Synthesis and preliminary evaluation of benzimidazole derivatives as antimicrobial agents

Article abstract of DOI:10.1016/S0223-5234(02)01342-9

A series of 2-alkylsulphanylbenzimidazoles was synthesised and the compounds were evaluated for their in vitro antimicrobial activity. The structures of the compounds were confirmed by ¹H-NMR and IR data, and their purity by elemental analysis. Antimycobacterial activities against Mycobacterium tuberculosis and non-tuberculous mycobacteria as well as antifungal activities against Candida albicans, Candida tropicalis, Candida krusei, Candida glabrata, Trichosporon beigelii, Trichophyton mentagrophytes and Aspergillus fumigatus were expressed as the corresponding MIC values. The substances exhibited appreciable antimycobacterial activity, in particular, against non-tuberculous mycobacteria. The activity of the most active compound in the set, 3,5-dinitro derivative 4t, exceeded that of the standard isoniazide against M. kansasii and M. avium. The antifungal activities of the compounds were relatively low. A weak antifungal effect was observed against the dermatophyte Trichophyton mentagrophytes. None of the compounds showed significant inhibitory activity against yeasts.

Full text of DOI:10.1016/S0223-5234(02)01342-9

Eur. J. Med. Chem. 37 (2002) 409–418
www.elsevier.com/locate/ejmech
Short communication
Synthesis and preliminary evaluation of benzimidazole derivatives
as antimicrobial agents
a,
Veˇra Klimesˇova´ *, Jan Kocˇ´ı a, Milan Pour a, Jirˇ´ı Stachel a, Karel Waisser a,
b
Jarmila Kaustova´
a Department of Inorganic and Organic Chemistry, Faculty of Pharmacy, Charles Uni6ersity, CZ-50005 Hradec Kralo6e, Czech Republic
b National Reference Laboratory for Mycobacterium kansasii, Regional Institute of Hygiene, CZ-72892 Ostra6a, Czech Republic
Received 31 July 2001; received in revised form 21 January 2002; accepted 23 January 2002
Dedicated to Professor Dr Roland Mayer on the occasion of his 75th birthday
Abstract
A series of 2-alkylsulphanylbenzimidazoles was synthesised and the compounds were evaluated for their in vitro antimicrobial
activity. The structures of the compounds were confirmed by 1H-NMR and IR data, and their purity by elemental analysis.
Antimycobacterial activities against Mycobacterium tuberculosis and non-tuberculous mycobacteria as well as antifungal activities
against Candida albicans, Candida tropicalis, Candida krusei, Candida glabrata, Trichosporon beigelii, Trichophyton mentagrophytes
and Aspergillus fumigatus were expressed as the corresponding MIC values. The substances exhibited appreciable antimycobacte-
rial activity, in particular, against non-tuberculous mycobacteria. The activity of the most active compound in the set, 3,5-dinitro
derivative 4t, exceeded that of the standard isoniazide against M. kansasii and M. a6ium. The antifungal activities of the
compounds were relatively low. A weak antifungal effect was observed against the dermatophyte Trichophyton mentagrophytes.
´
None of the compounds showed significant inhibitory activity against yeasts. © 2002 Editions scientifiques et me´dicales Elsevier
SAS. All rights reserved.
Keywords: Antimycobacterial activity; Antifungal activity; 2-Alkylsulphanyl derivatives; Benzimidazole
1. Introduction
second aspect contributing to tuberculosis incidence is
the rise in the occurrence of the multidrug resistant
strains of Mycobacterium tuberculosis. In addition, a
high number of infections with non-tuberculous my-
cobacteria, especially in immunocompromised patients
such as those infected with the human immunodefi-
ciency virus (HIV) [3], render the treatment even more
difficult. Of this group of Mycobacterium species, the
Mycobacterium a6ium complex (MAC), naturally resis-
tant towards a number of antimycobacterial drugs [4],
is considered to be the most dangerous strain. For the
treatment of tuberculosis, isoniazid (INH), rifampicin,
pyrazinamide, ethambutol, and streptomycin, generally
administered as a four-drug combination, are the most
widely used drugs. However, the protracted use of these
agents is one of the principal factors, which led to the
development of new resistant strains. Therefore, there is
an urgent need for the design, synthesis, and assay of
new potential drugs.
The deterioration of the epidemiological situation
caused by infectious diseases is becoming a world-wide
health problem. In the past few decades, tuberculosis is
regaining its place among those infections, which more
than often progress to a fatal end. Nearly one-third of
the world’s population is infected with Mycobacterium
tuberculosis, with approximately three million patients
deceasing every year [1].
The increasing incidence of tuberculosis in both de-
veloped and developing countries is one of the most
alarming aspects of the disease. For example, India,
South Africa, some of the states of the former Soviet
Union (Latvia, Lithuania, and Estonia), and USA [2]
belong to the areas most affected by the disease. The
* Correspondence and reprints:.
E-mail address: klimeso@faf.cuni.cz (V. Klimesˇova´).
´
0223-5234/02/$ - see front matter © 2002 Editions scientifiques et me´dicales Elsevier SAS. All rights reserved.
PII: S0223-5234(02)01342-9

410
V. Klimesˇo6a´ et al. / European Journal of Medicinal Chemistry 37 (2002) 409–418
In this paper, we describe the results of antimycobac-
In our previous work, we reported that the alkylsul-
terial activity evaluation of the derivatives of benzimi-
dazole-2-thiol, bearing an alkyl chain on the sulphur
atom in position 2. The alkyl group is either a linear or
branched C2–6,16 carbon chain, allyl, phenethyl and
benzyl fragment. The benzyl moiety is further modified
by groups with electron-accepting (NO2, CN, CF3) and
electron-donating (Cl, F, Br, OCH3) properties.
During our studies on new potential antimycobacte-
rial agents, we noted that some of them also showed
antifungal activity, and this fact prompted us to eva-
luate the newly prepared compounds for antifungal
properties as well.
phanyl group bound to an electron-deficient carbon
atom in various heterocycles is one of the pharma-
cophores of antimycobacterial activity [5]. A significant
antimycobacterial activity was observed in a large series
of alkylsulphanyl derivatives of pyridine [6–9], with
4-benzylsulphanyl derivatives of pyridine-2-carbonitrile/
2-carbothioamide being the most promising substances
[10]. As regards their activity profile, the compounds
exhibited antimycobacterial effect against both M. tu-
berculosis and nontuberculous mycobacteria. The va-
lues of MIC were within the range 4–125 mmol L−1
.
