Synthesis, characterization and antibacterial activity of some triazole Mannich bases carrying diphenylsulfone moieties

Article abstract of DOI:10.1016/j.ejmech.2008.07.003

A series of Mannich bases of 4-substituted 5-[4-(4-X-phenylsulfonyl)phenyl]-2,4-dihydro-3H-1,2,4-triazole-3-thiones, X = H, Cl, Br, 3 and 5 were synthesized and characterized on the basis of IR, NMR and elemental analyses. The potential antibacterial effe

Full text of DOI:10.1016/j.ejmech.2008.07.003

European Journal of Medicinal Chemistry 44 (2009) 3083–3089
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Short communication
Synthesis, characterization and antibacterial activity of some
triazole Mannich bases carrying diphenylsulfone moieties
,
a
b
Gabriela Laura Almajan a , Stefania-Felicia Barbuceanu , Eva-Ruxandra Almajan ,
*
Constantin Draghici c, Gabriel Saramet d
a Organic Chemistry Department, Faculty of Pharmacy, Traian Vuia Street 6, 020956 Bucharest, Romania
b Horia Hulubei National Institute of Physics and Nuclear Engineering IRASM, Radiation Processing Center,
Microbiological Laboratory, Atomistilor Street 407, P.O. Box MG-6, Bucharest-Magurele, Romania
c C.D.Nenitescu Institute of Organic Chemistry, Romanian Academy, Splaiul Independentei 202B, 060023 Bucharest, Romania
d Pharmaceutical Techniques and Drug Industry Department, Faculty of Pharmacy, Traian Vuia Street 6, 020956 Bucharest, Romania
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of Mannich bases of 4-substituted 5-[4-(4-X-phenylsulfonyl)phenyl]-2,4-dihydro-3H-1,2,4-tri-
azole-3-thiones, X ¼ H, Cl, Br, 3 and 5 were synthesized and characterized on the basis of IR, NMR and
elemental analyses. The potential antibacterial effects of the synthesized compounds were investigated
using the Acinetobacter baumanii ATCC 19606; Citrobacter freundii ATCC 8090; Pseudomonas aeruginosa
ATCC 9027; Enterococcus faecalis ATCC 19433; Staphylococcus aureus ATCC 12600; Staphylococcus epi-
dermidis ATCC 14990; Bacillus subtilis ATCC 6633 strains. Some of them exhibited promising activities
against A. baumanii and B. subtilis.
Received 28 March 2008
Received in revised form 28 June 2008
Accepted 8 July 2008
Available online 12 July 2008
Keywords:
4-Substituted-1,2,4-triazole-3-thiones
Mannich bases
Ó 2008 Elsevier Masson SAS. All rights reserved.
(Phenylsulfonyl)phenyl moiety
Antibacterial activity
1. Introduction
activities. We have recently reported a few heterocyclic analogues
carrying diphenylsulfone moiety as potent inhibitors of carbonic
Literature survey revealed triazole derivatives which belong to
an important group of heterocyclic compounds, that have been the
subject of extensive study in the recent past. Diverse biological
activities, such as antibacterial, antifungal, anti-inflammatory,
antihypertensive and antiviral have been associated with 1,2,4-
triazole derivatives [1–8].
Mannich reaction is a three-component condensation reaction
involving an active hydrogen containing compound, formaldehyde
and a secondary amine [9]. The aminomethylation of aromatic
substrates by Mannich reaction is of considerable importance for the
synthesis and modification of biologically active compounds [10].
In recent years, Mannich bases have gained importance due to
their application in pharmaceutical chemistry. They have been
found to possess antibacterial, antifungal, anticancer [11,12], anti-
tubercular [13], analgesic and anti-inflammatory [14] properties.
Further, diphenylsulfone derivatives were also found to possess
antibacterial activity [15,16].
anhydrase isozymes I, II and IX [17].
Keeping this observation in view and in continuation of our
work on the synthesis of biologically active nitrogen and sulphur
containing heterocycles [18,19], this paper presents the synthesis of
a series of Mannich bases of 4-substituted 5-[4-(4-X-phenyl-
sulfonyl)phenyl]-2,4-dihydro-3H-1,2,4-triazole-3-thiones and the
study of their antibacterial activity.
2. Chemistry
The reaction sequences employed for synthesis of title
compounds are shown in Scheme 1. The key intermediates, 5-[4-
(4-X-phenylsulfonyl)phenyl]-4-n-propyl-2,4-dihydro-3H-1,2,4-tri-
azole-3-thiones 3a–c, X ¼ H, Cl, Br and 4-amino-5-[4-(4-X-
phenylsulfonyl)phenyl]-2,4-dihydro-3H-1,2,4-triazole-3-thiones 5,
X ¼ H, Cl were prepared from substituted benzoic acid hydrazides
1a–c according to the literature [20,21].
The incorporation of diphenylsulfone moiety into various
heterocyclic systems was found to increase their biological
Transformation of 4-amino-1,2,4-triazole 5 into Mannich bases
is possible after the protection of the exocyclic amino group via
condensation, because this nucleus has two susceptible position for
aminomethylation: nitrogen N(2) endocyclic atom and NH2
exocyclic group. The triazole 5 was condensed with various
aromatic aldehydes in the presence of glacial acetic acid to afford
* Corresponding author. Tel.: þ40 741 095490; fax: þ40 21 3180729.
E-mail address: laura.almajan@gmail.com (G.L. Almajan).
