Synthesis and antimicrobial studies of novel dichlorofluorophenyl containing aminotriazolothiadiazines

Article abstract of DOI:10.1016/j.ejmech.2007.03.024

Dichlorofluorophenyl containing aminotriazolothiadiazines (6) were synthesized by initial condensation of 2-chloro-N-(substituted phenyl) acetamides (4) with triazole (3) and further cyclization using POCl₃. The structures of newly synthesized compounds were confirmed by IR, NMR, mass and elemental analysis. All the compounds were screened for their antibacterial and antifungal activities. Compounds 5a, 5e, 5n, 5o, 6a, 6n, and 6o showed very good antibacterial and antifungal activities at 6.25 μg/ml concentrations.

Full text of DOI:10.1016/j.ejmech.2007.03.024

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European Journal of Medicinal Chemistry 43 (2008) 309e314
http://www.elsevier.com/locate/ejmech
Original article
Synthesis and antimicrobial studies of novel dichlorofluorophenyl
containing aminotriazolothiadiazines
a
b
Mari Sithambaram Karthikeyan a, , Bantwal Shivarama Holla , Nalilu Suchetha Kumari
*
a Department of Chemistry, Mangalore University, Mangalagangothri 574199, India
b Department of Biochemistry, K.S. Hegde Medical Academy, Deralakatte 574160, India
Received 2 December 2006; received in revised form 16 March 2007; accepted 19 March 2007
Available online 7 April 2007
Abstract
Dichlorofluorophenyl containing aminotriazolothiadiazines (6) were synthesized by initial condensation of 2-chloro-N-(substituted phenyl)
acetamides (4) with triazole (3) and further cyclization using POCl3. The structures of newly synthesized compounds were confirmed by IR,
NMR, mass and elemental analysis. All the compounds were screened for their antibacterial and antifungal activities. Compounds 5a, 5e,
5n, 5o, 6a, 6n, and 6o showed very good antibacterial and antifungal activities at 6.25 mg/ml concentrations.
Ó 2007 Elsevier Masson SAS. All rights reserved.
Keywords: 2,4-Dichloro-5-fluorophenyl triazole; Intramolecular cyclization; Aminotriazolothiadiazines; Antimicrobial activity
1. Introduction
antibacterial, antifungal and anticancer activities [13]. 6-
Aminotriazolothiadiazines were reported to possess good tu-
berculostatic activity [14]. The presence of an amino group
at 6th position of fused triazolothiadiazine system could con-
siderably enhance the biological potential of these
compounds.
1,2,4-Triazoles have been reported to possess antibacterial,
antifungal [1], antitubercular [2], anticancer [3], anticonvul-
sant [4], anti-inflammatory and analgesic properties [5]. The
arrangement of three basic nitrogen atoms in triazole is needed
for the antiviral activity [6]. 1,2,4-Triazole nucleus has been
incorporated into a wide variety of therapeutically interesting
drug candidates including H1/H2 histamine receptor blockers,
cholinesterase active agents, CNS stimulants, antianxiety and
sedative agents [7]. Thiadiazines were reported to possess
a wide spectrum of biological activities such as anti-inflamma-
tory [8], anti-HIV [9], antiplatelet, antithrombic [10] and anti-
fibrinolytic properties [11].
N-bridged heterocycles derived from 1,2,4-triazoles find
applications in the field of medicine, agriculture and industry.
Triazolothiadiazines represent an important class of N-
bridged heterocyclic compounds with a wide range of appli-
cations. These fused heterocycles are used as sedatives and
antisecretory agents [12], and also reported to exhibit
It was reported that the introduction of a halogen atom
augments the antimicrobial activity [15]. Numerous dichloro-
phenyl bearing organic compounds have various bioactivities,
which render them as valuable active ingredients of medi-
cines or plant protecting agents. Fluorinated compounds are
of growing importance with applications in medicine. Fluo-
rine substitution has profound effects on the properties of or-
ganic compounds. The very high electronegativity of fluorine
can modify the electronic distribution in the molecule, affect-
ing its absorption, distribution and metabolism. At present,
more than 200 fluorinated pharmaceuticals are available and
many other fluorinated pharmaceuticals are about to appear.
Fluorine containing molecules are used in medicine as anes-
thetics, antibiotics, anticancer, anti-inflammatory agents and
psychopharmaceuticals, and have many other applications
[16,17].
