7.11-8.13 ppm (m, 9H, Ar-H).
Biological Activity.
The biological activities of some of the newly synthe-
sized compounds were screened for their antifungal activ-
ity against Aspergillus niger and Fusarium oxysporium,
while the antibacterial activity was tested against
Escherchia coli, Bacillus subtilis and Staphylococcus
aureus. Most of the tested sample showed bactericidal and
fungicidal activity (Table 1).
Anal. Calcd. for C18H14N4O: C, 71.51; H, 4.67; N, 18.53.
Found: C, 71.17; H, 4.96; N, 18.52.
2-Amino-5-benzotriazol-1-yl-3-benzoyl-4-methylthiophene
(5a).
Method A.
Table 1
In vitro Bactericidal and Fungicidal Activities
To a solution of 4 (3.34 g, 10 mmol) in ethanol (20 mL) were
added elemental sulfur (0.32 g, 10 mmol) and a few drops of
trimethylamine. The mixture was refluxed for 7 hours and then
left to cool at room temperature. The product, so formed, was
collected by filtration and recrystallized from ethanol/dimethyl-
formamide (2:1).
of Newly Synthesized Compounds
Compound E- coli B-subtilis S-aureus A-niger F-oxysporium
5a
5b
5c
8
11
14
15
17
20
24a
24b
26b
26c
27
-
-
-
-
-
-
-
-
-
++
-
-
+++
-
++++
++++
+
+++
+++
++++
++++
+++++
++++
-
-
-
+++
++++
+++
+++
-
++
++++
++++
+++
++
+++
-
Method B.
A mixture of benzotraizol-1-yl acetone (1.75 g, 10 mmol) ben-
zoylacetonitrile (1.45 g, 10 mmol), elemental sulfur (0.32 g, 10
mmol) in ethanol (20 mL) and a few drops of piperidine was
refluxed for 5 hours and then poured into ice cold water. The
solid product, so formed, was collected by filtration and recrys-
tallized from ethanol/dimethylformamide (2:1) as brown crystals
in 71% yield; mp. 129-131 °C; ir: n 3352, 3244 (NH2) and 1661
cm- 1 (CO); 1H nmr (dimethyl-d6 sulfoxide): dH 1.30 (s, 3H, Me),
7.46-8.16 (m, 9H, Ar-H) and 8.36 ppm (br, 2H, NH2).
-
++++
++
++
+++
+++
+++
++++
+++
--
-
+
++
-
-
-
++
+++
-
++++
++++
-
-
+++
-
-
-
--
-
+
++++
-
+++
-
--
++++
+++++
Anal. Calcd. for C18H14N4OS: C, 64.66; H, 4.22; N, 16.76.
Found: C, 64.85; H, 4.22; N, 17.14.
28
No effect = -; Slight effect = +; Moderate effect = ++; Strong
effect = +++, ++++ & +++++
General Procedure for the Synthesis of 5b,c.
A reaction carried out as described for the preparation of 5a,
by the method B, but with malononitrile (2b) (0.66 g, 10 mmol)
or ethyl cyanoacetate (2c) (1.13 g, 10 mmol) in place of benzoy-
lacetonitrile to give 5b and 5c, respectively.
Acknowledgement.
This work was financed by the University of Kuwait
research grant SC 100. We are grateful to the Faculty of
Science, Chemistry Department, SAF facility for the spec-
tral and analytical data (Project G 01/01 & G 03/01). We
are also grateful to Dr. I. H. Abbas for biological activity
tests.
2-Amino-5-benzotriazol-1-yl-4-methylthiophene-3-carbonitrile
(5b).
This compound was recrystallized from ethanol as deep brown
crystals (81%), mp 190-192 °C; ir, n 3313, 3150 (NH2) and 2209
cm- 1 (CN); 1H nmr (dimethyl-d6 sulfoxide); dH 1.89 (s, 3H, Me),
7.47-8.16 (m, 4H, Ar-H) and 8.18 ppm (br, 2H, NH2); 13C nmr
(dimethyl-d6 sulfoxide): dC 145.64, 135.06, 134.36, 130.25,
128.49, 125.99, 125.12, 120.50, 119.73, 116.25, 111.43 (aromatic
carbons & CN) and 13.06 ppm (Me).
EXPERIMENTAL
All melting points are uncorrected. The ir spectra were
Anal. Calcd. for C12H9N5S: C, 56.47; H, 3.55; N, 27.44.
