Synthesis, characterization of 4,6-disubstituted aminopyrimidines and their sulphonamide derivatives as anti-Amoebic agents

Article abstract of DOI:10.1007/s00044-013-0877-9

The present study describes the synthesis and anti-Amoebic activity of 4,6-disubstituted aminopyrimidines (1b-10b) and their sulphonamide derivatives (1-20). All the desired compounds were characterized by spectral data and their purity was confirmed by e

Full text of DOI:10.1007/s00044-013-0877-9

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-013-0877-9
ORIGINAL RESEARCH
Synthesis, characterization of 4,6-disubstituted aminopyrimidines
and their sulphonamide derivatives as anti-amoebic agents
•
Shadab Miyan Siddiqui Amir Azam
Received: 13 May 2013 / Accepted: 7 November 2013
Ó Springer Science+Business Media New York 2013
Abstract The present study describes the synthesis and
anti-amoebic activity of 4,6-disubstituted aminopyrimi-
dines (1b–10b) and their sulphonamide derivatives (1–20).
All the desired compounds were characterized by spectral
data and their purity was confirmed by elemental analysis.
The aim of the study was to explore the effect of the target
compounds on in vitro growth of HM1:IMSS strain of
Entamoeba histolytica. In vitro anti-amoebic activity was
performed by microdilution method and the results were
compared with standard drug metronidazole. The results
revealed that sulphonamide derivatives (1–20) showed
better activity than 4,6-disubstituted aminopyrimidines
(1b–10b). 5 pyrimidine and 12 sulphonamide derivatives
were better inhibitors of the growth of E. histolytica than
the reference drug metronidazole (IC50 = 1.80 lM). The
promising in vitro anti-amoebic activity of the compounds
make them promising molecules for further lead optimi-
zation in the development of novel anti-amoebic agents,
therefore, it is hoped that these preliminary results could
help in designing better molecules with an enhanced anti-
amoebic activity.
infected patients in an area endemic for amoebic infection
(Hung et al., 1999). Amoebiasis poses a serious health
problem, with 100,000 deaths per year, making it the
second leading cause of death due to parasitic disease
(Ralston and Petri, 2011). However, anti-amoebic chemo-
therapy relies on 5-nitroimidazoles, but long-term use of
these medications produce a number of serious side effects
in patients (Ordaz-Pichardo et al., 2005). Metronidazole
(MNZ) is the medication of choice for invasive amoebiasis;
however, it is not known whether its dose or duration
require modification in HIV infection when treating inva-
sive amoebiasis (Ohnishi and Uchivama-Nakamura, 2012).
Furthermore, it is mutagenic and has been associated with
promiscuous side effects (Ordaz-Pichardo et al., 2005).
Therefore, the search for new effective anti-amoebic
compounds is required.
Among various nitrogen containing heterocycles,
pyrimidine is promising structural moiety for drug
designing. Pyrimidine and their derivatives have been
found to be endowed with anti-amoebic activities (Parveen
et al., 2010, 2011; Siddiqui et al., 2013a). The 2-amino-
pyrimidine, which is a common structural subunit in a
number of biologically active natural as well synthetic
compounds, has been widely used as a drug like scaffold
(Lagoja, 2005). Aminopyrimidine derivatives substituted at
N-position are of immense importance because they exhibit
multifaceted biological and pharmacological activities.
Considering this perspective, we decided to design com-
pounds having aminopyrimidine ring (1b–10b) as well as
the compounds derived from this bioactive core (1–20)
(Fig. 1). It was expected that the compounds derived from
pyrimidine core incorporating sulphonamide moiety might
exhibit better anti-amoebic activity than the compounds
having only pyrimidine moiety. The hypothesis behind it is
that our recent studies indicate that like pyrimidine,
Keywords Pyrimidine Á Sulphonamide Á
Anti-amoebic activity Á HM1:IMSS Á E. histolytica
Introduction
Amoebiasis, caused by parasitic protozoan Entamoeba
histolytica, is an emerging parasitic disease in HIV-
S. M. Siddiqui Á A. Azam (&)
Department of Chemistry, Jamia Millia Islamia, Jamia Nagar,
New Delhi 110025, India
e-mail: amir_sumbul@yahoo.co.in
123

Med Chem Res
Fig. 1 4,6-Disubstituted
aminopyrimidines (1b–10b) and
their sulphonamide derivatives
(1–20)
R1
R2
N
S
N
NH
R1
R2
O
N
N
O
R3
NH2
(1b-10b)
(1-20)
Scheme 1 General method for
the synthesis of sulphonamide
derivatives of 4,6-disubstituted
aminopyrimidines (1–20).
Reagent and conditions:
a Guanidine hydrochloride,
sodium isopropoxide,
isopropanol and reflux; b 10 %
NaOH, benzenesulphonyl or
toluene-p-sulphonyl chloride
and warm
O
(a)
R1
R2
R2
R1
(1a-10b)
N
N
NH2
(1b-10b)
(b)
R1
R2
N
S
N
O
NH
O
R3
(1-20)
sulphonamide is crucial structural feature for the display of
anti-amoebic activity (Salahuddin et al., 2013; Siddiqui
et al., 2013a), further the introduction of sulphonamide
group increases pharmacological potency and/or the
absorption, distribution, metabolism and excretion (ADME)
attributes of the lead chemical matter (Dai et al., 2011).
Therefore, the combination of these two moieties is expected
to exhibit synergistic effects to display anti-amoebic activ-
ity. In view of this, we herein report the synthesis and anti-
amoebic activity of 4,6-disubstituted aminopyrimidines
(1b–10b) and their sulphonamide derivatives (1–20).
aryl aldehydes by a reported method (Li et al., 1995). 1,3-
diaryl-2-propen-1-ones (1a–10a) were further cyclized
with guanidine hydrochloride in the presence of sodium
isopropoxide (synthesized in situ by adding sodium metal
in isopropanol) to afford 4,6-disubstituted aminopyrimi-
dines (1b–10b) (Sunduru et al., 2006). Finally, the con-
densation of 4,6-disubstituted aminopyrimidines (1b–10b)
with benzene sulphonyl chloride or toluene-p-sulphonyl
chloride furnished sulphonamide derivatives of 4,6-disub-
stituted aminopyrimidines (1–20) (Furniss et al., 1989).
The structures of these compounds were elucidated by
spectral studies and their purity was confirmed by ele-
mental analyses.
