chapter 3 synthesis, characterization and...
TRANSCRIPT
CHAPTER 3
SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL STUDIES
OF SOME NEW PYRAZOLE DERIVATIVES
94
3.1 Introduction
Pyrazoles belongs to the family of azoles, i.e. five-membered rings containing
only nitrogen and carbon atoms (Fig. 3.1), ranging from pyrrole to pentazole. According
to Albert’s classification, they are π-excessive N-Heteroaromatic derivatives, and
according to Kauffmann’s arenology principle1 they are analogues of amines.
NH
N 2
34
5
Fig. 3.1: Structure of Pyrazole
Pyrazoles, which are N-unsubstituted at position-1 exhibit annular tautomerism.
The two tautomeric forms (a) and (b) are identical entities and are in rapid equilibrium
with each other (Fig. 3.2). The two nitrogen atoms are thus indistinguishable.
NH
N
N
NH
a b
Fig. 3.2: Resonance structure of pyrazole
Pyrazole is less reactive towards electrophilic than pyrrole. As a neutral molecule
it reacts as readily as benzene and, as an anion, as readily as phenol (diazo coupling,
nitrosation, etc). Pyrazole cations, formed in strong acidic media, show a pronounced
deactivation for nitration, sulfonation, Friedel-Crafts reactions, etc. For the same reason,
quaternary pyrazolium salts normally do not react with electrophiles. Electrophilic attack
on pyrazoles takes place at position C-4 in accordance with localization energies and π-
electron densities.1
95
Attack in other positions is extremely rare. This fact, added to the deactivating
effect of the substituent introduced in the 4th
position, explains why further electrophilic
substitution is generally never observed. Very little is known about the nucleophilic
attack on an unsubstituted carbon atom of pyrazoles and their aromatic derivatives.
Amongst the various heterocycles, pyrazole classes of compounds play an important role
in medicinal chemistry. Pyrazole and its derivatives, a class of well known nitrogen
containing heterocyclic compounds, occupy an important position in medicinal and
pesticide chemistry with having a wide range of bioactivities.
3.1.1 Synthetic approaches and pharmacological activity of pyrazoles
Pyrazole and its derivatives represent one of the most active classes of compounds
possessing a wide spectrum of biological activities. During the past years, considerable
evidence has accumulated to demonstrate the efficacy of pyrazole derivatives including
antitumor,2
antibacterial and antifungal,3 antiviaral,
4 analgesic,
5 anti-proliferative,
6
antileukemic,7,8
antidiabetic,9
and antidepressant.
10
Murineddu, et al (2006)11
synthesized a series of dihydroindeno substituted
pyrazole carboxamide derivatives and evaluated for its cannabinoid receptor affinity
(Scheme-3.1). Among the compound, (193) with cyclohexyl carboxamide showed single
digit nanomolar affinity for cannabinoid CB2 receptors.
96
R1
R2O
R1
R2O
O
O
OR1
R2
NN
O
O
Cl
Cl
R1
R2NN
O
OH
Cl
Cl
R1
R2
NN
O
NH
Cl
Cl
R3
189 190 191
192193
NaH, EtOH,
(COOEt)2 2,4-Cl2C6H3NHNH2.HCl,
CH3COOH
KOH, EtOH/H2O R3-NH2
Where R1 = CH3, R2= H, R3 =Cl F CF3
Scheme-3.1: 1-(2, 4-Dichlorophenyl)-6-methyl-N-piperidin-1-yl-1, 4-dihydroindeno [1,
2-c] pyrazole-3-carboxamide derivatives
Heller et al, (2006)12
stabilized a rapid one pot synthesis of Pyrazoles (197) from
1,3-diketones (196), were synthesized directly from ketones and acid chlorides by treating
with hydrazines (Scheme-3.2). This method proved as extremely fast, general and
chemoselective method for the synthesis of demanding pyrazole containing drugs.
R1
OLi
R2
+R3 Cl
O
R1
O
R3
O
R2
NN
R4
R1
R2
R3R4-NHNH2
194 195 196
197
Scheme-3.2: One pot Synthesis of pyrazoles from 1, 3-diketones by acid chlorides and
ketones
97
Bernardino and co-workers (2006)13
synthesized different 1-(4-X-phenyl)-N′-[(4-
Y phenyl) methylene]-1H-pyrazole-4-carbohydrazides (198) and investigated their
leishmanicidal in vitro activities and cytotoxic effects were investigated (Fig. 3.3). It was
found that, among all the 1H-pyrazole-4-carbohydrazides derivatives examined, the most
active compounds were those with R1= Br, R1 = NO2 (27) and R1 = NO2, R2 = Cl
derivatives.
198
NN
O
NH
N
R1
R2
Fig. 3.3: 1-(4-phenyl)-N′-[(4-Y-phenyl) methylene]-1H-pyrazole-4-carbohydrazides
Chovatia et al, (2007)14
synthesized a series of 1-acetyl-3, 5-diphenyl-4,5-
dihydro-(1H)-pyrazole derivatives (199) and these compounds were tested in vitro for
their antitubercular and antimicrobial activities (Fig. 3.4).
NN
N
N
RS
O
H3C
199
Where R = Ph, 4-Cl-C6H4, 4-Br-C6H4, 4-Me-C6H4, 4-OMe-C6H4, 4-SMe-C6H4
4-OH-C6H4, 2-OHC6H4, 4-NO2C6H4, 3-NO3C6H4
Fig. 3.4: Synthesis of 1-acetyl-3, 5-diphenyl-4, 5-dihydro-(1H)-pyrazole derivatives
98
A series of new nitro substituted triaryl pyrazole derivatives (200) was
synthesized by Naoum et al, (2007)15
and evaluated their binding affinity towards
estrogen receptor (Fig. 3.5).
N N
R
HO
NO2
OH
X
200
Where X= OH, R= n-Pr, Et, Me
Fig. 3.5: Novel nitro-substituted triaryl Pyrazole derivatives
Sahu et al, (2008)17
synthesized a series of pyrazoline derivatives (201) and
studied its anti-inflammatory and antimicrobial activities. The results of this investigation
revealed that the observed increase in analgesic, anti-inflammatory and antimicrobial
activities are attributed to the presence of 4- NO2, 2-OH and 4-Cl in phenyl ring at 5-
position of pyrazoline ring of synthesized compounds (Fig. 3.6).
HN
N NH
R
HO
201
Where R= Ph, 2-Furyl, 4-NO2-C6H4, 4-OMe-C6H4, 2-OH-C6H4, 4-Cl-C6H4
Fig. 3.6: Synthesis of Pyrazole containing 4-hydrozy phenyl derivatives
Catagnolo et al, (2008)17
synthesized evaluated SAR study of new Pyrazole
analogues as inhibitors of Mycobacterium tuberculosis. One of their synthesized
99
compound (206) with R1=CH3 and with R= Br showed high activity against MTB
(Scheme-3.3).
R1
O
OEt
OR-NHNH2
NN
O
R
R1
NN
O
R
R1
NN
OH
R
R1NN
OH
R
R1O
Cl
EtOH
Reflux
PTSA
p-Cl-C6H4COCl
203204
205 206
202
Where R = Cl, H, F, Br, CH3, Isopropyl, R1 = CH3, CF3, Isopropyl, Ph, Bn, 4-F-Bn, 4-NO2Bn
Scheme-3.3: p-Chlorophenyl substitituted pyrazoles
Silvestri et al, (2008)18
synthesized 1-phenyl-5-(1H-pyrrol-1-yl)-pyrazole-3-
carboxamides (Fig. 3.7) (207). Compounds bearing 2,4-dichlorophenyl or 2,4-
difluorophenyl groups at position 1 and 2,5-dimethylpyrrole moiety at position 5 of the
pyrazole nucleus were generally more selective for hCB1.
N
NN
O
NH
R2
R1
R4
R3
207
Fig. 3.7: Substituted 1-Aryl-5-(1H-pyrrol-1-yl)-1H-pyrazole-3-carboxamides.
Synthesis of Schiff and Mannich bases containing pyrazole moiety was earlier
reported by Isloor et al, (2009).19
The newly synthesized compounds (208) were screened
100
for their antibacterial and antifungal activity (Fig. 3.8). Several of the compounds were
found to show evidence of significant antimicrobial activity.
208NNH
R1
N
N
NN
S
NR2
R3R4
Fig. 3.8: Mannich bases derived from pyrazole and 1,2,4-triazoles
Gerstenberger et al, (2009)20
recently achieved a simple one pot synthesis of N-
Arylpyrazoles (212) from different aryl halides, di-tert-butylazodicarboxylate and 1,3-
dicarbonyl compounds (Scheme-3.4).
X
+ Boc
N
N
Boc+ R1
O
R3
O
R2
NN
R2
R1
R3
R
R
One pot
25-75%
209210 211
212
Scheme-3.4: One pot synthesis of N-aryl pyrazoles from aryl halides
Synthetic approach for the some new pyrazolo [3,4-d] pyrimidine derivatives (213)
were evaluated by Ghorab and co-workers (2010).21
Newly synthesized compounds were
screened for their anticancer studies (Fig. 3.9). Among them some of the compounds
were found to be potent anticancer agents.
101
NN
Ph
N
N
O
O
N NH
S OO N
MeSSMe
213
Fig. 3.9: Synthesis of some new pyrazolo [3, 4-d] pyrimidine derivatives
A simple efficient catalyst free one pot synthesis of 1,4,5-trisubstituted pyrazole
derivatives (215) were prepared by Alinezhad et al, (2011)22
by condensation of β-
dicarbonyls and DMF-acetal and hydrazine derivatives (Scheme-3.5).
O
O O
Me
MeO
MeO
N
NN
Ph
O
O
MePhNHNH2
Trfiluoro ethanol215
214
Scheme-3.5: Catalyst-free one-pot synthesis of 1, 4, 5-trisubstituted pyrazoles in 2, 2, 2-
trifluoroethanol
It has found that Sharma et al, (2011)23
synthesized some 4-functionalized
pyrazole derivatives (Scheme-3.6) and studied its antimicrobial studies. Among the
synthesized compound (220) shows very good activity.
102
SO2NH2
NH2NH2HCl
CH3COONa
EtOH
SO2NH2
NHN
R
R CH3
O
POCl3
DMF, 60 oC
S
NN
OHC R
OO
NH2
S
NN
OHC R
OO
NCH
N
S
NN
HOOC R
OO
NH2
217 218
219 220
Pyridine
NaOH
216
KMnO4
Where R= Ph, 4-Me-Ph, 4OMe-Ph, 4-F-Ph, 4-Br-Ph, 4-No2-Ph, 2-Me-Thiophene
Scheme-3.6: 4-Functionalized-pyrazole derivatives
Manikannan et al, (2011)24
synthesized a set of different 2, 4-dinitro substituted
pyrazoles by the Vilsmeier reaction of 2, 4-dinitro phenyl hydrazones of phenacyl aryl
sulfides (Fig. 3.10 ) (221).
N
N
NO2
NO2
Ar2 S Ar1
221
Fig. 3.10: Synthesis of 1-(2, 4,-dinitrophenyl)-3-aryl-4-(arylsulfanyl)-1H-Pyrazole
103
A new substituted pyrazoles (226) were prepared from o-hydroxyacetophenone
and cinnamic acids by Priyadarsini et al, (2012).25
The synthesized compounds were
evaluated for antimicrobial activity (Scheme-3.7). Compound having chloro substitution
on the styryl ring was found to be more potent among the synthesized compounds.
OH
O
R1
HOOC
O
O
O
R1
OH
O O
R1
NN
R2
R1
HO
Pyridine/POCl3
+Pyridine/KOH
NaOH
224
225226
222 223
Where R1 = Cl, OMe
R2 = H, Ph
Scheme-3.7: Synthesis of of novel pyrazoles from hydroxyacetophenone
Mistry and his co workers (2012)26
synthesized microwave assisted quinoline
substituted pyrazole derivatives (228-230) (Scheme-3.8) and screening of their
antibacterial and antifungal activities. Among the synthesized compounds having halogen
substituent’s shows very good activity.
104
N
H3C
Cl
O
R
NCl
N NHR
NCl
N NR NH2
O
N
Cl
NN
R
NH2S
227
228
229
230
NH2NH2.H2O
NH2CONHNH2.HCl
NH2CSNHNH2.HCl
MW, 5 Min
Where R=H, 4-Br, 4-Cl, 4-CH3, 4-OMe, 4-OH, 2,4-di chloro, 4-NO2
Scheme-3.8: Conventional and microwave assisted synthesis of pyrazole derivatives
Zhibing Wu et al, (2012)27
recently synthesized N-(substituted pyridinyl)-1-
methyl (phenyl)-3-trifluoromethyl-1Hpyrazole- 4-carboxamide derivatives (Fig. 3.11)
and bioassayed in vitro against different kinds of phytopathogenic fungi. The results
showed that some of the synthesized N-(substituted pyridinyl)-1-methyl-3-
trifluoromethyl-1H-pyrazole-4-carboxamides exhibited moderate antifungal activities,
among which compounds (231, 232) displayed more than 50% inhibition activities
against G. zeae at 100 μg/mL, which was better than that of the commercial fungicides
carboxin and boscalid.
105
NN
F3C
O
NH
CH3
N
Br
NN
F3C
O
NH
CH3
N
F
F
F
232231
Fig . 3.11: N-(Substituted pyridinyl)-1-methyl (phenyl)-3-(trifluoromethyl)-1H-pyrazole-
4-carboxamide derivatives
Ming-Xia Song et al, (2013)28
synthesized and studied anti-bacterial activity of 5-
aryloxy pyrazole and rhodanine derivatives (233, 234) (Fig. 3.12). The majority of the
synthesized compounds showed good inhibitory activity against selected methicillin
resistant and quinolone-resistant Staphylococcus aureus (MRSA, QRSA) with minimum
inhibitory concentration (MIC) values in the range of 1–32 μg/mL.
