Synthesis, structure and investigations of tuberculosis inhibition activities of new 4-methyl-1-substituted-1H-1,2,4-triazole-5(4H)-thione

Article abstract of DOI:10.1002/jhet.5570450655

(Chemical Equation Presented) By the reaction aminomethylation, chloromethylation and acylation of 4-methyl-4H-1,2,4-triazole-3-thiol, 4-methyl-1-substituted-1H-1,2,4-triazole-5(4H)-thione 1-8 were obtained. Molecular structure of the obtained compounds w

Full text of DOI:10.1002/jhet.5570450655

Nov-Dec 2008
1893
Synthesis, Structure and Investigations of
Tuberculosis Inhibition Activities of New 4-Methyl-
1-substituted-1H-1,2,4-triazole-5(4H)-thione
Monika Wujec1*, Marta Swatko-Ossor2, Liliana Mazur3, Zofia Rzaczynska3
and Agata Siwek1
1Department of Organic Chemistry, Faculty of Pharmacy, Medical University, Staszica 6, 20-081 Lublin,
Poland;+48815357373, e-mail:* monika.wujec@am.lublin.pl
2Department of Biochemistry, Medical University, Chodzki 1, Lublin, Poland;
e-mail:marta.swatko@am.lublin.pl
3Department of General and Coordination Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska
University, 20-031 Lublin, Poland; e-mail: lmazur2@op.pl
Received April 30, 2008
HCHO + amine or
HCHO + HCl or
(CH3CO)O
N
N
N N R
SH
S
N
N
CH3
CH3
By the reaction aminomethylation, chloromethylation and acylation of 4-methyl-4H-1,2,4-triazole-3-
thiol, 4-methyl-1-substituted-1H-1,2,4-triazole-5(4H)-thione 1-8 were obtained. Molecular structure of the
obtained compounds was confirmed by an elemental analysis, IR, 1H NMR and 13C NMR spectra and
additionally by X-ray analysis for 2. Six new compounds 1, 2, 4-7 were tested for antibacterial activity
against Mycobacterium smegmatis, Mycobacterium phlei and avirulent strain Mycobacterium H37Ra.
J. Heterocyclic Chem., 45, 1893 (2008).
Scheme 1
Thiol/thione tautomerism forms of 4-methyl-4H-1,2,4-triazole-3-thiol.
INTRODUCTION
Tuberculosis (TB) has again become epidemic in many
parts of the world. The increase in TB and other non-
specific mycobacterial infections is associated with HIV,
homelessness, drug abuse and immigration of persons
with active infections. Another serious problem is the
emergence of multidrug-resistant TB. Therefore new
antituberculotic drugs and/or new derivatives of old drugs
have been prepared and studied. A special interest has
been focussed on five membered heterocyclic compounds
used very often in the pharmacological and medicinal
applications. The anti-tuberculosis activity of pyrrole [1-
3], oxadiazole [4], imidazole [5], triazole [6-9] and other
heterocyclic systems derivatives has been reported.
In this paper, we present the synthesis, structure and
anti-tuberculosis activity of new 4-methyl-1-substituted-1-
H-1,2,4-triazole-5(4H)-thione.
N
N
N NH
SH
S
N
N
CH3
CH3
Scheme 2
Synthesis 4-methyl-1-substituted-1H-1,2,4-triazole-5(4H)-thione.
HCHO + amine or
HCHO + HCl or
(CH3CO)O
N
N
N N R
SH
S
N
N
CH3
CH3
Table 1
Substituents of compounds 1-8.
Compounds
No
R
4-Methyl-4H-1,2,4-triazole-3-thiol is a starting material
for the synthesis of new derivatives. This compound can
exist in two tautomeric forms as shown in Scheme 1.
In various reactions this compound can give both S- or
N-derivatives. In the previous paper S-derivatives were
obtained, by the reaction with bromoacetate ester [10]. In
this work 4-methyl-4H-1,2,4-triazole-3-thiol was subjected
to following reactions: aminomethylation, chloromethyl-
ation and acylation (Scheme 2). Mechanism of this
reaction have been reported earlier [11]. Some of the
obtained compounds 1, 2, 4-7 were tested for anti-
tuberculosis activity.
