The structure-antituberculosis activity relationships study in a series of 5-aryl-2-thio-1,3,4-oxadiazole derivatives

Article abstract of DOI:10.1016/j.bmc.2011.09.038

A series of 82 5-aryl-2-thio-1,3,4-oxadiazole derivatives were screened for their anti-mycobacterial activities against Mycobacterium tuberculosis H37Rv. The synthesized compounds 30-37 appeared to be the most active derivatives exhibiting more than 90% inhibition of mycobacterial growth at 12.5 μg/mL. Structure-activity relationships study was performed for the given series by using the electronic-topological method combined with neural networks (ETM-NN). A system for the anti-mycobacterial activity prediction was developed as the result of training associative neural network (ASNN) with weights calculated from projections of a compound and each pharmacophoric fragment found on the elements of the Kohonen's self-organizing maps (SOMs). From the detailed analysis of all compounds under study, the necessary requirements for a compound to possess antituberculosis activity have been formulated. The analysis has shown that any requirement's violation for a molecule implies a considerable decrease or even complete loss of its activity. Molecular docking studies of the compounds allowed shedding light on the binding mode of these novel anti-mycobacterial inhibitors.

Full text of DOI:10.1016/j.bmc.2011.09.038

Bioorganic & Medicinal Chemistry 19 (2011) 6792–6807
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
The structure–antituberculosis activity relationships study in a series
of 5-aryl-2-thio-1,3,4-oxadiazole derivatives
Fliur Macaev a, , Zinaida Ribkovskaia a, Serghei Pogrebnoi a, Veaceslav Boldescu a, Ghenadie Rusu a,
⇑
c
d
Nathaly Shvets b, Anatholy Dimoglo b, , Athina Geronikaki , Robert Reynolds
⇑
a Institute of Chemistry, Academy of Sciences of Moldova, Academiei Str. 3, Chisinau MD2028, Republic of Moldova
b Gebze Institute of Technology, PK-141, Gebze/Kocaeli 41400, Turkey
c Aristotelian University of Thessaloniki, Thessaloniki 54124, Greece
d Southern Research Institute, Birmingham, AL 35255-5305, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 13 June 2011
Revised 11 September 2011
Accepted 21 September 2011
Available online 29 September 2011
A series of 82 5-aryl-2-thio-1,3,4-oxadiazole derivatives were screened for their anti-mycobacterial
activities against Mycobacterium tuberculosis H37Rv. The synthesized compounds 30–37 appeared to be
the most active derivatives exhibiting more than 90% inhibition of mycobacterial growth at 12.5 lg/
mL. Structure–activity relationships study was performed for the given series by using the electronic-
topological method combined with neural networks (ETM–NN). A system for the anti-mycobacterial
activity prediction was developed as the result of training associative neural network (ASNN) with
weights calculated from projections of a compound and each pharmacophoric fragment found on the
elements of the Kohonen’s self-organizing maps (SOMs). From the detailed analysis of all compounds
under study, the necessary requirements for a compound to possess antituberculosis activity have been
formulated. The analysis has shown that any requirement’s violation for a molecule implies a consider-
able decrease or even complete loss of its activity. Molecular docking studies of the compounds allowed
shedding light on the binding mode of these novel anti-mycobacterial inhibitors.
Keywords:
Antituberculosis activity
Structure–activity relationships
Electronic-topological method
Neural networks
Docking
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
caused by many factors: inconsistent or partial treatment and lack
of compliancy (sometimes patients do not take all their medicines
Tuberculosis (TB) remains the number one killer infectious dis-
ease affecting adults in developing countries. TB is a global emer-
gency and is amongst the worldwide health threats today.1 The
situation is more complicated when one considers countries such
as India where TB disproportionately affects the young. India ac-
counts for one-third of the global TB burden, with 1.8 million
developing the disease each year and nearly 0.4 million dying
due to TB annually.
The World Health Organization (WHO) estimates that the larg-
est number of new TB cases in 2004 occurred in WHO’s South-East
Asia Region, which accounted for 33% of incident cases globally.
However, the estimated incidence per capita in sub-Saharan Africa
is nearly twice that of the South-East Asia Region, at nearly 400
cases per 100,000 population.2,3
regularly for the required period because they start to feel better),
prescription of wrong treatment regimens, or unreliable drug sup-
ply. A particularly dangerous form of TB is that caused by multi-
drug-resistant TB (MDR-TB), defined as bacilli resistant to at least
isoniazid and rifampicin, the two most powerful anti-TB drugs.4,5
While drug-resistant TB is generally treatable, it requires extensive
chemotherapy (up to 2 years of treatment) that is often prohibi-
tively expensive (often more than 100 times more expensive than
treatment of drug-susceptible TB), in addition to being more toxic
to patients. Noteworthy, the development of drug resistance also
involves other poverty-related diseases, such as malaria and HIV/
AIDS.4–8
Over the last two decades current control efforts are severely
hampered due to Mycobacterium tuberculosis is a leading opportu-
nistic infection in patients with the acquired immune deficiency
syndrome and also due to the spread of multidrug-resistant strains
(MDR-MTB). Problems in the chemotherapy of tuberculosis arise
when patients develop bacterial resistance to the first-line drugs:
isoniazid (INH), rifampicin (RIF), etambutol (ETH), streptomycin
(STR), and pyrazinamide (PYR). The emergence of new strains of
M. tuberculosis resistant to some or all current antituberculosis
drugs is a serious and crescent problem.9
Until 50 years ago, there were no medicines to cure TB. Now,
strains that are resistant to single drugs have been documented in
every country surveyed, and unfortunately, strains of TB resistant
to all major anti-TB drugs have emerged. Drug-resistant TB is
⇑
Corresponding authors. Tel.: +90 262 605 32 06; fax: +90 262 653 84 90 (A.D.).
E-mail addresses: flmacaev@cc.acad.md (F. Macaev), dimoglo@gyte.edu.tr
(A. Dimoglo).
0968-0896/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2011.09.038

F. Macaev et al. / Bioorg. Med. Chem. 19 (2011) 6792–6807
6793
The current second-line drugs used in lengthy combination
therapies to treat MDR-TB (typically over 2 years) mostly have re-
duced potency and (or) greater toxicity than existing first-line
agents, and they may be largely ineffective against extensively
drug-resistant tuberculosis (XDR-TB).10
substrate to reagent revealed that 1.0 equiv of 1 and 1.0 equiv of 4-
(chloromethyl)pyridine hydrochloride to 2.0 equiv. of Et3N was the
optimal ratio. Further, reactions of 2-S-substituted-5-[(4)-isothioc-
yanatophenyl]-1,3,4-oxadiazoles 12–19 with amines have led to
thioureas 20–38 with high yields.
Since no effective vaccine is available, the major strategy to
combat the spreading of TB is the chemotherapy.11 The ever-
increasing resistance, toxicity and side effects of currently used
antituberculosis drugs, together with the absence of their bacteri-
cidal activity, highlight the need for new, safer and more effective
antituberculosis drugs.
1,3,4-Oxadiazoles form an important class of five-member het-
erocyclic compounds with a wide range of biological activities.11
The importance of the oxadiazoles’ nucleus is well established in
agricultural and pharmaceutical chemistry as far as its correspond-
ing derivatives are used as antipyretic, analgesic, antidepressant,
antimicrobial,12 antiviral, fungicidal, antineoplasic,11 anti-inflam-
matory agents, central nervous system stimulants, and anticonvul-
sive, anticancer, and antihypertensive agents.13 Their important
structural characteristic is the presence of two aromatic rings
spaced by a heteroatom.13
The knowledge of quantitative relationships between chemical
structure and biological activity is an essential prerequisite for
the effective search for biologically active compounds.14 Earlier it
was reported that a number of 2,5-disubstituted-1,3,4-oxadiazoles
have been designed, synthesized, and screened for their antituber-
culosis activity against M. tuberculosis H37Rv.15 The compounds
obtained have been tested according to the model developed in
this study.
During this investigation, a variety of amines were tested after-
wards in the selected reaction of substrate 2 in boiling benzene
(compounds 39–47). As shown, hydrazine gives the best result
(84% yields) among the tested models (Table 2, entry 44). The opti-
mized protocol was then expanded to a variety of BrCH2-activated
alkylating reagents and 2-mercapto-5-(3-isothiocyanatophenyl)-
1,3,4-oxadiazole 2. Variations of electronic properties of the
substituents were tolerable, with yields ranging from 70% to 88%
(entries 48–55).
More important is that under the optimal conditions, two-com-
ponent reactions between isothiocyanates 48–52, 54, 55 and
amines proceeded smoothly and provided the desired products in
good to excellent yields. It is worth noting that the reaction be-
tween 54 and 25% aq ammonia proceeded cleanly for only 3 h
and afforded the corresponding 1,3,4-oxadiazole 68 in 87% yield
(entry 68). Synthesized compounds were characterized both by
elemental and spectroscopic analyses (IR, NMR). Table 1 contains
data on the structures of all compounds in this series.
The synthesized compounds were tested for their in vitro
anti-mycobacterial activities against M. tuberculosis H37Rv on the
BACTEC 12B medium using a broth microdilution assay, the
Microplate Alamar Blue Assay (MABA).28 Rifampicin was used as
a standard in the anti-mycobacterial assays. The results of antitu-
bercular activity are reported in Table 1.
Anti-bacterial and -tuberculosis activities of compounds pos-
sessing azole ring have been reported in numerous studies.16–19
As a part of our ongoing studies in developing of new active com-
pounds with anti-mycobacterial activity we report here a multi-
step synthesis of 5-aryl-2-thio-1,3,4-oxadiazoles and our efforts
to relate biological activity data to the nature of substituents in
these compounds. Better understanding of structural requirements
to substituted-1,3,4-oxadiazole derivatives that cause the antitu-
berculosis activity of the latter, will help us to identify lead com-
pounds for our future work.
A combined approach that is known as electron-topological
method (ETM), followed by the artificial neural networks applica-
tion to its results (in short, ETM–ANNs approach20) was used in or-
der to find more potent and selective antimicrobial agents against
M. tuberculosis H37Rv. Both ETM and ETM–ANNs approaches have
already been successfully applied to a wide enough variety of tasks
related to the structure–activity relationships (SAR) investiga-
tions.21–26
The initial isothiocyanates (1, 2) showed low inhibitory activity
(2% and 9%, respectively). Compounds (12–19) derived from iso-
thiocyanate 1 exhibit moderate activity (12–56%), except of com-
pound 18 (2%), while compounds (48–55) derived from
isothiocyanate 2 are completely inactive. The best antituberculose
activity was observed for compound 19 (56%) followed by com-
pound 12 (37%). It seems that bulky substituents in position 2
of the benzene ring are not favorable for the antitubercular
activity.
It should be mentioned that compounds 4, 23–25, 27–37, and
75 (58–98%) were the most active among the compounds tested.
A significant increase of activities (up to 90%, 96%, and 98%) can
be observed in the series of derivatives with monoethanolamine
residues, substituted to the mercapto-group with 4-fluorophena-
cyl, phenacyl, allyl, and 2,4-dichlorophenacyl, respectively (com-
pounds 29, 32, 33, and 36).
All investigated monosubstituted thioureas, derivatives of
4-aminobenzoic acid have been substituted on the SH-group, show
high percents of inhibition. Thus, for example, derivatives of this
type with residues of pyrimidine, benzyl, allyl and c-picolyl (com-
2. Syntheses and bioactivity estimation
pounds 28, 30, 35, and 37) showed the activity indices as 87%, 91%,
98%, and 97% of inhibition, respectively. Also, very high indices of
activity are observed for phenacylated derivatives in this series;
as an example, compounds 27 and 31 with residues of phenacyl
and 2,4-dichlorophenacyl have indices of activity equal to 61%
and 93%, correspondingly.
In the investigated group of 1,3,4-oxadiazoles, derivatives of
4-aminobenzoic acid show a greater activity than corresponding
meta-isomers, in most cases. Also, it is important to mention that
the best activity indices are shown by 1,3,4-oxadiazoles on the ba-
sis of ammonia and monoethanolamine substituted on the mer-
capto-group. Among them, the best result of 98% was exhibited
by compound 35 (monosubstituted thiourea) with an allylated
fragment of the thiolic group and also by compound 36 being
2,4-dichlorophenacylated derivative with a monoethanolamine
residue.
The synthesis of target 1,3,4-oxadiazoles was accomplished by
the following synthetic route (Fig. 1). Due to the presence of two
high reactive groups in molecules 1, 2,27 the –SH group alkylation
reaction and addition of different nucleophiles to isothiocyanate
group can lead to a large number of new compounds.
At the outset of this study it was observed that reactions of
2-mercapto-5-(4-isothiocyanatophenyl)-1,3,4-oxadiazole
1 with
different amines in refluxing benzene gave corresponding substi-
tuted thioureas 3–11 with 68% up to 92% yield. Sulfides 12–19
can be prepared by the treatment of thiol 1 with alkyl halides.
Depending on the nature of the alkylating reagent, the synthesis
was carried out either in acetone in the presence of Et3N (com-
pounds 12–14, 16–19), or in DMF in the presence of K2CO3 (com-
pound 15). In case of compound 13, the screening of the ratio of