NN O
S
N
O
S
CO2H
R
233
N NO
S
N
O
S
CO2H
R
234
Where R = 2,6-(Cl)2, 2,4-(Cl)2, 2-Cl, 2,4-(CH3)2, 3-CF3, 4-Br,
Fig. 3.12: Rhodanine-based 5-aryloxy pyrazoles
Khunt et al, (2012)29
synthesized N-phenyl-3-(4-fluorophenyl)-4-substituted
pyrazoles derivatives (Fig. 3.13) and tested for antimycobacterial activity in vitro
against Mycobacterium tuberculosis H37Rv strain using the BACTEC 460 radiometric
system. Among compound (235) having p-methoxy phenyl at 4th
position of pyrazole ring
shows most active at IC50 of 0.47 μM.
106
NN
F
HNN O
235
Fig. 3.13: N-Phenyl-3-(p-fluorophenyl)-4-[3-(p-anisyl)-pyrazoline-5-yl] pyrazole
Recently Pyrazole [3, 4-e] [1, 4] thiazepin-7-one-based derivaivtives (238) were
synthesized by Marinozzi and co-workers (2012).30
Synthesized compounds were
evaluated by a cell-based luciferase transactivation assay for their agonistic activity
against FXR. Most of them exhibited low micromolar range of potency and very high
efficacy (Scheme-3.9).
CHO
NN
NH2
NN
NH
S
O
R1 R2
+
R1
R2
2-mercaptopropanoic acid,
toulene, reflux
237 238236
Scheme-3.9 : Synthesis of 1H-pyrazole [3, 4-e] [1, 4] thiazepin-7-one
Review of literature indicated that pyrazole derivatives possess significant
biological activities. Prompted by the therapeutic importance, it was contemplated to
synthesize some new two series of 1, 5-disubstituted pyrazole esters and its carboxamide
derivatives. Antimicrobial activity of such heterocyclic compounds evaluated separately
for both the series was also discussed.
107
3.2. Results and discussion
3.2.1 Synthesis new Ethyl 1-(N-substituted)-5-phenyl-1H-pyrazole-4-carboxylate 241 (a-
n) and N-(Substituted)-5-phenyl-1-(quinolin-2-yl)-1H-pyrazole-4-carboxamide
derivatives 243 (a-h)
In the present synthesis a series of new 1H-Pyrazole ester derivatives 241(a-n)
were synthesized by condensing Ethyl-3-(dimethylamino)-2-[(phenyl)carbonyl]prop-2-
enoate (240) with different aromatic/aliphatic hydrazines as per the reported literature. 31
Compound (240) was synthesized by refluxing ethyl benzoyl acetate (239) with DMF-
acetal to afford Ethyl-3-(dimethylamino)-2-[(phenyl) carbonyl] prop-2-enoate (240) as
yellow liquid. Among these esters, (241h) were hydrolyzed by treating with NaOH.
Further this carboxylic acid derivative (242) was coupled with different
aromatic/aliphatic amines using 50% T3P in ethyl acetate (Propyl phosphonic anhydride)
as coupling reagent to afford different substituted 243 (a-h) pyrazole carboxamide
derivatives (Scheme-2). All the newly synthesized compounds were screened for their
antibacterial studies. These newly synthesized compounds were characterized by NMR,
mass spectral, IR spectral study and also by C, H, N analyses. All the newly synthesized
compounds were screened for their antibacterial studies. Molecular structure of
compounds (241a) and (241j) were also confirmed by single crystal X-ray analysis.32,33
The synthesized compounds from corresponding amines are mentioned in Table-3.1 and
Table-3.2
108
O
OEt
O
N
O
O
O
N,N-DMF-ACETAL
100 0C, 18 hr
R-NH-NH2
Abs Ethanol, 80 0C, 2hr239240
N N
N
OO
NN
N
OOH
NN
N
ONH
R2
LiOH/THF/H2OR2NH2/T3P/THF
241h242 243(a-h)
241 (a-n)
N N
R1
O
OO
RTRT
Scheme-3.10: Synthetic route for the title compounds 241(a-n) and 243(a-h)
Table 3.1: List of compounds synthesized from the scheme-3.10
Sl.No Hydrazines (R1) Product M.p (oC)
Yield
(%)
1
NHH2N
NN
O
O
241a
128-130 86.9
2
NH
OHO
H2N
OHO
NN
O
O
241b
105-106 77.7
109
3
NHH2N
OH
O
NN
O
O
OH
O 241
c
99-100 92
4
NH
FF
H2N
F
NN
O
O
F
F
F
241d
98-100 86
5
NH
H2N
NN
O
O
241e
129-130 78
6
NHH2N
F
NN
O
O
F 241f
149-150 79
110
7
NHH2N
Br
NN
O
O
Br
241g
80-82 68
8 N
H2N
NH
NN
O
O
N
241h
150-151 81
9
NHH2N
NN
O
O
241i
105-106 68
10
HN
NH2
N
N
O
O
241j
69-70 71
111
11 CH3-NHNH2
NN
O
O
241k
74-75 75
12
NHH2N
Cl
Cl
NN
O
O
Cl
Cl
241l
129-130 86
13
HN
NH2HN
NN
O
O
HN241m
69-72 83
14
HNNH2
NN
O
O
241n
89-90 87
112
Table 3.2: List of compounds synthesized from the scheme-3.10
Sl.No Amines (R2) Product M.p (oC) Yield (%)
1
NH
O
O
NN
N
N
O
243a
198-200 86
2
NH
HN
O
NN
N
N
HN
243b
178-180
82
3
NH
N
O
NN
N
N
N
243c
156-157
91
113
4
NH2
NN
O
HN
N
243d
201-203 93
5
NH2
NN
O
HN
N
243e
200-202 78
6
NH2
NN
O
HN
N
243f
220-222 95
7 NH
NN
O
N
N
243g
189-190 88
114
8 NH N
N
O
N
N
243h
177-179 83
Formation of the ethyl-1-(N-substituted)-5-phenyl-1H-pyrazole-4-carboxylate
derivatives were confirmed by recording their IR, 1H-NMR,
13C-NMR, mass spectra and
by single crystal X-ray analysis. IR spectrum of compound (241a) showed absorption at
3483 cm-1
and 2976 cm-1
, which is due to the aromatic stretching. Absorption band at
1594 cm-1
is due to C=N of Pyrazole ring, a band at 1509 cm-1
is due to C=C, absorptions
at 1220 cm-1
and at 1682 cm-1
are due to the C-O, C=O stretch of ester respectively.
The 1H-NMR of spectrum of (241a) showed a singlet at δ 8.19, which due to the
Pyrazole -CH, multiplet observed in the region of δ 7.40-7.34 is due to the six aromatic
protons, similarly another multiplet observed in the range of δ 7.30-7.21 is due to the four
protons of the aromatic ring. The mass spectrum of compound (241a) showed the
molecular ion peak at m/z 292, which is in agreement with the molecular formula
C18H16N2O2. Similarly the spectral values for all the compounds and C, H, N analyses are
given in the experimental part. Also the single crystal X-ray analysis of (241a) and (241j)
further confirmed the structure of the synthesized compounds. The structre of (241b) was
also confirmed unambiguously by NOE amd NOESY experiments. By irradiating pyrazole ring
H (singlet at δ 8.23), there is no enhancement occurred and it confirms the required isomer.
Similarly, for compound (243a), the absorption band at 3065, 2957, 2905 cm-1
due
to the aromatic stretching of phenyl ring. An absorption band at 1618 cm-1
is due to C=N
group, band at 1549 cm-1
is due to carbonyl group C=O of ester functional group. The 1H
115
NMR of (243a) showed singlet in the region of δ 8.03, which is due to the Pyrzole ring
proton. Similarly doublet in the region of δ 8.55-8.52, δ 7.87-7.85 and 7.45-7.43 with
coupling constant 8.76, 8.76 and 8.36 respectively is due to quinoline ring protons.
Similarly multiplet in the region of δ 7.39-7.34 and δ 7.33-7.25 is due to the phenyl ring
protons. Similarly multiplet in the region of 3.55-3.42 and 3.25-2.97 is due to the
morpholin ring protons. The mass spectrum of (243a) showed molecular ion peak at m/z
385.2, which is agreement with the molecular formula C23H20N4O2. Similarly the spectral
values for all the compounds and C, H, N analyses are given in the experimental part.
3.2.2 Synthesis of Ethyl 1-(N-substituted)-5-(4-Methoxy-phenyl)-1H-pyrazole-4-
carboxylate 202 (a-l) and N-(Substituted)-5-phenyl-1-[4-(propan-2-yl) phenyl]-1H-
pyrazole-4-carboxamide derivatives 248 (a-h).
In the present synthesis a series of new Pyrazole ester derivatives 246 (a-l) were
synthesized by condensing Ethyl-3-(dimethylamino)-2-[(4-methoxy phenyl) carbonyl]
prop-2-enoate (245) with different aromatic/aliphatic hydrazines. Among these esters,
(246d) was hydrolyzed by treating with base. Further this carboxylic acid derivative (247)
was coupled with different aromatic/aliphatic amines using 50% T3P in ethyl acetate
(Propyl phosphonic anhydride) as coupling reagent to afford different substituted 248 (a-
h) pyrazole carboxamide derivatives (Scheme-3.11). All the newly synthesized
compounds were screened for their antibacterial studies. These newly synthesized
compounds were characterized by NMR, mass spectral, IR spectral study and also by C,
H, N analyses. All the newly synthesized compounds were screened for their antibacterial
studies. Molecular structure of compound (246f) was also confirmed by single crystal X-
ray analysis.34
The synthesized compounds from corresponding amines are mentioned in
Table-3.3 and Table-3.4
116
N,N-DMF-ACETAL
100 0C, 18 hr
R-NH-NH2
Abs Ethanol, 80 0C, 2hr
LiOH/THF/H2O R2NH2/T3P/THF
O
O
O
O
O
O
O
O N N N
R1
O
OO
NN
O
O
O
NN
O
O
OH
NN
O
O
NH
R2
RT RT
244245
246 (a-l)
246d 247248(a-h)
Scheme-3.11: Synthetic route for the title compounds 246(a-l) and 248 (a-h).
Table 3.3: List of compounds synthesized from the scheme-3.11
Sl.No Hydrazines (R1) Product M.p (oC)
Yield
(%)
1
NHH2N
NN
O
O
O
246a
150-151 86
2
NH
OHO
H2N
O OH
NN
O
O
O
246b
155-156 84
117
3
NHH2N
OH
O
NN
O
O
O
OH
O
246c
190-192 80
4
NH2NH2
NN
O
O
O
246d
168-169 88
5
NH
F
H2N
NN
O
O
O
F
246e
180-182 81
6
NHH2N
NN
O
O
O
246f
100-101 65
118
7
NHH2N
NN
O
O
O
246g
123-124 81
8
NHH2N
NN
O
O
O
2
46h
199-201 64
9
HN
NH2
N
N
O
O
O
246i
128-130 68
10 NH
NH2N
NN
O
O
N
O
246j
201-203 79
119
11
NH
H2N
Br
NN
O
O
OBr
246k
128-129 89
12
HN
NH2HN
NN
O
O
NH
O
246l
89-90 65
Table 3.4: List of compounds synthesized from the Scheme-3.11
Sl.No Amines (R2) Product M.p (oC) Yield (%)
1
NH
HN
O
N
HN
NN
O
24
8a
326-327 86
120
2 NH
O
O
N
O
NN
O
248
b
342-343 82
3
NH
N
O
NN
O
N
N
248
c
326-328 91
4
NH2
NN
O
HN
O
248d
305-307 93
5
NH2
NN
O
HN
O
2
48e
298-300 95
121
6
NH2
O
HN
NN
O
248f
348-349 78
7 NH
NN
O
N
O
2
48g
289-291 88
8 NH
NN
O
N
O
2
48h
293-295 83
Formation of 1-(N-substituted)-5-(4-methoxy-phenyl)-1H-pyrazole 246(a-l)
derivatives was confirmed by recording their IR, 1H-NMR,
13C-NMR., elemental analysis
and mass spectral data. The IR spectrum of (246a) showed absorption band at 3102, 2991
cm-1
which is due to the aromatic stretching of phenyl ring. An absorption band at 1614
122
cm-1
is due to C=N group, band at 1705 cm-1
is due to carbonyl group C=O of ester
functional group. The 1H NMR of (246a) showed singlet in the region of δ 8.14, which is
due to the Pyrzole ring proton. Similarly multiplet the region of δ 7.38-7.33 and δ 7.22-
7.21 is due to the phenyl ring protons, the para pattern in the region of δ 7.20-7.18 and δ
6.90-6.88 with coupling constant 8.8 Hz and 9.6 Hz was due to the 4-methoxy phenyl
ring protons. Similarly singlet at δ 3.70 is for the three protons of methoxy group. The
quartet observed at the region of δ 4.14 and triplet observed at δ 1.30 is for the ethyl ester
group protons. The mass spectrum of (246a) showed molecular ion peak at m/z 324,
which is agreement with the molecular formula C19H18N2O3.
Similarly, for compound (248a), the absorption band at 2936, 2923, 2861 cm-1
due
to the aromatic stretching of phenyl ring. An absorption band at 1626 cm-1
is due to C=N
group, band at 1513 is due to carbonyl group C=O of ester functional group. The 1H
NMR of (248a) showed singlet in the region of δ 7.83, which is due to the Pyrzole ring
proton. Similarly multiplet the region of δ 7.17-7.14 and δ 7.10-7.07 (m, 2H) is due to the
4-isopropyl phenyl ring protons, the para pattern in the region of δ 7.26-7.24 and δ 6.94-
6.92 with coupling constant 8.48 Hz and 8.84 Hz was due to the 4-methoxy phenyl ring
protons. Similarly singlet at δ 3.74 is for the three protons of methoxy group and
multiplet observed in the aliphatic region of δ 3.4-3.32 and δ 3.32-3.30 is due to the
morpholin ring protons. Similarly, multiplet at δ 2.92-2.85 for one proton and doublet at δ
1.18 for six protons is due to the isopropyl group of phenyl ring. The mass spectrum of
(248a) showed molecular ion peak at m/z 406.2, which is agreement with the molecular
formula C24H27N3O3.