0223-5234/$ – see front matter Ó 2008 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2008.07.003

3084
G.L. Almajan et al. / European Journal of Medicinal Chemistry 44 (2009) 3083–3089
O
O
C3H7NCS
1) CS2/KOH
2) N2H485%
X
S
C
ethanol
reflux
NHNH2
O
1a-c
X=H,Cl,Br
O
S
HN NH
O
S
N
NH
X
C
O
C
S
NHC3H7
X
S
N
O
O
2a-c
5
NH2
X=H,Cl,Br
NaOH 8%
NH
X=H,Cl
ArCH=O
CH3COOH
O
S
N
O
S
N
NH
X
X
S
N
S
N
N
O
O
3a-c
CH2CH2CH3
6a-f
X=H,Cl
C
H
Ar
X=H,Cl,Br
morpholine
morpholine
CH2O 37%
reflux
CH2O 37%
reflux
H2
H2
C
N
O
C
N
O
O
S
N
N
O
S
N
N
X
X
S
N
N
S
N
O
O
Ar
C
CH2CH2CH3
7a-f
X=H,Cl
4a-c
H
X=H,Cl,Br
Ar =
H3CO
N(CH3)2
NO2
O
Scheme 1.
a
series of 4-(substituted-arylidene)amino-5-[4-(4-X-phenyl-
one active hydrogen with formaldehyde and the secondary amine
(morpholine). The condensation can occur using two pathways:
first, the amine reacts with formaldehyde to give condensation
product (A), which attacks the substrate, 3,4,5-trisubstituted-1,2,4-
triazole. The reaction does not normally follow the other possible
route (path 2); however, some successful reaction between
hydroxymethyl derivatives (B) and alkylamines to give Mannich
base can take place. If the nucleophilicity of the carbanion derived
from the labile hydrogen compound is greater than that of amine,
formation of a hydroxymethyl derivative (B) would be favoured
over formation of derivative (A).
sulfonyl)phenyl]-2,4-dihydro-3H-1,2,4-triazole-3-thiones 6a–f.
The title compounds, 4-arylideneamino-5-[4-(4-X-phenylsul
fonyl)phenyl]-2-(morpholin-4-ylmethyl)-2,4-dihydro-3H-1,2,4-tri-
azole-3-thione 7a–f were synthesized in one pot multi-component
Mannich reaction involving 6a–f, formaldehyde and morpholine in
ethanol medium.
Aminomethylation products 4a–c were synthesized through
direct condensation of triazoles 3a–c with morpholine and form-
aldehyde in methanol medium.
3. Biological activity
The structural assignments of new compounds were based on
their elemental analysis and spectral (IR, 1H NMR and 13C NMR)
data. The characterization data of all the new compounds are
summarized in Table 1.
The IR spectrum of compounds 6a–f showed an absorption band
at 1600–1611 cmꢀ1 indicating the presence of C]N in the ring. The
absorption band observed at 3305–3285 cmꢀ1 could be attributed
to an NH group and indicated the easy thione–thiol tautomerism.
In the 1H NMR spectra of Schiff bases 6a–f, a singlet corre-
sponding to one proton characteristic of the N]CH group was
The synthesized compounds were tested for their in vitro
antibacterial activity against the Gram-positive and the Gram-
negative bacteria: Acinetobacter baumanii ATCC 19606; Citrobacter
freundii ATCC 8090; Pseudomonas aeruginosa ATCC 9027; Entero-
coccus faecalis ATCC 19433; Staphylococcus aureus ATCC 12600;
Staphylococcus epidermidis ATCC 14990; Bacillus subtilis ATCC 6633
using the paper disc diffusion method [22] (for the qualitative
determination) and the serial dilutions in liquid broth method
[23] for determination of MIC. Chloramphenicol was used as
control drug.
observed at
d
¼ 9.21–10.16 ppm. The AB coupling of the protons of
the para-substituted phenyl ring resulted in the formation of the
doublets at 8.02–8.10 ppm (J ¼ 8.1–8.8 Hz) and 8.10–8.14 ppm
(J ¼ 8.1–8.8 Hz), respectively. The proton of the furan ring in 6e
resonated as two broad doublets at 8.06 ppm (J ¼ 1.8 Hz) and
7.40 ppm (J ¼ 3.5 Hz), respectively, and as one doublet of doublets
at 6.78 ppm (J ¼ 3.5; 1.8 Hz), integrating for three protons. The
4. Results and discussions
4.1. Chemistry
The Mannich reaction (Scheme 2) consist of the condensation of
a substrate (3,4,5-trisubstituted-1,2,4-triazole) possessing at least
methyl protons of 6b and d appeared as a singlet at
3.02 ppm, respectively.
d
¼ 3.87 and

G.L. Almajan et al. / European Journal of Medicinal Chemistry 44 (2009) 3083–3089
3085
Path 1
H
N
O
H
H
H
H
C
H
H2C
OH2
N
O
C
O
O
H
H2C
N
O
H2C
N
O
-H2O
A
H
N
N
N
H2
C
N
O
S
N
N
S
N
N
Mannich base
Path 2
H2
H2
C
H
OH
C
S
N
O
HN
O
N
N
N
N
N
H2C
O
+
S
-H2O
S
N
N
N
Mannich base
B
Scheme 2.
The attributions of the signals 13C NMR of 6a–f resulted from the
2D-HETCOR spectra. The N]CH signal appears at 153.43–
159.44 ppm and the C(3) and C(5) heterocyclic carbon resonated at
w163 and 146–148 ppm, respectively.
In the IR spectra of Mannich bases 4a–c and 7a–f, the absorption
band at 1247–1243 and 1222–1248 cmꢀ1 could be attributed to the
C]S functional group. The peaks at 2831–2978 cmꢀ1 region were
due to the presence of alkyl group (CHa3s,s; CH2as,s). The absorption
Table 1
Characterization data of compounds 4a–c, 6a–f, 7a–f
Compound
X
Ar
Molecular formula
Molecular mass
M.p. (ꢁC)
Yield (%)
Elemental analysis found (calcd.)