Found: C, 56.21; H, 3.88; N, 27.38.
1
recorded on a Shimadzu 2000 FTIR spectrometer. H and 13C
nmr spectra were recorded on a Bruker 400 MHz spectrometer
with dimethyl-d6 sulfoxide or deuteriochloroform as solvent and
tetramethylsilane (TMS) as an internal standard; chemical shifts
are reported as d units (ppm). Mass spectra were measured on
GS/MS INCOL XL Finningan MAT. Microanalyses were per-
formed on a Leco-CHNS 932 analyzer. Compounds 1, 9, 21 and
22 were prepared following literature procedure [14], [14], [15]
and [2], respectively.
Ethyl 2-Amino-5-benzotriazol-1-yl-4-methylthiophene-3-car-
boxylate (5c).
This compound was recrystallized from ethanol as pale green
crystals (73%), mp 120-121 °C; ir, n 3407, 3271 (NH2) and 1696
cm- 1 (ester CO); 1H nmr (dimethyl-d6 sulfoxide); dH 1.31 (t, 3H,
J=7Hz, Me), 1.95 (s, 3H, Me), 4.24 (q, 2H, J=7Hz, OCH2), 7.50-
7.78 (m, 4H, Ar-H) and 8.18 ppm (br, 2H, NH 2 D2O-
exchangable); 13C nmr (dimethyl-d6 sulfoxide): dC 165.80 (ester
CO), 145.71, 135.40, 134.39, 130.07, 128.38, 125.81, 125.48,
124.95, 120.51, 111.49 (aromatic carbons) 60.41 (OCH2), 15.15
and 14.61 ppm (2Me).
4-Benzotriazol-1-yl-2-benzoyl-3-methyl-2-butenenitrile (4).
A mixture of benzotriazol-1-yl acetone (1.75 g,10 mmol) and
benzoylacetonitrile (1.45 g, 10 mmol) in ethanol (20 mL) and

Sep-Oct 2002
New Derivatives of Benzotriazole as Antimicrobial and Antifungal Agents
881
Anal. Calcd for C14H14N4O2S: C, 55.62; H, 4.67; N, 18.54.
2-Acetylamino-5-benzotriazol-1-yl-4-methylthiophene-3-car-
bonitrile (15).
Found: C, 55.94; H, 4.59; N, 18.32.
A solution of 5b (2.5 g, 10 mmol) in acetic acid (20 mL) was
refluxed for 3 hours and then left to cool at room temperature.
The reaction mixture was poured into ice-cold water. The solid
product, so formed, was collected by filtration and recrystallized
from a mixture of ethanol/dimethylformamide (2:1) as brown
crystals in 75% yield; mp. 167-169 °C; ir: n 3198 (NH), 2217
(CN) and 1643 cm- 1 (CO); 1H nmr (dimethyl-d6 sulfoxide): dH
1.91 (s, 3H, Me), 2.07 (s, 3H, Me), 7.43-8.31 (m, 4H, Ar-H) and
12.22 ppm (br, 1H, NH, D2O-exchangable); 13C nmr (dimethyl-
d6-sulfoxide): dC 172.87, 148.58, 134.93, 132.37, 130.08,
128.63, 125.80, 124.90, 121.63, 120.72, 114.63, 111.37 (aromatic
carbons & CN), 21.38 and 23.23 ppm (2Me).
6-Anilino-5-benzotriazol-1-yl-1,2-dihydro-4-methyl-2-thioxopy-
ridine-3-carbonitrile (8).
A mixture of 1 (1.75 g, 10 mmol) phenyl isothiocyanate (1.35
g, 10 mmol) and KOH (0.56, 10 mmol) in ethanol (20 mL) was
stirred at room temperature for 3 hours. To the reaction mixture
malononitrile (0.66 g, 10 mmol) was added and stirring was con-
tinued overnight. The product, so formed, was collected by filtra-
tion and recrystallized from ethanol as brown crystals 72% yield,
mp 130-132 °C; ir: n 3329 (2NH) and 2201 cm- 1 (CN); 1H nmr
(dimethyl-d6 sulfoxide): dH 2.29 (s, 3H, Me), 6.97-8.16 (m, 9H,
Ar-H), 8.67 (br, 1H, NH) and 12.00 ppm (br, 1H, NH).
Anal. Calcd. for C19H14N6S: C, 63.68; H, 3.94; N, 23.45.
