Design, synthesis and anti-cancer evaluation of a novel series of pyrazolo [1, 5-a] pyrimidine substituted diamide derivatives

MEDICINAL

CHEMISTRY

RESEARCH

Med Chem Res

DOI 10.1007/s00044-016-1770-0

ORIGINAL RESEARCH

Design, synthesis and anti-cancer evaluation of a novel series of

pyrazolo [1, 5-a] pyrimidine substituted diamide derivatives

1 _●

2 _●

1 _●

A.K. Ajeesh Kumar

Yadav D. Bodke Peter Serjious Lakra

1 _●

3

Ganesh Sambasivam Kishore G. Bhat

Received: 4 November 2015 / Accepted: 8 November 2016

©

Springer Science+Business Media New York 2017

Abstract A novel series of pyrazolo [1, 5-a] pyrimidine

substituted diamides has been designed and synthesized

using a linear mode multistep synthesis. The synthesized

Introduction

Pyrazole represent one of the most active classes of com-

pounds possessing a wide range spectrum of biological

activities like potential inhibitors of HIV-1 (Kamal El-Dean

et al. 2009), pesticides (Ge et al. 2006), fungicides (Wu

et al. 2012; Hillebrand et al. 2014; El-Sherief et al. 1997),

analgesic drugs (Nitulescu et al. 2010; Vijesh et al. 2013),

antihypertensive agents (Aly 2006), anticancer activity

(Gouhar et al. 2013; Rashad et al. 2009). Also pyrazole

derivatives are utilized for the synthesis of other fused

heterocyclic systems. Among these, pyrazolo pyrimidines

1

13

compounds were characterized by H NMR, C NMR,

ESI-MS and IR analyses. These new compounds were

screened for their in vitro antiproliferative activity using an

MTT assay. Out of 23 derivatives synthesized in the current

study, compounds 10q, 10u and 10w showed good antic-

ancer activity against HeLa cell line. Furthermore, these

derivatives gave IC₅₀values of less than 10 µM against

HeLa cell and were therefore more potent than the marketed

anticancer drug cis-platin (17.83 µM).

(

Chauhan and Kumar 2013; Bagley et al. 2013) which

●

Keywords Synthesis Buchwald coupling Imine

mimic structurally with biogenic purines (Dinakaran et al.

2012; Yoo et al. 2007; Yuan et al. 2002; Gonclaves et al.

2012) have considerable chemical and pharmacological

importance and are bioisosters to triazolo-thieno pyr-

imidines, imidazoquinazoline (Ley and Thomas 2003;

Hardtmann et al. 1975), pyrimido quinazoline (Nag et al.

●

hydrolysis Pyrazolo [1, 5-a] pyrimidine Anticancer

●

activity MTT Assay

2008) and imidazo-quinolinone (Suzuki et al. 1992).

Moreover, pyrazolo pyrimidines have useful properties as

antimetabolite in purine biochemical reactions. They exhibit

diversiﬁed pharmacological activities like tuberculostatic

Electronic supplementary material The online version of this article

(

doi:10.1007/s00044-016-1770-0 ) contains supplementary material,

(Bakavoli et al. 2010), antimicrobial activities (Curran et al.

which is available to authorized users.

2010), neuroleptic (Kim et al. 2010), central nervous system

depressant (Soliman et al. 2014), antihypertensive (Maeda

et al. 1997; Ali et al. 2010), and antileishmanial (Schenone

et al. 2008).

Our literature survey revealed that most of the active

anticancer related pharmacophores would be fused hetero-

cyclic analogues. In our continuous efforts to identify new

anticancer agents related to fused heterocyclic analogues,

we envisioned the importance of synthesizing their

substituted carboxamides or substituted urea derivatives.

A number of small molecule inhibitors are known in the

*

A.K. Ajeesh Kumar

ajuedat@gmail.com

1

2

Anthem Biosciences Pvt. Ltd. 49, Bommasandra Industrial Area,

Bommasandra, Bangalore 560 099 Karnataka, India

Department of PG Studies and Research in Industrial Chemistry,

School of Chemical Sciences, Kuvempu University,

Shankaraghatta, Shimoga, Karnataka 577 451, India

3

Department of Microbiology, Maratha Mandal’s NGH Institute of

Dental Sciences & Research Centre, Belgaum, Karnataka 590 010,

India

Med Chem Res

Cl

Experimental

Chemistry

Cl

HN

O

N

All chemicals were of analytical grade and obtained from

Sigma–Aldrich Co. The puriﬁcation of all the intermediates

and ﬁnal compounds was carried out by ﬂash column

chromatography using Merck silica gel with 230–400 mesh

size. The purity of the compounds was determined by thin

layer chromatography experiments, performed on alumina-

backed silica gel 40 F254 plates (Merck, Darmstadt, Ger-

many). Thin layer chromatography (TLC) observation of

these plates were carried out by illuminating under UV

N

H

N

O

F

(

254 nm) lamp and suitable stain solutions like KMnO &

4

Fig. 1 Chemical structure of compound 10w, which showed good

antoproliferative activity

Ninhydrin. Melting points were determined using Buchi B-

5

spectra were recorded on Bruker AM-300 (300 MHz for H

NMR and 75 MHz for C NMR) and Bruker AM-400 (400

1

13

40 instrument and are uncorrected. All H and C NMR

1

3

1

13

anticancer studies with the above functional groups.

The best examples are ZM 447439 (Austen et al. 2001),

which contains a carboxamide group and SNS-314 (Oslob

et al. 2008) contains urea link. Based on the above

hypothesis, we made our objective that pyrazolo [1, 5-a]

pyrimidine could be the best fused heterocyclic analogue. In

order to get either a carboxamide or a urea substituted

pharmacophore from pyrazolo [1, 5-a] pyrimidine, we

have to incorporate the synthesis of either an amine or

an acid substitution. The synthesis of these derivatives

includes usage of hazardous materials like hydrazine and

nitro derivatives. In order to avoid these hazardous

materials, we decided to introduce the synthesis of

corresponding bromo substituted pyrazolo [1, 5-a] pyr-

imidine derivative. The introduction of amine group can be

achieved by utilizing corresponding imine counterpart as

surrogatory group; thereby we can avoid the usage of nitro

derivatives.

To fulﬁll the above objectives, we have introduced the

following novel approach. We have synthesized the bromo

derivatives of pyrazolo [1, 5-a] pyrimidine at the respective

positions via the cyclisation approach based on the con-

ventional method reported for nitro derivatives (Gopa-

laswamy et al. 2009). Further, the introduction of amine was

achieved by the acid hydrolysis of their respective imine

counter parts obtained by Buchwald—Hartwig approach

MHz for H NMR and 100 MHz for C NMR), Bruker

BioSpin Corp., Germany. Molecular weights for all the

synthesized compounds were checked by LC–MS

6200 series Agilent Technology. The chemical shifts are

reported in ppm (δ) with reference to TMS as an internal

standard. The signals are designed as follows: s, singlet; d,

doublet; t, triplet; m, multiplet; brs, broad singlet. IR spectra

for all the compounds were recorded using a Bruker Alpha

Fourier transform infrared spectroscopy (FTIR) spectro-

meter using a diamond attenuated total reﬂection (ATR)

single reﬂectance module (24 scans).

General procedure for the synthesis of (E)-1-(substituted-

phenyl)-3-dimethylamino-propenone (2a-c)

Dimethylformamide dimethylacetal (7 vol) was added under

nitrogen atmosphere to corresponding substituted acet-

ophenones (1a-c) (1g) at ambient temperature. The reaction

medium was heated to 110 °C and stirred for 6–8 h. Com-

pletion of the reaction was monitored by TLC. After com-

pletion of the reaction, volatiles were removed under reduced

pressure. The residue obtained was dissolved in ethyl acetate

(2 vol) and hexane (8 vol) was added drop wise to it at room

temperature. The resultant reaction mixture was stirred for 1

h at the same temperature. The solid formed was ﬁltered,

washed with hexane and dried under vacuum.

(

2

Hartwig et al. 1999; Louie and Hartwig 1995; Xin et al.

011) rather than by the conventional nitro to amine

(E)-1-(2-Bromo-5-ﬂuoro-phenyl)-3-dimethylamino-

propenone (2a)

approach (Gopalaswamy et al. 2009). In this communica-

tion, we disclose the novel synthesis of a series of

7

-[(substituted-benzoylamino)-phenyl-pyrazolo [1, 5-a]

This compound was prepared from 2-bromo-5-ﬂuoro acet-

ophenone (1a) (5g, 23.04 mmol) with dimethylformamide

dimethyl acetal (35 mL). It was obtained as pale yellow

solid (5.9 g, 95%). MP: 107.8–108.6 °C. IR (ATR, cm ) υ:

585.78 (C-Br), 1022.41 (C-F), 1068.13 (C-O), 1164.81 (C-

pyrimidine-3-carboxylic acid substituted benzyl amide

derivatives with representative example as shown in Fig. 1,

showing good antiproliferative activity against HeLa

cell line.

−

1

Med Chem Res

N), 1424.39 (C-C), 1456.96 (C-C), 1485.03 (C-C), 1547.82

Procedure for the synthesis of ethyl 5-amino-1H-pyrazole-

4-carboxylate (4)

1

(

C-C), 1639.92 (C=O), 3055.26 (C-H). H NMR (DMSO-

d 300 MHz) δ (ppm): 2.84 (3H, s, –N–CH ), 3.31 (3H, s,

6

,

3

–

N–CH ), 5.16 (1H, d, J = 12.6 Hz, =C–H–CO), 7.15–7.17

To a solution of ethylcyanoacetate (3) (25 g, 221.0 mmol)

in dimethylformamide (25 mL) and acetic acid

(37.5 mL), dimethyl formamide dimethyl acetal

(47.40 g, 397.8 mmol) was added drop wise at room

temperature under nitrogen atmosphere over a period of

30 min. The reaction medium was stirred at room tem-

perature for 2 h. The reaction mixture was cooled to 0 °C

and hydrazine hydrate (80%, 25 mL) was added drop wise

to it over a period of 45 min and then heated to 50 °C for

2 h. Completion of the reaction was monitored by TLC.

After completion of the reaction, the reaction mixture was

diluted with ice cold water (1L) and then extracted to ethyl

acetate (2 × 250 mL). The combined ethyl acetate layer

was dried over anhydrous sodium sulfate, ﬁltered and

evaporated under reduced pressure. The crude material

obtained was puriﬁed by column chromatography over

silica gel, eluted with 2–5% methanol in chloroform to get

the product (4) as off-white solid (24 g, 70%). MP:

3

(

,

2H, m, Ar–H), 7.21 (1H, d, J = 13.0 Hz, =CH–N–(CH ) )

3 2

1

3

7.64 (1H, dt, J = 13.8 Hz, J = 5.1 Hz, Ar–H). C NMR

1

2

(

DMSO-d₆_,100 MHz) δ (ppm): 37.48 (–N–CH ), 45.01

3

(

–N–CH ), 95.1 (–ene–CH), 113.79 & 113.86 (d, J

=

C–F

3

2

7

.8 Hz , ArC–Br), 115.84 & 116.07 (d, J

= 23.2 Hz,

C-F

2

Ar-C), 117.43 & 117.66 (d, J _C_–_F= 22.4 Hz, Ar–C),

3

1

34.99 & 135.07 (d, J

= 8 Hz, Ar–C), 146.6 (Ar–C),

C-F

1

54.8 (–ene–CH), 160.35 & 162.80 (d, J _C_-_F= 244.8 Hz,

ArC–F), 187.8 (–C=O). LC-MS (ESI, m/z): 274.42

[

M+2 H]

(

E)-1-(2-Bromo-phenyl)-3-dimethylamino-propenone (2b)

This compound was prepared from 2’-bromoacetophenone

1b) (5g, 25.12 mmol) with dimethylformamide dimethyl

acetal (35 mL). It was obtained as pale yellow solid (5.9 g,

(

3%). MP: 117.3–118.2 °C. IR (ATR, cm⁻) υ: 585.78

C–Br), 1068.43 (C–O), 1165.12 (C–N), 1425.19 (C–C),

456.66 (C–C), 1485.43 (C–C), 1546.92 (C–C), 1640.21

1

9

(

1

−

1

06.7–108.9 °C. IR (ATR, cm ) υ: 1125.41 (C–O),

337.61 (C–N), 1496.40 (C–C), 1615.86 (N–H bend),

662.37 (ester C=O), 2972.92 (C–H), 3193.79

1

(

C=O), 3057.12 (C–H). H NMR (DMSO-d 300 MHz) δ

ppm): 2.83 (3H, s, –N–CH ), 3.34 (3H, s, –N–CH ), 5.17

1H, d, J = 12.9 Hz, =C–H–CO), 7.21–7.39 (3H, m,

6,

1

(

N–H stretch). H NMR (DMSO-d , 400 MHz) δ (ppm):

6

3

1

.23 (3H, t, J = 7.2 Hz, ester–CH ), 4.16 (2H, q, J = 6.9

3

Hz, ester–CH ), 5.99 (2H, bs, pyrazole–NH ), 7.47 (1H,

2

Ar–H), 7.4 (1H, d, J = 12.1 Hz, =CH–N–(CH ) ), 7.6 (1H,

d, J = 7.8 Hz, Ar–H). C NMR (DMSO-d , 100 MHz) δ

3

2

13

bs, pyrazole–CH), 11.84 (1H, bs, pyrazole–NH).

C

1

3

6

NMR (DMSO-d , 100 MHz) δ (ppm): 14.92 (ester–CH ),

6

3

(ppm): 37.56 (–N–CH₃), 44.84 (–N–CH₃), 95.41

(–ene–CH), 119.56 (Ar–C), 120.63 (Ar–C), 125.38

(ArC–Br), 130.81 (Ar–C), 131.62 (Ar–C), 135.13 (Ar–C),

5

(

9.10 (ester–CH₂), 94.00 (pyrazole–C-3), 139.93

pyrazole–C-4), 151.86 (pyrazole–C-5), 164.27 (carbonyl

from ester). LC-MS (ESI, m/z): 153.7 (M-H) and 156.7

M+H).

1

41.43 (Ar–C-C=O), 153.23 (–ene–CH), 186.48 (C=O).

(

LC-MS (ESI, m/z): 256.4 [M+2H]

(

E)-1-(4-Bromo-phenyl)-3-dimethylamino-propenone (2c)

General procedure for the synthesis of (5 a-c)

This compound was prepared from 4′-bromoacetophenone

1c) (5g, 25.12 mmol) with dimethylformamide dimethyl

acetal (35 mL). It was obtained as pale yellow solid (5.8 g,

To a solution of the enamine compounds (2 a-c) (18.3

mmol) in acetic acid (6 vol), ethyl 5-amino-1H-pyrazole-4-

carboxylate (4) (18.3 mmol) was added lot wise

over a period of 15 min under nitrogen atmosphere. The

reaction mixture was allowed to heat to 110 °C for 6–8 h.

Completion of the reactions was monitored by TLC. After

completion of the reaction, excess amount of acetic acid

was removed under reduced pressure and the residue

obtained was stirred with ice cold water for 30 min.

The precipitated solid was ﬁltered, washed with water and

dried under vacuum. This crude product was further puriﬁed

by column chromatography over silica gel (230–400 mesh

size) eluted with 2–5% of methanol in chloroform. Further,

these compounds were crystallized from appropriate

solvents.

(

₁_%₎_._M_P_:₁₁₃_.₅_–₁₁₄_.₄_°_C_._I_R₍_A_T_R_,_c_m₋1) υ: 580.96 (C-

Br), 1054.05 (C–O), 1112.44 (C–O), 1231.55 (C–N),

411.58 (C–C), 1470.67 (C–C), 1533.69 (C–C), 1574.08

9

1

(

C–C), 1634.29 (C=O), 3051.11 (C–H). H NMR (DMSO-

d , 400 MHz) δ (ppm): 2.92 (3H,s,–N–CH ), 3.15 (3H,s,

6

3

–

N–CH ), 5.81 (1H,d, J = 12 Hz, =C–H–CO), 7.63 (2H, d,

3

2

H, J = 8.4 Hz, Ar–H), 7.73 (1H, d, J = 12 Hz, CH–N–

1

3

(

CH ) , 7.8 (2H, t, J = 6.8 Hz, Ar–H). C NMR (DMSO-

3 2

d , 100 MHz) δ (ppm): 37.65 (N–CH ), 45.04 (N–CH ),

6

3

9

1.05 (–ene–CH), 124.93 (ArC–Br), 129.77 (Ar–C &

Ar–C), 131.59 (Ar–C & Ar–C), 139.74 (Ar–C–C=O),

1

2

55.04 (–ene–CH), 184.85(−C=O). LC–MS (ESI, m/z):

57.0 [M+2 H].

