Design and synthesis of novel N-substituted-3-chloro-2- azetidinone derivatives as potential anticonvulsant agents

Article abstract of DOI:10.1007/s00044-010-9485-0

A new series of N-[3-chloro-2-(substitutedphenyl)-oxo-azetidin-1-yl] isonicotinamide (2a-l) were synthesized through condensation reaction of isoniazide with substituted aldehyde. The newly synthesized compounds ere characterized by spectral data (IR,

Full text of DOI:10.1007/s00044-010-9485-0

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2011) 20:1357–1363
DOI 10.1007/s00044-010-9485-0
ORIGINAL RESEARCH
Design and synthesis of novel N-substituted-3-chloro-2-
azetidinone derivatives as potential anticonvulsant agents
•
Hozaifa Hasan Maymoona Akhter Wasim Akhter
•
•
•
•
•
Israr Ali Mohd. Zaheen Iftikhar Ahsan
Danish Mahmood
Received: 30 January 2010 / Accepted: 19 October 2010 / Published online: 10 November 2010
Ó Springer Science+Business Media, LLC 2010
Abstract A new series of N-[3-chloro-2-(substitutedphe-
nyl)-4-oxo-azetidin-1-yl]isonicotinamide (2a–l) were syn-
thesized through condensation reaction of isoniazide with
substituted aldehyde. The newly synthesized compounds
2-Azetidinones, commonly known as b-lactams, are
heterocyclic compounds well known to organic and
medicinal chemists. The activities of widely used antibi-
otics such as penicillins, cephalosporins, and carbapenems
are attributed to the presence of 2-azetidinone ring (Singh,
2004). Literature survey reveals that beside their antibac-
terial activity (Patel and Mehta, 2006) 2-azetidinones also
possess various biological activities that include anticon-
vulsant (El-Helby and Wahab, 2003), carbonic anhydrase
inhibition (Russo et al., 1994), local anesthetic (Costakes
and Tsatsa, 1978), hypoglycemic (Chernykh and Sid-
orenko, 1981), and anti-inflammatory (Sreenivasa et al.,
2005). The b-lactams also serve as synthons for many
biologically important classes of organic compounds
(Deshmukh et al., 2004). Thus, various activities attributed
to 2-azetidinone ring hold the potential in the development
of novel antiepileptic agents (Singh, 2004). Therefore, the
potential therapeutic importance of azetidinone rings
prompted us to develop selective molecules in which a
substituent could be arranged in a pharmacophoric pattern
to display higher pharmacological activities.
1
were characterized by spectral data (IR, H NMR, mass
spectra) and elemental analysis. Compound 2e exhibited
excellent anticonvulsant activity and no neurotoxicity in
comparison to reference drug phenytoin.
Keywords Azetidinone Á MES Á PTZ Á Neurotoxicity Á
CNS depressant
Introduction
Epilepsy, an ubiquitous disease characterized by recurrent
seizures that affects more than 60 million people world-
wide and 2.5 million people in USA, according to epide-
miological studies (Wasterlain et al., 1989; Loscher, 1998).
Drugs presently available in the market for the treatment of
epilepsy do not provide a complete cure and have an effect
only in 60–70% of patients. Moreover, these drugs cause
various side effects such as drowsiness, gastrointestinal
disturbance, hepatotoxicity, and megaloblastic anemia
(Perucca, 1996; Lin and Kadaba, 1997), including some
life-threatening conditions (Al-Soud et al., 2003).