Results and discussion
Anti-amoebic activity
Chemistry
In order to explore the potential of 4,6-disubstituted am-
inopyrimidines (1b–10b) and their sulphonamide deriva-
tives (1–20) as possible scaffold for E. histolytica
inhibitors, all these compounds were evaluated against
HM1:IMSS strain of E. histolytica. All the experiments
were carried out in triplicate at each concentration level
and repeated thrice. The anti-amoebic effect was compared
The synthetic pathway leading to the target compounds is
depicted in Scheme 1. 4,6-disubstituted aminopyrimidines
(1b–10b) were obtained through synthesis of 1,3-diaryl-2-
propen-1-ones (1a–10a). The synthesis of these compounds
(1a–10a) was based on Claisen–Schmidt condensation of
acetophenone and 4-chloro-acetophenone with different
123

Med Chem Res
Table 1 In vitro anti-amoebic activity of 4,6-disubstituted amino-
pyrimidines (1b–10b) against HM1:IMSS strain of E. histolytica
Table 2 In vitro anti-amoebic activity of sulphonamide derivatives
of 4,6-disubstituted aminopyrimidines (1–20) against HM1:IMSS
strain of E. histolytica
R1
R2
R1
R2
N
N
N
S
N
NH2
O
NH
(1b–10b)
O
R3
(1–20)
Compounds
R1
R2
IC50 (lM)a
S.D.
1b
H
H
6.15
2.50
1.72
1.54
4.47
7.21
1.63
1.66
5.74
1.59
1.80
0.06
0.01
0.05
0.05
0.03
0.06
0.05
0.03
0.06
0.03
0.05
Compounds
R1
R2
R3
IC50 (lM)a
S.D.
2b
4-Cl
H
1
H
H
H
H
H
H
2.34
1.95
0.70
1.35
0.44
0.90
0.73
1.44
3.04
2.68
5.32
2.70
1.57
1.02
1.60
1.42
3.62
4.01
1.10
0.04
1.80
0.04
0.05
0.01
0.06
0.05
0.01
0.01
0.04
0.02
0.04
0.01
0.06
0.06
0.07
0.01
0.04
0.04
0.06
0.05
0.01
0.05
3b
H
2-Cl
2-Cl
3-Cl
3-Cl
4-Cl
4-Cl
3,4-Cl
3,4-Cl
2
H
4-CH3
H
4b
4-Cl
H
3
4-Cl
4-Cl
H
5b
4
4-CH3
H
6b
4-Cl
H
5
2-Cl
7b
6
H
2-Cl
4-CH3
H
8b
4-Cl
H
7
4-Cl
4-Cl
H
2-Cl
9b
8
2-Cl
4-CH3
H
10b
MNZ
4-Cl
9
3-Cl
10
11
12
13
14
15
16
17
18
19
20
MNZ
H
3-Cl
4-CH3
H
S.D. standard deviation
a
The values obtained in at least three separate assays done in
triplicate
4-Cl
4-Cl
H
3-Cl
3-Cl
4-CH3
H
4-Cl
H
4-Cl
4-CH3
H
with the most widely used medication MNZ. MNZ had a
50 % inhibitory concentration (IC50) 1.80 lM in our
present experiments which has been found similar to our
previous studies (Siddiqui et al., 2012, 2013b). The results
are given in Table 1 and 2. In terms of structure activity
relationship (SAR), it was concluded that sulphonamide
derivatives (1–20) showed better activity than 4,6-disub-
stituted aminopyrimidines (1b–10b). Out of 10 4,6-disub-
stituted aminopyrimidines (1b–10b), 5 compounds: 3b
4-Cl
4-Cl
H
4-Cl
4-Cl
4-CH3
H
3,4-Cl
3,4-Cl
3,4-Cl
3,4-Cl
H
4-CH3
H
4-Cl
4-Cl
4-CH3
S.D. standard deviation
a
The values obtained in at least three separate assays done in
triplicate
(IC50 = 1.72 lM), 4b (IC50 = 1.54 lM), 7b (IC50
=
1.63 lM), 8b (IC50 = 1.66 lM) and 10b (IC50 = 1.59 lM)
were found to exhibit better activity than MNZ
(IC50 = 1.80 lM). On the other hand, out of 20 sulphona-
mides derivatives (1–20), 12 compounds: 3 (IC50
0.70 lM), 4 (IC50 = 1.35 lM), 5 (IC50 = 0.44 lM), 6
(IC50 = 0.90 lM), (IC50 = 0.73 lM), (IC50
1.44 lM), 13 (IC50 = 1.57 lM), 14 (IC50 = 1.02 lM), 15
(IC50 = 1.60 lM), 16 (IC50 = 1.42 lM), 19 (IC50
aminopyrimidines block the Entamoeba protein functioning
by reaction with the sulphahydryl group present in the par-
asite in high amount. The IC50 values of sulphonamide
derivatives support our estimation. Although, the mechanism
of the biological activity needs further investigations, which
are in progress.
=
7
8
=
=
1.10 lM) and 20 (IC50 = 0.04 lM) had IC50 value less than
MNZ (IC50 = 1.80 lM), and therefore were considered to
be better inhibitors of in vitro growth of HM1:IMSS strain
of E. histolytica. It has been reported that sulphona-
mides block the metabolic pathway of malaria parasite by
competing with p-aminobenzoic acid. Likewise, we might
expect that sulphonamide derivatives of 4,6-disubstituted
Experimental protocol
Melting points (mp) were recorded by Capillary method
and are uncorrected. Elemental analysis was carried out on
Heraeus Vario EL III analyzer by Central Drug Research
123

Med Chem Res
Instituted, Lucknow, India and the results were within 0.3
of the theoretical values. IR spectra were recorded on
Perkin Elmer model 1620 FT-IR spectrophotometer as KBr
14.90 %; IR: mmax(cm-1): 3389 (NH2), 1519, 1461 (C=N);
1H NMR (CDCl3): (d, ppm): 5.16 (s, 2H, NH2), 6.98 (s, 1H,
Ar–H), 7.80–7.84 (m, 5H, Ar–H), 7.19 (d, 2H, J = 7.1,
Ar–H), 7.23 (d, 2H, J = 7.1, Ar–H); 13C NMR (CDCl3):
(d, ppm): 163.6 (C=N pyrimidine), 163.3 (C=C pyrimi-
dine), 162.1 (N=C–N pyrimidine), 135.1 (Ph), 133.6, (Ph)
131.2 (Ph), 129.3 (Ph), 129.3 (Ph), 128.8 (Ph), 126.5 (Ph),
86.4 (C–H pyrimidine); FAB-MS: m/z (M??1) 282.86
calc. 281.74.