Br
NH CH2
1
2
O
N
CH2
N CH2
3
4
N
N
CH2
F
5
N
N
CH2

1894
M. Wujec, M. Swatko-Ossor, L. Mazur, Z. Rzaczynska and A. Siwek
Vol 45
Table 1 (continued)
Compounds
No
R
F
N
N CH2
6
7
8
CH2Cl
COCH3
RESULTS AND DISCUSSION
The aminomethylation reactions were carried out in
ethanolic solution with an equivalent amount of formalin
by using 4-bromoaniline, morpholine, pyrrolidine,
N-phenylpiperazine, 1-(2-fluorophenyl) piperazine, and
1-(4-fluorophenyl) piperazine as shown in the Scheme 2.
The conditions of the reactions were established
experimentally.
Figure 1. A view of the asymmetric unit of 2, showing the atomic
numbering scheme. Displacement ellipsoids are drawn at the 50%
probability level. Dashed lines indicate hydrogen bonds.
The obtained products were characterized by their
1
elemental analysis, IR, H NMR and 13C NMR spectra.
The signal of proton characteristic for the –NH-C=S
group, found in the substrate, was not observed in the H
Selected bond distances are shown in Table 3.
1
NMR spectra of new compounds.
Table 3
Among the six tested compounds two of them (2,7)
showed inhibitory activity from low to moderate.
Compound 7 with chloromethyl group in position 1
showed the highest activity from all tested compounds
with MIC = 128 mg/L against Mycobacterium phlei.
Moreover 4-methyl-1-[1-(morpholin)methyl]-1H-1,2,4-
triazole-5(4H)-thione (2) affected the growth of
Mycobacterium phlei with MIC = 256 mg/L (Table 2).
Selected bond lengths [Å] for 2.
N1ꢀN2
N2ꢀC3
C3ꢀN4
N4ꢀC5
N1ꢀC5
N4ꢀC4m
C5ꢀS1
N1ꢀC1
C1ꢀN1p
N1pꢀC2p
N1pꢀC6p
O4pꢀC3p
O4pꢀC5p
1.377(3)
1.282(3)
1.350(4)
1.366(3)
1.348(3)
1.456(3)
1.665(3)
1.472(3)
1.427(3)
1.457(3)
1.453(3)
1.406(4)
1.409(3)
N11ꢀN12
N12ꢀC13
C13ꢀN14
N14ꢀC15
N11ꢀC15
N14ꢀC14m
C15ꢀS2
N11ꢀC11
C11ꢀN11p
N11pꢀC12p
N11pꢀC16p
O14pꢀC13p
O14pꢀC15p
1.377(3)
1.280(3)
1.348(4)
1.365(3)
1.348(3)
1.447(4)
1.665(3)
1.469(3)
1.430(3)
1.458(3)
1.453(3)
1.411(3)
1.418(3)
Table 2
MICs and MBCs of the tested compounds.
MIC(mg/L)
MBC (mg/L)
Compound
No
M.
phlei
16
M.
37 Ra
16
M.
Equivalent bond distances and angles for both
molecules are equal within the experimental error, but
they have different hydrogen-bonding patterns. The 1,2,4-
triazole-5-thione system is planar in both molecules with
deviations of S1 and S2 atoms from heterocyclic ring
planes of 0.025(5) and 0.045(4) Å. At the same time the
methyl C4m and C14m atoms are displaced out of the
triazole rings by respectively 0.023(5) and 0.035(6) Å.
The bond distances within the five-membered
heterocyclic rings are not regular. The N2=C3 and
N12=C13 distances (1.282(3) and 1.280(3) Å) are of
double-bond character, whereas the remaining CꢀN and
NꢀN endocyclic bonds have an intermediate character
(Table 2), indicating delocalization of the electron cloud.