Result and discussion
Synthesis
The most common method for the synthesis of 2-azetidi-
nones is the Staudinger keteneimine cycloaddition, which
involves the reaction of imines with acid chloride in the
presence of a tertiary base (Staudinger, 1907). In the present
work, we have synthesized N-[3-chloro-2-(substitutedphe-
nyl)-4-oxo-azetidin-1-yl]isonicotinamide (2a–l) in a two-
step procedure, as shown in Scheme 1. Various isonicotinic
acids (substituted-benzylidene)-hydrazide (1a–l) were
H. Hasan (&) Á M. Akhter Á W. Akhter Á I. Ali Á
Mohd. Zaheen Á I. Ahsan
Department of Pharmaceutical Chemistry, Faculty of Pharmacy,
Hamdard University, New Delhi 110062, India
e-mail: hozaifa4hasan@gmail.com
D. Mahmood
Department of Pharmacology, Faculty of Pharmacy, Hamdard
University, New Delhi 110062, India
123

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Med Chem Res (2011) 20:1357–1363
(Z)
N
NH2
NH
R
O
R
CHO
R
O
NH
Cl
ClCH2COCl
TEA/DMF
EtOH
GAA
O
+
N
N
O
HN
N
N
2a-l
1a-l
Scheme 1 Protocol for synthesis of N-[3-chloro-2-(substitutedphenyl)-4-oxo-azetidin-1-yl]isonicotinamide derivatives. R: a = 4-OH,
b = 2-OH, c = 2-OCH3, d = 4-N(CH3)2, e = 4-CH3, f = 3,4-di-OCH3, g = 3-OCH3-4OH, i = 2-NO2, j = 4-Cl, k = 2-Cl, l = H
synthesized by treating isonicotinohydrazide with different
substituted benzaldehydes in absolute ethanol. Compounds
(1a–l) were refluxed with triethylamine and chloroacetal-
dehyde to form N-[3-chloro-2-(substitutedphenyl-4-oxo-
azetidin-1-yl]isonicotinamides (2a–l) in moderate to good
yields (60–80%). Thin layer chromatography (TLC) was
used throughout to monitor and optimize the reactions for
purity and completion. Synthesized compounds were char-
acterized by IR, 1H NMR, mass spectroscopy, and elemental
analysis.
was observed. It was found that the azetidinone derivatives
having CH3 group showed maximum anticonvulsant
activity in comparison to OH, OCH3, NO2, N(CH3)2,
Cl, and H group/atom on the whole level. The position
of the substituents on the phenyl ring greatly influenced
the anticonvulsant activity, the activity order is p [
p–m [ o. The p-CH3 derivative 2e exhibited the highest at
minimum dose 30 mg/kg in maximum electroshock seizure
(MES) at both 0.5 and 4.0 h and 100 and 30 mg/kg, i.p. in
subcutaneous pentylenetetrazole (scPTZ) at 0.5 and 4.0 h,
respectively. The ortho and meta derivative 2f and 2g
exhibited weaker activity than para substituted derivatives
2a, 2d, 2e, 2h, and 2j. In this series, most of the tested
compounds showed no neurotoxicity except for compounds
2a and 2h, which showed neurotoxicity at the highest dose
(300 mg/kg) after 4.0 h, possibly because the presence of
highly polar group at para position.
Pharmacology
All newly synthesized compounds were evaluated for their
anticonvulsant activity. Neurotoxicity and antidepressant
activity are shown in Tables 1 and 2. Most of the com-
pounds showed significant anticonvulsant activity, except
for ortho derivatives 2b, 2c, and 2k (no anticonvulsant
activity at dosages up to 100 mg/kg, i.p.). One can suppose
that ortho substituent may possibly block the azetidinone
ring receptor interaction.
Compound 2d, 2e, 2f, 2j, and 2l showed significant
anticonvulsant activity and were also tested for their CNS
depressant effect (Table 2). The tested compounds showed
49.8, 21.6, 33.8, 54.5, and 11.5% increase in immobility
time with respect to controls whereas the standard drug
carbamazepine showed 30.6% increase in the immobility
Analyzing the activities of all synthesized derivatives
2a–l, the following structure–activity relationship (SAR)
Table 1 Anticonvulsant and
Compound
R
MESa
0.5 h
PTZa
0.5 h
Neurotoxicitya
neurotoxicity screening of
N-substituted-3-chloro-2-
azetidinones
4.0 h
4.0 h
0.5 h
4.0 h
2a
4-OH
–
100
300
300
100
30
–
300
–
–
300
–
2b
2-OH
–
–
–
2c
2-OCH3
4-N(CH3)2
4-CH3
–
–
–
–
–
2d
100
30
100
300
–
–
100
30
–
–
a
Doses of 30, 100, and 300
2e
100
100
–
–
–
mg/kg were administered, the
figures in the table indicate the
minimum dose whereby
bioactivity was demonstrated in
half or more of mice. The
animals were examined 0.5 and
4.0 h after injection was made.