Found: C, 63.39; H, 4.17; N, 23.21.
Anal. Calcd. for C14H11N5OS: C, 56.56; H, 3.73; N, 23.56.
Found: C, 56.78; H, 3.90; N, 23.81.
4-Amino-6-benzotriazol-1-yl-1,2-dihydro-5-methyl-2-oxo-1,8-
naphthyridine-3-carbonitrile (11).
5-Benzotriazol-1-yl-2-(dimethylaminomethylenimino)-4-
methylthiophene-3-carbonitrile (17).
A mixture of 9 (2.30 g, 10 mmol) and malononitrile dimer (10)
(1.32 g, 10 mmol) was refluxed in sodium ethoxide (prepared from
0.6 g sodium metal and 60 mL ethanol) for 4 hours, then poured into
ice-cold water and neutralized with HCl (10%). The product, so
formed, was collected by filtration and recrystallized from ethanol
as red crystals 75% yield, mp 230-232 °C; ir: n 3430, 3330 (NH and
NH2) 2209 (CN) and 1656 cm- 1 (CO); 1H nmr (dimethyl-d6 sul-
foxide):dH 1.97 (s, 3H, Me), 7.47-8.17 (m, 4H, Ar-H), 8.31 (s, 1H,
H-7), 8.99 (br, 2H, NH2) and 10.06 ppm (br, 1H, NH).
A mixture of 5b (2.5 g, 10 mmol) and dimethylformamide
dimethylacetal (1.33 g, 10 mmol) in 20 mL dimethylformamide
was refluxed for 3 hours. The solvent was evaporated under
reduced pressure and the residue recrystallized from a mixture of
ethanol/dimethylformamide (2:1) as pale green crystals in 85%
yield; mp. 140-142 °C; ir: n 2211 cm- 1 (CN); 1H nmr (dimethyl-
d6 sulfoxide): dH 2.01 (s, 3H, Me), 3.03 (s, 6H, NMe2), 5.87 (s,
1H, methylene CH) and 7.52-8.21 (m, 4H, Ar-H).
Anal. Calcd. for C15H14N6S: C, 58.05; H, 4.55; N, 27.09.
Found: C, 58.46; H, 4.36; N, 26.92.
Anal. Calcd. for C16H11N7O: C, 60.56; H, 3.49; N, 30.90.
Found: C, 60.32; H, 3.64; N, 30.63.
6-Benzotriazol-1-yl-5-methyl-4-oxo-1,4-dihydrothieno[2,3-
d]pyrimidin-2-ylacetonitrile (20).
General Procedure for the Synthesis of Substituted Thieno[2,3-b]-
pyridines 14a,b.
A mixture of compound 5b (2.50 g, 10 mmol) and ethyl cyano-
acetate 2c (1.13 g, 10 mmol) was heated for 15 minutes at 150 °C
in oil bath, then 20 mL of pyridine was added. The reaction mix-
ture was refluxed for 3 hours, then cool and neutralized with 10%
HCl. The solid product, so formed, was collected by filtration and
recrystallized from ethanol/DMF (1:2) as brown crystals in 69%
yield; mp. 202-204 °C, ir: n 3339 (NH), 2213 (CN), 1637 cm- 1
(CO); 1H nmr (dimethyl-d6 sulfoxide); 2.09 (s, 3H, Me), 4.13 (s,
2H, CH2), 7.41-8.15 (m, 4H, Ar-H) and 8.79 (br, 1H, NH); 13C
(dimethyl-d6 sulfoxide): 165.17, 154.01, 149.74, 142.76, 134.42,
133.91, 129.95, 128.64, 126.64, 125.69, 120.64, 118.14 and 116.33
(aromatic carbons & CN), 50.39 (CH2) and 21.84 ppm (Me).
Anal. Calcd. for C15H10N6OS: C, 55.90; H, 3.13; N, 26.08.
Found: C, 55.63; H, 3.44; N, 25.96.
To a suspension of 5b (2.50 g, 10 mmol) in pyridine (20 mL)
was added benzylidinemalononitrile (12a) (1.54g, 10 mmol) or
p-methoxybenzylidinemalononitrile (12b) (1.84 g, 10 mmol).
The mixture was stirred for 8 hours, neutralized with HCl (10%),
then poured into ice-cold water. The solid product, so formed,
was collected by filtration and recrystallized from ethanol.