1
discs. The H NMR and 13C NMR spectra were recorded
on Bruker Spectrospin DPX 300 MHz and Bruker Spec-
trospin DPX 75 MHz spectrometer, respectively, using
DMSO-d6 as a solvent and trimethylsilane (TMS) as an
internal standard. During interpretation of 1H and 13C
NMR a few abbreviations has been used which are s
(singlet), d (doublet), m (multiplet), Ar (aromatic) and Ph
(phenyl). The FAB-MS spectra of all the compounds were
recorded on JEOL SX 102/DA-6000 mass spectrometer
using Argon/Xenon 6 kV, 10 mA as the FAB gas, and m-
nitro benzyl alcohol (NBA) was used as the matrix.
4-(2-Chlorophenyl)-6-phenylpyrimidin-2-amine (3b)
Yield: 78 %; m.p. 61 °C. Anal. Calc. for (C16H12ClN3): C
68.2, H 4.29, N 14.9 %; Found: C 68.1, H 4.39, N 14.7 %;
1
IR: mmax(cm-1): 3397(NH2), 1549, 1446 (C=N); H NMR
General procedure for preparation of 1,3-diaryl-2-
(CDCl3): (d, ppm): 5.21 (s, 2H, NH2), 7.46 (s, 1H, Ar–H),
7.90–7.95 (m, 5H, Ar–H), 7.38–7.40 (m, 4H, Ar–H); 13C
NMR (CDCl3): (d, ppm): 162.2 (C=N pyrimidine), 161.9
(C=C pyrimidine), 161.3 (N=C–N pyrimidine), 132.3 (Ph),
132.3 (Ph), 130.2 (Ph), 130.2 (Ph), 129.2 (Ph), 129.3 (Ph),
128.7 (Ph), 128.7 (Ph), 127.6 (Ph), 127.4 (Ph), 89.2 (C–H
pyrimidine); FAB-MS: m/z (M??1) 282.81 calc. 281.74.
propen-1-ones (1a–10a)
1,3-diaryl-2-propen-1-ones (1a–10a) were synthesised by
means of Claisen–Schmidt condensation (Li et al., 1995).
General procedure for preparation of 4,6-disubstituted
aminopyrimidines (1b–10b)
4-(2-Chlorophenyl)-6-(4-chlorophenyl) pyrimidin-
To a solution of guanidine hydrochloride (1.1 equiv.) in
50 mL isopropanol, sodium metal (1.1 equiv.) was added.
The reaction mixture was heated under reflux for 2 h, and
the different 1,3-diaryl-2-propen-1-ones (1.0 equiv.) were
added to it and further heated under reflux for 8 h. The
solvent was removed from reaction mixture in vacuo.
Water was added and the aqueous phase was extracted with
chloroform. The organic phase was dried over anhydrous
Na2SO4, filtered and concentrated. The crude product was
purified by crystallization from ethanol or sometimes by
column chromatography on silica gel (2 % methanol in
chloroform) to furnish the pure compounds.
2-amine (4b)
Yield: 88 %; m.p. 66 °C. Anal. Calc. for (C16H11Cl2N3): C
60.78, H 3.51, N 13.29 %; Found: C 60.88, H 3.42, N
13.35 %; IR: mmax(cm-1): 3418 (NH2), 1515, 1436 (C=N);
1H NMR (CDCl3): (d, ppm): 5.23 (s, 2H, NH2), 7.47 (s, 1H,
Ar–H), 7.21–7.23 (m, 4H, Ar–H), 7.09 (d, 2H, J = 7.2 Hz,
Ar–H), 7.12 (d, 2H, J = 7.2 Hz, Ar–H); 13C NMR
(CDCl3): (d, ppm): 165.1 (C=N pyrimidine), 164.6 (C=C
pyrimidine), 163.9 (N=C–N pyrimidine), 133.3 (Ph), 132.3
(Ph), 131.2 (Ph), 130.2 (Ph), 130.0 (Ph), 129.5 (Ph), 129.3
(Ph), 128.5 (Ph), 127.7 (Ph), 127.4 (Ph), 98.3 (C–H
pyrimidine); FAB-MS: m/z (M??1) 317.43 calc. 316.18.
4,6-Diphenylpyrimidin-2-amine (1b)
Yield:80 %;m.p. 82 °C. Anal. Calc. for(C16H13N3):C 77.71,
H 5.30, N16.99 %; Found: C 77.72, H 5.32, N 16.97 %; IR:
4-(3-Chlorophenyl)-6-phenylpyrimidin-2-amine (5b)
m
max(cm-1): 3393 (NH2), 1536, 1480 (C=N); 1H NMR
Yield: 68 %; m.p. 72 °C. Anal. Calc. for (C16H12ClN3): C
68.2, H 4.29, N 14.9 %; Found: C 68.2, H 4.32, N 14.3 %;
(CDCl3): (d, ppm): 5.12 (s, 2H, NH2), 7.23(s, 1H, Ar–H), 7.81
(m,10H, Ar–H); 13C NMR (CDCl3): (d, ppm): 163.6 (C=N
pyrimidine), 163.2 (C=C pyrimidine) 162.0 (N=C–N pyrim-
idine), 134.2 (Ph), 133.2 (Ph), 129.1(Ph), 129.1 (Ph), 128.8
(Ph), 127.6, (Ph) 126.9 (Ph), 126.8 (Ph), 96.0 (C–H pyrimi-
dine); FAB-MS: m/z (M??1) 248.34 calc. 247.29.
1
IR: mmax(cm-1): 3394(NH2),1525, 1459 (C=N); H NMR
(CDCl3): (d, ppm): 5.28 (s, 2H, NH2), 7.41 (s, 1H, Ar–H),
7.70–7.74 (m, 5H, Ar–H), 7.08 (s, 1H, Ar–H), 7.11 (d, 1H,
J = 7.3 Hz, Ar–H), 7.13 (dd, 1H, Ar–H), 7.11 (d, 1H,
J = 7.3 Hz, Ar–H); 13C NMR (CDCl3): (d, ppm): 164.6
(C=N pyrimidine), 163.9 (C=C pyrimidine), 163.1 (N=C–
N pyrimidine), 133.8 (Ph), 133.1 (Ph), 132.1 (Ph), 130.7
(Ph), 129.2 (Ph), 129.1 (Ph), 128.1 (Ph), 127.3 (Ph), 126.9
(Ph), 125.6 (Ph), 93.1 (C–H pyrimidine); FAB-MS: m/z
(M??1) 282.96 calc. 281.74.
