Synthesis and pharmacological activities of some novel 5-chloro-N-(4-(1,5- (disubstituted)-4,5-dihydro-1H-pyrazol-3-yl)phenyl)-2-methoxybenzamide derivatives

Article abstract of DOI:10.1007/s00044-013-0807-x

A series of substituted pyrazole derivatives were prepared from N1-[4-(cinnamoyl) phenyl]-5-chloro-2-methoxybenzamides 2a-c, which were prepared from N-(4-acetylphenyl)-5-chloro-2-methoxybenzamide as starting material. Treating of compound 2a-c with methylhydrazine or phenylhydrazine afforded the corresponding N-substituted pyrazoline derivatives 3a-c and 4a-c, respectively. The acryloyl derivatives 2a-c were reacted with hydrazine hydrate in dioxane afforded a pyrazoline 5a-c, which was acetylated with acetyl chloride in dioxane to yield the N-acetyl analogue 6a-c. In addition, pyrazoline 5c was reacted with morpholine in the presence of paraformaldehyde to give the corresponding N-substituted pyrazoline derivative 7. The structure assignments of the new compounds are based on chemical and spectroscopic evidence. The pharmacological screening showed that many of these compounds have less toxicity and good anti-inflammatory activities. Springer Science+Business Media 2013.

Full text of DOI:10.1007/s00044-013-0807-x

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2014) 23:2113–2121
DOI 10.1007/s00044-013-0807-x
ORIGINAL RESEARCH
Synthesis and pharmacological activities of some novel 5-chloro-
N-(4-(1,5-(disubstituted)-4,5-dihydro-1H-pyrazol-3-yl)phenyl)-2-
methoxybenzamide derivatives
•
Mohamed M. Abdulla Abd El-Galil E. Amr
•
•
Mohamed A. Al-Omar Azza A. Hussain
•
Ahmed F. A. Shalaby
Received: 6 May 2013 / Accepted: 24 September 2013 / Published online: 6 October 2013
ꢀ Springer Science+Business Media New York 2013
Abstract A series of substituted pyrazole derivatives
were prepared from N1-[4-(cinnamoyl) phenyl]-5-chloro-
2-methoxybenzamides 2a–c, which were prepared from
N-(4-acetylphenyl)-5-chloro-2-methoxybenzamide as start-
ing material. Treating of compound 2a–c with meth-
ylhydrazine or phenylhydrazine afforded the corresponding
N-substituted pyrazoline derivatives 3a–c and 4a–c,
respectively. The acryloyl derivatives 2a–c were reacted
with hydrazine hydrate in dioxane afforded a pyrazoline
5a–c, which was acetylated with acetyl chloride in dioxane
to yield the N-acetyl analogue 6a–c. In addition, pyrazoline
5c was reacted with morpholine in the presence of para-
formaldehyde to give the corresponding N-substituted pyr-
azoline derivative 7. The structure assignments of the new
compounds are based on chemical and spectroscopic evi-
dence. The pharmacological screening showed that many of
these compounds have less toxicity and good anti-inflam-
matory activities.
Introduction
The pyrazoline and other related heterocyclic derivatives
exhibited a range of biological activities, such as analgesic,
antipyretic, and antirheumatic activities (Hukki et al., 1968
and Jung et al., 2005). Also, pyrazolines are reported as
antibacterial (Suvarna and Gandhi, 2008 and Fahmy et al.,
1987), antifungal (Mittra and Rao, 1977), antimicrobial
(Shah et al., 1996), antiviral (Husain and Shukla, 1986),
anti-arthritis (Rangari et al., 1990), analgesic and anti-
inflammatory (Nugent et al., 1993 and Amir and Kumar,
2005) agents. In a previous work, we found that certain
substituted pyrazoline derivatives showed anticancer,
androgenic, anabolic, and anti-arrhythmic activities (Abou-
Ghalia and Amr, 2004 and Shalaby et al., 2007). Recently,
the pharmacological activities of many compounds con-
taining azole rings have been reported (Said et al., 2009;
Ghozlan et al., 2009, 2011). In view of these observations
and in continuation of our previous work in heterocyclic
chemistry, we synthesized some new N1-{4-[1-substituted-
5-(substituted phenyl)-4,5-dihydro-1H-3-pyrazolyl]phenyl-
5-chloro-2-methoxy-benzamide derivatives and tested their
anti-inflammatory activities.
Keywords 5-Chloroanisic acid ꢀ Aldehydes ꢀ
N-substituted pyrazoline ꢀ Anti-inflammatory activities
M. M. Abdulla
Research Unit, Saco Pharm. Co., 6th October City 11632, Egypt
Materials and methods
A. E.-G. E. Amr (&) ꢀ M. A. Al-Omar
Pharmaceutical Chemistry Department, College of Pharmacy,
King Saud University, Riyadh 11451, Saudi Arabia
e-mail: aeamr1963@yahoo.com
Chemistry
Melting points are uncorrected and determined with elec-
trothermal capillary apparatus and were uncorrected. Ele-
mental analyses were performed in the Microanalytical
Unit, Faculty of Science, Ain Shams University using
Perkin Elmer CHN 2400 (one Run), Egypt and were found
within 0.4 % of the theoretical values. The IR spectra
A. E.-G. E. Amr
Applied Organic Chemistry Department, National Research
Center, Dokki, Cairo, Egypt
A. A. Hussain ꢀ A. F. A. Shalaby
Chemistry Department, Faculty of Science, Cairo University,
Gizza, Egypt
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5-Chloro-2-methoxy-N-(4-((E)-3-(4-nitrophenyl)acryloyl)
phenyl)benzamide 2c Yield 87 %, m.p. 268–270 ꢁC; IR
(KBr, cm-1) m: 3542 (NH), 1665 (CO, enone), 1668 (amide
were recorded in (KBr) on a Shimadzu CVT-04 spectro-
photometer. The 1H and 13C NMR spectra were determined
on Varian Gemini 270 MHz using CDCl3 or DMSO-d6 as
solvent and using TMS as an internal standard. The mass
spectra were performed using a Varian MAT CH-5 spec-
trometer (70 eV). All reactions were followed by TLC
(silica gel, aluminum sheets 60F254, Merck).