Similarly the spectral values for all the compounds and C, H, N analyses are given in the
experimental part. Also single crystal X-ray analysis of (248f) further confirmed the
structure of synthesized compounds.
123
All the Chemicals were procured from Aldrich Co. Reactions were monitored and
purity of the products was checked by TLC which was performed on MERCK 60F-254
silica gel plates. Melting points were determined on BUCHI Melting point B-545
instrument. The IR spectra (in KBr pellets) were recorded on NICOLET 6700FT-IR
spectrophotomter. 1H-NMR spectra were recorded on BRUKER (400 MHz) spectrometer
in DMSO-d6 solvent. Mass spectra were recorded on LC-MS-Agilent 1200 series with
MSD (Ion trap) using 0.1% aqueous TFA in acetonitrile system on C18-BDS column for
10 min duration. The elemental analysis was performed on THERMO Finningan FLASH
EA 1112 CHN analyzer. Column chromatography was performed on silica gel (60-120
mesh) supplied by Acme Chemical Co. (India) for compound purification.
3.3 Synthesis
3.3.1 General procedure
3.3.1.1 General method for the Preparation of Ethyl-3-(dimethylamino)-2-
[(Substitued) phenyl) carbonyl] prop-2-enoate (240 and 245)
A mixture of Ethylbenzoylacetate/Ethyl (4-methoxy benzoyl) acetate (195/200)
(10 g) and N, N dimethyl formamide dimethyl acetal (25 mL) was heated to reflux for 18
h. The excess of acetal was distilled off under reduced pressure to afford title compound
240/245 as pale yellow gummy liquid.
3.3.1.2 General procedure for preparation of different Ethyl 1-(N-substituted)-5-(4-
(substituted) phenyl)-1H-pyrazole-4-carboxylate derivatives 241 (a-n) and 246 (a-l)
To a solution of Ethyl-3-(dimethylamino)-2-[(Substituted) phenyl) carbonyl]
prop-2-enoate (240/245) (1.0 eq) in different series of aromatic/aliphatic hydrazines (1.1
eq) were refluxed with absolute ethanol (10 vol) for 2 h, excess of solvent was evaporated
under reduced pressure. The residue was washed with 1.5N HCl and the solid separated
was filtered and dried under vacuum. The solid obtained was purified by column
124
chromatography using silica gel 60-120 mesh size and petroleum ether: ethyl acetate as
eluent to afford different N-substituted-5-(4-substituted)-phenyl-1H-pyrazole-4-ethyl
carboxylate as white and pale yellow crystalline solid.
3.3.1.3 General procedure for the synthesis 5-[(4-substituted) phenyl]-1-
(substituted)-1H-pyrazole-4-carboxylic acid (242/247)
To a solution of Ethyl 1-(N-substituted)-5-[4-(substituted) phenyl]-1H-pyrazole-4-
carboxylate (241h/246d) (0.015 mol, 1.0 eq) in a mixture of THF (7 vol) and water (3vol)
was added Lithium hydroxide (0.029 mol, 2.0 eq) at RT. The reaction mixture was stirred
at RT for 6 h. The reaction mixture was concentrated under high vacuum, the residue was
acidified with 1.5 N HCl, the solid separated out was filtered and dried under suction to
affor the tilte compound (242/247) (88%) as white solid.
3.3.1.4 General procedure for the synthesis of N-(Substituted)-5-methyl-1-
(substitued)-1H-pyrazole-4-carboxamide derivatives 243 (a-h) and 248 (a-h)
To a solution of 5-[(4-substituted) phenyl]-1-(substituted)-1H-pyrazole-4-
carboxylic acid (198/203) (1.58 mmol, 1.0 eq) in dry THF (10 vol) was added triethyl
amine (3.17mmol, 2.0 eq) followed by 50 % T3P in ethyl acetate (2.3 mmol, 1.5 eq) and
different aromatic/aliphatic amines (1.58 mmol, 1.0 eq) at RT under nitrogen atmosphere.
After the completion, the reaction mixture was concentrated under high vacuum; the
residue was basified with 10% NaHCO3 solution and extracted with ethyl acetate (100
mL). The organic layer was washed with brine, dried over Na2SO4 and concentrated under
high vacuum. The solid obtained was purified by column chromatography using silica gel
60-120 mesh size and petroleum ether: ethyl acetate as eluent to afford title compounds
243 (a-h) and 248 (a-h) as off white solid.
125
3.4. Characterization
3.4.1. Experimental data
3.4.1.1 Ethyl 1,5-diphenyl-1H-pyrazole-4-carboxylate (241a)
(2.0 g, 86.9%); IR (KBr) cm–1
: 3483, 2976 (Ar-H), C=N (1594-stretch of Pyrazole ring),
C=C (1509), C-O (1220), C=O (1682 stretch of ester); MS: m/z = 293.1 (M+);
1H-NMR
(DMSO-d6): δ 8.19 (s, 1H, pyrazole -CH), 7.40-7.34 ( m, 6H, Ar-H), 7.30-7.21 (m, 4H,
Ar-H), 4.29 (q, 2H), 1.30 (t, 3H, J = 7.12 Hz). Anal. Calcd. (Found) for C18H16N2O2: C,
73.95 (74.00); H, 5.52 (5.48); N, 9.58 (9.40).
3.4.1.2 4-[4-(Ethoxycarbonyl)-5-phenyl-1H-pyrazol-1-yl] benzoic acid (241b)
(2.1 g, 77.7 %); IR (KBr) cm–1
: 2990, 2880 (Ar-H), C=N (1600-stretch of Pyrazole ring),
C=C (1509), C-O (1230), C=O (1700-stretch of ester); MS: m/z = 337.3 (M
+);
1H-NMR
(DMSO-d6): δ 13.13 (bs, 1H, -COOH), 8.23 (s, 1H, pyrazole -CH), 7.88-7.86 (d, 2H, J =
8.56 Hz, Ar-H), 7.43-7.28 (m, 7H, Ar-H), 4.13-4.08 (q, 2H), 1.12-1.08 (t, 3H, J = 7.12
Hz). 13
CNMR (DMSO-d6) 166.3, 161.8, 145.3, 142.2, 142.1, 130.4, 130.1, 129.9, 129.2,
128.2, 128.02, 125.3, 113.8, 59.7, 13.9. Anal. Calcd.(Found) for C19H16N2O4 : C, 67.85
(67.66); H, 4.79 (4.88); N, 8.33 (8.56).
3.4.1.3 4-[3-(ethoxycarbonyl)-5-phenyl-1H-pyrazol-1-yl] benzoic acid (241c)
(2.5 g, 92%); IR (KBr) cm–1
: 3453, 2996 (Ar-H), C=N (1634-stretch of Pyrazole ring),
C=C (1560), C-O (1300), C=O (1642-stretch of ester); MS: m/z = 337.3 (M
+);
1H-NMR
(DMSO-d6) : δ 13.17 (bs, 1H, -COOH), 8.21 (s, 1H, pyrazole -CH), 7.88-7.86 (d, 1H, J =
7.44 Hz, Ar-H), 7.78 (s, 1H, Ar-H), 7.47-7.29 (m, 7H, Ar-H), 4.13-4.07 (q, 2H), 1.15-
1.08 (t, 3H, J = 7.04 Hz). Anal. Calcd.(Found) for C19H16N2O4 : C, 67.85 (67.80); H, 4.79
(4.82); N, 8.33 (8.42).
3.4.1.4 Ethyl 5-phenyl-1-[4-(trifluoromethyl) phenyl]-1H-pyrazole-4-carboxylate (241d)
126
(2.5g, 86%); IR (KBr) cm–1
: 3553, 2896 (Ar-H), C=N (1658-strecth of Pyrazole ring),
C=C (1567), C-O (1412), C=O (1650-stretch of ester); MS: m/z = 361.3 (M
+);
1H-NMR
(DMSO-d6): δ 8.25 (s, 1H, pyrazole -CH), 7.75-7.73 (d, 2H, J = 8.48 Hz, Ar-H), 7.44-
7.39 (m, 5H, Ar-H), 7.36-7.31 (t, 2H, J = 11.6 Hz, Ar-H), 4.13-4.08 (q, 2H), 1.12-1.08 (t,
3H, J = 7.08 Hz). Anal. Calcd. (Found) for C19H15F3N2O2 : C, 63.33 (63.33); H, 4.20
(4.24); N, 7.77 (7.72).
3.4.1.5 Ethyl 1-(4-tert-butylphenyl)-5-phenyl-1H-pyrazole-4-carboxylate: (241e)
(2.2g, 78%); IR (KBr) cm–1
: 3560, 2885 (Ar-H), C=N (1670-stretch of Pyrazole ring),
C=C (1585), C-O (1415), C=O (1660-stretch of ester); MS: m/z = 349.4 (M
+);
1H NMR
(DMSO-d6): δ 8.15 (s, 1H, pyrazole -CH), 7.38-7.32 (m, 5H, Ar-H), 7.29-7.28 (d, 2H, J =
7.64 Hz, Ar-H), 7.14-7.12 (d, 2H, J = 8.52 Hz, Ar-H), 4.11-4.06 (q, 2H), 1.22(s, 9H, tert-
buty) 1.10-1.07 (t, 3H, J = 7.08 Hz). Anal. Calcd.(Found) for C22H24N2O2: C, 75.83
(75.63); H, 6.94 (7.00); N, 8.04 (7.95).
3.4.1.6 Ethyl 1-(4-fluorophenyl)-5-phenyl-1H-pyrazole-4-carboxylate (241f)
(1.8, 79%); IR (KBr) cm –1
: 3570, 2865 (Ar-H), C=N (1690-stretch of Pyrazole ring),
C=C (1575), C-O (1445), C=O (1670-stretch of ester); MS: m/z = 311.3 (M
+);
1H-NMR
(DMSO-d6): δ 8.17 (s, 1H, pyrazole -CH), 7.38-7.32 (m, 3H, Ar-H), 7.29-7.27 (m, 4H,
Ar-H), 7.27-7.18 (m, 2H, Ar-H), 4.12-4.07 (q, 2H), 1.11-1.08 (t, 3H, J = 7.08 Hz). Anal.
Calcd. (Found) for C18H15FN2O2: C, 69.67 (69.71); H, 4.87 (4.87); N, 9.03 (9.03).
3.4.1.7 Ethyl 1-(2-bromophenyl)-5-phenyl-1H-pyrazole-4-carboxylate (241g)
(2.0g, 68%); IR (KBr) cm–1
: 3550, 2855(Ar-H), C=N (1680-stretch of Pyrazole ring),
C=C (1585), C-O (1485), C=O (1680-stretch of ester); MS: m/z = 371.3 (M
+);
1H-
NMR (DMSO-d6): δ 8.2(s, 1H, pyrazole-CH), 7.68-7.66 (d, 1H, J = 7.9 Hz, Ar-H), 7.60-
7.58 (d, 1H, J = 7.76 Hz, Ar-H), 7.45-7.41 (m, 1H, Ar-H), 7.38-7.28 (m, 6H, Ar-H),
127
4.13-4.08(q, 2H), 1.12-1.09(t, 3H, J = 7.08 Hz). Anal. Calcd. (Found) for C18H15BrN2O2:
C, 58.24 (58.55); H, 4.07 (4.15); N, 7.55 (7.62).
3.4.1.8 Ethyl 5-phenyl-1-quinolin-2-yl-1H-pyrazole-4-carboxylate (241h)
(2.2 g, 81%); IR (KBr) cm–1
: 3068, 2976 (Ar-stretch), C=N (1599-stretch of Pyrazole
ring), C=C (1535), C-O (1455), C=O (1711-stretch of ester); MS: m/z = 344.3 (M
+);
1H-
NMR (DMSO-d6): δ 8.52-8.50 (d, 1H, J = 8.76 Hz, quinoline H), 8.2 (s, 1H, pyrazole-
CH), 8.01-7.99 (d, 1H, J = 8.08 Hz, Ar-H), 7.78-7.73 (d, 1H, J = 8.7 Hz, Ar-H), 7.70-
7.68 (t, 1H, J = 7.08 Hz, Ar-H), 7.62-7.58 (t, 1H, J = 7.96 Hz, Ar-H), 7.47-7.45 (d, 1H, J
= 8.36 Hz), 7.33-7.30 (m, 5H, Ar-H ), 4.15-4.09 (q, 2H), 1.14-1.05 (t, 3H, J = 7.12Hz).
13C NMR (DMSO-d6) 161.9, 150.0, 145.9, 145.2, 142.3, 139.3, 130.6, 130.2, 129.128.6,
128.1, 127.8, 127.4, 127.2, 126.8, 117.12, 114.33, 59.7, 13.9. Anal. Calcd. (Found) for
C21H17N3O2 : C 73.45 (73.45), H 4.99 (4.97), N 12.24 (12.20).
3.4.1.9 Ethyl 1-(4-methylphenyl)-5-phenyl-1H-pyrazole-4-carboxylate (241i)
(2.0g, 68%); IR (KBr) cm –1
: 3670, 2855 (Ar-H), C=N (1690-stretch of Pyrazole ring),
C=C (1545), C-O (1475), C=O (1640-stretch of ester); MS: m/z = 307.4 (M
+);
1H-NMR
(DMSO-d6): δ 8.15 (s, 1H, pyrazole-CH), 7.37-7.31 (m, 3H, Ar-H), 7.27-7.25 (t, 2H, J =
7.68 Hz, Ar-H), 7.14-7.12 (d, 1H, J = 8.321 Hz, Ar-H), 7.09-7.07 (d, 2H, J = 8.40 Hz,
Ar-H), 4.11-4.06 (q, 2H), 2.26 (s, 1H, -CH3 1.12-1.09 (t, 3H, J = 7.08 Hz). Anal. Calcd.