4-(4-Chlorophenyl)-6-phenylpyrimidine-2-amine (2b)
Yield: 76 %; m.p. 98 °C. Anal. Calc. for (C16H12ClN3): C
68.21, H 4.29, N 14.91 %; Found: C 68.22, H 4.29, N
123

Med Chem Res
4-(3-Chlorophenyl)-6-(4-chlorophenyl) pyrimidin-
163.6 (C=C pyrimidine), 161.1 (N=C–N pyrimidine),
133.9 (Ph), 133.4 (Ph), 132.5 (Ph), 132.3 (Ph), 130.7 (Ph),
129.1 (Ph), 128.7 (Ph), 127.9 (Ph), 127.6 (Ph), 95.0 (C–H
pyrimidine); FAB-MS: m/z (M??1) 318.72 calc. 316.18.
2-amine (6b)
Yield: 88 %; m.p. 80 °C. Anal. Calc. for (C16H11Cl2N3): C
60.78, H 3.51, N 13.29 %; Found: C 60.97, H 3.32, N
13.39 %; IR: mmax(cm-1): 3310 (NH2), 1535, 1486 (C=N);
1H NMR (CDCl3): (d, ppm): 5.39 (s, 2H, NH2), 7.41 (s, 1H,
Ar–H), 7.23 (d, 2H, J = 7.2 Ar–H), 7.14 (d, 2H,
J = 7.2 Hz, Ar–H), 7.12 (s, 1H, Ar–H), 7.11 (d, 1H,
J = 7.1 Hz, Ar–H), 7.18 (dd, 1H, Ar–H), 7.18 (d, 1H,
J = 7.1 Hz, Ar–H); 13C NMR (CDCl3): (d, ppm): 163.9
(C=N pyrimidine), 162.1 (C=C pyrimidine), 160.4 (N=C–
N pyrimidine), 136.1 (Ph), 134.7 (Ph), 134.3 (Ph), 131.3
(Ph), 130.7 (Ph), 129.7 (Ph), 128.7 (Ph), 128.3 (Ph), 127.4
(Ph), 125.6 (Ph), 95.3 (C–H pyrimidine); FAB-MS: m/z
(M??1) 317.76 calc. 316.18.
4-(3,4-Dichlorophenyl)-6-(4-chlorophenyl)pyrimidin-
2-amine (10b)
Yield: 83 %; m.p. 111 °C. Anal. Calc. for (C16 H10Cl3N3):
C 54.81, H 2.87, N 11.98 %; Found: C 54.76, H 2.85, N
11.98 %; IR: mmax(cm-1): 3486 (NH2), 1561, 1461 (C=N);
1H NMR (CDCl3): (d, ppm): 5.31 (s, 2H, NH2), 7.53 (s, 1H,
Ar–H), 7.32 (d, 1H, J = 7.2 Hz, Ar–H), 7.34 (d, 1H,
J = 7.2, Ar–H), 7.17 (s, 1H, Ar–H), 7.11 (d, 2H,
J = 7.3 Hz, Ar–H), 7.15 (d, 2H, J = 7.3 Hz, Ar–H); 13C
NMR (CDCl3): (d, ppm): 164.4 (C=N pyrimidine), 163.3
(C=C pyrimidine), 160.4 (N=C–N pyrimidine), 134.3 (Ph),
133.8 (Ph), 133.5 (Ph), 132.5 (Ph), 131.2 (Ph), 130.8 (Ph),
129.3 (Ph), 128.9 (Ph), 128.8 (Ph), 127.4 (Ph), 95.5 (C–H
pyrimidine); FAB-MS: m/z (M??1) 351.87 calc. 350.63.
4-(4-Chlorophenyl)-6-phenylpyrimidin-2-amine (7b)
Yield: 53 %; m.p. 98 °C. Anal. Calc. for (C16H12ClN3): C
68.21, H 4.29, N 14.91 %; Found: C 68.35, H 4.36, N
14.91 %; IR: mmax(cm-1): 3328 (NH2), 1511, 1457 (C=N);
1H NMR (CDCl3): (d, ppm): 5.26 (s, 2H, NH2), 7.65 (s, 1H,
Ar–H), 7.41–7.45 (m, 5H, Ar–H), 6.93 (d, 2H, J = 7.4 Hz,
Ar–H), 7.21 (d, 2H, J = 7.4 Hz, Ar–H); 13C NMR (CDCl3):
(d, ppm): 165.2 (C=N pyrimidine), 163.1 (C=C pyrimidine),
162.9 (N=C–N pyrimidine), 134.3 (Ph), 134.1 (Ph), 129.4
(Ph), 128.9 (Ph), 128.8 (Ph), 128.6 (Ph), 127.6 (Ph), 97.3 (C–
H pyrimidine); FAB-MS: m/z (M??1) 282.77 calc. 281.74.
General procedure for preparation of sulphonamide
derivatives of 4,6-disubstituted aminopyrimidines
(1–20)
1 g of 4,6-disubstituted aminopyrimidines (1b–10b) was
treated with 4 molar equivalents of 10 % sodium hydroxide
solution. 1.5 mol of benzenesulphonyl or toluene-p-sul-
phonyl chloride was added in small portions with constant
stirring. The mixture was warmed gently to remove the
excess of acid chloride and then acidified with dilute
hydrochloric acid to precipitate the sulphonamides (1–20).
Solid obtained was recrystallised from ethanol.
4,6-Bis(4-chlorophenyl)pyrimidine-2-amine (8b)
Yield: 65 %; m.p. 102 °C. Anal. Calc. for (C16 H11Cl2N3): C
60.78, H 3.51, N 13.29 %; Found: C 60.67, H 3.49, N
13.46 %; IR: mmax(cm-1): 3409 (NH2), 1533, 1462 (C=N);
1H NMR (CDCl3): (d, ppm): 5.47 (s, 2H, NH2), 7.52 (s, 1H,
Ar–H), 7.11 (d, 2H, J = 7.2, Ar–H), 7.12 (d, 2H,
J = 7.2 Hz, Ar–H), 7.21 (d, 2H,J = 7.4, Ar–H), 7.26 (d, 2H,
J = 7.4 Hz, Ar–H); 13C NMR (CDCl3): (d, ppm): 163.2
(C=N pyrimidine), 162.9 (C=C pyrimidine), 162.1 (N=C–N
pyrimidine), 134.2 (Ph), 133.9 (Ph), 131.2 (Ph), 131.2 (Ph),
129.2 (Ph), 128.9 (Ph), 128.9 (Ph), 128.6 (Ph), 98.5 (C–H
pyrimidine); FAB-MS: m/z (M??1) 317.75 calc. 316.18.