C
H
N
4a
4b
4c
6a
6b
6c
6d
6e
6f
H
Cl
Br
H
H
H
H
H
Cl
H
H
H
H
H
Cl
–
C
C
22H26N4O3S2
458.60
493.04
537.50
420.51
450.53
465.50
463.58
410.47
454.95
519.64
549.66
564.64
562.71
509.60
544.08
177–179
126–128
125–126
209–210
262–263
219–221
239–240
201–202
229–230
185–187
254–256
231–233
248–250
226–227
218–220
87
87
79
67
75
74
58
57
57
69
76
78
76
78
64
57.72
5.62
12.29
(57.62)
(53.59)
(49.16)
(59.98)
(58.65)
(54.18)
(59.59)
(55.60)
(55.44)
(60.10)
(59.00)
(55.31)
(59.76)
(56.57)
(56.36)
(5.71)
(12.22)
–
22H25ClN4O3S2
53.68
49.27
59.90
58.59
54.13
59.51
55.52
55.38
60.04
58.96
55.26
59.70
56.50
56.30
5.05
4.62
3.96
4.12
3.30
4.65
3.51
3.39
4.91
4.99
4.35
5.41
4.60
4.42
11.44
11.36
10.50
(5.11)
(4.69)
(3.84)
(4.03)
(3.25)
(4.57)
(3.44)
(3.32)
(4.85)
(4.95)
(4.28)
(5.37)
(4.55)
(4.37)
–
C22H25BrN4O3S2
C21H16N4O2S2
C22H18N4O3S2
C21H15N5O4S2
C23H21N5O2S2
C19H14N4O3S2
C21H15ClN4O2S2
C26H25N5O3S2
C27H27N5O4S2
C26H24N6O5S2
C28H30N6O3S2
C24H23N5O4S2
C26H24ClN5O3S2
(10.42)
(13.32)
(12.44)
(15.04)
(15.11)
(13.65)
(12.31)
(13.48)
(12.74)
(14.88)
(14.94)
(13.74)
(12.64)
C6H5
13.26
12.36
14.97
15.04
13.59
12.25
13.42
12.69
14.82
14.88
13.69
12.59
2-CH3O–C6H4
3-NO2–C6H4
4-(CH3)2N–C6H4
Furyl
C6H5
7a
7b
7c
7d
7e
7f
C6H5
2-CH3O–C6H4
3-NO2–C6H4
4-(CH3)2N–C6H4
Furyl
C6H5

3086
G.L. Almajan et al. / European Journal of Medicinal Chemistry 44 (2009) 3083–3089
bands corresponding to the nitro group in 7c were seen at 1522 and
1345 cmꢀ1
groups should be free for antibacterial activity [24]. According to
our studies, implication of the NH2 group in the azomethine
function (6d, e) increases the antibacterial activity: 6d showed
.
In the 1H NMR spectra of compounds 4a–c and 7a–f, the pN–
CH2–No protons resonated as singlet at w5.15 and 5.05 ppm,
respectively, integrating for two protons. The –CH2–O–CH2–
protons of the morpholine residue appeared as a broad triplet at
3.68 ppm (J ¼ 4.8 Hz) in 4a–c and at 3.50 ppm (J ¼ 4.4 Hz) in 7a–f,
while the –CH2–N–CH2– protons of the morpholine residue reso-
nated as a triplet at 2.80 ppm (J ¼ 4.8 Hz) and 2.63–2.70 ppm
(J ¼ 4.3 Hz), respectively. The propyl protons of the 4a–c appeared
excellent activity against B. subtilis (MIC ¼ 64
showed good activity against A. baumanii and P. aeruginosa
g/mL respectively), comparative with triazole
mg/mL) and 6e
(MIC ¼ 128 and 256
m
5a and chloramphenicol. In these cases the increased activity could
also be attributed to the presence of N(CH3)2 group and furyl ring,
respectively.
The compounds 7a–f carrying a morpholino-methyl moiety
exhibited varying degrees of inhibition against the tested
microorganisms.
as
w1.72 ppm (J ¼ 7.3 Hz) and a triplet at
integrating for seven protons.
The 13C NMR spectrum of Mannich bases (see Section 6) showed
signals at
¼ 169 and w148 ppm due to heterocyclic C(3) and C(5)
carbons; at
a
triplet at
d
¼ 4.04–4.08 ppm (J ¼ 7.3 Hz),
a sextet at
¼ 0.84 ppm (J ¼ 7.3 Hz),
d
d
5. Conclusions
d
d
¼ 69 ppm due pN–CH2–No in 4a–c and
d
¼ 163–
This study reports the successful synthesis and characterization
of new Mannich and Schiff bases of 4-substituted 1,2,4-triazole-3-
thiones bearing diphenylsulfone moiety. The antibacterial data
given for the compounds presented in this paper allowed us to
state that the (phenylsulfonyl)phenyl group bonded to a triazole
ring is not a main cause for the appearance of antibacterial activity.
Other incorporated fragments to the triazole nucleus could be
responsible for the variation of the antibacterial activity. Other
investigations are in progress for this class of heterocyclic
compounds.
165 ppm; 147–148 ppm and 73 ppm attributed to C(3), C(5) and
pN–CH2–No in 7a–f, respectively.
4.2. Antibacterial activity
The results of antibacterial screening of newly prepared
compounds 4a–c, 6a–f, 7a–f expressed as the MIC values,
comparative with the starting triazoles 3a–c, 5a,b and chloram-
phenicol, are summarized in Table 2.