1
I), 1618 (amide II); H NMR (CDCl3) d ppm: 3.47 (s, 3H,
OCH3), 6.91 (d, 1H, arylidene-H), 7.23–7.58 (m, 11H, Ar–
H), 7.97 (d, 1H, arylidene-H), 10.70 (s, 1H, NH
exchangeable with D2O); 13C NMR (CDCl3): 57.10
(OCH3), 164.98 (CONH), 188.96 (C=O), 129.10, 155.20
(2C, CH=HC), 115.22 (C-3), 117.40 (C-1), 124.18 (C-5),
127.90 (C-6), 133.79 (C-4), 159.50 (C-2), 129.10 (C-20,
C-60), 130.00 (C-30, C-50), 134.60 (C-40), 136.70 (C-10),
128.70 (C-300, C-500), 139.90 (C-200, C-600), 142.70 (C-100),
148.90 (C-400); MS (EI, 70 eV): m/z (%): 436 [M?]. Ele-
mental analysis for C23H17ClN2O5 (436.84): Calcd. C, 63.
24; H, 3.92; Cl, 8.12; N, 6.41. Found: C, 63.16; H, 3.85; Cl,
8.08; N, 6.36.
Synthesis of N1-[4-(substituted acryloyl)phenyl]-5-
chloro-2-methoxybenzamide 2a–c
A mixture of acetyl derivative 1 (1 mmol), and aromatic
aldehydes, namely, 4-methoxy-, 2-nitro-, or 4-nitrobenz-
aldehyde (1 mmol) in absolute ethanol (50 mL) in the
presence of piperidine (0.5 mL) was refluxed for 30 min.
The reaction mixture was left overnight at room tempera-
ture, the obtained solid was filtered off, washed with die-
thyl ether, dried and crystallized from ethanol to give the
corresponding acryloyl derivatives 2a–c, respectively.
5-Chloro-N-(4-(5-(substituted phenyl)-4,5-dihydro-1-
substituted-1H-pyrazol-3-yl)phenyl)-2-methoxybenzamide
3a–c and 4a–c
5-Chloro-2-methoxy-N-(4-((E)-3-(4-methoxyphenyl)acry-
loyl)phenyl)benzamide 2a Yield 91 %, m.p. 287–289 ꢁC;
IR (KBr, cm-1) m: 3532 (NH), 1658 (CO, enone), 1669
(amide I), 1624 (amide II); 1H NMR (CDCl3) d ppm: 3.56,
3.82 (2s, 6H, 2OCH3), 6.90 (d, 1H, arylidene-H), 7.22–7.80
(m, 12H, Ar–H ? 1H arylidene), 11.65 (s, 1H, NH
exchangeable with D2O); 13C NMR (CDCl3): 55.46, 56.78
(2OCH3), 164.98 (CONH), 187.95 (C=O), 128.15, 155.01
(2C, CH=CH), 114.18 (C-3), 117.52 (C-1), 126.05 (C-5),
128.24 (C-6), 133.32 (C-4), 159.60 (C-2), 127.05 (C-20,
C-60), 130.10 (C-30, C-50), 133.72 (C-40), 137.76 (C-10),
113.42 (C-300, C-500), 128.52 (C-200, C600), 136.02 (C-100),
149.90 (C-400); MS (EI, 70 eV): m/z (%): 421 [M?]. Ele-
mental analysis for C24H20ClNO4 (421.87): Calcd. C, 68.
33; H, 4.78; Cl, 8.40; N, 3.32. Found: C, 68.28; H, 4.72; Cl,
8.35; N, 3.26.
A mixture of arylidene derivatives 2a–c (1 mmol) and
methylhydrazine or phenylhydrazine (4 mmol) in absolute
ethanol (25 mL) was refluxed for 5 h. The reaction mixture
was poured onto ice, the obtained solid was collected by
filtration, washed with water, dried, and crystallized from
methanol to give the corresponding N-substituted pyrazole
derivatives 3a–c and 4a–c, respectively.
5-Chloro-N-(4-(4,5-dihydro-5-(4-methoxyphenyl)-1-methyl-
1H-pyrazol-3-yl)phenyl)-2-methoxybenzamide 3a Yield
58 %, m.p. 273–275 ꢁC; IR (KBr, cm-1) m: 3565 (NH),
1
1668 (amide I), 1648 (C=N), 1624 (amide II); H NMR
(CDCl3) d ppm: 2.57 (s, 3H, N–CH3), 3.42, 3.70 (2s, 6H,
2OCH3), 4.02 (d, 2H, pyraz-H-4), 6.91 (m, 1H, pyraz-H-5),
7.13–7.86 (m, 11H, Ar–H), 11.10 (s, 1H, CONH,
exchangeable with D2O); 13C NMR (CDCl3): 36.60
(N–CH3), 55.20, 56.19 (2OCH3), 164.92 (CONH), 43.20
(C-4000), 67.69 (C-5000), 139.70 (C-3000), 115.24 (C-3), 117.10
(C-1), 127.90 (C-5), 128.80 (C-6), 133.70 (C-4), 158.10
(C-2), 128.40 (C-20, C-60), 131.09 (C-30, C-50), 135.10
(C-40), 139.10 (C-10), 118.90 (C-300, C-500), 120.14 (C-200,
C-600), 129.59 (C-100), 155.10 (C-4); MS (EI, 70 eV): m/z
(%): 449 [M?]. Elemental analysis for C25H24ClN3O3
(449.92): Calcd. C, 66.74; H, 5.38; Cl, 7.88; N, 9.34.