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F. Macaev et al. / Bioorg. Med. Chem. 19 (2011) 6792–6807
N
N
O
N
N
N
N
SH
SH
O
O
HS
NH
S
a
a
HN
R1
X
R2
1 R1= -NCS, R2=H
39-47
S
X
3-11
1
2
2
R =H, R = -NCS
b
a
b
N
N
N
N
N
R3-S
N
S-R3
S-R3
O
O
a
O
R1
SCN
NCS
12-19
R2
20-38, 56-82
48-55
a: amines; b: Hal-R3, K2CO3/DMF or Et3N/acetone;
X=NH2, NH-Me, NH-Et, NH-p-tolyl, NH-allyl, NH(CH2)2OH, NHBn, 4-PyCH2NH, ArC(O)CH2NH, piperidine,
morpholine, 4-amino-1,2,4-triazole, hydrazones
Figure 1. Synthesis of 5-aryl-2-thio-1,3,4-oxadiazole derivatives.
Rv1155 from M. tuberculosis were minimized up to a gradient of
0.01 kcal/(mol Å), and hydrogens were added using the force field
AMBER99. Charges on the protein were assigned using the force
field AMBER99, while the charges on the ligands were assigned
by using force field MMF94X. The final energy was calculated using
the Generalized Born solvation model (GB/VI).
3. Computational methods
3.1. Docking studies
Docking as one of approaches to computer-assisted molecular
modeling (CAMM) plays an essential role in the design of potential
ligands that are both sterically and chemically compatible with the
binding site of a target bio-macromolecule.29,30 When performed
with default settings, docking reveals a number of possible confor-
mations and orientations for the inhibitors at the binding site.
Knowing the binding site conformations helps to show the impor-
tant interactions that stabilize the complex ligand–receptor.
Initial molecular structures for docking were found from the
package of quantum-chemistry programs ‘gaussian03’. All structures
were optimized in the aqueous surroundings for further use.
As far as the structures in view are rigid molecular skeletons of
the heterocyclic and ring form, and flexibility of their bonds is re-
stricted, the usage of different optimizing methods causes very
similar results. Structure optimization with docking is useful when
compounds are flexible enough and have a lot of conformations.
Docking could help to select an appropriate conformer in this case.
Crystal structure of the conserved hypothetical protein Rv1155
from M. tuberculosis was obtained from the Protein Data Bank
(http://www.rcsb.org) under the Accession Code 1CI0.pdb (unpub-
lished data).31–33 Pyridoxamine 50-phosphate oxidase (PNPOx) is
the smallest member of the flavin-containing oxidase family that
catalyses the oxidation of pyridoxamine-5-P (PMP) and pyridox-
ine-5-P (PNP) to pyridoxal-5-P (PLP). This reaction serves as the
terminal step in the de novo biosynthesis of PLP in Escherichia coli
and as a part of the salvage pathway of this coenzyme in both E. coli
and mammalian cells. A 10 Å sphere around the center of the bind-
ing pocket was defined as binding pocket for the docking.
3.2. ETM method
To begin with, each molecular structure is represented as a ma-
trix called electron-topological matrix of conjunction (ETMC),
which includes values of basic properties related to atoms and
bonds of a molecule (charges, HOMO/LUMO orbitals, atomic
distances, etc.).
In accordance with the main steps of the ETM-study, optimized
geometry data and electronic characteristics calculated from the
semi-empirical AM1 method35,36 are used in ETMCs that have been
formed previously for all compounds (82 molecules). By this, effec-
tive charges on atoms (qi, local atomic characteristics) were chosen
as diagonal elements for the matrices; and either values of a bond
characteristic (here, Wiberg’s indices, Wij, for bonds) or optimized
0
distances (Rij, in AÅ), otherwise, were used as their off-diagonal
elements.
All compounds fall into classes of active molecules (17 mol,
inh % >55), low active molecules (17 mol, 16 <inh % <55) and inac-
tive ones (48, mol, inh % <15), in a natural way. Optimal values of
allowable variations that have been found in the process of the
matrices comparison (when testing if their atoms and bonds
match) were found as D1
= 0.07 for diagonal elements (qi) and
D2
=
0.20 for off-diagonal values (Wij and Rij). To determine the
most informative activity features, the lowest level of probabilistic
estimations, Pa, was taken as 0.80.
Molecular mechanics techniques were used to minimize the li-
gand energy in the binding pocket, starting from a series of random
positions and orientations within the binding site. The ligand
structures had been energy-minimized by using the MMFF94s
force field and the conjugated gradient method, until the default
derivative convergence criterion of 0.05 kcal/(mol Å) was reached.
For the docking studies we used Molecular Operating Environ-
ment (MOE) software running on Windows-based PC34 to estimate
free energy of binding of the ligand in the poses given. The docked
poses were scored using a London dG scoring function for finding
the best docking pose. The protein–ligand complexes of protein
Pa ¼ ðn1 þ 1Þ=ðn1 þ n2 þ 2Þ:
Here n1 is the number of molecules possessing the Si activity
fragment (pharmacophore) in the class of active compounds, and
n2 has the same meaning but in the class of inactive compounds
(anti-pharmacophore), as found by the ETM.
To have more stable activity fragments, every active compound
was used as a template for comparison with the rest of ETMCs in
the course of the ETM study. After all ETMCs (i.e., active and
inactive ones) had been processed, two corresponding sets of
their common fragments (i.e., pharmacophores and anti-

F. Macaev et al. / Bioorg. Med. Chem. 19 (2011) 6792–6807
6795
Table 1
Synthesized compounds and activity against M. tuberculosis H37Rv (in vitro)
R1
N
N
R2
O
S-R3
No.
No.
1
R1
R2
H
R3
H
Inh (%)
2
R1
H
R2
R3
H
Inh (%)
H
N
S
N
SCN
42
43
13
13
N
N
NH
S
N
2
H
SCN
H
9
H
H
NH
S
S
S
H2N
H2N
3
4
5
H
H
H
H
H
H
0
70
0
44
45
46
H
H
H
H
H
H
0
13
5
N
H
NH
S
N
H
H2N
NH
S
NH
NH
S
H
N
HN
N
NH
S
NH
H
S
N
N
6
7
8
H
H
H
H
H
H
28
9
47
48
49
H
H
H
H
18
0
NH
NH
S
HO
N
SCN
SCN
H2C
N
H
NH
S
H
N
S
CH2
9
0
NH
H
N
CH2
9
10
11
H
H
H
H
H
H
5
6
0
50
51
52
H
H
H
SCN
SCN
SCN
0
0
0
NH
O
O
S
Br
Cl
N
H
NH
CH2
O
H
N
S
H2N
CH2
NH
Cl
CH2
12
13
SCN
SCN
H
H
Me
37
27
53
54
H
H
SCN
SCN
3
5
O
H2C
N
F
H2C
O
H2C
Cl
F
14
15
SCN
SCN
H
H
20
14
55
56
H
H
SCN
HO
N
0
0
CH2
O
N
N
S
HN
NH
CH2
O
O
S
F
16
17
SCN
SCN
H
H
12
22
57
58
H
H
0
0
H2C
O
NH
CH2
O
S
HO HN
HO HN
H2C
NH
S
CH2
Cl
Cl
O
O
18
SCN
H
2
59
H
0
Cl
NH
Cl
H2C
H2C
(continued on next page)

6796
F. Macaev et al. / Bioorg. Med. Chem. 19 (2011) 6792–6807
Table 1 (continued)
No.
R1
R2
H
R3
Inh (%)
56
No.
60
R1
H
R2
R3
Inh (%)
0
S
Cl
CH2
O
19
SCN
H2N
NH
Cl
Cl
H2C
O
H
N
S
S
S
S
H2N
20
H
Me
0
61
H
0
H2N
H2N
NH
NH
NH
H2C
O
NH
H
S
N
21
22
H
H
Me
Me
17
0
62
63
H
H
0
6
H2C
O
NH
S
O
N
Br
H2N
N
NH
H2C
O
H
S
N
S
N
23
24
25
H
H
H
Me
Me
58
78
67
64
65
66
H
H
H
9
16
17
N
N
H2N
NH
S
H2C
HN
S
H2C
O
NH
H2N
NH
S
S
S
HO HN
Br
HO
Me
N
H
NH
NH
H2C
O
S
N
H2C
N
Cl
F
HO HN
S
26
27
28
29
H
H
H
H
25
61
87
90
67
68
69
70
H
H
H
H
18
19
12
10
H2C
O
NH
NH
S
O
H2N
NH
H2N
NH
H2C
H2C
O
S
N
S
HO HN
H2N
NH
N
NH
H2C
O
S
O
S
N
HO HN
S
F
H2C
H2C
NH
NH
H2C
O
S
30
31
H
H
91
93
71
72
H
H
16
13
H2N
NH
H2N
NH
H2C
S
Cl
S
O
HO HN
H2C
H2N
NH
Cl
NH
H2C
O
S
H2N
HO
S
HO HN
HO HN
32
33
H
H
96
96
73
74
H
H
Me
Me
25
8
NH
H2C
H2C
NH
S
S
CH2
N
H
NH
NH
S
H
N
S
HO HN
S
N
34
35
H
H
97
98
75
76
H
H
Me
Me
58
0
N
N
NH
HN
H
N
CH2
Cl
S
H2N
H2N
NH
NH
S
H
S
N
O
H2C
H2C
HO HN
36
H
98
77
H
Me
21
Cl
NH
NH
S
O
N
N
S
37
38
H2N
NH
H
H
97
14
78
79
H
H
Me
Me
0
8
HN
S
N
H
N
S
HO HN
N
NH
N
NH

F. Macaev et al. / Bioorg. Med. Chem. 19 (2011) 6792–6807
6797
Table 1 (continued)
No.
R1
R2
R3
H
Inh (%)
0
No.
80
R1
H
R2
R3
Inh (%)
S
S
Cl
N
O
39
H
1
N
H
NH
S
NH
Cl
H2C
H2C
S
H
N
40
41
H
H
H
H
16
20
81
82
H
H
0
0
N
H2N
HN
NH
NH
S
H
O
N
S
N
NH
H2C
NH
pharmacophores) were obtained. These sets are already capable to
assist experts in computer screening of new drug prototypes as
well as in forecasting their activities.
(2) Initialize the Kohonen’s network parameters; and, for each
molecule, calculate clusters from its ETMC. The initial size
of Kohonen’s maps is taken as S = 2 ⁄ SETMC, where SETMC is
the size of the largest molecular matrix.
3.3. ETM–ANNs approach
(3) Find common ETMCs fragments. For each fragment, calcu-
late its projection on the units of the Kohonen’s SOM. Calcu-
late the projection error (Eq). Calculate the weight of each
fragment (1/Eq) and create new data set by using the calcu-
lated fragment weights as parameters.
(4) Analyze ETM-data as to fragments (i.e., ETSC) by using
ASNNs; calculate the average prediction error (Ec).
(5) Compare the Ec value to that one found at the preceding
stage of learning, Ep (initially, Ep = 10e-3). If Ec < Ep, the cur-
rent projection of the ETSC for the fragment is saved.
(6) Decrease the size of the Kohonen’s map.
As seen, the aim of the ETM approach is to find molecular frag-
ments (pharmacophores) common for the structures of all active
compounds (for an activity selected) and absent in all inactive
compounds with similar structures. The set of pharmacophores
and antipharmacophores revealed as the result of the ETMCs anal-
ysis, are basic molecular substructures that form a system for the
given activity prognostication. The system can be used for testing
newly synthesized compounds, so as for the computer modeling
of new candidates for the purposeful syntheses.37–40
However, the procedure of the activity prediction is difficult en-
ough and needs the expert’s participation. To automate this proce-
dure, the ETM application was followed by the ANNs application
(with unsupervised and supervised learning algorithms), and, as
a result, these calculations were named as the ETM–ANNs com-
bined approach.20 The ANNs application uses data resulting from
the ETM calculations (corresponding electron-topological subma-
trices of contiguity for pharmacophores and anti-pharmacophores,
ETSC, in short) as input for a new algorithm developed on the base
of Volume Learning Algorithm that had been created previously for
the analysis of CoMFA data.41,42 This algorithm is implemented as a
recurrent iterative application of the Kohonen self-organizing
maps (SOMs) and associative neural networks (ASNNs).43,44 The
general block-schema of the ETM–ANNs data analysis is shown
in Figure 2.
(7) Repeat steps 2–6 until the map size, S, decreases to Smin (Smin
equals to eight nodes).
(8) Select the best ETMC fragments’ projections, relative to the
minimal value of Ec, and predict the activity of new
compounds.
(9) Select the most informative ETMC fragments (after the ASNN
training) by using special pruning methods.45,46
(10) Predict activities of new compounds.
The optimized ETMC fragments were used to visualize those re-
gions of molecules under study that were found to be important for
the analyzed activity demonstration by the molecules.
4. Results and discussions
4.1. Docking analysis
According to this algorithm, its main steps are as follows:
Docking of active compound 33 in Rv1155 shows that this com-
pound docks well in the active site that consists of such amino
acids as Ser144, Arg140, Lys78, Tyr88, Ile74, Leu75, and Leu76
(Fig. 3a). The oxygen of the hydroxyl group forms hydrogen bonds
with Ser 144 (distance 2.70 Å) and Arg140 (distance 2.64 Å) of the
protein. The oxadiazole ring is located in the vicinity of amino acids
Leu76 and Leu75. The nitrogen of oxadiazole forms a hydrogen
bond with Leu76 (distance 2.65 Å). Four of amino acids show a
sidechain and backbone acceptor properties. Three of amino acids
(Leu75, Leu76, and Ile74) show backbone donor properties. The
phenyl ring settles in a hydrophobic cavity lined by Lys78, Tyr88,
and Ser89. The dichlorophenyl ring (compounds 31 and 36) is opti-
mally oriented to make aryl cation interaction with the Arg140
(see Fig. 3b). According to docking results, compounds 31 and 36
exhibit a binding mode similar to that of compound 33.
(1) Form the initial set of input data (ETM-data, such as ETMCs,
pharmacophores and anti-pharmacophores).
ETM calculations
and SOM
SOM: training,
Clustering of
ASNN: training,
with mean cluster
values
initialization
ETMC elements
ASNN: pruning
of the redundant
fragments
ETM: fragment
set formation
Selection of the
final model
Visualization of
important fragments
and prediction of
new data
ETM fragment
data calculation
Prediction of
new data
It is interesting to note that inactive compounds 60 and 20 (Fig. 3c
and d) with different structures have close values of weak binding
affinity. As seen from the docking studies, compound 60 in Rv1155
docks well in the active site that consists of the amino acids Ser89,
Figure 2. Block-scheme of data analysis by means of ETM–ANN approach.