Compared to a standard, the derivatives matched the
activity of INH against M. tuberculosis (MIC 4
mmol L−1) and were superior to the drug against non-
tuberculous mycobacteria (MIC 500 mmol L−1 for
INH).
2. Chemistry
The synthetic pathways leading to 2-benzylsulphanyl
derivatives of benzimidazole are depicted in Fig. 1.
Benzimidazole-2-thiol (2), which serves as a convenient
starting material in the syntheses, was prepared accor-
ding to a literature procedure [23], by heating a mixture
of o-phenylenediamine (1), potassium hydroxide, and
carbon disulphide in 96% ethanol at reflux for 3 h. The
reaction afforded the starting compound 2 in 70% yield.
The alkylsulphanyl derivatives were prepared via
three procedures. Method A was used for the prepara-
tion of benzylsulphanyl derivatives 4. The treatment of
2 with various benzyl chlorides or bromides 3 was
carried out in N,N-dimethylformamide (DMF) in the
presence of sodium methanolate at room temperature.
The process required 2–8 h depending on the alkylating
The above results prompted us to continue our on-
going search for new substances containing heterocyclic
moieties other than pyridine. According to the litera-
ture, a large number of alkylsulphanyl derivatives of
1,2,4-triazole [11–14], tetrazole [15–17] benzothiazole
[18,19] and benzimidazole [20–22] were evaluated
against various strains of mycobacteria. Even though
the majority of these compounds displayed a rather
moderate activity, some of the derivatives of benzothia-
zole and benzimidazole exhibited appreciable antimy-
cobacterial effect. Because of the interesting chemical
properties of the benzimidazole ring, we decided to
synthesise
a set of alkylsulphanyl derivatives of
benzimidazole.
Fig. 1. Reagents: (a) CS2, KOH, ethanol; (b) Method A: Na, CH3OH, DMF; (c) Method B: Na, CH3CH2OH; (d) Method C: KOH,
(C4H9)4N+Br−, cyclohexane.

V. Klimesˇo6a´ et al. / European Journal of Medicinal Chemistry 37 (2002) 409–418
411
and the diagnostic bands of the carbothioamide func-
tion (CꢀS stretching vibration) in the derived deriva-
tives 7a and 7b were at 1437 and 1438 cm−1
,
respectively. The spectra of all alkylsulphanyl deriva-
tives showed the absorption signals of alkyl group
vibrations between 3000 and 2840 cm−1 (Table 5).
Fig. 2. Reagents: (a) H2S, TEA, pyridine.
agent and furnished products 4 in 40–90% yields. The
synthesis of alkylsulphanyl derivatives 6 was carried out
in ethanol at reflux (method B). Thiol 2 was converted
to the corresponding sodium salt by dissolving in an
ethanolic solution of sodium ethanolate, and the resul-
tant salt was subjected to a nucleophilic substitution
upon the addition of an alkyl halide 5. The yields
varied between 19 and 47%. In most reactions in boi-
ling ethanol, a second, more lipophilic product began to
form after several hours. These undesired byproducts
were identified as S,N-dialkylated compounds by IR
(vanishing of the NꢁH bond vibration) and NMR
spectroscopy. Thus, by terminating the reaction at an
appropriate stage, moderate to good yields of the S-
alkylated compounds could be obtained. Method C,
which was used for the preparation of some of com-
pounds 6 was based on the nucleophilic substitution
under phase-transfer conditions. The method involved
the alkylation of 2 with alkyl halides 5 in a two-phase
cyclohexane–aqueous potassium hydroxide system with
tetrabutylammonium bromide as a phase-transfer cata-
lyst. The reactions with short-chain alkyl halides (ethyl
bromide, propyl bromide) led to the formation of the
S-alkylated products with acceptable selectivity.
The benzylsulphanyl derivatives bearing the CN
group 4z, 4aa were further converted into the corre-
sponding carbothioamides 7a and 7b by the addition of
hydrogen sulphide in pyridine/triethylamine solution
(Fig. 2).
The structures of the compounds were confirmed by
1H-NMR and IR spectral data, and their purity by
elemental analysis. The singlet of the benzylic CH2S
group at 4.5–4.6 ppm was typical in the 1H-NMR
spectra of the benzylsulphanyl derivatives, while the
corresponding signal in the alkylsulphanyl derivatives
was shifted upfield and split into a triplet. The spectra
of all substances displayed multiplets in the aromatic
region indicating the presence of the benzimidazole
ring, and the NH resonance was apparent as a broad
singlet between 12.0 and 13.0 ppm. In the spectra of
substances with the carbothioamide group 7a and 7b,
NꢁH resonances were apparent between 9.4 and 9.9
ppm (Table 5).
3. Biology
In vitro antimycobacterial activity of the compounds
was evaluated against Mycocterium tuberculosis
CNCTC My 331/88, Mycobacterium kansasii CNCTC
My 235/80, Mycobacterium kansasii 6509/96 and My-
cobacterium a6ium CNCTC My 330/88 using the
micromethod for the determination of the minimum
inhibitory concentration. All strains were obtained
from the Czech National Collection of Type Cultures
(CNCTC), with the exception of M. kansasii 6509/96,
which was a clinical isolate.
In vitro antifungal activity was assessed on a panel of
one ATCC (Candida albicans ATCC 44859), and seven
clinical isolates of yeasts (Candida tropicalis 156, Can-
dida krusei E28, Candida glabrata 20/I) and filamentous
fungi (Trichosporon beigelii 1188, Trichophyton menta-
grophytes 445, Aspergillus fumigatus 231, Absidia
corymbifera 272) using the microdilution format of the
NCCLS M27-A guidelines.
4. Results and discussion
The results of the biological screening of the deriva-
tives are summarised in Tables 1 and 2. In several cases
(denoted \), the minimum inhibitory concentration
(MIC) could not be determined due to the limited
solubility of the compounds in the testing medium.
The values of antimycobacterial activity of the ben-
zylsulphanyl derivatives 4 and 7 are shown in Table 1.
For the sake of comparison, we also included the values
of MICs of 2 and the standard isoniazide (INH). The
results revealed that the compounds exhibited in vitro
activity against all tested mycobacterial strains. The
values of MICs are generally within the range 4–500
mmol L−1, most often between 8 and 125 mmol L−1
.
The compounds were less active than INH against M.
tuberculosis 331/88 and M. kansasii 6509/96. On the
other hand, in some cases, the compounds possessed a
better activity against M. kansasii 235/80 and M. a6ium
330/88 than INH. A significant activity was observed
for the compounds containing two nitro groups in
positions 3 and 5 (4t) and 2 and 4 (4u) in the benzyl
moiety. Compound 4t displayed the highest activity of
the set (MIC=4–8 mmol L−1). A promising effect was
shown by the thioamide derivative 7a, with MIC 8–62
mmol L−1. It is worthy to note that the activity of the
IR spectra of 2-alkylsulphanyl and 2-benzylsulphanyl
derivatives of benzimidazole were also in agreement
with the structures. The NꢁH absorption band between
3500 and 3220 cm−1 was particularly characteristic.