The C5=S1 and C15=S2 distances are in accordance with
values observed in other 1,2,4-triazole-5-thione systems
[12]. The morpholine ring in both molecules exists in a
chair conformation. The bond lengths observed within the
six-membered systems are comparable with those
reported for molecules of free morpholine [13]. The
relative orientation of morpholine and triazole rings could
H
smegmatis
128
256
Rifampicin
32
32
2
7
512
1024
128
256
512
1024
256
256
512
256
512
512
In conclusion, eight new 4-methyl-1-subtituted-1H-
1,2,4-triazole-5(4H)-thione, with different substituents at
the 1- position were synthesized. The synthesis showed an
excellent average yield of over 87%, making these
compounds readily available. Among tested compounds
only triazoles with chloromethyl and morpholinemethyl
group showed moderate antimicrobial activity against
Mycobacterium spp. and can be consider for further
microbiological tests.
X-ray Crystallography. The molecular structure of 2
was confirmed by X-ray analysis. Triclinic crystals of 2
are built up of two (A and B) symmetrically independent
molecules. Numbering scheme and structural view with
displacement parameters of molecules are shown in Fig. 1.

Nov-Dec 2008
Synthesis and Tuberculosis Inhibition of some new 1,2,4-Triazoles
1895
4-Methyl-1-(pyrrolidin-1-ylmethyl]-1H-1,2,4-triazole-5(4H)-
thione (3). Yield 1.71g (86 %). M.p. 89–91°C. For C8H14N4S
(198.3) calculated: 48.46% C, 7.12% H, 28.26% N; found:
48.50% C, 7.08% H, 28.20% N. IR (KBr): 3024 (CHal), 1620
be described by for instance torsion angles
N2ꢀN1ꢀC1ꢀN1p/N12ꢀN11ꢀC11ꢀN11p; their values
(±89.4(3)°) indicate ±sc conformation. The bent
conformation adopted by molecules of 2 in the solid state
is additionally stabilized by weak C2pꢀH2p1…N2/
C12pꢀH12b…N12 intramolecular hydrogen bonds. In
crystals of 2 the packing of molecules is stabilized by
different weak intermolecular interactions (Table 4).
1
(C=N), 1545 (C–N), 1358 (C=S). H NMR (DMSO-d6): 1.60,
1.61, 1.62 (t, J = 3.5 Hz, 4H, 2xCH2), 2.72, 2.73, 2.74 (t, J = 2.4
Hz, 4H, 2xCH2) 3.47 (s, 3H, CH3), 5.07 (s, 2H, CH2), 8.49 (s,
1H, CH). 13C NMR 23.4 (2xCH2), 32.1 (CH3), 49.4 (2xCH2),
64.6 (CH2), 141.1 (CH), 167.1 (C=S).
4-Methyl-1-((phenylpiperazin-1-yl)methyl)-1H-1,2,4-tria-
zole-5(4H)-thione (4). Yield 2.37g (82 %). M.p. 111–113°C.
For C14H19N5S (289.4) calculated: 58.10% C, 6.62% H, 24.20%
N; found: 58.02% C, 6.69% H, 24.10% N. IR (KBr): 3094
(CHar), 2980, 1421 (CHal), 1671 (C=N), 1501 (C–N), 1364
(C=S). H NMR (DMSO-d6): 2.77-2.80 (m, 4H, 2xCH2), 3.03-
3.12 (m, 4H, 2xCH2), 3.48 (s, 3H, CH3), 5.08 (s, 2H, CH2), 6.73-
7.29 (m, 5H, 5xCHar), 8.52 (s, 1H, CH).
Table 4.
Hydrogen-bonding geometry [Å, °] for 2.
DꢀH…A
DꢀH
0.97
0.97
0.97
1.022
0.99
0.96
H…A
2.803
2.830
2.742
2.811
2.859
2.535
D…A
<DHA
108
107
141
153
1
C2pꢀH2p1…N2
C12pꢀH12b…N12
C5pꢀH5p1…N12
C13ꢀH13…S1
C3ꢀH3…S2(i)
3.233(3)
3.244(3)
3.550(4)
3.750(4)
3.714(3)
3.378(4)
1-((4-(2-Fluorophenyl)piperazin-1-yl)methyl)-4-methyl-1H-
1,2,4-triazole-5(4H)-thione (5). Yield 2.43g (79 %). M.p. 115–
118°C. For C14H18FN5S (307.4) calculated: 54.70% C, 5.90% H,
22.78% N; found: 54.67% C, 5.83% H, 22.74% N. IR (KBr):
3102 (CHar), 2939, 1420 (CHal), 1607 (C=N), 1516 (C–N), 1377
145
147
C14mꢀH14c…O14p(ii)
Symmetry codes: (i) x, y+1, z-1; (ii) x, y+1, z
1
(C=S). H NMR (DMSO-d6): 2.77-2.80 (m, 4H, 2xCH2), 3.04-
EXPERIMENTAL
3.06 (m, 4H, 2xCH2), 3.49 (s, 3H, CH3), 5.06 (s, 2H, CH2), 6.84-
7.01 (m, 4H, 4xCHar), 8.52 (s, 1H, CH).