Med Chem Res

7

3

-(2-Bromo-5-ﬂuoro-phenyl)-pyrazolo [1, 5-a] pyrimidine-

-carboxylic acid ethyl ester (5a)

153.55 (pyrazolo pyrimidine junction carbon), 162.15

(−C=O). LC–MS (ESI, m/z): 348.6 [M+2 H]

This compound was obtained by condensation with ethyl 5-

amino-1H-pyrazole-4-carboxylate and (2E)-1-(2-bromo-5-

ﬂuorophenyl)-3-(dimethylamino) prop-2-en-1-one (2a)

under acetic acid heating. It was obtained as pale yellow

7

3

-(4-Bromo-5-ﬂuoro-phenyl)-pyrazolo [1, 5-a] pyrimidine-

-carboxylic acid ethyl ester (5c)

This compound was obtained by condensation with ethyl 5-

amino-1H-pyrazole-4-carboxylate and (2E)-3-(dimethyla-

mino)-1-(4-bromophenyl) prop-2-en-1-one (2c) under acetic

acid heating. It was obtained as pale yellow solid (5.57 g,

−

1

solid (5.7 g, 85%). MP: 196.1–197.4 °C. IR (ATR, cm ) υ:

82.25 (C–Br), 1023.58 (C–F), 1063.45 (C–O), 1168.98

C–O), 1274.44 (C–N), 1460.15 (C–C), 1546.22 (C–C),

5

(

1

−

1

577.30 (C–C), 1700.63 (C=O), 3055.21 (C–H). H NMR

82%). MP: 217.3–218.2 °C. IR (ATR, cm ) υ: 578.63

(

DMSO-d , 400 MHz) δ (ppm): 1.33 (3H, t, J = 7.2 Hz,

6

(C–Br), 1052.34 (C–O), 1122.37 (C–O), 1272.76 (C–N),

1486.07 (C–C), 1545.74 (C–C), 1588.46 (C–C), 1717.55

ester–CH ), 4.44 (2H, q, J = 7.2 Hz, ester–CH ), 7.44 (1H,

3

2

1

d, J = 4.4 Hz, pyrimidine-H), 7.48 (1H, t, J = 8.0 Hz,

Ar–H), 7.68 (1H, dd, J = 3.4 Hz, J = 9.0 Hz, Ar–H), 7.9

(C=O), 3065.08 (C–H). H NMR (DMSO-d ,300 MHz) δ

6

1

2

(ppm): 1.33 (3H, t, J = 7.2 Hz, ester–CH ), 4.33 (2H, q, J

= 6.9 Hz, ester –CH ), 7.51 (1H, d, J = 4.5 Hz, pyrimidine

3

(

1H, dd, J = 5.2 Hz, J = 9.0 Hz, Ar–H), 8.62 (1H, s,

1 2

2

1

3

pyrazole–H), 8.97 (1H, d, J = 4.4 Hz, pyrimidine–H).

C

–

H), 7.84 (2H, d, J = 8.7 Hz, Ar–H), 8.05 (2H, d, J = 8.7

NMR (DMSO-d , 100 MHz) δ (ppm): 14.99 (ester–CH ),

6

3

Hz, Ar-–H), 8.67 (1H, s, pyrazole–H), 8.89 (1H, d, J = 4.5

Hz, pyrimidine–H). C NMR (DMSO-d , 100 MHz) δ

(ppm): 14.93 (ester CH ), 60.09 (ester CH ), 102.54 (pyr-

azole carbon), 110.33 (pyrimidine carbon), 125.55

(ArC–Br), 129.59 (Ar–C), 132.06 (Ar–C), 132.24

(ArC–pyrimidine), 146.29 (pyrazole carbon), 147.37 (pyr-

imidine carbon), 148.65 (pyrimidine C–Ar), 153.49 (pyr-

azolo pyrimidine junction carbon), 162.18 (–C=O).

LC–MS (ESI, m/z): 348.6 [M+2H].

1

3

6

0.02 (ester–CH ), 102.59 (pyrazole carbon), 111.89 (pyr-

2

6

4

imidine carbon), 117.66 & 117.69 (d, J

Br), 119.35 & 119.60 (d, J

= 3 Hz, ArC-

C-F

3

2

= 25 Hz, ArC), 119.85 &

C-F

3

C-F C-F

2

1

20.08 (d, J

= 23 Hz, ArC), 134.00 & 134.09 (d, J

3

=

⁹^H^z^,^A^r^C⁾^,¹³⁵^.⁰⁸^&¹³⁵^.¹⁶⁽^d^,^JC-F = 8 Hz, ArC),

1

45.63 (pyrazole carbon), 147.59 (pyrimidine carbon),

1

47.84 (pyrimidine C-Ar), 153.62 (pyrazolo pyrimidine

1

junction carbon), 160.34 & 162.79 (d, J

= 245 Hz,

C-F

ArC–F), 162.57 (–C = O). LC–MS (ESI, m/z): 367.2

M+2 H].

[

General procedure for the synthesis of (6 a–c)

To a degassed solution of bromo derivatives (5 a–c) (13.7

mmol) in 1, 4-dioxane (10 vol), cesium carbonate (19.2

mmol) was added and argon gas was purged for 10 min.

To the resultant solution, xanthphos (1.23 mmol) and tris

7

-(2-Bromo-phenyl)-pyrazolo [1, 5-a] pyrimidine-3-

carboxylic acid ethyl ester (5b)

This compound was obtained by condensation with ethyl 5-

amino-1H-pyrazole-4-carboxylate and (2E)-3-(dimethyla-

mino)-1-(2-bromophenyl) prop-2-en-1-one (2b) under

acetic acid heating. It was obtained as pale yellow solid (5.6

g, 83%). MP: 208.9–209.8 °C. IR (ATR, cm⁻) υ: 585.15

(dibenzylidine acetone) dipalladium (0.41 mmol) were

charged and continued the argon gas purging for 5 min.

Bezophenonimine (20.5 mmol) was added drop wise

and the argon purging was continued for another 10 min.

The reaction mixture was allowed to reﬂux at 110 °C

for 4–6 h under argon atmosphere. Completion of the

reaction was monitored by TLC. The reaction medium

was ﬁltered through celite bed, washed with ethyl

acetate (10 vol) and the ﬁltrate was concentrated

under reduced pressure. The crude material was further

puriﬁed by column chromatography over silica gel

1

(

1

C–Br), 1172.97 (C–O), 1232.19 (C–O), 1260.08 (C–N),

486.02 (C–C), 1549.74 (C–C), 1589.24 (C–C), 1694.60

1

(

C=O), 3072.94 (C–H). H NMR (DMSO-d , 400 MHz) δ

ppm): 1.33 (3H, t, J = 7.2 Hz, ester–CH ), 4.33 (2H, q, J

6

3

=

6.8 Hz, ester-CH₂), 7.41 (1H, d, J = 4.4 Hz,

pyrimidine–H), 7.62 (2H, ddd, J = 2.8 Hz, J = 3.2 Hz, J

=

Hz, Ar–H), 7.88 (1H, dd, J = 4 Hz, J = 5.2 Hz, Ar–H),

1

2

3

6 Hz, Ar–H & Ar–H), 7.67(1H, dd, J = 3.2 Hz, J = 6

1 2

(230–400 mesh size) and eluted with 40–60% of ethyl

1

2

acetate in hexane.

8

.62 (1H, s, pyrazole–H), 8.96 (1H, d, J = 4.4 Hz,

1

3

pyrimidine–H). C NMR (DMSO-d , 100 MHz) δ (ppm):

6

1

4.93 (ester–CH ), 60.13 (ester–CH ), 102.72 (pyrazole

7-[2-(Benzhydrylidene-amino)-5-ﬂuoro-phenyl]-pyrazolo

[1, 5-a] pyrimidine-3-carboxylic acid ethyl ester (6a)

3

2

carbon), 111.79 (pyrimidine carbon), 122.70 (ArC-Br),

1

28.48 (ArC), 132.03 (ArC), 132.49 (ArC), 132.80 (ArC),

33.17 (ArC–pyrimidine), 146.89 (pyrazole carbon),

47.47 (pyrimidine carbon), 147.89 (pyrimidine C–Ar),

It was obtained as pale yellow solid (5.14 g, 81%). MP:

210.3–211.4 °C. IR (ATR, cm ) υ: 1049.19 (C–F),

−1

Med Chem Res

1

(

1

099.62 (C–O), 1193.72 (C–O), 1269.64 (C–N), 1407.46

C–C), 1444.28 (C–C), 1479.07 (C–C), 1537.34 (C–C),

573.30 (C–C), 1609.84 (C=O), 1683.25 (N=imine), 3054

7-[4-(Benzhydrylidene-amino)-phenyl]-pyrazolo [1, 5-a]

pyrimidine-3-carboxylic acid ethyl ester (6c)

1

(

C–H). H NMR (DMSO-d , 400 MHz) δ (ppm): 1.3

It was obtained as pale yellow solid (5.28 g, 82%). MP:

6

−

1

(

3H,t, J = 7.2 Hz, ester –CH ), 4.29 (2H, q, J = 7.2 Hz,

222.1–223.0 °C. IR (ATR, cm ) υ: 1046.98 (C–O),

1177.30 (C–O), 1265.71 (C–N), 1402.67 (C–C), 1443.71

(C–C), 1494.89 (C–C), 1538.61 (C–C), 1597.50 (C–C),

3

ester–CH ), 6.87 (1H, dd, J = 5.2 Hz, J = 8.8 Hz, Ar–H),

2

1

2

6

.95 (2H, d, J = 7.2 Hz, pyrimidine–H), 7.21–7.29 (4H, m,

Ar–H), 7.31–7.36 (5H, m, Ar–H), 7.43–7.50 (2H,m, Ar–H),

.55 (1H,s, pyra zole–H), 8.8 (1H, d, J = 4.6 Hz,

1

1612.01 (C=O), 1683.64 (N=, imine), 3043.00 (C–H). H

8

NMR (DMSO-d , 400 MHz) δ (ppm): 1.32 (3H, t, J = 7.2

6

1

3

pyrimidine–H). C NMR (DMSO-d , 100 MHz) δ (ppm):

Hz, ester–CH ), 4.28 (2H, q, J = 7.2 Hz, ester –O–CH ),

6

3

2

1

4.96 (ester CH ), 60.04 (ester CH ), 102.33 (pyrazole

6.95 (2H, d, J = 8.4 Hz, Ar–H), 7.25 (2H,d, J = 7.2 Hz,

Ar–H), 7.39 (3H, dd, J = 8.0 Hz, J = 12.0 Hz, Ar–H),

3

2

carbon), 112.01 (pyrimidine carbon), 117.42

1

=

1

ArC), 128.75 (ArC & ArC), 129.04 ( ArC & ArC), 129.22 (

ArC & ArC), 129.63 (ArC), 131.64 (ArC), 135.39 (ArC– to

imine), 138.74 (ArC– to imine), 145.57 & 145.58

&

1

2

17.66 (d, J

= 24 Hz, ArC), 118.21 & 118.43 (d, J

7.43 (1H, d, J = 4.8 Hz, pyrimidine–H), 7.49 (2H, dd, J =

C-F

1

3

22 Hz, ArC), 123.67 & 123.73 (d, J

23.75 & 123.81(d, J

= 8 Hz, ArC),

= 8Hz, ArC), 128.59 (ArC &

8.0 Hz, J = 12.0 Hz, Ar–H), 7.57 (1H, dd, J = 8.0 Hz, J

C-F

2

1

2

3

= 12.0 Hz, Ar–H), 7.34 (2H, d, J = 7.2 Hz, Ar–H), 8.04

(2H, d, J = 8.4 Hz, Ar–H), 8.64 (1H, s, pyrazole–H), 8.80

C-F

1

3

(1H, d, J = 4.4 Hz, pyrimidine–H). C NMR (DMSO-d₆,

100 MHz) δ (ppm): 14.90 (ester CH ), 59.99 (ester CH ),

3

2

4

(

d, J

= 1Hz, pyrimidine C-Ar), 146. 14 & 146.17 (d, J

102.21 (pyrazole carbon), 111.91 (pyrimidine carbon),

122.87 (Ar–C), 123.34 (Ar–C),128.49 (Ar–C & Ar–C),

128.71 (Ar–C & Ar–C), 130.85 (Ar–C & Ar–C), 132.89

(Ar–C & Ar–C), 133.12 (Ar–C), 135.49 (Ar–C), 138.67

(Ar–C to pyrimidine), 147.01 (Ar–C to imine N), 147.08

(pyrazole carbon), 148.17 (pyrimidine carbon), 149.56

C-F

=

3Hz,

ArC),

147.10

(pyrazole–C),

148.08

C-F

(

pyrimidine–C), 152.84 (pyrazolo pyrimidine junction car-

1

bon), 157.15 & 159.54 (d, J

= 239 Hz, ArC–F), 162.16

C-F

(

+

−C=O), 168.89 (imine–C). LC–MS (ESI, m/z): 465.2 [M

H].

(pyrazolo pyrimidine junction carbon), 153.49 (pyrazolo

pyrimidine junction carbon), 163.12 (−C=O), 168.08

(imine–C). LC–MS (ESI, m/z): 446.8 [M+H].

7

-[2-(Benzhydrylidene-amino)-phenyl]-pyrazolo [1, 5-a]

pyrimidine-3-carboxylic acid ethyl ester (6b)

General procedure for the synthesis of (7a–c)

It was obtained as pale yellow solid (5.15 g, 80%). MP:

1

2

1

(

1

3

1

16.3–217.5 °C. IR (ATR, cm⁻) υ: 1117.42 (C–O),

To a suspension of the imine derivative (6a–c) (9.68 mmol)

in ethanol (10 vol), hydrochloric acid (6N, 4 vol) was added

drop wise at 0 °C over a period of 15 min under nitrogen

atmosphere. The resultant reaction medium was allowed to

stir at ambient temperature for a period of 1–2 h. Comple-

tion of the reaction was monitored by TLC. After comple-

tion of the reaction, the reaction medium was concentrated

under reduced pressure to remove ethanol from the medium

and the residue was extracted to methyl tertiary butyl ether

(2 × 75 mL). The aqueous layer was basiﬁed using potas-

sium carbonate to attain the pH above 12 and then extracted

to ethyl acetate (2 × 75 mL). The organic layer was dried

over sodium sulphate, ﬁltered and concentrated to get the

crude product as pale yellow solid. The required amine

products (7a–c) were recrystallized further from the

appropriate solvents.

175.57 (C–O), 1227.15 (C–N), 1269.03 (C–N), 1403.54

C–C), 1442.23 (C–C), 1485.64 (C–C), 1485.64 (C–C),

539.06 (C–C), 1614.23 (C=O), 1681.96 (N=imine),

056.49 (C–H). H NMR (DMSO-d , 300 MHz) δ (ppm):

.3 (3H, t, J = 6.9 Hz, ester–CH ), 4.29 (2H, q, J = 7.2 Hz,

ester–CH ), 6.87 (1H, d, J = 3Hz, Ar-H), 6.93 (2H, d, J =

.2 Hz, Ar–H), 7.12 (1H, d, J = 4.2Hz, pyrimidine–H),

.16–7.19 (3H, m, Ar–H), 7.33–7.36 (5H, m, Ar–H),

.439–7.41 (2H, m, Ar–H), 7.53–7.55 (1H, m, Ar–H),

.53 (1H, s, pyrazole–H), 8.77 (1H, d, J = 4.5 Hz,

pyrimidine–H). C NMR (DMSO-d , 100 MHz) δ (ppm):

4.89 (ester CH ), 60.00 (ester CH ), 102.19 (pyrazole

3 2

carbon), 111.91 (pyrimidine carbon), 121.90 (Ar–C),

22.41 (ArC), 123.81(Ar–C), 128.49 (Ar–C & Ar–C),

28.71 (Ar–C & Ar–C), 129.05 (Ar–C & Ar–C), 129.21

1

6

3

2

7

8

1

3

6

1

(

Ar–C & Ar–C), 129.53 (Ar–C), 130.85 (Ar–C), 131.30

Ar–C), 131.53 (Ar–C), 135.49 (Ar–C), 138.85 (Ar–C to

7-(2-Amino-5-ﬂuoro-phenyl)-pyrazolo [1, 5-a] pyrimidine-

3-carboxylic acid ethyl ester (7a)

pyrimidine), 147.03 (Ar–C to imine N), 147.07

pyrazole–C), 148.13 (pyrimidine–C), 149.56 (pyrimidine

C-Ar), 152.77 (pyrazolo pyrimidine junction carbon),

(

It was obtained as pale yellow solid (2.4 g, 83%). MP:

−1

1

4

62.21 (−C=O), 168.10 (imine–C). LC–MS (ESI, m/z):

47.5 [M+H].

181.2–182.1 °C. IR (ATR, cm ) υ: 1039.63 (C–F),

1084.39 (C–O), 1119.25 (C–O), 1330.21 (C–N), 1402.71

Med Chem Res

(

1

(

C–C), 1431.37 (C–C), 1492.93 (C–C), 1545.42 (C–C),

607.21 (C=O), 3086.02 (C–H), 3384.0 (N–H). H NMR

Hz, Ar–H), 7.38 (1H, d, J = 4.8 Hz, pyrimidine –H), 8.05

(2H, d, J = 8.8 Hz, Ar–H), 8.64 (1H, s, pyrazole–H), 8.71

1

3

DMSO-d , 400 MHz) δ (ppm): 1.32 (3H,t, J = 7.1 Hz,

(1H, d, J = 4.8 Hz, pyrimidine –H). C NMR (DMSO-d₆,

100 MHz) δ (ppm): 14.93 (ester CH ), 59.98 (ester CH ),

6

ester–CH ), 4.32 (2H, q, J = 7.2 Hz, ester –O–CH ), 5.13

3

2

3

2

(

2H, bs, –NH ), 6.81 (1H, dd, J = 5.2 Hz, J = 9.5 Hz,

101.92 (pyrazole carbon), 108.73 (pyrimidine carbon),

117.84 (Ar–C & Ar–C), 125.88 (Ar–C), 130.18 (Ar–C &

Ar–C), 131.90 (Ar–C to pyrimidine ring), 145.65 (pyrazole

carbon), 147.18 (amine substituted carbon), 148.91 (pyr-

imidine C-Ar), 152.92 (pyrazolo pyrimidine junction car-

bon), 162.27 (−C=O). LC–MS (ESI, m/z): 282.3 [M+H].