Found: C, 66.68; H, 5.32; Cl, 7.80; N, 9.26.
5-Chloro-2-methoxy-N-(4-((E)-3-(2-nitrophenyl)acryloyl)
phenyl)benzamide 2b Yield 85 %, m.p. 230–232 ꢁC; IR
(KBr, cm-1) m: 3548 (NH), 1662 (CO, enone), 1670 (amide
1
I), 1620 (amide II); H NMR (CDCl3) d ppm: 3.52 (s, 3H,
OCH3), 6.86 (d, 1H, arylidene-H), 7.18–7.68 (m, 11H, Ar–
H), 7.95 (d, 1H, arylidene-H), 11.05 (s, 1H, NH
exchangeable with D2O); 13C NMR (CDCl3): 56.58
(OCH3), 164.92 (CONH), 189.08 (C=O), 128.85, 154.98
(2C, CH=CH), 115.25 (C-3), 117.32 (C-1), 124.22 (C-5),
127.92 (C-6), 133.82 (C-4), 159.42 (C-2), 129.28 (C-20,
C-60), 130.10 (C-30, C-50), 134.64 (C-40), 136.55 (C-10),
128.68 (C-300), 129.46 (C-600), 130.05 (C-400), 139.85
(C-100), 142.05 (C-500), 148.76 (C-200); MS (EI, 70 eV):
m/z (%): 436 [M?]. Elemental analysis for C23H17ClN2O5
(436.84): Calcd. C, 63.24; H, 3.92; Cl, 8.12; N, 6.41.
Found: C, 63.18; H, 3.88; Cl, 8.05; N, 6.38.
5-Chloro-N-(4-(4,5-dihydro-1-methyl-5-(2-nitrophenyl)-
1H-pyrazol-3-yl)phenyl)-2-methoxybenzamide 3b Yield
69 %, m.p. 251–253 ꢁC; IR (KBr, cm-1) m: 3491 (NH),
1
1678 (amide I), 1665 (C=N), 1625 (amide II); H NMR
(CDCl3) d ppm: 2.58 (s, 3H, N–CH3), 3.51 (s, 3H, OCH3),
3.88 (d, 2H, pyraz-H-4), 6.95 (m, 1H, pyraz-H-5), 7.28–8.
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Med Chem Res (2014) 23:2113–2121
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09 (m, 11H, Ar–H), 10.80 (s, 1H, CONH, exchangeable
with D2O); 13C NMR (CDCl3): 36.62 (N–CH3), 57.12
(OCH3), 164.78 (CONH), 43.14 (C-4000), 66.88 (C-5000),
139.15 (C-3000), 115.70 (C-3), 117.22 (C-1), 127.02 (C-5),
128.90 (C-6), 133.42 (C-4), 157.62 (C-2), 128.15 (C-20,
C-60), 129.70 (C-30, C-50), 134.72 (C-40), 138.24 (C-10),
119.12 (C-300), 120.50 (C-600), 126.08 (C-400), 131.58
(C-100), 131.95 (C-500), 154.16 (C-100); MS (EI, 70 eV):
m/z (%): 465 [M?]. Elemental analysis for C24H21ClN4O4
(464.90): Calcd. C, 62.00; H, 4.55; Cl, 7.63; N, 12.05.
Found: C, 61.96; H, 4.50; Cl, 7.57; N, 12.00.
3.64 (s, 3H, OCH3), 4.05 (d, 2H, pyraz-H-4), 6.92 (m, 1H,
pyraz-H-5), 7.04–7.98 (m, 16H, Ar–H), 10.93 (s, 1H,
CONH, exchangeable with D2O); 13C NMR (CDCl3): 56.
36 (OCH3), 164.66 (CONH), 43.08 (C-4000), 66.92 (C-5000),
143.24 (C-3000), 116.05 (C-3), 118.12 (C-1), 128.55 (C-5),
128.66 (C-6), 134.32 (C-4), 157.95 (C-2), 129.10 (C-20,
C-60), 129.84 (C-30, C-50), 135.62 (C-40), 139.15 (C-10),
119.18 (C-300), 122.05 (C-600), 128.76 (C-400), 131.68
(C-100), 133.98 (C-500), 154.06 (C-100), 119.47 (C-20000, C-60000),
120.65 (C-40000), 128.85 (C-30000, C-50000), 141.95 (C-10000); MS
(EI, 70 eV): m/z (%): 527 [M?]. Elemental analysis for
C29H23ClN4O4 (526.97): Calcd. C, 66.10; H, 4.40; Cl, 6.73;
N, 10.63. Found: C, 66.00; H, 4.36; Cl, 6.67; N, 10.59.
5-Chloro-N-(4-(4,5-dihydro-1-methyl-5-(4-nitrophenyl)-
1H-pyrazol-3-yl)phenyl)-2-methoxybenzamide 3c Yield
71 %, m.p. 233–235 ꢁC; IR (KBr, cm-1) m: 3552 (NH),
5-Chloro-N-(4-(4,5-dihydro-1-phenyl-5-(4-nitrophenyl)-
1H-pyrazol-3-yl)phenyl)-2-methoxybenzamide 4c Yield
65 %, m.p. 218–220 ꢁC; IR (KBr, cm-1) m: 3542 (NH),
1668 (amide I), 1626 (amide II); 1H NMR (CDCl3) d ppm:
3.64 (s, 3H, OCH3), 3.99 (d, 2H, pyraz-H-4), 6.78 (m, 1H,
pyraz-H-5), 7.10–8.05 (m, 16H, Ar–H), 10.56 (s, 1H,
CONH, exchangeable with D2O); 13C NMR (CDCl3): 57.
