Synthesis and antibacterial activity of some new derivatives of thiosemicarbazide and 1,2,4-triazole

Article abstract of DOI:10.1080/10426507.2012.757612

In a reaction of hydrazides of cyclohexylacetic acid 1 and phenylacetic acid 2 with isothiocyanates, respective thiosemicarbazide derivatives 3-18 were obtained. Further cyclization with 2% NaOH led to the formation of 5-(cyclohexylmethyl/benzyl)-4-substituted-2,4-dihydro-3H-1,2, 4-triazole-3-thiones 19-34. Structures of all new products were confirmed by analytical and spectroscopic methods. All compounds were screened for their in vitro activity against some species of bacteria and fungi. [Supplementary materials are available for this article. Go to the publisher's online edition ofPhosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional figures and tables.]

Full text of DOI:10.1080/10426507.2012.757612

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Synthesis and antibacterial activity of some new
derivatives of thiosemicarbazide and 1,2,4-triazole
Monika Wujec a , Anna Pachuta-Stec a , Joanna Stefańska b , Edyta Kuśmierz a & Agata Siwek
a
a Department of Organic Chemistry, Medical University, 4a Chodzki Str., 20-093, Lublin,
Poland
b Department of Pharmaceutical Microbiology, Medical University, Warsaw, Poland
Accepted author version posted online: 02 Jan 2013.
To cite this article: Monika Wujec , Anna Pachuta-Stec , Joanna Stefańska , Edyta Kuśmierz & Agata Siwek (2013): Synthesis
and antibacterial activity of some new derivatives of thiosemicarbazide and 1,2,4-triazole, Phosphorus, Sulfur, and Silicon and
the Related Elements, DOI:10.1080/10426507.2012.757612
To link to this article: http://dx.doi.org/10.1080/10426507.2012.757612
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Synthesis and antibacterial activity of some new derivatives of thiosemicarbazide and 1,2,4-
triazole.
a
aMonika Wujec*, aAnna Pachuta-Stec, bJoanna Stefańska, aEdyta Kuśmierz, Agata Siwek
aDepartment of Organic Chemistry, Medical University, 4a Chodzki Str., 20-093 Lublin, Poland,
bDepartment of Pharmaceutical Microbiology, Medical University, Warsaw, Poland
e-mail: monika.wujec@umlub.pl
O
O
NH2
NH
O
NH
NH
R2
NH R2
NCS
R1
R1
3-18
1,2
N
NH
S
R1
N
R2
19-34
R1 = C6H5, C6H11
2-
R = C H , BrC H , BrC H , FC H , FC H , CH C H , CH C H , C H
2 5
4- 2- 4- 2- 4-
2
6
5
6
4
6
4
6
4
6
4
3
6
4
3
6
4
Abstract: In the reaction of the hydrazides of cyclohexylacetic acid 1 and phenylacetic acid 2
with isothiocyanates, the respective thiosemicarbazide derivatives 3-18 were obtained. Further
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cyclization with 2% NaOH led to the formation of 5-(cyclohexylmethyl/benzyl)-4-substituted-
2,4-dihydro-3H-1,2,4-triazole-3-thiones 19-34. The structures of all new products were
confirmed by analytical and spectroscopic methods. All compounds were screened for their
in vitro activity against some species of bacteria and fungi.
Keywords: Thiosemicarbazides, 1,2,4-triazoles, isothiocyanates, antimicrobial activity.
INTRODUCTION
Infectious diseases and bacterial infections - despite enormous progress, both in their treatment
and prevention - are an increasingly serious medical problem. Practicing physicians are instantly
faced with new, more dangerous strains of bacteria, which is, among others, a result of natural
selection of bacteria resistant to antibiotics. Therefore many research centers are currently
involved in the exploration of new antibacterial and antifungal agents. Our team has been
working for many years with synthesis of derivatives of acetic hydrazides: thio/semicarbazide,
oxo-/mercapto-triazole and we are also still looking for a relationship between their molecular
structure and bioactivity. Where does our interest in these compounds come from? Both
derivatives of thio/semicarbazide and triazole have been reported to exhibit antimicrobial,
fungicidal, anti-inflammatory, antiparasitic, insecticidal, herbicidal, antiviral, antitumor,
anticonvulsant, antidepressant, hypotensive effects and plant growth regulatory activities.1-18
Additionally, the triazole ring has been incorporated into a wide variety of important drugs:
Ribavirin, Rizatriptan, Letrozole, Anastrozole and many antifungal drugs: Fluconazole,
Itraconazole, Posaconazole.