The (4-X-phenylsulfonyl)phenyl moiety in all these derivatives
was not a very important factor for their antibacterial activity, since
both compounds with X ¼ H, or X ¼ halogen showed similar
activity. For the compounds incorporating propyl moiety in the 4-
position of triazole ring, derivatives 3a–c, the antibacterial activity
was diminished as compared to the corresponding derivatives 5a,
b possessing the more compact amino group in this position.
The transformation of 3a–c into Mannich bases 4a–c did not
exert any significant modification on the antibacterial activity of
the original compounds 3a–c.
6. Experimental protocols
6.1. Chemistry
Melting points were determined with Boetius apparatus and are
uncorrected. The IR spectra (in KBr pellets) were recorded on the
Vertex 70 Bruker apparatus. The NMR spectra were registered on
a Varian Gemini 300 BB apparatus working at 300 MHz for a 1H and
75 MHz for 13C using TMS as internal standard.
Moreover, it is partly in contradiction with the purpose of
Ghannoum and co-workers. considering that both NH2 and SH
6.1.1. 5-[4-(4-X-phenylsulfonyl)phenyl]-2-(morpholin-4-ylmethyl)-
4-(n-propyl)-2,4-dihydro-3H-1,2,4-triazol-3-thione 4a–c
1,2,4-Triazole 4a–c (5 mmol) dissolved in methanol (20 mL)
were treated with morpholine (6 mmol) and then with 37% form-
aldehyde (10 mmol). The mixture was refluxed for 2 h. After cooling
with ice, the precipitates were filtered and purified by recrystalli-
zation from ethanol.
Table 2
Antibacterial activities of compounds 3(a–c)–7(a–f) as MIC values (
m
g/mL)
Gram-positive bacteriab
Ef Sa Se
>1024 >1024 >1024 >1024
Compound
X
Gram-negative bacteriaa
Ab
Cf
Pa
Bs
6.1.1.1. Compound 4a. IR (KBr, cmꢀ1): 3063, 3039 (aromatic C–H);
2978, 2931, 2873, 2834 (CH2, CH3); 1580, 1490, 1446
(C]N þ C]Caryl); 1315, 1282, 1154 (SO2); 1247 (C]S); 1197 (N–
3a
3b
3c
4a
4b
4c
5a
5b
6a
6b
6c
6d
6e
6f
7a
7b
7c
7d
7e
H
>1024
>1024
512
256
512
256
256
>1024
1024
–
–
–
–
–
–
>1024
–
–
–
>1024
–
128
>1024
–
–
>1024
>1024
>1024
>1024
–
1024
512
512
>1024
256
512
Cl >1024
Br
H
Cl >1024
Br >1024
>1024
>1024
1024
1024
512
>1024
–
–
–
–
–
512
256
–
–
1024
1024
1024
>1024
–
–
–
>1024 >1024
–
–
CH2–N); 1108 (CH2–O–CH2); 1009 (N–N); 1H NMR (CDCl3),
d: 7.72
>1024
>1024
1024
1024
–
(d, 2H, J ¼ 8.4 Hz, aromatic protons); 8.09 (d, 2H, J ¼ 8.4 Hz,
aromatic protons); 7.97 (dd, 2H, J ¼ 8.4; 1.5, aromatic protons); 7.54
(t, 2H, J ¼ 8.4 Hz, aromatic protons); 7.61 (tt, 1H, J ¼ 8.4; 1.5,
aromatic proton); 4.04 (wt, 2H, J ¼ 7.3 Hz, –CH2–CH2–CH3); 1.72 (sx,
2H, J ¼ 7.3 Hz, –CH2–CH2–CH3); 0.84 (t, 3H, J ¼ 7.3 Hz, –CH2–CH2–
CH3); 5.15 (s; 2H, N–CH2–N); 2.80 (wt, 4H, J ¼ 4.7 Hz, morpholine
residue); 3.66 (wt, J ¼ 4.7 Hz, morpholine residue); 13C NMR
H
Cl
H
H
H
H
H
Cl
H
H
H
H
H
Cl
512
128
>1024
256
1024
512
128
512
>1024
512
512
1024
512
512
1024
512 >1024
128
256
1024
512
1024
512
512
512
1024
512
1024
64
128
512
–
–
–
–
128
512
64
–
–
–
1024
–
(CDCl3), d: 169.48 (C]S), 148.54 (C5-triazolic ring), 144.00, 140.59,
>1024
>1024
1024
>1024
512
1024
>1024
1024
>1024
512
512
64
–
–
–
–
–
–
512
512
1024
512
1024
–
133.21, 130.52, 129.89, 128.96, 128.87, 127.52, (aromatic ring), 47.12,
21.62, 10.41 (propyl group); 69.62 (N–CH2–N), 66.76, 50.69 (mor-
pholine residue).
7f
Control
1024
128
1024
64
6.1.1.2. Compound 4b. IR (KBr, cmꢀ1): 3089 (aromatic C–H); 2952,
2935, 2857, 2831 (CH2, CH3); 1581, 1475, 1434 (C]N þ C]Caryl);
1321, 1288, 1163 (SO2); 1243 (C]S); 1199 (N–CH2–N); 1108 (CH2–
64
64
Note: Control ¼ chloramphenicol; – ¼ no inhibition action.
a
Ab (Acinetobacter baumanii ATCC 19606); Cf (Citrobacter freundii ATCC 8090); Pa
(Pseudomonas aeruginosa ATCC 9027).