4-Amino-2-benzotriazol-1-yl-3-methyl-6-phenylthieno[2,3-b]-
pyridine-5-carbonitrile (14a).
This compound was obtained as deep brown crystals in 82%
yield; mp. 160-162 °C; ir: n 3336, 3197 (NH2) and 2208 cm- 1
(CN); 1H nmr (dimethyl-d6 sulfoxide): dH 1.91 (s, 3H, Me), 7.12-
8.39 (m, 9H, Ar-H) and 8.69 ppm (br, 2H, NH2).
Anal. Calcd. for C21H14N6S: C, 65.96; H, 3.69; N, 21.98.
Found: C, 66.03; H, 3.98; N, 22.02.
General Procedure for the Synthesis of 24a,b.
A mixture of benzoyl chloride 23a (1.40 g, 10 mmol) or 2-thio-
phene carbonylchloride 23b (1.07 g, 10 mmol) and ammonium
thiocyanate (0.76 g, 10 mmol) in 20 mL of 1,4-dioxan was heated
under reflux for 20 minutes. To the reaction mixture, compound
22 (1.91 g, 10 mmol) was added. The reaction mixture was
refluxed for 2 hours and then poured into ice-cold water. The
solid product, so formed, was collected by filtration and recrys-
tallized from ethanol.
4-Amino-2-benzotriazol-1-yl-6-p-methoxyphenyl-3-methylth-
ieno[2,3-b]pyridine-5-carbonitrile (14b).
This compound was obtained as deep green crystals in 73%
yield; mp. 106-108 °C; ir: n 3338, 3195 (NH2) and 2210 cm- 1
(CN); 1H nmr (deuteriochloroform): dH 1.90 (s, 3H, Me), 3.82 (s,
3H, OMe); 7.17-8.71 (m, 8H, Ar-H) and 8.78 ppm (br, 2H, NH2);
13C nmr (dimethyl-d6 sulfoxide): dC 164.23, 161.20, 153.79,
149.89, 145.23, 143.08, 135.07, 134.50, 130.18, 128.82, 126.75,
125.35, 124.78, 120.53, 120.06, 118.90, 115.90, 111.23 (aromatic
carbons & CN), 56.70 (OMe) and 21.74 ppm (Me).
N-(5-Benzotriazol-1-ylmethyl-[1,3,4]thiadiazol-2-yl)benzamide
(24a).
This compound was obtained as pale yellow crystals in 78%
yield, mp. 250-252 °C. ir: n 3436 (NH) and 1664 cm- 1 (CO); 1H
Anal. Calcd. for C22H16N6OS: C, 64.07; H, 3.89; N, 20.38.
Found: C, 64.11; H, 4.12; N, 20.28.

882
F. Al-Omran, R. M. Mohareb and A. A. El-Khair
Vol. 39
nmr (dimethyl-d6 sulfoxide); d 6.46 (s, 2H, CH2), 7.49-8.03 (m,
9H, Ar-H) and 10.50 ppm (br, 1H, NH, D2O-exchangable); ms:
(EI), m/z 336 (M)+.
Anal. Calcd. for C16H12N6OS:C, 57.13; H, 3.59; N, 24.98.
Found: C, 57.30; H, 4.35; N, 24.56.
Anal. Calcd. for C19H16N6O2S: C, 58.16; H, 4.11; N, 21.42.
Found: C, 58.20; H, 4.25; N, 21.42.
N-(1-Acetyl-2-oxopropyl)-N-(5'-benzotriazol-1-ylmethyl-
[1',3',4']thiadiazol-2-yl)benzamide (27).
A mixture of compound 24a (3.36 g, 10 mmol),
a -chloroacetylacetone (1.35 g, 10 mmol) in dimethylformamide
(20 mL) and few drops of triethylamine were refluxed for three
hours then allowed to cool. To the reaction mixture 20 mL of
ethanol and water were added. The solid product, so formed, was
collected by filtration and recrystallized from ethanol as pale
brown crystals in 88% yield; mp. 102-104 °C, ir: n 1671 (2CO),
N-(5'-Benzotriazol-1-ylmethyl[1',3',4']thiadiazol-2'-yl)thio-
phene-2-carboxamide (24b).
This compound was obtained as pale yellow crystals in 93%
yield, mp. 277-279 °C, ir: n 3425 (NH) and 1644 cm- 1 (CO); 1H
nmr (dimethyl-d6 sulfoxide); d 6.47 (s, 2H, CH2), 7.24-8.11 (m,
7H, Ar-H) and 8.27 ppm (bs, 1H, NH, D2O-exchangable); ms:
(EI), m/z 336 (M)+.