The dash (–) indicates an
absence of activity at maximum
dose administered (300 mg/kg)
2f
3,4-Di-OCH3
3-OCH3, 4-OH
4-NO2
100
100
100
300
100
300
100
30
100
300
100
300
100
–
–
–
2g
–
–
2h
300
–
–
300
–
2i
2-NO2
–
–
2j
4-Cl
300
–
100
–
–
–
2k
2-Cl
–
–
2l
H
100
30
30
100
–
100
–
–
–
Phenytoinb
Carbamazepineb
100
–
100
30
b
Activity reported (show 100%
protection at respective dose)
100
100
300
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Med Chem Res (2011) 20:1357–1363
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Table 2 CNS depressant study
Compound
R
Duration of immobility (s)
(mean SEM)
Increased of
immobility (%)
on selected active compounds
by forced swim pool test
method
2d
4-N(CH3)2
4-CH3
102.83 1.49
75.16 1.16
87.33 0.66
110.50 0.76
65.50 0.73
84.16 0.47
53.5 0.42
49.83
21.66
33.83
54.54
11.50
30.66
–
2e
2f
3,4-Di-OCH3
4-Cl
2j
2l
H
Carbamazepine
Control
time, indicating a lower CNS depressant effect for com-
iodine vapors as visualizing agents. IR spectra were
obtained on a Perkin-Elmer 1720 FT-IR spectrometer
1
(KBr pellets). H NMR spectra were obtained on a Bruker
pounds 2e and 2l.
DRX-300 (300 MHz FT NMR) spectrometer in CDCl3
using tetramethylsilane (TMS) as the internal reference
(chemical shifts in d ppm). Elemental analysis (C, H, and N)
were undertaken with Perkin-Elmer model 240C analyzer.
Mass spectra were recorded at Jeol SX-102 spectrometer.
Conclusion
A series of N-[3-chloro-2-(substitutedphenyl)-4-oxo-azeti-
din-1-yl]isonicotinamide derivatives were synthesized. The
anticonvulsant effect and the neurotoxicity of the com-
pounds were calculated with MES test, Sc-PTZ, and rota-
rod tests with intraperitoneally injected mice. Among the
synthesized it was found that N-[3-chloro-2-(4-methyl-
phenyl)-4-oxoazetidin-1-yl]isonicotinamide (2e) possessed
significant anticonvulsant activity in comparison to stan-
dard drug phenytoin and carbamazepine (showed activity
at 30 mg/kg body weight without neurotoxicity). On the
basis of these results it can be concluded that the anti-
convulsant activity was affected by two factors. Firstly the
introduction of electron withdrawing/releasing groups,
where anticonvulsant activity decreases with the introduc-
tion of electron withdrawing groups like OH, NO2, Cl and
significant increases of anticonvulsant activity were
observed with the substitution of electron donating groups
like CH3, OCH3, N(CH3)2, and H. Moreover, the molecular
symmetry is the 2nd factor influencing the biological
activity because unsubstituted and para-substituted com-
pounds showed good activity as compared to ortho- and
meta-substituted compounds. Compound 2e showed
excellent anticonvulsant activity due to substitution of
electron releasing group (p-CH3) which increases the
lipophilicity and on the other hand, para substitution
facilitates molecule receptor interactions.
General procedure for synthesis of isonicotinic acid
(substituted-benzylidene)-hydrazide (1a–l)
To a solution of isoniazide (0.01 mol) in absolute ethanol
(30 ml) few drops of glacial acetic acid and substituted
benzaldehyde (0.01 mol) were added. The reaction mixture
was refluxed for 3 h on water bath. The reaction mixture
was poured onto crushed ice, a solid mass separated was
filtered, washed with water and recrystallized from ethanol.
Isonicotinic acid (4-hydroxy-benzylidene)-hydrazide (1a)
Yield 67%; m.p.: 242–245°C; IR (KBr, cm-1): 3546 (OH),
3447 (NH), 2917 (NCH), 1671 (C=O); H NMR (CDCl3),
1
d (ppm): 11.9 (bs, 1H, CONH), 9.31 (s, 1H, OH), 8.52 (s,
1H, N–CH), 8.1–8.4 (m, 4H, pyridine), 7.1–7.69 (m, 4H,
Ar–H); MS: m/z 241 (M?); Anal. Calcd for C13H11N3O2:
C, 64.72; H, 4.60; N, 17.42; Found: C, 64.61; H, 4.43; N,
17.48.