6798
F. Macaev et al. / Bioorg. Med. Chem. 19 (2011) 6792–6807
Figure 3. Docking of compounds 33 (a), 31 (b), 60 (c) and 20 (d) into the active site of protein Rv1155 from Mycobacterium tuberculosis. H-atoms of protein are not shown for
clarity.
Arg73, Gln153, Ser154, Tyr88, Ile74, and Leu76 (Fig. 3c). The differ-
ence in its binding mode appears to be the reason behind the differ-
2
ence in binding affinity and, subsequently, in activities of
compounds 33 (binding energy = ꢀ16.23 kcal/mol; docking ener-
gy = ꢀ19.95 kcal/mol) and 60 (binding energy = ꢀ10.35 kcal/mol;
docking energy = ꢀ11.10 kcal/mol). The difference in binding mode
may be attributed to the electronegative nature of carbonyl group,
which favors an orientation that enables hydrogen bonding between
the –C@O group and Leu76. Docking of the inactive compound 20
showed favorable hydrogen bonding interactions between its
NH2-group and Ile74 of the protein (Fig. 3d). According to the dock-
ing results, compound 20 (binding energy = ꢀ10.86 kcal/mol; dock-
ing energy = ꢀ12.06 kcal/mol) exhibits a binding mode similar to
that of compound 60.
From all the said it follows that binding modes for active and
inactive compounds are different. Inactive compounds can be
either rejected by the receptor or binded but with its other amino-
acids then those that bind with active compounds. Binding affini-
ties of inactive compounds are characterized by very low values
in this case.
24
18
3
1
9
11
5
33
C1
0.01
N2
N3
O5
C9
C11
N18
H24
1.58
-0.07
2.18
1.26
1.05
2.25
7.12
6.75
5.46
2.48
3.77
4.60
2.86
6.68
7.87
8.87
7.08
7.59
8.81
9.74
7.90
-0.11 1.08
-0.11 6.13
-0.18 8.95
12.92 13.63
-0.07 4.23
-0.32
5.29
0.88
0.26
Figure 4. Submatrix (ETSC) and corresponding structure of the Ph1 pharmacophore
(template active compound 33).
4.2. Analysis of pharmacophores and anti-pharmacophores
negative charge q = ꢀ0.32e; negative charges are concentrated on
¯
the atoms N3, O5, C9, N2, and C11, as well. The charge on the C1 car-
bon atom is close to zero. The rest of pharmacophores were found
analogously, and the probabilities of their realization (Pa) in the
class of active compounds varied in the limits of 0.80–0.90.
To determine anti-pharmacophores, ETMCs of several inactive
compounds were taken as templates for the comparison with the
rest of compounds. ETSC that corresponds to the APh1 anti-
pharmacophore is given in Figure 4 along with the structure of
To form the basis of the system for the antituberculosis activity
prediction, the compound 33 with the highest activity was taken as
a template for the comparison first of all. In Figure 4, a submatrix of
this template ETMC (i.e., its ETSC) is given, which corresponds to
one of the pharmacophores revealed (namely, to Ph1).
The given Ph1 pharmacophore consists of eight atoms located in
different parts of the template. The nitrogen atom N18 has a high

F. Macaev et al. / Bioorg. Med. Chem. 19 (2011) 6792–6807
6799
the corresponding template from which all anti-pharmacophores
have been found.
ment, while 12 randomly selected compounds were used for the
model validation. For the mentioned training set and test set,
170 fragments were selected from the ETM study. The ASNNs rec-
ognized correctly 90.1%, or 65 from 70 compounds, for the training
set and 92.0%, or 11 compounds from 12, for the test set (Table 3).
The importance of the detected fragments for the antitubercular
activity demonstration was evaluated as the result of using prun-
ing methods at the last step of the algorithm.
The most part of the ETMC fragments were found to be nonsig-
nificant for the system of prognosis and eliminated by the pruning
algorithms. As a result, only three ETMC fragments from 250 se-
lected previously by the experts from all fragments found appeared
to be the most important ones. By this, ASNNs classified correctly
90.4%, or 67 compounds from 70 ones, in the training set and
92.0%, or 11 from 12 compounds, in the test set (Table 2).
As known, the highest occupied molecular orbital (HOMO) and
the lowest unoccupied molecular orbital (LUMO), called also fron-
tier orbitals, play an important role in the donor–acceptor interac-
tion of a substance with the corresponding receptor. Analysis of
HOMOs for the compounds containing Ph1–Ph5 and APh1–APh5
has shown that atoms with the highest values of the atomic orbital
coefficients are mainly those atoms that form the pharmacophores.
The HOMO orbitals are shown in Figure 7.
As seen from Figure 5, APh1 (found from the inactive compound
60 as a template) consists of atoms C9, C11, C20, N23, O26, and Cl27
.
Thus, a set of pharmacophores and anti-pharmacophores was cal-
culated by the ETM relative to the series under study. Both groups
of molecular fragments formed the basis of our system for the pre-
diction of anti-mycobacterial activity against M. tuberculosis H37Rv.
The statistical characteristics of five pharmacophores (Phi) and
five anti-pharmacophores (APhi) entering the forecasting system,
are given in Table 2. Figure 6 shows the frequencies of two phar-
macophores, Ph1 and Ph2, and two anti-pharmacophores, APh1
and APh2, occurrence in the compounds studied and corresponding
values of their activities.
As seen from Figure 6, pharmacophores appear with high fre-
quencies in the class of active compounds, and they are practically
absent in the class of inactive compounds. In a similar way, maxi-
mal values are observed for the frequencies of APh1 and APh2
appearance in the class of inactive compounds, while for Ph1 and
Ph2 their frequencies are close to zero. In other words, the frag-
ments found provide natural clustering of the series under study
into two classes of compounds, namely, active and inactive ones.
When comparing the structures of the pharmacophores and anti-
pharmacophores, one can pay attention to the differences in their
spatial and electron characteristics. Thus, when used together, both
pharmacophores and anti-pharmacophores play definitely very
important role for the activity prediction in the process of search-
ing for a new potential drugs.
HOMO orbital for the template compound 33 consists of orbi-
tals of those atoms that form aminosulfonyl group and, partially,
phenyl and pyrazole rings. The most part of atoms representing
Ph1 are exactly those that deposit considerably to the HOMO orbi-
tals. Similar situation can be observed in the case of template com-
pounds 35–37. In contrast to Ph1, HOMO orbital of APh1 consists of
carbon atoms entering the phenyl ring and all atoms of monosub-
stituted thiourea group. All the said suggests an important role of
these atoms in the substrate–receptor interaction.
4.3. ETM–ANNs
The next step of the investigation was the ETM–ANNs combined
approach application. A data set containing 82 molecules was
taken. Seventy of the compounds were used for the model develop-
5. Conclusion
Peculiarities of conformational and electron structures of com-
pounds belonging to a large series of different 5-aryl-2-thio-
1,3,4-thiadiazole derivatives which possess anti-mycobacterial
activity against M. tuberculosis H37Rv have been studied. The re-
sults of the study are in agreement with data obtained by other
researchers relative to the same classes of compounds. A system
for the antituberculosis activity prediction was developed on the
base of pharmacophores and anti-pharmacophores found in the
process of this study. The system allows for the effective screening
of active compounds and design of potent drugs.
The results of the ETM–ANNs application to the test sample show
that 90% of the compounds taken are classified correctly (Table 2).
Obviously, the immediate prediction done on the base of the ETM
can give much higher percentage. To assess the activity of a
molecule, the ETM–ANN uses a set of pharmacophores and anti-
pharmacophores that havebeen found froma few differenttemplate
compounds. For this reason, the percentage of test compounds that
are correctly recognized with the help of ETM–ANN after training by
the targets can sometimes be lower than the percent of test com-
pounds correctly recognized after immediate results of ETM, that
27
20
26
9
11
23
60
C9
C11
C20
N23
O26
Cl27
2.70
4.00
-0.14 1.38
-0.09
11.01 12.53 2.39
11.61 13.39 3.36
-0.14
3.06
10.90 10.92
12.10 11.87
-0.39
-0.23
3.34
0.02
Figure 5. Submatrix (ETSC) and corresponding structure of the APh1 antipharma-
cophore (the template compound 60).
Table 2
Statistical characteristics for some of pharmacophores (Phi) and anti-pharmacophores (APhi) calculated by ETM
Type of pharmacophore
(template compound)
Pa
Pia
Type of antipharmacophore
(template compound)
Pa
Pia
Ph1 (33)
Ph2 (35)
Ph3 (36)
Ph4 (37)
Ph5 (32)
0.90
0.87
0.85
0.83
0.80
0.10
0.13
0.15
0.17
0.20
APh1 (59)
APh2 (44)
APh3 (60)
APh4 (49)
APh5 (61)
0.07
0.09
0.13
0.08
0.10
0.93
0.91
0.87
0.92
0.90

6800
F. Macaev et al. / Bioorg. Med. Chem. 19 (2011) 6792–6807
Britain). Thin-layer chromatography was carried out on Merck alu-
Low active compounds
Active compounds
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
minum sheets, silica gel 60 F254. Column chromatography was per-
formed on Fluka silica gel 60, 70–230 mesh. Melting points were
determined on a Boëtius melting point apparatus (PHMK, VEB
Wägetechnik Rapido, Radebeul, Germany) and are uncorrected. IR
spectra were acquired on apparatus ‘Perkin–Elmer Spectrum 100
FTIR’. 1H NMR spectra were acquired on a Bruker Avance III 400
spectrometer operating at 400.13 MHz for 1H. Chemical shifts d
are given in ppm referring to the signal center using the solvent
peaks for reference: DMSO-d6 2.50 ppm.
Ph1
Ph2
APh1
APh2
0
10
20
30
40
50
60
70
80
90
100
6.1. Precursors of compounds 3–82
Inhibition. %
Figure 6. Frequency of the pharmacophores’ (antipharmacophore’s) occurrences in
the compounds studied.
1,3,4-Oxadiazoles 1, 2 were prepared according to a known
procedure.27
6.1.1. 5-(4-Isothiocyanatophenyl)-1,3,4-oxadiazole-2-thiol (1)
Table 3
Yield: 90%, mp: 197–199 °C. IR: 1612 (C@N), 2040 (NCS), 3066
(SH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz): 3.11 (s, 1H,
;
The ETM–ANNs results based on data obtained from the pharmacophores set
SH), 7.88 (d, 2H, J = 8.94 Hz, Ar), 7.02 (d, 2H, J = 8.94 Hz, Ar). Anal.
Calcd for C9H5N3OS2 (MW 235.29): C, 45.94; H, 2.14; N, 17.86.
Found: C, 45.87; H, 2.17; N, 17.92.
All pharmacophores
WD* number
Molecule
Predicted (%)
s
Amount
Training set
Test set
Pharmacophores selected by pruning methods
250
250
70
12
65 (90.1)
11 (92.0)
6.1.2. 8.1.2.5-(3-Isothiocyanatophenyl)-1,3,4-oxadiazole-2-thiol
(2)
Yield: 85%, mp: 138–140 °C. IR: 1615 (C@N), 2105 (NCS), 3083
Training set
Test set
10
10
70
12
67 (90.4)
11 (92.0)
(SH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz): 7.48–8.1 (m,
;
4H, Ar), 10.8 (s, 1H, SH). Anal. Calcd for C9H5N3OS2 (MW 235.29):
C, 45.94; H, 2.14; N, 17.86. Found: C, 45.88; H, 2.18; N, 17.82.
*
WDs, weight descriptors.
6.2. General procedure for the synthesis of S-substituted 1,3,4-
oxadiazoles 12–19, 48–55
is, from the set of pharmacophores calculated for a single target
compound.
The work on the volume of the set of possible pharmacophores/
anti-pharmacophores reduction is an expert’s work and is tedious
enough. Unfortunately, it cannot be automated completely, and the
expert’s participation at this stage is obligatory. Neural networks
can improve the results of this work as to finding the most signif-
icant activity fragments. Moreover, they can be trained to predict
activities of new potent preparations, and after this they can be
purposefully used by nonexperts, too.
To the stirred solution of 1,3,4-oxadiazole (4.2 mmol) and tri-
ethylamine (0.42 g, 4.2 mmol) in acetone (20 ml), one-portion
solution of
x-phenacyl bromide (4.6 mmol) in acetone (5 ml)
was added at room temperature. The reaction mixture was stirred
for 2 h at room temperature (TLC control). The precipitate formed
was filtered and washed with water and acetone. The same meth-
od was used for allyl bromide, benzyl chloride, methyl iodide.
The most active compounds dock well in the active site of the
related enzymes. Inhibitory activity of the most potent compounds
is explained mostly by hydrogen bonding and either electrostatic
6.2.1. 5-(4-Isothiocyanatophenyl)-2-methylsulfanyl-1,3,4-oxa-
diazole (12)
Yield: 90%, mp: 113–114 °C. IR: 1195 (SCH3), 1456 (C@N), 2230
(NCS) cmꢀ1; 1H NMR (d ppm, DMSO-d6, 400 MHz): 2.81 (s, 3H, Me),
7.48–7.97 (m, 4H, Ar). Anal. Calcd for C10H7N3OS2 (MW 249.31): C,
48.17; H, 2.83; N, 16.85. Found: C, 48.21; H, 2.78; N, 16.89.
or
p–p interactions within the active site of the enzyme. Hydro-
philic and steric requirements are also very important factors in
terms of SAR. Thus, this study can be a good starting point to im-
prove the design of novel class of molecules possessing antituber-
culosis activity.
6.2.2. 2-(4-Pyridylmethylsulfanyl)-5-(4-isothiocyanatophenyl)-
1,3,4-oxadiazole (13)
6. Experimental part
To the stirred at rt solution of 2-mercapto-5-(4-isothiocyana-
tophenyl)-1,3,4-oxadiazole (1.41 g, 6 mmol) and triethylamine
(1.21 g, 12 mmol) in acetone (30 ml), one-portion suspension of
4-chloromethylpyridine hydrochloride (1.0 g, 6,1 mmol) in acetone
Solvents and commercially available reagents were purchased
from Aldrich (Germany), Across (Belgium), and Lancaster (Great
Figure 7. A three-dimensional view of HOMO orbitals for template compounds 33 (a) and 60 (b).