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In continuation of our study on the synthesis of biologically active compounds, in this paper we
present the synthesis and antimicrobial activity of two series of the thiosemicarbazide and
triazole derivatives.
RESULTS AND DISCUSSION
Cyclohexyl acetic acid hydrazide 1 and phenylacetic acid hydrazide 2 were used as starting
materials, which were obtained by the reaction of ethyl ester of the appropriate acids with 80%
hydrazine hydrate18,19. New thiosemicarbazide derivatives 3-18 were obtained by the reaction of
1 and 2 with isothiocyanates. The conditions of the reaction were established experimentally.
Two of thiosemicarbazide of cyclohexylacetic acid (with bromo- and fluoro substituent in
position 2 in phenyl ring) were obtained during heating under reflux for 2 h in ethanol. We tried
to use the same method for all compounds, however without success. The rest of
thiosemicarbazide derivatives were obtained by heating on the oil bath for 8 h.
The thiosemicarbazides 3-18 were subjected to cyclization in a 2% aqueous solution of sodium
hydroxide yielding the corresponding 5-(cyclohexylmethyl/benzyl)-4-substituted-2,4-dihydro-
3H-1,2,4-triazole-3-thiones 19-34. The reactions were performed according to Scheme 1.
[Insert Scheme 1]
The structures of the obtained products 3-34 were confirmed by elemental analysis as well as by
the 1H NMR spectra. The 1H NMR spectra of the thiosemicarbazide derivatives 3-18 showed the
signals of the proton linked to nitrogen atoms at 7.78-10.32 ppm. In the respective triazoles 19-
34, the signal of the NH proton was observed in the range of 13.47-13.97 ppm. All obtained
triazoles are present in the thione form according their NMR spectra (absence of a signal of the
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proton linked to sulfur). Substituents and corresponding yields of the intermediates 3-18 as well
as the products 19-34 are collected in Tables 1 and 2, respectively.
[Insert Table 1]
[Insert Table 2]
Biological Activity
The in vitro antimicrobial activities of all synthesized compounds at concentrations ranging from
400 to 6.25 µg/mL were screened using the agar dilution method against some Gram-negative
and Gram-positive reference species of bacteria and a few species of fungi.
Among all tested compounds, only two derivatives of thiosemicarbazide 12 and 16 and one
triazole derivative 29 showed antimicrobial activity. Among them, the most active against Gram-
positive species was compound 29 (triazole with 4-bromophenyl substituent) with MIC in the
range 50-200 µg/mL. Two derivatives of thiosemicarbazide showed inhibitory action against
Gram-positive species at somewhat higher concentration (MIC=200-400 µg/mL) (Tables S 1 and
S 2, Supplemental Materials). Moreover, compound 16 showed inhibitory effect against Candida
albicans ATCC 10231 and ATCC 90028 with MIC = 200 µg/mL and 400 µg/mL, respectively
and it was active against most clinical strains of fungi (Table S 3).
In conclusion, our data showed that compounds with phenyl substitution were weakly active
whereas the analogs with cyclohexyl ring were inactive. It is possible that, firstly, different
conformations of cyclohexyl ring are not suitable for microbiological activity. Secondly,
privileged position of substituent in phenyl ring is ortho, but the kind of substituent (electron-
donating or electron-withdrawing) in this case is irrelevant.
EXPERIMENTAL
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Chemistry
Melting points were determined in Fisher-Johns blocs and presented without any corrections.
The 1H NMR spectra were recorded on a Brucker Avance 300 in DMSO-d6 with TMS as internal
standard. Chemicals were purchased from Lancaster or Merck Co. and used without further
purification. Purity and progress of reaction were checked by TLC on Merck Co. plates
Aluminium oxide 60 F254 in a CHCl3/C2H5OH (10:1) solvent system with UV visualization.
1-[(cyclohexyl/phenyl)acetyl]-4-substituted thiosemicarbazide 3-18
Method for compounds 3,5,8-10
The hydrazide of cyclohexylacetic acid (1, 0.01 mol) and the appropriate isothiocyanate (0.01
mol) was heated at the 60-70ºC for 8 h. Then the unreacted isothiocyanate was removed by
washing with diethyl ether. The obtained crude product was dried and recrystallized to give pure
product.