2

1

2

Ar–H), 7.11–7.18 (2H, m, Ar–H), 7.32 (1H, d, J = 4.4 Hz,

pyrimidine–H), 8.59 (1H, s, pyrazole–H), 8.83 (1H, d, J =

4

1

3

.4 Hz, pyrimidine–H). C NMR (DMSO-d , 100 MHz) δ

6

(

ppm): 14.97 (ester CH ), 59.94 (ester CH ), 102.49 (pyr-

3 2

azole carbon), 112.04 (pyrimidine carbon), 114.96 &

1

=

1

3

2

15.04 (d, J

= 8 Hz, ArC), 116.78 & 117.01 (d, J

C-F

3

23 Hz, ArC), 117.38 & 117.46 (d, J

18.76 & 118.98 (d, J

= 8 Hz, ArC),

= 22 Hz, ArC), 144.28 (pyrazole

General procedure for the synthesis of 7-[aryl

(benzoylamino)-phenyl]-pyrazolo [1, 5-a] pyrimidine-3-

carboxylic acid ethyl ester (8 a-h)

C-F

2

C-F

4

carbon), 146.21 & 146.23 (d, J

= 2 Hz, ArC), 147.30

C-F

(

pyrimidine carbon), 148.59 (pyrimidine C–Ar), 153.17

pyrazolo pyrimidine junction carbon), 152.69 & 154.99 (d,

To a solution of the amine (7a–c) (2.49 mmol) in dime-

thylacetamide (5 vol), the corresponding acid chloride (2.49

mmol) was added drop wise at 0 °C under argon atmosphere

and then slowly warmed the reaction medium to room

temperature. The reaction medium was stirred at the same

temperature for 1 h. The reaction conversion was monitored

by TLC. The reaction mixture was poured to ice cold water

and stirred at room temperature for 30 min and the pre-

cipitated solid was ﬁltered, washed with water, and dried

under vacuum. This crude product was further puriﬁed by

column chromatography using ethyl acetate and hexane to

get the required amide.

1

J _C_-_F= 300 Hz, ArC –F), 162.33 (−C=O). LC–MS (ESI,

m/z): 300.7 [M+H].

7

-(2-Amino-phenyl)-pyrazolo [1, 5-a] pyrimidine-3-

carboxylic acid methyl ester (7b)

It was obtained as pale yellow solid (2.52 g, 80%). MP:

1

(

−

1

88.0–189.1 °C. IR (ATR, cm ) υ: 1085.12 (C–O),

118.43(C–O), 1329.42 (C–N), 1412.52 (C–C), 1428.45

C–C), 1490.49 (C–C), 1544.43 (C–C), 1608.32 (C=O),

1

3

079.22 (C–H), 3382.73 (N–H). H NMR (DMSO-d 400

6,

MHz) δ (ppm): 1.3 (3H, t, J = 7.1 Hz, ester–CH ), 4.28

3

(

2H, q, J = 7.2 Hz, ester–O–CH ), 5.18 (2H, bs, –NH ),

7-[5-Fluoro-2-(3-triﬂuoromethyl-benzoylamino)-phenyl]-

pyrazolo [1, 5-a] pyrimidine-3-carboxylic acid ethyl ester

(8a)

2

6

.62 (1H, ddd, J = 0.8 Hz, J = 6.4 Hz, J = 6.8 Hz,

1 2 3

Ar–H), 6.77 (1H, dd, J = 0.8 Hz, J = 7.6 Hz, Ar–H), 7.20

2

(

2H, dq, J = 5.2Hz, J = 7.6 Hz, Ar–H), 7.23 (1H, d, J =

1 2

4

.4 Hz, pyrimidine–H), 8.54 (1H, s, pyrazole –H), 8.78 (1H,

It was obtained as pale yellow solid (0.94 g, 80%). MP:

188.1–189.2 °C. IR (ATR, cm ) υ: 1047.53 (C–F),

1

3

−1

d, J = 4.4 Hz, pyrimidine –H). C NMR (DMSO-d , 100

6

MHz) δ(ppm): 14.97 (ester CH ), 59.90 (ester CH ), 102.34

1070.48 (C–F), 1129.03 (C–F), 1165.39 (C–F), 1200.04

(C–O), 1330.90 (C–N), 1418.10 (C–C), 1482.06 (C–C),

1523.00 (C–C), 1550.95 (C–C), 1618.12 (C=O), 1667.94

3

2

(

pyrazole carbon), 111.90 (pyri midine carbon), 114.99

Ar–C), 115.92 (Ar–C), 116.18 (Ar–C), 131.07 (Ar–C),

1

31.77 (Ar–C to pyrimidine ring), 147.24 (pyrazole car-

(C=O), 3069.90 (C-H), 3313.13 (C-N); H NMR (DMSO-

bon), 147.51 (pyrimidine carbon), 147.82 (amine sub-

d , 400 MHz) δ(ppm) : 1.31 (3H, t, J = 7.1 Hz, ester –CH ),

6

3

stituted carbon), 148.61 (pyrimidine C–Ar), 153.09

4.29 (2H, q, J = 7.2 Hz, ester–O–CH ), 7.38 (1H, d, J =

2

(

pyrazolo pyrimidine junction carbon), 162.36 (−C=O).

4.0 Hz, pyrimidine –H), 7.57 (1H, dt, J = 4.0 Hz, J = 8.0

1

2

LC–MS (ESI, m/z): 283.4 [M+H].

Hz, Ar–H), 7.64–7.71 (2H, m, Ar–H), 7.76–7.80 (2H, m,

Ar–H), 7.85(2H, td, J = 4.3 Hz, J = 8.5 Hz, Ar–H), 8.61

1

2

7

3

-(4-Amino-5-ﬂuoro-phenyl)-pyrazolo [1, 5-a] pyrimidine-

-carboxylic acid ethyl ester (7c)

(1H, s, pyrazole–H), 8.81 (1H, d, J = 4.0 Hz,

pyrimidine–H), 10.36 (1H, bs, amide–NH). C NMR

1

3

(

DMSO-d , 100 MHz) δ (ppm): 14.92 (ester CH ), 59.96

6

3

It was obtained as pale yellow solid (2.58 g, 82%). MP:

1

(ester CH ), 102.17 (pyrazole carbon), 111.61 (pyrimidine

2

91.4–192.3 °C. IR (ATR, cm⁻¹) υ: 11250.30 (C–O),

183.61 (C–O), 1234.31 (C–N), 1273.83 (C–N), 1504.76

carbon), 118.10 & 118.35 (d, J = 25 Hz, ArC), 118.50 &

2

CF

2

118.72 (d, J = 22 Hz, ArC), 120.20, 122.91, 125.62 &

CF

1

(

3

1

C–C) 1537.03 (C–C), 1602.47 (C=O), 3043.01 (C–H),

128.33 (q, J = 271 Hz, Ar–CF ), 124.39, 124.43, 124.47

CF

3

1

3

338.56 (N–H). H NMR (DMSO-d , 400 MHz) δ (ppm):

& 124.51 (q, J = 4 Hz, ArC), 127.56 & 127.64 (d, J

= 8Hz, ArC), 128.62, 128.65, 128.68 & 128.71 (q, J

3 Hz, ArC), 128.78 & 128.86 (d, J_C_F= 8 Hz, ArC),

6

CF

3

.32 (3H, t, J = 6.8 Hz, ester –CH ), 4.3 (2H, q, J = 7.2 Hz,

=

3

CF

3

ester –O–CH ), 6.06 (2H, bs, –NH ), 6.72 (2H, d, J = 8.8

2

Med Chem Res

2

1

29.02, 129.34, 129.66 & 129.98 (q, J = 32 Hz, Ar-C),

7.68–7.75 (2H, m, Ar–H), 8.62 (1H, s, pyrazole–H), 8.83

CF

30.14 (Ar–C), 132.10 (Ar–C), 132. 99, 133.02, 133.05 &

33.08 (q, J = 3 Hz), 135.52 (pyrazole carbon), 145.38

145.39 (d, J = 1Hz, Ar–C), 147.21 (pyrimidine car-

bon), 148.43 (pyrimidine C–Ar), 153.21 (pyrazolo pyr-

(1H, d, J = 4.0 Hz, pyrimidine–H), 10.28 (1H, s,

4

13

amide–NH). C NMR (DMSO-d , 75 MHz) δ (ppm): 14.90

CF

4

6

&

(ester CH ), 59.92 (ester CH ), 102.14 (pyrazole carbon),

CF

3

2

107.38, 107.64 & 107.89 (t, J = 25.5 Hz, Ar-C), 111.27

& 111.46 (d, J = 18 Hz, ArH), 111.34 & 111.53 (d, J

CF CF

CF

1

2

imidine junction carbon), 158.31 & 160.73 (d, J = 242

CF

Hz, ArC–F), 162.62 (amide –C=O), 164.77 (ester –C=O).

LC–MS (ESI, m/z): 473.3 [M+H].

= 19 Hz, ArC), 111.45 (pyrimidine carbon), 118.13 &

2

118.37 (d, J = 24 Hz, Ar–C), 118.53 & 118.75 (d, J

CF

3

=

24 Hz, Ar–C), 127.56 & 127.64 (d, J = 8 Hz, Ar–C),

CF

3

7

-[2-(3, 4-Dichloro-benzoylamino)-5-Fluoro-phenyl]-

pyrazolo [1, 5-a] pyrimidine-3-carboxylic acid ethyl ester

8b)

128.87 & 128.95 (d, J = 8 Hz, Ar–C), 132.73 & 132.75

CF

4

3

(d, J = 2 Hz), 137.86, 137.95 & 138.04 (t, J = 9 Hz,

CF

(

Ar–C), 145.22 (pyrazole carbon), 147.21 (pyrimidine car-

bon), 148.45 (pyrimidine C–Ar), 153.22 (pyrazolo pyr-

1

It was obtained as pale yellow solid (0.96 g, 82%). MP:

1

(

1

imidine junction carbon), 158.35 & 160.77 (d, J = 242

CF

98.3–199.2 °C. IR (ATR, cm⁻) υ: 754.71 (C–Cl), 786.52

C–Cl), 1094.84 (C–F), 1162.17 (C–O), 1198.87 (C–O),

297.04 (C–N), 1411.17 (C–C), 1513.59 (C–C), 1544.17

C–C), 1677.65 (C=O), 1707.16 (C=O), 3062.83 (C–H),

1

Hz, Ar–C–F), 161.21 & 163.64 (d, J = 243 Hz, ArC–F),

161.34 & 163.80 (d, J_C_F= 246 Hz, Ar–C–F), 162.66

(amide –C=O), 163.67 (ester –C=O). LC–MS (ESI, m/z):

441.2 [M+H].

1

CF

1

(

3

1

259.52 (N–H); H NMR (DMSO-d , 400 MHz) δ (ppm):

6

.32 (3H, t, J = 7.1 Hz, ester –CH ), 4.30 (2H, q, J = 7.2

7-[2-(3, 4-Dichloro-benzoylamino)-phenyl]-pyrazolo [1, 5-

3

Hz, ester–O–CH ), 7.35 (1H, d, J = 4.0 Hz, pyrimidine–H),

a] pyrimidine-3-carboxylic acid ethyl ester (8d)

2

7

(

.53–7.59 (2H, m, Ar–H), 7.67–7.76 (4H, m, Ar–H), 8.61

1H, s, pyrazole–H), 8.81(1H, d, J = 4.0 Hz,

pyrimidine–H), 10.29 (1H, s, amide –NH–). C NMR

It was obtained as pale yellow solid (1.42 g, 80%). MP:

1

3

−1

218.7–219.6 °C. IR (ATR, cm ) υ: 748.69 (C–Cl), 782.37

(

DMSO-d , 75 MHz) δ (ppm): 14.90 (ester CH ), 59.92

(C–Cl), 1087.11 (C–O), 1137.55 (C–O), 1232.13 (C–N),

1271.53 (C–N), 1441.34 (C–C), 1480.95 (C–C), 1529.46

6

3

ester CH ), 102.13 (pyrazole carbon), 111.45 (pyrimidine

2

carbon), 117.99 & 118.32 (d, J = 24.6 Hz, Ar-C), 118.40

(C–C), 1583.37 (C–C), 1684.93 (C=O), 1719.08 (C=O),

CF

2

1

&

118.70 (d, J = 22.12 Hz, Ar–C), 127.42 & 127.53 (d,

3086.53 (C–H), 3331.15 (N–H). H NMR (DMSO-d , 400

CF

6

3

J_C_F= 8.85 Hz, Ar–C), 128.21 (Ar–C), 128.74 & 128.85

MHz) δ (ppm): 1.3 (3H, t, J = 7.2 Hz, ester –CH ), 4.31

3

(

d, J = 8.4Hz, Ar–C), 129.84 (Ar–C), 131.13 (Ar–C),

(2H, q, J = 7.2 Hz, ester –O–CH ), 7.33 (1H, d, J = 4.4 Hz,

CF

2

4

1

31.59 (Ar–C), 132.83 & 132.86 (d, J_C_F= 2.55 Hz,

pyrimidine–H), 7.44–7.48 (1H, m, Ar–H), 7.59 (d, 1H, J₁

Ar–C), 134.80 (ArC–Cl), 134.90 (ArC–Cl), 135.68 (pyr-

= 2.0 Hz, J = 6.4 Hz, Ar–H), 7.64–7.77 (5H, m, Ar–H),

2

azole carbon), 147.01 (pyrimidine carbon), 148.40 (pyr-

8.56 (1H, s, pyrazole–H), 8.81 (1H, d, J = 4.4 Hz,

pyrimidine–H), 10.28 (1H, bs, amide–NH). C NMR

1

3

imidine C–Ar), 153.14 (pyrazolo pyrimidine junction

1

carbon), 157.84 & 161.07 (d, J = 241.95 Hz), 162.59

(DMSO-d , 75 MHz) δ (ppm): 14.85 (ester CH ), 59.89

CF

6

3

(

amide –C=O), 163.85 (ester –C=O). LC–MS (ESI, m/z):

(ester CH ), 102.23 (pyrazole carbon), 111.45 (pyrimidine

2

4

74.2 [M+H].

carbon), 125.71 (Ar–C), 125.91 (Ar–C), 126.31 (Ar–C),

128.22 (Ar–C), 129.82 (Ar–C), 131.07 (Ar–C), 131.52

7

-[2-(3, 5-Diﬂuoro-benzoylamino)-5-Fluoro-phenyl]-

(Ar–C), 134.79 (ArC–Cl), 134.98 (ArC–Cl), 136.43

(Ar–C), 146.76 (pyrazole carbon), 147.05 (pyrimidine car-

bon), 148.43 (pyrimidine C–Ar), 153.06 (pyrazolo pyr-

imidine junction carbon), 162.14 (amide –C=O), 163.73

(ester –C=O). LC–MS (ESI, m/z): 455.4 [M+H].

pyrazolo [1, 5-a] pyrimidine-3-carboxylic acid ethyl ester

8c)

(

It was obtained as pale yellow solid (0.89 g, 81%). MP:

2

1

06.6–207.7 °C. IR (ATR, cm⁻¹) υ: 1093.65 (C–F),

169.92 (C–F), 1200.00 (C–F), 1239.92 (C–o), 1271.77

7-[2-(3, 5-Diﬂuoro-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acid ethyl ester (8e)

(

C–O), 1314.62 (C–N), 1408.85 (C–C), 1435.06 (C–C),

1

548.67 (C–C), 1593.81 (C–C), 1618.10 (C=O), 1667.62

1

(

C=O), 3019.19 (C–H), 3297.84 (N–H); H NMR (DMSO-

It was obtained as pale yellow solid (1.3 g, 79%). MP:

−1

d , 400 MHz) δ(ppm) : 1.32 (3H, t, J = 7.1 Hz, ester–CH ),

202.4–203.3 °C. IR (ATR, cm ) υ: 1054.69 (C–F),

1099.29 (C–F), 1132.50 (C–O), 1171.59 (C–O), 1234.24

(C–N), 1271.59 (C–O), 1444.17 (C–C), 1481.63 (C–C),

6

3

4

.30 (2H, q, J = 7.2 Hz, ester–O–CH ), 7.29 (2H, dd, J =

2 1

2

Hz, J = 6.0 Hz, Ar–H), 7.35 (1H, d, J = 4.0 Hz,

2

pyrimidine–H), 7.47 (1H, dt, J = 4.0 Hz, J = 8.0 Hz,

1522.82 (C–C), 1675.73 (C=O), 1717.82 (C=O), 3070.94

1

2

1

Ar–H), 7.56 (1H, dt, J = 4.0 Hz, J = 8.0 Hz, Ar–H),

(C–H), 3260.46 (N–H). H NMR (DMSO-d , 400 MHz) δ

1

2

6

Med Chem Res

(

6

ppm): 1.3 (3H, t, J = 7.2 Hz, ester –CH ), 4.30 (2H, q, J =

1126.86 (C–O), 1185.61 (C–O), 1230.50 (C–N), 1269.80

(C–N), 1410.14 (C–C), 1514.14(C–C), 1544.90(C–C),

3

.8Hz, ester –O–CH ), 7.27 (2H, dd, J = 2.4 Hz, J = 5.6

2 1 2

Hz, Ar–H), 7.33 (1H, d, J = 4.4 Hz, pyrimidine–H),

1601.21 (C=O), 1671.08 (C=O), 3068.08 (C–H), 3390.87

1

7

.43–7.49 (2H, m, Ar–H), 7.65–7.69 (1H, m, Ar–H),

(N–H). H NMR (DMSO-d , 400 MHz) δ (ppm): 1.32 (3H,

6

7

.72–7.78 (2H, m, Ar–H), 8.58 (1H, s, pyrazole–H), 8.81

t, J = 8.0 Hz, ester–CH ), 2.37 (6H, s, Ar–CH & Ar–CH

3

(

1H, d, J = 4.4 Hz, pyrimidine–H), 10.27 (1H, bs,

), 4.31 (2H, q, J = 8.0 Hz, ester –O–CH ), 7.25 (1H, s,

Ar–H), 7.50 (1H, d, J = 4.0 Hz, pyrimidine–H), 7.59 (2H, s,

Ar–H & Ar–H), 8.02 (2H, d, J = 12.0 Hz, Ar–H), 8.19 (2H,

2

1

3

amide–NH). C NMR (DMSO-d , 75 MHz) δ (ppm): 14.83

6

(

ester CH ), 59.89 (ester CH ), 102.21 (pyrazole carbon),

3 2

2

1

07.11, 107.45 & 107.79 (t, J = 25.5 Hz, Ar-C), 111.15,

d, J = 8.0 Hz, Ar–H), 8.68 (1H, s, pyrazole–H), 8.85 (1H, d,

CF

2

13

11.32 & 111.49 (t, J = 12.75 Hz, ArH & ArH), 111.49

J = 4.0 Hz, pyrimidine–H), 10.52 (1H,s, amide–NH).