F. Macaev et al. / Bioorg. Med. Chem. 19 (2011) 6792–6807
6801
(10 ml) was added in. The reaction mixture was refluxed for 2 h
6.2.9. 5-(3-Isothiocyanatophenyl)-2-phenylethylsulfanyl-1,3,4-
oxadiazole (48)
Yield: 84%, mp: 59–61 °C. IR: 1621 (C@N), 2134 (NCS), 2789
(SCH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz): 3.08 (t, 2H,
(TLC control). When the reaction was completed, acetone was
evaporated under reduced pressure, precipitate was suspended
with water, filtered, washed with water and acetone.
;
Yield: 80%, mp: 151–152 °C. IR:1600 (C@N), 2096 (NCS), 2591
J = 7.97 Hz, CH2S), 3.56 (t, 2H, J = 7.97 Hz, CH2Ar), 7.15–7.34 (m,
5H, Ar), 7.58–7.98 (m, 4H, Ar). Anal. Calcd for C17H13N3OS2 (MW
339.43): C, 60.15; H, 3.86; N, 12.38. Found: C, 60.21; H, 3.89; N,
12.42.
(SCH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz): 4.51 (s, 2H,
;
CH2), 7.43–8.58 (m, 8H, Ar). Anal. Calcd for C15H10N4OS2 (MW
326.40): C, 55.20; H, 3.09; N, 17.17. Found: C, 55.25; H, 3.11; N,
17.21.
6.2.10. 2-Benzylsulfanyl-5-(3-isothiocyanatophenyl)-1,3,4-oxa-
diazole (49)
6.2.3. 2-Benzylsulfanyl-5-(4-isothiocyanatophenyl)-1,3,4-oxa-
diazole (14)
Yield: 88%, mp: 80–81 °C. IR: 1640 (C@N), 2036 (NCS), 2720
Yield: 81%, mp: 139–141 °C. IR: 1603 (C@N), 2098 (NCS), 2724
(SCH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz): 4.59 (s, 2H,
;
(SCH2) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz): 4.51 (s, 2H,
CH2), 7.27–7.98 (m, 9H, Ar). Anal. Calcd for C16H11N3OS2 (MW
325.41): C, 59.06; H, 3.41; N, 12.91. Found: C, 59.11; H, 3.44; N,
12.87.
CH2), 7.23–8.11 (m, 9H, Ar). Anal. Calcd for C16H11N3OS2 (MW
325.41): C, 59.06; H, 3.41; N, 12.91. Found: C, 59.11; H, 3.44; N,
12.96.
6.2.11. 2-[5-(3-Isothiocyanatophenyl)-1,3,4-oxadiazol-2-yls-
ulfanyl]-1-(2-naphthyl)-1-ethanone (50)
6.2.4. 2-(2-pyrimidinylsulfanyl)-5-(4-isothiocyanatophenyl)-
1,3,4-oxadiazole (15)
Yield: 78%, mp: 175–177 °C. IR: 1498 (C@N), 1673 (C@O), 2230
Suspension of 2-mercapto-5-(4-isothiocyanatophenyl)-1,3,4-
oxadiazole 1 (1.17 g, 5 mmol) and K2CO3 (1.4 g, 10 mmol) in DMF
(10 ml) was stirred during 5 min at rt, then solution of 2-chloro-
pyrimidine (0.57 g, 5 mmol) in DMF (5 ml) was added. The reaction
mixture was stirred for 3 h at 130 °C (TLC control). After this peri-
od, the reaction mixture was cooled to rt, water (50 ml) was added,
and precipitate formed was filtered, washed with water, dried and
recrystallized from ethanol.
(NCS), 2879 (SCH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
5.33 (s, 2H, CH2), 7.50–8.22 (m, 11H, Ar). Anal. Calcd for
C21H13N3O2S2 (MW 403.04): C, 62.51; H, 3.25; N, 10.41. Found: C,
62.55; H, 3.27; N, 10.48.
6.2.12. 1-(4-Bromophenyl)-2-[5-(3-isothiocyanatophenyl)-1,3,4-
oxadiazol-2-ylsulfanyl]-1-ethanone (51)
Yield: 76%, mp: 165–167 °C. IR: 1515 (C@N), 1675 (C@O), 2176
Yield: 65%, mp: 173–175 °C. IR: 1554 (C@N), 2090 (NCS) cmꢀ1
;
(NCS), 2770 (SCH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
1H NMR (d ppm, DMSO-d6, 400 MHz): 7.33–8.65 (m, 7H, Ar). Anal.
Calcd for C13H7N5OS2 (MW 313.36): C, 49.83; H, 2.25; N, 22.35.
Found: C, 49.85; H, 2.31; N, 22.38.
5.17 (s, 2H, CH2), 7.61–8.15 (m, 8H, Ar). Anal. Calcd for
17H10BrN3O2S2 (MW 432.31): C, 47.23; H, 2.33; N, 9.72. Found:
C
C, 47.27; H, 2.27; N, 9.78.
6.2.5. 1-(4-Fluorophenyl)-2-[5-(4-isothiocyanatophenyl)-1,3,4-
oxadiazol-2-ylsulfanyl]-1-ethanone (16)
6.2.13. 1-(2,4-Dichlorophenyl)-2-[5-(3-isothiocyanatophenyl)-
1,3,4-oxadiazol-2-ylsulfanyl]-1-ethanone (52)
Yield: 91%, mp: 183–185 °C. IR: 1585 (C@N), 1675 (C@O), 2113
Yield: 81%, mp: 141–143 °C. IR: 1540 (C@N), 1677 (C@O), 2132
(NCS), 2605 (SCH2) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz):
(NCS), 2667 (SCH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
5.19 (s, 2H, CH2), 7.42–7.84 (m, 8H, Ar). Anal. Calcd for
17H10FN3O2S2 (MW 371.41): C, 54.97; H, 2.71; N, 11.31. Found:
5.02 (s, 2H, CH2), 7.54–7.99 (m, 7H, Ar). Anal. Calcd for
17H9Cl2N3O2S2 (MW 422.31): C, 48.35; H, 2.15; N, 9.95. Found:
C
C
C, 54.92; H, 2.74; N, 11.37.
C, 48.39; H, 2.19; N, 9.92.
6.2.6. 2-[5-(4-Isothiocyanatophenyl)-1,3,4-oxadiazol-2-ylsulfa-
nyl]-1-phenyl-1-ethanone (17)
6.2.14. 2-Allylsulfanyl-5-(3-isothiocyanatophenyl)-1,3,4-oxa-
diazole (53)
Yield: 78%, mp: 168–170 °C. IR: 1594 (C@N), 1676 (C@O), 2114
Yield: 70%, mp: 43–45 °C. IR: 1560 (C@N), 2134 (NCS), 2556
(NCS), 2725 (SCH2) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz):
(SCH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz): 3.94 (d, 2H,
;
4.99 (s, 2H, CH2), 7.24–7.68 (m, 5H, Ar), 7.91–8.12 (m, 4H, Ar). Anal.
Calcd for C17H11N3O2S2 (MW 353.42): C, 57.77; H, 3.14; N, 11.89.
Found: C, 57.73; H, 3.16; N, 11.94.
J = 6.74 Hz, CH2-CH), 5.12–5.44 (m, 2H, CH2@CH), 5.85–6.18 (m,
1H, CH@CH2), 7.47–7.87 (m, 4H, Ar). Anal. Calcd for C12H9N3OS2
(MW 275.35): C, 52.34; H, 3.29; N, 15.26. Found: C, 52.36; H,
3.32; N, 15.33.
6.2.7. 1-(2,4-Dichlorophenyl)-2-[5-(4-isothiocyanatophenyl)-
1,3,4-oxadiazol-2-ylsulfanyl]-1-ethanone (18)
6.2.15. 1-(4-Fluorophenyl)-2-[5-(3-isothiocyanatophenyl)-1,3,4-
oxadiazol-2-ylsulfanyl]-1-ethanone (54)
Yield: 83%, mp: 169–170 °C. IR: 1517 (C@N), 1664 (C@O), 2135
(NCS), 2724 (SCH2) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz):
Yield: 79%, mp: 133–134 °C. IR: 1587 (C@N), 1676 (C@O), 2245
4.87 (s, 2H, CH2), 7.52–8.08 (m, 7H, Ar). Anal. Calcd for
17H9Cl2N3O2S2 (MW 422.31): C, 48.35; H, 2.15; N, 9.95. Found:
(NCS), 2600 (SCH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
C
5.19 (s, 2H, CH2), 7.42–7.92 (m, 8H, Ar). Anal. Calcd for
C17H10FN3O2S2 (MW 371.41): C, 54.97; H, 2.71; N, 11.31. Found:
C, 48.39; H, 2.19; N, 9.92.
C, 54.92; H, 2.75; N, 11.38.
6.2.8. 2-Allylsulfanyl-5-(4-isothiocyanatophenyl)-1,3,4-oxa-
diazole (19)
6.2.16. 1-(4-Chlorophenyl)-2-[5-(3-isothiocyanatophenyl)-1,3,4-
oxadiazol-2-ylsulfanyl]-1-ethanone (55)
Yield: 87%, mp: 119–120 °C. IR: 1603 (C@N), 2108 (NCS), 2566
(SCH2) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz): 3.98 (d, 2H,
Yield: 87%, mp: 165–166 °C. IR (Nujol) 1435 (C@N), 1678 (C@O),
J = 6.76 Hz, CH2-CH), 5.10–5.46 (m, 2H, CH2@CH), 5.75–6.17 (m,
1H, CH@CH2), 7.63 (d, 2H, J = 8.4 Hz, Ar), 7.98 (d, 2H, J = 8.4 Hz,
Ar). Anal. Calcd for C12H9N3OS2 (MW 275.35): C, 52.34; H, 3.29;
N, 15.26. Found: C, 52.36; H, 3.29; N, 15.28.
2120 (NCS), 2680 (SCH2) cmꢀ1 1H NMR (d ppm, DMSO-d6,
;
400 MHz): 5.16 (s, 2H, CH2), 7.51–8.13 (m, 8H, Ar). Anal. Calcd
for C17H10ClN3O2S2 (MW 387.86): C, 52.64; H, 2.60; N, 10.83.
Found: C, 52.69; H, 2.68; N, 10.89.