(Found) for C19H18N2O2: C, 74.49 (74.60); H, 5.92 (6.00); N, 9.14 (9.23).
3.4.1.10 Ethyl 1-tert-butyl-5-phenyl-1H-pyrazole-4-carboxylate (241j)
(1.5g, 71%); IR (KBr) cm –1
: 3630, 2835 (Ar-H), C=N (1630-stretch of Pyrazole ring),
C=C (1535), C-O (1435), C=O (1630-stretch of ester); MS: m/z = 273.3 (M
+);
1H-NMR
(DMSO-d6): δ 7.88 (s, 1H, Ar-H), 7.46-7.40 ( m, 3H, Ar-H), 7.34-7.31 (m, 2H, Ar-H),
3.93 (q, 2H), 1.35 (s, 9H, tert butyl), 0.94-0.90 (t, 3H, J = 7.12 Hz). Anal. Calcd.(Found)
for C16H20N2O2 : C, 70.56 (70.65); H, 7.40 (7.35); N, 10.29 (10.33).
128
3.4.1.11 Ethyl 1-methyl-5-phenyl-1H-pyrazole-4-carboxylate (241k)
(1.4g, 75%); IR (KBr) cm–1
: 3640, 2825 (Ar-H), C=N (1690-stretch of Pyrazole ring),
C=C (1565), C-O (1435), C=O (1700-stretch of ester); MS: m/z = 230.3 (M
+);
1H-NMR
(DMSO-d6): δ 8.33(s, 1H, pyrazole H), 7.47-7.33 ( m, 5H, Ar-H), 4.12-4.06 (q, 2H), 2.16
(s, 3H,-CH3), 1.10-1.06 (t, 3H, J = 7.08 Hz). Anal. Calcd.(Found) for C13H14N2O2: C,
67.81 (67.81); H, 6.13 (6.11); N, 12.17 (12.12).
3.4.1.12 Ethyl 1-(2, 4-dichlorophenyl)-5-phenyl-1H-pyrazole-4-carboxylate (241l)
(2.5g, 86.5%); IR (KBr) cm–1
: 3620, 2825(Ar-H), C=N (1620-stretch of Pyrazole ring),
C=C (1525), C-O (1425), C=O (1620-stretch of ester); MS: m/z =362.2 (M
+);
1H-NMR
(DMSO-d6): δ 8.22 (s, 1H, pyrazole-H), 8.21-7.4 ( m, 1H, Ar-H), 7.4-7.17 (m, 7H, Ar-
H), 4.14 (q, 2H), 1.13-1.09 (t, 3H, J = 7.08 Hz). Anal. Calcd. (Found) for C18H14Cl2N2O2 :
C, 59.85 (59.80); H, 3.91(3.97); N, 7.76 (7.72).
3.4.1.13 Ethyl 5-phenyl-1-piperidin-3-yl-1H-pyrazole-4-carboxylate (241m)
(2.0g, 83.3%); IR (KBr) cm–1
: 3620 (Ar-H), C=N (1650-stretch of Pyrazole ring), C=C
(1555), C-O (1455), C=O (1650-stretch of ester), MS: m/z =300.4 (M
+);
1H-NMR
(DMSO-d6): δ 8.01 (s, 1H, pyrazole H), 7.52-7.49 (m, 3H, Ar-H), 7.41-7.37 (m, 2H, Ar-
H), 4.13-4.06 (q, 2H), 3.92 (m, 1H), 3.1-2.9 (m, 3H), 2.8-2.49 (m, 1H), 2.01-1.96 (m,
2H), 1.67-1.64 (m, 1H), 1.33-1.30 (m, 1H), 1.10-1.06 (t, 3H, J = 7.08 Hz). Anal.
Calcd.(Found) for C17H21N3O2 : C, 68.20 (68.20); H, 7.07 (7.01); N, 14.04 (14.01).
3.4.1.14 Ethyl 1-cyclohexyl-5-phenyl-1H-pyrazole-4-carboxylate (241n)
(2.1g, 87.5%); IR (KBr) cm–1
: 3630 (Ar-H), C=N (1630-stretch of Pyrazole ring), C=C
(1535), C-O (1435), C=O (1630-stretch of ester), MS: m/z =299.4 (M
+);
1H-NMR
(DMSO-d6): δ 8.12 (s, 1H, pyrazole H), 7.65-7.25 ( m, 5H, Ar-H), 4.13-4.06 (q, 2H), 3.3-
3.2 (m, 1H), 3.1-2.5 (m, 2H), 2.45-2.20 (m, 4H), 2.2-1.99 (m, 4H), 1.12-1.07 (t, 3H, J =
129
7.08 Hz). Anal. Calcd. (Found) for C18H22N2O2 : C, 72.46 (72.50); H, 7.43 (7.39); N. 9.39
(9.39).
3.4.1.15 5-Phenyl-1-(quinolin-2-yl)-1H-pyrazole-4-carboxylic acid (242)
(TLC, Pet-ether/EtOAc, 1:1, Rf = 0.3) pale yellow solid.; 1H-NMR (DMSO-d6):12.55
(bs, 1H, -COOH), 8.51-8.49 (d, 1H, J = 8.72 Hz, Ar-H), 8.23 (s, 1H, Pyrazole-CH), 8.00-
7.98 (d, 1H, J = 7.40 Hz, Ar-H), 7.78-7.76 (d, 1H, J = 8.72 Hz, Ar-H), 7.71-7.70 (t, 1H,
J = 5.6 Hz, Ar-H), 7.68-7.61 (m, 1H, Ar-H), 7.45-7.43 (d, 1H, J = 8.40 Hz), 7.37-7.28
(m, 5H, Ar-H ). 13
C-NMR (DMSO-d6) 163.50, 150.19, 145.75, 145.27, 142.84, 139.24,
130.59, 130.26, 129.69, 128.46, 128.15, 127.87, 127.40, 127.23, 126.83, 117.19, 115.21.
MS: m/z = 316.3 (M
+) Method: A- 0.1%TFA, B-MEOH, Column: XBridge C18 (50 X
4.6 mm) 3.5 mm. Flow rate 2.0 mL/min.
3.4.1.16 Morpholin-4-yl [5-phenyl-1-(quinolin-2-yl)-1H-pyrazol-4-yl] methanone (243a)
(TLC, Pet-ether/EtOAc, 1:1, Rf = 0.5) pale yellow solid.; 1H-NMR (DMSO-d6): 8.55-8.52
(d, 1H, J = 8.76 Hz, Ar-H), 8.03 (s, 1H, Pyrazole-CH), 8.0 (s, 1H), 7.87-7.85 (d, 1H, J =
8.76 Hz, Ar-H), 7.72-7.70 (m, 1H, Ar-H), 7.69-7.68 (m, 1H, Ar-H), 7.45-7.43 (d, 1H, J =
8.36 Hz), 7.39-7.34 (m, 3H, Ar-H ), 7.33-7.25(m, 2H), 3.55-3.42 (m, 4H), 3.25-2.97 (m,
4H).13
C-NMR (DMSO-d6) 162.86, 150.36, 145.25, 141.16, 140.14, 139.32, 130.56,
129.64, 129.38, 128.64, 128.11, 128.03, 127.91, 127.03, 126.83, 118.31, 116.86, 65.63,
40.12. MS: m/z = 385.2 (M
+) Method: A- 0.1%TFA, B-MEOH, Column: XBridge C18
(50X4.6mm) 3.5mm. Flow rate 2.0mL/min. IR (KBr) cm–1
: 3065, 2957, 2905 (Ar-H),
C=N (1618-stretch of Pyrazole ring), C=C (1576), C-O (1425), C=O (1549-stretch of
ester); Anal. Calcd. (Found) for C23H20N4O2 : C 71.86 (71.87), H 5.24 (5.25), N
14.57(14.58).
3.4.1.17 [5-phenyl-1-(quinolin-2-yl)-1H-pyrazol-4-yl](piperazin-1-yl) methanone (243b)
130
(TLC, Chloroform: methanol, 8:2, Rf = 0.3) pale yellow solid.; 1H-NMR (DMSO-d6):
8.53-8.51 (d, 1H, J = 8.65 Hz, Ar-H), 8.02 (s, 1H, Pyrazole-CH), 8.0 (s, 1H), 7.86-7.84
(d, 1H, J = 8.75 Hz, Ar-H), 7.76-7.70 (m, 1H, Ar-H), 7.67-7.59 (m, 1H, Ar-H), 7.43-7.41
(d, 1H, J = 8.35 Hz), 7.38-7.33 (m, 3H, Ar-H ), 7.33-7.25 (m, 2H), 3.33-3.15 (m, 4H),
2.50-2.48 (m, 2H), 1.97-1.95(m, 2H).13
C-NMR (DMSO-d6) 162.68, 150.38, 145.26,
141.03, 140.01, 139.30, 130.54, 129.66, 129.36, 128.54, 128.07, 128.03, 127.91, 127.02,
126.82, 118.59, 116.86, 53.80, 45.17. MS: m/z = 384.2 (M
+) Method: A- 0.1%TFA, B-
MEOH, Column: XBridge C18 (50X4.6mm) 3.5mm. Flow rate 2.0mL/min. IR (KBr) cm–
1: 3096, 2939, 2789(Ar-H), C=N (1640-stretch of Pyrazole ring), C=C (1611), C-O
(1451), C=O (1593-stretch of ester); Anal. Calcd. (Found) for C23H21N5O : C 72.04
(72.05), H 5.52 (5.55), N 18.26(18.24).
3.4.1.18 (4-methylpiperazin-1-yl) [5-phenyl-1-(quinolin-2-yl)-1H-pyrazol-4-yl]
methanone (243c)
(TLC, Chloroform: methanol, 8:2, Rf = 0.38) pale yellow solid.; 1H-NMR (DMSO-d6):
8.54-8.52 (d, 1H, J = 8.68 Hz, Ar-H), 8.02 (s, 1H, Pyrazole-CH), 8.0 (s, 1H), 7.87-7.85
(d, 1H, J = 8.76 Hz, Ar-H), 7.72-7.69 (m, 1H, Ar-H), 7.62-7.58 (m, 1H, Ar-H), 7.46-7.44
(d, 1H, J = 8.36 Hz), 7.38-7.33 (m, 3H, Ar-H ), 7.33-7.23(m, 2H), 3.33-3.15 (m, 4H),
2.50-2.48 (m, 2H), 2.06(s, 3H), 1.97-1.95 (m, 2H).13
C-NMR (DMSO-d6) 162.68, 150.38,
145.26, 141.03, 140.01, 139.30, 130.54, 129.66, 129.36, 128.54, 128.07, 128.03, 127.91,
127.02, 126.82, 118.59, 116.86, 53.80, 45.17, 40.12. MS: m/z = 398.2 (M
+) Method: A-
0.1%TFA, B-MEOH, Column: XBridge C18 (50X4.6mm) 3.5mm. Flow rate 2.0 mL/min.
IR (KBr) cm–1
: 3096, 2939, 2789(Ar-H), C=N (1640-stretch of Pyrazole ring), C=C
(1611), C-O (1451), C=O (1593-stretch of ester); Anal. Calcd. (Found) for C24H23N5O : C
72.52 (72.53), H 5.83 (5.84), N 17.62(17.62).
131
3.4.1.19 N-cyclohexyl-5-phenyl-1-(quinolin-2-yl)-1H-pyrazole-4-carboxamide (243d)
(TLC, Pet ether: Ethyl acetate, 7:3, Rf = 0.41) pale yellow solid; 1H-NMR (DMSO-d6):
8.49-8.47 (d, 1H, J = 8.76 Hz, Ar-H), 8.23(s, 1H, Pyrazole-CH), 7.99-7.97 (d, 1H, J =
8.00 Hz, Ar-H), 7.800-7.77 (d, 1H, J = 8.72 Hz, Ar-H), 7.70-7.66 (m, 1H, Ar-H), 7.59-
7.57 (m, 1H), 7.56-7.55 (m, 1H), 7.51-7.49 (d, 1H, J = 7.84 Hz), 7.37-7.29 (m, 5H), 3.61
(m, 1H), 1.17-1.69 (m, 2H), 1.70-1.61 (m, 2H), 1.18-1.18 (m, 1H), 1.18-1.09(m, 5H).13
C-
NMR (DMSO-d6) 160.78, 150.41, 145.32, 143.25, 140.58, 139.22, 130.57, 130.28,
130.16, 128.39, 128.14, 127.91, 127.60, 127.09, 126.77, 119.15, 116.94, 47.57, 32.30,
25.22, 24.55. MS: m/z = 397.2 (M
+) Method: A- 0.1%TFA, B-MEOH, Column: XBridge
C18 (50X4.6mm) 3.5mm. Flow rate 2.0mL/min. IR (KBr) cm–1
: 3094, 2939, 2759(Ar-H),
C=N (1650-stretch of Pyrazole ring), C=C (1651), C-O (1451), C=O (1563-stretch of
ester); Anal. Calcd. (Found) for C25H24N4O : C 75.73 (75.74), H 6.10 (6.12), N
14.13(14.14).
3.4.1.20 N-cyclopentyl-5-phenyl-1-(quinolin-2-yl)-1H-pyrazole-4-carboxamide (243e)
(TLC, Pet ether: Ethyl acetate, 8:2, Rf = 0.34) pale yellow solid.; 1H-NMR (DMSO-d6):
8.50-8.47 (d, 1H, J = 8.68 Hz, Ar-H), 8.24(s, 1H, Pyrazole-CH), 7.99-7.97 (d, 1H, J =
7.04 Hz, Ar-H), 7.80-7.77 (1H, J = 8.76 Hz, Ar-H), 7.68-7.67 (m, 1H, Ar-H), 7.59-7.57
(m, 1H), 7.56-7.55(m, 1H), 7.51-7.49 (d, 1H, J = 7.84 Hz), 7.347.31(m, 5H), 4.12 (m,
1H), 1.78-1.74 (m, 3H), 1.53-1.35, 5H). 13
C-NMR (DMSO-d6) 160.78, 150.41, 145.32,
143.25, 140.58, 139.22, 130.57, 130.28, 130.16, 128.39, 128.14, 127.91, 127.60, 127.09,
126.77, 119.15, 116.94, 47.57, 32.30, 25.22. MS: m/z = 383 (M
+) Method: A- 0.1%TFA,
B-MEOH, Column: XBridge C18 (50X4.6mm) 3.5mm. Flow rate 2.0mL/min. IR (KBr)
cm–1
: 3094, 2939, 2759(Ar-H), C=N (1650-stretch of Pyrazole ring), C=C (1651), C-O
(1451), C=O (1563-stretch of ester); Anal. Calcd. (Found) for C24H22N4O : C 75.37
(75.34), H 5.80 (5.80), N 14.65(14.66).