O–CH2); 1006 (N–N); 762 (C–Cl); 1H NMR (CDCl3),
d: 7.72 (d, 2H,
b
J ¼ 8.6 Hz, aromatic protons); 8.09 (d, 2H, J ¼ 8.6 Hz, aromatic
Ef (Enterococcus faecalis ATCC 19433); Sa (Staphylococcus aureus ATCC 12600); Se
(Staphylococcus epidermidis ATCC 14990); Bs (Bacillus subtilis ATCC 6633).
protons); 7.92 (d, 2H, J ¼ 8.8, aromatic protons); 7.51 (d, 2H,

G.L. Almajan et al. / European Journal of Medicinal Chemistry 44 (2009) 3083–3089
3087
J ¼ 8.8 Hz, aromatic protons); 4.08 (wt, 2H, J ¼ 7.3 Hz, –CH2–CH2–
CH3); 1.71 (sx, 2H, J ¼ 7.3 Hz, –CH2–CH2–CH3); 0.85 (t, 3H, J ¼ 7.3 Hz,
–CH2–CH2–CH3); 5.16 (s; 2H, N–CH2–N); 2.81 (wt, 4H, J ¼ 4.8 Hz,
morpholine residue); 3.68 (wt, 4H, J ¼ 4.8 Hz, morpholine residue);
proton); 10.04 (s, 1H, CH]N), 8.83 (t, 1H, J ¼ 8.1 Hz, aromatic
proton), 8.63 (t, 1H, J ¼ 8.1 Hz, aromatic proton), 8.33 (t, 1H,
J ¼ 8.1 Hz, aromatic proton), 8.27 (t,1H, J ¼ 8.1 Hz, aromatic proton);
13C NMR (DMSO-d6),
d: 162.81 (C]S), 148.34 (C5-triazole ring),
13C NMR (CDCl3),
d: 169.60 (C]S), 148.46 (C5-triazolic ring), 143.61,
159.03 (CH]N), 147.32, 142.68, 140.65, 140.48, 134.51, 134.06,
130.98, 129.89, 129.55, 129.10, 127.80, 127.63, 123.19 (aromatic
rings).
140.59, 139.16, 130.86, 129.87, 129.46, 129.33, 128.44 (aromatic
ring), 47.18, 21.68, 10.88 (propyl group); 69.70 (N–CH2–N), 66.82,
50.74 (morpholine residue).
6.1.2.4. Compound 6d. IR (KBr, cmꢀ1): 3284 (NH), 3089 (aromatic
C–H), 2993, 2810 (CH3), 1603 (CH]N), 1586, 1528, 1474
(C]N þ C]Caryl), 1289, 1155 (SO2), 1245 (C]S), 1007 (N–N); 1H
6.1.1.3. Compound 4c. IR (KBr, cmꢀ1): 3083 (aromatic C–H); 2952,
2936, 2857, 2831 (CH2, CH3); 1572, 1470, 1434 (C]N þ C]Caryl);
1322, 1289, 1162 (SO2); 1243 (C]S); 1220 (N–CH2–N); 1106 (CH2–
NMR (DMSO-d6),
d
: 8.09 (d, 2H, J ¼ 8.4 Hz, aromatic protons); 8.14
O–CH2); 1007 (N–N); 573 (C–Br); 1H NMR (CDCl3),
d: 7.74 (d, 2H,
(d, 2H, J ¼ 8.4 Hz, aromatic protons), 7.98 (wd, 2H, J ¼ 7.8 Hz,
aromatic protons), 7.62–7.70 (m, 3H, aromatic protons), 9.21 (s, 1H,
CH]N), 7.69 (d, 2H, J ¼ 8.9 Hz, aromatic protons), 6.80 (d, 2H,
J ¼ 8.9 Hz, aromatic protons), 3.02 (s, 6H, CH3); 13C NMR (DMSO-d6),
J ¼ 8.7 Hz, aromatic protons); 8.07 (d, 2H, J ¼ 8.7 Hz, aromatic
protons); 7.82 (d, 2H, J ¼ 8.6, aromatic protons); 7.67 (d, 2H,
J ¼ 8.6 Hz, aromatic protons); 4.04 (wt, 2H, J ¼ 7.4 Hz, –CH2–CH2–
CH3); 1.71 (sx, 2H, J ¼ 7.4 Hz, –CH2–CH2–CH3); 0.84 (t, 3H, J ¼ 7.4 Hz,
–CH2–CH2–CH3); 5.15 (s; 2H, N–CH2–N); 2.81 (wt, 4H, J ¼ 4.8 Hz,
morpholine residue); 3.68 (wt, 4H, J ¼ 4.8 Hz, morpholine residue);
d: 162.91 (C]S), 146.76 (C5-triazole ring), 153.43 (CH]N), 146.75,
142.40, 140.55, 134.04, 130.72, 130.40, 129.90, 129.15, 127.75, 127.54,
118.31, 111.64, (aromatic rings), 25.26 (CH3).
13C NMR (CDCl3),
d: 169.55 (C]S), 148.42 (C5-triazolic ring), 143.51,
139.65, 132.82, 130.83, 129.43, 129.32, 129.13, 128.39 (aromatic
ring), 47.15, 21.65, 11.21 (propyl group); 69.65 (N–CH2–N), 66.77,
50.70 (morpholine residue).