C

CF

(

pyrimidine carbon), 125.80 (Ar–C), 126.01 (Ar–C), 126.41

NMR (DMSO-d₆_,75 MHz) δ: 14.87 (ester–CH ), 21.26

3

(

1

Ar–C), 131.49 (Ar–C), 131.55 (Ar–C), 136.27 (Ar–C),

(Ar–CH & Ar–CH ), 59.95 (ester–CH ), 102.20 (pyrazole

3

2

3

37.98, 138.09 & 138.21 (t, J = 9Hz, Ar–C), 146.68

carbon), 109.58 (pyrimidine carbon), 119.97 (ArC & ArC),

124.85 (ArC), 125.88 (ArC & ArC), 130.93 (ArC & ArC),

133.55 (ArC), 135.03 (ArC), 138.05 (ArC–Me & ArC–Me),

142.64 (pyrazole carbon), 146.94 (ArC–NH), 147.28 (pyr-

imidine carbon), 148.81 (pyrimidine C–Ar), 153.22 (pyr-

azolo pyrimidine junction carbon), 162.18 (amide –C=O),

166.59 (acid −C=O). LC–MS (ESI, m/z): 415.3 [M+H].

CF

(

pyrazole carbon), 147.04 (pyrimidine carbon), 148.44

pyrimidine C–Ar), 153.06 (pyrazolo pyrimidine junction

1

carbon), 162.16 (amide –C=O), 160.70 & 163.98 (d, J

=

CF

1

246 Hz, ArC–F), 160.86 & 164.14 (d, J = 246 Hz,

CF

ArC–F), 163.45 (ester –C=O). LC–MS (ESI, m/z): 423.4

M+H].

[

7

-[4-(3, 4-Dichloro-benzoylamino)-phenyl]-pyrazolo [1, 5-

7-[4-(2, 4, 6-Trichloro-benzoylamino)-phenyl]-pyrazolo [1,

a] pyrimidine-3-carboxylic acid ethyl ester (8f)

5-a] pyrimidine-3-carboxylic acid ethyl ester (8h)

It was obtained as pale yellow solid (0.97 g, 81%). MP:

2

It was obtained as pale yellow solid (1.0 g, 78%). MP:

220.3–221.4 °C. IR (ATR, cm ) υ: 626.21 (C–Cl), 690.61

55.4–256.6 °C. IR (ATR, cm⁻) υ: 741.97 (C–Cl), 773.19

1

−1

(

1

(

1

C–Cl), 1049.81 (C–O), 1128.12 (C–O), 1182.65 (C–O),

229.71 (C–N), 1326.96 (C–N), 1408.33 (C–C), 1464.05

C–C), 1511.25 (C–C), 1593.93 (C–C), 1666.17.17 (C=O),

(C–Cl), 749.10 (C–Cl), 1123.79 (C–O), 1181.81 (C–O),

1321.18 (C–N), 1406.32 (C–C), 1512.03 (C–C), 1541.01

(C–C), 1610.51 (C=O), 1671.41 (C=O), 3303.41 (C–H),

1

721.61 (C=O), 3062.32 (C–H), 3300.01 (N–H). H NMR

3369.31 (N–H). H NMR (DMSO-d , 400 MHz) δ (ppm):

6

(

DMSO-d , 400 MHz) δ (ppm): 1.32 (3H, t, J = 8.0 Hz,

1.31 (3H, t, J = 8.0 Hz, ester–CH ), 4.31 (2H, q, J = 8.0 Hz,

6

3

ester–CH ), 4.31 (2H, q, J = 8.0 Hz, ester –O–CH ), 7.50

ester–O–CH ), 6.70 (1H, s, Ar–H), 6.72 (1H, s, Ar–H), 7.37

3

2

(

=

8

4

8

4

1H, dd, J = 4.0 Hz, J = 4.0 Hz, Ar–H), 7.84 (1H, dd, J

4.0 Hz, J = 4.0 Hz, Ar–H), 7.96–8.00 (2H, m, Ar–H),

2

(1H, d, J = 4.8 Hz, pyrimidine–H), 7.78 (2H, s, Ar–H &

Ar–H), 7.97 (2H, s, Ar–H & Ar–H), 8.63 (1H, s,

pyrazole–H), 8.70 (1H, d, J = 4.4 Hz, pyrimidine–H), 10.51

1

2

1

.02 (1H, s, pyrazole–H), 8.19 (2H, dd, J = 4.0 Hz, J =

1 2

1

3

.0 Hz, Ar–H), 8.26 (1H, d, J = 4.0 Hz, pyrimidine–H),

(1H,s, amide–NH). C NMR (DMSO-d , 75 MHz) δ

6

.67 (1H, d, J = 4.0 Hz, pyrimidine–H), 8.85 (1H, dd, J =

(ppm): 14.81 (ester CH ), 59.92 (ester CH ), 102.29 (pyr-

1

3

2

3

.0 Hz, J = 4.0 Hz, Ar–H), 10.75 (1H, bs, amide–NH).

C

azole carbon), 109.61 (pyrimid ine carbon), 120.09 (ArC &

ArC), 125.92 (ArC-C=O), 128.83 (ArC & ArC), 131.12

(ArC & ArC), 132.11 (ArC–Cl & ArC–Cl), 135.54 (ArC to

pyrimidine ring & pyrazole carbon), 140.89 (ArC–Cl),

146.65 (ArC–NH), 147.56 (pyrimidine carbon), 148.88

(pyrimidine C-Ar), 153.09 (pyrazolo pyrimidine junction

carbon), 162.18 (amide –C=O), 163.68 (ester –C=O).

LC–MS (ESI, m/z): 490.5 [M+H].

2

NMR (DMSO-d , 75 MHz) δ (ppm): 14.86 (ester CH ),

5

6

3

9.96 (ester CH ), 102.24 (py razole carbon), 109.66

2

(

pyrimidine carbon), 120.18(Ar–C & Ar–C), 125.35

Ar–C), 128.60 (Ar–C), 130.15 (Ar–C), 130.96 (Ar–C &

Ar–C), 131.20 (ArC–C=O), 131.77(ArC ), 135.09

(

ArC–Cl), 135.21 (ArC–Cl), 142.08 (ArC–NH), 146.82

pyrazole carbon), 147.27 (pyrimidine carbon), 148.78

pyrimidine C–Ar), 153.22 (pyrazolo pyri midine junction

carbon), 162.17 (amide –C=O), 163.97 (ester –C=O).

LC–MS (ESI, m/z): 456.1 [M+H].

General procedure for the synthesis of 7-[aryl

(benzoylamino)-phenyl]-pyrazolo [1, 5-a] pyrimidine-3-

carboxylic acid (9 a-h)

7

-[4-(3, 5-Dimethyl-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acid ethyl ester (8g)

To a suspension of the amide ester derivative 8 a–h (2.49

mmol) in methanol: THF (1: 1, 7v), lithium hydroxide

(12.45 mmol) in water (3 v) was added drop wise at room

temperature. The reaction mixture was slowly heated to 50 °

It was obtained as pale yellow solid (0.91 g, 83%). MP:

−

1

2

12.0–212.9 °C. IR (ATR, cm ) υ: 1057.53 (C–O),

Med Chem Res

1

3

C and continued the heating for 4 h. The reaction progress

was monitored by TLC. After completion of the reaction,

the reaction mixture was concentrated under reduced pres-

sure and the residue obtained was acidiﬁed with 3N

hydrochloric acid under ice cold condition. The precipitated

solid was ﬁltered, washed with water and dried under

vacuum. This crude material was further puriﬁed by crys-

tallization from appropriate solvents.

acid–OH). C NMR (DMSO-d , 100 MHz) δ (ppm):

6

103.18 (pyrazole carbon), 111.23 (pyri midine carbon), 118.

08 & 118.32 (d, J = 24.0 Hz, ArC), 118.44 & 118.66 (d,

J_C_F= 22.00 Hz, ArC), 127. 63 & 127.72 (d, J = 9 Hz,

ArC), 128.29 (ArC), 128. 85 & 128.93 (d, J = 8.0 Hz,

2

CF

2

3

CF

3

CF

ArC), 129.79 (ArC), 129.90 (ArC), 131.19 (ArC), 131.44 &

4

131.53 (d, J = 9 Hz, ArC), 134.87 (ArC–Cl ), 134.94

CF

(ArC–Cl ), 136.27 (pyrazole carbon), 145.10 (ArC–NH),

147.45 (pyrimidine carbon), 148.52 (pyrimidine C–Ar),

7

-[5-Fluoro-2-(3-triﬂuoromethyl-benzoylamino)-phenyl]-

152.80 (pyrazolo pyrimidine junction carbon), 158.31 &

160.72 (d, J_C_F= 241.00 Hz), 163.63 (amide –C=O),

1

pyrazolo [1, 5-a] pyrimidine-3-carboxylic acid (9a)

163.94 (acid –C=O). LC–MS (ESI, m/z): 446.3 [M+H].

It was obtained as off white solid (0.62 g, 83%). MP:

33.4–234.2 °C. IR (ATR, cm⁻) υ: 1046.31 (C–F),

1

7-[2-(3, 5-Diﬂuoro-benzoylamino)-5-ﬂuoro-phenyl]-

pyrazolo [1, 5-a] pyrimidine-3-carboxylic acid (9c)

2

1

069.10 (C–F), 1131.00 (C–F), 1162.10 (C–F), 1210.12

(

1

C–O), 1331.10 (C–N), 1416.20 (C–C), 1480.00 (C–C),

521.00 (C–C), 1553.99 (C–C), 1621.30 (C=O), 1669.90

C=O), 3070.32 (C–H), 3249.77 (O–H), 3313.12 (C–N).

It was obtained as off white solid (0.62 g, 83%). MP:

−1

(

246.0–247.1 °C. IR (ATR, cm ) υ: 1100.12 (C–F),

1128.59 (C–F), 1176.07 (C–F), 1248.72 (C–O), 1286.54

(C–O), 1326.52 (C–N), 1407.12 (C–C), 1438.95 (C–C),

1520.38 (C–C), 1542.67 (C–C), 1604.02 (C=O), 1662.53

(C=O), 3087.59 (C–H), 3152.83 (O–H), 3261.63 (N–H).

1

H NMR (DMSO-d , 400 MHz) δ (ppm): 7.33 (1H, d, J =

6

4

.4 Hz, pyrimidine –H), 7.56 (1H, dt, J = 4.2 Hz, J = 8.1

1 2

Hz, Ar–H), 7.58–7.69 (2H, m, Ar–H), 7.70–7.74 (2H, m,

Ar–H), 7.88 (2H, td, J = 4.4 Hz, J = 8.6 Hz, Ar–H), 8.54

1

2

1

(

1H, s, pyrazole–H), 8.78 (1H, d, J = 4.4 Hz,

H NMR (DMSO-d , 400 MHz) δ (ppm): 7. 28 (2H, dd, J

6

1

pyrimidine–H), 10.34 (1H, bs, amide–NH), 12.43 (1H, bs,

= 1.2 Hz, J = 3.2 Hz, Ar–H), 7. 31 (1H, d, J = 4.4 Hz,

2

1

3

acid –OH). C NMR (DMSO-d , 100 MHz) δ (ppm):

pyrimidine–H), 7.46 (1H, 1H, J = 4.0 Hz, J = 8.0 Hz,

6

1

2

1

0

02.14 (pyrazole carbon), 110.28 (pyrimidine carbon), 117.

Ar–H), 7.55 (1H, dt, J = 4.0 Hz, J = 8.0 Hz, Ar–H),

1 2

2

5 & 117.29 (d, J = 24 Hz, ArC), 117.39 & 117.61 (d,

7.68–7.76 (2H, m, Ar–H), 8.56 (1H, s, pyrazole–H), 8.79

(1H, d, J = 4.4 Hz, pyrimidine–H), 10.26 (1H, bs,

CF

2

J_C_F= 22 Hz, ArC), 120.27, 122.98, 125.69 & 128.406 (q,

J_C_F= 271 Hz, Ar-CF ), 124.44, 124.48, 124.52 & 124.56

1

13

amide–NH), 12.4 (1H, bs, acid–OH). C NMR (DMSO-d₆,

3

(

q, J = 4 Hz, ArC), 126. 65 & 126.73 (d, J = 8Hz,

100 MHz,) δ: 103.17 (pyrazole carbon), 107.37, 107.62 &

CF

3

2

ArC), 127. 63 & 127.60 (q, J = 3 Hz, ArC), 127. 93 &

107.88 (t, J = 25.5 Hz, ArC), 111.23 (pyrimidine car-

CF

3

2

1

3

1

27.85 (d, J = 8 Hz, ArC), 128. 61 & 128.29 (q, J

=

bon), 111.27 & 117.34 (d, J = 7 Hz, ArC), 111.46 &

CF

2

2 Hz, ArC), 129.09 (ArC), 131.47 (ArC), 133.03, 133.06,

111. 53(d, J = 7 Hz, ArC), 118.11 & 118.36 (d, J

=

CF

4

2

33.09 & 133.12 (q, J = 3 Hz), 134.49 (pyrazole car-

25 Hz, ArC), 118.47 & 118.69 (d, J = 22 Hz, ArC), 127.

70 & 127.79 (d, J = 9 Hz, ArC), 128.90 & 128.99 (d,

J_C_F= 9 Hz, ArC), 132.72 & 132.75 (d, J = 3Hz, ArC),

137.90, 137.98 & 138.07 (t, J = 8 Hz, ArC), 145.03

CF

4

3

bon), 144.13 & 144.14 (d, J_C_F= 1Hz, ArC), 146.40

CF

3

4

(

pyrimidine carbon), 147.44 (pyrimidine C-Ar), 151.74

CF

3

(

pyrazolo pyrimidine junction carbon), 157.26 & 159.68 (d,

CF

1

J_C_F= 242 Hz, ArC–F), 162.54 (amide –C=O) , 163.74

acid –C=O). LC–MS (ESI, m/z): 445.4 [M+H].

(pyrazole carbon), 147.45 (pyrimidine carbon), 148.53

(

(pyrimidine C–Ar), 152.81 (pyrazolo pyrimidine junction

1

carbon), 158.37 & 160.79 (d, J_C_F= 242 Hz, ArC–F),

1

7

-[2-(3, 4-Dichloro-benzoylamino)-5-Fluoro-phenyl]-

161.21 & 163.67 (d, J = 246 Hz, ArC–F ), 161.34 &

CF

1

pyrazolo [1, 5-a] pyrimidine-3-carboxylic acid (9b)

163.80 (d, J = 246 Hz, ArC–F), 163.64 (amide –C=O),

CF

163.76 (acid –C=O). LC–MS (ESI, m/z): 412.6 [M+H].