132
3.4.1.21 N-(2, 6-dimethylphenyl)-5-phenyl-1-(quinolin-2-yl)-1H-pyrazole-4-
carboxamide (243f)
(TLC, Pet-ether/EtOAc, 7:3, Rf = 0.5) pale yellow solid.; 1H-NMR (DMSO-d6): 9.41(bs,
1H), 8.53-8.50 (d, 1H, J = 8.72 Hz, Ar-H), 8.42 (s, 1H, Pyrazole-CH), 7.83-7.81 (d, 1H, J
= 8.72 Hz, Ar-H), 7.72-7.70 (d, 1H, J = 7.0 Hz, Ar-H), 7.69-7.68 (m, 1H, Ar-H), 7.62-
7.58(m, 1H), 7.47-7.45 (d, 1H, J = 8.24 Hz, Ar-H), 7.38-7.27(m, 5H), 7.07(s, 3H), 2.14
(s, 6H). 13
C-NMR (DMSO-d6) 160.35, 150.35, 145.32, 143.97, 140.49, 139.23, 135.54,
134.88, 130.56, 130.24, 129.86, 128.34, 128.14, 127.88, 127.63, 127.48, 127.13, 126.81,
126.59, 118.61, 117.14, 18.10. MS: m/z = 419.3 (M
+) Method: A- 0.1%TFA, B-MEOH,
Column: XBridge C18 (50X4.6mm) 3.5mm. Flow rate 2.0mL/min. IR (KBr) cm–1
: 3394,
3223 (Ar-H), C=N (1644-stretch of Pyrazole ring), C=C (1500), C-O (1455), C=O (1597-
stretch of ester); Anal. Calcd. (Found) for C27H22N4O : C 77.79 (77.80), H 5.30 (5.31), N
13.39(13.37).
3.4.1.22 N, N-dimethyl-5-phenyl-1-(quinolin-2-yl)-1H-pyrazole-4-carboxamide (243g)
(TLC, Pet-ether/EtOAc, 1:1, Rf = 0.3) pale yellow solid.; 1H-NMR (DMSO-d6): 8.55-8.52
(d, 1H, J = 8.76 Hz, Ar-H), 8.03 (s, 1H, Pyrazole-CH), 8.0 (s, 1H), 7.87-7.85 (d, 1H, J =
8.76 Hz, Ar-H), 7.72-7.70 (m, 1H, Ar-H), 7.69-7.68 (m, 1H, Ar-H), 7.45-7.43 (d, 1H, J =
8.36 Hz), 7.39-7.34 (m, 3H, Ar-H ), 7.33-7.25(m, 2H), 2.95(s, 6H).13
C-NMR (DMSO-d6)
162.86, 150.36, 145.25, 141.16, 140.14, 139.32, 130.56, 129.64, 129.38, 128.64, 128.11,
128.03, 127.91, 127.03, 126.83, 118.31, 116.86, 41.9. MS: m/z = 343.3 (M
+) Method: A-
0.1%TFA, B-MEOH, Column: XBridge C18 (50X4.6mm) 3.5mm. Flow rate 2.0mL/min.
IR (KBr) cm–1
: 3065, 2957, 2905 (Ar-H), C=N (1618-stretch of Pyrazole ring), C=C
(1576), C-O (1425), C=O (1549-stretch of ester); Anal. Calcd. (Found) for C21H18N4O : C
73.67 (73.67), H 5.30 (5.32), N 16.36(16.34).
3.4.1.23 N, N-diethyl-5-phenyl-1-(quinolin-2-yl)-1H-pyrazole-4-carboxamide (243h)
133
(TLC, Pet-ether/EtOAc, 5:5, Rf = 0.5) pale yellow solid.; 1H-NMR (DMSO-d6): 8.55-8.52
(d, 1H, J = 8.76 Hz, Ar-H), 8.03 (s, 1H, Pyrazole-CH), 8.0 (s, 1H), 7.87-7.85 (d, 1H, J =
8.76 Hz, Ar-H), 7.72-7.70 (m, 1H, Ar-H), 7.69-7.68 (m, 1H, Ar-H), 7.45-7.43 (d, 1H, J =
8.36 Hz), 7.39-7.34 (m, 3H, Ar-H ), 7.33-7.25(m, 2H), 3.23-3.24( m, 4H), 1.15-1.08 (m,
6H). MS: m/z = 371.2 (M
+) Method: A- 0.1%TFA, B-MEOH, Column: XBridge C18
(50X4.6mm) 3.5mm. Flow rate 2.0mL/min. IR (KBr) cm–1
: 3065, 2957, 2905 (Ar-H),
C=N (1618-stretch of Pyrazole ring), C=C (1576), C-O (1425), C=O (1549-stretch of
ester); Anal. Calcd. (Found) for C23H22N4O : C 74.57 (74.58), H 5.99 (5.98), N
15.12(15.11).
3.4.1.24 Ethyl 5-(4-methoxyphenyl)-1-phenyl-1H-pyrazole-4-carboxylate (246a)
(2.0g, 86%); IR (KBr) cm–1
: 3102, 2991 (Ar-H), C=N (1614-stretch of Pyrazole ring),
C=C (1512), C-O (1223), C=O (1705 stretch of ester); MS: m/z = 324.1 (M+);
1H-NMR
(DMSO-d6): δ 8.14 (s, 1H, pyrazole -CH), 7.38-7.33 ( m, 3H, Ar-H), 7.22-7.21 (m, 2H),
7.20-7.18 (d, J = 8.8Hz, 2H), 6.90-6.88 (d, 2H, J = 9.6Hz), 4.14 (q, 2H), 3.70 (s, 3H, -
OMe group), 1.30 (t, 3H, J = 7.0Hz). 13
C NMR(DMSO-d6)162.12, 159.53, 145.13,
141.74, 138.99, 131.87, 128.94, 128.15, 125.61, 120.36, 113.33, 113.02, 59.54, 55.13,
14.04, Anal. Calcd. (Found) for C19H18N2O3: C, 70.79 (70.8); H, 5.63 (5.65); N, 8.69
(8.68).
3.4.1.25 Preparation of 4-[4-(ethoxycarbonyl)-5-(4-methoxyphenyl)-1H-pyrazol-1-yl]
benzoic acid (246b)
(2.2 g, 84 %); IR (KBr) cm–1
: 3500, 2990 (Ar-H), C=N (1600-stretch of Pyrazole ring),
C=C (1509), C-O (1230), C=O (1700-stretch of ester); MS: m/z = 366.3 (M
+);
1H-NMR
(DMSO-d6): δ 13.13 (bs, 1H, -COOH), 8.25 (s, 1H, pyrazole -CH), 7.88-7.86 (d, 2H, J =
8.56 Hz, Ar-H), 7.43-7.28 (m, 4H, Ar-H), 7.280-7.05 ( d, 2H, J = 8.60Hz, Ar-H), 4.13-
4.08 (q, 2H), 3.7(s, 3H), 1.12-1.08 (t, 3H, J = 7.12 Hz). 13
C NMR(DMSO-d6)165.15,
134
162.95, 145.33, 142.07, 139.00, 131.67, 130.44, 129.49, 128.78, 128.34, 127.98, 126.01,
113.62, 59.78, 55.28 13.83. Anal. Calcd.(Found) for C20H18N2O5 : C, 65.57 (65.58); H,
4.95 (4.96); N, 7.65 (7.64).
3.4.1.26 Preparation of 3-[4-(ethoxycarbonyl)-5-(4-methoxyphenyl)-1H-pyrazol-
1yl]benzoic acid (246c)
(2.1 g, 80 %); IR (KBr) cm–1
: 3453, 2996 (Ar-H), C=N (1634-stretch of Pyrazole ring),
C=C (1560), C-O (1300), C=O (1642-stretch of ester); MS: m/z = 367.3 (M
+);
1H-NMR
(DMSO-d6) : δ 13.17 (bs, 1H, -COOH), 8.21 (s, 1H, pyrazole -CH), 7.88-7.86 (d, 1H, J =
7.44 Hz, Ar-H), 7.78 (s, 1H, Ar-H), 7.47-7.29 (m, 7H, Ar-H), 4.13-4.07 (q, 2H), 3.7(s,
3H), 1.15-1.08 (t, 3H, J = 7.04 Hz). 13
C NMR(DMSO-d6)166.15, 161.95, 145.33, 142.07,
139.00, 131.67, 130.44, 129.49, 129.32, 129.20, 128.78, 128.34, 127.98, 126.01, 113.62.,
59.68, 55.58, 13.93. Anal. Calcd. (Found) for C20H18N2O5 : C, 65.57 (65.59); H, 4.95
(4.96); N, 7.65 (7.62).
3.4.1.27 Preparation of ethyl 1-(4-Isopropyl phenyl)-5-(4-methoxyphenyl)-1H-pyrazole-
4-carboxylate (246d)
(2.3g, 88%); IR (KBr) cm–1
: 3553, 2896 (Ar-H), C=N (1658-strecth of Pyrazole ring),
C=C (1567), C-O (1412), C=O (1650-stretch of ester); MS: m/z = 365.3 (M
+);
1H NMR
(DMSO-d6): δ 8.12 (s, 1H, pyrazole -CH), 7.23-7.18 (m, 4H, Ar-H), 7.14-7.12 (d, 2H, J =
8.9 Hz, Ar-H), 6.91-6.88 (d, 2H, J = 9.6Hz, Ar-H), 4.12-4.07 (q, 2H), 3.7(s, 3H, -OMe
group), 2.9-2.83(m, 1H), 1.16(s, 6H) 1.10-1.07 (t, 3H, J = 7.12 Hz), 13
C-NMR (DMSO-
d6) 162.11, 159.59, 148.28, 144.98, 141.57, 136.85, 131.83, 126.73, 125.35, 120.49,
113.31, 112.98, 59.47, 55.09, 23.60, 14.01. Anal. Calcd. (Found) for C22H24F3N2O3 : C,
72.50 (72.51); H, 6.64 (6.66); N, 7.69 (7.68).
135
3.4.1.28 Preparation of ethyl 1-(4-fluorophenyl)-5-(4-methoxy phenyl)-1H-pyrazole-4-
carboxylate (246e)
(2.0 g, 81%); IR (KBr) cm –1
: 3570, 2865 (Ar-H), C=N (1690-stretch of Pyrazole ring),
C=C (1575), C-O (1445), C=O (1670-stretch of ester); MS: m/z = 341.3 (M
+);
1H-NMR
(DMSO-d6): δ 8.17 (s, 1H, pyrazole -CH), 7.38-7.32 (m, 3H, Ar-H), 7.29-7.27 (m, 3H,
Ar-H), 7.27-7.18 (m, 2H, Ar-H), 4.12-4.07 (q, 2H), 3.74 (s, 3H), 1.11-1.08 (t, 3H, J =
7.08 Hz). Anal. Calcd. (Found) for C19H17FN2O3: C, 67.05 (67.05); H, 5.03 (5.03); N,
8.23 (8.22).
3.4.1.29 Preparation of ethyl 1-cyclohexyl-5-(4-methoxyphenyl)-1H-pyrazole-4
carboxylate (246f)
(1.5 g, 65%); IR (KBr) cm–1
: 2932, 2847 (Ar-H), C=N (1707-stretch of Pyrazole ring),
C=C (1508), C-O (1508), C=O (1612-stretch of ester), MS: m/z =329.3 (M
+);
1H-NMR
(DMSO-d6): δ 7.92 (s, 1H, pyrazole H), 7.30-7.03 ( d, 2H, J = 8.60Hz, Ar-H), 7.05-7.03
(d, 2H, J = 8.6Hz), 4.05-4.39 (q, 2H), 3.82 (m, 1H), 3.81 (s, 3H), 1.83-1.72(m, 6H),
1.56(m, 1H), 1.13 (m, 3H), 1.08-1.05(t, 3H, J = 7.08Hz). 13
C NMR(DMSO-d6) 162.20,
159.76, 144.45, 140.20, 131.23, 120.67, 113.68, 111.48, 59.10, 57.20, 55.16, 32.52,
24.81, 24.67, 14.01. Anal. Calcd. (Found) for C19H24N2O3 : C, 69.49 (69.50); H, 7.37
(7.39); N. 8.53 (8.52).
3.4.1.30 Preparation of ethyl 1-(4-tert-butylphenyl)-5-(4-methoxyphenyl)-1H-pyrazole-4-
carboxylate (246g)
(2.2g, 81%); IR (KBr) cm–1
: 3560, 2885 (Ar-H), C=N (1670-stretch of Pyrazole ring),
C=C (1585), C-O (1415), C=O (1660-stretch of ester); MS: m/z = 379.4 (M
+);
1H NMR
(DMSO-d6): δ 8.12 (s, 1H, pyrazole -CH), 7.23-7.18 (m, 4H, Ar-H), 7.14-7.12 (d, 2H, J =
8.9 Hz, Ar-H), 6.91-6.88 (d, 2H, J = 9.6Hz, Ar-H), 4.12-4.07 (q, 2H), 3.7(s, 3H, -OMe
136
group), , 1.25(s, 9H), 1.10-1.07 (t, 3H, J = 7.08 Hz). Anal. Calcd.(Found) for
C23H26N2O3: C, 72.99 (73.0); H, 6.92 (6.94); N, 7.40 (7.39).
