CHAPTER 3 SYNTHESIS, CHARACTERIZATION AND ...shodhganga.inflibnet.ac.in/bitstream/10603/36693/12/12...Fig. 3.9: Synthesis of some new pyrazolo [3, 4-d] pyrimidine derivatives A simple

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


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).


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


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



+);

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),


+);

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



+);

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



+);

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),


+);

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



+);

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



+);

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



+);

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


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



+);

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)


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),


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)




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




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


: 3065, 2957, 2905 (Ar-H),


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


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



+);

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



+);

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),


+);

1H NMR


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



+);

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


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



+);

1H NMR


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



+);

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



+);

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



+);

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



+);

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



+);

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)


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


: 2936, 2923, 2861, (Ar-H),



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



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)


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



: 2936, 2923, 2861, (Ar-H),



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)


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


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)


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



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


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



: 3065, 2957, 2905 (Ar-H),



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-


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-


O

N

O

NN

O

248b

154

Fig. 3.31: IR Spectrum of {5-(4-methoxy Phenyl)-1-[4-(propan-2-yl) phenyl]-1H-


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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CHAPTER 3 SYNTHESIS, CHARACTERIZATION AND ...shodhganga.inflibnet.ac.in/bitstream/10603/36693/12/12...Fig. 3.9: Synthesis of some new pyrazolo [3, 4-d] pyrimidine derivatives A simple