Isonicotinic acid (2-hydroxy-benzylidene)-hydrazide (1b)
Yield 73%; m.p.: 174–176°C; IR (KBr, cm-1): 3521 (OH),
3398 (NH), 2924 (NCH), 1676 (C=O); 1H NMR (CDCl3), d
(ppm): 10.03 (bs, 1H, CONH), 9.43 (s, 1H, OH), 8.34 (s, 1H,
N–CH), 7.64–7.91 (m, 4H, pyridine), 7.1–7.59 (m, 4H,
Ar–H); MS: m/z 241 (M?); Anal. Calcd for C13H11N3O2: C,
64.72; H, 4.60; N, 17.42; Found: C, 64.57; H, 4.42; N, 17.41.
Experimental
General chemistry
All chemicals used in the synthesis were supplied by E.
Merck and S.D. Fine Chemicals. Melting points are
determined by open capillary tube method and are uncor-
rected. Purity of the compound was checked on TLC using
Isonicotinic acid (2-methoxy-benzylidene)-hydrazide (1c)
Yield 70%; m.p.: 131–133°C; IR (KBr, cm-1): 3425 (NH),
1
3028 (NCH), 1668 (C=O); H NMR (CDCl3), d (ppm):
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Isonicotinic acid (2-nitro-benzylidene)-hydrazide (1i)
Yield 76%; m.p.: 123–125°C; IR (KBr, cm-1): 3464 (NH),
12.07 (bs, 1H, CONH), 8.7 (s, 1H, N–CH), 7.8–8.4 (m, 4H,
pyridine), 7.4–7.76 (m, 4H, Ar–H), 2.98 (s, 3H, OCH3);
MS: m/z 255 (M?); Anal. Calcd for C14H13N3O2: C, 65.87;
H, 5.13; N, 16.46; Found: C, 65.74; H, 5.02; N, 16.34.
1
3011 (NCH), 1673 (C=O); H NMR (CDCl3), d (ppm):
10.76 (bs, 1H, CONH), 8.56 (s, 1H, N–CH), 8.21–8.49 (m,
4H, CH-pyridine), 6.76–7.54 (m, 4H, Ar–H); MS: m/z 270
(M?); Anal. Calcd for C13H10N4O3: C, 57.78; H, 3.73; N,
20.73; Found: C, 57.69; H, 3.61; N, 20.59.
Isonicotinic acid (4-dimethylamino-benzylidene)-hydrazide
(1d)
Yield 75%; m.p.: 192–194°C; IR (KBr, cm-1): 3475 (NH),
1
Isonicotinic acid (4-chloro-benzylidene)-hydrazide (1j)
Yield 73%; m.p.: 225–227°C; IR (KBr, cm-1): 3399 (NH),
2969 (NCH), 1653 (C=O), 679 (C–Cl); H NMR (CDCl3),
3012 (NCH), 1659 (C=O); H NMR (CDCl3), d (ppm):
12.18 (bs, 1H, CONH), 8.3 (s, 1H, N–CH), 8.2–8.5 (m, 4H,
pyridine), 6.9–7.75 (m, 4H, Ar–H), 2.89 (s, 6H, 2CH3);
MS: m/z 268 (M?); Anal. Calcd for C15H16N4O: C, 67.15;
H, 6.01; N, 20.88; Found: C, 67.04; H, 6.11; N, 20.69.
1
d (ppm): 12.27 (bs, 1H, CONH), 8.52 (s, 1H, N–CH),
7.3–8.1 (m, 4H, pyridine), 6.91–7.73 (m, 4H, Ar–H); MS:
m/z 259 (M?), 261 (M??2); Anal. Calcd for
C13H10ClN3O: C, 60.12; H, 3.88; N, 16.18; Found: C,
60.01; H, 3.67; N, 16.04.