Method for compound 7
The hydrazide of cyclohexylacetic acid (1, 0.01 mol) and the 4-fluorophenylisothiocyanate (0.01
mol) was heated at the 100ºC for 10 h. Then the unreacted isothiocyanate was removed by
washing with diethyl ether. The obtained crude product was dried and recrystallized to give pure
product.
Method for compounds 4,6
The hydrazide of cyclohexylacetic acid (1, 0.01 mol) and the (2-bromo/2-
fluoro)phenylisothiocyanate (0.01 mol) in 20 mL ethanol was heated under reflux for 2 h.
Precipitated compound was filtered off and crystallized from ethanol.
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Method for compounds 11-18
The hydrazide of phenylacetic acid (2, 0.01 mol) and the appropriate isothiocyanate (0.01 mol)
was heated on oil bath at temperature 40-50ºC for 12 h. The product was washed with Et2O to
remove the unreacted isothiocyanate, dried and crystallized from EtOH.
1-cyclohexylacetyl-4-phenylthiosemicarbazide 3
mp 170-172ºC. 1H-NMR (DMSO-d6) δ: 0.91-0.98 (m, 2H, CH2), 1.13-1.27 (m, 4H, 2CH2), 1.62-
1.87 (m, 4H, 2CH2), 1.89 (s, 1H, CH), 2.04, 2.07 (d, 2H, CH2, J= 6.7 Hz), 7.12-7.45 (m, 5H,
arom. benz.), 9.53 (bs, 2H, 2NH), 9.80 (s, 1H, NH). Anal. Calcd for C15H21N3OS: 291.41, C,
61.82; H, 7.26; N, 14.42. Found: C, 61.92; H, 7.21; N, 14.43.
1-cyclohexylacetyl-4-(2-bromophenyl)thiosemicarbazide 4
mp 158-159ºC. 1H-NMR (DMSO-d6) δ: 0.96-1.13 (m, 2H, CH2), 1.14-1.29 (m, 4H, 2CH2), 1.68-
1.79 (m, 4H, 2CH2), 1.93 (s, 1H, CH), 2.11, 2.13 (d, 2H, CH2, J= 6.7 Hz), 7.21-7.73 (m, 4H,
arom. benz.), 9.48 (s, 2H, 2NH), 9.98 (s, 1H, NH). Anal. Calcd for C15H20BrN3OS: 370.31, C,
48.65; H, 5.44; N, 11.35. Found: C, 48.62; H, 5.41; N, 11.41.
1-cyclohexylacetyl-4-(4-bromophenyl)thiosemicarbazide 5
mp 182-183ºC. 1H-NMR (DMSO-d6) δ: 0.87-1.03 (m, 2H, CH2), 1.05-1.27 (m, 4H, 2CH2), 1.62-
1.72 (m, 4H, 2CH2), 1.90(s, 1H, CH), 2.04, 2.06 (d, 2H, CH2, J= 6.6 Hz), 7.42-7.52 (m, 4H,
arom. benz.), 9.63 (bs, 2H, 2NH), 9.81 (s, 1H, NH) (Figure S1). Anal. Calcd for C15H20BrN3OS:
370.31, C, 48.65; H, 5.44; N, 11.35. Found: C, 48.64; H, 5.41; N, 11.38.
1-cyclohexylacetyl-4-(2-fluorophenyl)thiosemicarbazide 6
1
mp 123-125ºC. H-NMR (DMSO-d6) δ: 0.87-1.09 (m, 2H, CH2), 1.13-1.27 (m, 2H, CH2), 1.30
(s, 1H, CH), 1.62-1.72 (m, 6H, 3CH2), 2.04, 2.06 (d, 2H, CH2, J= 6.6 Hz), 7.14-7.37 (m, 4H,
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arom. benz.), 9.30, 9.69, 9.88 (3s, 3H, 3NH). Anal. Calcd for C15H20FN3OS: 309.40, C, 58.23; H,
6.52; N, 13.58. Found: C, 58.25; H, 6.51; N, 13.59.