45 (OCH3), 165.04 (CONH), 43.55 (C-4000), 67.65 (C-5000),
143.24 (C-3000), 114.78 (C-3), 117.19 (C-1), 128.36 (C-5),
128.56 (C-6), 135.48 (C-4), 158.16 (C-2), 127.92 (C-20,
C-60), 128.76 (C-30, C-50), 133.66 (C-40), 141.18 (C-10),
128.70 (C-300, C-500), 131.00 (C-200, C-600), 134.15 (C-100),
154.98 (C-400), 121.02 (C-20000, C-60000), 123.88 (C-40000), 129.
05 (C-30000, C-50000), 148.52 (C-10000); MS (EI, 70 eV): m/z (%
): 527 [M?]. Elemental analysis for C29H23ClN4O4 (526.
97): Calcd. C, 66.10; H, 4.40; Cl, 6.73; N, 10.63. Found: C,
66.02; H, 4.35; Cl, 6.66; N, 10.58.
1
1665 (amide I), 1645 (C=N), 1624 (amide II); H NMR
(CDCl3) d ppm: 2.61 (s, 3H, N–CH3), 3.54 (s, 3H, OCH3),
3.98 (d, 2H, pyraz-H-4), 6.81 (m, 1H, pyraz-H-5), 7.18–8.
10 (m, 11H, Ar–H), 10.51 (s, 1H, CONH, exchangeable
with D2O); 13C NMR (CDCl3): 36.58 (N–CH3), 57.30
(OCH3), 164.88 (CONH), 43.25 (C-4000), 67.71 (C-5000),
147.90 (C-3000), 116.90 (C-3), 118.80 (C-1), 127.90 (C-5),
128.30 (C-6), 133.70 (C-4), 158.10 (C-2), 123.93 (C-20,
C-60), 129.44 (C-30, C-50), 135.40 (C-40), 139.10 (C-10),
120.22 (C-300, C-500), 131.07 (C-200, C-600), 141.10 (C-100),
155.10 (C-400); MS (EI, 70 eV): m/z (%): 464 [M?]. Ele-
mental analysis for C24H21ClN4O4 (464.90): Calcd. C, 62.
00; H, 4.55; Cl, 7.63; N, 12.05. Found: C, 61.95; H, 4.50;
Cl, 7.58; N, 12.00.
5-Chloro-N-(4-(4,5-dihydro-5-(4-methoxyphenyl)-1-phe-
nyl-1H-pyrazol-3-yl)phenyl)-2-methoxybenzamide 4a
Yield 62 %, m.p. 218–220 ꢁC; IR (KBr, cm-1) m: 3534
(NH), 1664 (amide I), 1622 (amide II); 1H NMR (CDCl3) d
ppm: 3.47, 3.78 (2 s, 6H, 2OCH3), 4.15 (d, 2H, pyraz-H-4),
6.92 (m, 1H, pyraz-H-5), 7.10–7.98 (m, 16H, Ar–H), 10.96
(s, 1H, CONH, exchangeable with D2O); 13C NMR
(CDCl3): 55.31, 56.16 (2OCH3), 164.66 (CONH), 44.17
(C-4000), 66.94 (C-5000), 143.56 (C-3000), 114.68 (C-3), 117.18
(C-1), 127.92 (C-5), 128.88 (C-6), 134.12 (C-4), 159.41
(C-2), 128.96 (C-20, C-60), 129.65 (C-30, C-50), 136.02
(C-40), 139.84 (C-10), 128.55 (C-300, C-500), 131.11 C-200,
C-600), 134.50 (C-100), 155.60 (C-400), 119.09 (C-20000, C-60000),
120.22 (C-40000), 129.05 (C-30000, C-50000), 142.60 (C-10000); MS
(EI, 70 eV): m/z (%): 512 [M?]. Elemental analysis for
C30H26ClN3O3 (512.00): Calcd. C, 70.38; H, 5.12; Cl, 6.92;
N, 8.21. Found: C, 70.32; H, 5.06; Cl, 6.88; N, 8.16.
5-Chloro-N-(4-(5-(substituted phenyl)-4,5-dihydro-1H-
pyrazol-3-yl)phenyl)-2-methoxybenzamide 5a–c
A mixture of arylidene derivatives 2a–c (1 mmol) and
hydrazine hydrate (0.4 g, 8 mmol) in dioxane (25 mL) was
refluxed for 2 h. The reaction mixture was evaporated
under reduced pressure, the residue triturated with petro-
leum ether (40–60 ꢁC), the obtained solid was filtered off,
washed with n-hexane, dried, and crystallized from meth-
anol to give the corresponding substituted pyrazolone
derivatives 5a–c, respectively.