6802
F. Macaev et al. / Bioorg. Med. Chem. 19 (2011) 6792–6807
6.3. General procedure for the synthesis of amines 3–11, 20–47,
56–82
(s, 3H, Me), 7.15 (d, 2H, J = 7.6 Hz, MeC6H4N), 7.32 (d, 2H, J = 7.6 Hz,
MeC6H4N), 7.78 (d, 2H, J = 8.40 Hz, Ar), 7.81 (d, 2H, J = 8.40 Hz, Ar),
9.78 (s, 1H, NHp-tolyl), 9.84 (s, 1H, NHAr), 14.45 (s, 1H, SH). Anal.
Calcd for C16H14N4OS2 (MW 342.44): C, 56.12; H, 4.12; N, 16.36.
Found: C, 56.17; H, 4.17; N, 16.42.
To the solution of 1,3,4-oxadiazole (7 mmol) in benzene (30 ml),
the corresponding amine (8 mmol) was added. The reaction mix-
ture was refluxed for 3 h (TLC control), cooled to rt and precipitate
was filtered, washed with benzene, and dried.
6.3.8. Allylamino-4-(5-sulfanyl-1,3,4-oxadiazol-2-yl) anilinome-
thanethione (10)
6.3.1. Methylamino-4-(5-sulfanyl-1,3,4-oxadiazol-2-yl) anili-
nomethanethione (3)
Yield: 73%, mp: 185–187 °C. IR: 1330 (C@S), 1640 (C@N), 2657
(SH), 3090 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz): 4.17
;
Yield: 70%, mp: 246 °C. IR: 1315 (C@S), 1655 (C@N), 2678 (SH),
3089 (NH) cmꢀ1; 1H NMR (d ppm, DMSO-d6, 400 MHz): 2.99 (d, 3H,
J = 4.00 Hz, Me), 7.74 (d, 2H, J = 9.2 Hz, Ar), 7.79 (d, 2H, J = 9.2 Hz,
Ar), 7.86 (s, 1H, NHMe), 9.76 (s, 1H, NHAr), 14.37 (s, 1H, SH). Anal.
Calcd for C10H10N4OS2 (MW 266.34): C, 45.09; H, 3.78; N, 21.04.
Found: C, 45.14; H, 3.82; N, 21.11.
(s, 2H, CH2N), 5.13 (d, 1H, J = 10.00 Hz, CH2@CH), 5.24 (d, 1H,
J = 17.20 Hz, CH2@CH), 5.87–5.96 (m, 1H, CH@CH2), 7.52–7.98 (m,
5H, Ar, NHCH2), 9.76 (s, 1H, NHAr), 14.26 (s, 1H, SH). Anal. Calcd
for C12H12N4OS2 (MW 292.38): C, 49.29; H, 4.14; N, 19.16. Found:
C, 49.32; H, 4.08; N, 19.23.
6.3.9. Hydrazino-4-(5-sulfanyl-1,3,4-oxadiazol-2-yl) anilinome-
thanethione (11)
6.3.2. Amino-4-(5-sulfanyl-1,3,4-oxadiazol-2-yl) anilinome-
thanethione (4)
Yield: 68%, mp: 226–227 °C. IR: 1341 (C@S), 1616 (C@N), 2641
Yield: 72%, mp: 245–246 °C. IR: 1324 (C@S), 1622 (C@N), 2732
(SH), 3255 (NH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
(SH), 3374 (NH2) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz):
7.83–7.95 (m, 4H, Ar), 9.27 (s, 1H, NHNH2), 9.94 (s, 1H, NHAr),
14.15 (s, 1H, SH). Anal. Calcd for C9H9N5OS2 (MW 267.33): C,
40.44; H, 3.39; N, 26.20. Found: C, 40.51; H, 3.43; N, 26.26.
7.40–7.84 (m, 6H, Ar, NH2), 10.01 (s, 2H, NH, SH). Anal. Calcd for
C9H8N4OS2 (MW 252.32): C, 42.84; H, 3.20; N, 22.20. Found: C,
42.92; H, 3.25; N, 22.31.
6.3.10. Hydrazino-4-(5-methylsulfanyl-1,3,4-oxadiazol-2-yl)
anilinomethanethione (20)
6.3.3. Ethylamino-4-(5-sulfanyl-1,3,4-oxadiazol-2-yl)anilinome-
thanethione (5)
Yield: 74%, mp: 275 (dec)°C. IR: 1242 (SCH3), 1475 (C@S),
Yield: 75%, mp: 208–210 °C. IR: 1323 (C@S), 1547 (C@N), 2634
1618 (C@N), 3450 (NH2) cmꢀ1 1H NMR (d ppm, DMSO-d6,
;
(SH), 3059 (NH) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz): 1.20
400 MHz): 2.78 (s, 3H, Me), 7.85–7.99 (m, 4H, Ar), 9.21 (s, 1H,
NHNH2), 9.98 (s, 1H, NHAr). Anal. Calcd for C10H11N5OS2 (MW
281.36): C, 42.69; H, 3.94; N, 24.89. Found: C, 42.53; H, 3.88; N,
24.94.
(t, 3H, J = 7.2 Hz, Me), 3.53 (t, 2H, J = 6.00 Hz, CH2), 7.78 (d, 2H,
J = 10.00 Hz, Ar), 7.80 (d, 2H, J = 10.00 Hz, Ar), 8.01 (s, 1H, NHCH2),
9.87 (s, 1H, NHAr), 14.38 (s, 1H, SH). Anal. Calcd for C11H12N4OS2
(MW 280.37): C, 47.12; H, 4.31; N, 19.98. Found: C, 47.18; H,
4.37; N, 19.88.
6.3.11. 4-(5-Methylsulfanyl-1,3,4-oxadiazol-2-yl)anilino-4-tol-
uidinomethanethione (21)
6.3.4. Piperidino-4-(5-sulfanyl-1,3,4-oxadiazol-2-yl) anilinome-
thanethione (6)
Yield: 71%, mp: 198–200 °C. IR: 1179 (SCH3), 1370 (C@S), 1632
(C@N), 3098 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
Yield: 68%, mp: 182–183 °C. IR: 1355 (C@S), 1546 (C@N), 2635
2.34 (s, 3H, MeAr), 2.77 (s, 3H, SMe), 7.12 (d, 2H, J = 8.00 Hz,
MeC6H4NH), 7.36 (d, 2H, J = 8.00 Hz, MeC6H4NH), 7.78 (d, 2H,
J = 8.80 Hz, Ar), 7.88 (d, 2H, J = 8.80 Hz, Ar), 9.81 (s, 1H, NHp-tolyl),
9.89 (s, 1H, NHAr). Anal. Calcd for C17H16N4OS2 (MW 358.48): C,
57.28; H, 4.52; N, 15.72. Found: C, 57.33; H, 4.48; N, 15.81.
(SH), 3090 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz): 1.71
;
(s, 6H, 3CH2), 3.88 (s, 4H, N(CH2)2), 7.49 (d, 2H, J = 8.6 Hz, Ar), 7.79
(d, 2H, J = 8.6 Hz, Ar), 9.36 (s, 1H, NH), 14.35 (s, 1H, SH). Anal. Calcd
for C14H16N4OS2 (MW 320.43): C, 52.48; H, 5.03; N, 17.48. Found:
C, 52.52; H, 5.10; N, 17.53.
6.3.12. 4-(5-Methylsulfanyl-1,3,4-oxadiazol-2-yl) anilinomorp-
holinomethanethione (22)
6.3.5. 2-Hydroxyethylamino-4-(5-sulfanyl-1,3,4-oxadiazol-2-yl)
anilinomethanethione (7)
Yield: 69%, mp: 160–162 °C. IR: 1234 (SCH3), 1320 (C@S), 1631
Yield: 92%, mp: 190–191 °C. IR: 1275 (C@S), 1554 (C@N), 2734
(SH), 3441 (OH) cmꢀ1; 1H NMR (d ppm, DMSO-d6, 400 MHz): 3.58–
3.67 (m, 4H, (CH2)2NH), 4.79 (s, 1H, OH), 7.78–8.09 (m, 5H, Ar,
NHCH2), 9.97 (s, 2H, NHAr, SH). Anal. Calcd for C11H12N4O2S2
(MW 296.37): C, 44.58; H, 4.08; N, 18.90. Found: C, 44.64; H,
4.14; N, 18.97.
(C@N), 3158 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
2.77 (s, 3H, Me), 3.69 (t, 4H, J = 4.6 Hz, 2OCH2), 3.92 (t, 4H,
J = 4.6 Hz, N(CH2)2), 7.54 (d, 2H, J = 8.4 Hz, Ar), 7.87 (d, 2H,
J = 8.4 Hz, Ar), 9.49 (s, 1H, NH). Anal. Calcd for C14H16N4O2S2
(MW 336.43): C, 49.98; H, 4.79; N, 16.65. Found: C, 49.91; H,
4.82; N, 16.69.
6.3.6. N-(4-(5-Mercapto-1,3,4-oxadiazol-2-yl)phenyl)-2,2-dim-
ethylhydrazinecarbo thioamide (8)
6.3.13. 4-(5-Methylsulfanyl-1,3,4-oxadiazol-2-yl)anilino-4H-
1,2,4-triazol-4-yl-amino methanethione (23)
Yield: 84%, mp: 218–220 °C. IR: 1334 (C@S), 1546 (C@N), 2650
Yield: 86%, mp: 139–140 °C. IR: 1197 (SCH3), 1368 (C@S), 1647
(SH), 3078 (NH) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz): 2.18
(C@N), 3230 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
(s, 6H, 2Me), 7.38 (d, 2H, J = 8.4 Hz, Ar), 7.56 (d, 2H, J = 8.4 Hz, Ar),
9.13 (s, 1H, NHN), 9.75 (s, 1H, NHAr), 14.05 (s, 1H, SH). Anal. Calcd
for C11H12N4OS2 (MW 280.37): C, 47.12; H, 4.31; N, 19.98. Found:
C, 47.14; H, 4.37; N, 19.89.
2.80 (s, 3H, Me), 7.50 (d, 2H, J = 8.4 Hz, Ar), 7.79 (d, 2H, J = 8.4 Hz,
Ar), 8.65 (s, 2H, Tr), 10.08 (s, 1H, NHAr), 10.78 (s, 1H, NHTr). Anal.
Calcd for C12H11N7OS2 (MW 333.39): C, 43.23; H, 3.33; N, 29.41.
Found: C, 43.27; H, 3.41; N, 29.52.
6.3.7. 4-(5-Sulfanyl-1,3,4-oxadiazol-2-yl)anilino-4-toluidinome-
thanethione (9)
6.3.14. Amino-4-(5-methylsulfanyl-1,3,4-oxadiazol-2-yl) anil-
inomethanethione (24)
Yield: 88%, mp: 178–180 °C. IR: 1440 (C@S), 1645 (C@N), 2570
Yield: 81%, mp: 211–213 °C. IR: 1354 (SCH3), 1368 (C@S), 1667
(SH), 3058 (NH) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz): 2.33
(C@N), 3640 (NH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;

F. Macaev et al. / Bioorg. Med. Chem. 19 (2011) 6792–6807
6803
2.85 (s, 3H, Me), 7.19–8.05 (m, 6H, Ar, NH2), 9.94 (s, 1H, NH). Anal.
Calcd for C10H10N4OS2 (MW 266.34): C, 45.09; H, 3.78; N, 21.04.
Found: C, 45.13; H, 3.83; N, 21.11.
6.3.22. 2-(5–4-[2-Hydroxyethylamino(thioxo)
methylamino]phenyl-1,3,4-oxadiazol-2-ylsulfanyl)-
1-phenyl-1-ethanone (32)
Yield: 73%, mp: 167–169 °C. IR: 1473 (C@S), 1544 (C@N), 1675
(C@O), 3254 (OH) cmꢀ1; 1H NMR (d ppm, DMSO-d6, 400 MHz): 3.61
(s, 4H, (CH2)2NH), 4.72 (s, 1H, OH), 5.08 (s, 2H, SCH2), 7.50–8.07 (m,
10H, Ar, NHCH2), 9.82 (s, 1H, NHAr). Anal. Calcd for C19H18N4O3S2
(MW 414.50): C, 55.05; H, 4.38; N, 13.52. Found: C, 55.12; H,
4.42; N, 13.54.
6.3.15. 2-Hydroxyethylamino-4-(5-methylsulfanyl-1,3,4-
oxadiazol-2-yl)anilinomethanethione (25)
Yield: 64%, mp: 140–141 °C. IR: 1340 (SCH3), 1380 (C@S), 1635
(C@N), 3519 (OH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
2.78 (s, 3H, Me), 3.65 (s, 4H, (CH2)2NH), 4.83 (s, 1H, OH), 7.89–
7.95 (m, 5H, Ar, NHCH2), 9.91 (s, 1H, NHAr). Anal. Calcd for
C
12H14N4O2S2 (MW 310.40): C, 46.43; H, 4.55; N, 18.05. Found: C,
6.3.23. 4-(5-Allylsulfanyl-1,3,4-oxadiazol-2-yl)anilino-2-
hydroxyethylaminomethane-thione (33)
46.47; H, 4.61; N, 18.12.
Yield: 81%, mp: 121–122 °C. IR: 1313 (C@S), 1533 (C@N), 2726
6.3.16. 2-Hydroxyethylamino-4-[5-(4-pyridylmethylsulfanyl)-
1,3,4-oxadiazol-2-yl]anilinomethanethione (26)
(SCH2), 3342 (OH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
3.54–3.59 (m, 4H, (CH2)2NH), 3.95 (d, 2H, J = 6.86 Hz, CH2-CH),
4.91 (s, 1H, OH), 5.11–5.43 (m, 2H, CH2@CH), 5.76–6.17 (m, 1H,
CH@CH2), 7.70–8.04 (m, 5H, Ar, NHCH2), 9.97 (s, 1H, NHAr). Anal.
Calcd for C14H16N4O2S2 (MW 336.43): C, 49.98; H, 4.79; N, 16.65.
Found: C, 49.93; H, 4.82; N, 16.71.
Yield: 72%, mp: 168–169 °C. IR: 1475 (C@S), 1606 (C@N), 2727
(SCH2), 3500 (OH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
3.53–3.58 (m, 4H, (CH2)2NH), 4.57 (s, 1H, OH), 4.87 (s, 2H, SCH2),
7.35–8.03 (m, 9H, Ar, NHCH2), 9.84 (s, 1H, NHAr). Anal. Calcd for
C17H17N5O2S2 (MW 387.48): C, 52.69; H, 4.42; N, 18.07. Found: C,
52.73; H, 4.46; N, 18.12.
6.3.24. 4-(5-Benzylsulfanyl-1,3,4-oxadiazol-2-yl)anilino-2-
hydroxyethylaminomethane-thione (34)
6.3.17. 2–5-[4-Amino(thioxo)methylaminophenyl]-1,3,4-
oxadiazol-2-ylsulfanyl-1-phenyl-1-ethanone (27)
Yield: 84%, mp: 139–140 °C. IR: 1320 (C@S), 1611 (C@N), 2879
(SCH2), 3345 (OH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
Yield: 86%, mp: 207–209 °C. IR: 1468 (C@S), 1662 (C@N), 1677
3.52–3.58 (m, 4H, (CH2)2NH), 4.57 (s, 1H, OH), 5.00 (s, 2H, SCH2),
6.99–8.19 (m, 10H, Ar, NHCH2), 9.83 (s, 1H, NHAr). Anal. Calcd for
(C@O), 3347 (NH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
5.18 (s, 2H, CH2), 7.38–8.21 (m, 11H, Ar, NH2), 9.93 (s, 1H, NH).
Anal. Calcd for C17H14N4O2S2 (MW 370.45): C, 55.12; H, 3.81; N,
15.12. Found: C, 55.17; H, 3.85; N, 15.17.
C18H18N4O2S2 (MW 386.49): C, 55.94; H, 4.69; N, 14.50. Found: C,
55.97; H, 4.72; N, 14.54.
6.3.25. 4-(5-Allylsulfanyl-1,3,4-oxadiazol-2-yl)anilino-ami-
nomethanethione (35)
6.3.18. Amino-4-[5-(2-pyrimidinylsulfanyl)-1,3,4-oxadiazol-2-
yl]anilinomethanethione (28)
Yield: 79%, mp: 173–174 °C. IR: 1347 (C@S), 1657 (C@N), 2729
Yield: 78%, mp: 214–215 °C. IR: 1372 (C@S), 1630 (C@N), 3150
(SCH2), 3337 (NH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
(NH), 3320 (NH2) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz):
3.94 (d, 2H, J = 6.81 Hz, CH2-CH), 5.07–5.41 (m, 2H, CH2@CH),
5.74–6.24 (m, 1H, CH@CH2), 7.33–7.95 (m, 6H, Ar, NH2), 10.05 (s,
1H, NH). Anal. Calcd for C12H12N4OS2 (MW 292.38): C, 49.29; H,
4.14; N, 19.16. Found: C, 49.32; H, 4.17; N, 19.21.
7.25–8.75 (m, 9H, Ar, NH2), 9.92 (s, 1H, NH). Anal. Calcd for
13H10N6OS2 (MW 330.39): C, 47.26; H, 3.05; N, 25.44. Found: C,
C
47.29; H, 3.11; N, 25.48.
6.3.19. 1-(4-Fluorophenyl)-2-(5–4-[2-
6.3.26. 1-(2,4-Dichlorophenyl)-2-(5-4-[2-
hydroxyethylamino(thioxo)methylamino]phenyl-1,3,4-
oxadiazol-2-ylsulfanyl)-1-ethanone (29)
hydroxyethylamino(thioxo)methylamino]-phenyl-1,3,4-
oxadiazol-2-ylsulfanyl)-1-ethanone (36)
Yield: 85%, mp: 180–182 °C. IR: 1338 (C@S), 1541 (C@N),
Yield: 71%, mp: 163–164 °C. IR: 1469(C@S), 1541 (C@N), 1674
1676 (C@O), 3225 (OH) cmꢀ1
;
1H NMR (d ppm, DMSO-d6,
(C@O), 3469 (OH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
400 MHz): 3.52–3.59 (m, 4H, (CH2)2NH), 4.88 (s, 1H, OH), 5.16 (s,
2H, SCH2), 7.34–7.65 (m, 5H, Ar, NHCH2), 8.07–8.25 (m, 4H,
Ar), 9.84 (s, 1H, NHAr). Anal. Calcd for C19H17FN4O3S2 (MW
432.49): C, 52.76; H, 3.96; N, 12.95. Found: C, 52.79; H, 3.92; N,
12.89.
3.55–3.58 (m, 4H, (CH2)2NH), 4.88 (s, 1H, OH), 5.01 (s, 2H, SCH2),
7.25–8.01 (m, 8H, Ar, NHCH2), 9.82 (s, 1H, NHAr). Anal. Calcd for
C19H16Cl2N4O3S2 (MW 483.39): C, 47.21; H, 3.34; N, 11.59. Found:
C, 47.26; H, 3.38; N, 11.63.
6.3.27. Amino-4-[5-(4-pyridylmethylsulfanyl)-1,3,4-oxadiazol-
2-yl]anilinomethanethione (37)
6.3.20. Amino-4-(5-benzylsulfanyl-1,3,4-oxadiazol-2-yl)
anilinomethanethione (30)
Yield: 82%, mp: 203–204 °C. IR: 1473 (C@S), 1669 (C@N), 2742
Yield: 77%, mp: 179–180 °C. IR: 1469 (C@S), 1656 (C@N), 2727
(SCH2), 3343 (NH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
(SCH2), 3330 (NH2) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz):
4.55 (s, 2H, CH2), 7.91–8.55 (m, 10H, Ar, NH2), 9.93 (s, 1H, NH).
Anal. Calcd for C15H13N5OS2 (MW 343.43): C, 52.46; H, 3.82; N,
20.39. Found: C, 52.49; H, 3.87; N, 20.43.
4.57 (s, 2H, CH2), 6.98–8.05 (m, 11H, Ar, NH2), 9.93 (s, 1H, NH).
Anal. Calcd for C16H14N4OS2 (MW 342.44): C, 56.12; H, 4.12; N,
16.36. Found: C, 56.15; H, 4.17; N, 16.38.
6.3.28. 2-Hydroxyethylamino-4-[5-(2-pyrimidinylsulfanyl)-
1,3,4-oxadiazol-2-yl]anilinomethanethione (38)
6.3.21. 2–5-[4-Amino(thioxo)methylaminophenyl]-1,3,4-
oxadiazol-2-ylsulfanyl-1-(2,4-dichlorophenyl)-1-ethanone (31)
Yield: 79%, mp: 170–171 °C. IR: 1477 (C@S), 1620 (C@N), 1664
Yield: 78%, mp: 188–189 °C. IR: 1379 (C@S), 1613 (C@N), 3182
(NH), 3462 (OH) cmꢀ1; 1H NMR (d ppm, DMSO-d6, 400 MHz): 3.50–
3.54 (m, 4H, (CH2)2NH), 4.89 (s, 1H, OH), 7.34–8.45 (m, 8H, Ar,
NHCH2), 9.83 (s, 1H, NHAr). Anal. Calcd for C15H14N6O2S2 (MW
374.44): C, 48.11; H, 3.77; N, 22.44. Found: C, 48.15; H, 3.79; N,
22.48.
(C@O), 3448 (NH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
5.01 (s, 2H, CH2), 7.38–8.11 (m, 9H, Ar, NH2), 9.93 (s, 1H, NH). Anal.
Calcd for C17H12Cl2N4O2S2 (MW 439.34): C, 46.47; H, 2.75; N,
12.75. Found: C, 46.52; H, 2.79; N, 12.79.