It was obtained as pale yellow solid (0.64 g, 85%). MP:

32.5–233.7 °C. IR (ATR, cm⁻) υ: 751.61 (C–Cl), 785.41

1

7-[2-(3, 4-Dichloro-benzoylamino)-phenyl]-pyrazolo [1, 5-

2

(

1

(

3

C–Cl), 1092.91 (C–F), 1161.21 (C–O), 1199.00 (C–O),

295.10 (C–N), 1411.16 (C–C), 1512.69 (C–C), 1541.21

C–C), 1675.63 (C=O), 1700.01 (C=O), 3060.71 (C–H),

a] pyrimidine-3-carboxylic acid (9d)

It was obtained as pale yellow solid (1.02 g, 84%). MP:

1

−1

062.83 (O–H), 3261.32 (N–H). H NMR (DMSO-d , 400

258.1–259.2 °C. IR (ATR, cm ) υ: 626.44 (C–Cl), 750.58

6

MHz) δ (ppm): 7.31 (1H, d, J = 4.4 Hz, pyrimidine–H),

.52–7.60 (2H, m, Ar–H), 7.67–7.76 (4H, m, Ar–H), 8.55

1H, s, pyrazole–H), 8.78 (1H, d, J = 4.0 Hz,

pyrimidine–H), 10.28 (1H, bs, amide–NH), 12.43 (1H, bs,

(C–Cl), 1089.75 (C–O), 1135.64 (C–O), 1232.13 (C–N),

1271.93 (C–N), 1438.55 (C–C), 1485.73 (C–C), 1532.43

7

(

(C–C), 1671.12 (C=O), 1698.25 (C=O), 3083.21 (C–H),

1

3292.45 (O–H), 3333.02 (N–H). H NMR (DMSO-d , 300

6

Med Chem Res

MHz) δ (ppm): 7.28 (1H, d, J = 4.2 Hz, pyrimidine–H),

pyrimidine–H), 8.64 (1H, s, pyrazole–H), 8.82 (1H, d, J =

7

.43–7.48 (1H, m, ArH), 7.57–7.66 (1H, m, ArH),

.69–7.48 (4H, m, ArH), 8.53 (1H, s, pyrazole -H), 8.76

4.4 Hz, pyrimidine -H), 10.72 (1H, bs, amide-NH), 12.41

1

3

(1H, bs, acid-OH). C NMR (DMSO-d , 75 MHz) δ (ppm):

6

(

–

1H, d, J = 4.2 Hz, pyrimidine–H), 10.28 (1H, bs, amide

102.18 (pyrazole carbon), 109.84 (pyrimidine carbon),

120.02 (ArC & ArC), 124.95 (ArC), 128.23 (ArC), 130.31

(ArC), 130.78 (ArC & ArC), 131.02 (ArC–C=O), 131.83

(ArC), 135.27 (ArC–Cl), 135.49 (ArC–Cl), 142.18

(ArC–NH), 146.94 (pyrazole carbon), 147.36 (pyrimidine

carbon), 148.25 (pyrimidine C–Ar), 153.06 (pyrazolo pyr-

imidine junction carbon), 162.19 (amide –C=O), 163.84

(acid –C=O). LC–MS (ESI, m/z): 428.3 [M+H].

1

3

NH), 12.34 (1H, bs, acid -OH). C NMR (DMSO-d , 75

6

MHz) δ: 102.97 (pyrazole carbon), 111.16 (pyrimidine

carbon), 125.83 (ArC), 125.93 (ArC), 126.39 (ArC), 128.21

(

azole carbon), 147.32 (pyrimidine carbon), 148.48 (pyr-

imidine C–Ar), 152.71 (pyrazolo pyrimidine junction

carbon), 163.57 (amide –C=O), 163.74 (acid –C=O).

LC–MS (ESI, m/z): 427.3 [M+H].

ArC), 129.83 (ArC), 131.08 (ArC), 131.53 (ArC), 134.79

ArC–Cl), 135.00 (ArC–Cl), 136.41 (ArC), 146.64 (pyr-

7-[4-(3, 5-Dimethyl-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acid (9g)

7

-[2-(3, 5-Diﬂuoro-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acid (9e)

It was obtained as pale yellow solid (0.60 g, 81%). MP:

−

1

274.9–276.0 °C. IR (ATR, cm ) υ: 1046.88 (C–O),

It was obtained as pale yellow solid (0.90 g, 81%). MP:

1132.09 (C–O), 1184.16 (C–O), 1239.30 (C–N), 1279.28

(C–N), 1412.14 (C–C), 1512.38 (C–C), 1549.39 (C–C),

61.3–262.5 °C. IR (ATR, cm⁻) υ: 1060.26 (C–F),

1

2

1

094.00 (C–F), 1128.12 (C–O), 1172.04 (C–O), 1212.90

1602.78 (C=O), 1674.78 (C=O), 3069.01 (C–H), 3297.91

1

(

1

(

C–N), 1284.64 (C–N), 1435.03 (C–C), 1538.03 (C–C),

594.83 (C–C), 1683.60 (C=O), 1721.90 (C=O), 3083.18

C–H), 3269.05 (N–H), 3259.43 (O–H). H NMR (DMSO-

(N–H). H NMR (DMSO-d , 400 MHz) δ (ppm): 2.36 (6H,

6

s, Ar–CH & Ar–CH ), 7.24 (1H, s, Ar–H), 7.46 (1H, d, J

3

1

= 4.0 Hz, pyrimidine–H), 7.59 (2H,s, Ar–H & Ar–H), 8.02

(2H, d, J = 8.0 Hz, Ar–H), 8.18 (2H, d, J = 8.0 Hz, Ar–H),

8.63 (1H, s, pyrazole–H), 8.81 (1H, d, J = 4.0 Hz,

pyrimidine–H), 10.51(1H, bs, amide–NH), 12.38 (1H, bs,

d₆, 300 MHz) (ppm): 7.26 (1H, d, J = 4.5 Hz,

δ

pyrimidine–H), 7.28–7.30 (2H, m, ArH), 7.42–7.48 (2H, m,

ArH), 7.64–7.78 (3H, m, ArH), 8.53 (1H, s, pyrazole–H),

1

3

8

.77 (1H, d, J = 4.5 Hz, pyrimidine–H), 10.26 (1H, bs,

acid–OH). C NMR (DMSO-d 75 MHz) δ (ppm): 21.25

6,

1

3

amide–NH), 12.36 (1H, bs, acid–OH). C NMR (DMSO-

(Ar–CH & Ar–CH ), 102.18 (pyrazole carbon), 109.65

3 3

d , 75 MHz) δ (ppm): 102.93 (pyrazole carbon), 107.12,

(pyrimidine carbon), 119.49 (ArC & ArC), 124.45 (ArC),

125.12 (ArC & ArC), 130.79 (ArC & ArC), 132.89 (ArC),

135.53 (ArC), 138.14 (ArC–Me & ArC–Me), 141.96

(pyrazole carbon), 146.84 (ArC–NH), 147.08 (pyrimidine

carbon), 148.82 (pyrimidine C–Ar), 153.02 (pyrazolo pyr-

imidine junction carbon), 162.12 (amide –C=O), 165.86

(acid –C=O). LC–MS (ESI, m/z): 387.3 [M+H].

6

2

1

07.46 & 107.80 (t, J = 25.5 Hz, ArC), 111.15 (pyr-

CF

2

imidine carbon), 111.16, 111.32 & 111.49 (t, J_C_F= 12.75

Hz, ArH & ArH), 125.91 (ArC), 126.03 (ArC), 126.48

(

&

ArC), 131.52 (ArC), 136.28 (ArC & ArC), 138.00, 138.12

3

138.24 (t, J = 9Hz, ArC), 146.56 (pyrazole carbon),

CF

1

47.32 (pyrim idine carbon), 148.50 (pyrimidine C–Ar),

52.73 (pyrazolo pyrimidine junction carbon), 160.69 &

1

63.97 (d, J = 246 Hz, ArC-F), 160.86 & 164.14 (d,

7-[4-(2, 4, 6-Trichloro-benzoylamino)-phenyl]-pyrazolo [1,

5-a] pyrimidine-3-carboxylic acid (9h)

CF

1

J_C_F= 246 Hz, ArC–F), 163.47 (amide –C=O), 163.58

acid –C=O). LC–MS (ESI, m/z): 395.3 [M+H].

(

It was obtained as pale yellow solid (0.67 g, 80%). MP:

−1

7

-[4-(3, 4-Dichloro-benzoylamino)-phenyl]-pyrazolo [1, 5-

284.9–286.1 °C. IR (ATR, cm ) υ: 628.79 (C–Cl), 694.65

(C–Cl), 751.18 (C–Cl), 1125.69 (C–O), 1183.83 (C–O),

a] pyrimidine-3-carboxylic acid (9f)

1323.17 (C–N), 1405.21 (C–C), 1514.01 (C–C), 1544.04

It was obtained as pale yellow solid (0.64 g, 80%). MP:

2

(C–C), 1600.67 (C=O), 1668.41 (C=O), 3306.47 (C–H),

83.4–284.5 °C. IR (ATR, cm⁻) υ: 748.12 (C–Cl), 778.64

1

3272.88 (O–H), 3379.31 (N–H). H NMR (DMSO-d , 400

1

6

(

1

(

3

C–Cl), 1139.70 (C–O), 1196.85 (C–O), 1233.74 (C–N),

332.44 (C-N), 1411.25 (C–C), 1473.2 (C–C), 1521.23

C–C), 1678.61 (C=O), 1726.63 (C=O), 3057.78 (C-H),

MHz) δ (ppm): 7.45 (1H, d, J = 4.0 Hz, pyrimidine–H),

7.87 (2H, s, ArH & ArH), 7.87 (2H, d, J = 8.0 Hz, Ar–H),

8.18 (2H, d, J = 8.0 Hz, Ar–H), 8.63 (1H, s, pyrazole-H),

8.82 (1H, d, J = 4.0 Hz, pyrimidine–H), 11.15 (1H, bs,

amide-NH), δ 12.4 (1H, bs, acid-OH). C NMR (DMSO-

d₆, 100 MHz) δ (ppm): 103.08 (pyrazole carbon), 109.65

(pyrimidine carbon), 119.48 (ArC & ArC), 125.94

(ArC–C=O), 128.64 (ArC & ArC), 131.39 (ArC & ArC),

1

252.61 (N–H), 3300.0 (O–H). H NMR (DMSO-d , 400

6

1

3

MHz) δ (ppm): 7.48 (1H, d, J = 4.4Hz, Ar–H), 7.85 (1H, d,

J = 8.4Hz, ArH), 7.97 (1H, dd, J = 2Hz, J = 6.8Hz,

Ar–H), 8.01 (2H, d, J = 8.8 Hz, Ar–H & Ar–H ), 8.20 (2H,

d, J = 8.8 Hz, Ar–H & Ar–H), 8.26 (1H, d, J = 2 Hz,

1

2

Med Chem Res

3

1

32.58 (ArC–Cl & ArC–Cl), 135.52 (ArC to pyrimidine

ring & pyrazole carbon), 141.48 (ArC-Cl), 146.75

ArC–NH), 147.67 (pyrimidine carbon), 148.87 (pyrimidine

C–Ar), 153.05 (pyrazolo pyrimidine junction carbon),

62.26 (amide –C=O), 163.66 (acid –C=O). LC–MS (ESI,

127.62 (ArC), 128.56, 128.60, 128.64 & 128.67 (q, J

=

CF

3

3.51 Hz, ArC), 128.76 & 128.87 (d, J = 8.33 Hz, ArC),

129.12 (ArC), 129.27 (ArC), 128.91, 129.27, 129.63 &

129.99 (q, J_C_F= 46.3 Hz, ArC-CF ), 130.09 (ArC),

132.03 (ArC), 132.54 {ArC –(C=O) –NH}, 132.98 (d,

CF

(

2

3

1

4

m/z): 462.5 [M+H].

J_C_F= 3 Hz, ArC–NH–C=O), 135.46 (pyrazole carbon),

1

36. 97 (ArC–Cl), 145.59 (ArC–CH ), 145.85 (pyrimidine

2

carbon), 146.85 (pyrimidine C–Ar), 152.15 (pyrazolo

pyrimidine junction carbon), 157.82 161.04

General procedure for the synthesis of (10 a–w)

&

1

(

d, J = 242.1Hz, ArC-F), 161.57 (amide –C=O), 164.76

amide –C=O attached to benzyl). LC–MS (ESI, m/z):

CF

The acid (9a–h) (1 mmol) and amine (1 mmol) were dis-

solved in dimethylformamide (5v) under argon atmosphere

and N-ethyl diisopropylamine (3 mmol) was added drop

wise to it at 0 °C and HATU (1.3 mmol) was added lot wise

during a period of 15 min. The reaction medium was slowly

allowed to reach room temperature and stirred for 4 h at

room temperature. The reaction progress was monitored by

TLC. After completion of the reaction, the reaction mixture

was poured to ice cold water and stirred at room tempera-

ture for 30 min and the precipitated solid was ﬁltered,

washed with water and dried under vacuum. This crude

product was further puriﬁed by column chromatography

using 2–5% of methanol in chloroform to get the required

amide.

568.8 [M+H].

7-[5-Fluoro-2-(3-triﬂuoromethyl-benzoylamino)-phenyl]-

pyrazolo [1, 5-a] pyrimidine-3-carboxylic acid 4-methoxy-

benzylamide] (10b)

This compound was prepared by coupling the acid (9a) and

4-methoxy benzyl amine with HATU and puriﬁed by col-

umn chromatography (Chloroform/Methanol, 97:3). It was

obtained as pale yellow solid (157 mg, 83%). MP:

−1

1

57.3–158.4 °C; IR (ATR, cm ) υ: 1034.18 (C–F),

073.71 (C–F), 1120.64 (C–F), 1132.16 (C–F), 1202.64

(C–O), 1244.11 (C–N), 1331.16 (C–N), 1416.56 (C–C),

7

-[5-Fluoro-2-(3-triﬂuoromethyl-benzoylamino)-phenyl]-

1520.59 (C–C), 1549.59 (C–C), 1634.90 (C=O), 1665.87

pyrazolo [1, 5-a] pyrimidine-3-carboxylic acid 2-chloro-

benzylamide] (10a)

(C=O), 3046.55 (C–H), 3329.58 (N–H), 3370.15 (N–H).

1

H NMR (DMSO-d , 300 MHz): δ (ppm): 3.73 (3 H, s,

6

O–CH ), 4.52 (2H, d, J = 5.7 Hz, Ar–CH -), 6.87 (2H, d, J

3

2

This compound was prepared by coupling the acid (9a) and

= 7.2 Hz, Ar-H), 7.28 ( 2H, d, J = 7.5 Hz, Ar-H), 7.35 (1H,

d, J = 3 Hz, Ar–H), 7.55 (1H, t, J = 8.55 Hz, Ar–H), 7.72

(2H, dt, J = 7.8 Hz, J = 15 Hz, Ar–H), 7.79 ( 1H, dt, J =

2

-chloro benzyl amine with HATU and puriﬁed by column

chromatography (Chloroform/Methanol, 98:2). It was

obtained as off-white solid (154 mg, 81%). MP:

1

2

1

12 Hz, J = 5.4 Hz, Ar–H), 7.80–7.88 (3H,m, Ar–H), 8.43

2

−

1

79.1–180.5 °C; IR (ATR, cm ) υ: 763.78 (C–Cl),

051.04 (C–F), 1176.09 (C–F), 1122.65 (C–O), 1240.36

(1H, t, J = 3.6 Hz, amide–NH–benzyl), 8.76 (1H, s, pyr-

azole CH), 8.77 (1H, d, J = 3 Hz, pyrimidine CH), δ 10.39

1

3

(

1

(

3

4

C–O), 1247.31 (C–N), 1327.40 (C–N), 1445.28 (C–C),

489.89 (C–C), 1538.10 (C–C), 1551.98 (C–C), 1649.14

C=O), 1684.77 (C=O), 3076.71 (C–H), 3249.71 (N–H),

(s, 1H, amide –NH–). C NMR (DMSO-d₆_,100 MHz) δ

ppm: 41.89 (benzyl–CH ), 55.51(CH O–Ar), 105.63 (pyr-

2

3

azole carbon), 110.85 (pyrimidine carbon), 114.28 (ArC &

1

2

338.71 (N–H). H NMR (DMSO-d , 300 MHz) δ (ppm):

ArC), 118.07 & 118.31 (d, J = 24 Hz, ArC), 118.60 &

6

CF

2

.66 (2H, d, J = 5.7 Hz, Ar–CH –), 7.31 (2H, t, J = 3.6 Hz,

118.82 (d,

J

= 22 Hz, ArC), 120.21, 122.92, 125.63

2

CF

1

Ar–H), 7.59 (2H, t, J = 5.7 Hz, Ar–H), 7.59 (1H, dt, J = 3

& 128.34 (q, J = 271 Hz, CF ), 124.49, 124.53, 124.57

1

CF 3

3

Hz, J = 8.4 Hz, Ar–H), 7.71 (1H, dt, J = 6.6 Hz, J =

& 124.61 (q, J = 4 Hz, ArC), 127.44 (d, J = 9 Hz,

CF CF

ArC), 128.65, 128.68, 128.71 & 128.74 (q, J = 3 Hz,

ArC), 128.84 & 128.92 (d,

129.38, 129.70 & 130.02 (q, J_C_F= 32 Hz, ArC-CF₃),

2

1

2

3

1

2.9 Hz, Ar–H), 7.81 (2H, dt, J = 3.6 Hz, J = 8.1Hz,

1

2

CF

3

Ar–H), 7.86 (2H, t, J = 8.7 Hz, Ar–H), 7.91 (2H, t, J = 7.5

Hz, Ar–H), 8.55 (1H, t, J = 6 Hz, amide–NH–benzyl), 8.58

J

= 8 Hz, ArC), 129.06,

CF

2

(

1H, s, pyrazole CH), 8.81 (1H, d, J = 4.2Hz, pyrimidine

129.09 (ArC & ArC), 130.16 (ArC), 132.01 (ArC),

132.09 {ArC –(C=O) –NH}, 133.02 (d, J_C_F= 3 Hz,

1

3

4

CH), 10.41 (1H, s, amide –NH–). C NMR (DMSO-d₆,

1

00 MHz) δ (ppm): 40.78 (benzyl–CH ), 105.37 (pyrazole

ArC–NH–C=O), 135.50 (pyrazole carbon), 145.61

2

carbon), 110.89 (pyrimidine carbon), 117.96 & 118.29 (d,

(ArC–CH ), 145.90 (pyrimidine carbon), 146.76 (pyr-

2

J_C_F= 24 Hz, ArC), 118.51 & 118.80 (d, J = 22 Hz,

imidine C–Ar), 152.08 (pyrazolo pyrimidine junction car-

CF

1

ArC), 119.68, 122.39, 126.00 & 128.71 (q, J = 270.9

bon), 158.77(ArC–OCH ), 158.28 & 160.70 (d, J = 242

CF

3

CF

3

Hz, Ar–CF ), 124.40, 124.45, 124.49, 124.53 (q, J

.7 Hz, ArC), 127.31 & 127.43 (d, J_C_F= 8.85 Hz, ArC),

=

Hz, ArC–F), 161.45 (amide –C=O), 164.80 (amide –C=O

attached to benzyl). LC–MS (ESI, m/z): 564.62 [M+H].