5-Chloro-N-(4-(4,5-dihydro-5-(4-methoxyphenyl)-1H-pyr-
azol-3-yl)phenyl)-2-methoxybenzamide 5a Yield 58 %,
m.p. 298–300 ꢁC; IR (KBr, cm-1) m: 3564 (NH), 1668
(amide I), 1646 (C=N), 1621 (amide II); 1H NMR (CDCl3)
d ppm: 3.45, 3.67 (2s, 6H, 2OCH3), 4.10 (d, 2H, pyraz-H-
4), 6.88 (m, 1H, pyraz-H-5), 7.02–7.92 (m, 11H, Ar–H),
9.14, 10.96 (2 s, 2H, 2NH, exchangeable with D2O); 13C
NMR (CDCl3): 56.54, 57.10 (2OCH3), 164.86 (CONH),
5-Chloro-N-(4-(4,5-dihydro-1-phenyl-5-(2-nitrophenyl)-
1H-pyrazol-3-yl)phenyl)-2-methoxybenzamide 4b Yield
69 %, m.p. 211–213 ꢁC; IR (KBr, cm-1) m: 3513 (NH),
1673 (amide I), 1623 (amide II); 1H NMR (CDCl3) d ppm:
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44.18 (C-4000), 68.74 C-5000), 139.78 (C-3000), 115.36 (C-3),
117.16 (C-1), 128.14 (C-5), 128.82 (C-6), 134.00 (C-4),
158.15 (C-2), 128.42 (C-20, C-60), 129.62 (C-30, C-50), 131.
16 (C-40), 139.12 (C-10), 118.87 (C-300, C-500), 120.24
(C-200, C-600), 135.16 (C-100), 155.12 (C-400); MS (EI,
70 eV): m/z (%): 435 [M?]. Elemental analysis for
C24H22ClN3O3 (435.90): Calcd. C, 66.13; H, 5.09; Cl, 8.13;
N, 9.64. Found: C, 66.07; H, 5.02; Cl, 8.08; N, 9.60.
extract solution was washed with diluted sodium carbonate
then water, dried over calcium chloride anhydrous. The
dichloromethane was evaporated under reduced pressure to
dryness, the residue was crystallized from methanol to give
N-acetylpyrazole derivatives 6a–c, respectively.
N-(4-(1-Acetyl-4,5-dihydro-5-(4-methoxyphenyl)-1H-pyra-
zol-3-yl)phenyl)-5-chloro-2-methoxybenzamide 6a Yield
80 %, m.p. 249–251 ꢁC; IR (KBr, cm-1) m: 3535 (NH),
1
1676 (amide I), 1652 (C=N), 1626 (amide II); H NMR
5-Chloro-N-(4-(4,5-dihydro-5-(2-nitrophenyl)-1H-pyrazol-
3-yl)phenyl)-2-methoxybenzamide 5b Yield 64 %, m.p.
168–170 ꢁC; IR (KBr, cm-1) m: 3510 (NH), 1674 (amide
I), 1668 (C=N), 1622 (amide II); 1H NMR (CDCl3) d ppm:
3.47 (s, 3H, OCH3), 3.85 (d, 2H, pyraz-H-4), 6.78 (m, 1H,
pyraz-H-5), 7.31–8.92 (m, 11H, Ar–H), 9.55, 10.86 (2 s,
2H, 2NH, exchangeable with D2O); 13C NMR (CDCl3): 56.
82 (OCH3), 164.86 (CONH), 43.24 (C-4000), 66.65 (C-5000),
139.35 (C-3000), 115.74 (C-3), 117.18 (C-1), 125.82 (C-5),
127.12 (C-6), 133.55 (C-4), 157.68 (C-2), 129.72 (C-20,
C-60), 131.63 (C-30, C-50), 134.67 (C-40), 138.36 (C-10),
119.40 (C-300), 120.58 (C-600), 128.24 (C-400), 128.92
(C-100), 132.34 (C-500), 154.24 (C-200); MS (EI, 70 eV):
m/z (%): 450 [M?]. Elemental analysis for C23H19ClN4O4
(450.87): Calcd. C, 61.27; H, 4.25; Cl, 7.86; N, 12.43.
Found: C, 61.19; H, 4.18; Cl, 7.79; N, 12.36.
(CDCl3) d ppm: 2.38 (s, 3H, N–CH3), 3.41, 3.64 (2 s, 6H,
2OCH3), 3.86 (d, 2H, pyraz-H-4), 6.78 (m, 1H, pyraz-H-5),
6.98–7.73 (m, 11H, Ar–H), 10.70 (s, 1H, CONH,
exchangeable with D2O); 13C NMR (CDCl3): 24.10 (CH3),
55.22, 56.38 (2OCH3), 164.90 (COCH3), 165.92 (CONH),
40.95 (C-4000), 62.69 (C-5000), 142.12 (C-3000), 115.22 (C-3),
116.34 (C-1), 127.12 (C-5), 128.30 (C-6), 134.00 (C-4),
159.57 (C-2), 129.92 (C-20, C-60), 131.08 (C-30, C-50), 133.
40 (C-40), 139.16 (C-10), 118.96 (C-300, C-500), 120.90
(C-200, C-600), 147.18 (C-100), 158.57 (C-400); MS (EI,
70 eV): m/z (%): 478 [M?]. Elemental analysis for
C26H24ClN3O4 (477.94): Calcd. C, 65.34; H, 5.06; Cl, 7.42;
N, 8.79. Found: C, 65.30; H, 5.00; Cl, 7.35; N, 8.72.
N-(4-(1-Acetyl-4,5-dihydro-5-(2-nitrophenyl)-1H-pyrazol-
3-yl)phenyl)-5-chloro-2-methoxybenzamide
6b Yield
5-Chloro-N-(4-(4,5-dihydro-5-(4-nitrophenyl)-1H-pyrazol-
3-yl)phenyl)-2-methoxybenzamide 5c Yield 76 %, m.p.
201–203 ꢁC; IR (KBr, cm-1) m: 3488 (NH), 1664 (amide
I), 1646 (C=N), 1623 (amide II); 1H NMR (CDCl3) d ppm:
3.42 (s, 3H, OCH3), 3.88 (d, 2H, pyraz-H-4), 6.93 (m, 1H,
pyraz-H-5), 7.25–7.95 (m, 11H, Ar–H), 9.34, 10.85 (2 s,
2H, 2NH, exchangeable with D2O); 13C NMR (CDCl3): 56.