The compounds having the CN group (4z, 4aa) exhibi-
ted characteristic frequencies at 2227 and 2233 cm−1

412
V. Klimesˇo6a´ et al. / European Journal of Medicinal Chemistry 37 (2002) 409–418
Table 1
In vitro antimycobacterial activity of compounds 2, 4, 7 expressed as MIC (mmol L−1
)
Compounds
Strains
Myobacterium
tuberculosis My 331/88
Myobacterium kansasii My 235/80
Myobacterium kansasii My 6509/96 Myobacterium My
330/88
14 d
21 d
7 d
14 d
21 d
7 d
14 d
21 d
14 d
21 d
2
500
250
\32
\125
\125
62
125
\125
\32
\62
\125
\125
125
125
62
1000
\250
\125
\250
\125
125
250
16
\16
\16
125
32
250
\32
\32
\32
\125
62
500
125
32
32
32
32
32
32
32
62
62
32
32
32
16
8
125
\62
\62
\\62
\32
62
62
62
\62
\125
62
62
32
32
8
\62
250
62
62
32
250
\125
\62
\62
\62
62
500
125
\16
62
62
62
125
125
\62
\62
32
62
32
32
8
\16
250
16
16
32
1000
\125
\32
\62
\62
62
125
\125
\125
\125
62
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
4q
4r
\125
\62
\62
\125
125
125
32
32
62
125
62
62
\125
\125
\250
\125
\125
\125
250
\62
\125
250
125
\32
\62
32
32
62
125
\62
\62
\62
125
62
\125
\125
\125
\125
62
\125
\250
\62
\62
62
62
32
32
8
62
16
125
16
62
8
125
16
\62
250
62
\32
32
8
\32
250
62
\32
62
\32
125
32
\32
32
\62
\125
62
\32
62
\250
\125
125
\62
62
\32
125
32
32
16
4
\250
250
125
\62
32
\62
\62
62
4s
4t
4
4
4
8
8
8
8
8
4u
4v
4w
4x
4y
4z
4aa
7a
7b
INH
4
62
16
62
62
32
\62
16
62
8
125
32
62
\62
\62
\62
32
62
1
8
125
32
32
62
\62
62
8
62
\250
16
32
250
8
8
62
\32
62
62
\500
\62
8
125
4
16
16
32
125
\32
62
\62
\250
\62
8
62
16
32
32
\32
62
8
250
\62
62
\62
\500
\250
16
125
\32
62
\62
32
\62
32
125
\250
\250
\62
62
\125
62
\62
62
125
\250
\62
\62
\125
\500
\62
8
125
\250
125
\250
62
2
125
4
0.5
Table 2
In vitro antimycobacterial activity of compounds 6 expressed as MIC (mmol L−1
)
Compounds
Strains
Mycobacterium
tuberculosis My 331/88
Mycobacterium kansasii My 235/80 Mycobacterium kansasii My
6509/96
Myobacterium My
330/88
14 d
21 d
7 d
14 d
21 d
7 d
14 d
21 d
14 d
21 d
6a
6b
6c
6d
6e
6f
6g
6h
6i
\500
\125
\125
125
\500
\250
\250
125
500
125
\125
62
62
\62
\250
1000
500
250
\250
\500
250
\125
125
\500
\125
\250
125
500
125
125
62
\500
250
\125
62
\500
250
\250
125
500
125
125
62
\500
125
\125
\62
62
\125
\500
1000
1000
250
62
62
62
62
32
62
62
62
\62
\125
\1000
500
500
0.5
\62
\250
\1000
1000
500
\125
\500
\1000
1000
500
\250
\1000
\1000
1000
500
\250
\62
\250
1000
250
250
2
\62
\250
1000
500
500
4
\250
1000
1000
500
500
4
\62
\250
1000
500
250
\250
6j
INH
1
\250
\250

V. Klimesˇo6a´ et al. / European Journal of Medicinal Chemistry 37 (2002) 409–418
413
4-nitro derivative (4n) exceeded that of INH against
nontuberculous mycobacteria (MIC 8–16 mmol L−1),
while the activity against M. tuberculosis was lower
(MIC=62 mmol L−1).
4u, 4v) derivatives showed rather weak activities be-
tween 62 and 125 mmol L−1. The values of MICs
against all the remaining strains were higher than 125
mmol L−1. It is evident from Table 3 that the activity of
the standard ketoconazole (0.98–31.25 mmol L−1) was
not achieved.
The most active compound 4t was also subjected to
an antiproliferative effect assay against the K-562 and
L-929 cell lines. The values expressed as GI50 (growth
inhibition) are 11.4 and 9.7 mg mL−1. The cytotoxic
effect was evaluated on HeLa cells. The cytotoxic con-
centration expressed as CC50 (CC5) was 15.3 (3.5)
mg mL−1. According to the values of GI and CC,
compound 4t can be considered as moderately toxic.
The compounds with an aliphatic alkyl chain 6 are
summarised in Table 2. The values of MICs are in the
range 32–1000 mmol L−1 against all the tested my-
cobacterial strains. The results clearly show that the
most active compounds in the series are pentyl (6d) and
hexyl (6e) derivatives with activity between 62 and 125
mmol L−1. The activities of the two derivatives exceed
that of INH against M. kansasii 235/80 and M. a6ium
330/88. The lowest MICs were observed for 6h, 6i
(MIC=250–1000 mmol L−1).
The starting benzimidazole-2-thiol (2) is character-
ised by activity within the range 125–1000 mmol L−1
.
5. Experimental
Comparison of the data for compounds 2 to those of
the benzylsulphanyl derivatives indicates that the activ-
ity is linked to the substitution at position 2 of the
benzimidazole ring, as the substitution of the hydrogen
atom of the ꢁSH group at this position with an alkyl/
arylalkyl chain enhances the activity.
5.1. Chemistry
The melting points were determined in a Kofler block
and are uncorrected. Analytical samples were dried
over P4O10 at 82 or 61 °C and 2.4–2.6 kPa for 8–10 h.