3

CF

3

4

Med Chem Res

7

-[5-Fluoro-2-(3-triﬂuoromethyl-benzoylamino)-phenyl]-

J = 8.7 Hz, Ar–H), 7.29 (3H, dt, J = 11.1 Hz, J = 8.7 Hz,

1

2

pyrazolo [1, 5-a] pyrimidine-3-carboxylic acid 4-ﬂuoro-

benzylamide] (10c)

Ar–H), 7.59–7.68 (2H, m, Ar–H), 7.00–7.78 (4H, m,

Ar–H), 8.4 (1H, t, J = 6.1 Hz, amide–NH–benzyl), 8.58

(

1H, s, pyrazole CH), 8.76 (1H, d, J = 4.5 Hz, pyrimidine

1

3

This compound was prepared by coupling the acid (9a) and

CH), 10.31 (1H, s, amide –NH–). C NMR (DMSO-d , 75

6

4

-ﬂuoro benzyl amine with HATU and puriﬁed by column

MHz) δ ppm: 41.84 (benzyl–CH ), 55.44 (CH O–ArC),

2

3

chromatography (Chloroform/Methanol, 98: 2). It was

105.56 (pyrazole carbon), 110.71 (pyrimidine carbon),

2

obtained as off-white solid (158 mg, 85%). MP:

114.23 (ArC & ArC), 117.92 & 118.24 (d, J = 24.45 Hz,

CF

−

1

2

1

61.9–163.2 °C; IR (ATR, cm ) υ: 1076.11 (C–F),

098.20 (C–F), 1125.97 (C–F), 1167.28 (C–F), 1290.63

ArC), 118.47 & 118.77 (d, J = 22.2 Hz, ArC), 127.25 &

127.34 (d, J = 8.85 Hz, ArC), 128.19 (ArC), 128.76 &

128.87 (d, J = 8.33 Hz, ArC), 129.03 (ArC & ArC),

CF

3

CF

3

(

C–O), 1249.1 (C–N), 1332.90 (C–N), 1416.23 (C–C),

CF

1

553.97 (C–C), 1641.66 (C=O), 1676.03 (C=O), 3075.68

129.84 (ArC), 131.10 (ArC), 131.59 (m-ArC-Cl),

1

4

(

C–H), 3253.94 (N–H), 3351.01 (N–H). H NMR (DMSO-

131.93 {ArC –(C=O) –NH, 132.81 & 132.84 (d, J

=

CF

d , 300 MHz) δ (ppm): 4.57 (2H, d, J = 4.5 Hz, Ar–CH –),

2.55 Hz, ArC–NH–C=O), 134.78 (p–ArC–Cl), 134.88

6

2

7

.13 (2H,t, J = 6.6 Hz, Ar–H), 7.42 (3H, dt, J = 3.9 Hz, J

(pyrazole–carbon), 145.45 (ArC–CH ), 145.82 (pyrimidine

1

2

=

(

8

13.8 Hz, Ar–H), 7.65–7.72 (2H, m, Ar–H), 7.78–7.92

4H, m, Ar-H), 8.49 (1H, t, J = 3.8 Hz, amide–NH–benzyl),

.57 (1H, s, pyrazole CH), 8.77 (1H, d, J = 3.2 Hz, pyr-

carbon), 146.70 (pyrimidine C–Ar), 151.99 (pyrazolo pyr-

1

imidine junction carbon), 157.80 & 161.03 (d, J_C_F

=

242.02 Hz), 158.70 (ArC–OCH ), 161.39 (amide –C=O),

3

1

3

imidine CH), 10.39 (1H, s, amide -NH-). C NMR

163.87(amide –C=O attached to benzyl). LC–MS (ESI, m/

z): 565.2 [M+H].

(

DMSO-d 100 MHz) δ ppm: 41.89 (benzyl–CH ), 105.63

6, 2

pyrazole carbon), 110.85 (pyrimidine carbon), 115.23 &

2

1

15.51 (d, J = 21.07 Hz, ArC & ArC), 118.07 & 118.31

7-[2-(3, 4-Dichlorobenzoylamino)-5-ﬂuoro-phenyl]-

pyrazolo [1, 5-a] pyrimidine-3-carboxylic acid 4-ﬂuoro-

benzylamide] (10e)

CF

2

CF CF

2

(

d, J = 24 Hz, ArC), 118.60 & 118.82 (d, J = 22 Hz,

1

ArC), 120.21, 122.92, 125.63 & 128.34 (q, J = 271 Hz,

CF ), 124.49, 124.53, 124.57 & 124.61 (q, J = 4 Hz,

ArC), 127.44 (d, J = 9 Hz, ArC), 128.65, 128.68, 128.71

&

CF

3

CF

3

This compound was prepared by coupling the acid (9b) and

4-ﬂuoro benzyl amine with HATU and puriﬁed by column

chromatography (Chloroform/Methanol, 97: 3). It was

obtained as pale yellow solid (163 mg, 88%). MP:

CF

3

128.74 (q, J = 3 Hz, ArC), 128.84 & 128.92 (d, J

CF

2

=

8 Hz, ArC), 129.06, 129.38, 129.70 & 130.02 (q, J

=

CF

3

1

2 Hz), 129.56 & 129.67 (d, J = 10.70 Hz, ArC & ArC),

30.16 (ArC), 132.01 (ArC), 132.09 {ArC –(C=O) –NH},

33.02 (d, J = 3 Hz, ArC-NH-C=O), 135.50 (pyrazole

CF

−1

174.8–176.1 °C. IR (ATR, cm ) υ: 669.65 (C–Cl), 739.87

(C–Cl), 1026.06 (C–F), 1151.35 (C–F), 1202.94 (C–O),

1239.75 (C–N), 1300.38 (C–N), 1412.28 (C–C), 1495.63

(C–C), 1528.17 (C–C), 1643.96 (C=O), 1677.22 (C=O),

4

CF

carbon), 145.61(ArC-CH ), 145.90 (pyrimidine carbon),

2

1

46.76 (pyrimidine C-Ar), 152.08 (pyrazolo pyrimidine

1

junction carbon), 157.80 & 161.02 (d, J = 241.43 Hz,

ArC–F), 159.89 & 163.10 (d, J = 240.7 Hz, ArC–F),

3070.00 (C–H), 3271.18 (N–H), 3353.63 (N–H). H NMR

CF

1

(DMSO-d , 300 MHz) δ (ppm): 4.58 (2H,d, J = 6.3 Hz,

CF

6

1

61.45 (amide –C=O), 164.80 (amide –C=O attached to

Ar–CH –), 7.13 (2H,t, J = 6.9 Hz, Ar–H), 7.33 (1H, d, J =

2

benzyl). LC–MS (ESI, m/z): 552.41 [M+H].

4.5 Hz, Ar–H), 7.38 (2H, t, J = 5.7 Hz, Ar–H), 7.54–7.62

(2H, m, Ar–H), 7.69–7.79 (4H, m, Ar–H), 8.50 (1H, t, J =

7

-[2-(3, 4-Dichlorobenzoylamino)-5-ﬂuoro-phenyl]-

6 Hz, amide–NH–benzyl), 8.57 (1H, s, pyrazole CH), 8.78

pyrazolo [1, 5-a] pyrimidine-3-carboxylic acid 4-methoxy-

benzylamide] (10d)

(1H, d, J = 4.5 Hz, pyrimidine CH), 10.31 (1H, s, amide

–NH–). C NMR (DMSO-d , 75 MHz) δ ppm: 41.68

6

1

3

(

benzyl–CH ), 105.49 (pyrazole carbon), 110.74 (pyr-

2

This compound was prepared by coupling the acid (9b) and

imidine carbon), 115.33 & 115.61 (d, J = 21.07 Hz, ArC

& ArC), 117.91 & 118.24 (d, J_C_F= 24.75 Hz, ArC),

118.48 & 118.77 (d, J_C_F= 22.12 Hz, ArC), 127.25 &

127.37 (d, J = 8.85 Hz, ArC), 128.19 (ArC), 128.77 &

128.88 (d, J_C_F= 8.32 Hz, ArC), 129.58 & 129.69

(d, J = 10.70 Hz, ArC & ArC), 129.83 (ArC), 131.10

(ArC), 131.59 (m–ArC–Cl), 132.81 & 132.84 (d, J

CF

2

4

-methoxy benzyl amine with HATU and puriﬁed by col-

2

umn chromatography (Chloroform/Methanol, 96: 4). It was

obtained as off-white solid (157 mg, 83%). MP:

3

CF

3

−

1

(

1

(

3

(

84.1–185.3 °C. IR (ATR, cm ) υ: 610.45 (C–Cl), 755.67

C–Cl), 1146.55 (C–F), 1175.36 (C–O), 1241.17 (C–N),

293.46 (C–N), 1486.03 (C–C), 1519.03 (C–C), 1554.18

C–C), 1592.99 (C–C), 1627.55 (C=O), 1667.24 (C=O),

034.65 (C–H), 3089.65 (C–H), 3308.80 (N–H), 3345.91

3

CF

4

=

CF

2.4 Hz, ArC–NH–C=O), 134.78 (p–ArC–Cl), 134.89

{ArC –(C=O) –NH}, 136.34 (pyrazole –carbon), 145.45

1

N–H). H NMR (DMSO-d , 300 MHz) δ (ppm): 3.73 (3H,

(ArC–CH ), 145.85 (pyrimidine carbon), 146.75 (pyr-

6

2

s, O–CH ), 4.52 (2H, d, J = 5.7 Hz, Ar–CH –), 6.89 (2H,d,

imidine C–Ar), 152.02 (pyrazolo pyrimidine junction

3

2

Med Chem Res

1

carbon), 157.81 & 161.03 (d, J = 241.43 Hz), 159.99 &

1

1489.89 (C–C), 1538.10 (C–C), 1551.98 (C–C), 1649.14

CF

1

63.20 (d, J_C_F= 240.75 Hz), 161.53 (amide –C=O),

63.88 (amide –C=O attached to benzyl). LC–MS (ESI, m/

(C=O), 1684.77 (C=O), 3076.71 (C–H), 3249.71 (N–H),

1

3338.71 (N–H). H NMR (DMSO-d , 300 MHz) δ (ppm):

6

z): 553.6 [M+H].

4.66 (2H, d, J = 8 Hz, Ar–CH –), 7.31 (3H, dt, J = 4.2 Hz,

2

1

J₂= 8.2 Hz, Ar–H), 7.34 (2H, d, J = 4 Hz, Ar–H),

7.38–7.40 (1H, m, Ar–H), 7.45–7.49 (2H, m, Ar–H), 7.57

(1H,t, J = 3 Hz, Ar–H), 7.70–7.70 (2H, m, Ar–H), 8.55

(1H, t, J = 3 Hz, amide–NH–benzyl), 8.59 (1H, s, pyrazole

CH), 8.80 (1H, d, J = 8.9 Hz, pyrimidine CH), 10.32 (1H, s,

7

-[2-(3, 4-Dichlorobenzoylamino)-5-ﬂuoro-phenyl]-

pyrazolo [1, 5-a] pyrimidine-3-carboxylic acid 2-chloro-

benzylamide] (10f)

1

3

This compound was prepared by coupling the acid (9b) and

amide –NH–). C NMR (DMSO-d , 75 MHz) δ ppm :

6

2

-chlorobenzyl amine with HATU and puriﬁed by column

40.80 (benzyl–CH ), 105.36 (pyrazole carbon), 107.22,

2

chromatography (Chloroform/Methanol, 97: 3). It was

obtained as off-white solid (160 mg, 84%). MP:

107.56 & 107.90 (t, J = 25.5 Hz, ArC), 110.79 (pyr-

CF

2

imidine carbon), 111.18 & 111.42 (d, J = 24 Hz), 111.29

& 111.53 ( d, J = 24 Hz), 117.96 & 118.29 (d, J

24.75 Hz), 118.53 & 118.83(d, J = 22.50 Hz), 127.35 &

127.47(d, J = 9 Hz), 127.65 (ArC), 128.86 & 128.97 (d,

CF

−1

2

1

(

1

(

85.2–186.6 °C. IR (ATR, cm ) υ: 695.73 (C–Cl), 743.05

C–Cl), 785.95 (C–Cl), 1193.52 (C–F), 1027.80 (C–O),

156.24 (C–O), 1193.52 (C–N), 1294.17 (C–N), 1410.59

C–C), 1477.34 (C–C), 1517.38 (C–C), 1547.08 (C–C),

627.51 (C=O), 1663.61 (C=O), 3032.04 (C–H), 3257.81

=

CF

2

CF

3

CF

3

J_C_F= 8.25 Hz, ), 129.12 (ArC), 129.29 (ArC), 129.64

1

(ArC), 132.56 (ArC–NH–C=O), 132.72 (pyrazole carbon),

136.97 (ArC-Cl), 137.82, 137.93 & 138.04 {ArC –(C=O)

1

(

N–H), 3356.14 (N–H). H NMR (DMSO-d , 300 MHz) δ

6

(

ppm): 4.67 (2H, d, J = 6 Hz, Ar–CH -), 7.33 (3 H, dt, J =

–NH}, 145.44 (ArC–CH ), 145.85 (pyrimidine carbon),

2

1

2

5

.6 Hz, J = 9 Hz, Ar–H), 7.40–7.39 (1H, m, Ar–H), 7.45

146.88 (pyrimidine C–Ar), 152.17 (pyrazolo pyrimidine

2

1

(

1H, dd, J = 6 Hz, J = 9 Hz, Ar–H), 7.57–7.63 (2H, m,

junction carbon), 157.88 & 161.11(d, J_C_F= 242.25 Hz,

1

2

1

Ar–H), 7.71–7.79 (4H, m, Ar–H), 8.57 (1H, t, J = 9 Hz,

amide–NH–benzyl), 8.59 (1H, s, pyrazole CH), 8.81 (1H, d,

J = 9 Hz, pyrimidine CH), 10.32 (1H, s, amide –NH–).

ArC–F), 160.74 & 164.02 (d, J = 233.25 Hz, ArC–F),

CF

1

160.91 & 164.19 (d, J = 246 Hz, ArC–F), 161.60 (amide

CF

1

3

C

–C=O), 163.66 (amide –C=O attached to benzyl). LC–MS

(ESI, m/z): 536.4 [M+H].

NMR (DMSO-d , 75 MHz) δ ppm: 41.69 (benzyl–CH ),

6

2

1

05.42 (pyrazole carbon), 110.72 (pyrimidine carbon),

2

17.90 & 118.23 (d, J_C_F= 24.75 Hz, ArC), 118.49 &

2

18.78 (d, J = 22.12 Hz, ArC), 127.23 & 127.35 (d,

7-[2-(3, 5-Diﬂuorobenzoylamino)-5-ﬂuoro-phenyl]-

pyrazolo [1, 5-a] pyrimidine-3-carboxylic acid 4-methoxy-

benzylamide] (10h)

CF

3

J_C_F= 8.85 Hz, ArC), 128.17 (ArC), 128.61 & 128.78 (d,

J_C_F= 8.32 Hz, ArC), 129.33 (ArC), 129.44 (ArC), 129.69

3

(

ArC), 130.07 (ArC), 131.17 (ArC), 131.57 (m–ArC–Cl),

4

1

32.09 (ArC), 132.81 & 132.84 (d, J_C_F= 2.4 Hz,

ArC–NH–C=O), 132.91{ArC –(C=O) –NH}, 134.71

p–ArC–Cl), 136.89 (pyrazole–carbon), 136.67 (ArC–Cl),

45.39 (ArC–CH ), 145.83 (pyrimidine carbon), 146.71

This compound was prepared by coupling the acid (9c) and

4-methoxy benzyl amine with HATU and puriﬁed by

column chromatography (Chloroform/Methanol, 96: 4).

It was obtained as off white solid (162 mg, 84%). MP:

(

1

2

−1

(

pyrimidine C–Ar), 151.99 (pyrazolo pyrimidine junction

235.1–235.9 °C. IR (ATR, cm ) υ: 1025.74 (C–F),

1064.06 (C–F), 1131.84 (C–F), 1165.72 (C–O), 1180.06

(C–O), 1198.08 (C–O), 1247.96 (C–N), 1320.9 (C–N),

1423.37 (C–C), 1442.25 (C–C), 1493.59 (C–C), 1515.29

1

carbon), 157.80 & 161.02 (d, J = 241.43 Hz), 159.96 &

1

CF

1

63.17 (d, J_C_F= 240.75 Hz), 161.55 (amide –C=O),

63.86 (amide –C=O attached to benzyl). LC–MS (ESI, m/

z): 569.5 [M+H].