1
1625 (amide CO); H nmr (dimethyl-d6 sulfoxide): dH 2.07 (s,
Anal. Calcd. for C14H10N6S2O: C, 49.12; H, 2.92; N, 24.56.
Found: C, 49.25; H, 3.07; N, 24.27.
3H, Me), 2.17 (s, 3H, Me), 2.50 (s, 1H, CH), 6.44 (s, 2H, CH2),
7.44-8.13 (m, 9H, Ar-H); 13C nmr (dimethyl-d6 sulfoxide): dC
189.00, 186.97 (2CO), 173.98, 167.30, 161.19, 158.83, 154.53,
145.77, 135.59, 131.81, 129.46, 124.87, 119.88, 118.44, 110.96
(aromatic & other carbon atoms), 46.94 (CH2), 36.64 (CH),
31.62 ppm (2Me); ms: (EI), m/z 434.1 (M+).
General Procedure for the Synthesis of 26a-c.
A mixture of 24a (3.36 g, 10 mmol), ethyl cyanoacetate (25a)
(1.13 g, 10 mmol) or chloroacetonitrile (25b) (0.73 g, 10 mmol)
or chloroacetone (25c) (0.76 g, 10 mmol) in 20 mL of dimethyl-
formamide and few drops of triethylamine was refluxed for 3
hours. The solid product, so formed, was collected by filtration
and recrystallized from the proper solvent.
Anal. Calcd. for C21H18N6O3S: C, 58.06; H, 4.18; N, 19.35.
Found: C, 58.44; H, 4.27; N, 19.48.
N-(5-Benzotriazol-1-ylmethyl[1,3,4]thiadiazol-2-yl)-N-(3,5-
dimethyl-1H-pyrazol-4-yl)-benzamide (28).
Ethyl N-[(5-Benzotriazol-1-ylmethyl[1,3,4]thiadiazol-2-yl)ben-
zoylamino]acetate (26a).
A suspension of compound 27 (3.86 g, 10 mmol) in ethanol
(20 mL) was treated with hydrazine hydrate (0.5 g, 10 mmol).
The reaction mixture was refluxed for 3 hours then allowed to
cool. The solid product, so formed, was collected by filtration
and recrystallized from ethanol as pale brown crystals in 69%
This compound was recrystallized from ethanol as brown crys-
tals (71%), mp 99-101 °C, ir, n 1750 (ester CO); 1671 (amide
CO); 1H nmr (dimethyl-d6 sulfoxide): dH 1.16 (t, 3H, J=7Hz,
Me), 4.16 (q, 2H, J=7Hz, OCH2); 5.30 (s, 2H, CH2), 6.44 (s, 2H,
-CH2) and 7.47-8.16 ppm (m, 9H, Ar-H); 13C nmr (dimethyl-d6
sulfoxide): dC 173.55, 167.07, 166.07, 153.62, 145.74, 135.51,
133.29, 129.97, 128.83, 127.66, 124.96, 119.88, 118.45 and
110.94 (aromatic & other carbon atoms) 61.96 (OCH2), 52.05
(CH2), 46.63 (CH2) and 22.48 ppm (Me).
1
yield; mp 154-156 °C, ir: n 3370 (NH), 1625 (amide CO). H
nmr (dimethyl-d6 sulfoxide): dH 2.04 (s, 3H, Me), 2.07 (s, 3H,
Me), 6.05 (bs, 1H, NH), 6.41 (s, 2H, CH2), 7.45 - 8.12 ppm (m,
9H, Ar-H).
Anal. Calcd. For C21H18N8SO: C, 58.60; H, 4.21; N, 26.03.
Found: C, 58.60; H, 4.52; N, 25.84.
Anal. Calcd for C20H18N6O3S: C, 56.87; H, 4.30; N, 19.90.
Found: C, 56.83; H, 4.50; N, 19.60.
Ethyl 4-Benzotriazol-1-ylacetoacetate (30).
N-(5-Benzotriazol-1-ylmethyl[1,3,4]thiadiazol-2-yl)-N-(1-
cyanomethyl)benzamide (26b).