19 (OCH3), 165.10 (CONH), 44.03 (C-4000), 65.76 (C-5000),
141.11 (C-3000), 117.06 (C-3), 118.73 (C-1), 124.32 (C-5),
127.93 (C-6), 133.55 (C-4), 158.15 (C-2), 129.56 (C-20,
C-60), 130.94 (C-30, C-50), 134.88 (C-40), 139.12 (C-10),
121.02 (C-300, C-500), 128.32(C-200, C-600), 147.96 (C-100),
156.10 (C-400); MS (EI, 70 eV): m/z (%): 450 [M?]. Ele-
mental analysis for C23H19ClN4O4 (450.87): Calcd. C, 61.
27; H, 4.25; Cl, 7.86; N, 12.43. Found: C, 61.21; H, 4.20;
Cl, 7.80; N, 12.37.
82 %, m.p. 255–257 ꢁC; IR (KBr, cm-1) m: 3538 (NH),
1678 (CO), 1670 (amide I), 1622 (amide II); H NMR
1
(CDCl3) d ppm: 2.38 (s, 3H, CH3), 3.54 (s, 3H, OCH3), 4.
00 (d, 2H, pyraz-H-4), 6.85 (m, 1H, pyraz-H-5), 7.22–7.98
(m, 11H, Ar–H), 10.82 (s, 1H, CONH, exchangeable with
D2O); 13C NMR (CDCl3): 24.30 (CH3), 56.48 (OCH3),
164.52 (COCH3), 165.12 (CONH), 43.00 (C-4000), 66.42
(C-5000), 139.77 (C-3000), 114.92 (C-3), 116.70 (C-1), 126.32
(C-5), 127.62 (C-6), 133.46 (C-4), 157.81 (C-2), 129.58
(C-200, C-60), 131.25 (C-30, C-50), 135.08 (C-40), 139.44
(C-1 ), 118.76 (C-300), 119.70 (C-600), 127.91 (C-400), 129.05
(C-100), 132.42 (C-500), 154.00 (C-200); MS (EI, 70 eV):
m/z (%): 493 [M?]. Elemental analysis for C25H21ClN4O5
(492.91): Calcd. C, 60.92; H, 4.29; Cl, 7.19; N, 11.37.
Found: C, 60.85; H, 4.24; Cl, 7.14; N, 11.33.
N-(4-(1-Acetyl-4,5-dihydro-5-(4-nitrophenyl)-1H-pyrazol-
Synthesis of N-(4-(1-acetyl-5-(substituted phenyl)-4,5-
dihydro-1H-pyrazol-3-yl)phenyl)-5-chloro-2-
methoxybenzamide 6a–c
3-yl)phenyl)-5-chloro-2-methoxybenzamide
6c Yield
86 %, m.p. 268–270 ꢁC; IR (KBr, cm-1) m: 3542 (NH),
1678 (CO), 1666 (amide I), 1618 (amide II); H NMR
1
(CDCl3) d ppm: 2.45 (s, 3H, COCH3), 3.36 (s, 3H, OCH3),
3.84 (d, 2H, pyraz-H-4), 6.90 (m, 1H, pyraz-H-5), 7.35–8.
05 (m, 11H, Ar–H), 10.48 (s, 1H, CONH, exchangeable
with D2O); 13C NMR (CDCl3): 24.28 (CH3), 56.48
(OCH3), 165.24 (CONH), 164.76 (COCH3), 42.42 (C-4000),
A mixture of pyrazoline derivatives 5a–c (1 mmol) and
acetyl chloride (0.25 mL) in dioxane (25 mL) was left for
5 h at room temperature. The reaction mixture was poured
onto ice-water, extracted with dichloromethane. The
123

Med Chem Res (2014) 23:2113–2121
2117
60.44 (C-5000), 141.51 (C-3000), 115.32 (C-3), 118.54 (C-1),
127.16 (C-5), 127.92 (C-6), 133.41 (C-4), 156.72 (C-2),
128.65 (C-20, C-60), 131.33 (C-30, C-50), 133.44 (C-40), 139.
36 (C-10), 121.42 (C-300, C-500), 127.65 (C-200, C-600), 131.37
(C-100), 155.48 (C-400); MS (EI, 70 eV): m/z (%): 493 [M?].
Elemental analysis for C25H21ClN4O5 (492.91): Calcd. C,
60.92; H, 4.29; Cl, 7.19; N, 11.37. Found: C, 60.86; H,
4.23; Cl, 7.15; N, 11.32.