Chemistry. Melting points were determined in Fisher-Johns
blocs and presented without any corrections. IR spectra were
recorded in KBr using Specord IR-75 spectrophotometer. The
1H NMR and 13C NMR spectra were recorded on a Bruker
Avance 300 in DMSO-d6 with TMS as internal standard.
Chemicals were purchased from Lancaster or Merck Co. and
used without further purification. Purity was checked by TLC on
1-((4-(4-Fluorophenyl)piperazin-1-yl)methyl)-4-methyl-1H-
1,2,4-triazole-5(4H)-thione (6). Yield 2.67 g (87 %). M.p. 112–
113°C. For C14H18FN5S (307.4) calculated: 54.70% C, 5.90% H,
22.78% N; found: 54.69% C, 5.68% H, 22.70% N. IR (KBr):
3099 (CHar), 2978, 1420 (CHal), 1620 (C=N), 1526 (C–N), 1370
1
(C=S). H NMR (DMSO-d6): 2.68-2.83 (m, 4H, 2xCH2), 2.96-
2.99 (m, 4H, 2xCH2), 3.50 (s, 3H, CH3), 5.14 (s, 2H, CH2), 6.88-
7.21 (m, 4H, 4xCHar), 8.53 (s, 1H, CH). 13C NMR 32.2 (CH3),
49.1 (2xCH2), 49.7 (2xCH2), 68.4 (CH2), 115.3 (2xCHar), 117.3
(2xCHar), 141.5 (CH), 154.4, 157.6 (2xCar), 166.2 (C=S).
1-(Chloromethyl)-4-methyl-1H-1,2,4-triazole-5(4H)-thione
(7). 0.01 Mole of 4-methyl-4H-1,2,4-triazole-3-thiol, 0.8g (0.01
mole) of 37% formaldehyde aqueous solution and 0.02 mole
36% HCl were mixed. After 15 min the product was collected
by filtration, dried and crystallized from ethanol. This compoud
is known [14].
1-(4-Methyl-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-1-yl)-
ethanone (8). 4-Methyl-4H-1,2,4-triazole-3-thiol (0.01 mole)
and 5 mL acetic anhydride were refluxed for 3 h. After cooling
the precipitate was collected by filtration, dried and crystallized
from ethanol. Yield 1.41 g (90 %). M.p. 165–167°C. For
C5H7N3OS (157.2) calculated: 38.20% C, 4.49% H, 26.73% N;
found: 38.12% C, 4.49% H, 26.50% N. IR (KBr): 3080 (CHal),
Merck Co. plates Aluminium oxide 60 F254 in
CHCl3/C2H5OH(10:1) solvent system with UV visualization.
a
1-Aminomethyl-4-methyl-1H-1,2,4-triazole-5(4H)-thione
derivatives (1-6). 1.15 g (0.01 mole) of 4-methyl-4H-1,2,4-
triazole-3-thiol was dissolved in 10 mL ethanol. Then 0.8g (0.01
mole) of 37% formaldehyde aqueous solution and 0.02 mole
appropriate amine were added. The mixture was mixed carefully
and kept at room temperature for 24 h (for compound 6 - 10
min). Next, the precipitate was filtered off, dried and crystallized
from ethanol.
1-((4-Bromophenylamino)methyl)-4-methyl-1H-1,2,4-tri-
azole-5(4H)-thione (1). Yield 2.69g (90 %). M.p. 127–129°C.