1-cyclohexylacetyl-4-(4-fluorophenyl)thiosemicarbazide 7
mp 123-125ºC. 1H-NMR (DMSO-d6) δ: 1.04-1.24 (m, 6H, 3CH2), 1.68-1.73 (m, 4H, 2CH2), 1.78
(s, 1H, CH), 2.10, 2.12 (d, 2H, CH2, J= 6.6 Hz), 7.18-7.50 (m, 4H, arom. benz.), 9.35, 9.76, 9.98
(3s, 3H, 3NH). Anal. Calcd for C15H20FN3OS: 309.40, C, 58.23; H, 6.52; N, 13.58. Found: C,
58.23; H, 6.50; N, 13.59.
1-cyclohexylacetyl-4-(2-methylphenyl)thiosemicarbazide 8
1
mp 168-170ºC. H-NMR (DMSO-d6) δ: 0.89-1.11 (m, 2H, CH2), 1.13-1.27 (m, 2H, CH2), 1.30
(s, 1H, CH), 1.62-1.72 (m, 6H, 3CH2), 2.04, 2.06 (d, 2H, CH2, J= 6.6 Hz), 2.32 (, 3H, CH3),
7.15-7.42 (m, 4H, arom. benz.), 8.87, 9.52, 9.98 (3s, 3H, 3NH). Anal. Calcd for C16H23N3OS:
359.44, C, 62.92; H, 7.59; N, 13.76. Found: C, 62.93; H, 7.51; N, 13.77.
1-cyclohexylacetyl-4-(4-methylphenyl)thiosemicarbazide 9
1
mp 158-160ºC. H-NMR (DMSO-d6) δ: 0.80-0.98 (m, 2H, CH2), 1.03-1.26 (m, 2H, CH2), 1.30
(s, 1H, CH), 1.61-1.89 (m, 6H, 3CH2), 2.03, 2.06 (d, 2H, CH2, J= 6.6 Hz), 2.27 (, 3H, CH3),
7.10, 7.13, 7.28, 7.31 (dd, 4H, arom. benz. J= 7.7 Hz), 8.89, 9.46, 9.77 (3s, 3H, 3NH). Anal.
Calcd for C16H23N3OS: 359.44, C, 62.92; H, 7.59; N, 13.76. Found: C, 62.94; H, 7.56; N, 13.77.
1-cyclohexylacetyl-4-ethylthiosemicarbazide 10
mp 184-185ºC. 1H-NMR (DMSO-d6) δ: 0.83-0.96 (m, 2H, CH2), 1.02, 1.04, 1.07 (t, 3H, CH3 J=
7.4 Hz), 1.13-1.25 (m, 2H, CH2), 1.27 (s, 1H, CH), 1.62-1.69 (m, 6H, 3CH2), 1.99, 2.01 (d, 2H,
CH2, J= 6.7 Hz), 3.39, 3.42, 3.44, 3.46 (q, 2H, CH2), 7.78, 9.03, 9.57 (3s, 3H, 3NH). Anal. Calcd
for C11H21N3OS: 243.37, C, 54.29; H, 8.70; N, 17.27. Found: C, 54.31; H, 8.69; N, 17.27.
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1-phenylacetyl-4-phenylthiosemicarbazide 1119
1-phenylacetyl-4-(2-bromophenyl)thiosemicarbazide 12
mp 149-151ºC.1H NMR (DMSO-d6) δ: 3.59 (s, 2H, CH2), 7.22-7.73 (m, 9H, CHarom.), 9.52, 9.82,
10.32 (3s, 3H, 3NH). Anal. Calcd for C15H14BrN3OS: 364.26, C, 49.46; H, 3.87; N, 11.54.
Found: C, 49.51; H, 3.69; N, 11.27.
1-phenylacetyl-4-(4-bromophenyl)thiosemicarbazide 1319
1-phenylacetyl-4-(2-fluorophenyl)thiosemicarbazide 14
mp 156-158ºC. 1H NMR (DMSO-d6) δ: 3.57 (s, 2H, CH2), 7.21-7.43 (m, 9H, CHarom.), 9.58,
9.83, 10.29 (3s, 3H, 3NH). Anal. Calcd for C15H14FN3OS: 303.35, C, 59.39; H, 4.65; N, 13.85.
Found: C, 59.50; H, 4.69; N, 13.86.
1-phenylacetyl-4-(4-fluorophenyl)thiosemicarbazide 15
mp 158-160ºC. 1H NMR (DMSO-d6) δ: 3.58 (s, 2H, CH2), 7.19-7.50 (m, 9H, CHarom.), 9.68,
9.76, 10.22 (3s, 3H, 3NH). Anal. Calcd for C15H14FN3OS: 303.35, C, 59.39; H, 4.65; N, 13.85.