(C–C), 1528.89 (C–C), 1645.60 (C=O), 1675.16 (C=O),

1

3077.87 (C–H), 3252.63 (N–H), 3343.81 (N–H). H NMR

7

-[2-(3, 5-Diﬂuorobenzoylamino)-5-ﬂuoro-phenyl]-

(DMSO-d , 300 MHz) δ (ppm): 3.72 (3H, s, Ar–OCH ),

6 3

pyrazolo [1, 5-a] pyrimidine-3-carboxylic acid 2-chloro-

4.52 (2H, d, J = 6.0 Hz, Ar–CH –), 6.88 (2H,d, J = 8.4 Hz,

2

benzylamide] (10g)

Ar–H), 7.26–7.32 (5H, m, Ar–H), 7.46 (1H, t, J = 9.2 Hz,

Ar–H), 7.54 (1H, t, J = 5.6 Hz, Ar–H), 7.76–7.69 (2H, m,

Ar–H), 8.37 (1H, t, J = 6 Hz, amide–NH–benzyl), 8.58 (1H,

s, pyrazole CH), 8.76 (1H, d, J = 4.2 Hz,–pyrimidine CH),

This compound was prepared by coupling the acid (9c)

and 2-chloro benzyl amine with HATU and puriﬁed by

column chromatography (Chloroform/Methanol, 98: 2). It

1

3

10.29 (1H, s, amide –NH–). C NMR (DMSO-d 75 MHz)

6

,

was obtained as pale yellow solid (159 mg, 82%). MP:

δ ppm :41.87 (benzyl–CH ), 55.48 (CH O–Ar), 105.57

2 3

95.4–196.7 °C. IR (ATR, cm⁻) υ: 763.78 (C–Cl),

1

(pyrazole carbon), 107.48 (t, J = 25.68 Hz, ArC), 110.71

2

1

CF

2

051.04 (C–F), 1176.09 (C–F), 1122.65 (C–O), 1240.36

(pyrimidine carbon), 111.19 & 111.42 (d, J = 17.47 Hz),

CF

2

(

C–O), 1247.31 (C–N), 1327.40 (C–N), 1445.28 (C–C),

111.30 & 111.54 (d, J_C_F= 17.47 Hz), 114.27 (ArC &

Med Chem Res

2

ArC), 117.99 & 118.31 (d, J = 24.68 Hz), 118.54 &

7-[2-(3, 4-Dichloro-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acid 2-chloro-benzylamide]

(10j)

CF

3

CF CF

2

1

18.83 (d, J = 22.28 Hz), 127.41 (d, J = 8.92 Hz),

28.95 (d, J = 8.92 Hz), 129.04 (ArC & ArC), 131.95

ArC-NH-C=O), 132.72 (pyrazole carbon), 137.89 (t, J_C_F

8.43 Hz, {ArC–(C=O) –NH}, 145.42 (ArC-CH ), 145.84

pyrimidine carbon), 146.74 (pyrimidine C-Ar), 152.04

pyrazolo pyrimidine junction carbon), 157.89 & 161.124

d, J = 241.87 Hz, ArC–F), 158.73 (ArC-OCH ), 160.75

164.03 (d, J = 246.00 Hz, ArC–F), 160.92 & 164.19

3

CF

3

(

=

This compound was prepared by coupling the acid (9d) and

2-chloro benzyl amine with HATU and puriﬁed by column

chromatography (chloroform/methanol, 98: 2). It was

obtained as off white solid (162 mg, 84%). MP:

2

(

1

CF

3

1

−1

&

(

194.2–195.4 °C. IR (ATR, cm ) υ: 694.89 (C–Cl), 746.62

CF

1

d, J_C_F= 245.77 Hz, ArC–F), 161.43 (amide –C=O),

63.65 (amide –C=O attached to benzyl). LC–MS (ESI, m/

z): 532.4 [M+H].

(C–Cl), 781.79 (C–Cl), 1032.55 (C–O), 1122.55 (C–O),

1173.82 (C–O), 1247.17 (C–N), 1305.99 (C–N), 1439.29

(C–C), 1478.11 (C–C), 1536.68 (C–C), 1598.24 (C–C),

1

654.51 (C=O), 1671.83 (C=O), 3049.78 (C–H), 3255.64

1

(N–H), 3348.02 (N–H). H NMR (DMSO-d , 300 MHz) δ

6

7

-[2-(3, 5-Diﬂuorobenzoylamino)-5-ﬂuoro-phenyl]-

(ppm): 4.62 (2H, d, J = 5.65 Hz, Ar–CH –), 7.28–7.58 (6H,

2

pyrazolo [1, 5-a] pyrimidine-3-carboxylic acid 4-ﬂuoro-

benzylamide] (10i)

m, Ar–H), 7.62–7.76 (6H, m, Ar–H), 8.52 (2H, m,

amide–NH–benzyl & pyrazole CH ), 8.75 (1H, d, J = 3.2

1

3

Hz, pyrimidine CH), 10.28 (1H,s, amide –NH–). C NMR

(DMSO-d , 75 MHz) δ ppm: 41.90 (benzyl–CH ), 105.46

This compound was prepared by coupling the acid (9c) and

6

2

4

-ﬂuoro benzyl amine with HATU and puriﬁed by column

(pyrazole carb on), 110.73 (pyrimidine carbon), 125.58

(ArC), 126.03 (ArC), 126.47 (ArC), 127.98 (ArC), 129.33

(ArC), 129.69 (ArC), 130.07 (ArC), 131.15 (ArC attached

to pyrimidine), 131.17 (ArC), 131.52 (ArC), 131.48 (ArC),

131.73 {ArC –(C=O) –NH}, 131.57 (m–ArC–Cl), 131.96

chromatography (chloroform/methanol, 97: 3). It was

obtained as off white solid (153 mg, 81%). MP:

−1

2

1

52.4–253.9 °C. IR (ATR, cm ) υ: 1061.20 (C–F),

120.97 (C–F), 1165.02 (C–F), 1213.42 (C–F), 1155.21

(

1

(

3

C–O), 1240.51 (C–N), 1291.92 (C–N), 1425.27 (C–C),

499.73 (C–C), 1539.49 (C–C), 1596.04 (C–C), 1641.27

C=O), 1672.32 (C=O), 3063.19 (C–H), 3251.73 (N–H),

(pyrazole

carbon),

134.71

(p–ArC–Cl),

134.88

(ArC–NH–C=O), 136.48 (p–ArC–Cl), 145.77 (ArC–CH₂),

146.72 (pyrimidine carbon), 147.10 (pyrimidine C–Ar),

152.07 (pyrazolo pyrimidine junction carbon), 161.46

(amide –C=O), 163.73 (amide –C=O attached to benzyl).

LC–MS (ESI, m/z): 551.6 [M+H].

1

329.23 (N–H). H NMR (DMSO-d , 300 MHz) δ (ppm):

6

4

.57 (2 H, d, J = 6.0 Hz, Ar–CH –), 7.15 (2H, t, J = 8.8 Hz,

2

Ar–H), 7.29–7.38 (5H, m, Ar–H), 7.47 (1H, t, J = 9.2 Hz,

Ar–H), 7.58 (1H, t, J = 5.6 Hz, Ar–H), 7.76–7.69 (2H, m,

Ar–H), 8.49 (1H, t, J = 6.4 Hz, amide–NH–benzyl), 8.58

7-[2-(3, 4-Dichloro-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acid 4-ﬂuoro-benzylamide]

(10k)

(

1H, s, pyrazole CH), 8.78 (1H, d, J = 4.4 Hz, pyrimidine

1

3

CH), 10.29 (1H, s, amide –NH–). C NMR (75 MHz,

DMSO-d ) δ ppm: 41.73 (benzyl–CH ), 105.52 (pyrazole

6

2

carbon), 107.27, 107.61 & 107.95 (t, J_C_F= 25.58 Hz,

This compound was prepared by coupling the acid 9d and

4-ﬂuoro benzyl amine with HATU and puriﬁed by column

chromatography (chloroform/methanol, 98: 2). It was

obtained as pale yellow solid (161 mg, 86%). MP:

188.2–189.1 °C. IR (ATR, cm ) υ: 699.52 (C–Cl), 758.38

(C–Cl), 1032.69 (C–F), 1099.54 (C–O), 1156.09 (C–O),

1228.94 (C–N), 1300.36 (C–N), 1443.36 (C–C), 1555.31

ArC), 110.77 (pyrimidine carbon), 111.22 & 111.46 (d,

2

3

J_C_F= 23.5 Hz, ArC), 111.33 & 11.57 (d, J = 23.5 Hz,

CF

2

ArC), 115.39 & 115.68 (d, J = 21.15 Hz, ArC), 118.01

CF

2

−1

&

118.34 (d, J = 24.75 Hz, ArC), 118.57 & 118.86 (d,

CF

2

3

J_C_F= 21.98 Hz, ArC), 127.39 & 127.51 (d, J = 8.93

CF

3

Hz, ArC), 128.89 & 129.00 (d, J_C_F= 8.48 Hz, ArC),

29.60 & 129.71 (d, J_C_F= 8.03 Hz, ArC), 132.75

3

1

(C–C), 1638.07 (C=O), 1677.39 (C=O), 3079.87 (C–H),

1

(

1

ArC–NH–C=O), 136.43 (pyrazole carbon), 137.96,

38.02 & 138.07 (t, J_C_F= 8.4 Hz, {ArC –(C=O) –NH}),

3261.84 (N–H), 3365.20 (N–H). H NMR (DMSO-d , 300

6

3

MHz) δ (ppm): 4.58 (2H, d, J = 5.6 Hz, Ar–CH –), 7.15

2

1

45.44 (ArC–CH ), 145.89 (pyrimidine carbon), 146.82

(2H, t, J = 8.6 Hz, Ar–H), 7.31 (1H, d, J = 4.4 Hz, Ar–H),

7.39 (2H, t, J = 6.8 Hz, Ar–H), 7.47 (1H, t, J = 7.4 Hz,

Ar–H), 7.60 (1H, t, J = 4 Hz, Ar–H), 7.66–7.79 (5H, m,

Ar–H), 8.5 (1H, t, J = 5.8 Hz, amide–NH–benzyl), 8.56

2

(

pyrimidine C–Ar), 152.10 (pyrazolo pyrimidine junction

1

carbon), 157.92 & 161.15 (d, J = 242.18 Hz, ArC-F),

CF

1

61.59 (amide –C=O), 160.04 & 163.26 (d, J = 240.9

CF

1

Hz, ArC–F), 160.77 & 164.06 (d, J_C_F= 246.38 Hz,

ArC–F), 160.94 & 164.22 (d, J = 246.08 Hz, ArC–F),

(1H, s, pyrazole CH), 8.77 (1H, d, J = 4.4 Hz, pyrimidine

1

13

CH), 10.32 (1H, s, amide –NH–). C NMR (DMSO-d , 75

CF

6

1

63.68 (amide –C=O attached to benzyl). LC–MS (ESI, m/

MHz) δ ppm: 41.90 (benzyl–CH ), 105.46 (pyrazole car-

2

z): 520.3 [M+H].

bon), 110.73 (pyrimi dine carbon), 115.35 & 115.63 4.26

Med Chem Res

2

(

d, J_C_F= 21.07 Hz, ArC

&

ArC), 125.58 (ArC),

column chromatography (Chloroform/Methanol, 96: 4). It

was obtained as pale yellow solid (162 mg, 83%). MP:

212.6–213.8 °C; IR (ATR, cm ) υ: 1023.82 (C–F),

1

26.03 (ArC), 126.47 (ArC), 127.98 (ArC), 129.59 &

3

−1

1

29.70 (d, J = 10.70 Hz, ArC & ArC), 131.15 (ArC

CF

attached to pyrimidine), 131.52 (ArC), 131.48 (ArC),

1130.05 (C–F), 1149.12 (C–O), 1174.85 (C–O), 1189.12

(C–O), 1206.12 (C–O), 1248.16 (C–N), 1320.91 (C–N),

1499.05 (C–C), 1515.02 (C–C), 15.34.51 (C–C), 1551.75

1

31.73 {ArC –(C=O) –NH}, 131.96 (pyrazole carbon),

34.88 (ArC–NH–C=O), 135.04 (m–ArC–Cl), 136.48

1

(

p–ArC–Cl), 145.77 (ArC–CH ), 146.72 (pyrimidine car-

(C–C), 1647.32 (C=O), 1678.00 (C=O), 3081.90 (C-H),

2

1

bon), 147.10 (pyrimidine C–Ar), 152.07 (pyrazolo pyr-

imidine junction carbon), 160.00 & 163.30 (d, J

3279.01 (N–H), 3370.34 (N–H). H NMR (DMSO-d , 400

6

1

=

MHz) δ (ppm): 3.72 (3H,s, Ar–OMe), 4.52 (2H, d, J = 6

CF

2

–

47.50 Hz, ArC-F), 161.46 (amide –C=O), 163.73 (amide

C=O attached to benzyl). LC–MS (ESI, m/z): 535.4

Hz, Ar–CH ), 6.89 (2H, d, J = 8.8 Hz, Ar–H), 7.27 (2H, d,

2

J = 8.4Hz, Ar–H), 7.28–7.31 (3H, m, Ar–H), 7.44–7.49

(2H, m, Ar–H), 7. 66–7.69 (1H, dt, J = 1.6 Hz, J = 7.6

[

M+H].

1

2

Hz, Ar–H), 7.73 (1H, d, J = 8.0 Hz, Ar–H), 7.78–7.80 (1H,

dd, J = 1.6 Hz, J = 7.6 Hz, Ar–H), 8.39 (1H, t, J = 6 Hz,

amide–NH–benzyl), 8.56 (1H, s, pyrazole CH), 8.75 (1H, d,

7

-[2-(3, 4-Dichloro-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acid 4-metho xy-benzylamide]

10l)

1

2

(

J = 4.8 Hz, pyrimidine CH), 10.30 (1H, bs, Amide-NH).

1

3

C

NMR (DMSO-d₆, 75MHz)

δ

ppm: 41.85

This compound was prepared by coupling the acid 9d and

-methoxy benzyl amine with HATU and puriﬁed by col-

umn chromatography (chloroform/methanol, 97: 3). It was

obtained as off white solid (168 mg, 88%). MP:

(benzyl–CH ), 55.45 (CH O–ArC), 105.39 (pyrazole car-

2

3

2

4

bon), 107.14, 107.48 & 107.82 (t, J = 25.7 Hz, ArC),

CF

2

110.64 (pyrimidine carbon), 111.17 &, 111.409 (d, J

=

CF

2

17.55 Hz, ArC), 111.28 &, 111.52 (d, J_C_F= 17.55 Hz,

ArC), 114.25 (ArC & ArC), 125.64 (ArC), 126.01 (ArC),

126.48 (ArC), 129.03 (ArC & ArC), 131.50 (ArC), 131.67

−

1

2

(

1

(

1

(

07.1–208.4 °C. IR (ATR, cm ) υ: 740.03 (C–Cl), 770.20

C–Cl), 1033.46 (C–O), 1066.38 (C–O), 1135.45 (C–O),

173.91 (C–O), 1234.99 (C–N), 1302.40 (C–N), 1434.38

C–C), 1462.20 (C–C), 1486.99 (C–C), 14620.20 (C–C),

605.03 (C=O), 1657.79 (C=O), 3046.67 (C–H), 3241.01

(ArC-attached to pyrimidine), 131.94 (ArC–NH–C=O),

3

136.29 (pyrazole carbon), 137.99, 138.10 & 138.21 (t, J

CF

= 8.48 Hz, {ArC –(C=O) –NH}), 145.75 (ArC-CH₂),

146.77 (pyrimidine carbon), 147.02 (pyrimidine C–Ar),

1

N–H), 3349.53 (N–H). H NMR (DMSO-d , 400 MHz) δ

6

ppm): 3.73 (3H, s, Ar–OCH ), 4.52 (2H, d, J = 6 Hz,

151.99 (pyrazolo pyrimidine junction carbon), 158.72

3

1

Ar–CH ), 6.89 (2H, d, J = 8.4 Hz, ArH), 7.29 (3H,t, J= 7.7

(ArC–OCH ), 160.71 & 163.99 (d, J_C_F= 246.08 Hz,

2

3

1

Hz, ArH), 7.46 (1H,t, J = 3.8 Hz, ArH), 7.59 (1H, d, J =

ArC–F), 160.88 & 164.16 (d, J = 245.93 Hz, ArC–F),

CF

6

.4 Hz, ArH), 7.65–7.79 (5H, m, ArH), 8.39 (1H, t, J = 6,

163.47 (amide –C=O), 163.49 (amide –C=O attached to

benzyl). LC–MS (ESI, m/z): 514.4 [M+H].