Elemental analyses were performed on CHNS-O CE
instrument (FISONS EA 1110) and were within 9
0.4% of the calculated values. IR spectra were obtained
in a Nicolet Impact 400 spectrometer in KBr pellets
and CHCl3. NMR spectra were recorded in DMSO-d6
solutions at ambient temperature in a Varian Mercury-
Vx BB 300 spectrometer operating at 300 MHz. Che-
mical shifts were recorded as l values in ppm and were
indirectly referred to tetramethylsilane (TMS). Cou-
pling constants (J) are given in Hz. The reactions were
monitored and the purity of the products was checked
by TLC (Silufol UV 254 Kavalier, Votice, Czech repub-
lic and E. Merck TLC plates silica gel 60 F254, alu-
minium back) in acetone–light petroleum (for benzyl-
sulphanyl derivatives), ethylacetate–light petroleum
(for alkylsulphanyl derivatives). The plates were visu-
alised using UV light, iodine fumes and/or dipping in a
solution of Ce(SO4)2·4H2O, H3Mo12O40P·xH2O,
H2SO4, H2O and subsequent heating.
Preparative thin layer chromatography was carried
out in silica gel 60 F254 (0.015–0.040 mm, Merck).
Silica gel 60 (0.015–0.040 mm, Merck) was used for
column chromatography.
The following compounds had been described in the
literature: 4a, R=H [24–26]; 4b, R=4-Cl [26,27]; 4d,
R=2-Cl [28]; 4n, R=4-NO2 [26]; 4u, R=2,4-(NO2)2
[24]; 6a, R1=isopropyl [24]; 6b, R1=butyl [27,29,30];
6c, R1=isobutyl [30]; 6e, R1=hexyl [29]; 6h, R1=
ethyl [30,31]; 6i, R1=allyl [30–32]; 6j, R1=propyl
[30,31].
A more significant effect against the above men-
tioned strains was displayed by the benzylsulphanyl
derivatives 4 and 7. The activity was further improved
upon modification of the benzyl moiety by electron-
withdrawing groups. The most active derivative was the
3,5-dinitro compound 4t. As regards the substitution
with an aliphatic chain, the optimum chain length was
found to be 5–6 carbon atoms.
These findings about the relationship between the
structure of alkylsulphanyl derivatives and their an-
timycobacterial activity appear to be in agreement with
our previous results on pyridine derivatives [6–8,10].
The complete series of benzylsulphanyl derivatives (4
and 7) was also evaluated for antifungal activity. The
results are summarised in Table 3. We observed that
only three of the eight fungi strains were susceptible to
some of the derivatives tested. The most sensitive
strains were Trichophyton mentagrophytes 445, Asper-
gillus fumigatus 231 and Absidia corymbifera 272. As far
as the antifungal effect is concerned, some monosubsti-
tuted (4e, 4f, 4l, 4m, 4p) and disubstituted (4q, 4s, 4t,
Table 3
In vitro antifungal activity of some benzylsulphanyl derivatives 4
expressed as MIC (mmol L−1
)
MIC
Strains
TM (72 h)
AC (24 h)
AF (24 h)
62
4e, 4f, 4l, 4m, 4p, 4q, 4s, 4t, 4f
4e, 4s
4u
125
4v
4e
5.1.1. General procedure for compounds 4a–z, aa
Benzimidazol-2-thiol 2 (0.75 g, 5 mmol) in dry N,N-
dimethylformamide (8 mL) was added to a solution of
TM: Trichophyton mentagrophytes 445; AC: Absidia corymbifera 272;
AF: Aspergillus fumigatus 231. Standard Ketoconazole: TM (MIC
0.98), AC (MIC 31.25), AF (MIC 7.81).

414
V. Klimesˇo6a´ et al. / European Journal of Medicinal Chemistry 37 (2002) 409–418
Table 4
Yields and physicochemical properties of the compounds prepared
Compound
number
R
R1
Formula (molecular
weight)
Reaction time
(h)
Yield (%)
M.p. (°C) (crystallisation solvent)
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
4q
4r
H
4-Cl
3-Cl
2-Cl
4-F
3-F
2-F
4-Br
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
C
14H12N2S (240.3)
5
4
68
51
47
44
62
43
70
63
72
71
63
37
58
56
70
84
62
45
51
46
25
62
85
91
96
97
97
45
47
19
44
30
47
182–183 a (EtOH–H2O)
180–181 b (EtOH–H2O)
145–147 (EtOH–H2O)
160–164 c (MeOH–H2O)
142–146 (EtOH–H2O)
153–155 (MeOH–H2O)
171–173 (EtOH–H2O)
198–201 (EtOH)
C14H11ClN2S (274.8)
C14H11ClN2S (274.8)
C14H11ClN2S (274.8)
3.5
6
4.5
4.5
5.5
4
7
7.5
8
3
3.5
6
5
3
3
4
6
5
4
3
3
5
C14H11FN2S (258.3)
C14H11FN2S (258.3)
C14H11FN2S (258.3)
C
14H11BrN2S (319.2)
C14H11BrN2S (319.2)
15H14N2S (254.4)
C15H14N2S (254.4)
15H14N2OS (270.4)
3-Br
161–163 (EtOH)
4-CH3
3-CH3
4-OCH3
3-OCH3
4-NO2
3-NO2
2-NO2
2-F-6-Cl
3.4-Cl2
3.4-F2
3.5-(NO2)2
2.4-(NO2)2
2-F-6-NO2
4-CF3
3-CF3
3.5-(CF3)2
4-CN
3-CN
–
C
157–161 (EtOH–H2O)
125–131 (EtOH–H2O)
124–129 (EtOH–H2O)
116–123 (EtOH–H2O)
188–191 d (MeOH–H2O)
111–113 (MeOH–H2O)
133–135 (MeOH–H2O)
174–178 (EtOH–H2O)
173–174 (EtOH–H2O)
127–130 (EtOH–H2O)
155–158 (MeOH–H2O)
178–182 e (EtOH–H2O)
130–134 (MeOH–H2O)
200–204 (EtOH)
C
C15H14N2OS (270.4)
C14H11N3O2S (285.3)
C14H11N3O2S (285.3)
C14H11N3O2S (285.3)
C14H10FClN2S (292.8)
C14H10Cl2N2S (309.2)
C14H10F2N2S (276.3)
C14H10N4O4S (330.3)
C14H10N4O4S (330.3)
4s
4t
4u
4v
4w
4x
4y
4z
4aa
6a
6b
6c
6d
6e
6f
C
14H10FN3O2S (303.3)
C15H11F3N2S (308.3)
15H11F3N2S (308.3)
C16H10F6N2S (376.3)
C
148–149.5 (EtOH)
–
–
–
4
4
139–144 (EtOH–H2O)
178–184 (EtOH–H2O)
153–158 (EtOH–H2O)
181–184.5 f (EtOAc)
133.5–135 g (EtOAc)
165–167 h (EtOAc)
C
C
15H11N3S (265.3)
15H11N3S (265.3)
5.5
12.5
8
9.5
12
14.5
7
(CH3)2CH
C4H9
(CH3)2CH2CH C11H14N2S (206.3)
C5H11
C6H13
C10H12N2S (192.3)
C11H14N2S (206.3)
–
–
–
–
C12H16N2S (220.3)
C13H18N2S (234.4)
103–106 (EtOAc)
103–106 i (EtOAc)
–
C6H5ꢁCH2ꢁCH2 C15H14N2S (254.4)
151–152 (EtOAc)
6g
6h
6i
6j
7a
7b
–
–
–
–
C
C2H5
16H33
C23H38N2S (374.6)
C9H10N2S (178.3)
18
12
8.5
20
1.5
2.5
35
44
18
63
83
83
89–90 (EtOAc)
172–173.5 j (EtOAc)
133.5–135 k (EtOAc)
161–162 l (EtOAc)
182–186 (EtOH–H2O)
148–155 (EtOH–H2O)
CH2ꢀCHꢁCH2 C10H10N2S (190.3)
C3H7
–
–
C10H12N2S (192.3)
15H13N3S2 (299.4)
C15H13N3S2 (299.4)
4-CSNH2
3-CSNH2
C
a Refs. [24–26] give 184, 180–182, 187–188 °C.