* Corresponding author. Tel.: þ91 824 2287262; fax: þ91 824 2287 367/
In light of such stimulating properties, it was contemplated to
synthesize some newer congeners of aminotriazolothiadiazines
424.
E-mail address: karthims02@rediffmail.com (M.S. Karthikeyan).
0223-5234/$ - see front matter Ó 2007 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2007.03.024

310
M.S. Karthikeyan et al. / European Journal of Medicinal Chemistry 43 (2008) 309e314
containing dichlorofluorophenyl moiety with a view to explore
their potency as better chemotherapeutic agents. Antibacterial
and antifungal activity results of newly synthesized aminotria-
zolothiadiazines were discussed in this paper.
5-fluorophenyl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine (6)
in good yields. The reaction sequence is outlined in Scheme 1.
3. Results and discussion
2. Chemistry
Formation of compounds 5 and aminotriazolothiadiazines
(6) was confirmed on the basis of IR, NMR, mass spectral
data and elemental analysis.
4-Amino-3-(2,4-dichloro-5-fluorophenyl)-5-mercapto-1,2,4-
triazole (3) was synthesized from 2,4-dichloro-5-fluoroacetophe-
none (1) as per the reported method [18]. Triazole (3) was treated
with 2-chloro-N-(substituted phenyl) acetamides [19] (4) in the
presence of potassium hydroxide in ethanol afforded N-(sub-
stituted phenyl)-2-{[4-amino-5-(2,4-dichloro-5-fluorophenyl)-
4H-1,2,4-triazol-3-yl]thio}acetamides (5). Compound 5 on
heating with phosphorus oxychloride underwent intramolecular
ring closure with the formation of 6-arylamino-3-(2,4-dichloro-
The IR spectrum of compound 5a showed a sharp absorption
band at 3338 cmꢀ1 indicating the presence of secondary amino
group. Asymmetric and symmetric stretching frequencies of
primary amino group appeared at 3269 and 3180 cmꢀ1, respec-
tively. The amide carbonyl stretching frequency was observed
at 1662 cmꢀ1. The other prominent absorption bands observed
in the IR spectrum are at 3028 (Ar-H), 2920 (CeH), 1600
(C]N), 1097 (CeF), 821 and 729 (CeCl) cmꢀ1
.
The 1H NMR spectrum of compound 5a showed a singlet at
d 2.17 due to the presence of CH3 protons. The SCH2 protons
resonated as a singlet at d 3.97. A broad singlet at d 4.78 in-
tegrating for two protons was attributable to NH2 protons.
The four protons of p-toludino moiety resonated as two dou-
blets at d 7.09 and 7.43 (J ¼ 8.2 Hz), respectively. A doublet
at d 7.36 (JHeF ortho ¼ 8.4 Hz) integrating for one proton was
attributable to the C6 proton of 2,4-dichloro-5-fluorophenyl
moiety. The C3 proton of 2,4-dichloro-5-fluorophenyl moiety
resonated as a doublet at d 7.61 (JHeF meta ¼ 6.5 Hz). The sig-
nal of the NH proton appeared as a singlet at d 9.69.
COCH3
COOH
F
F
Cl
Cl
Cl
Cl
1
2
F
N
N
In the IR spectrum of compound 6a, a sharp absorption
band at 3292 cmꢀ1 indicates the presence of secondary amino
group in the compound. The disappearance of the characteris-
tic primary amino and amide carbonyl stretching frequencies
of the starting materials indicates that the open chain com-
pound underwent intramolecular cyclization. The other prom-
inent absorption bands observed in the IR spectrum of 6a are
at 3070 (Ar-H), 2989 (CeH), 1591 (C]N), 1099 (CeF), 812
O
R
+
N
SH
Cl
Cl
NH
Cl
NH2
3
4
KOH
Ethanol
F
and 729 (CeCl) cmꢀ1
.
N
N
NH
The 1H NMR spectrum of compound 6a showed a singlet at
d 2.22 due to the presence of CH3 protons. The methylene protons
of the thiadiazine ring resonated as a singlet at d 3.98. The protons
of p-toludino moiety resonated as two doublets at d 7.03 and 7.4
(J ¼ 8.4 Hz) each integrating for two protons. A doublet at d 7.85
(JHeF ortho ¼ 9.6 Hz) integrating for one proton was attributable
to the C6 proton of 2,4-dichloro-5-fluorophenyl moiety. The C3
proton of 2,4-dichloro-5-fluorophenyl moiety resonated as a dou-
blet at d 8.08 (JHeF meta ¼ 6.8 Hz). The signal of the NH proton
appeared as a singlet at d 9.65.