6804
F. Macaev et al. / Bioorg. Med. Chem. 19 (2011) 6792–6807
6.3.29. Allylamino-3-(5-sulfanyl-1,3,4-oxadiazol-2-yl) anili-
nomethanethione (39)
6.3.36. N-(3-(5-Mercapto-1,3,4-oxadiazol-2-yl)phenyl)-2,2-
dimethylhydrazinecarbothio amide (46)
Yield: 71%, mp: 170–171 °C. IR: 1320 (C@S), 1634 (C@N), 2655
Yield: 82%, mp: 197–198 °C. IR: 1335 (C@S), 1547 (C@N),
(SH), 3180 (NH) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz): 3.90
2590 (SH), 3135 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6,
;
(s, 2H, CH2N), 5.16 (d, 1H, J = 9.8 Hz, CH2@CH), 5.22 (d, 1H,
J = 16.80 Hz, CH2@CH), 5.79–6.20 (m, 1H, CH@CH2), 7.48–7.86 (m,
5H, Ar, NHCH2), 9.81 (s, 1H, NHAr), 14.22 (s, 1H, SH). Anal. Calcd
for C12H12N4OS2 (MW 292.38): C, 49.29; H, 4.14; N, 19.16. Found:
C, 49.33; H, 4.07; N, 19.24.
400 MHz): 3.35 (s, 6H, 2Me), 7.55–7.76 (m, 4H, Ar), 8.19 (s, 1H,
NHN), 9.88 (s, 1H, NHAr), 14.27 (s, 1H, SH). Anal. Calcd for
C11H12N4OS2 (MW 295.38): C, 47.12; H, 4.31; N, 19.98. Found: C,
47.18; H, 4.34; N, 19.87.
6.3.37. 3-(5-Sulfanyl-1,3,4-oxadiazol-2-yl)anilino-4-
toluidinomethanethione (47)
6.3.30. N-(3-(5-Mercapto-1,3,4-oxadiazol-2-yl)phenyl)-2-
(propan-2-ylidene)hydrazine-carbothioamide (40)
Yield: 81%, mp: 168–170 °C. IR: 1297 (C@S), 1634 (C@N), 2670
Yield: 67%, mp: 203–205 °C. IR: 1483 (C@S), 1647 (C@N), 2720
(SH), 3070 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz): 2.32
;
(SH), 3223 (NH) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz): 2.04
(s, 3H, Me), 7.19–7.57 (m, 4H, MeC6H4NH), 7.76–8.01 (m, 4H, Ar),
9.76 (s, 1H, NHp-tolyl), 9.84 (s, 1H, NHAr), 14.32 (s, 1H, SH). Anal.
Calcd for C16H14N4OS2 (MW 342.44): C, 56.12; H, 4.12; N, 16.36.
Found: C, 56.20; H, 4.21; N, 16.43.
(s, 3H, Me), 2.07 (s, 3H, Me), 7.47 (t, 1H, J = 8.00 Hz, Ar), 7.68 (d, 1H,
J = 8.00 Hz, Ar), 7.91 (d, 1H, J = 8.00 Hz, Ar), 8.27 (s, 1H, J = 8.00 Hz,
Ar), 9.76 (s, 1H, NHN), 10.36 (s, 1H, NHAr), 14.44 (s, 1H, SH). Anal.
Calcd for C12H13N5OS2 (MW 307.39): C, 46.89; H, 4.26; N, 22.78.
Found: C, 46.97; H, 4.33; N, 22.85.
6.3.38. 1-(4-Fluorophenyl)-2-(5–3-[2-
hydroxyethylamino(thioxo)methylamino]phenyl-1,3,4-
oxadiazol-2-ylsulfanyl)-1-ethanone (56)
6.3.31. N-(3-(5-Mercapto-1,3,4-oxadiazol-2-yl)phenyl)-2-(1-
phenylethylidene)hydrazine carbothioamide (41)
Yield: 75%, mp: 145–146 °C. IR: 1381 (C@S), 1640 (C@N), 1676
Yield: 75%, mp: 212–214 °C. IR: 1370 (C@S), 1647 (C@N), 2655
(C@O), 3480 (OH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
(SH), 3076 (NH) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz): 2.43
3.61–3.77 (m, 4H, (CH2)2NH), 4.68 (s, 1H, OH), 5.19 (s, 2H, SCH2),
7.35–8.29 (m, 9H, Ar, NHCH2), 11.31 (s, 1H, NHAr). Anal. Calcd for
(s, 3H, Me), 7.35–7.41 (m, 3H, Ar), 7.51 (t, 1H, J = 8.00 Hz, Ar), 7.72
(d, 1H, J = 7.60 Hz, Ar), 7.89 (d, 1H, J = 9.20 Hz, Ar), 7.91 (t, 1H,
J = 1.60 Hz, Ar), 7.93 (d, 1H, J = 2.40 Hz, Ar), 8.30 (t, 1H,
J = 1.60 Hz, Ar), 10.03 (s, 1H, NHN), 10.63 (s, 1H, NHAr), 14.50 (s,
1H, SH). Anal. Calcd for C17H15N5OS2 (MW 369.46): C, 55.26; H,
4.09; N, 18.96. Found: C, 55.34; H, 4.14; N, 18.87.
C19H17FN4O3S2 (MW 432.49): C, 52.76; H, 3.96; N, 12.95. Found:
C, 52.82; H, 3.94; N, 12.89.
6.3.39. 2–5-[3-Dimethylamino(thioxo)methylaminophenyl]-
1,3,4-oxadiazol-2-ylsulfanyl-1-(2-naphthyl)-1-ethanone (57)
Yield: 87%, mp: 176–178 °C. IR: 1365 (C@S), 1615 (C@N),
6.3.32. 3-(5-Sulfanyl-1,3,4-oxadiazol-2-yl)anilino-4H-1,2,4-
triazol-4-ylaminomethane thione (42)
1685 (C@O), 3189 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6,
;
400 MHz): 3.40 (s, 6H, 2Me), 5.00 (s, 2H, CH2) 7.36–8.25 (m,
11H, Ar), 8.62 (s, 1H, NH). Anal. Calcd for C23H20N4O2S2 (MW
448.56): C, 61.58; H, 4.49; N, 12.49. Found: C, 61.65; H, 4.44; N,
12.52.
Yield: 78%, mp: 211–213 °C. IR: 1368 (C@S), 1645 (C@N), 2670
(SH), 3190 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz): 7.53
;
(t, 1H, J = 7.20 Hz, Ar), 7.71 (d, 2H, J = 6.40 Hz, Ar), 8.21 (s, 1H, Ar),
8.73 (s, 2H, Tr), 9.98 (s, 1H, NHAr), 10.87 (s, 1H, NHTr), 14.18 (s, 1H,
SH). Anal. Calcd for C11H9N7OS2 (MW 319.37): C, 41.37; H, 2.84; N,
30.70. Found: C, 41.41; H, 2.76; N, 30.77.
6.3.40. 2-(5–3-[2-Hydroxyethylamino(thioxo)methylamino]
phenyl-1,3,4-oxadiazol-2-ylsulfanyl)-1-(2-naphthyl)-1-
ethanone (58)
6.3.33. Piperidino-3-(5-sulfanyl-1,3,4-oxadiazol-2-yl) anili-
nomethanethione (43)
Yield: 77%, mp: 153–154 °C. IR: 1472 (C@S), 1534 (C@N), 1675
(C@O), 3470 (OH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
Yield: 81%, mp: 186–188 °C. IR: 1345 (C@S), 1546 (C@N), 2620
3.53–3.59 (m, 4H, (CH2)2NH), 4.87 (s, 1H, OH), 5.31 (s, 2H, SCH2),
7.37–8.22 (m, 12H, Ar, NHCH2), 9.82 (s, 1H, NHAr). Anal. Calcd for
(SH), 3180 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz): 1.68
;
(s, 6H, 3CH2), 3.76 (s, 4H, N(CH2)2), 7.35–7.98 (m, 4H, Ar), 9.48 (s,
1H, NH), 14.05 (s, 1H, SH). Anal. Calcd for C14H16N4OS2 (MW
320.43): C, 52.48; H, 5.03; N, 17.48. Found: C, 52.55; H, 5.12; N,
17.51.
C23H20N4O3S2 (MW 464.56): C, 59.46; H, 4.34; N, 12.06. Found: C,
59.51; H, 4.27; N, 12.12.
6.3.41. 1-(2,4-Dichlorophenyl)-2-(5–3-[2-
hydroxyethylamino(thioxo)methylamino]-phenyl-1,3,4-
oxadiazol-2-ylsulfanyl)-1-ethanone (59)
6.3.34. Hydrazino-3-(5-sulfanyl-1,3,4-oxadiazol-2-yl) anili-
nomethanethione (44)
Yield: 78%, mp: 83–85 °C. IR: 1457 (C@S), 1535 (C@N), 1654
Yield: 84%, mp: 186–187 °C. IR: 1345 (C@S), 1615 (C@N), 2729
(SH), 2862 (NH) cmꢀ1; 1H NMR (d ppm, DMSO-d6, 400 MHz): 7.54–
7.96 (m, 4H, Ar), 7.7 (d, 2H, J = 6.9 Hz, NH2NH), 9.31 (s, 1H, NHNH2),
9.92 (s, 1H, NHAr), 14.21 (s, 1H, SH). Anal. Calcd for C9H9N5OS2
(MW 267.33): C, 40.44; H, 3.39; N, 26.20. Found: C, 40.43; H,
3.43; N, 26.27.
(C@O), 3560 (OH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
3.53–3.59 (m, 4H, (CH2)2NH), 4.86 (s, 1H, OH), 5.00 (s, 2H, SCH2),
7.38–8.21 (m, 8H, Ar, NHCH2), 9.82 (s, 1H, NHAr). Anal. Calcd for
C19H16Cl2N4O3S2 (MW 483.39): C, 47.21; H, 3.34; N, 11.59. Found:
C, 47.24; H, 3.37; N, 11.62.
6.3.35. Amino-3-(5-sulfanyl-1,3,4-oxadiazol-2-yl) anilinome-
thanethione (45)
6.3.42. 2–5-[3-Amino(thioxo)methylaminophenyl]-1,3,4-
oxadiazol-2-ylsulfanyl-1-(2,4-dichlorophenyl)-1-ethanone (60)
Yield: 64%, mp: 200–202 °C. IR: 1475 (C@S), 1618 (C@N), 1662
Yield: 76%, mp: 195–196 °C. IR: 1351 (C@S), 1606 (C@N), 2726
(SH), 3450 (NH) cmꢀ1; 1H NMR (d ppm, DMSO-d6, 400 MHz): 7.22–
7.87 (m, 6H, Ar, NH2), 9.93 (s, 2H, NH, SH). Anal. Calcd for
C9H8N4OS2 (MW 252.32): C, 42.84; H, 3.20; N, 22.20. Found: C,
42.88; H, 3.24; N, 22.16.
(C@O), 3450 (NH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
5.01 (s, 2H, CH2), 7.36–8.15 (m, 9H, Ar, NH2), 9.93 (s, 1H, NH). Anal.
Calcd for C17H12Cl2N4O2S2 (MW 439.34): C, 46.47; H, 2.75; N,
12.75. Found: C, 46.49; H, 2.79; N, 12.72.