b Refs. [26,27] give 185–186, 185 °C.
c Ref. [28] gives 141 °C.
d Ref. [26] gives 191–192 °C.
e Ref. [24] gives 181 °C.
f Ref. [24] gives 187 °C.
g Refs. [27,29,30] give 135, 134, 134–134.5 °C.
h Ref. [30] gives 167 °C.
i Ref. [29] gives 105 °C.
j Refs. [30,31] give 173, 173–174 °C.
k Refs. [30–32] give 139–140, 140–142 °C.
l Refs. [30,31] give 161, 161–162 °C.
sodium (0.12 g, 5 mmol) in dry methanol (2.5 mL).
After 10 min of stirring at room temperature, a benzyl
halide 3 (5 mmol) was added in 2–3 portions, and the
resultant suspension was stirred for 3–8 h. The reaction
mixture was then poured into an ice bath and left at
overnight. The solid was filtered off, washed with cold
water (2×30 mL) and air-dried. The crude products
were purified by preparative TLC using acetone–light
petroleum (1:2, 1:3, 1:4, 1:5 or 1:6), followed by crys-
tallisation from ethanol, ethanol–water or methanol–
water to afford the white or yellowish needles of the
pure compounds in 25–97% yields (Table 4).

V. Klimesˇo6a´ et al. / European Journal of Medicinal Chemistry 37 (2002) 409–418
415
Table 5
1H-NMR and IR spectroscopic data of the compounds prepared
Compound
number
1H-NMR l (ppm)
IR w, l (cm−1
)
4a
4b
4c
4d
4.57 (2H, s), 7.05–7.15 (2H, m), 7.20–7.35 (3H, m), 7.40–
7.55 (4H, m)
4.53 (2H, s), 7.05–7.15 (2H, m), 7.30–7.40 (2H, m AA%BB%), 3432 (NH), 3064–2054 (H-bridges)
7.40–7.50 (4H, m)
4.54 (2H, s), 7.05–7.15 (2H, m), 7.20–7.35 (2H, m), 7.35–
7.50 (3H, m), 7.51 (1H, bs)
3441 (NH), 3071–2344 (H-bridges)
3443 (NH), 3071–2631 (H-bridges)
4.65 (2H, s), 7.10–7.20 (2H, m), 7.20–7.65 (4H, m), 12.62
(1H, bs)
3451 (NH), 3070–2630 (H-bridges)
4e
4f
4.53 (2H, s), 7.05–7.15 (4H, m), 7.35–7.50 (4H, m)
4.55 (2H, s), 6.95–7.15 (3H, m), 7.20–7.35 (3H, m), 7.40–
7.50 (2H, m)
3440 (NH), 3070–2346 (H-bridges)
3432 (NH), 3060–2614 (H-bridges)
4g
4h
4.57 (2H, s), 7.05–7.25 (4H, m), 7.25–7.35 (1H, m), 7.40–
7.50 (2H, m), 7.51 (1H, td overlapped, J1=1.6 Hz, J2=
7.7 Hz)
4.53 (2H, s), 7.05–7.15 (2H, m), 7.30–7.60 (2H, m over-
lapped), 7.35–7.45 (2H, m AA%BB% overlapped), 7.45–7.55
(2H, m AA%BB% overlapped)
4.55 (2H, s), 7.05–7.15 (2H, m), 7.24 (1H, t, J=7.8 Hz),
7.30–7.55 (4H, m), 7.67 (1H, t, J=1.7 Hz)
2.24 (3H, s), 4.51 (2H, s), 7.05–7.15 (4H, m), 7.30–7.35
(2H, m AA%BB%), 7.40–7.50 (2H, m)
2.25 (3H, s), 4.52 (2H, s), 7.00–7.30 (6H, m), 7.30–7.45
(1H, m), 7.50–7.60 (1H, m)
3448 (NH), 3134–2638 (H-bridges)
3432 (NH), 3068–2611 (H-bridges)
3432 (NH), 3069–2629 (H-bridges)
4i
4j
4k
4l
3447 (NH), 3063–2630 (H-bridges), 2860 (CH3), 1445 (CH3),
1363 (CH3)
3445 (NH), 3042–2450 (H-bridges), 2858 (CH3), 1439 (CH3),
1364 (CH3)
.69 (3H, s), 4.50 (2H, s), 6.80–6.90 (2H, m AA%BB%), 7.05– 3443 (NH), 3066–2635 (H-bridges)
7.15 (2H, m), 7.30–7.40 (2H, m AA%BB% overlapped), 7.30–
7.40 (1H, m overlapped), 7.50–7.55 (1H, m)
4m
3.68 (3H, s), 4.52 (2H, s), 6.80 (1H, ddd, J1=1.0 Hz,
J2=2.5 Hz, J3=8.2 Hz), 6.95–7.05 (2H, m), 7.05–7.15
(2H, m), 7.21 (1H, t, J=7.7 Hz), 7.30–7.60 (2H, m)
4.68 (2H, s), 7.05–7.15 (2H, m), 7.35–7.55 (2H, m), 7.70–
7.80 (2H, m AA%BB%), 8.10–8.20 (2H, m AA%BB%)
4.69 (2H, s), 7.05–7.15 (2H, m), 7.35–7.55 (2H, m), 7.58
(1H, t, J=8.0 Hz), 7.91 (1H, dm, J=8.0 Hz), 8.07 (1H,
ddd, J1=0.9 Hz, J2=2.1 Hz, J3=8.0 Hz), 8.38 (1H, t,
J=2.1 Hz)
3438 (NH), 3063–2488 (H-bridges)
4n
4o
3440 (NH), 3077–2614 (H-bridges), 1518 (NO2), 1348 (NO2)
3443(NH), 3074–2448 (H-bridges), 1526 (NO2), 1350 (NO2)
4p
4.84 (2H, s), 7.05–7.15 (2H, m), 7.25–7.60 (2H, m over-
lapped), 7.51 (1H, td overlapped, J1=1.5 Hz, J2=7.7 Hz),
7.65 (1H, td, J1=1.5 Hz, J2=7.7 Hz), 7.78 (1H, dd, J1=
1.5 Hz, J2=7.7 Hz), 8.02 (1H, dd, J1=1.5 Hz, J2=7.7
Hz)
3420 (NH), 3072–2633 (H-bridges), 1535(NO2), 1351 (NO2);
4q
4r
4.68 (2H, d, J=1.7 Hz), 7.10–7.20 (2H, m), 7.20–7.30 (1H, 3443 (NH), 3064–2476 (H-bridges)
m), 7.35–7.50 (3H, m), 7.50–7.60 (1H, m)
4.54 (2H, s), 7.05–7.15 (2H, m), 7.35–7.50 (2H, m over-