S
N
R
Cl
O
Cl
NH2
5
POCl3
F
N
N
N
S
Cl
Further evidence for the formation of arylaminotriazolo-
thiadiazine (6a) was obtained by recording its mass spectrum.
The mass spectrum of the compound 6a showed molecular ion
peak and protonated molecular ion peak at m/z 407 and 408,
respectively, in conformity with the molecular formula C17H12
Cl2FN5S. The other prominent fragmentation peak was
observed at m/z 191 (10%) due to the formation of 2,4-di-
chloro-5-fluorobenzonitrile molecular cation. The character-
ization data of aminotriazolothiadiazines (6aeo) are given in
Table 1.
N
Cl
HN
R
6
R = 4-CH3, 4-Cl, 4-OCH3, 4-OC2H5, 4-F, 2,3-Cl2, 2,4-Cl2, 2,6-Cl2, 2,3-(CH3)2,
2,4-(CH3)2, 2,6-(CH3)2, 3,Cl-4F, 2,4,6-(CH3)3, 2,4,5-Cl3, 2-CF3
Scheme 1. Synthesis of aminotriazolothiadiazines (6).

M.S. Karthikeyan et al. / European Journal of Medicinal Chemistry 43 (2008) 309e314
311
Table 1
Characterization table of aminotriazolothiadiazines (6aeo)
Compound
R
Molecular formula
Mp (ꢂC)
Yield (%)
Analysis (%) found (calculated)
C
H
N
6a
6b
6c
6d
6e
6f
4-CH3
4-Cl
C17H12Cl2FN5S
C16H9Cl3FN5S
261e263
268e270
265e267
303e305
306e308
298e300
227e229
267e269
253e255
251e253
267e269
312e314
295e298
160e162
244e246
76
65
72
63
70
68
80
76
63
84
74
62
68
60
73
49.75 (50.00)
44.58 (44.81)
47.88 (48.11)
49.18 (49.32)
46.38 (46.60)
41.24 (41.47)
41.12 (41.47)
41.22 (41.47)
51.03 (51.18)
51.06 (51.18)
50.88 (51.18)
42.81 (43.00)
52.10 (52.29)
38.36 (38.59)
44.01 (44.16)
2.77 (2.94)
2.00 (2.10)
2.71 (2.83)
3.16 (3.20)
2.11 (2.18)
1.65 (1.73)
1.66 (1.73)
1.68 (1.73)
3.24 (3.32)
3.27 (3.32)
3.25 (3.32)
1.71 (1.79)
3.60 (3.67)
1.28 (1.40)
1.82 (1.95)
17.07 (17.16)
16.10 (16.34)
16.37 (16.51)
15.75 (15.98)
16.67 (16.99)
14.92 (15.12)
15.01 (15.12)
14.91 (15.12)
16.41 (16.59)
16.38 (16.59)
16.35 (16.59)
15.46 (15.68)
15.88 (16.05)
13.89 (14.07)
14.92 (15.15)
4-OCH3
4-OC2H5
4-F
C17H12Cl2FN5OS
C18H14Cl2FN5OS
C16H9Cl2F2N5S
2,3-Cl2
2,4-Cl2
2,6-Cl2
C16H8Cl4FN5S
C16H8Cl4FN5S
C16H8Cl4FN5S
C18H14Cl2FN5S
C18H14Cl2FN5S
C18H14Cl2FN5S
C16H8Cl3F2N5S
C19H16Cl2FN5S
C16H7Cl5FN5S
C17H9Cl2F4N5S
6g
6h
6i
2,3-(CH3)2
2,4-(CH3)2
2,6-(CH3)2
3-Cl-4-F
2,4,6-(CH3)3
2,4,5-Cl3
2-CF3
6j
6k
6l
6m
6n
6o
4. Pharmacological studies
4.2. Antifungal studies
4.1. Antibacterial studies
The newly prepared compounds were screened for their anti-
fungal activity against Candida albicans, Aspergillus flavus
(NICM no. 524), Aspergillus fumigatus (NICM no. 902),
Penicillium marneffei and Trichophyton mentagrophytes (recul-
tured) in DMSO by agar dilution method [22,23]. Sabouraud’s
agar media were prepared by dissolving peptone (1 g), D-glucose
(4 g)andagar(2 g)indistilledwater(100 ml)andadjustedthepH
to 5.7. Normal saline was used to make a suspension of spore of
fungalstrainfor lawning. A loopfulof particularfungalstrainwas
transferred to 3 ml saline to get a suspension of corresponding
species. Twenty milliliters of agar media was poured in to each
Petri dish. Excess of suspension was decanted and the plates