A mixture of 1-H-benzotriazole (1.19 g, 10 mmol) in toluene
(20 mL) and sodium hydride (0.24 g, 10 mmol) was refluxed for
1 hour then allowed to cool at room temperature. To the mixture,
compound 29 (1.65 g, 10 mmol) was added and the mixture
refluxed for 6 hours. The solvent was evaporated under reduced
pressure and the resulting solid product, so formed, was collected
by filtration and recrystallized from ethanol as pale brown crys-
tals in 67% yield; mp; 120-121 °C, ir: n 1726 and 1743 cm- 1
(2CO); 1H nmr (deuteriochloroform): dH 1.28 (t, 3H, J=7 Hz,
Me), 3.58 (s, 2H, CH2), 4.18 (q, 2H, J=7 Hz, CH2), 5.66 (s, 2H,
CH2) and 7.33-8.05 (m, 4H, Ar-H); 13C nmr (deuteriochloro-
form): dC 200.41 (ketone CO), 172.38 (ester CO), 146.27,
139.10, 128.60, 124.68, 120.34, 118.55 (aromatic carbons), 62.39
(OCH2), 58.63 (CH2), 50.18 (CH2) and 14.43 ppm (Me).
Anal. Calcd. For C12H13N3O3: C, 58.29; H, 5.30; N, 17.00.
Found: C, 58.00; H, 5.35; N, 16.69.
This compound was crystallized from ethanol as pale brown
crystals (69%), mp 140-142 °C; ir, n 2197 (CN) and 1625 cm- 1
(amide CO); 1H nmr (dimethyl-d6 sulfoxide); dH 5.71 (s, 2H,
CH2), 6.45 (s, 2H,CH2), and 7.45-8.28 (m, 9H, Ar-H); 13C nmr
(dimethyl-d6 sulfoxide): dC 174.02, 166.18, 155.18, 146.09,
133.75, 132.55, 130.37, 129.68, 128.96, 125.24, 120.30, 118.89,
115.52, 111.48 (aromatic & other carbon atoms) 47.00 (CH2),
and 28.93 ppm (CH2).
Anal. Calcd. for C18H13N7OS: C, 57.60; H, 3.49; N, 26.12.
Found: C, 57.52; H, 3.76; N, 26.43.
N-(5-Benzotriazol-1-ylmethyl[1,3,4]thiadiazol-2-yl)-N-(2-oxo-
propyl)benzamide (26c).
This compound was crystallized from ethanol/dimethylfor-
mamide (2:1) as pale brown crystals in 89%, mp 93-95 °C; ir, n
1737 (CO) and 1625 cm- 1 (amide CO); 1H nmr (dimethyl-d6 sul-
foxide): dH 2.31 (s, 3H, Me), 5.47 (s, 2H,CH2), 6.42 (s, 2H,
CH2), and 7.46-8.17 (m, 9H, Ar-H); 13C nmr (dimethyl-d6 sul-
foxide): d 201.52 (CO), 173.90, 166.47, 154.03, 145.00, 136.20,
133.69, 132.32, 130.42, 129.26, 125.40, 120.31, 118.90, and
111.42 (aromatic & other carbon atoms) 59.98 (CH2), 46.99
(CH2) and 28.21 ppm (Me).
Ethyl 4-Benzotraiazol-1-yl-3-phenylhydrazonobutanoate (31).
A solution of compound 30 (2.47 g, 10 mmol) in ethanol (20
mL) was treated with phenylhydrazine (1.08 g, 10 mmol). The
reaction mixture was refluxed for 3 hours, then allowed to cool.
The solid product, so formed, was collected by filtration and
recrystallized from ethanol as yellow crystals in 76% yield; mp.
140-142 °C, ir: n 3443 (NH), 1728 (ester CO); 1H nmr (deuterio-

Sep-Oct 2002
New Derivatives of Benzotriazole as Antimicrobial and Antifungal Agents
883
same volume in wells of all tested microorganisms, bacteria test
plates were incubated at 37 °C for 24 hours and fungal test plates
were incubated at 25 °C for 48 hours. The activities were
expressed as inhibition zones (mm diameter, as clear areas). The
least concentration that showed inhibitory effect on any specific
microorganism was considered as the minimum inhibitory con-
centration (MIC), which was determined using streptomycin and
mycostatin as references.
chloroform): dH 1.28 (t, 3H, J=7 Hz, Me), 3.35 (s, 2H, CH2), 3.75
(q, 2H, J=7 Hz, CH2), 5.56 (s, 2H, CH2) and 6.96-8.09 (m, 9H,
Ar-H) and 8.73 ppm (br, 1H, NH).