Isonicotinic acid (4-methyl-benzylidene)-hydrazide (1e)
Yield 70%; m.p.: 212–214°C; IR (KBr, cm-1): 3425 (NH),
1
3028 (NCH), 1668 (C=O); H NMR (CDCl3), d (ppm):
Isonicotinic acid (2-chloro-benzylidene)-hydrazide (1k)
Yield 67%; m.p.: 177–179°C; IR (KBr, cm-1): 3403 (NH),
2976 (NCH), 1643 (C=O), 674 (C–Cl); H NMR (CDCl3),
11.07 (bs, 1H, CONH), 8.6 (s, 1H, N–CH), 7.9–8.7 (m, 4H,
pyridine), 6.9–7.76 (m, 4H, Ar–H), 2.50 (s, 3H, CH3); MS:
m/z 239 (M?); Anal. Calcd for C14H13N3O: C, 70.28; H,
5.48; N, 17.56; Found: C, 70.18; H, 5.32; N, 17.35.
1
d (ppm): 12.07 (bs, 1H, CONH), 8.41 (s, 1H, N–CH),
7.3–8.0 (m, 4H, pyridine), 6.81–7.72 (m, 4H, Ar–H); MS:
m/z 259 (M?), 261 (M? ? 2); Anal. Calcd for
C13H10ClN3O: C, 60.12; H, 3.88; N, 16.18; Found: C,
59.97; H, 3.71; N, 16.21.
Isonicotinic acid (3,4-dimethoxy-benzylidene)-hydrazide
(1f)
Yield 68%; m.p.: 167–169°C; IR (KBr, cm-1): 3425 (NH),
3028 (NCH), 1679 (C=O); 1H NMR (CDCl3), d (ppm): 11.37
(bs, 1H, CONH), 8.51 (s, 1H, N–CH), 7.8–8.3 (m, 4H, pyr-
idine), 6.8–7.2 (m, 3H, Ar–H), 3.87 (s, 6H, 2OCH3); MS: m/z
285 (M?); Anal. Calcd for C15H15N3O3: C, 63.15; H, 5.30;
N, 14.73; Found: C, 62.98; H, 5.13; N, 14.58.
Isonicotinic acid benzylidene-hydrazide (1l)
Yield 72%; m.p.: 102–104°C; IR (KBr, cm-1): 3425 (NH),
1
3028 (NCH), 1668 (C=O); H NMR (CDCl3), d (ppm):
12.07 (bs, 1H, CONH), 7.95 (s, 1H, N–CH), 7.63–7.89 (m,
4H, pyridine), 6.92–7.75 (m, 5H, Ar–H); MS: m/z 225
(M?); Anal. Calcd for C13H11N3O: C, 69.32; H, 4.92; N,
18.66; Found: C, 69.17; H, 4.71; N, 18.54.
Isonicotinic acid (4-hydroxy-3-methoxy-benzylidene)-
hydrazide (1g)
Yield 65%; m.p.: 187–189°C; IR (KBr, cm-1): 3387 (NH),
1
General procedure for synthesis of N-[3-chloro-2-
(substitutedphenyl)-4-oxo-azetidin-1-
3087 (NCH), 1675 (C=O); H NMR (CDCl3), d (ppm):
12.25 (bs, 1H, CONH), 9.6 (s, 1H, OH), 8.42 (s, 1H,
N–CH), 7.6–8.2 (m, 4H, pyridine), 6.9–7.73 (m, 3H,
Ar–H), 3.76 (s, 3H, OCH3); MS: m/z 271 (M?); Anal.
Calcd for C14H13N3O3: C, 61.99; H, 4.83; N, 15.49; Found:
C, 61.83; H, 4.71; N, 15.29.
yl]isonicotinamide derivatives (2a–l)
A solution of coumpound 1a–l, triethylamine (0.02 mol) and
chloroacetylchloride (0.02 mol) in DMF (40 ml) was refluxed
for 3 h on water bath. The reaction mixture was poured onto
crushed ice, a solid mass separated out which was filtered,
washed with water and recrystallized from ethanol.
Isonicotinic acid (4-nitro-benzylidene)-hydrazide (1h)
Yield 75%; m.p.: 155–157°C; IR (KBr, cm-1): 3467 (NH),
1
N-[3-Chloro-2-(4-hydroxy-phenyl)-4-oxoazetidin-
1yl]isonicotinamide (2a)
3014 (NCH), 1678 (C=O); H NMR (CDCl3), d (ppm):
11.76 (bs, 1H, CONH), 8.32 (s, 1H, N–CH), 7.92–8.56 (m,
4H, CH-pyridine), 6.75–7.54 (m, 4H, Ar–H); MS: m/z 270
(M?); Anal. Calcd for C13H10N4O3: C, 57.78; H, 3.73; N,
20.73; Found: C, 57.65; H, 3.57; N, 20.58.