For C10H11N4BrS (299.2) calculated: 40.14% C, 3.71% H,
18.73% N; found: 40.10% C, 3.69% H, 18.70% N. IR (KBr):
1
3300 (NH), 3120 (CHar), 2929, 1445 (CHal), 1370 (C=S). H
NMR (DMSO-d6): 3.46 (s, 3H, CH3), 5.41, 5.43 (d, J= 7.4 Hz,
2H, CH2), 6.84, 6.85, 6.87, 6.88 (dd, J = 2.15 Hz, J= 6.8 Hz,
2H, 2xCHar), 7.17 (s, 1H, NH), 7.21, 7.22, 7.23, 7.24 (dd, J =
2.08 Hz, J = 6.8 Hz, 2H, 2xCHar), 8.47 (s, 1H, CH). 13C NMR
32.0 (CH3), 56.6 (CH2), 108.0, 145.3 (2xCar), 115.1 (2xCHar),
131.4 (2xCHar), 141.5 (CH), 165.6 (C=S).
4-Methyl-1-(morpholinomethyl)-1H-1,2,4-triazole-5(4H)-
thione (2). Yield 1.91g (89 %). M.p. 116–118°C. For
C8H14N4OS (214.3) calculated: 44.84% C, 6.59% H, 26.15% N;
found: 44.72% C, 6.59% H, 26.20% N. IR (KBr): 3056 (CHal),
1630 (C=N), 1550 (C–N), 1379 (C=S), 1258 (C–O–C). 1H NMR
(DMSO-d6): 2.61, 2.63, 2.64 (t, J = 4.7 Hz, 4H, 2xCH2), 3.48 (s,
3H, CH3), 3.51, 3.53, 3.55 (t, J = 4.7 Hz, 4H, 2xCH2), 4.98 (s,
2H, CH2), 8.51 (s, 1H, CH). 13C NMR 32.2 (CH3), 50.2 (2xCH2),
66.0 (2xCH2), 68.7 (CH2), 141.3 (CH), 167.3 (C=S).
1
1752 (C=O), 1605 (C=N), 1560 (C–N), 1345 (C=S). H NMR
(DMSO-d6): 2.69 (s, 3H, CH3), 3.44 (s, 3H, CH3), 8.62 (s, 1H,
CH). 13C NMR 24.4 (CH3), 31.8 (CH3), 142.5 (CH), 167.4
(C=S), 167.7 (C=O).
Crystal Structure Determination. Crystal data for
compound 2: C8H14N4OS, Mr = 214.29, space group P(-1), a
= 8.765(3) Å, b = 10.798(5) Å, c = 12.575(5) Å, ꢁ =
67.31(4)°, ꢂ = 80.12(3)°, ꢃ = 78.63(3)°, V = 1070.5(8) Å3, Z
= 4, dcalc = 1.330 g cm-3, colorless prism, 0.56 ꢄ 0.36 ꢄ 0.09
mm, μ = 0.278 mm-1.
Single-crystal diffraction data were measured at room
temperature in the ꢀ/2ꢁ mode on the Oxford Diffraction
Xcalibur diffractometer using graphite-monochromated Mo
Kꢂ radiation (ꢅ = 0.71073 Å). The stability of intensities was

1896
M. Wujec, M. Swatko-Ossor, L. Mazur, Z. Rzaczynska and A. Siwek
Vol 45
monitored by measurement of
3
standards every 100
over a quarter of the plate on Mueller-Hinton Agar and
incubated overnight at 37°C.
reflections. Crystal structure was solved by direct methods
using SHELXS97 [15] program and refined by the full-matrix
least-squares on F2 using the SHELXL97 [16] program. All
non-hydrogen atoms were refined with anisotropic
displacement parameters. H-atoms bonded to C(3) and C(13)
atoms were located from a difference Fourier map and their
positional parameters were not refined. The remaining
hydrogen atoms were positioned geometrically and allowed to
ride on their parent atoms, with Uiso(H) = 1.2 Ueq(C). Final
discrepancy factors are R1 = 0.0666, wR2 = 0.1022 for I >
2ꢀ(I), GOOF = 0.977, ꢁꢀmin, max = ꢂ0.24/0.21 e Å-3.
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