were dried by placing in an incubator at 37 ꢂC for 1 h. Using an
agar punch, wells were made and each well were labeled. A con-
trol was also prepared in triplicate and maintained at 37 ꢂC for 3e
4 days. The fungal activity of each compound was compared with
amphotericin B as standard drug. The inhibition zones were mea-
sured and compared with the controls. The nutrient broth, which
contained logarithmic serially twofold diluted amount of test
compound and controls inoculated with approximately
1.6 ꢁ 104e6 ꢁ 104 c.f.u/ml was used. The cultures were incu-
bated for 48 h at 35 ꢂC and the growth was monitored. The
lowest concentration (highest dilution) required to arrest the
growth of fungus was regarded as minimum inhibitory con-
centration (MIC). The fungal zone of inhibition and minimum
inhibitory concentration values are given in Table 3.
The newly prepared compounds were screened for their
antibacterial activity against Escherichia coli (ATCC-
25922), Staphylococcus aureus (ATCC-25923), Pseudomonas
aeruginosa (ATCC-27853), Streptococcus pyogenes and Kleb-
siella pneumoniae (recultured) bacterial strains by disc diffu-
sion method [20,21]. A standard inoculum (1e2 ꢁ 107 c.f.u/
ml 0.5 McFarland standards) was introduced onto the surface
of sterile agar plates and a sterile glass spreader was used for
even distribution of the inoculum. The discs measuring
6.25 mm in diameter were prepared from Whatman no. 1 fil-
ter paper and sterilized by dry heat at 140 ꢂC for an hour. The
sterile discs previously soaked in a known concentration of
the test compounds were placed in nutrient agar medium.
Solvent and growth controls were kept. The plates were in-
verted and incubated for 24 h at 37 ꢂC. Ciprofloxacin was
used as a standard drug. The inhibition zones were measured
and compared with the controls. Minimum inhibitory concen-
tration (MIC) was determined by broth dilution technique.
The nutrient broth, which contained logarithmic serially two-
fold diluted amount of test compound and controls was inoc-
ulated with approximately 5 ꢁ 105 c.f.u of actively dividing
bacteria cells. The cultures were incubated for 24 h at
37 ꢂC and the growth was monitored visually and spectropho-
tometrically. The lowest concentration (highest dilution) re-
quired to arrest the growth of bacteria was regarded as
minimum inhibitory concentration (MIC). The bacterial
zone of inhibition and minimum inhibitory concentration
values are given in Table 2.
The antifungal screening data showed only moderate activ-
ity. Among the screened compounds, compounds 5a, 5e, 5n,
5o, 6a, 6n and 6o emerged as active against all fungal strains
at 6.25 mg/ml concentrations.
The investigation of antibacterial screening data revealed
that all the tested compounds showed moderate to good bacte-
rial inhibition. The compounds 5a, 5c, 5e, 5l, 5n, 5o, 6a, 6b,
6n and 6o showed good inhibition towards all tested species
at 6.25 mg/ml concentrations.