F. Macaev et al. / Bioorg. Med. Chem. 19 (2011) 6792–6807
6805
6.3.43. 2–5-[3-Amino(thioxo)methylaminophenyl]-1,3,4-
oxadiazol-2-ylsulfanyl-1-(4-chlorophenyl)-1-ethanone (61)
Yield: 81%, mp: 193–194 °C. IR: 1460 (C@S), 1579 (C@N), 1665
Anal. Calcd for C17H13FN4O2S2 (MW 388.44): C, 52.56; H, 3.37; N,
14.42. Found: C, 52.59; H, 3.38; N, 14.48.
(C@O), 3445 (NH2) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz):
6.3.51. 2-(5–3-[2-
5.15 (s, 2H, CH2), 7.35–7.72 (m, 6H, Ar, NH2), 8.00–8.13 (m, 4H,
Ar), 9.92 (s, 1H, NH). Anal. Calcd for 17H13ClN4O2S2 (MW
404.89): C, 50.43; H, 3.24; N, 13.84. Found: C, 50.47; H, 3.27; N,
13.89.
Hydroxyethylamino(thioxo)methylamino]phenyl-1,3,4-
oxadiazol-2-ylsulfanyl)-1-phenyl-1-ethanone (69)
Yield: 89%, mp: 150–152 °C. IR: 1455 (C@S), 1490 (C@N), 1675
C
(C@O), 3256 (OH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
3.53–3.56 (m, 4H, (CH2)2NH), 4.90 (s, 1H, OH), 5.18 (s, 2H, SCH2),
7.47–8.19 (m, 10H, Ar, NHCH2), 9.84 (s, 1H, NHAr). Anal. Calcd for
6.3.44. 2–5-[3-Amino(thioxo)methylaminophenyl]-1,3,4-
oxadiazol-2-ylsulfanyl-1-phenyl-1-ethanone (62)
C19H18N4O3S2 (MW 414.50): C, 55.05; H, 4.38; N, 13.52. Found: C,
Yield: 74%, mp: 180–182 °C. IR: 1476 (C@S), 1665 (C@N), 1657
55.12; H, 4.42; N, 13.55.
(C@O), 3350 (NH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
5.18 (s, 2H, CH2), 7.36–8.14 (m, 11H, Ar, NH2), 9.92 (s, 1H, NH).
Anal. Calcd for C17H14N4O2S2 (MW 370.45): C, 55.12; H, 3.81; N,
15.12. Found: C, 55.16; H, 3.88; N, 15.16.
6.3.52. 2–5-[3-Dimethylamino(thioxo)methylaminophenyl]-
1,3,4-oxadiazol-2-ylsulfanyl-1-(4-methylphenyl)-1-ethanone
(70)
Yield: 90%, mp: 173–175 °C. IR: 1384 (C@S), 1645 (C@N), 1467
(C@O), 3240 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
6.3.45. 2–5-[3-Amino(thioxo)methylaminophenyl]-1,3,4-
oxadiazol-2-ylsulfanyl-1-(4-bromophenyl)-1-ethanone (63)
Yield: 89%, mp: 187–188 °C. IR: 1467 (C@S), 1598 (C@N), 1645
2.32 (s, 3H, MeAr), 3.41 (s, 6H, Me2N), 5.00 (s, 2H, SCH2), 7.41–
8.15 (m, 8H, Ar), 8.63 (s, 1H, NH). Anal. Calcd for C20H20N4O2S2
(MW 412.53): C, 58.23; H, 4.89; N, 13.58. Found: C, 58.26; H,
4.93; N, 13.54.
(C@O), 3045 (NH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
5.16 (s, 2H, CH2), 7.36–8.13 (m, 10H, Ar, NH2), 9.94 (s, 1H, NH).
Anal. Calcd for C17H13BrN4O2S2 (MW 449.34): C, 45.44; H, 2.92;
N, 12.47. Found: C, 45.48; H, 2.96; N, 12.51.
6.3.53. 2–5-[3-Amino(thioxo)methylaminophenyl]-1,3,4-
oxadiazol-2-ylsulfanyl-1-(2-naphthyl)-1-ethanone (71)
Yield: 82%, mp: 193–194 °C. IR: 1400 (C@S), 1645 (C@N), 1565
6.3.46. 2–5-[3-Dimethylamino(thioxo)methylaminophenyl]-
1,3,4-oxadiazol-2-ylsulfanyl-1-phenyl-1-ethanone (64)
Yield: 80%, mp: 166–168 °C. IR: 1377 (C@S), 1656 (C@N), 1445
(C@O), 3070 (NH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
(C@O), 3268 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
5.31 (s, 2H, CH2), 7.36–8.22 (m, 13H, Ar, NH2), 9.92 (s, 1H, NH).
Anal. Calcd for C21H16N4O2S2 (MW 420.51): C, 59.98; H, 3.84; N,
13.32. Found: C, 59.93; H, 3.86; N, 13.38.
3.40 (s, 6H, 2Me), 5.01 (s, 2H, CH2) 7.25–8.00 (m, 9H, Ar), 8.61 (s,
1H, NH). Anal. Calcd for C19H18N4O2S2 (MW 398.50): C, 57.26; H,
4.55; N, 14.06. Found: C, 57.28; H, 4.52; N, 14.11.
6.3.54. 6.3.54.2-Hydroxyethylamino-3-(5-phenethylsulfanyl-
1,3,4-oxadiazol-2-yl)anilinemethane thione (72)
6.3.47. Amino-3-(5-phenethylsulfanyl-1,3,4-oxadiazol-2-yl)
anilinomethanethione (65)
Yield: 85%, mp: 142–144 °C. IR: 1465 (C@S), 1590 (C@N), 2547
(SCH2), 3270 (OH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
Yield: 78%, mp: 127–128 °C. IR: 1465 (C@S), 1765 (C@N), 2738
(SCH2), 3430 (NH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
3.01–3.18 (m, 4H, (CH2)2Ar), 3.47–3.65 (m, 5H, HO(CH2)2), 7.25–
7.76 (m, 10H, Ar, NHCH2), 8.25 (s, 1H, NHAr). Anal. Calcd for
3.08 (t, 2H, J = 7.46 Hz, CH2S), 3.57 (t, 2H, J = 7.46 Hz, CH2Ar),
7.25–8.17 (m, 11H, Ar, NH2), 9.95 (s, 1H, NH). Anal. Calcd for
C19H20N4O2S2 (MW 400.52): C, 56.98; H, 5.03; N, 13.99. Found: C,
56.92; H, 5.11; N, 13.92.
C17H16N4OS2 (MW 356.47): C, 57.28; H, 4.52; N, 15.72. Found: C,
57.32; H, 4.54; N, 15.76.
6.3.55. Amino-3-(5-methylsulfanyl-1,3,4-oxadiazol-2-
yl)anilinomethanethione (73)
6.3.48. 1-(4-Bromophenyl)-2-(5–3-[2-
hydroxyethylamino(thioxo)methylamino]phenyl-1,3,4-
oxadiazol-2-ylsulfanyl)-1-ethanone (66)
Yield: 80%, mp: 221 °C. IR: 1240 (SCH3), 1348 (C@S), 1615
(C@N), 3490 (NH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
2.75 (s, 3H, Me), 7.33–7.98 (m, 6H, Ar, NH2), 9.93 (s, 1H, NH). Anal.
Calcd for C10H10N4OS2 (MW 266.34): C, 45.09; H, 3.78; N, 21.04.
Found: C, 45.13; H, 3.68; N, 21.12.
Yield: 84%, mp: 162–164 °C. IR: 1367 (C@S), 1541 (C@N), 1644
(C@O), 3290 (OH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
3.52–3.58 (m, 4H, (CH2)2NH), 4.89 (s, 1H, OH), 5.16 (s, 2H, SCH2),
7.56–8.19 (m, 9H, Ar, NH CH2), 9.84 (s, 1H, NHAr). Anal. Calcd for
C19H17BrN4O3S2 (MW 493.40): C, 46.25; H, 3.47; N, 11.36. Found:
C, 46.27; H, 3.51; N, 11.42.
6.3.56. 2-Hydroxyethylamino-3-(5-methylsulfanyl-1,3,4-
oxadiazol-2-yl)anilinomethane thione (74)
Yield: 78%, mp: 150–153 °C. IR: 1356 (SCH3), 1376 (C@S), 1645
(C@N), 3520 (OH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
6.3.49. 1-(4-Chlorophenyl)-2–5-[3-
dimethylamino(thioxo)methylaminophenyl]-1,3,4-oxadiazol-2-
ylsulfanyl-1-ethanone (67)
2.65 (s, 3H, Me), 3.61 (s, 4H, (CH2)2NH), 4.88 (s, 1H, OH), 7.45–
7.56 (m, 5H, Ar, NHCH2), 9.90 (s, 1H, NHAr). Anal. Calcd for
C12H14N4O2S2 (MW 310.40): C, 46.43; H, 4.55; N, 18.05. Found: C,
Yield: 92%, mp: 158–160 °C. IR: 1384 (C@S), 1615 (C@N), 1385
(C@O), 3170 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
46.55; H, 4.59; N, 18.12.
3.41 (s, 6H, 2Me), 5.00 (s, 2H, SCH2), 7.38–8.02 (m, 8H, Ar), 8.60
(s, 1H, NH). Anal. Calcd for C19H17ClN4O2S2 (MW 432.95): C,
52.71; H, 3.96; N, 12.94. Found: C, 52.75; H, 3.92; N, 12.97.
6.3.57. 3-(5-Methylsulfanyl-1,3,4-oxadiazol-2-yl)anilino-4H-
1,2,4-triazol-4-ylamino methanethione (75)
Yield: 69%, mp: 182–184 °C. IR: 1210 (SCH3), 1375 (C@S), 1645
(C@N), 3240 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
6.3.50. 2–5-[3-Amino(thioxo)methylaminophenyl]-1,3,4-
oxadiazol-2-ylsulfanyl-1-(4-fluorophenyl)-1-ethanone (68)
Yield: 87%, mp: 190–192 °C. IR: 1471 (C@S), 1610 (C@N), 1648
2.78 (s, 3H, Me), 7.55 (t, 1H, J = 7.60 Hz, Ar), 7.76 (d, 2H,
J = 6.80 Hz, Ar), 8.15 (s, 1H, Ar), 8.68 (s, 2H, Tr), 10.63 (s, 1H, NHAr),
11.08 (s, 1H, NHTr). Anal. Calcd for C12H11N7OS2 (MW 333.39): C,
43.23; H, 3.33; N, 29.41. Found: C, 43.27; H, 3.41; N, 29.47.
(C@O), 3303 (NH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
5.17 (s, 2H, CH2), 7.31–8.25 (m, 10H, Ar, NH2), 9.94 (s, 1H, NH).