3.4.1.31 Preparation of ethyl 1-(4-methylphenyl)-5-(4-methoxyphenyl)-1H-pyrazole-4-
carboxylate (246h)
(1.4g, 64%); IR (KBr) cm –1
: 3670, 2855 (Ar-H), C=N (1690-stretch of Pyrazole ring),
C=C (1545), C-O (1475), C=O (1640-stretch of ester); MS: m/z = 338.4 (M
+);
1H-NMR
(DMSO-d6): δ 8.15 (s, 1H, pyrazole-CH), 7.37-7.31 (m, 2H, Ar-H), 7.27-7.25 (t, 2H, J =
7.68 Hz, Ar-H), 7.14-7.12 (d, 1H, J = 8.32 Hz, Ar-H), 7.09-7.07 (d, 2H, J = 8.40 Hz, Ar-
H), 4.11-4.06 (q, 2H), 3.69(s, 3H), 2.26 (s, 3H, -CH3), 1.12-1.09 (t, 3H, J = 7.08 Hz). 13
C
NMR(DMSO-d6)162.04, 145.12, 141.55, 137.78, 136.45, 130.40, 129.33, 128.96, 128.65,
127.84, 125.41, 113.17, 59.56, 55.38, 20.51, 13.94. Anal. Calcd. (Found) for C20H20N2O3:
C, 71.41 (71.43); H, 5.99 (6.00); N, 8.33 (8.30).
3.4.1.32 Preparation of ethyl 1-tert-butyl-5-(4-methoxy phenyl)-1H-pyrazole-4
carboxylate (246i)
(1.45g, 68%); IR (KBr) cm –1
: 3630, 2835 (Ar-H), C=N (1630-stretch of Pyrazole ring),
C=C (1535), C-O (1435), C=O (1630-stretch of ester); MS: m/z = 302.4 (M
+);
1H-NMR
(DMSO-d6): 1H-NMR (DMSO-d6): δ 7.92 (s, 1H, pyrazole H), 7.30-7.03 ( d, 2H, J =
8.60Hz, Ar-H), 7.05-7.03 (d, 2H, J = 8.6Hz), 3.93 (q, 2H), 3.75(s, 3H), 1.35 (s, 9H, tert
butyl), 0.94-0.90 (t, J = 7.12 Hz, 3H). Anal. Calcd.(Found) for C17H27N2O3 : C, 67.53
(67.59); H, 7.33 (7.35); N, 9.26 (9.30).
3.4.1.33 Preparation of ethyl 5-(4-methoxyphenyl)-1-(quinolin-2-yl)-1H-pyrazole-4-
carboxylate (246j)
(1.9g, 79%); IR (KBr) cm–1
: 3530, 2835 (Ar-H), C=N (1630-stretch of Pyrazole ring),
C=C (1535), C-O (1455), C=O (1680-stretch of ester); MS: m/z = 375.3 (M
+);
1H-NMR
(DMSO-d6): δ 8.52-8.50 (d, 1H, J = 8.76 Hz, quinoline H), 8.2 (s, 1H, pyrazole-CH),
137
8.01-7.99 (d, 1H, J = 8.08 Hz, Ar-H), 7.78-7.73 (d, 1H, J = 8.7 Hz, Ar-H), 7.70-7.68 (t,
1H, J = 7.08 Hz, Ar-H), 7.62-7.58 (t, 1H, J = 7.96 Hz, Ar-H), 7.47-7.45 (d, 1H, J = 8.36
Hz), 7.33-7.30 (m, 4H, Ar-H ) 4.15-4.09 (q, 2H), 3.78(s, 3H), 1.14-1.05 (t, 3H, J =
7.12Hz). 13
C NMR(DMSO-d6) 161.91, 150.06, 145.98, 145.25, 142.36, 139.31, 130.63,
130.20, 129.45, 128.60, 128.15, 127.88, 127.40, 127.28, 126.87, 117.12, 114.33, 59.77,
55.60, 13.90. Anal. Calcd. (Found) for C22H19N3O3 : C 70.76 (70.77), H 5.13 (5.14), N
11.25(11.24).
3.4.1.34 Preparation of ethyl 1-(2-bromophenyl)-5-(4-methoxy phenyl)-1H-pyrazole-4-
carboxylate (246k)
(2.5g, 89%); IR (KBr) cm–1
: 3550, 2855(Ar-H), C=N (1680-stretch of Pyrazole ring),
C=C (1585), C-O (1485), C=O (1680-stretch of ester); MS: m/z = 402.04 (M
+);
1H- NMR
(DMSO-d6): δ 8.2(s, 1H, pyrazole-CH), 7.68-7.66 (d, 1H, J = 7.9 Hz, Ar-H), 7.60-7.58 (d,
1H, J = 7.76 Hz, Ar-H), 7.45-7.41 (m, 1H, Ar-H), 7.38-7.28 (m, 5H, Ar-H), 4.13-4.08(q,
2H), 3.69(s, 3H), 1.12-1.09(t, 3H, J = 7.08 Hz). 13
C NMR(DMSO-d6) 162.04, 146.74,
141.84, 137.94, 133.01, 131.59, 130.77, 130.13, 129.13, 128.39, 127.82, 127.61, 121.59,
112.55, 59.67, 55.6, 13.95. Anal. Calcd. (Found) for C19H17BrN2O2: C, 56.87 (56.89); H,
4.27 (4.25); N, 6.98 (6.97).
3.4.1.35 Preparation of ethyl 5-(4-methoxy phenyl)-1-piperidin-4-yl-1H-pyrazole-4-
carboxylate (246l)
(1.5g, 65%); IR (KBr) cm–1
: 3620 (Ar-H), C=N (1650-stretch of Pyrazole ring), C=C
(1555), C-O (1455), C=O (1650-stretch of ester), MS: m/z =330.4 (M
+);
1H-NMR
(DMSO-d6): δ 7.92 (s, 1H, pyrazole H), 7.35-7.05 ( d, 2H, J = 8.60Hz, Ar-H), 7.08-7.08
(d, 2H, J = 8.6Hz), 4.13-4.06 (q, 2H), 3.92 (m, 1H), 3.7(s, 3H), 3.1-2.9 (m, 3H), 2.8-2.49
(m, 1H), 2.01-1.96 (m, 2H), 1.67-1.64 (m, 1H), 1.33-1.30 (m, 1H), 1.10-1.06 (t, J = 7.08
Hz, 3H). 13
C NMR(DMSO-d6) 162.05, 145.11, 140.43, 129.89, 129.23, 128.62, 127.64,
138
111.86, 59.24, 55.23, 54.82, 53.23, 52.65, 50.10, 24.44, 13.88. Anal. Calcd. (Found) for
C18H23N3O3 : C, 65.63 (65.65); H, 7.04 (7.08); N, 12.76 (12.75).
3.4.1.36 Preparation of 5-(4-methoxyPhenyl)-1-[4-(propan-2-yl) phenyl]-1H-pyrazole-
4-carboxylic acid (247)
Yield 91.3%, white solid. (TLC, Pet-ether/EtOAc, 1:1, Rf = 0.3) pale yellow
solid.; 1H-NMR (DMSO-d6):12.09 (bs, 1H, -COOH), 8.08-8.07 (s, 1H, Pyrazole-CH),
7.23-7.20 (d, 2H, J = 8.44 Hz, Ar-H), 7.20-7.18 (d, 2H, J = 8.48 Hz, Ar-H), 7.12-7.10 (d,
2H, J = 8.32 Hz, Ar-H), 6.89-6.87 (d, 2H, J = 8.52 Hz, Ar-H), 3.74 (s, 3H), 2.90-2.83 (m,
1H ), 1.16 (s, 6H). 13
C-NMR (DMSO-d6) 163.72, 159.45, 148.14, 144.76, 142.03, 137.00,
131.86, 126.70, 125.37, 120.76, 113.81, 113.31, 55.07, 32.89, 23.63. MS: m/z = 337.3
(M+) Method: A- 0.1%TFA, B-MEOH, Column: XBridge C18 (50X4.6mm) 3.5mm.
Flow rate 2.0mL/min. Anal. Calcd. (Found) for C20H20N2O3 : C, 71.41 (71.45); H, 5.99
(5.60); N, 8.33 (8.32
3.4.1.37 {5-(4-methoxy Phenyl) -1-[4-(propan-2-yl) phenyl]-1H-pyrazol-4-yl}
(piperazin-1-yl) methanone (248a)
(TLC, Chloroform: methanol, 8:2, Rf = 0.3) pale yellow solid.; 1H-NMR (DMSO-d6):
7.83 (s, 1H, Pyrazole-CH), 7.26-7.24 (d, 2H, J = 8.48 Hz, Ar-H), 7.17-7.14(m, 2H), 7.10-
7.07 (m,2H), 6.94- 6.92(d, 2H, J = 8.84 Hz, Ar-H), 3.74 (s, 3H), 3.4-3.32(m,4H), 2.92-
2.85(m, 1H), 2.50-2.48 (m, 2H), 1.97-1.95(m, 2H), 1.18 (d, J = 6.9 Hz, 6H, -isopropyl H).
MS: m/z = 405.2
(M+) Method: A- 0.1%TFA, B-MEOH, Column: XBridge C18
(50X4.6mm) 3.5mm. Flow rate 2.0mL/min. IR (KBr) cm–1
: 2936, 2923, 2861, (Ar-H),
C=N (1626-stretch of Pyrazole ring), C=C (1556), C-O (1456), C=O (1513-stretch of
ester); Anal. Calcd. (Found) for C24H28N4O2 : C 71.26 (71.28), H 6.98 (6.98), N
13.85(13.86).
139
3.4.1.38{5-(4-methoxy Phenyl)-1-[4-(propan-2-yl) phenyl]-1H-pyrazol-4-yl}(morpholin-
4-yl) methanone (248b)
(TLC, Pet-ether/EtOAc, 8:2, Rf = 0.4) pale yellow solid.; 1H-NMR (DMSO-d6): 7.83 (s,
1H, Pyrazole-CH), 7.26-7.24 (d, 2H, J = 8.48 Hz, Ar-H), 7.17-7.14(m, 2H), 7.10-7.07
(m,2H), 6.94- 6.92(d, 2H, J=8.84 Hz, Ar-H), 3.74 (s, 3H), 3.4-3.32(m,4H), 3.32-3.30(m,
4H), 2.92-2.85(m, 1H), 1.18 (d, J = 6.9 Hz, 6H, -isopropyl H).13
C-NMR (DMSO-d6)
163.34, 159.56, 147.99, 140.31, 139.03, 137.12, 130.76, 126.79, 125.18, 120.88, 116.46,
114.10, 65.71, 55.18, 32.90, 23.67. MS: m/z = 406.2 (M
+) Method: A- 0.1%TFA, B-
MEOH, Column: XBridge C18 (50X4.6mm) 3.5mm. Flow rate 2.0mL/min. IR (KBr) cm–
1: 2936, 2923, 2861, (Ar-H), C=N (1626-stretch of Pyrazole ring), C=C (1556), C-O
(1456), C=O (1513-stretch of ester); Anal. Calcd. (Found) for C24H27N3O3 : C 71.06
(71.08), H 6.71 (6.72), N 10.36(10.32).
3.4.1.39 (4-Methylpiperazin-1-yl) {5-(4-methoxy phenyl)-1-[4-(propan-2-yl)phenyl]-1H-
pyrazol-4-yl}methanone (248c)
(TLC, Chloroform: methanol, 8:2, Rf = 0.3) pale yellow solid.; 1H-NMR (DMSO-d6):
7.83 (s, 1H, Pyrazole-CH), 7.26-7.24 (d, 2H, J = 8.48 Hz, Ar-H), 7.17-7.14(m, 2H), 7.10-
7.07 (m,2H), 6.94- 6.92(d, 2H, J = 8.84 Hz, Ar-H), 3.74 (s, 3H), 3.4-3.32(m,4H), 2.92-
2.85(m, 1H), 2.50-2.48 (m, 2H), 1.97-1.95(m, 2H), 1.18 (d, J = 6.9 Hz, 6H, -isopropyl H).
MS: m/z = 419.2
(M+) Method: A- 0.1%TFA, B-MEOH, Column: XBridge C18
(50X4.6mm) 3.5mm. Flow rate 2.0mL/min. IR (KBr) cm–1
: 2936, 2923, 2861, (Ar-H),
C=N (1626-stretch of Pyrazole ring), C=C (1556), C-O (1456), C=O (1513-stretch of
ester); Anal. Calcd. (Found) for C24H28N4O2 : C 71.26 (71.28), H 6.98 (6.98), N
13.85(13.86).
140
3.4.1.40 N-cyclohexyl-5-(4-methoxy phenyl)-1-[4-(propan-2-yl) phenyl]-1H-pyrazole-4-
carboxamide (248d)
(TLC, Pet ether: Ethyl acetate, 8:2, Rf = 0.31) pale yellow solid.; 1H-NMR (DMSO-d6):
8.07 (s, 1H, Pyrazole-CH), 7.52-7.50 (d, 1H, J =7.13 Hz, Ar-H), 7.20-7.14 (m, 4H, Ar-
H), 7.10-7.08(d, 2H, J = 8.24 Hz, Ar-H), 6.89-6.87 (d, 2H, J = 8.55 Hz, Ar-H), 4.07-4.03
(m, 1H), 3.74(s, 3H), 3.6-3.65(m, 1H), 1.78-1.74(m, 4H), 1.56-1.37 (m, 6H), 1.37-1.35(d,
J = 6.0 Hz, 6H, isopropyl H).13
C-NMR (DMSO-d6) 161.54, 159.38, 147.87, 142.24,
139.47, 137.16, 131.77, 126.68, 125.16, 121.14, 117.59, 113.45, 55.12, 50.25, 32.88,
32.17, 23.65, 23.39, 23.22. MS: m/z = 418.3 (M
+) Method: A- 0.1%TFA, B-MEOH,
Column: XBridge C18 (50X4.6mm) 3.5mm. Flow rate 2.0mL/min. IR (KBr) cm–1
: 3289,
2950 (Ar-H), C=N (1622-stretch of Pyrazole ring), C=C (1517), C-O (1456), C=O (1579-
stretch of ester); Anal. Calcd. (Found) for C25H29N3O2 : C 74.79 (74.82), H 7.48 (7.49), N
10.06(10.09).