5. Conclusion
Wehave synthesized aseries of dichlorofluorophenylbearing
uncyclized intermediates (5aeo) and aminotriazolothiadiazines

312
M.S. Karthikeyan et al. / European Journal of Medicinal Chemistry 43 (2008) 309e314
Table 2
Antibacterial activity data of 5 aeo and 6 aeo
Compound
Staphylococcus aureus
Escherichia coli
Pseudomonas aeruginosa
Klebsiella pneumoniae
Streptococcus pyogenes
5a
5b
25 (6.25)
17 (12.5)
24 (6.25)
e
29 (6.25)
14 (12.5)
30 (6.25)
e
31 (6.25)
18 (12.5)
32 (6.25)
e
20 (6.25)
12 (12.5)
21 (6.25)
e
22 (6.25)
10 (25)
23 (6.25)
e
5c
5d
5e
23 (6.25)
e
28 (6.25)
e
30 (6.25)
e
21 (6.25)
e
22 (6.25)
e
5f
5g
e
e
e
e
e
5h
5i
18 (6.25)
20 (6.25)
17 (6.25)
e
20 (12.5)
18 (12.5)
28 (6.25)
e
23 (12.5)
20 (12.5)
30 (6.25)
e
21 (6.25)
17 (12.5)
10 (25)
e
19 (6.25)
24 (6.25)
18 (6.25)
e
5j
5k
5l
5m
24 (6.25)
e
29 (6.25)
e
31 (6.25)
e
20 (6.25)
e
23 (6.25)
e
5n
5o
22 (6.25)
25 (6.25)
21 (6.25)
24 (6.25)
22 (6.25)
20 (6.25)
15 (12.5)
e
27 (6.25)
30 (6.25)
27 (6.25)
28 (6.25)
e
30 (6.25)
29 (6.25)
29 (6.25)
32 (6.25)
15 (25)
15 (25)
24 (12.5)
17 (12.5)
e
21 (6.25)
20 (6.25)
21 (6.25)
20 (6.25)
12 (12.5)
12 (12.5)
16 (12.5)
14 (12.5)
17 (12.5)
e
25 (6.25)
22 (6.25)
23 (6.25)
25 (6.25)
16 (12.5)
e
6a
6b
6c
6d
e
6e
22 (6.25)
20 (12.5)
22 (12.5)
10 (25)
13 (12.5)
23 (12.5)
18 (12.5)
22 (6.25)
15 (12.5)
28 (6.25)
29 (6.25)
30 (6.25)
22 (6.25)
e
6f
6g
e
e
e
6h
6i
e
15 (12.5)
10 (25)
11 (12.5)
21 (6.25)
18 (6.25)
15 (12.5)
23 (6.25)
23 (6.25)
25 (6.25)
25 (6.25)
e
23 (6.25)
e
12 (25)
18 (12.5)
15 (6.25)
20 (12.5)
16 (25)
32 (6.25)
30 (6.25)
33 (6.25)
19 (6.25)
14 (12.5)
12 (12.5)
11 (12.5)
8 (25)
6j
6k
6l
6m
23 (6.25)
24 (6.25)
22 (6.25)
25 (6.25)
6n
6o
20 (6.25)
21 (6.25)
22 (6.25)
Ciprofloxacin
The representation ‘e’ indicates that bacteria are resistant to the compounds >100 mg/ml. Diameter zone of inhibition is in millimeter. MIC values are given in
brackets. MIC (mg/ml) ¼ minimum inhibitory concentration, i.e., lowest concentration to completely inhibit bacterial growth.
(6aeo). Among the newly synthesized uncyclized intermedi-
ates, compounds containing 4-methyl, 4-fluoro, trichloro,
2-trifluoromethyl showed good antibacterial and antifungal
activities. In case of aminotriazolothiadiazines, compounds
with 4-methyl, trichloro and 2-trifluoromethyl showed good
antibacterial and antifungal activities.
6.2. Procedure for the preparation of 2-chloro-N-
(substituted phenyl) acetamides (4)
2-Chloro-N-(substituted phenyl) acetamides (4) were pre-
pared according to the literature method [19].
6.3. Procedure for the preparation of 2-{[4-amino-5-
(2,4-dichloro-5-fluorophenyl)-4H-1,2,4-triazol-3-yl]
thio}-N-phenyl acetamide (5)
6. Experimental protocols
Melting points were determined by open capillary method
and are uncorrected. The IR spectra (in KBr pellets) were re-
corded on a Shimadzu FT-IR 157 spectrophotometer. 1H NMR
spectra were recorded either on a Bruker 300 MHz or
400 MHz NMR spectrometer using TMS as an internal stan-
dard. The mass spectra were recorded on a MASPEC/FAB
mass spectrometer operating at 70 eV. The purity of the com-
pounds was checked by thin layer chromatography (TLC) on
silica gel plate using petroleum ether and ethyl acetate (2:1).