Found: C, 59.47; H, 4.72; N, 13.85.
1-phenylacetyl-4-(2-methylphenyl)thiosemicarbazide 16 19
1-phenylacetyl-4-(4-methylphenyl)thiosemicarbazide 17
mp 154-156ºC. 1H NMR (DMSO-d6) δ: 2.34 (s, 3H, CH3), 3.58 (s, 2H, CH2), 7.18-7.42 (m, 9H,
CHarom.), 9.58, 9.66, 10.19 (3s, 3H, 3NH). Anal. Calcd for C16H17N3OS: 299.39, C, 64.19; H,
5.72; N, 14.04. Found: C, 64.20; H, 5.69; N, 13.99.
1-phenylacetyl-4-ethylthiosemicarbazide 1819
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5-cyclohexylmethyl/benzyl-4-substituted-2,4-dihydro-3H-1,2,4-triazole-3-thione 19-34
General procedure
Thiosemicarbazide 3-18 (0.01 mol) was dissolved in 2% aqueous NaOH (40-50 mL) and
refluxed for 2h. After cooling, the solution was filtered and neutralized with dilute hydrochloric
acid. The precipitate was filtered off and crystallized from EtOH.
1
5-cyclohexylmethyl-4-phenyl-2,4-dihydro-3H-1,2,4-triazole-3-thione 19: mp 172-174ºC. H-
NMR (DMSO-d6) δ: 0.72-0.97 (m, 2H, CH2), 1.00-1.27 (m, 4H, 2CH2), 1.38-1.64 (m, 4H,
2CH2), 1.66 (s, 1H, CH), 2.30, 2.33 (d, 2H, CH2, J= 6.7 Hz), 7.36-7.61 (m, 5H, CHarom.), 13.70
(s, 1H, NH). Anal. Calcd for C15H19N3S: 273.40, C, 65.90; H, 7.00; N, 15.37. Found: C, 65.92;
H, 7.01; N, 15.37.
5-cyclohexylmethyl-4-(2-bromophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 20: mp 215-
216ºC. 1H-NMR (DMSO-d6) δ: 0.90-0.98 (m, 2H, CH2), 1.14-1.30 (m, 4H, 2CH2), 1.69-1.78 (m,
4H, 2CH2), 1.90 (s, 1H, CH), 2.11, 2.13 (d, 2H, CH2, J= 6.6 Hz), 7.55-7.95 (m, 4H, arom. benz.),
13.84 (s, 1H, NH). Anal. Calcd for C15H18BrN3S: 352.29, C, 51.14; H, 5.15; N, 11.93. Found: C,
51.17; H, 5.21; N, 11.97.
5-cyclohexylmethyl-4-(4-bromophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 21: mp 128-
1
130ºC. H-NMR (DMSO-d6) δ: 0.74-0.84 (m, 2H, CH2), 1.04-1.14 (m, 2H, CH2), 1.24 (s, 1H,
CH), 1.39-1.64 (m, 6H, 3CH2), 2.27, 2.29 (d, 2H, CH2, J= 6.7 Hz), 7.26, 7,29, 7,69, 7.72 (dd,
4H, CHarom J=8.7 Hz), 13.80 (s, 1H, NH) (Figure S2). Anal. Calcd for C15H18BrN3S: 352.29, C,
51.14; H, 5.15; N, 11.93. Found: C, 51.14; H, 5.19; N, 11.94.
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5-cyclohexylmethyl-4-(2-fluorophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 22: mp 222-
1
224ºC. H-NMR (DMSO-d6) δ: 0.77-0.89 (m, 2H, CH2), 1.02-1.15 (m, 2H, CH2), 1.28 (s, 1H,
CH), 1.37-1.55 (m, 6H, 3CH2), 2.27, 2.30 (d, 2H, CH2, J= 6.7 Hz), 7.39-7,67 (m, 4H, CHarom),
13.82 (s, 1H, NH). Anal. Calcd for C15H18FN3S: 291.39, C, 61.83; H, 6.23; N, 14.42. Found: C,
61.85; H, 6.34; N, 14.44.