lapped), 7.43 (1H, dd overlapped, J1=1.9 Hz, J2=8.2
Hz), 7.54 (1H, d, J=8.2 Hz), 7.73 (1H, d, J=1.9 Hz)
4.54 (2H, s), 7.05–7.15 (2H, m), 7.25–7.40 (2H, m), 7.40–
7.50 (2H, m), 7.53 (1H, ddd, J1=2.2 Hz, J2=8.0 Hz,
J3=11.8 Hz)
3443 (NH), 3065–2636 (H-bridges)
4s
3447 (NH), 3043–2502 (H-bridges)
4t
4.79 (2H, s), 7.05–7.15 (2H, m), 7.30–7.55 (2H, m), 8.66
(1H, t, J=2.2 Hz), 8.83 (2H, d, J=2.2 Hz)
4.92 (2H, s), 7.05–7.15 (2H, m), 7.35–7.50 (2H, m), 8.08
(1H, d, J=8.5 Hz), 8.47 (1H, dd, J1=2.5 Hz, J2=8.5
Hz), 8.69 (1H, d, J=2.5 Hz)
3424 (NH), 2969–2811 (H-bridges), 1541(NO2), 1345(NO2)
3427 (NH), 2955–2602 (H-bridges), 1531(NO2), 1345 (NO2)
4u
4v
4.82 (2H, d, J=1.4 Hz), 7.05–7.15 (2H, m), 7.35–7.50 (2H, 3423 (NH), 3096–2807 (H-bridges) 1530 (NO2), 1352 (NO2)
m), 7.50–7.70 (2H, m), 7.83 (1H, dt, J1=1.3 Hz, J2=7.7
Hz)
4w
4x
4.64 (2H, s), 7.05–7.15 (2H, m), 7.40–7.50 (2H, m), 7.66
(4H, bs)
4.64 (2H, s), 7.05–7.15 (2H, m), 7.40–7.50 (2H, m), 7.50–
7.65 (2H, m), 7.75 (1H, bd, J=7.4 Hz), 7.85 (1H, bs)
3432 (NH), 3074–2618 (H-bridges)
3446 (NH), 3079–2460 (H-bridges)

416
V. Klimesˇo6a´ et al. / European Journal of Medicinal Chemistry 37 (2002) 409–418
Table 5 (Continued)
Compound
number
1H-NMR l (ppm)
IR w, l (cm−1
)
4y
4.70 (2H, s), 7.05–7.15 (2H, m), 7.30–7.40 (1H, m), 7.45–
7.55 (1H, m), 7.95 (1H, bs), 8.21 (2H, bs)
3443 (NH), 2961–2618 (H-bridges)
4z
4.63 (2H, s), 7.05–7.15 (2H, m), 7.40–7.50 (2H, m), 7.60–
7.65 (2H, m AA%BB%), 7.75–7.80 (2H, m AA%BB%)
4.60 (2H, s), 7.05–7.15 (2H, m), 7.40–7.50 (2H, m over-
lapped), 7.50 (1H, t overlapped, J=7.7 Hz), 7.70 (1H, dt,
J1=1.5 Hz, J2=7.7 Hz), 7.79 (1H, dt, J1=1.5 Hz, J2=
7.7 Hz), 7.92 (1H, bt, J=1.5 Hz)
3428 (NH), 3088–2610 (H-bridges), 2227 (CN)
3432 (NH), 3065–2614 (H-bridges), 2233 (CN)
4aa
6a
6b
1.38 (6H, d, J=6.6 Hz), 3.85–4.05 (1H, m), 7.05–7.15 (2H, 3439 (NH), 2965, 1403, 1351
m), 7.35–7.50 (2H, m)
0.88 (3H, t, J=7.3 Hz), 1.30–1.50 (2H, m), 1.60–1.75 (2H, 3443 (NH), 2956, 1433, 1394
m), 3.26 (2H, t, J=7.1 Hz), 7.05–7.15 (2H, m), 7.35–7.50
(2H, m), 12.49 (1H, bs)
6c
6d
6e
0.99 (6H, d, J=6.9 Hz), 1.85–2.05 (1H, m), 3.18 (2H, d,
J=6.9 Hz), 7.05–7.15 (2H, m), 7.35–7.50 (2H, m), 12.5
(1H, bs)
0.85 (3H, t, J=7.2 Hz), 1.20–1.45 (4H, m), 1.60–1.75 (2H, 3447 (NH), 2957, 1440, 1401
m), 3.25 (2H, t, J=7.3 Hz), 7.05–7.15 (2H, m), 7.35–7.50
(2H, m), 12.5 (1H, bs)
0.84 (3H, t, J=7.1 Hz), 1.15–1.30 (4H, m), 1.30–1.50 (2H, 3447 (NH), 2957, 1440, 1401
m), 1.60–1.75 (2H, m), 3.25 (2H, t, J=7.3 Hz), 7.05–7.15
(2H, m), 7.35–7.45 (2H, m)
3432 (NH), 2957, 1441, 1398
6f
2.95–3.10 (2H, m), 3.45–3.60 (2H, m), 7.05–7.15 (2H, m),
7.20–7.25 (1H, m), 7.25–7.35 (4H, m), 7.40–7.50 (2H, m)
0.88 (3H, t, J=6.6 Hz), 1.10–1.35 (24H, m), 1.35–1.50
(2H, m), 1.65–1.85 (2H, m), 3.33 (2H, t, J=7.4 Hz), 7.15–
7.25 (2H, m), 7.40–7.60 (2H, m)
3432 (NH), 2959, 1439, 1402
6g
3444 (NH), 2919, 2850, 1442, 1402
6h
6i
1.35 (3H, t, J=7.4 Hz), 3.25 (2H, q, J=7.4 Hz), 7.05–
7.15 (2H, m), 7.35–7.50 (2H, m)
3.94 (2H, dm, J=6.9 Hz), 5.05–5.15 (1H, m), 5.25–5.35
(1H, m), 5.90–6.10 (1H, m), 7.00–7.20 (2H, m), 7.30–7.55
(2H, m)
3432 (NH), 2970, 1441, 1403
3447 (NH), 2965, 1441, 1406
6j
0.98 (3H, t, J=7.3 Hz), 1.65–1.80 (2H, m), 3.23 (2H, t,
J=7.1 Hz), 7.05–7.15 (2H, m), 7.50–7.30 (2H, m), 12.5
(1H, bs)
3432 (NH), 2967, 1433, 1397
7a
7b
4.58 (2H, s), 7.05–7.15 (2H, m), 7.30–7.60 (4H, m), 7.75–
7.85 (2H, m AA%BB%), 9.44 (1H, s), 9.83 (1H, s)
4.60 (2H, s), 7.05–7.15 (2H, m), 7.30–7.40 (1H, m over-
lapped), 7.33 (1H, t overlapped, J=7.8 Hz), 7.45–7.55
(1H, m), 7.57 (1H, bd, J=7.8 Hz), 7.70 (1H, bd, J=7.8
Hz), 8.01 (1H, bt, J=1.8 Hz), 9.50 (1H, s), 9.88 (1H, s)
3446 (NH), 2965–2641 (H-bridges), 1434 (C=S)
3424 (NH), 1438 (C=S), 3076–2796 (H-bridges)
5.1.2. General procedure for compounds 6a–g
pure compounds as white needles in 19–47% yield
(Table 4).
Benzimidazole-2-thiol (2) (0.6 g, 4 mmol) was added