A solution of 2-chloro-N-(substituted phenyl) acetamides
(4) (0.01 mol) in ethanol (20 ml) was added to a solution of
triazole (2) (0.01 mol) in ethanol containing KOH
(0.01 mol). The reaction mixture was refluxed for 1 h, cooled
and then diluted with 50 ml of water. The precipitated solid
was filtered, washed with water, dried and recrystallised
from ethanol.
6.4. General procedure for the preparation of 6-
arylamino-3-(2,4-dichloro-5-fluorophenyl)-7H-
[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine (6)
6.1. Procedure for the preparation of 4-amino-3-(2,4-
dichloro-5-fluorophenyl)-5-mercapto-1,2,4-triazole (2)
A mixture of 2-{[4-amino-5-(2,4-dichloro-5-fluorophenyl)-
4H-1,2,4-triazol-3-yl]thio}-N-phenyl acetamide (5) (0.01 mol)
and 25 ml of phosphorous oxychloride was added and refluxed
4-Amino-3-(2,4-dichloro-5-fluorophenyl)-5-mercapto-1,2,4-
triazole (2) was synthesized according to the literature [18].

M.S. Karthikeyan et al. / European Journal of Medicinal Chemistry 43 (2008) 309e314
313
Table 3
Antifungal activity data of 5 aeo and 6 aeo
Compound
Candida albicans
Aspergillus flavus
Aspergillus fumigatus
Trichophyton mentagrophytes
Penicillium marneffei
5a
5b
18 (6.25)
12 (12.5)
e
22 (6.25)
10 (25)
e
20 (6.25)
15 (12.5)
e
18 (6.25)
8 (25)
23 (6.25)
17 (12.5)
e
5c
5d
e
e
e
e
e
e
5e
19 (6.25)
e
21 (6.25)
e
19 (6.25)
e
17 (6.25)
e
24 (6.25)
e
5f
5g
e
e
e
e
e
5h
5i
12 (12.5)
18 (6.25)
14 (12.5)
e
17 (6.25)
15 (12.5)
10 (25)
e
15 (12.5)
20 (6.25)
8 (25)
10 (25)
16 (6.25)
12 (6.25)
e
13 (12.5)
15 (12.5)
9 (25)
5j
5k
e
e
5l
5m
15 (12.5)
11 (12.5)
20 (6.25)
19 (6.25)
18 (6.25)
16 (6.25)
19 (6.25)
12 (12.5)
14 (12.5)
e
8 (25)
23 (6.25)
25 (6.25)
21 (6.25)
19 (6.25)
20 (6.25)
18 (6.25)
10 (25)
e
16 (12.5)
15 (12.5)
21 (6.25)
19 (6.25)
20 (6.25)
18 (6.25)
12 (12.5)
15 (12.5)
6 (25)
11 (12.5)
17 (6.25)
19 (6.25)
18 (6.25)
17 (6.25)
11 (12.5)
13 (12.5)
e
20 (6.25)
13 (12.5)
23 (6.25)
22 (6.25)
23 (6.25)
15 (12.5)
e
17 (12.5)
19 (6.25)
12 (12.5)
12 (12.5)
10 (25)
18 (6.25)
e
12 (12.5)
16 (12.5)
11 (12.5)
24 (6.25)
21 (6.25)
23 (6.25)
5n
5o
6a
6b
6c
6d
6e
18 (6.25)
8 (25)
6f
6g
e
11 (12.5)
19 (6.25)
10 (25)
16 (12.5)
9 (25)
15 (12.5)
18 (6.25)
10 (25)
8 (25)
8 (25)
e
11 (12.5)
12 (12.5)
e
6h
6i
e
6j
6k
15 (12.5)
24 (6.25)
e
12 (12.5)
19 (6.25)
10 (25)
14 (12.5)
18 (6.25)
17 (6.25)
19 (6.25)
15 (12.5)
e
10 (25)
e
6l
6m
13 (12.5)
20 (6.25)
18 (6.25)
20 (6.25)
e
e
6n
6o
23 (6.25)
21 (6.25)
25 (6.25)
19 (6.25)
21 (6.25)
22 (6.25)
Amphotericin B
The representation ‘e’ indicates that fungi are resistant to the compounds >100 mg/ml. Diameter zone of inhibition is in millimeter. MIC values are given in
brackets. MIC (mg/ml) ¼ minimum inhibitory concentration, i.e., lowest concentration to completely inhibit fungal growth.
for 2e3 h. Excess of POCl3 was removed by reduced pressure
and poured onto crushed ice and neutralized. The solid ob-
tained was filtered, washed, dried and recrystallised from suit-
able solvents.