3.4.1.41 5-(4-Methoxy Phenyl)-N-2, 6-dimethyl phenyl-1-[4-(propan-2-yl) phenyl]-1H-
pyrazole-4-carboxamide (248e)
(TLC, Pet-ether/EtOAc, 8:2, Rf = 0.6) pale yellow solid.; 1H-NMR (DMSO-d6): 9.41(bs,
1H), 8.07 (s, 1H, Pyrazole-CH), 7.52-7.50 (d, 1H, J = 7.13 Hz, Ar-H), 7.20-7.14 (m, 6H,
Ar-H), 7.10-7.08(d, 2H, J = 8.24 Hz, Ar-H), 6.89-6.87 (d, 2H, J = 8.55 Hz, Ar-H), 4.07-
4.03 (m, 1H), 3.74(s, 3H), 2.14 (s, 6H), 1.37-1.35(d, J = 6.0 Hz, 6H, isopropyl H). 13
C-
NMR (DMSO-d6) 161.54, 159.38, 147.87, 142.24, 139.47, 137.16, 131.77, 126.68,
125.16, 121.14, 117.59, 113.45, 23.65, 23.39, 18.10. MS: m/z = 440.2 (M
+) Method: A-
0.1%TFA, B-MEOH, Column: XBridge C18 (50X4.6mm) 3.5mm. Flow rate 2.0mL/min.
IR (KBr) cm–1
: 3289, 2950 (Ar-H), C=N (1622-stretch of Pyrazole ring), C=C (1517), C-
O (1456), C=O (1579-stretch of ester); Anal. Calcd. (Found) for C28H29N3O2 : C 76.51
(76.51), H 6.65 (6.65), N 9.56 (9.50).
141
3.4.1.42 N-cyclopentyl-5-(4-methoxy phenyl-1-[4-(propan-2-yl) phenyl]-1H-pyrazole-4-
carboxamide (248f)
(TLC, Pet ether: Ethyl acetate, 8:2, Rf = 0.34) pale yellow solid.; 1H-NMR (DMSO-d6):
8.08 (s, 1H, Pyrazole-CH), 7.50-7.48 (d, 1H, J = 7.16 Hz, Ar-H), 7.22-7.16 (m, 4H, Ar-
H), 7.10-7.08(d, 2H, J = 8.28 Hz, Ar-H), 6.89-6.87 (d, 2H, J = 8.56 Hz, Ar-H), 4.07-4.03
(m, 1H), 3.74(s, 3H), 3.6-3.65(m,1H), 2.88-2.85(m, 1H), 1.78-1.74(m, 2H), 1.56-1.37 (m,
6H), 1.37-1.35(d, J = 6.0 Hz, 6H, isopropyl H).13
C-NMR (DMSO-d6) 161.54, 159.38,
147.87, 142.24, 139.47, 137.16, 131.77, 126.68, 125.16, 121.14, 117.59, 113.45, 55.12,
50.25, 32.88, 32.17, 23.65, 23.39. MS: m/z = 404.3 (M
+) Method: A- 0.1%TFA, B-
MEOH, Column: XBridge C18 (50X4.6mm) 3.5mm. Flow rate 2.0mL/min. IR (KBr) cm–
1: 3289, 2950 (Ar-H), C=N (1622-stretch of Pyrazole ring), C=C (1517), C-O (1456),
C=O (1579-stretch of ester); Anal. Calcd. (Found) for C25H29N3O2 : C 74.41 (74.43), H
7.24 (7.25), N 10.41(10.32).
3.4.1.43 N, N-dimethyl-5-(4-methoxy phenyl)-1-[4-(propan-2-yl) phenyl]-1H-pyrazole-4-
carboxamide (248g)
(TLC, Pet-ether/EtOAc, 1:1, Rf = 0.3) pale yellow solid.; 1H-NMR (DMSO-d6): 7.98 (s,
1H, Pyrazole-CH), 7.32-7.12 (d, 2H, J = 8.44 Hz, Ar-H), 7.20-7.18 (d, 2H, J = 8.48 Hz,
Ar-H), 7.12-7.10 (d, 2H, J = 8.32 Hz, Ar-H), 6.89-6.87 (d, 2H, J = 8.52 Hz, Ar-H), 3.74
(s, 3H), 2.90-2.83 (m, 1H ), 2.14 (s, 6H), 1.16 (s, 6H). 13
C-NMR (DMSO-d6) 163.72,
159.45, 148.14, 144.76, 142.03, 137.00, 131.86, 126.70, 125.37, 120.76, 113.81, 113.31,
55.07, 32.89, 23.63, 18.25. MS: m/z = 364.3 (M
+) Method: A- 0.1%TFA, B-MEOH,
Column: XBridge C18 (50X4.6mm) 3.5mm. Flow rate 2.0mL/min. Anal. Calcd. (Found)
for C22H25N3O2 : C, 72.70 (72.70); H, 6.93 (6.95); N, 11.56 (11.53).
142
3.4.1.44 N, N-diethyl-5-(4-methoxy phenyl)-1-[4-(propan-2-yl) phenyl]-1H-pyrazole-4-
carboxamide (248h)
(TLC, Pet-ether/EtOAc, 5:5, Rf = 0.45) pale yellow solid.; 1H-NMR (DMSO-d6): 8.08-
8.07 (s, 1H, Pyrazole-CH), 7.23-7.20 (d, 2H, J = 8.44 Hz, Ar-H), 7.20-7.18 (d, 2H, J =
8.48 Hz, Ar-H), 7.12-7.10 (d, 2H, J = 8.32 Hz, Ar-H), 6.89-6.87 (d, 2H, J = 8.52 Hz, Ar-
H), 3.74 (s, 3H), 3.23-3.24( m, 4H), 2.90-2.83 (m, 1H ), 2.14 (s, 6H), 1.15-1.08 (m, 6H).
MS: m/z = 392.3
(M+) Method: A- 0.1%TFA, B-MEOH, Column: XBridge C18
(50X4.6mm) 3.5mm. Flow rate 2.0mL/min. IR (KBr) cm–1
: 3065, 2957, 2905 (Ar-H),
C=N (1618-stretch of Pyrazole ring), C=C (1576), C-O (1425), C=O (1549-stretch of
ester); Anal. Calcd. (Found) for C24H29N3O2 : C 73.63 (73.68), H 7.47 (7.48), N
10.73(10.72).
143
3.4.2. Spectral data
Fig. 3.14: 1H NMR spectrum of 4-[4-(Ethoxycarbonyl)-5-phenyl-1H-pyrazol-1-yl]
benzoic acid (241b)
NN
O OH
O
O
(241b)
144
Fig. 3.15: NOESY spectrum of 4-[4-(Ethoxycarbonyl)-5-phenyl-1H-pyrazol-1-yl]
benzoic acid (241b)
Fig. 3.16: NOE spectrum of 4-[4-(Ethoxycarbonyl)-5-phenyl-1H-pyrazol-1-yl] benzoic
acid (241b)
NN
O OH
O
O
(241b)
NN
O OH
O
O
(241b)
145
Fig. 3.17: 1H NMR spectrum of ethyl 5-phenyl-1-quinolin-2-yl-1H-pyrazole-4-
carboxylate (241h)
Fig. 3.18: 13
C NMR spectrum of ethyl 5-phenyl-1-quinolin-2-yl-1H-pyrazole-4-
carboxylate (241h)
NN
O
O
N
241h
NN
O
O
N
241h
146
Fig. 3.19: IR Spectrum of ethyl 5-phenyl-1-quinolin-2-yl-1H-pyrazole-4-carboxylate (241h)
Fig. 3.20: 1H NMR spectrum of ethyl 1-tert-butyl-5-phenyl-1H-pyrazole-4-carboxylate
(241j)
NN
O
O
N
241h
NN
O
O
241j
147
Fig. 3.21: X-ray crystal structure of compound Ethyl 1-tert-butyl-5-phenyl-1H-pyrazole-
4-carboxylate (241j)
Fig. 3.22: 1
H NMR spectrum of (4-methylpiperazin-1-yl) [5-phenyl-1-(quinolin-2-yl)-1H-
pyrazol-4-yl] methanone (243c)
O
NN
N
N
N
243c
148
Fig. 3.23: 13C NMR spectrum of (4-methylpiperazin-1-yl) [5-phenyl-1-(quinolin-2-yl)-
1H-pyrazol-4-yl] methanone (243c)
O
NN
N
N
N
243c
149
Fig 3.24: LCMS spectrum of (4-methylpiperazin-1-yl) [5-phenyl-1-(quinolin-2-yl)-1H-
pyrazol-4-yl] methanone (243c)
O
NN
N
N
N
243c
Mass:397
150
Fig. 3.25: 1H NMR spectrum of ethyl 1-cyclohexyl-5-(4-methoxyphenyl)-1H-pyrazole-4
carboxylate (246f)
Fig. 3.26: 13
C NMR spectrum of ethyl 1-cyclohexyl-5-(4-methoxyphenyl)-1H-pyrazole-4
carboxylate (246f)
N
N
O
O
O
246f
N
N
O
O
O
246f
151
Fig. 3.27: X-ray crystal structure of compound ethyl 1-cyclohexyl-5-(4-methoxyphenyl)-
1H-pyrazole-4 carboxylate (246f)
Fig. 3.28: 1H NMR spectrum of {5-(4-methoxy Phenyl)-1-[4-(propan-2-yl) phenyl]-1H-
pyrazol-4-yl}(morpholin-4-yl)methanone (248b)
N
N
O
O
O
246f
O
N
O
NN
O
248b
152
Fig. 3.29: 13
CNMR spectrum of {5-(4-methoxy Phenyl)-1-[4-(propan-2-yl) phenyl]-1H-
pyrazol-4-yl}(morpholin-4-yl)methanone (248b)
O
N
O
NN
O
248b
153
Fig. 3.30: LC MS spectrum of {5-(4-methoxy Phenyl)-1-[4-(propan-2-yl) phenyl]-1H-
pyrazol-4-yl}(morpholin-4-yl)methanone (248b)
O
N
O
NN
O
248b
154
Fig. 3.31: IR Spectrum of {5-(4-methoxy Phenyl)-1-[4-(propan-2-yl) phenyl]-1H-
pyrazol-4-yl}(morpholin-4-yl)methanone (248b)
Fig. 3.32: 1H NMR spectrum of N-cyclopentyl-5-(4-methoxy phenyl-1-[4-(propan-2-yl)
phenyl]-1H-pyrazole-4-carboxamide (248f)
O
N
O
NN
O
248b
NN
O
HN
O
248f
155
Fig. 3.33: 13
C NMR spectrum of N-cyclopentyl-5-(4-methoxy phenyl-1-[4-(propan-2-yl)
phenyl]-1H-pyrazole-4-carboxamide (248f)
NN
O
HN
O
248f
156
3.5 Biological activity
3.5.1 In vitro antibacterial studies of ethyl-1-(N-substituted) 5-phenyl-1H-pyrazole-4
carboxylate derivative 241(a-n) and 243(a-h)
All the newly synthesized compounds were screened for their antibacterial
activity. The antibacterial activity of the 241(a-n) series was assessed by MIC by serial
dilution method.35
For this, Staphylococcus aureus, Bacillus subtilis, Escherichia coli and
Pseudomonas aeruginosa microorganisms were employed. Antimicrobial study was
assessed by MIC by serial dilution method.34
Several colonies of S. aureus, B. subtilis, E.
coli and P. aeruginosa were picked off a fresh isolation plate and inoculated in
corresponding tubes containing 5 mL of trypticase soya broth. The broth was incubated
for 6 h at 37 oC until there was visible growth. Mc Farland No.5 standard was prepared by
adding 0.05 mL of 1% w/v BaCl2.2H2O in Phosphate Buffered Saline (PBS) to 9.95 mL
of 1% v/v H2SO4 in PBS. The growth of all the four cultures was adjusted to Mc Farland
No.5 turbidity standard using sterile PBS. This gives a 108
cfu/mL suspension. The
working inoculums of afore mentioned four different microorganisms containing 105
cfu/
mL suspension was prepared by diluting the 108
cfu/ mL suspension, 103 times in
trypticase soya broth.
3.5.1.1. Preparation of anti-microbial suspension (50 µg/ mL).
Dissolved 0.5 mg of each compound in 10 mL of trypticase soya broth to get 50µg/mL.
This suspension was filter sterilized in syringe filters.
3.5.1.2. Preparation of dilutions
In all, for each of the 14 anti-microbial compounds and standard antimicrobial i.e
Ceftriaxone, 24 tubes of 5 mL capacity were arranged in 4 rows with each row containing
6 tubes. Then 1.9 mL of trypticase soya broth was added in the first tube in each row and
1 mL in the remaining tubes. Now, 100µl of filtered anti microbial suspension was added
157
to the first tube in each row and after mixing the content, 1 mL was serially transferred
from these tubes to the second tube in each of the rows. The contents in the second tube
of each of the rows were mixed and transferred to the third tube in each of the rows. This
serial dilution was repeated till the sixth tube in each of the rows. This provided anti
microbial concentrations of 50, 25, 12.5, 6.25, 3.125, 1.6125 µg / mL in the first to sixth
tube respectively in each row. Finally, 1 mL of 105
cfu/ mL of S. aureus, B. subtilis, E.
coli and P. aerogenosa suspension were added to the first, second, third and fourth rows
of tubes respectively. Along with the test samples and Ceftriaxone (standard), the
inoculums control (without antimicrobial compound) and broth control (without
antimicrobial compound and inoculum) were maintained. All the test sample and control
tubes were then incubated for 16 h at 37 oC.