was evaporated under reduced pressure, the residue was
triturated with diethyl ether, and the obtained solid was
filtered off, dried and crystallized from methanol to give
the corresponding N-substituted pyrazolophenyl derivative
7. Yield 56 %, m.p. 118–120 ꢁC; IR (KBr, cm-1) m: 3531
(NH), 1665 (amide I), 1624 (amide II); 1H NMR (CDCl3) d
ppm: 2.41–2.48 (m, 4H, morpholine-H), 3.52 (s, 3H,
OCH3), 3.56–3.58 (m, 4H, morpholine-H), 3.81 (s, 2H,
CH2), 3.88 (d, 2H, pyraz-H-4), 6.81-6.86 (m, 1H, pyraz-H-
5), 7.43–8.17 (m, 11H, Ar–H), 10.70 (s, 1H, CONH,
exchangeable with D2O); 13C NMR (CDCl3): 49.88
(C-20000), 68.86 (C-30000), 56.27 (OCH3), 67.61 (N–CH2),
165.10 (CONH), 43.48 (C-4000), 62.10 (C-5000), 142.16
(C-3000), 115.10 (C-3), 117.10 (C-1), 126.10 (C-5), 128.82
(C-6), 133.39 (C-4), 156.10 (C-2), 127.56 (C-20, C-60),
131.01 (C-30, C-50), 135.10 (C-40), 139.45 (C-10), 120.42
Synthesis of 5-chloro-N-(4-(4,5-dihydro-1-
(morpholinomethyl)-5-(4-nitrophenyl)-1H-pyrazol-3-
yl)phenyl)-2-methoxybenzamide 7
A mixture of pyrazoline derivative 5c (2 mmol), morpho-
line (2 mmol) and paraformaldehyde (0.2 g) in absolute
ethanol (25 mL) was refluxed for 1 h. The reaction mixture
O
O
O
Mixed anhydride
Method
Cl
CH3
OH
+
O
CH3
Cl
H2N
OMe
N
H
1
OMe
CHO
O
3`
6`
2``
1``
3``
2`
1`
O
4`
5`
6
3
X
X
5
Cl
1
4``
6``
N
2a-c
H
5``
2
4
OMe
CH3NHNH2
EtOH
PhNHNH2
EtOH
2```
N
1```
N
CH3
5````
6````
1```
3`
2``
4````
3````
5```
1``
3``
2`
1`
O
3```
2```
N
4`
5`
4```
6
X
N
1```
`
2````
2``
5
Cl
1
4``
6``
3`
5```
N
1``
3``
6`
3a-c
H
5``
2`
1`
2
O
3```
4`
5`
4```
4
6
3
X
OMe
5
Cl
1
4``
3
6``
N
6`
4a-c
H
5``
2
4
2-4, a, X = 4-OMe;
b, X = 2-NO2;
OMe
c, X = 4-NO2
Scheme 1 Synthetic pathways for compounds 2–4
123

2118
Med Chem Res (2014) 23:2113–2121
(C-300, C-500), 129.10 (C-200, C-600), 148.10 (C-100), 155.60
(C-400); MS (EI, 70 eV): m/z (%): 550 [M?]. Elemental ana-
lysis for C28H28ClN5O5 (550.01): Calcd. C, 61.14; H, 5.13; Cl,
6.45; N, 12.73. Found: C, 61.10; H, 5.08; Cl, 6.40; N, 12.66.
Anti-inflammatory activity
Carrageenan-induced Edema (rats paw test)
Groups of adult male albino rats (150–180 g), each of eight
animals, were orally dosed with tested compounds at a dose
level of 25–50 mg/kg 1 h before carrageenan challenge.
All animals were obtained from the Animal House Colony,
Research Institute of Ophthalmology, Giza, Egypt. Foot
paw edema was induced by subplantar injection of
0.05 cm3 of a 1 % suspension of carrageenan in saline into
the plantar tissue of one hind paw. An equal volume of
saline was injected to the other hand paw and served as
control. 4 h after drug administration the animals were
Pharmacological screening
Determination of acute toxicity (LD50)
The LD50 was determined by using rats. They were injected
with different increasing doses of the synthesized com-
pounds. The dose that killed 50 % of the animal was cal-
culated according to Austen and Brocklehurst 1961.
O
1```
2```
N
N
CH3
2``
3`
NH2NH2
3```
4```
4`
1``
2`
1`
3``
2a-c
O
5```
AcOH/Ac2O
6
X
4``
Cl
5
1
2
5`
6``
N
6`
H
5``
NH2NH2
Dioxane
6a-c
4
OMe
a, X = 4-OMe;
b, X = 2-NO2;
c, X = 4-NO2
3
1```
2```
H
N
N
3`
2``
3```
4```
4`
1``
2`
1`
3``
O
5```
6
X
CH3COCl
Dioxane
Cl
5
1
2
5`
6``
4``
N
6`
H
5``
4
OMe
5a-c
3
a, X = 4-OMe;
b, X = 2-NO2;
c, X = 4-NO2
3````
2````
1```
2```
N
O
5c
N
N
morpholine
3`
6`
2``
3```
4`
1``
2`
1`
3``
4``
O
5```
Paraformaldehyde
4```
6
Cl
5
1
5`
6``
N
NO2
H
5``
7
4
2
OMe
3
Scheme 2 Synthetic pathways for compounds 5–7
123

Med Chem Res (2014) 23:2113–2121
2119
decapitated, blood was collected, and the paws were rap-
idly excised. The average weight of edema was examined
for the treated as well as the control group and the per-
centage inhibition of weight of edema was also evaluated.
Prednisolone (5 mg/kg) was employed as standard refer-
ence against which the tested compounds were compared.
two arylidene protons. The disappearance of the enone
absorption band and the presence of the (CONH) absorp-
tion bands at their normal expected values in the IR spectra
of both compounds 3a–c and 4a–c constituted a good
evidence for their structural formulae.
Cyclocondensation of 2a–c with hydrazine hydrate in
refluxing dioxane afforded the pyrazoline derivatives 5a–c,
which were treated with acetyl chloride in dioxane to yield
the corresponding N-acetyl pyrazoline derivatives 6a–c,
respectively. The latter compounds were also prepared
directly from 2a–c by the action of hydrazine hydrate in the
presence of an acetic acid/acetic anhydride mixture.
Finally, the reaction of compound 5c with morpholine in
the presence of paraformaldehyde afforded the corre-
sponding N-substituted methylpyrazoline derivatives
(Mannish bases) 7 (Scheme 2).