to a stirred solution of sodium (0.1 g, 4 mmol) in 96%
ethanol (20 mL). After 10 min, an equivalent amount of
an alkyl halide 5 in 96% ethanol (10 mL,) was added
dropwise and the mixture was heated under reflux for
6–18 h. The reaction mixture was then cooled to room
temperature, and concentrated to dryness in vacuo. The
residue was redissolved in ethylacetate, and the solution
washed with brine (3×). The organic layer was dried
over Na2SO4 and the solvent removed. Purification of
the crude products by column chromatography (light
petroleum–ethylacetate, 85:15; light petroleum–ethy-
lacetate, 95:5; light petroleum–chloroform, 1:1), fol-
lowed by crystallisation from ethylacetate afforded
5.1.3. General procedure for compounds 6h–j
Alkyl halide 5 (7 mmol) was added to a solution of
benzimidazole-2-thiol (2) (1.0 g, 7 mmol) and tetrabuty-
lammonium bromide (0.1 g, 0.35 mmol) in cyclohexane
(20 mL). A 2 M aqueous solution of KOH (10.6 mL)
was further added and the resulting two-phase system
was vigorously stirred under reflux for 2–5 days de-
pending on the reactivity of halide 5. The reaction
mixture was cooled to room temperature, the phases
were separated, and the organic phase was washed with
H2O (3×) and dried over Na2SO4. The solvent was
removed in vacuo, and subsequent purification of the

V. Klimesˇo6a´ et al. / European Journal of Medicinal Chemistry 37 (2002) 409–418
417
crude residue by column chromatography (light
Acknowledgements
petroleum–ethylacetate, 85:15; light petroleum–ethy-
lacetate, 95:5; light petroleum–chloroform, 1:1), fol-
lowed by crystallisation from ethylacetate gave pure
products as white solids in 18–63% yields (Table 4).
This work was supported by the Grant Agency of
Charles University (grant No. 21/1999), the Grant
Agency of the Czech Republic (grant No. 203/02/
0082), and by the Ministry of Education of the Czech
Republic (Project No. MSM 111600001). We are in-
debted to Ms D. Karl´ıe`kova´ (Department of Pharma-
ceutical Chemistry and Drug Control, Faculty of
Pharmacy, Charles University) for performing elemen-
5.1.4. General procedure for compounds 7a and 7b
Dry hydrogen sulphide was passed through the so-
lution of a cyano compound (4z, 4aa) (0.5 g, 2 mmol)
dissolved in a mixture of dry pyridine (7 mL) and
triethylamine (0.7 mL). The reaction mixture was
maintained at room temperature for 3–4 h and then
heated at 45 °C for an additional hour. After cool-
ing, the mixture was poured onto crushed ice with
intensive stirring, the precipitated product was filtered
off, washed with cold water and air-dried. Preparative
TLC chromatography in acetone–light petroleum (1:1
or 1:2) and crystallisation from ethanol–water gave
the products as yellow needles in 83% yields (Table
4).
&
tal analyses and Ms J. Zizˇkova´ (Department of Inor-
ganic and Organic Chemistry, Faculty of Pharmacy,
Charles University) for recording the IR spectra. The
authors wish to thank to Dr V. Buchta (Department
of Biological and Medical Sciences, Faculty of Phar-
macy, Charles University) for performing the antifun-
gal tests and to Dr Ute Mo¨llmann for cytotoxicity
assays (Hans-Kno¨ll-Institut fuˆr Naturstoff-forschung,
Jena, Deutschland).
References
5.2. Microbiological methods
[1] A.M. Rouhi, Chem. Eng. News 17 (1999) 52–69.
5.2.1. Antimycobacterial acti6ity
The antimycobacterial activities of the compounds
[2] C.E. Barry, Biochem. Pharmacol. 59 (2000) 221–231.
[3] P. Sander, E.C. Bo¨ttger, Chemotherapy 45 (1999) 95–108.
[4] T.A. Vincent, Int. J. Antimicrob. Agents 16 (2000) 317–321.
&
were determined in the Sula semisynthetic medium
(SEVAC, Prague). The compounds were added to the
medium in dimethylsulphoxide solutions. The follow-
ing concentration were used: 1000, 500, 250, 125, 62,
32, 16, 8, and 4 mmol L−1. MICs were determined
after incubation at 37 °C for 7, 14, and 21 days.