N-(4,6-Diphenylpyrimidine-2-yl)benzenesulphonamide (1)
Yield: 71 %; m.p. 119 °C. Anal.Calc. for (C22H17N3O2S): C
68.20, H 4.42, N 10.85 %; Found: C 68.34, H 4.48, N
10.85 %; IR : mmax(cm-1): 3249 (NH), 1570 asym(SO2), 1025
sym(SO2); 1H NMR (DMSO-d6): d/ppm: 10.07 (s, 1H, NH),
7.21–7.34 (m, 5H, SO2–Ar–H); 13C NMR (DMSO-d6): d/
ppm:164.7(C=Npyrimidine), 162.6(C=Cpyrimidine), 159.2
(N=C–Npyrimidine), 132.1 (SO2–Ar–C), 131.1 (SO2–Ar–C),
129.7 (SO2–Ar–C), 124.6 (SO2–Ar–C), 96.5 (C–H pyrimi-
dine); FAB-MS: m/z (M??1) 388.56 calc. 387.45.
4-(3,4-Dichlorophenyl)-6-phenylpyrimidin-2-amine (9b)
Yield: 61 %; m.p. 101 °C. Anal. Calc. for (C16H11Cl2N3):
C 60.78, H 3.51, N 13.29 %; Found: C 60.77, H 3.49, N
13.31 %; IR: mmax(cm-1): 3328 (NH2), 1524, 1443 (C=N);
1H NMR (CDCl3): (d, ppm): 5.22 (s, 2H, NH2), 7.49 (s, 1H,
Ar–H), 7.52–7.57 (m, 1H, Ar–H), 7.21 (s, 1H, Ar–H), 7.24
(d, 2H, J = 7.3, Ar–H), 7.28 (d, 2H, J = 7.3 Hz, Ar–H);
13C NMR (CDCl3): (d, ppm): 163.7 (C=N pyrimidine),
N-(4,6-Diphenylpyrimidin-2-yl)-4-
methylbenzenesulphonamide (2)
Yield: 74 %; m.p. 95 °C. Anal.Calc. for (C23H19N3O2S): C
68.81, H 4.77, N 10.47 %; Found: C 68.84, H 4.874, N
10.52 %; IR : mmax(cm-1): 3613 (NH), 1508 asy(SO2), 1024
sy(SO2); 1HNMR(DMSO-d6):d/ppm: 10.11(s, 1H, NH), 7.31
123

Med Chem Res
(d, 2H, J = 7.4 Hz, SO2–Ar–H), 7.45 (d, 2H, J = 7.4 Hz,
SO2–Ar–H), 2.3 (s, 3H, CH3); 13C NMR (DMSO-d6): d/ppm:
169.9 (C=N pyrimidine), 163.4 (C=C pyrimidine), 162.5
(N=C–Npyrimidine), 142.3 (SO2–Ar–C), 131.7 (SO2–Ar–C),
123.7 (SO2–Ar–C), 127.7 (SO2–Ar–C), 86.8 (C–H pyrimi-
dine), 24.3(CH3); FAB-MS: m/z (M??1) 402.56 calc.401.48.
1H NMR (DMSO-d6): d/ppm:12.30 (s, 1H, NH), 6.98 (d, 2H,
J = 7.5 Hz, SO2–Ar–H), 6.98 (d, 2H, J = 7.5 Hz, SO2–Ar–
H), 2.9(s, 3H, CH3); 13C NMR (DMSO-d6): d/ppm: 173.3
(C=N pyrimidine), 162.4 (C=C pyrimidine), 161.7 (N=C–N
pyrimidine), 142.1 (SO2–Ar–C), 136.5 (SO2–Ar–C), 126.7
(SO2–Ar–C), 124.1 (SO2–Ar–C), 94.7 (C–H pyrimidine),
25.6 (CH3); FAB-MS: m/z (M??1) 437.01 calc. 435.92.
N-[4-(4-Chlrophenyl)-6-phenylpyrimidine-
2-yl]benzenesulphonamide (3)
N-[4-(2-Chlorophenyl)-6-(4-chlorophenyl)pyrimidin-
2-yl]-benzenesulphonamide (7)
Yield: 53 %; m.p. 120 °C. Anal.Calc. for (C22H16ClN3O2S):
C 62.63, H 3.82, N 9.96 %; Found: C 62.82, H 3.87, N
9.84 %; IR : mmax(cm-1): 3350 (NH), 1372 asym(SO2), 1102
sym(SO2); 1H NMR (DMSO-d6): d/ppm: 11.12 (s, 1H, NH),
7.6-7.7(m, 5H, SO2–Ar–H); 13C NMR (DMSO-d6): d/ppm:
162.6 (C=N pyrimidine), 161.6 (C=C pyrimidine), 159.2
(N=C–N pyrimidine), 135.9 (SO2–Ar–C), 132.3 (SO2–Ar–
C), 127.3 (SO2–Ar–C), 124.8 (SO2–Ar–C), 89.4 (C–H
pyrimidine); FAB-MS: m/z (M??1) 422.93 calc. 421.89.
Yield: 73 %; m.p. 110 °C. Anal.Calc. for (C22H15Cl2N3O2S):
C 57.90,H 3.31, N9.21 %;Found:C57.81,H 3.49, N9.22 %;
IR : mmax(cm-1): 2928 (NH), 1380 asym(SO2), 1053 sym(SO2);
1H NMR (DMSO-d6): d/ppm: 10.76 (s, 1H, NH), 7.26–7.37
(m, 5H, SO2–Ar–H); 13C NMR (DMSO-d6): d/ppm: 176.1
(C=N pyrimidine), 165.3 (C=C pyrimidine), 161.1 (N=C–N
pyrimidine), 135.7 (SO2–Ar–C), 132.9 (SO2–Ar–C), 130.8
(SO2–Ar–C), 125.5 (SO2–Ar–C), 97.6 (C–H pyrimidine);
FAB-MS: m/z (M??1) 457.41 calc.456.34.
N-[4-(4-Chlrophenyl)-6-phenylpyrimidine-
2-yl]-4-methylbenzenesulphonamide (4)
N-[4-(2-Chlrophenyl)-6-(4-chlorophenyl)pyrimidine-
2-yl]-4-methylbenzenesulphonamide (8)
Yield: 58 %; m.p. 94 °C. Anal.Calc. for (C23H18ClN3O2S): C
63.37, H 4.16, N 9.64 %; Found: C 63.56, H 4.16, N 9.53 %;
IR : mmax(cm-1): 3691 (NH), 1538 asym(SO2), 1035 sym(SO2);
1H NMR (DMSO-d6): d/ppm: 11.32 (s, 1H, NH), 7.35 (d, 2H,
J = 7.6 Hz, SO2–Ar–H), 7.39 (d, 2H, J = 7.6 Hz, SO2–Ar–
H), 2.5(s, 3H, CH3); 13C NMR (DMSO-d6): d/ppm: 178.1
(C=N pyrimidine), 167.4 (C=C pyrimidine), 164.6 (N=C–N
pyrimidine), 143.6 (SO2–Ar–C), 134.7 (SO2–Ar–C), 126.9
(SO2–Ar–C), 123.5 (SO2–Ar–C), 97.8 (C–H pyrimidine),
23.9 (CH3); FAB-MS: m/z (M??1) 436.88 calc. 435.92.