6.1.2.5. Compound 6e. IR (KBr, cmꢀ1): 3095 (aromatic C–H), 2632
(SH), 1608 (CH]N), 1539, 1472 (C]N þ C]Caryl), 1285, 1155 (SO2),
1017 (N–N), 1104 (C–O–C furyl); 1H NMR (DMSO-d6),
d: 8.09 (s, 4H,
aromatic protons); 8.00 (dd, 2H, J ¼ 7.1; 1.7 Hz, aromatic protons);
7.63 (t, 2H, J ¼ 7.1 Hz, aromatic protons), 7.71 (tt, 1H, J ¼ 7.1; 1.7,
aromatic proton), 9.61 (s, 1H, CH]N), 8.06 (wd, 1H, J ¼ 1.8 Hz,
aromatic proton), 6.78 (dd, 1H, J ¼ 3.5, 1.8 Hz, aromatic proton), 7.40
6.1.2. 4-(Substituted-arylidene)amino-5-[4-(4-X-
phenylsulfonyl)phenyl]-2,4-dihydro-3H-1,2,4-triazole-3-thiones
6a–f
To the solution of 1,2,4-triazole 5 (10 mmol) in glacial acetic acid
(15 mL) an equimolar amount of aromatic aldehyde was added. The
obtained suspension was heated until a clear solution was obtained.
Then the formed mixture was stirred at room temperature over-
night. The precipitated solid obtained after the elimination of
glacial acetic acid was washed with cold water and recrystallized
from a mixture of ethanol and dioxane (2:1, v/v).
(wd, 1H, J ¼ 3.5 Hz, aromatic proton); 13C NMR (DMSO-d6),
d:
162.68 (C]S), 148.38 (C5-triazole ring), 154.46 (CH]N), 142.59,
140.51, 134.05, 130.13, 129.90, 129.45, 127.75, 127.57 (aromatic
rings), 147.17, 146.62, 120.70, 113.15 (furyl ring).
6.1.2.6. Compound 6f. IR (KBr, cmꢀ1): 3289, 2740 (NH), 3099
(aromatic C–H), 1603 (CH]N), 1573, 1539, 1499 (C]N þ C]Caryl),
1318, 1157 (SO2), 1222 (C]S), 1016 (N–N), 764 (C–Cl); 1H NMR
6.1.2.1. Compound 6a. IR (KBr, cmꢀ1): 3280, 2746 (NH), 3067
(aromatic C–H), 1602 (CH]N), 1573, 1539, 1499 (C]N þ C]Caryl),
(DMSO-d6),
d
: 8.10 (d, 2H, J ¼ 8.8 Hz, aromatic protons); 8.14 (d, 2H,
J ¼ 8.8 Hz, aromatic protons); 7.98 (d, 2H, J ¼ 8.7 Hz, aromatic
protons), 7.67 (d, 2H, J ¼ 8.7 Hz, aromatic protons), 9.71 (s, 1H,
CH]N); 7.88 (dd, 2H, J ¼ 7.8, 1.1 Hz, aromatic protons); 7.55 (t, 2H,
J ¼ 7.8 Hz, aromatic protons); 7.63 (wt, 1H, J ¼ 7.8 Hz, aromatic
1318, 1157 (SO2), 1222 (C]S), 1016 (N–N); 1H NMR (DMSO-d6),
d:
8.02 (d, 2H, J ¼ 8.8 Hz, aromatic protons); 8.17 (d, 2H, J ¼ 8.8 Hz,
aromatic protons); 7.96 (dd, 2H, J ¼ 8.4; 1.5 Hz, aromatic protons),
7.48–7.63 (m, 6H, aromatic protons), 7.86 (dd, 2H, J ¼ 8.5; 1.6 Hz,
protons); 13C NMR (DMSO-d6),
d: 162.90 (C]S), 147.18 (C5-triazole
aromatic protons); 10.16 (s, 1H, CH]N); 13C NMR (DMSO-d6),
d:
ring), 153.77 (CH]N), 142.21, 139.38, 133.14, 131.86, 131.83, 130.40,
163.40 (C]S), 147.21 (C5-triazole ring), 159.10 (CH]N), 142.61,
140.59, 133.24, 131.86, 131.82, 130.10, 129.12, 129.10, 128.86, 128.74,
128.52, 127.35 (aromatic rings).
130.14, 129.64, 129.52, 129.38, 128.99, 127.95 (aromatic rings).
6.1.3. 4-(Substituted-arylidene)amino-5-[4-(4-X-
phenylsulfonyl)phenyl]-2-(morpholin-4-yl methyl)-2,4-dihydro-3H-
1,2,4-triazole-3-thione 7a–f
6.1.2.2. Compound 6b. IR (KBr, cmꢀ1): 3285, 2743 (NH), 3065
(aromatic C–H), 2911, 2823 (CH3), 1600 (CH]N), 1596, 1541, 1475
(C]N þ C]Caryl), 1292, 1155 (SO2), 1257, 1021 (Caryl–OCH3), 1225
The Schiff bases 6a–c (5 mmol) were dissolved in a mixture of
ethanol and dioxane (2:1, v/v). Then formaldehyde (37%, 1.5 mL)
and morpholine (5 mmol) in ethanol were added to this solution.
The mixture was stirred for 3–4 h and kept overnight at room
temperature. The separated solid was collected by filtration and
recrystallized from a mixture of ethanol and dioxane (2:1, v/v) to
yield the compounds 7a–f.
(C]S), 1012 (N–N); 1H NMR (DMSO-d6),
d: 8.07 (d, 2H, J ¼ 8.1 Hz,
aromatic protons); 8.13 (d, 2H, J ¼ 8.1 Hz, aromatic protons); 7.96
(dd, 2H, J ¼ 8.1; 1.4 Hz, aromatic protons), 7.60–7.70 (m, 5H,
aromatic protons), 7.19 (wd, 1H, J ¼ 8.4 Hz, aromatic proton); 7.07
(wt, 1H, J ¼ 8.4 Hz, aromatic proton); 10.03 (s, 1H, CH]N), 3.87 (s,
3H, CH3); 13C NMR (DMSO-d6),
d: 162.64 (C]S), 147.22 (C5-triazole
ring), 159.44 (CH]N), 161.90, 142.49, 140.53, 134.83, 134.13, 130.26,
129.88, 129.45, 127.70, 127.53, 121.05, 119.92, 112.39 (aromatic
rings), 56.06 (CH3).