5-cyclohexylmethyl-4-(4-fluorophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 23: mp 180-
182ºC. 1H-NMR (DMSO-d6) δ: 1.04-1.25 (m, 6H, 3CH2), 1.66-1.73 (m, 4H, 2CH2), 1.79 (s, 1H,
CH), 2.10, 2.12 (d, 2H, CH2, J= 6.6 Hz), 7.46-7.59 (m, 4H, CHarom), 13,89 (s, 1H, NH). Anal.
Calcd for C15H18FN3S: 291.39, C, 61.83; H, 6.23; N, 14.42. Found: C, 61.83; H, 6.25; N, 14.48.
5-cyclohexylmethyl-4-(2-methylphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 24: mp 172-
1
174ºC. H-NMR (DMSO-d6) δ: 0.76-0.96 (m, 2H, CH2), 1.13-1.25 (m, 2H, CH2), 1.30 (s, 1H,
CH), 1.60-1.84 (m, 6H, 3CH2), 2.02, 2.04 (d, 2H, CH2, J= 6.6 Hz), 2.50 (s, 3H, CH3), 7.29-7.57
(m, 4H, arom. benz.), 13,81 (s, 1H, NH). Anal. Calcd for C16H21N3S: 287.42, C, 66.86; H, 7.36;
N, 14.62. Found: C, 66.83; H, 7.35; N, 14.58.
5-cyclohexylmethyl-4-(4-methylphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 25: mp 88-92ºC.
1H-NMR (DMSO-d6) δ: 0.76-0.97 (m, 2H, CH2), 1.04-1.27 (m, 2H, CH2), 1.42 (s, 1H, CH),
1.51-1.76 (m, 6H, 3CH2), 2.28, 2.31 (d, 2H, CH2, J= 6.7 Hz), 2.39 (s, 3H, CH3), 7.22, 7.25, 7.35,
7.37 (dd, 4H, CHarom J=8.3 Hz), 13,67 (s, 1H, NH). Anal. Calcd for C16H21N3S: 287.42, C, 66.86;
H, 7.36; N, 14.62. Found: C, 66.88; H, 7.39 N, 14.62.
5-cyclohexylmethyl-4-ethyl-2,4-dihydro-3H-1,2,4-triazole-3-thione 26: mp 129-132ºC. 1H-NMR
(DMSO-d6) δ: 0.94-1.11 (m, 2H, CH2), 1.16, 1.19, 1.21 (t, 3H, CH3 J=7.1 Hz), 1.23-1.27 (m, 2H,
CH2), 1.28 (s, 1H, CH), 1.60-1.78 (m, 6H, 3CH2), 2.54, 2.56 (d, 2H, CH2, J= 6.7 Hz), 3.91, 3.93,
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3.96, 3.98 (q, 2H, CH2 J= 7.1 Hz), 13,47 (s, 1H, NH). Anal. Calcd for C11H19N3S: 225.35, C,
58.63; H, 8.50; N, 18.65. Found: C, 58.68; H, 8.49 N, 18.62.
5-benzyl-4-phenyl-2,4-dihydro-3H-1,2,4-triazole-3-thione 2719
5-benzyl-4-(2-bromophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 28 : mp 230-232ºC.
1H NMR (DMSO-d6) δ: 3.73 (q, 2H, CH2 J =16.26 Hz), 6.96-7.88 (m, 9H, CHarom.), 13.90 (s, 1H,
NH). Anal. Calcd for C15H12BrN3S: 346.24, C, 52.03; H, 3.49; N, 12.14. Found: C, 52.20; H,
3.69; N, 12.16.
5-benzyl-4-(4-bromophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 2919
5-benzyl-4-(2-fluorophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 30: mp 204-206ºC.
1H NMR (DMSO-d6) δ: 3.83 (q, 2H, CH2 J =16.00 Hz), 6.91-7.66 (m, 9H, CHarom.), 13.97 (s, 1H,
NH). Anal. Calcd for C15H12FN3S: 285.34, C, 63.14; H, 4.24; N, 14.73. Found: C, 63.15; H,
4.29; N, 14.87.
5-benzyl-4-(4-fluorophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 31: mp 199-201ºC.
1H NMR (DMSO-d6) δ: 3.92 (s, 2H, CH2), 6.97-7.43 (m, 9H, CHarom.), 13,88 (s, 1H, NH). . Anal.
Calcd for C15H12FN3S: 285.34, C, 63.14; H, 4.24; N, 14.73. Found: C, 63.25; H, 4.25; N, 14.70.