6.4.3. Compound 6d
IR (KBr) g (cmꢀ1): 3295 (NH), 3081 (Ar-H), 2928 (CeH),
1599 (C]N), 1095 (CeF) and 829 (CeCl); 1H NMR (CDCl3)
d: 3.99 (s, 2H, SCH2), 7.07 (m, 2H, p-fluoroanilino protons),
7.53 (dd, 2H, p-fluoroanilino protons), 7.84 (d, 1H, dichloro-
fluorophenyl proton, JHeF ortho ¼ 9.6 Hz), 8.08 (d, 1H, dichlor-
ofluorophenyl proton, JHeF meta ¼ 6.8 Hz), 9.79 (s, 1H, NH
proton); FABMS (m/z, % abundance): 411 (Mþ, 10), 412
(Mþþ1, 100).
6.4.1. Compound 6b
IR (KBr) g (cmꢀ1): 3310 (NH), 3075 (Ar-H), 2976 (CeH),
1
1593 (C]N), 1089 (CeF), 821 and 735 (CeCl); H NMR
(CDCl3) d: 4.01 (s, 2H, SCH2), 7.28 (d, 2H, p-chloroanilino
protons, J ¼ 8.8 Hz), 7.54 (d, 2H, p-chloroanilino protons,
J ¼ 8.8 Hz), 7.84 (d, 1H, dichlorofluorophenyl proton,
JHeF ortho ¼ 9.2 Hz), 8.09 (d, 1H, dichlorofluorophenyl pro-
ton, JHeF meta ¼ 6.8 Hz), 9.89 (s, 1H, NH proton).
6.4.4. Compound 6e
IR (KBr) g (cmꢀ1): 3295 (NH), 3081 (Ar-H), 2928 (CeH),
1599 (C]N), 1095 (CeF) and 829 (CeCl); 1H NMR (CDCl3)
d: 3.99 (s, 2H, SCH2), 7.07 (m, 2H, p-fluoroanilino protons),
7.53 (dd, 2H, p-fluoroanilino protons), 7.84 (d, 1H, dichloro-
fluorophenyl proton, JHeF ortho ¼ 9.6 Hz), 8.08 (d, 1H, dichlor-
ofluorophenyl proton, JHeF meta ¼ 6.8 Hz), 9.79 (s, 1H, NH
proton); FABMS (m/z, % abundance): 411 (Mþ, 10), 412
(Mþþ1, 100).
6.4.2. Compound 6c
IR (KBr) g (cmꢀ1): 3294 (NH), 3094 (Ar-H), 1593 (C]N),
1097 (CeF), 816 and 735 (CeCl); 1H NMR (CDCl3) d: 3.70 (s,
3H, OCH3), 3.97 (s, 2H, SCH2), 6.80 (d, 2H, p-anisidino pro-
tons, J ¼ 8.8 Hz), 7.43 (d, 2H, p-anisidino protons, J ¼ 8.8 Hz),
7.84 (d, 1H, dichlorofluorophenyl proton, JHeF ortho ¼ 9.2 Hz),
8.08 (d, 1H, dichlorofluorophenyl proton, JHeF meta ¼ 6.8 Hz),
9.60 (s, 1H, NH protons); FABMS (m/z, % abundance): 423
(Mþ, 50), 408 (20), 191 (8).
6.4.5. Compound 6f
IR (KBr) g (cmꢀ1): 3315 (NH), 3099 (Ar-H), 2937 (CeH),
1
1595 (C]N), 1085 (CeF), 821 and 796 (CeCl); H NMR
(CDCl3) d: 4.11 (s, 2H, SCH2), 7.22 (t, 1H, dichloroanilino

314
M.S. Karthikeyan et al. / European Journal of Medicinal Chemistry 43 (2008) 309e314
proton), 7.43 (d, 1H, dichloroanilino proton, J ¼ 7 Hz), 7.67
(d, 1H, dichloroamidinophenyl proton, J ¼ 7.7 Hz), 7.74 (d,
6.4.12. Compound 6o
IR (KBr) g (cmꢀ1): 3312 (NH), 3099 (Ar-H), 1599 (C]N),
1085 (CeF) and 823 (CeCl); 1H NMR (CDCl3) d: 4.07 (s, 2H,
SCH2), 7.55 (m, 5H, o-trifluoromethylanilino and dichloro-
fluorophenyl protons), 7.96 (d, 1H, dichlorofluorophenyl pro-
ton, JHeF meta ¼ 6.8 Hz), 9.36 (s, 1H, NH proton).