MIC was the lowest concentration of a substance, at
which the inhibition of the growth of mycobacteria
occurred.
&
[5] K. Waisser, V. Klimesˇova´, Z. Odlerova´, Folia Pharm. Univ.
Carol. 18 (1995) 31–34.
[6] V. Klimesˇova´, M. Svoboda, K. Waisser, J. Kaustova´, V. Buchta,
K. Kra´lova´, Eur. J. Med. Chem. 34 (1999) 433–440.
&
[7] K. Waisser, V. Klimesˇova´, V. Buchta, Z. Odlerova´, Sci. Pharm.
65 (1997) 271–276.
[8] V. Klimesˇova´, M. Svoboda, K. Waisser, M. Macha´cˇek, V.
&
Buchta, Z. Odlerova´, Arch. Pharm. Pharm. Med. Chem. 329
(1996) 438–442.
[9] V. Klimesˇova´, M. Svoboda, K. Waisser, M. Pour, J. Kaustova´,
Farmaco 54 (1999) 666–672.
[10] V. Klimesˇova´, M. Svoboda, K. Waisser, M. Pour, J. Kaustova´,
Collect. Czech. Chem. Commun. 64 (1999) 417–434.
[11] B.V. Trzˇcinskaja, A.E. Aleksandrova, E.V. Apakina, T.I. Vino-
5.2.2. Antifungal acti6ity
The microdilution broth test was used for the as-
sessment of the antifungal effect. All substances were
dissolved in dimethylsulphoxide. Two-fold serial dilu-
tions of the compounds were used (1000–15
mmol L−1) provided that a given compound was solu-
ble in dimethylsulphoxide and stable in the culture
tissue medium (RPMI 1640, Sevac, Prague). The test
medium was buffered to pH 7.0 with 0.165 M mor-
pholine-4-propanesulphonic acid. Drug-free controls
were included. The yeast inocula were prepared from
24 to 72 h colonies grown on the Sabouraud agar at
37 °C. Conidia from 5 to 10-day-old colonies were
used to obtain suspensions of filamentous fungi. The
cell density in a sterile 0.85% saline was adjusted by
means of the Bu¨rker’s chamber. Antifungal activity of
the compounds in vitro was expressed as MIC, which
was determined after 24 h of static incubation at
35 °C. In the case of Trichophyton mentagrophytes,
the MICs were recorded after 72 and 120 h of incu-
bation.
&
gradova, R.A. Scˇegoleva, A.V. Afonin, Khim.-Farm. Zh. 25
(1991) 25–27.
[12] F. Saczewski, H. Foks, Acta Pol. Pharm. 45 (1988) 465–469.
[13] N. Gu¨lerman, S. Rollas, M. Kiraz, A.C. Ekinci, A. Vidin,
Farmaco 52 (1997) 691–695.
[14] T.E. Glotova, A.S. Nachmaninovicˇ, A.E. Aleksandrova, R.A.
&
Scˇegoleva, T.I. Vinogradova, Khim.-Farm. Zh. 23 (1989) 1338–
1340.
&
&
[15] J. Vanzˇura, A. Hraba´lek, Z. Odlerova´, K. Waisser, M. Celadn´ık,
&
Ces. a Slov. Farm. 34 (1985) 271–273.
&
[16] K. Waisser, J. Kunesˇ, A. Hraba´lek, M. Macha´cˇek, Z. Odlerova´,
Collect. Czech. Chem. Commun. 61 (1996) 791–798.
[17] J. Kunesˇ, A. Hraba´lek, M. Pour, M. Pilarˇ, K. Waisser, Z.
Odlerova´, Russ. J. Org. Chem. 34 (1998) 786–787.
[18] V. Sutoris, P. Folt´ınova´, G. Blo¨ckinger, Chem. Zvesti. 31 (1977)
92–97.
&
&
[19] E. Sido´ova´, Z. Odlerova´, F. Volna´, G. Blo¨ckinger, Chem. Zvesti.
33 (1979) 830–836.
[20] V.L. Khairnar, S.R. Lokhande, M.R. Patel, B.G. Khadse, Bull.
Haffkine Inst. 8 (1980) 53–56.
[21] A.V. Pande, P.A. Kirke, B.G. Khadse, Bull. Haffkine Inst. 11
(1983) 51–55.

418
V. Klimesˇo6a´ et al. / European Journal of Medicinal Chemistry 37 (2002) 409–418
[27] W. Knobloch, G. Winklemann, K. Rintelen, Arch. Pharm. 291
(1958) 113–117 (Chem.Abstr. 52 (1958) 17242e).
[28] S.S. Tiwari, G.L. Trivedi, Indian J. Appl.Chem. 34 (1971) 80–
82.
[22] B.V. Trzˇcinskaja, A.E. Aleksandrova, N.D. Abramova, L.V.
&
Andrijankova, T.I. Vinogradova, R.A. Scˇegoleva, Khim.-Farm.
Zh. 26 (1992) 57–60.
[23] J.E. Van Allan, B.D. Deacon, Org. Synth. Coll. 4 (1963) 569–
570.
[24] C. Angelini, Ann. Chim. (Rome) 45 (1955) 162–165 (Chem.
Abstr. 49 (1955) 11627b).
[25] N.P. Bednyagina, I.Y. Postovskii, Nauch. Doklady Vysshen
Shkoly Khim. i Khim. Tekhnol. 2 (1959) 333–337 (Chem. Abstr.
54 (1960) 510a).
[26] A.M. Cummings, Johnston, H.A. Stevenson, Nauch. Doklady
Vysshen Shkoly Khim. i Khim. Tekhnol. 2 (1958) 143–147
(Chem. Abstr. 52:11773d).
[29] D.B. Saxena, R.K. Khajuria, O.P. Suri, J. Heterocycl. Chem. 19
(1982) 681–683 (Chem. Abstr. 97 (1982) 198144u).
[30] S. Nakajima, I. Tanaka, T. Seki, T. Anmo, Yakugaku Zasshi 78
(1958) 1378–1382 (Chem. Abstr. 53 (1959) 8124e).
[31] N.K. Rozˇkova´, L.V. Zavjalovova´, S. Achmedovova´, K.V. Anan-
jevova´, V.V. Nagrebeckaja, Z.F. Sajfulinova´, A.A. Umarov,
Fungitsidy (1980) 94–103 (Chem. Abstr. 94 (1981) 78267c).
[32] O.P. Suri, R.K. Khajuria, D.B. Saxena, N.S. Rawat, C.K. Atal,
J. Heterocycl. Chem. 20 (1983) 813–814 (Chem. Abstr. 99 (1983)
139844r).