3.5.1.3. Interpretation
After incubation, the tubes showing no visible growth were considered to be
representing the MIC. The details of results are furnished in Table-3.5. Inoculums control
showed visible growth, where as the broth control showed no growth.
Table-3.5: Antibacterial data for the newly synthesized Pyrazole ester derivatives in MIC
µg/mL 241 (a-n)
Com.No. S. aureus B.subtilis E.coli P.aeruginosa
241a Growth in all
concentrations
50
Growth in all
concentrations
1.6125
241b 50 Growth in all
concentrations
Growth in all
concentrations
25.0
241c Growth in all
concentrations
Growth in all
concentrations
Growth in all
concentrations
Growth in all
concentrations
241d 3.125 1.6125 1.6125 1.6125
241e Growth in all
concentrations
12.50 Growth in all
concentrations
12.50
241f 6.250 3.125 1.6125 1.6125
241g 3.125 1.6125 1.6125 1.6125
241h 3.125 3.125 6.250 3.125
158
241i Growth in all
concentrations
Growth in all
concentrations
Growth in all
concentrations
Growth in all
concentrations
241j Growth in all
concentrations
Growth in all
concentrations
Growth in all
concentrations
Growth in all
concentrations
241k Growth in all
concentrations
Growth in all
concentrations
Growth in all
concentrations
Growth in all
concentrations
241l 1.6125 1.6125 1.6125 3.250
241m 3.125 3.125 1.6125 1.6125
241n 6.250 6.250 12.50 6.250
Ceftriaxone
(standard)
3.125 1.6125 1.6125 1.6125
Inoculum
Control
Growth in all
concentrations
Growth in all
concentrations
Growth in all
concentrations
Growth in all
concentrations
Broth
Control
No growth No growth No growth No growth
The antibacterial activity of the 243 (a-h) was done using Bacillus subtilis MTCC
441, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. The
above activity was examined qualitatively and quantitatively by the presence or absence
of inhibition zones and zone diameter. Susceptibility of the test organism to the organic
compound was determined by well plate technique.36,37
Each strain was inoculated in to
10 mL Tryptone soya broth (TSB) in 50 mL conical flask, and was incubated at 37 ºC till
they showed good growth. From the well grown flask 60 µl of the inoculum was spread
uniformly on the pre-set media plates. The wells were dug by sterilized cork borer and
organic compound dissolved in DMSO (1 mg/mL and 0.5 mg/mL concentration) were
added. Same procedure was repeated for all micro-organisms, the Petri plates were
incubated for 24 h at 37 oC. Here DMSO was used as negative control and Streptomycin
as positive controls. The plates were checked for zone of inhibition, the compounds
which showed good zone inhibition, were studied for MIC. MIC was performed at
different concentration 1, 10, 25, 50, 100, 500 and 1000 µg/mL. 100 µl of the inoculum
was uniformly spread onto preset plates and then place sterile filter paper disks (5 mm
diameter) on the spread plates. The filter paper disk was loaded with 5 µl of the sample of
159
different concentration before starting the experiment aseptically. TSA plates were
incubated at 37 ºC for 24 h. The antibacterial screening revealed that some of the tested
compounds showed good inhibition against various tested microbial strains.
Table-3.6: Antibacterial data for the newly synthesized Pyrazole carboxamide derivatives
243 (a-h)
Organic
compound
Escherichia
coli
Bacillus
subtilis
Pseudomonas
aeruginosa
Concentration
In mg/mL
1 0.5 1 0.5 1 0.5
Streptomycin 17±0.2 15±0.1 20±0.3 17±0.2 16±0.1 13±0.1
Control 00 00 00 00 00 00
243a - - - - - -
243b 05±0.3 03±0.2 04±0.2 02±0.1 06±0.1 04±0.2
2439c - - - - - -
243d 08±0.2 05±0.1 07±0.1 05±0.2 07±0.2 04±0.3
243e - - - - - -
243f 10±0.3 08±0.2 07±0.2 05±0.2 07±0.2 04±0.1
243g 06±0.1 04±0.2 05±0.3 04±0.2 05±0.2 03±0.1
243h 11±0.2 09±0.1 10±0.2 07±0.3 11±0.2 08±0.1
Table 3.7: Minimum Inhibitory Concentration (MIC µg/mL): 243(a-h)
Organic
compound
Escherichia
coli
Bacillus
subtilis
Pseudomonas
aeruginosa
243b 500 500 500
243d 250 250 250
243f 125 250 125
243g 500 500 500
243h 125 125 125
160
3.5.2 In vitro antibacterial studies of 1-(N-substituted)-5-(4-Methoxy-phenyl)-1H-
pyrazole derivatives 246 (a-l) and 248 (a-h)
The antibacterial activity of the synthesized compounds was done using Bacillus
subtilis MTCC 441, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC
27853. The above activity was examined qualitatively and quantitatively by the presence
or absence of inhibition zones and zone diameter. Susceptibility of the test organism to
the organic compound was determined by well plate technique.36,37
Each strain was
inoculated in to 10 mL Tryptone Soya Broth (TSB) in 50 mL conical flask, and was
incubated at 37 ºC till they showed good growth. From the well grown flask 60 µl of the
inoculum was spread uniformly on the pre-set media plates. The wells were dug by
sterilized cork borer and organic compound dissolved in DMSO (1 mg/mL and 0.5
mg/mL concentration) were added. Same procedure was repeated for all micro-
organisms, the Petri plates were incubated for 24 h at 37 oC. Here DMSO was used as
negative control and Streptomycin as positive controls. The plates were checked for zone
of inhibition, the compounds which showed good zone inhibition, were studied for MIC.
MIC was performed at different concentration 1, 10, 25, 50, 100, 500 and 1000 µg/mL.
100 µl of the inoculum was uniformly spread onto preset plates and then place sterile
filter paper disks (5mm diameter) on the spread plates. The filter paper disk was loaded
with 5 µl of the sample of different concentration before starting the experiment
aseptically. TSA plates were incubated at 37 ºC for 24 h. The antibacterial screening
revealed that some of the tested compounds showed good inhibition against various tested
microbial strains.
161
Table-3.8: Antibacterial activity of pyrazole esters 246 (a-l)
Organic
compound
Escherichia
coli
Bacillus
subtilis
Pseudomonas
aeruginosa
Concentration
In mg/mL
1 0.5 1 0.5 1 0.5
Streptomycin 17±0.2 15±0.1 20±0.3 17±0.2 16±0.1 13±0.1
Control 00 00 00 00 00 00
246a - - - - - -
246b 10±0.2 07±0.3 12±0.2 10±0.3 11±0.2 08±0.1
246c 06±0.3 03±0.2 07±0.2 05±0.1 06±0.2 04±0.3
246d 13±0.1 10±0.2 12±0.2 10±0.1 14±0.2 12±0.1
246e 10±0.1 07±0.2 09±0.3 07±0.2 09±0.2 08±0.1
246f 14±0.3 12±0.2 13±0.2 11±0.2 14±0.3 11±0.2
246g 08±0.1 06±0.2 07±0.3 05±0.1 08±0.2 05±0.1
246h - - - - - -
246i - - - - - -
246j 11±0.3 09±0.2 10±0.2 08±0.2 11±0.2 08±0.1
246k 06±0.2 04±0.2 05±0.3 03±0.2 05±0.2 03±0.3
246l 10±0.2 08±0.2 08±0.3 06±0.2 09±0.3 06±0.1
Table-3.9: Minimum Inhibitory Concentration (MIC µg/mL) of compounds 246(a-l)
Organic
compound
Escherichia
coli
Bacillus
subtilis
Pseudomonas
aeruginosa
246b 125 125 125
246c 500 500 500
246d 65 125 65
246e 125 250 250
246f 65 65 65
246g 500 500 500
246j 125 125 125
246k 500 500 500
246l 125 500 250
162
Table-3.10: Antibacterial activity of pyrazole carboxamide derivatives 248(a-h)
Organic
compound
Escherichia
coli
Bacillus
subtilis
Pseudomonas
aeruginosa
Concentration
In mg/mL
1 0.5 1 0.5 1 0.5
Streptomycin 17±0.2 15±0.1 20±0.3 17±0.2 16±0.1 13±0.1
Control 00 00 00 00 00 00
248a - - - - - -
248b 11±0.2 08±0.1 10±0.3 07±0.1 12±0.3 09±0.1
248c 08±0.1 06±0.3 09±0.2 07±0.2 09±0.1 06±0.2
248d - - - - - -
248e 06±0.3 04±0.2 07±0.1 05±0.2 07±0.2 04±0.2
248f 10±0.2 08±0.2 11±0.2 08±0.3 11±0.1 09±0.2
248g 09±0.3 07±0.2 08±0.3 05±0.1 08±0.2 06±0.2
248h - - - - - -
Table-3.11: Minimum Inhibitory Concentration (MIC µg/mL) of compounds 248(a-h)
Organic
compound
Escherichia
coli
Bacillus
subtilis
Pseudomonas
aeruginosa
248b 125 125 125
248c 500 250 125
248e 500 500 500
248f 125 125 125
248g 250 500 500
3.6 Conclusions
A new series of novel Ethyl-1-(N-substituted) 5-phenyl-1H-pyrazole-4
carboxylate derivative were synthesized and characterized by IR, 1H-NMR and mass
spectrometry studies. Molecular structure of (241a) and (241j) were also confirmed by
single crystal X-ray analysis. All the synthesized compounds were screened for their
antibacterial activity by MIC method. Among the screened samples, (241d), (241g),
(241l) and (241m) have showed excellent antibacterial activity against all the tested
bacterial strains as compared to the standard drug Ceftriaxone, which is active at 3.125,
163
1.6125, 1.6125, 1.6125 μg/mL against S. aureus, B.subtilis, E.coli, P.aeruginosa strains
respectively.
Interestingly all these active compounds are halogen substituted derivatives,
which is responsible for the enhanced activity. Compound (241f), which is fluorine
substituted compound, has showed significant activity. Compounds (241h) and (241m),
which have quinoline and piperidine substituent respectively, also have showed
significant antibacterial activity against all bacterial strains. All remaining compounds
have exhibited poor antibacterial activity. Pyrazole moiety is one of the active
components present in all molecules, which has showed significant activity in presence of
halogen substituent. Similarly Pyrazole carboxamide derivatives 243 (a-h) were also
employed for antimicrobial study. For this Escherichia Coli, Bacillus subtilis and
Pseudomonas aeruginosa microorganisms were employed. The compound (243f) and
(243h) shows excellent antimicrobial activity against tested strains Escherichia Coli,
Bacillus subtilis and Pseudomonas aeruginosa at concentrations of 1.0 and 0.5 mg/mL
compared to standard drug streptomycin. The compound (243f) and (243h) have
Cyclopentyl and diethyl group. The compound (243d) shows moderate antibacterial
activity against all the tested microbial and which is having cyclohexyl moiety and these
groups enhances the activity of the pyrazole ring. In conclusion, pyrazole moiety is one of
the active components present in the synthesized compounds.
164
NN
O
O
HN
241m
NN
O
O
N
241h
NN
O
O
F
F
F
241d
NN
O
O
Br
241g
Fig. 3.34 Most potent compounds among the synthesized compounds 241(a-n)
N N
N
ONH
N N
N
ONH
N N
N
ONH
243d 243f 243h
Fig. 3.35: Most potent compounds among the synthesized compounds 243 (a-h)
Similarly antimicrobial property of 1-(N-substituted)-5-(4-methoxy-phenyl)-1H-
pyrazole derivatives was determined by well plate method. For this Escherichia Coli,
Bacillus subtilis and Pseudomonas aeruginosa microorganisms were employed.
Antimicrobial study was assessed by MIC plate method. The antibacterial screening
revealed that, few of the tested compounds showed good inhibition against various tested
microbial strains. The compounds (246d) showed significant antibacterial activity
against Escherichia Coli and Pseudomonas aeruginosa at concentrations of 1.0 and 0.5
mg/mL compared to standard drug Streptomycin. The compound (246f) showed similar
165
activity against all the tested bacterial strains as compared with the standard drug. The
remaining compounds showed moderate activity against all of the tested bacterial strains
compared to standard drug Streptomycin. Results of antibacterial studies have been
presented in Table-3.8, 3.9, the compounds (246d) and (246f), which have isopropyl and
cyclohexyl substituent respectively. Similarly pyrazole carboxamide derivatives 246 (a-h)
were also employed for antimicrobial study. For this Escherichia Coli, Bacillus subtilis
and Pseudomonas aeruginosa microorganisms were employed. The compound (248b)
and (248f) shows excellent antimicrobial activity against tested strains Escherichia Coli,
Bacillus subtilis and Pseudomonas aeruginosa at concentrations of 1.0 and 0.5 mg/mL
compared to standard drug Streptomycin. The compound (248b) and (248f) have
morpholine and cyclopentyl group. The compound (248c) shows excellent antibacterial
activity against tested strain Pseudomonas aeruginosa and which is having N-methyl
piperazine moiety and these groups enhances the activity of the pyrazole ring. Results of
antibacterial studies have been presented in Table- 3.10, 3.11.
NN
NH
O
O
248f
NN
N
O
O
O
248b
NN
OO
O
246f
NN
OO
O
246d
Fig. 3.36: Most potent compounds among the synthesized compounds 246 (a-l) and 248
(a-h)
166
It has been observed that, derivatization of the active pyrazole carboxylate into
pyrazole carboxamide leads number of active compounds. Further, the result obtained
clearly indicate that compounds having aliphatic amide linkage are shown pronounced
activity; particularly morpholine and cyclopentyl amide linkage are more active against
all the microbial tested, where as compound bearing aromatic amide linkage is not active.
The result of our present study conferred that the aliphatic amide pharmacophore is
important for antimicrobial activity of pyrazoles. In conclusion, pyrazole moiety is one
of the active components present in the synthesized compounds.
167
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