Yield 70%; m.p.: 292–294°C; IR (KBr, cm-1): 3425 (NH),
3019 (CH), 1671 (C=O), 657 (C–Cl); 1H NMR (CDCl3), d
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Med Chem Res (2011) 20:1357–1363
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N-[3-Chloro-2-(3,4-dimethoxyl-phenyl)-4-oxoazetidin-1-
yl]isonicotinamide (2f)
(ppm): 11.24 (bs, 1H, CONH), 9.32 (s, 1H, OH), 8.41–8.79
(m, 4H, pyridine), 7.67–7.98 (m, 4H, Ar–H), 7.13 (d, 1H,
N–CH), 5.49 (d, 1H, CH–Cl); MS: m/z 317 (M?), 319
(M? ? 2); Anal. Calcd for C15H12ClN3O3: C, 56.70; H,
3.81; N, 11.16; Found: C, 56.58; H, 3.69; N, 10.98.
Yield: 80%; m.p.: 180–182°C; IR (KBr, cm-1): 3416 (NH),
3021 (CH), 1674 (C=O), 665 (C–Cl); 1H NMR (CDCl3), d
(ppm): 12.07 (bs, 1H, CONH), 8.35 (d, 1H, N–CH),
7.79–8.11 (m, 4H, pyridine), 7.14–7.55 (m, 3H, Ar–H), 5.23
(d, 1H, CH–Cl), 3.79 (s, 6H, 2OCH3); MS: m/z 361 (M?),
363 (M? ? 2); Anal. Calcd for C17H16ClN3O4: C, 56.44; H,
4.46; N, 11.61; Found: C, 56.23; H, 4.28; N, 11.47.
N-[3-Chloro-2-(2-hydroxy-phenyl)-4-oxoazetidin-
1yl]isonicotinamide (2b)
Yield 73%; m.p.: 174–176°C; IR (KBr, cm-1): 3412 (NH),
3029 (CH), 1656 (C=O), 677 (C–Cl); 1H NMR (CDCl3), d
(ppm): 11.04 (bs, 1H, CONH), 9.21 (s, 1H, OH), 8.38–8.79
(m, 4H, pyridine), 7.77–7.93 (m, 4H, Ar–H), 7.08 (d, 1H,
N–CH), 5.48 (d, 1H, CH–Cl); MS: m/z 317 (M?), 319
(M? ? 2); Anal. Calcd for C15H12ClN3O3: C, 56.70; H,
3.81; N, 11.16; Found: C, 56.59; H, 3.67; N, 11.21.
N-[3-Chloro-2-(4-hydroxy-3-methoxy-phenyl)-4-
oxoazetidin-1-yl]isonicotinamide (2g)
Yield: 70%; m.p.: 211–213°C; IR (KBr, cm-1): 3405
(NH), 3029 (CH), 1651 (C=O), 685 (C–Cl); 1H NMR
(CDCl3), d (ppm): 12.13 (bs, 1H, CONH), 10.23(s, 1H,
OH), 8.05 (d, 1H, N–CH), 7.76–8.18 (m, 4H, pyridine),
7.24–7.57 (m, 3H, Ar–H), 5.73 (d, 1H, CH–Cl), 3.73 (s,
3H, OCH3); MS: m/z 347 (M?), 349 (M? ? 2); Anal.
Calcd for C16H14ClN3O4: C, 55.26; H, 4.06; N, 12.08;
Found: C, 55.03; H, 3.89; N, 12.18.
N-[3-Chloro-2-(2-methoxy-phenyl)-4-oxoazetidin-
1yl]isonicotinamide (2c)
Yield 70%; m.p.: 160–162°C; IR (KBr, cm-1): 3425 (NH),
3023 (CH), 1670 (C=O), 687 (C–Cl); 1H NMR (CDCl3), d
(ppm): 11.91 (bs, 1H, CONH), 7.75–8.79 (m, 4H, pyri-
dine), 7.3 (d, 1H, N–CH), 6.54–6.95 (m,4H, Ar–H), 5.47
(d, 1H, CH–Cl), 3.67 (s, 3H, OCH3); MS: m/z 331 (M?)