Yield: 85 %; m.p. 123 °C. Anal.Calc. for (C23H17Cl2N3O2S):
C 58.73,H 3.64, N8.94 %;Found:C58.86,H 3.64, N8.75 %;
IR : mmax(cm-1): 3274 (NH), 1560 asym(SO2), 1048 sym(SO2);
1H NMR (DMSO-d6): d/ppm:11.01 (s, 1H, NH), 7.04 (d, 2H,
J = 7.6 Hz, SO2–Ar–H), 7.06 (d, 2H, J = 7.6 Hz, SO2–Ar–
H), 2.4 (s, 3H, CH3); 13C NMR (DMSO-d6): d/ppm: 171.7
(C=N pyrimidine), 165.8 (C=C pyrimidine), 162.6 (N=C–N
pyrimidine), 141.7 (SO2–Ar–C), 136.4 (SO2–Ar–C), 129.2
(SO2–Ar–C), 127.3 (SO2–Ar–C), 97.1 (C–H pyrimidine),
27.1 (CH3); FAB-MS: m/z (M??1) 471.46 calc. 470.37.
N-[4-(2-Chlorophenyl)-6-phenylpyrimidin-
2-yl]-benzenesulphonamide (5)
N-[4-(3-Chlorophenyl)-6-phenylpyrimidine-
2-yl]benzenesulphonamide (9)
Yield: 59 %; m.p. 106 °C. Anal.Calc. for (C22H16ClN3O2S):
C 62.63,H 3.82, N9.96 %;Found:C62.71,H 3.82, N9.78 %;
IR : mmax(cm-1): 3524 (NH), 1334 asym(SO2), 1086 sym(SO2);
1H NMR (DMSO-d6): d/ppm: 10.67 (s, 1H, NH), 7.17-7.34
(m, 5H, SO2–Ar–H); 13C NMR (DMSO-d6): d/ppm: 166.3
(C=N pyrimidine), 163.3 (C=C pyrimidine), 161.9 (N=C–N
pyrimidine), 139.7 (SO2–Ar–C), 131.1 (SO2–Ar–C), 124.3
(SO2–Ar–C), 123.6 (SO2–Ar–C), 93.5 (C–H pyrimidine);
FAB-MS: m/z (M??1) 422.88 calc. 421.89.
Yield: 55 %; m.p. 79 °C. Anal.Calc. for (C22H16ClN3O2S): C
62.63, H 3.82, N 9.96 %; Found: C 62.65, H 3.74, N 9.81 %;
IR : mmax(cm-1): 3463 (NH), 1578 asym(SO2), 1026 sym(SO2);
1H NMR (DMSO-d6): d/ppm: 10.37 (s, 1H, NH), 7.48-7.58
(m, 5H, SO2–Ar–H); 13C NMR (DMSO-d6): d/ppm: 172.3
(C=N pyrimidine), 164.3 (C=C pyrimidine), 163.1 (N=C–N
pyrimidine), 135.9 (SO2–Ar–C), 132.5 (SO2–Ar–C), 130.7
(SO2–Ar–C), 128.4, (SO2–Ar–C), 95.4 (C–H pyrimidine);
FAB-MS: m/z (M??1) 422.95 calc. 421.89.
N-[4-(2-Chlrophenyl)-6-phenylpyrimidine-2-yl]-
4-methylbenzenesulphonamide (6)
N-[4-(3-Chlrophenyl)-6-phenylpyrimidine-2-yl]-
4-methylbenzenesulphonamide (10)
Yield: 61 %; m.p. 98 °C. Anal.Calc. for (C23H18ClN3O2S): C
63.37, H 4.16, N 9.64 %; Found: C 63.46, H 4.13, N 9.66 %;
IR : mmax(cm-1): 3601 (NH), 1401 asym(SO2), 1124 sym(SO2);
Yield: 80 %; m.p. 78 °C. Anal.Calc. for (C23H18ClN3O2S):
C 63.37, H 4.16, N 9.64 %; Found: C 63.31, H 4.19, N
123

Med Chem Res
9.59 %; IR : mmax(cm-1): 2985 (NH), 1469 asym(SO2), 1017
sym(SO2); 1H NMR (DMSO-d6): d/ppm:10.47 (s, 1H, NH),
7.21 (d, 2H, J = 7.4 Hz, SO2–Ar–H), 7.29 (d, 2H,
J = 7.4 Hz, SO2–Ar–H), 2.2(s, 3H, CH3); 13C NMR
(DMSO-d6): d/ppm: 171.5 (C=N pyrimidine), 164.7 (C=C
pyrimidine), 162.6 (N=C–N pyrimidine), 141.7 (SO2–Ar–
C), 131.3 (SO2–Ar–C), 129.4 (SO2–Ar–C), 127.2 (SO2–
Ar–C), 94.1 (C–H pyrimidine), 23.01 (CH3); FAB-MS: m/z
(M??1) 436.99 calc. 435.92.
N-[4-(4-Chlrophenyl)-6-phenylpyrimidine-2-yl]-
4-methylbenzenesulphonamide (14)
Yield: 46 %; m.p. 95 °C. Anal.Calc. for (C23H18ClN3O2S):
C 63.37, H 4.16, N 9.64 %; Found: C 63.45, H 4.16, N
9.79 %; IR : mmax(cm-1): 3561 (NH), 1393 asym(SO2), 1119
sym(SO2); 1H NMR (DMSO-d6): d/ppm: 11.23 (s, 1H, NH),
6.61 (d, 2H, J = 7.5 Hz, SO2–Ar–H), 6.79 (d, 2H,
J = 7.5 Hz, SO2–Ar–H), 2.2(s, 3H, CH3); 13C NMR
(DMSO-d6): d/ppm: 168.6 (C=N pyrimidine), 163.3 (C=C
pyrimidine), 161.4 (N=C–N pyrimidine), 142.6 (SO2–Ar–
C), 136.1 (SO2–Ar–C), 130.5 (SO2–Ar–C), 127.6 (SO2–
Ar–C), 94.8 (C–H pyrimidine), 24.7 (CH3); FAB-MS: m/z
(M??1) 436.96 calc. 435.92.