5-benzyl-4-(2-methylphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 3219
5-benzyl-4-(4-methylphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 33: mp 182-184ºC.
1H NMR (DMSO-d6) δ: 2.42 (s, 3H, CH3), 3.89 (s, 2H, CH2), 6.99-7.35 (m, 9H, CHarom.), 13,79
(s, 1H, NH). . Anal. Calcd for C16H15N3S: 281.37, C, 68.30; H, 5.37; N, 14.93. Found: C, 63.19;
H, 5.29; N, 14.96.
5-benzyl-4-ethyl-2,4-dihydro-3H-1,2,4-triazole-3-thione 3419
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Microbiology
The following microorganisms were used in this study: Staphyloccocus aureus NCTC 4163, S.
aureus ATCC 25923, S. aureus ATCC 6538, S. aureus ATCC 29213, .S epidermidis ATCC
12228, Bacillus subtilis ATCC 6633, B. cereus ATCC 11778, Micrococcus luteus ATCC 9341,
M. luteus ATCC 10240, Enterococcus. feacalis ATTC 29212, E. hirae ATCC 10541 (as
representative examples of Gram-positive bacteria) and Escherichia coli ATCC 10538, E. coli
ATCC 25922, E. coli NCTC 8196, Proteus vulgaris NCTC 4635, Pseudomonas aeruginosa
ATCC 15442, P. aeruginosa NCTC 6749, P. aeruginosa ATCC 27853, Bordetella
bronchiseptica ATCC 4617 (as representative examples of Gram-negative bacteria) and for 15
strains of fungi (Candida albicans ATCC 90028, Candida albicans ATCC 10231, Candida
parapsilosis ATCC 22019, thirteen clinical isolates of C. albicans from the Department of
Pharmaceutical Microbiology of Warsaw Medical University).
Initially, antibacterial activity was screened on the basis of growth inhibition zone (giz) utilizing
the disc diffusion method. For compounds showing the inhibitory effect on the growth of tested
bacteria, monitored as an appearance of giz, the minimal inhibitory concentrations (MICs) were
determined as the lowest concentration of the compound preventing growth of the tested
microorganism using agar dilution method20-21. Ciprofloxacin, antibiotic widely used in the
treatment of infections diseases, was used as control antimicrobial agent.
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Scheme 1:
O
O
NH2
NH
O
NH
NH
R2
NH
R2
NCS
R1
R1
3-18
1,2
N
NH
R1
N
S
R2
19-34
R1 = C6H5, C6H11
2-
R = C H , BrC H , BrC H , FC H , FC H , CH C H , CH C H , C H
2 5
4- 2- 4- 2- 4-
2
6
5
6
4
6
4
6
4
6
4
3
6
4
3
6
4
Table 1. Substituents and yields of thiosemicarbazide derivatives
Intermediate
R1
R2
Yield %
88
3
4
5
C6H11 C6H5
C6H11 2-BrC6H4
C6H11 4-BrC6H4
92
93
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6
C6H11 2-FC6H4
C6H11 4-FC6H4
94
89
7
8
C6H11 2-CH3C6H4 78
C6H11 4-CH3C6H4 86
9
10
11
12
13
14
15
16
17
18
C6H11 C2H5
80
95
85
89
87
89
C6H5 C6H5
C6H5 2-BrC6H4
C6H5 4-BrC6H4
C6H5 2-FC6H4
C6H5 4-FC6H4
C6H5 2-CH3C6H4 90
C6H5 4-CH3C6H4 93
C6H5 C2H5
93
Table 2. Substituents and yields of triazole derivatives
Product
R1
R2
Yield %
86
19
20
21
22
C6H11 C6H5
C6H11 2-BrC6H4
C6H5 4-BrC6H4
C6H5 2-FC6H4
89
87
90
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23
24
25
26
27
28
29
30
31
32
33
34
C6H11 4-FC6H4
90
C6H11 2-CH3C6H4 86
C6H11 4-CH3C6H4 88
C6H11 C2H5
76
84
87
82
79
80
C6H5 C6H5
C6H5 2-BrC6H4
C6H5 4-BrC6H4
C6H5 2-FC6H4
C6H5 4-FC6H4
C6H5 2-CH3C6H4 81
C6H5 4-CH3C6H4 83
C6H5 C2H5
84
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