333 (M? ? 2); Anal. Calcd for C16H14ClN3O3: C, 57.93;
H, 4.25; N, 12.67; Found: C, 57.76; H, 4.13; N, 12.81.
N-[3-Chloro-2-(4-nitrophenyl)-4-oxoazetidin-1-
yl]isonicotinamide (2h)
Yield: 80%; m.p.: 192–194°C; IR (KBr, cm-1): 3415
(NH), 3011 (CH), 1661 (C=O), 672 (C–Cl); 1H NMR
(CDCl3), d (ppm): 11.97 (bs, 1H, CONH), 8.11 (d, 1H,
N–CH), 7.76–7.98 (m, 4H, pyridine), 7.14–7.58 (m, 4H,
Ar–H), 5.62 (d, 1H, CH–Cl); MS: m/z 346 (M?) 348
(M? ? 2); Anal. Calcd for C15H11ClN4O4: C, 51.96; H,
3.20; N, 16.16; Found: C, 51.75; H, 3.04; N, 16.01.
N-[3-Chloro-2-(4-dimethylamino-phenyl)-4-oxoazetidin-1-
yl]isonicotinamide (2d)
Yield: 70%; m.p.: 230–232°C; IR (KBr, cm-1): 3460
(NH), 3052 (CH), 1655 (C=O), 671 (C–Cl); 1H NMR
(CDCl3), d (ppm): 11.63 (bs, 1H, CONH), 8.31 (d, 1H,
N–CH), 7.77–8.29 (m, 4H, pyridine), 6.54–6.95 (m, 4H,
Ar–H), 5.43 (d, 1H, CH–Cl), 2.74 (s, 6H, 2CH3); MS: m/z
344 (M?), 346 (M? ? 2); Anal. Calcd for C17H17ClN4O2:
C, 59.22; H, 4.97; N, 16.25; Found: C, 59.03; H, 4.76; N,
16.11.
N-[3-Chloro-2-(2-nitrophenyl)-4-oxoazetidin-1-
yl]isonicotinamide (2i)
Yield: 74%; m.p.: 170–172°C; IR (KBr, cm-1): 3434
(NH), 2978 (CH), 1660 (C=O), 668 (C–Cl); 1H NMR
(CDCl3), d (ppm): 10.95 (bs, 1H, CONH), 8.12 (d, 1H,
N–CH), 7.75–7.87 (m, 4H, pyridine), 7.17–7.53 (m, 4H,
Ar–H), 5.49 (d, 1H, CH–Cl); MS: m/z 346 (M?) 348
(M? ? 2); Anal. Calcd for C15H11ClN4O4: C, 51.96; H,
3.20; N, 16.16; Found: C, 51.79; H, 3.14; N, 16.23.
N-[3-Chloro-2-(4-methyl-phenyl)-4-oxoazetidin-1-
yl]isonicotinamide (2e)
Yield: 60%; m.p.: 140–142°C; IR (KBr, cm-1): 3387
(NH), 3012 (CH), 1684 (C=O), 676 (C–Cl); 1H NMR
(CDCl3), d (ppm): 11.86 (bs, 1H, CONH), 8.42 (d, 1H,
N–CH), 7.89–8.39 (m, 4H, pyridine), 7.54–7.95 (m, 4H,
Ar–H), 5.49 (d, 1H, CH–Cl), 2.54 (s, 3H, CH3); MS: m/z
315 (M?), 317 (M? ? 2); Anal. Calcd for C16H14ClN3O2:
C, 60.86; H, 4.47; N, 13.31; Found: C, 60.67; H, 4.29; N,
13.17.