N-[4-(2-Chlorophenyl)-6-(4-chlorophenyl)pyrimidin-
2-yl]-benzenesulphonamide (11)
Yield: 79 %; m.p. 140 °C. Anal.Calc. for (C22H15Cl2
N3O2S): C 57.90, H 3.31, N 9.21 %; Found: C 57.76, H
3.44, N 9.34 %IR : mmax(cm-1): 3467 (NH), 1632
N-[4-(6-Bis(4-chlorophenyl)pyrimidin-
1
2-yl]-benzenesulphonamide (15)
asym(SO2), 1174 sym(SO2); H NMR (DMSO-d6): d/ppm:
10.93 (s, 1H, NH), 7.32–7.41 (m, 5H, SO2–Ar–H); 13C
NMR (DMSO-d6): d/ppm: 171.1 (C=N pyrimidine), 165.1
(C=C pyrimidine), 163.2 (N=C–N pyrimidine), 132.8
(SO2–Ar–C), 132.4 (SO2–Ar–C), 130.3 (SO2–Ar–C), 126.8
(SO2–Ar–C), 95.4 (C–H pyrimidine); FAB-MS: m/z
(M??1) 457.45 calc.456.34.
Yield: 67 %; m.p. 120 °C. Anal.Calc. for (C22H15Cl2N3
O2S): C 57.90; H 3.31; N 9.21 %; Found: C 57.91; H 3.42;
N 9.36 %; IR : mmax(cm-1): 3664 (NH), 1358 asym(SO2),
1011 sym(SO2); 1H NMR (DMSO-d6): d/ppm: 10.86 (s, 1H,
NH), 7.34-7.45 (m, 5H, SO2–Ar–H); 13C NMR (DMSO-
d6): d/ppm: 170.5 (C=N pyrimidine), 164.7 (C=C pyrimi-
dine), 162.8 (N=C–N pyrimidine), 132.9 (SO2–Ar–C),
131.8 (SO2–Ar–C), 130.1 (SO2–Ar–C), 125.3 (SO2–Ar–C),
95.4 (C–H pyrimidine); FAB-MS: m/z (M??1) 457.49
calc. 456.34.
N-[4-(3-Chlrophenyl)-6-(4-chlorophenyl)pyrimidine-
2-yl]-4-methylbenzenesulphonamide (12)
Yield: 74 %; m.p. 110 °C. Anal.Calc. for (C23H17Cl2N3
O2S): C 58.73, H 3.64, N 8.94 %; Found: C 58.72, H 3.66, N
8.91 %; IR : mmax(cm-1): 3311 (NH), 1548 asym(SO2), 1087
N-[4,6-Bis(4-chlorophenyl)pyrimidine-
1
2-yl]-4-methylbenzenesulphonamide (16)
sym(SO2); H NMR (DMSO-d6): d/ppm:12.05 (s, 1H, NH),
7.49 (d, 2H, J = 7.3 Hz, SO2–Ar–H), 7.52 (d, 2H,
J = 7.3 Hz, SO2–Ar–H), 2.7 (s, 3H, CH3); 13C NMR
(DMSO-d6): d/ppm: 167.5 (C=N pyrimidine), 163.5 (C=C
pyrimidine), 161.3 (N=C–N pyrimidine), 141.6 (SO2–Ar–
C), 138.3 (SO2–Ar–C), 130.1 (SO2–Ar–C), 128.9 (SO2–Ar–
C), 95.3 (C–H pyrimidine), 26.1 (CH3); FAB-MS: m/z
(M??1) 471.49 calc. 470.37.
Yield: 59 %; m.p. 118 °C. Anal.Calc. for (C23H17Cl2N3
O2S): C 58.73, H 3.64, N 8.94 %; Found: C 58.83, H 3.48,
N 8.97 %; IR : mmax(cm-1): 3527 (NH), 1457 asym(SO2),
1073 sym(SO2); 1H NMR (DMSO-d6): d/ppm: 11.64 (s, 1H,
NH), 7.01 (d, 2H, J = 7.6 Hz, SO2–Ar–H), 7.09 (d, 2H,
J = 7.6 Hz, SO2–Ar–H), 2.1(s, 3H, CH3); 13C
NMR(DMSO-d6): d/ppm: 171.5 (C=N pyrimidine), 164.2
(C=C pyrimidine), 163.6 (N=C–N pyrimidine), 142.01
(SO2–Ar–C), 137.3 (SO2–Ar–C), 130.5 (SO2–Ar–C), 127.1
(SO2–Ar–C), 94.4 (C–H pyrimidine), 27.8 (CH3); FAB-
MS: m/z (M??1) 471.45 calc. 470.37.
N-[4-(4-Chlorophenyl)-6-phenylpyrimidine-
2-yl]benzenesulphonamide (13)
Yield: 87 %; m.p. 136 °C. Anal.Calc. for (C22H16ClN3
O2S): C 62.63, H 3.82, N 9.96 %; Found: C 62.68, H 3.88,
N 9.87 %; IR : mmax(cm-1): 3466 (NH), 1611 asym(SO2),
1152 sym(SO2); 1H NMR (DMSO-d6): d/ppm: 11.08 (s, 1H,
NH), 7.53-7.76 (m, 5H, SO2–Ar–H); 13C NMR(DMSO-d6):
d/ppm: 168.9 (C=N pyrimidine), 164.6 (C=C pyrimidine),
161.6 (N=C–N pyrimidine), 133.1 (SO2–Ar–C), 132.6
(SO2–Ar–C), 130.9 (SO2–Ar–C), 125.7 (SO2–Ar–C), 95.3
(C–H pyrimidine); FAB-MS: m/z (M??1) 423.01 calc.
421.89.
N-[4-(3,4-Dichlorophenyl)-6-phenylpyrimidin-
2-yl]-benzenesulphonamide (17)
Yield: 74 %; m.p. 105 °C. Anal.Calc. for (C22H15Cl2N3
O2S): C 57.90, H 3.31, N 9.21 %; Found: C 57.84, H 3.46,
N 9.42 %; IR : mmax(cm-1): 3609 (NH), 1396 asym(SO2),
1096 sym(SO2); 1H NMR (DMSO-d6): d/ppm: 12.36 (s, 1H,
NH), 7.71-7.65 (m, 5H, SO2–Ar–H); 13C NMR (DMSO-d6):
123

Med Chem Res
d/ppm: 168.4 (C=N pyrimidine), 164.4 (C=C pyrimidine),
162.01 (N=C–N pyrimidine), 133.2 (SO2–Ar–C), 132.3
(SO2–Ar–C), 130.6 (SO2–Ar–C), 129.9 (SO2–Ar–C), 95.3
(C–H pyrimidine); FAB-MS: m/z (M??1) 457.41 calc.