6.1.3.1. Compound 7a. IR (KBr, cmꢀ1): 3089 (aromatic C–H), 2938,
2842 (CH2, CH3), 1605 (CH]N), 1583, 1499, 1477 (C]N þ C]Caryl),
1293, 1158 (SO2), 1225 (C]S), 1175 (N–CH2–N); 1088 (CH2–O–CH2);
1012 (N–N); 1H NMR (CDCl3),
d
: 8.05 (d, 2H, J ¼ 8.5 Hz, aromatic
6.1.2.3. Compound 6c. IR (KBr, cmꢀ1): 3305, 2796 (NH), 3095
(aromatic C–H), 1611 (CH]N), 1476, 1430 (C]N þ C]Caryl), 1529,
1350 (NO2), 1291, 1153 (SO2), 1231 (C]S), 1025 (N–N); 1H NMR
protons); 8.14 (d, 2H, J ¼ 8.5 Hz, aromatic protons); 8.00 (dd, 2H,
J ¼ 8.4; 1.5 Hz, aromatic protons); 7.58–7.70 (m, 3H, aromatic
protons); 8.09 (d, 2H, J ¼ 8.3; 1.6 Hz, aromatic protons); 7.41 (t, 2H,
J ¼ 8.3 Hz, aromatic protons); 7.62 (t, 1H, J ¼ 8.3 Hz, aromatic
proton); 10.10 (s, 1H, CH]N); 5.04 (s, 2H, N–CH2–N); 2.68 (t, 4H,
J ¼ 4.5 Hz, morpholine residue); 3.52 (t, J ¼ 4.5 Hz, morpholine
(DMSO-d6),
d
: 8.09 (d, 2H, J ¼ 8.1 Hz, aromatic protons); 8.10 (d, 2H,
J ¼ 8.1 Hz, aromatic protons); 7.98 (dd, 2H, J ¼ 7.9; 1.5 Hz, aromatic
protons), 7.62–7.70 (m, 3H, aromatic protons), 7.19 (wd, 1H,
J ¼ 8.4 Hz, aromatic proton); 7.07 (wt, 1H, J ¼ 8.4 Hz, aromatic
residue); 13C NMR (CDCl3),
d: 165.08 (C]S), 147.21 (C5-triazole

3088
G.L. Almajan et al. / European Journal of Medicinal Chemistry 44 (2009) 3083–3089
ring); 154.17 (CH]N); 142.56, 140.98, 134.94, 133.34, 131.78, 130.13,
129.60, 128.95, 128.52, 127.97, 127.65, 125.93 (aromatic rings); 73.74
(N–CH2–N), 66.80, 50.70 (morpholine residue).
rings); 146.16, 142.33, 120.51, 112.33 (furyl ring); 73.12 (N–CH2–N),
66.78, 50.74 (morpholine residue).
6.1.3.6. Compound7f. IR (KBr, cmꢀ1): 3099 (aromatic C–H), 2989,
2924, 2878, 2835 (CH2, CH3), 1603 (CH]N), 1573, 1539, 1499
(C]N þ C]Caryl), 1318, 1157 (SO2), 1222 (C]S), 1186 (N–CH2–N);
6.1.3.2. Compound 7b. IR (KBr, cmꢀ1): 3089 (aromatic C–H), 2939,
2857 (CH2, CH3), 1605 (CH]N), 1583, 1499, 1477 (C]N þ C]Caryl),
1328, 1158 (SO2), 1228 (C]S), 1186 (N–CH2–N); 1088 (CH2–O–CH2);
1071 (CH2–O–CH2); 1016 (N–N); 1H NMR (CDCl3),
d: 8.08 (d, 2H,
1012 (N–N); 1257, 1022 (Carom–OCH3); 1H NMR (CDCl3),
d: 8.08 (d,
J ¼ 8.5 Hz, aromatic protons); 8.12 (d, 2H, J ¼ 8.5 Hz, aromatic
protons); 7.98 (d, 2H, J ¼ 8.1 Hz, aromatic protons); 7.70 (d, 2H,
J ¼ 8.1 Hz, aromatic protons); 8.05 (dd, 2H, J ¼ 8.2 Hz, aromatic
protons); 7.58 (t, 2H, J ¼ 8.2 Hz, aromatic protons); 7.62 (t, 1H,
J ¼ 8.2 Hz, aromatic proton); 10.10 (s, 1H, CH]N); 5.04 (s, 2H, N–
CH2–N); 2.69 (t, 4H, J ¼ 4.4 Hz, morpholine residue); 3.52 (t,
2H, J ¼ 8.3 Hz, aromatic protons); 8.14 (d, 2H, J ¼ 8.3 Hz, aromatic
protons); 7.95 (dd, 2H, J ¼ 8.1; 1.4 Hz, aromatic protons); 7.50 (t, 2H,
J ¼ 8.1 Hz, aromatic protons); 7.57 (tt, 1H, J ¼ 8.1; 1.4 Hz, aromatic
proton); 8.10 (d, 1H, J ¼ 8.3 Hz, aromatic proton); 7.53 (d, 1H,
J ¼ 8.3 Hz, aromatic proton); 7.11 (tt, 1H, J ¼ 8.3; 1.1 Hz, aromatic
protons); 6.90 (d, 1H, J ¼ 8.3 Hz, aromatic proton); 10.08 (s, 1H,
CH]N); 5.06 (s, 2H, N–CH2–N); 2.65 (t, 4H, J ¼ 4.5 Hz, morpholine
residue); 3.50 (wt, 4H, J ¼ 4.5 Hz, morpholine residue); 3.85 (s, 3H,
J ¼ 4.4 Hz, morpholine residue); 13C NMR (CDCl3),
d: 165.86 (C]S),
148.09 (C5-triazole ring); 152.98 (CH]N); 142.50, 140.34, 139.60,
134.94, 132.04, 130.33, 129.68, 129.52, 128.99, 128.70, 127.97, 125.50
(aromatic rings); 73.65 (N–CH2–N), 66.82, 50.68 (morpholine
residue).