6806
F. Macaev et al. / Bioorg. Med. Chem. 19 (2011) 6792–6807
6.3.58. Hydrazino-3-(5-methylsulfanyl-1,3,4-oxadiazol-2-yl)
anilinomethanethione (76)
broth microdilution assay, the Microplate Alamar Blue Assay
(MABA) according to the reported method.26
Yield: 72%, mp: 141–143 °C. IR: 1234 (SCH3), 1475 (C@S), 1625
(C@N), 3390 (NH2) cmꢀ1
;
1H NMR (d ppm, DMSO-d6, 400 MHz):
Acknowledgments
2.76 (s, 3H, Me), 7.56–7.89 (m, 4H, Ar), 7.89 (d, 2H, J = 6.8 Hz,
NH2NH), 9.36 (s, 1H, NHNH2), 10.15 (s, 1H, NHAr). Anal. Calcd for
The authors gratefully acknowledge funding through a grant
from the Moldavian-US Bilateral Grants Program of the US Civilian
Research and Development Foundation (Grant MC2-3007). We also
acknowledge the Tuberculosis Antimicrobial Acquisition and Coor-
dinating Facility provided through the US National Institutes of
Health (Contract N01-AI-95364) for providing data on the antitu-
bercular activity.
C10H11N5OS2 (MW 281.36): C, 42.69; H, 3.94; N, 24.89. Found: C,
42.66; H, 3.91; N, 24.77.
6.3.59. 3-(5-Methylsulfanyl-1,3,4-oxadiazol-2-yl)anilino-4-
toluidinomethanethione (77)
Yield: 74%, mp: 173–175 °C. IR: 1167 (SCH3), 1365 (C@S), 1645
(C@N), 3090 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
2.35 (s, 3H, MeAr), 2.78 (s, 3H, SMe), 7.25–7.68 (m, 4H, MeC6H4NH),
7.81–8.12 (m, 4H, Ar), 9.84 (s, 1H, NHp-tolyl), 9.96 (s, 1H, NHAr).
Anal. Calcd for C17H16N4OS2 (MW 356.47): C, 57.28; H, 4.52; N,
15.72. Found: C, 57.31; H, 4.58; N, 15.79.
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.bmc.2011.09.038. These data
include MOL files and InChiKeys of the most important compounds
described in this article.
6.3.60. 3-(5-Methylsulfanyl-1,3,4-oxadiazol-2-yl)anilino-
morpholinomethanethione (78)
Yield: 79%, mp: 134–136 °C. IR: 1225 (SCH3), 1346 (C@S), 1638
References and notes
(C@N), 3192 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
2.75 (s, 3H, Me), 3.67 (t, 4H, J = 4.8 Hz, 2OCH2), 3.95 (t, 4H,
J = 4.8 Hz, N(CH2)2), 7.46–7.81 (m, 4H, Ar), 9.54 (s, 1H, NH). Anal.
Calcd for C14H16N4O2S2 (MW 336.43): C, 49.98; H, 4.79; N, 16.65.
Found: C, 49.86; H, 4.75; N, 16.77.
1. Janin, Y. L. Bioorg. Med. Chem. 2007, 15, 2479.
2. Murray; Christopher, J. L.; Lopez; Alan, D. The Global Burden of Disease: A
Comprehensive Assessment of Mortality and Disability from Diseases, Injuries and
Risk Factors in 1990 and Projected to 2020: Summary; WHO: Switzerland, 1996.
3. Narain, J. P. In Tuberculosis–Epidemiology and Control; World Health
Organization: New Delhi, India, 2002; Vol. 248, pp 15–18.
4. Fattorini, L.; Iona, E.; Ricci, M. L.; Thoresen, O. F.; Orrù, G.; Oggioni, M. R.;
Tortoli, E.; Piersimoni, C.; Chiaradonna, P.; Tronci, M.; Pozzi, G.; Orefici, G.
Microb. Drug Resist. 1999, 5, 265.
6.3.61. 3-(5-Methylsulfanyl-1,3,4-oxadiazol-2-yl)anilino-
methanethione (79)
Yield: 65%, mp: 161–162 °C. IR: 1335 (C@S), 1545 (C@N), 2600
5. Van Rie, A.; Warren, R. M.; Beyers, N.; Gie, R. P.; Classen, C. N.; Richardson, M.;
Sampson, S. L.; Victor, T. C.; Van Helden, P. D. J. Infect. Dis 1999, 180, 1608.
6. Enwere, G. C.; Ota, M. O.; Obaro, S. K. Ann. Trop. Med. Parasitol. 1999, 93, 669.
7. Smith, K.; Bender, J.; Osterholm, M.; Nachamkin, I.; Blaser, M. Campylobacter;
American Society for Microbiology: Washingdon, DC, 2000. pp 483–495.
8. World Health Organization. In Antituberculosis Drug Resistance in the World; The
WHO/IUALTD Global Project on Antituberculosis Drug Resistance Surveillance.
Switzerland, 1997.
(SH), 3197 (N(CH3)2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
2.12 (s, 6H, 2Me), 2.58 (s, 3H, SMe), 7.38–7.57 (m, 4H, Ar), 9.25 (s,
1H, NHN), 9.90 (s, 1H, NHAr). Anal. Calcd for C12H14N4OS2 (MW
294.40):C, 48.96;H, 4.79;N, 19.03. Found:C, 48.89;H, 4.82;N, 19.12.
6.3.62. 1-(2,4-Dichlorophenyl)-2,5-[3-
dimethylamino(thioxo)methylaminophenyl]-1,3,4-oxadiazol-2-
ylsulfanyl-1-ethanone (80)
9. Ballell, L.; Field, R. A.; Duncan, K.; Young, R. J. Antimicrob. Agents Chemother.
2005, 49, 2153.
10. Sutherland, H. S.; Blaser, A.; Kmentova, I.; Franzblau, S. G.; Wan, B.; Wang, Y.; Ma,
Z.; Palmer, B. D.; Denny, W. A.; Thompson, A. M. J. Med. Chem. 2010, 53, 855.
11. Navarrete-Vázquez, G.; Molina-Salinas, G. M.; Duarte-Fajardo, Z. V.; Vargas-
Villarreal, J.; Estrada-Soto, S.; González-Salazar, F.; Hernández-Núñez, E.; Said-
Fernández, S. Bioorg. Med. Chem. 2007, 15, 5502.
12. Khan, R. H.; Rastogi, R. C. J. Agric. Food Chem. 1990, 38, 1068.
13. Narayana, B.; Raj, K. K. V.; Ashalatha, B. V.; Kumari, N. S. Arch. Pharm. Chem. Life
Sci. 2005, 338, 373.
14. Schelenz, T.; Klunker, J.; Bernhardt, T.; Schafer, W.; Dost, J. Quant. Struct.-Act.
Relat. 2001, 20, 291.
15. Macaev, F.; Rusu, G.; Pogrebnoi, S.; Gudima, A.; Stingaci, E.; Vlad, L.; Shvets, N.;
Kandemirli, F.; Dimoglo, A.; Reynolds, R. Bioorg. Med. Chem. 2005, 13, 4842.
16. Klimesova, V.; Zahajska, L.; Waisser, K.; Kaustova, J.; Möllmann, U. Farmaco
2004, 59, 279.
Yield: 80%, mp: 79–81 °C. IR: 1315 (C@S), 1618 (C@N), 1647
(C@O), 3098 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
3.41 (s, 6H, 2Me), 5.00 (s, 2H, CH2), 7.25–8.01 (m, 7H, Ar), 8.60
(s, 1H, NH). Anal. Calcd for C19H16Cl2N4O2 (MW 467.39): C,
48.82; H, 3.45; N, 11.99. Found: C, 48.91; H, 3.48; N, 12.04.
6.3.63. Amino-3-(5-benzylsulfanyl-1,3,4-oxadiazol-2-yl)
anilinomethanethione (81)
Yield: 86%, mp: 177–179 °C. IR: 1463 (C@S), 1656 (C@N), 2727
(SCH2), 3345 (NH2) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
17. Mir, I.; Siddiqui, M. T. Tetrahedron 1970, 26, 5235.
4.57 (s, 2H, CH2), 6.95–8.39 (m, 11H, Ar, NH2), 9.93 (s, 1H, NH).
Anal. Calcd for C16H14N4OS2 (MW 342.44): C, 56.12; H, 4.12; N,
16.36. Found: C, 56.16; H, 4.21; N, 16.41.
18. Ulusoy, N.; Gürsoy, A.; Ötük, G. Farmaco 2001, 56, 947.
19. Kaplancıklı, S. A.; Turan-Zitouni, G.; Chevallet, P. J. Enzyme Inhib. Med. Chem.
2005, 20, 179.
20. Dimoglo, A.; Kovalishyn, V.; Shvets, N.; Ahsen, V. Mini-Rev. Med. Chem. 2005, 5,
879.
21. Dimoglo, A. S.; Vlad, P. F.; Shvets, N. M.; Coltsa, M. N. N. J. Chem. 2001, 25, 283.
22. Dimoglo, A. S.; Shvets, N. M.; Tetko, I. V.; Livingstone, D. J. Quant. Struct.-Act.
Relat. 2001, 20, 31.
23. Dimoglo, A.; Sim, E.; Shvets, N.; Ahsen, V. Mini-Rev. Med. Chem. 2003, 3, 293.
24. Sim, E.; Dimoglo, A.; Shvets, N.; Ahsen, V. Curr. Med. Chem. 2002, 9, 1537.
25. Oruç, E.; Rollas, S.; Kandemirli, F.; Shvets, N.; Dimoglo, A. J. Med. Chem. 2004,
47, 6760.
6.3.64. 2–5-[3-Methylamino(thioxo)methylaminophenyl]-1,3,4-
oxadiazol-2-ylsulfanyl-1-(2-naphthyl)-1-ethanone (82)
Yield: 80%, mp: 201–203 °C. IR: 1377 (C@S), 1615 (C@N), 1687
(C@O), 3190 (NH) cmꢀ1 1H NMR (d ppm, DMSO-d6, 400 MHz):
;
2.33 (d, 3H, J = 3.98 Hz, Me), 5.02 (s, 2H, SCH2), 7.68–8.02 (m,
11H, Ar), 8.15 (s, 1H, NHMe), 9.76 (s, 1H, NHAr). Anal. Calcd for
26. Koçyig˘it-Kaymakçıog˘lu, B.; Oruç, E.; Unsalan, S.; Kandemirli, F.; Shvets, N.;
Rollas, S.; Dimoglo, A. Eur. J. Med. Chem. 2006, 41, 1253.
C22H18N4O2S2 (MW 434.53): C, 60.81; H, 4.18; N, 12.89. Found: C,
27. Rusu, G. G.; Gutu, E. E.; Barba, N. A. Russ. J. Org. Chem. 1995, 31, 1721.
28. Collins, L.; Franzblau, S. G. Antimicrob. Agents Chemother. 1997, 41, 1004.
29. Wermuth, C. G. The Practice of Medicinal Chemistry; Academic Press: San Diego,
1996. pp 81–99.
60.93; H, 4.22; N, 12.94.
30. Cohen, N. C. Guidebook on Molecular Modelling in Drug Design; Academic Press:
San Diego, 1996. p 361.
7. In vitro evaluation of the antituberculosis activity
31. PDB ID:1CI0. Shi, W.; Ostrov, D.A.; Gerchman, S.E.; Graziano, V.; Kycia, H.;
Studier, B.; Almo, S.C.; Burley, S.K. New York Structural GenomiX Research
Consortium (NYSGXRC).
Primary screening was conducted at 6.25
tuberculosis H37Rv (ATCC 27294) in BACTEC 12B medium using a
lg/mL against M.

F. Macaev et al. / Bioorg. Med. Chem. 19 (2011) 6792–6807
6807
32. Biswal, B. K.; Cherney, M. M.; Wang, M.; Garen, C.; James, M. N. Acta Crystallogr.
2005, D61, 1492.
Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.;
Gonzalez, C.; Pople, J. A. GAUSSIAN-03, Revision A.1, Gaussian: Pittsburgh, PA,
2003.
33. Canaan, S.; Sulzenbacher, G.; Roig-Zamboni, V.; Scappuccini-Calvo, L.;
Frassinetti, F.; Maurin, D.; Cambillau, C.; Bourne, Y. FEBS Lett. 2005, 579, 215.
34. Molecular Operating Environment (MOE) software, release 2008.10.
35. Dewar, M. J. S.; Zoebisch, E. G.; Healy, E. F.; Stewart, J. J. P. J. Am. Chem. Soc.
1985, 107, 3902.
37. Dimoglo, A. S. Khim. Pharm. Zhur. 1985, 4, 438.
38. Dimoglo, A. S. In Book ‘Coordination and Organic Biologically Active Compounds’;
Kishinev, 1986. pp 7–11.
39. Bersuker, I. B.; Dimoglo, A. S. In Reviews in Computational Chemistry; Lipkowitz,
K. B., Boyd, D. B., Eds.; VCH: New-York, 1991. Chapter 10.
40. Shvets, N. M.; Dimoglo, A. S. Nahrung 1998, 42, 364.
41. Cramer, R. D.; DePriest, S. A.; Patterson, D. E.; Hecht, P. In 3D QSAR in Drug
Design: Theory Methods and Applications; Kubinyi, H., Ed.; ESCOM: Leiden: The
Netherlands, 1993; pp 443–486.
[36]. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.;
Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.; Kudin, K. N.; Burant, J. C.;
Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.; Mennucci, B.; Cossi, M.;
Scalmani, G.; Rega, N.; Petersson, G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.;
Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao,
O.; Nakai, H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Adamo,
C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.;
Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G.
A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A.
D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.;
Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.;
Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.;
Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
42. Tetko, I. V. J. Chem. Inf. Comput. Sci. 2002, 42, 717.
43. Tetko, I. V.; Livingstone, D. J.; Luik, A. I. J. Chem. Inf. Comput. Sci. 1995, 35, 826.
44. Tetko, I. V.; Kovalishyn, V. V.; Livingstone, D. J. J. Med. Chem. 2001, 44, 2411.
45. Tetko, I. V.; Villa, A. E. P.; Livingstone, D. J. J. Chem. Inf. Comput. Sci. 1996, 36,
794.
46. Kovalishyn, V. V.; Tetko, I. V.; Luik, A. I.; Kholodovych, V. V.; Villa, A. E. P.;
Livingstone, D. J. J. Chem. Inf. Comput. Sci. 1998, 38, 651.