456.34.
by microdilution method (Wright et al., 1988). E. histolytica
trophozoites were cultured in culture tubes by using Dia-
mond TYIS-33 growth medium. The test compounds (1 mg)
were dissolved in DMSO (40 lL, level atwhich noinhibition
of amoeba occurs) (Gillin et al., 1982). The stock solutions of
the compounds were prepared freshly before the use at a
concentration of 1 mg/mL. Two-fold serial dilutions were
made in the wells of 96-well microtiter plate (costar). Each
test includes MNZ as a standard amoebicidal drug, control
wells (culture medium plus amoebae) and a blank (culture
medium only). All the experiments were carried out in trip-
licate at each concentration level and repeated thrice. The
amoeba suspension was prepared from a confluent culture by
pouring off the medium at 37 °C and adding 5 mL of fresh
medium, chilling the culture tube on ice to detach the
organisms from the side of flask. The number of amoeba/mL
was estimated with the help of a haemocytometer, using
trypan blue exclusion to confirm the viability. The suspen-
sion was diluted to 105 organism/mL by adding fresh med-
ium and 170 lL of this suspension was added to the test and
control wells in the plate, so that the wells were completely
filled (total volume, 340 mL). An inoculum of 1.7 9 104
organisms/well was chosen so that confluent, but not
excessive growth, took place in control wells. Plate was
sealed and gassed for 10 min with nitrogen before the
incubation at 37 °C for 72 h. After theincubation, the growth
of amoeba in the plate was checked with a low-power
microscope. The culture medium was removed by inverting
the plate and shaking gently. Plate was then immediately
washed with sodium chloride solution (0.9 %) at 37 °C. This
procedure was completed quickly and the plate was not
allowed to cool to prevent the detachment of amoeba. The
plate was allowed to dry at room temperature and the
amoebae were fixed with methanol, and when dried, stained
with (0.5 %) aqueous eosin for 15 min. The stained plate was
washed once with tap water, then twice with distilled water
and then allowed to dry. A 200 lL portion of 0.1 N sodium
hydroxide solution was added to each well to dissolve the
protein and release the dye. The optical density of the
resulting solution in each well was determined at 490 nm
with a microplate reader. The % inhibition of amoebal
growth was calculated from the optical densities of the
control and test wells and plotted against the logarithm of the
dose of the drug tested. Linear regression analysis was used
to determine the best fitting line from which the IC50 value
was found. The IC50 values are reported in Table 1 and 2.
N-[4-(3,4-Dichlorophenyl)-6-phenylpyrimidine-2-yl]-
4-methylbenzenesulphonamide (18)
Yield: 87 %; m.p. 87 °C. Anal.Calc. for (C23H17Cl2N3
O2S): C 58.73, H 3.64, N 8.94 %; Found: C 58.77; H 3.68;
N 8.94 %; IR : mmax(cm-1): 3124 (NH), 1583asym(SO2),
1
1145 sym(SO2); H NMR (DMSO-d6): d/ppm:12.15 (s, 1H,
NH), 6.88 (d, 2H, J = 7.7 Hz, SO2–Ar–H), 6.91 (d, 2H,
J = 7.7 Hz, SO2–Ar–H), 2.7(s, 3H, CH3); 13C NMR
(DMSO-d6): d/ppm: 168.4 (C=N pyrimidine), 163.6 (C=C
pyrimidine), 161.2 (N=C–N pyrimidine), 143.8 (SO2–Ar–
C), 139.2 (SO2–Ar–C), 130.2 (SO2–Ar–C), 125.8 (SO2–
Ar–C), 95.6 (C–H pyrimidine), 26.8 (CH3); FAB-MS: m/z
(M??1) 471.41 calc. 470.37.
N-[4-(4-Chlorophenyl)-6-(3,4-dichlorophenyl)pyrimidin-
2-yl]benzenesulphonamide (19)
Yield: 48 %; m.p. 112 °C. Anal.Calc. for (C22H14Cl3N3O2S):
C 53.84,H 2.88, N8.56 %;Found:C53.93,H 2.89, N8.56 %;
IR : mmax(cm-1): 3316 (NH), 1516 asym(SO2), 1178 sym(SO2);
1H NMR (DMSO-d6): d/ppm: 10.81 (s, 1H, NH), 7.61-7.74
(m, 5H, SO2–Ar–H); 13C NMR (DMSO-d6): d/ppm: 169.5
(C=N pyrimidine), 163.7 (C=C pyrimidine), 162.5 (N=C–N
pyrimidine), 135.8 (SO2–Ar–C), 132.1 (SO2–Ar–C), 131.1
(SO2–Ar–C), 129.8 (SO2–Ar–C), 95.6 (C–H pyrimidine);
FAB-MS: m/z (M??1) 491.83 calc. 490.78.
N-[4-(4-Chlorophenyl)-6-(3,4-dichlorophenyl)pyrimidin-
2-yl]-4-methylbenzenesulphonamide (20)
Yield: 71 %; m.p. 107 °C. Anal.Calc. for (C23H16Cl3N3O2S):
C 54.72,H 3.19, N8.32 %;Found:C54.85,H 3.14, N8.34 %;
IR : mmax(cm-1): 3568 (NH), 1619asym(SO2), 1024 sym(SO2);
1H NMR (DMSO-d6): d/ppm:11.45 (s, 1H, NH), 7.24 (d, 2H,
J = 7.3 Hz, SO2–Ar–H), 7.29 (d, 2H, J = 7.3 Hz, SO2–Ar–
H), 2.9 (s, 3H, CH3); 13C NMR(DMSO-d6): d/ppm: 173.6
(C=N pyrimidine), 163.2 (C=C pyrimidine), 161.7 (N=C–N
pyrimidine), 143.8 (SO2–Ar–C), 139.2 (SO2–Ar–C), 130.2
(SO2–Ar–C), 125.8 (SO2–Ar–C), 95.2 (C–H pyrimidine),
26.8 (CH3); FAB-MS: m/z (M??1) 503.93 calc. 504.81.
Conclusion
In vitro anti-amoebic assay
In the present study, we synthesized 4,6-disubstituted am-
inopyrimidines (1b–10b) and their sulphonamide deriva-
tives (1–20) to evaluate their in vitro anti-amoebic activity
All the desired compounds were screened for in vitro anti-
amoebic activity against HM1:IMSS strain of E. histolytica
123

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