OCH3); 13C NMR (CDCl3),
d: 164.10 (C]S), 147.42 (C5-triazole ring);
156.28 (CH]N); 159.41, 142.10, 140.53, 133.61, 133.14, 132.95,
130.01, 129.89, 129.45, 127.71, 127.58, 120.33, 118.31, 114.25
(aromatic rings); 73.50 (N–CH2–N), 66.71, 50.78 (morpholine
residue).
6.2. Antibacterial activity
Qualitative determination of antimicrobial activity was done
using the disk diffusion method. Suspensions in sterile peptone
water from 24 h cultures of microorganisms were adjusted to
0.5 McFarland. Muller–Hinton Petri dishes of 90 mm were inocu-
lated using these suspensions. Paper disks (6 mm in diameter)
6.1.3.3. Compound 7c. IR (KBr, cmꢀ1): 3090 (aromatic C–H), 2939,
2848 (CH2, CH3), 1606 (CH]N), 1596, 1572, 1475 (C]N þ C]Caryl),
1291, 1157 (SO2), 1230 (C]S), 1175 (N–CH2–N); 1068 (CH2–O–CH2);
1009 (N–N); 1522, 1345 (NO2); 1H NMR (CDCl3),
d: 8.09 (d, 2H,
J ¼ 8.1 Hz, aromatic protons); 8.12 (d, 2H, J ¼ 8.1 Hz, aromatic
protons); 7.96 (wd, 2H, J ¼ 7.9 Hz, aromatic protons); 7.62–7.70 (m,
3H, aromatic protons); 8.80 (t, 1H, J ¼ 8.1 Hz, aromatic proton); 8.65
(d, 1H, J ¼ 8.1 Hz, aromatic proton); 8.45 (d, 1H, J ¼ 8.1 Hz, aromatic
proton); 7.95 (t, 1H, J ¼ 8.1 Hz, aromatic proton); 10.05 (s, 1H,
CH]N); 5.06 (s, 2H, N–CH2–N); 2.63 (t, 4H, J ¼ 4.4 Hz, morpholine
residue); 3.52 (wt, 4H, J ¼ 4.4 Hz, morpholine residue); 13C NMR
containing 10
mL of the substance to be tested (at a concentration of
2048 g/mL in DMSO) were placed in a circular pattern in each
m
inoculated plate. Incubation of the plates was done at 37 ꢁC for 18–
24 h. Reading of the results was done by measuring the diameters
of the inhibition zones generated by the tested substances using
a ruler. Chloramphenicol was used as a reference substance.
Determination of MIC was done using the serial dilutions in
liquid broth method. The materials used were 96-well plates,
suspensions of microorganism (0.5 McFarland), Muller–Hinton
(CDCl3), d: 163.86 (C]S), 148.19 (C5-triazole ring); 158.17 (CH]N);
147.80, 142.08, 140.12, 138.48, 134.10,131.46, 130.23, 129.90, 129.75,
129.65, 127.75, 127.60, 125.53, 121.79 (aromatic rings); 73.98 (N–
CH2–N), 66.48, 50.82 (morpholine residue).
broth (Merck), solutions of the substances to be tested (2048 mg/mL
in DMSO). The following concentrations of the substances to be
tested were obtained in the 96-well plates: 1024, 512, 256, 128, 64,
32, 16, 8, 4, 2 m
g/mL. After incubation at 37 ꢁC for 18–24 h, the MIC
for each tested substance was determined by macroscopic obser-
vation of microbial growth. It corresponds to the well with the
lowest concentration of the tested substance where microbial
growth was clearly inhibited.
6.1.3.4. Compound 7d. IR (KBr, cmꢀ1): 3089 (aromatic C–H), 2935,
2853 (CH2, CH3), 1603 (CH]N), 1596, 1526, 1477 (C]N þ C]Caryl),
1292, 1159 (SO2), 1248 (C]S), 1179 (N–CH2–N); 1088 (CH2–O–CH2);
1012 (N–N); 1257, 1022 (Carom–OCH3); 1H NMR (CDCl3),
d: 8.10 (d,
2H, J ¼ 8.1 Hz, aromatic protons); 8.18 (d, 2H, J ¼ 8.1 Hz, aromatic
protons); 7.98 (wd, 2H, J ¼ 7.8 Hz, aromatic proton); 7.48 (t, 2H,
J ¼ 7.8 Hz, aromatic protons); 7.68 (tt, 1H, J ¼ 7.8 Hz, aromatic
proton); 7.80 (d, 2H, J ¼ 8.6 Hz, aromatic proton); 6.74 (d, 2H,
J ¼ 8.6 Hz, aromatic proton); 9.50 (s, 1H, CH]N); 5.06 (s, 2H, N–
CH2–N); 2.64 (t, 4H, J ¼ 4.3 Hz, morpholine residue); 3.50 (t, 4H,
J ¼ 4.3 Hz, morpholine residue); 2.90 (s, 6H, CH3); 13C NMR (CDCl3),
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