N-[3-Chloro-2-(4-chlorophenyl)-4-oxoazetidin-1-
yl]isonicotinamide (2j)
Yield: 72%; m.p.: 270–272°C; IR (KBr, cm-1): 3398
(NH), 3017 (CH), 1679 (C=O), 681 (C–Cl); 1H NMR
(CDCl3), d (ppm): 11.67 (bs, 1H, CONH), 8.17 (d, 1H,
N–CH), 7.78–8.01 (m, 4H, pyridine), 7.34–7.79 (m, 4H,
Ar–H), 5.47 (d, 1H, CH–Cl); MS: m/z 335 (M?) 337
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(M? ? 2); Anal. Calcd for C15H11Cl2N3O2: C, 53.59; H,
induced 1 h after administration of the standard drug or the
test compounds by i.p. injection of PTZ (30, 100, and
300 mg/kg) dissolved in saline to a volume of 0.1 ml/10 g
body weight. The time needed for the development of
unequivocal sustained clonic seizer activity involving the
limbs (isolated myoclonic jerks or other preconvulsive
chewing behavior were not counted) was carefully noted.
Animals which did not meet this criteria were considered
protected.
3.30; N, 12.50; Found: C, 53.47; H, 3.19; N, 12.39.
N-[3-Chloro-2-(2-chlorophenyl)-4-oxoazetidin-1-
yl]isonicotinamide (2k)
Yield: 85%; m.p.: 205–207°C; IR (KBr, cm-1): 3356
(NH), 3027 (CH), 1656 (C=O), 676 (C–Cl); 1H NMR
(CDCl3), d (ppm): 10.54 (bs, 1H, CONH), 8.03 (d, 1H,
N–CH), 7.67–7.98 (m, 4H, pyridine), 7.32–7.76 (m, 4H,
Ar–H), 5.43 (d, 1H, CH–Cl); MS: m/z 335 (M?) 337
(M? ? 2); Anal. Calcd for C15H11Cl2N3O2: C, 53.59; H,
3.30; N, 12.50; Found: C, 53.48; H, 3.14; N, 12.36.
Minimal motor impairment (neurotoxicity)
The undesirable effects (toxicity) were studied by moni-
tored the animals for overt sign of impaired neurological or
muscular function. In mice, rotorod procedure was used,
which rotate at a speed of 6 rpm. The dose at which ani-
mals fell off this rotating rod three times during a 1 min
period was considered.
N-(3-Chloro-2-oxo-4-phenyl-azetidin-1-yl)-
isonicotinamide (2l)
Yield: 70%; m.p.: 131–133°C; IR (KBr, cm-1): 3402
(NH), 3023 (CH), 1686 (C=O), 661 (C–Cl); 1H NMR
(CDCl3), d (ppm): 12.08 (bs, 1H, CONH), 8.21 (d, 1H,
N–CH), 7.68–8.11 (m, 4H, pyridine), 7.44–7.98 (m, 5H,
Ar–H), 5.74 (d, 1H, CH–Cl); MS: m/z 301 (M?) 303
(M? ? 2); Anal. Calcd for C15H12ClN3O2: C, 59.71; H,
4.01; N, 13.93; Found: C, 59.63; H, 4.14; N, 13.49.
CNS depression study
The forced swim method (Porsolt’s swim pool test) is
followed to study CNS depression (Porsolt et al., 1978).
Mice are placed in a chamber (diameter 45 cm, height:
20 cm) containing water up to a height of 15 cm at
25 2°C. Two swim sessions are conducted, an initial
15 min pre-test, followed by a 5 min test session 24 h later.
The animals are administered an i.p. injection (30 mg/kg)
of the test compounds 30 min before the test session. The
period of immobility (passive floating without struggling,
making only those movements which are necessary to keep
its head above the surface of water) during the 5 min test
period are measured.
Pharmacology
All the compounds were screened for anticonvulsant activity
adopting the anticonvulsant screening program (ASP)
including maximal electroshock test (MES), the subcutaneous
pentylene tetrazole (scPTZ), and evaluation of neurotoxicity
(TOX) (Krall et al., 1978; Porter et al., 1984; Kupferberg,
1989). The mice weighing 18–25.5 g of either sex were used,
and the number of animals used was six in each group. PEG-
400 was used for dissolving the test compounds in MES,
ScPTZ, and Minimal Motor Impairment Test. The compounds
were administered intraperitoneally (0.1 ml/10 g) to mice, at
doses of 30, 100, and 300 mg/kg body weight.
Acknowledgments The authors are thankful to University Grants
Commission (UGC), New Delhi, India for financial support. Authors
are also thankful to Mrs. Shukat shah, in-charge animal house Jamia
Hamdard, New Delhi for providing animals for pharmacological
studies.
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