Anal. Calcd. for C18H19N5O2: C, 64.08; H, 5.63; N, 20.76.
Found: C, 64.33; H, 5.53; N, 20.77.
5-(Benzotriazol-1-ylmethyl)-2,4-dihydropyrazol-3-one (33).
A suspension of compound 30 (2.47 g, 10 mmol) in ethanol
(20 mL) was treated with hydrazine hydrate (0.5 g, 10 mmol).
The reaction mixture was refluxed for 3 hours then allowed to
cool. The solid product, so formed, was collected by filtration
and recrystallized from ethanol as pale brown crystals in 61%
yield; mp. 139-141 °C, ir: n 1625 cm- 1 (CO); 1H nmr (dimethyl-
d6 sulfoxide): dH 5.20 (s, 2H, CH2), 5.78 (s, 2H, CH2), 7.37-8.04
(m, 4H, Ar-H) and 10.50 ppm (br, 1H, NH, D2O exchangeable);
13C nmr (dimethyl-d6 sulfoxide): dC 158.95 (CO), 146.18,
141.90, 133.40, 128.14, 124.86, 119.69 and 111.33 (aromatic car-
bons), 45.36 (CH2) and 56.95 ppm (CH2).
REFERENCES AND NOTES
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Chem. Soc., 55, 992 (1978).
[2] S. M. El-Khawass and N. S. Habib, J. Heterocyclic Chem.
26, 177 (1989).
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(1957).
[4] S. Rao and A. S. Mitra. Indian J. Chem. 15B, 1060 (1977).
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Chem. Review, 69, 201 (2000).
[9] S. Buttacharya and D. F. Ewing, J. Chem. Perkin Trans. 1,
689 (1994).
Anal. Calcd. for C10H9N5O: C, 55.81; H, 4.22; N, 32.54.
Found: C, 55.63; H, 4.37; N, 32.25.
6-Amino-3-benzotriazol-1-ylmethyl-4-phenyl-1,4-dihydro-
pyrano[2,3-c]pyrazole-5-carbonitrile (34).
To a solution of 33 (2.15 g, 10 mmol) in ethanol (20 mL) ben-
zilidinemalononitrile (1.54 g, 10 mmol) was added. The reaction
mixture was refluxed for 3-4 hours, then left to cool to room tem-
perature. The solid products was collected by filtration and
recrystallized from ethanol as brown crystals (72%); mp. 190-
192 °C. ir: n 3413, 3325 (NH2 and NH) and 2189 cm- 1 (CN); 1H
nmr (dimethyl-d6 sulfoxide): dH 4.58 (s, H, CH), 5.43 (d, 1H,
J=13Hz, CH),5.65 (d, 1H, J=13Hz, CH), 6.98-7.98 (m, 11H, Ar-
H & NH2) and 12.92 ppm (br,1H,NH); 13C nmr (dimethyl-d6 sul-
foxide): dC 161.40, 156.00, 145.89, 144.64, 133.74, 133.14,
131.35, 130.39, 129.25, 128.22, 127.97, 124.82, 121.34, 120.00,
110.89 and 100.50 (aromatic & other carbon atoms), 56.90 (CH2)
and 36.90 ppm (CH).
[10] S. El-Meligie. Indian J. of Chem. 36B, 1126 (1997).
[11] A. Baba, A. Mori, T. Yasuma, S. Unno, H. Makino and T.
Sohda. Chem. Pharm. Bull. 47, 993 (1999).
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J. C. McGuire, D. P. Thompson and T. G. Geary. Bioorganic &
Medicinal Chem. Lett. 9, 1727 (1999).
Anal. Calcd. for C20H15N7O: C, 65.57; H, 4.09; N, 26.54.
Found: C, 65.31; H, 4.49; N, 26.45.
[13] K. Gewald, E. Schinke and H. Bottcher., Chem. Ber. 99,
94 (1966).
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Agrody and H. H. El-Said, J. Chem. Res(s), 322 (1995).
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Biological Testing.
The newly synthesized compounds were tested against the
specified microorganisms, using 400 mg/ml (w/v) solutions in
sterile dimethyl-d6 sulfoxide. A solution of the tested compound
(0.5 mol) was poured aseptically in a well of 6 mm diameter
made by a borer in a seeded agar medium. After pipetting the