1H, dichlorofluorophenyl proton, JHeF
¼ 9.6 Hz), 7.99
ortho
(d, 1H, dichlorofluorophenyl proton, JHeF
9.44 (s, 1H, NH proton).
¼ 6.8 Hz),
meta
6.4.6. Compound 6h
IR (KBr) g (cmꢀ1): 3299 (NH), 3097 (Ar-H), 1594 (C]N),
1083 (CeF) and 827 (CeCl); 1H NMR (CDCl3) d: 4.07 (s, 2H,
SCH2), 7.33 (t, 1H, dichloroanilino proton), 7.51 (d, 2H, di-
chloroanilino protons, J ¼ 8 Hz), 7.60 (d, 1H, dichlorofluoro-
Acknowledgements
The authors are grateful to Head, NMR Research Center,
IISc, Bangalore and CDRI, Lucknow, for providing 1H
NMR and mass spectral facilities. M.S.K. is grateful to
CSIR, New Delhi, for providing Senior Research Fellowship.
phenyl proton, JHeF
¼ 9.7 Hz), 7.92 (d, 1H,
meta
ortho
dichlorofluorophenyl proton, JHeF
1H, NH proton).
¼ 6.7 Hz), 9.70 (s,
References
6.4.7. Compound 6i
1H NMR (CDCl3) d: 2.05 (s, 3H, CH3), 2.17 (s, 3H, CH3),
4.06 (s, 2H, SCH2), 7.00 (m, 1H, dimethylanilino proton), 7.17
(m, 2H, dimethylanilino protons), 7.71 (d, 1H, dichlorofluoro-
phenyl proton, JHeF ortho ¼ 9.7 Hz), 7.97 (d, 1H, dichlorofluor-
ophenyl proton, JHeF meta ¼ 6.8 Hz), 9.11 (s, 1H, NH proton).
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6.4.8. Compound 6j
1H NMR (CDCl3) d: 2.19 (s, 3H, CH3), 2.22 (s, 3H, CH3),
4.01 (s, 2H, SCH2), 6.88 (d, 1H, dimethylanilino proton,
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ortho
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(s, 1H, NH proton).
¼ 6.7 Hz), 8.91
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6.4.9. Compound 6k
1H NMR (CDCl3) d: 2.16 (s, 6H, CH3), 4.05 (s, 2H, SCH2),
7.02 (s, 3H, dimethylanilino protons), 7.61 (d, 1H, dichloro-
fluorophenyl proton, JHeF ortho ¼ 9.3 Hz), 7.90 (d, 1H, dichlor-
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6.4.10. Compound 6l
IR (KBr) g (cmꢀ1): 3323 (NH), 3099 (Ar-H), 1605 (C]N),
1093 (CeF) and 818 (CeCl); 1H NMR (CDCl3) d: 4.03 (s, 2H,
SCH2), 7.24 (m, 1H, chlorofluoroanilino proton), 7.35 (t, 1H,
chlorofluoroanilino proton), 7.85 (d, 1H, dichlorofluorophenyl
proton, JHeF ortho ¼ 9.3 Hz), 7.97 (m, 1H, chlorofluoroamidi-
nophenyl proton), 8.11 (d, 1H, dichlorofluorophenyl proton,
JHeF meta ¼ 6.6 Hz), 10 (s, 1H, NH proton).
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6.4.11. Compound 6m
IR (KBr) g (cmꢀ1): 3309 (NH), 3089 (Ar-H), 1595 (C]N),
1
1091 (CeF), 817 and 738 (CeCl); H NMR (CDCl3) d: 2.07
(s, 3H, CH3), 2.11 (s, 3H, CH3), 2.15 (s, 3H, CH3), 3.97 (s, 2H,
SCH2), 6.81 (s, 2H, trimethylanilino protons), 7.62 (d, 1H, di-
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1H, NH proton).
¼ 6.3 Hz), 8.86 (s,
meta
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