Estimation of plasma prostaglandin E2 (PGE2)
Heparinized blood samples were collected from rats
(n = 8), plasma was separated by centrifugation at
12,0009g for 2 min at 40 ꢁC, immediately frozen, and
stored at 20 ꢁC until use. The design correlate EIA pros-
taglandin E2 (PGE2) kit (Aldrich, Steinheim, Germany) is
a competitive immune assay for the quantitative determi-
nation of PGE2 in biological fluids. The kit uses a mono-
clonal antibody to PGE2 to bind, in a competitive manner,
the PGE2 in the sample after a simultaneous incubation at
room temperature. The excess reagents were washed away
and the substrate was added, after a short incubation time
the enzyme reaction was stopped, and the yellow color
generated was read on a microplate reader DYNATech,
MR 5000 at 405 nm (Dynatech Industries Inc., McLean,
VA, USA). The intensity of the bound yellow color is
inversely proportional to the concentration of PGE2 in
either standard or samples.
Pharmacological screening
Anti-inflammatory potency
Initially the acute toxicity of the compounds was assayed
determining their LD50. Interestingly, all the synthesized
compounds and starting materials were less toxic than the
reference drug (Table 1). Then the newly synthesized
compounds were pharmacologically screened for their anti-
inflammatory potency using male albino rats. The resulting
data for anti-inflammatory evaluation are summarized in
Tables 2 and 3.
Results and discussion
Synthesis
In the continuation of our previous work (Abdulla et al.,
2013), a series of substituted pyrazoline derivatives were
synthesized according to our previously reported procedure
(Abdulla M et al., 2013). Also, the acetyl derivative 1 was
prepared from 5-chloroanisic acid and p-aminoacetophe-
none according to the mixed anhydride technique (Amr
et al., 2006), followed by treating with aromatic aldehydes
in ethanolic piperidine to give N1-[4-(substituted acry-
Table 1 Acute toxicity LD50 of the synthesized compounds
Comp. no.
LD50 mg/kg
2a
2b
2c
3a
3b
3c
4a
4b
4c
3e
3f
2234.77
2398.69
1829.57
2387.64
2345.63
2543.74
2387.36
2387.27
2383.38
2506.65
1544.53
1409.43
5678.47
2345.56
2387.28
1595.55
loyl)phenyl]-5-chloro-2-methoxybenzamide
derivatives
2a–c, respectively. The latter compounds were treated with
methylhydrazine or phenylhydrazine in refluxing absolute
ethanol to yield the corresponding 5-chloro-N-(4-(4,5-
dihydro-5-(substituted
phenyl)-1-methyl-1H-pyrazol-3-
yl)phenyl)-2-methoxybenzamides 3a–c and 5-chloro-N-(4-
(4,5-dihydro-5-(4-methoxyphenyl)-1-phenyl-1H-pyrazol-
3-yl)phenyl)-2-methoxybenzamides 4a–c, respectively
(Scheme 1). The structure of derivatives 2a–c revealed the
appearance of the conjugated enone of the newly formed
arylidene in IR spectra and also 1H NMR revealed the
disappearance of the acetyl protons, and the appearance of
3g
4e
4f
4g
5f
123

2120
Med Chem Res (2014) 23:2113–2121
Purpose and rational
Table 3 Anti-inflammatory potency of the synthesized compounds
(Inhibition of plasma PGE2)
For the determination of the antiphlogistic potency of the
synthesized compounds, two standard tests were realized at
25 and 50 mg/kg body weight of the rats, namely the
protection against carrageenan-induced edema according to
Winter et al., 1962 and the inhibition of plasma PGE2. The
latter is known as a good confirming indicator for the
carrageenan-induced rat paw edema (Herrmann et al.,
1990). From the resulting data, regarding the protection
against carrageenan-induced edema, all the tested com-
pounds showed potent anti-inflammatory activities. The
Compound no.
Dose (mg kg-1)
Inhibition of plasma
PGE2 (%)
Prednisloneꢂ
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
78.10c
92.10c
68.10a
79.18b
69.10a
80.40b
69.60c
81.75c
83.80a
91.25b
71.35c
83.20c
82.26c
90.24c
73.32b
84.35a
75.32c
85.28c
70.55b
83.00a
72.29a
84.46b
76.32c
86.32a
79.44a
88.39a
77.24c
87.24c
80.14b
90.10b
2a
2b
3a
3b
3c
4a
4b
4c
5a
5b
5c
6a
6b
7
Table 2 Anti-inflammatory potency of the synthesized compounds
(protection against CarrageenanR induced edema)
Compound no.
Dose (mg kg-1)
Protection against
CarrageenanR
induced edema (%)
Predensiloneꢂ
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
80.40a
92.10b
79.00c
93.10a
81.80c
85.85c
88.10c
93.15b
96.45c
99.50c
93.00a
97.40b
94.82b
98.00b
80.18b
88.40c
90.85c
94.10b
82.55a
89.00b
88.30c
90.89a
91.25b
95.30b
86.00c
90.20c
92.16b
96.15b
94.13c
97.90a
2a
2b
3a
3b
3c
4a
4b
4c
5a
5b
5c
6a
6b
7
a
P \ 0.05
b
P \ 0.01
c
P \ 0.001
order of activity in descending manner is 3b, 4a, 7, 3c, 6b,
5c, 4c, 3a, 5b, 6a, 5a, 4b, and 2b.
Structural activity relationship (SAR)
•
•
The increase of the lipophilicity leads to increase of the
anti-inflammatory activity.
The 2-nitro group provides higher activities than the
4-nitro group and the latter provides higher activity
than the 4-methoxy one.
a
P \ 0.05
b
P \ 0.01
•
N-phenyl group in pyrazole ring increases the activity
more than the unsubstituted derivatives.
c
P \ 0.001
123

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2121
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•
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•
•
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123