Hz, amide–NH–benzyl), 8.55 (1H, s, pyrazole CH ), 8.75

(

–

1H, d, J = 4 Hz, pyrimidine CH), 10.33 (1H, s, amide

1

3

NH–). C NMR (DMSO-d , 75 MHz) δ ppm: 41.86

7-[2-(3, 5-Diﬂuoro-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acid 2-chloro -benzylamide]

(10n)

6

(

benzyl–CH ), 55.49 (CH O–ArC), 105.42 (pyrazole car-

2 3

bon), 110.70 (pyrimidine carbon), 114.26 (ArC & ArC),

1

25.57 (ArC), 125.93 (ArC), 126.41 (ArC), 128.24 (ArC),

29.08 (ArC & ArC), 129.89 (ArC & ArC), 131.11 (ArC

This compound was prepared by coupling the acid (9e) and

2-chloro benzyl amine with HATU and puriﬁed by column

chromatography (chloroform/methanol, 96: 4). It was

obtained as pale yellow solid (157 mg, 80%). MP:

217.4–218.8 °C. IR (ATR, cm ) υ: 763.78 (C–Cl),

1051.04 (C–F), 1176.09 (C–F), 1122.65 (C–O), 1240.36

(C–O), 1247.31 (C–N), 1327.40 (C–N), 1445.28 (C–C),

1489.89 (C–C), 1538.10 (C–C), 1551.98 (C–C), 1649.14

attached to pyrimidine), 131.51 (ArC), 131.58 (ArC),

1

31.68 {ArC –(C=O) –NH}, 131.98 (pyrazole carbon),

34.83 (ArC–NH–C=O), 135.00 (m–ArC–Cl), 136.45

−1

(

p–ArC–Cl), 145.78 (ArC–CH ), 146.77 (pyrimidine car-

2

bon), 147.11 (pyrimidine C–Ar), 152.01 (pyrazolo pyr-

imidine junction carbon), 158.73 (ArC–OCH ), 161.48

3

(

amide –C=O), 163.77 (amide –C=O attached to benzyl).

LC–MS (ESI, m/z): 547.2 [M+H].

(C=O), 1684.77 (C=O), 3076.71 (C–H), 3249.71 (N–H),

1

3

338.71 (N–H). H NMR (DMSO-d , 400 MHz) δ (ppm):

6

7

-[2-(3, 5-Diﬂuoro-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acid 4-metho xy-benzylamide]

10m)

4.66 (2H, d, J = 6.4 Hz, Ar-CH ), 7.29–7.33 (5H, m,

Ar–H), 7.38–7.41 (1H, m, Ar–H), 7.43–7.50 (3H, m,

2

(

Ar–H), 7. 66–7.70 (1H, dt, J = 1.6 Hz, J = 7.2 Hz, Ar–H),

1

2

7

.74 (1H, d, J = 7.2 Hz, Ar–H), 7.78–7.81(1H, dd, J = 1.2

1

This compound was prepared by coupling the acid (9e) and

-methoxy benzyl amine with HATU and puriﬁed by

Hz, J₂= 6.8 Hz, Ar–H), 8.56 (2H, t, J = 4.4 Hz,

amide–NH–benzyl & pyrazole CH ), 8.79 (1H,d, J = 4.4

4

Med Chem Res

1

3

Hz, pyrimidine CH), 10.31 (1H, bs, Amide–NH). C NMR

(

(amide –C=O attached to benzyl). LC–MS (ESI, m/z):

553.2 [M+H].

DMSO-d , 100 MHz) δ ppm: 40.63 (benzyl–CH ), 105.23

6 2

2

pyrazole carbon), 107.32, 107.58 & 107.84 (t, J_C_F= 26

Hz, ArC), 110.81 (pyrimidine carbon), 111.31 & 111.50 (d,

J_C_F= 19 Hz, ArC), 111.38 & 111.57 (d, J_C_F= 19 Hz,

ArC), 125.67 (ArC), 126.09 (ArC), 126.55 (ArC), 127.73

7-[2-(3, 4-Dichloro-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acid morpho lino

propionamide] (10p)

2

(

ArC), 129.19 (ArC), 129.34 (ArC), 129.70 (ArC), 131.57

ArC), 131.77 (ArC-attached to pyrimidine), 132.61

This compound was prepared by coupling the acid (9d) and

morpholinopropyl amine with HATU and puriﬁed by col-

umn chromatography (chloroform/methanol, 96:4). It was

obtained as pale yellow solid (169 mg, 87%). MP:

227.2–228.3 °C. IR (ATR, cm ) υ: 740.03 (C-Cl), 770.20

(C–Cl), 1033.46 (C–O), 1066.38 (C–O), 1135.45 (C–O),

1173.91 (C–O), 1234.99 (C–N), 1302.40 (C–N), 1434.38

(C–C), 1462.20 (C–C), 1486.99 (C–C), 14620.20 (C–C),

ArC–NH–C=O), 136.35 (pyrazole carbon), 137.05

3

ArC–Cl), 138.09, 138.17 & 138.25 (t, J = 8 Hz, {ArC –

CF

C=O) –NH}), 145.85 (ArC–CH ), 146.99 (pyrimidine

2

−

1

carbon), 147.12 (pyrimidine C–Ar), 152.23 (pyrazolo pyr-

imidine junction carbon), 161.21 & 163.67 (d, J = 246

Hz, ArC–F), 161.34 & 163.80 (d, J = 246 Hz, ArC–F),

1

CF

1

CF

61.73 (amide –C=O), 163.58 (amide –C=O attached to

benzyl). LC–MS (ESI, m/z): 518.8 [M+H].

1605.03 (C=O), 1657.79 (C=O), 3046.67 (C–H), 3241.01

1

(

N–H), 3349.53 (N–H). H NMR (DMSO-d , 400 MHz) δ

6

(

ppm): 1.69 (2H, t, J = 8 Hz, –CH –), 2.34 (6 H, t, J = 8

2

7

-[2-(3, 5-Diﬂuoro-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acid 3,4-dichloro -benzylamide]

10o)

Hz, –N–CH –), 3.39 (2H,t, J = 4 Hz, –NH–CH –), 3.55

2

(4H,t, J = 4 Hz, O–CH –), 7.29 (1H, d, J = 8 Hz, Ar–H),

2

(

7.46 (1H, t, J = 8 Hz, Ar–H), 7.58 (1H,d, J = 4 Hz, Ar–H),

7.78–7.66 (5H, m, Ar–H), 8.11 (1H, t, J = 4 Hz,

This compound was prepared by coupling the acid (9e) and

,4-dichloro benzyl amine with HATU and puriﬁed by

amide–NH–benzyl), 8.50 (1H, s, pyrazole CH), 8.75 (1H, d,

1

3

J = 4 Hz, pyrimidine CH),10.32 (1H, s, Amide–NH).

C

column chromatography (Chloroform/Methanol, 95: 5). It

NMR (DMSO-d 75 MHz) δ ppm: 26.63 (−CH –), 37.24

6

,

2

was obtained as pale yellow solid (159 mg, 76%). MP:

2

(−CH –NH–C=O), 53.84 (−CH – attached to N from

2 2

32.1–233.3 °C. IR (ATR, cm⁻) υ: 763.77 (C–Cl), 778.57

1

morpholine &–CH – attached to N from morpholine), 56.46

2

(

1

(

1

(

C–Cl), 1053.04 (C–F), 1177.05 (C–F), 1120.55 (C–O),

250.37 (C-O), 1248.32 (C–N), 1324.43 (C–N), 1447.29

C–C), 1499.89 (C–C), 1548.10 (C–C), 1551.88 (C–C),

648.14 (C=O), 1683.78 (C=O), 3076.72 (C–H), 3248.71

(−CH -attached to morpholine), 66.60 (–CH – attached to

2

O from morpholine & –CH – attached to O from morpho-

2

line), 105.68 (pyrazole carbon), 110.64 (pyrimidine car-

bon), 125.70 (ArC) , 125.97 (ArC), 126.44 (ArC), 28.25

(ArC), 129.88 (ArC), 131.12 (ArC), 131.56 {ArC –(C=O)

–NH}, 131.61 (ArC), 131.69 (ArC-NH-C=O), 134.84

(pyrazole carbon), 135.01 (m–ArC–Cl) 136.48 (p–ArC–Cl),

1

N–H), 3348.71 (N–H). H NMR (DMSO-d , 400 MHz) δ

6

ppm): 4.58 (2H,d, J = 6.4 Hz, Ar–CH ), 7.28–7.35 (4H, m,

2

Ar–H), 7.44–7.50 (2H, m, Ar–H), 7.58–7.60 (2H, m,

Ar–H), 7. 66–7.70 (1H, dt, J = 1.6 Hz, J = 7.2 Hz, Ar–H),

145.72 (ArC–CH ), 146.64 (pyrimidine carbon), 147.10

1

2

7

1

.74 (1H, d, J = 7.2 Hz, Ar–H), 7.78–7.80 (1H, dd, J =

(pyrimidine C-Ar), 151.90 (pyrazolo pyrimidine junction

carbon), 161.48 (amide –C=O), 163.73 (amide –C=O

attached to benzyl). LC–MS (ESI, m/z): 554.3 [M+H].

1

.2 Hz, J = 7.6 Hz, Ar–H), 8.56 (1H, s, pyrazole CH), 8.60

2

(

1H, t, J = 6.0 Hz, amide–NH–benzyl ), 8.78 (1H,d, J = 4.4

1

3

Hz, pyrimidine CH), 10.30 (1H, bs, Amide–NH). C NMR

(

2

DMSO-d 75 MHz) δ ppm : 41.47 (benzyl–CH ), 105.19

7-[2-(3, 4-Dichloro-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxy lic acid 2-chlorophenethylamide]

(10q)

6

,

2

pyrazole carbon), 107.14, 107 .48 & 107.82 (t, J_C_F

=

5.57 Hz, ArC), 110.76 (pyrimidine carbon), 111.18 &

2

1

11.41 (d, J = 17.62 Hz, ArC), 111.29 & 111.52 (d,

CF

2

J_C_F= 17.70 Hz, ArC), 125.64 (ArC), 126.03 (ArC),

26.49 (ArC), 127.99 (ArC), 129.64 (ArC), 130.90

This compound was prepared by coupling the acid (9d) and

2-chloro phenethyl amine with HATU and puriﬁed by

column chromatography (chloroform/methanol, 97: 3). It

was obtained as off-white solid (154 mg, 78%). MP:

1

(

m–ArC–Cl), 131.31 (ArC), 131.49 (ArC-attached to pyr-

imidine), 131.68 (ArC–NH–C=O), 136.31 (pyrazole car-

bon), 137.99, 138.11 & 138.21 (t, J = 8.33 Hz, {ArC –

3

−1

198.2–199.1 °C. IR (ATR, cm ) υ: 694.89 (C–Cl), 746.62

CF

(

1

C=O) –NH}), 141.66 (p-ArC-Cl), 145.82 (ArC-CH₂),

46.89 (pyrimidine carbon), 147.03 (pyrimidine C–Ar),

(C–Cl), 781.79 (C–Cl), 1032.55 (C–O), 1122.55 (C–O),

1173.82 (C–O), 1247.17 (C–N), 1305.99 (C–N), 1439.29

(C–C), 1478.11 (C–C), 1536.68 (C–C), 1598.24 (C–C),

52.06 (pyrazolo pyrimi dine junction carbon), 160.72 &

1

63.99 (d, J = 245.85 Hz, ArC–F), 160.88 & 164.16 (d,

1654.51 (C=O), 1671.83 (C=O), 3049.78 (C–H), 3255.64

CF

1

J_C_F= 246.08 Hz, ArC–F), 161.79 (amide –C=O), 163.50

(N–H), 3348.02 (N–H). H NMR (DMSO-d , 400 MHz) δ

6

Med Chem Res

(

1

ppm): 3.00 (2H, t, J = 7.2 Hz, Ar–CH ), 3.62 (2H, dt, J =

(amide –C=O), 166.62 (amide –C=O attached to benzyl).

LC–MS (ESI, m/z): 506.4 [M+H].

2

1

.3 Hz, J₂= 6.8 Hz, –CH –NH), 7.24–7.28 (3H,m,

2

Ar–H), 7.37–7.47 (3H, m, Ar–H), 7.57–7.59 (1H, m,

Ar–H), 7.66–7.77 (5H, m, Ar–H), 8.11 (1H, t, J = 4 Hz ,

amide–NH–benzyl), 8.49 (1H, s, pyrazole CH), 8.71

7-[4-(3, 5- Dimethyl-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acid 4-ﬂuorobenzylamide] (10s)

(

1H, d, J = 4.0 Hz, pyrimidine-CH), 10.32 (1H, bs,

1

3

Amide–NH). C NMR (DMSO-d₆_,75 M Hz ) δ (ppm):

This compound was prepared by coupling the acid (9g) and

4-ﬂuoro benzyl amine with HATU and puriﬁed by column

chromatography (chloroform/methanol, 97: 3). It was

obtained as pale yellow solid (153 mg, 80%). MP:

268.4–269.8 °C. IR (ATR, cm ) υ: 1040.82 (C–O),

1116.42 (C–O), 1176.07 (C–F), 1179.26 (C–O), 1238.39

(C–N), 1333.09 (C–N), 1413.19 (C–C), 1465.73 (C–C),

1515.32 (C–C), 1552.12 (C–C), 1599.36 (C–C), 1601.12

3

3.64 (benzyl–CH ), 38.78 (-CH -NH), 105.52 (pyrazole

2

carbon), 110.72 (pyrimidine carbon), 125.67 (ArC), 126.00

(

ArC), 126.49 (ArC), 127.71 (ArC), 128.29 (ArC), 128.71

ArC), 129.74 (ArC), 129.94 (ArC), 131.16 (ArC-attached

−

1

to pyrimidine), 131.57 (ArC), 131.64 (ArC), 131.66 (ArC),

31.73 {ArC –(C=O) –NH}, 133.70 (ArC–Cl), 134.90

m–ArC–Cl), 135.02 (ArC–NH–C=O), 136.51 (pyrazole

carbon), 137.17 (p–ArC–Cl), 145.71 (ArC–CH ), 146.74

1

(

(C=O), 1653.26 (C=O), 3068.19 (C–H), 3309.89 (N–H),

2

1

(

pyrimidine carbon), 147.14 (pyrimidine C-Ar), 151.89

pyrazolo pyrimidine junction carbon), 161.62 (amide

3384.70 (N–H). H NMR (DMSO-d ,300 MHz) δ (ppm):

6

2.39 (6H, s, Ar–Me), 4.61 (2H, d, J = 5.7 Hz, -NH-CH -),

2

–

C=O), 163.76 (amide –C=O attached to benzyl). LC–MS

7.17 (2H, dt, J = 2.1 Hz, J = 9 Hz, Ar–H), 7.27 (1H, s,

1

2

(

ESI, m/z): 565.2 [M+H].

Ar–H), 7.43 (2H, t, J = 6.0 Hz, Ar–H), 7.52 (1H, d, J = 4.5

Hz, Ar–H), 7.61 (2H, s, Ar–H), 8.05 (2H, d, J = 8.7 Hz,

Ar–H), 8.25 (2H,d, J = 8.7 Hz, Ar–H), 8.58 (1H, t, J = 5.7

Hz, amide-NH–benzyl), 8.69 (1H, s, pyrazole CH),

8.83 (1H, d, J = 4.8 Hz, pyrimidine–CH), 10.55 (s, 1H,

7

-[4-(3, 5- Dimethyl-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acid 4-methoxybenzylamide]

10r)

1

3

(

Amide–NH). C NMR (DMSO-d , 100 MHz) δ ppm:

6

2

1.32 (CH –Ar & CH –Ar), 40.88 (benzyl–CH ), 105.32

3 3 2

This compound was prepared by coupling the acid (9g) and

-methoxy benzyl amine with HATU and puriﬁed by col-

(pyrazole carbon), 109.85 (pyrimidine carbon), 115.49 &

2

4

115.70 (d, J = 21 Hz, ArC & ArC), 120.00 (ArC &

CF

umn chromatography (Chloroform/Methanol, 96:4). It was

obtained as off-white solid (162 mg, 83%). MP:

ArC), 124.72 (ArC), 125.92 (ArC & ArC), 129.74 & 129.

3

82 (d, J = 8 Hz, ArC & ArC), 130.98 (ArC & ArC),

CF

−

1

2

1

57.2–258.7 °C. IR (ATR, cm ) υ: 1041.94 (C–O),

115.33 (C–O), 1179.22 (C–O), 1239.29 (C–N), 1333.07

131.95 (ArC-NH-C=O & ArC attached to pyrimidine), &

ArC), 133.58 {ArC–(C=O) –NH}, 135.04 (pyrazole car-

bon), 138.12 (ArC–CH & ArC–CH ), 142.78 (ArC–CH ),

(

1

C–N), 1413.09 (C–C), 1465.76 (C–C), 1515.32 (C–C),

552.12 (C–C), 1599.36 (C–C), 1601.12 (C=O), 1653.26

C=O), 3068.19 (C–H), 3309.89 (N–H), 3384.70 (N–H).

3

2

146.09 (pyrimidine carbon), 147.11 (pyrimidine C–Ar),

(

152.09 (pyrazolo pyrimidine junction carbon), 158.25 &

1

H NMR (DMSO-d , 300 MHz) δ (ppm): 2.39 (6H, s,

160.66 (d, J_C_F= 241.70 Hz, ArC-F), 161.57 (amide

6

Ar–Me), 3.74 (3H,s, O–Me), 4.56 (2H, d, J = 6.0 Hz,

NH–CH –), 6.91 (2H, d, J = 8.7 Hz, Ar–H), 7.27 (1H, s,

–C=O), 166.72 (amide –C=O attached to benzyl). LC–MS

(ESI, m/z): 494.4 [M+H].

–

2

Ar–H), 7.31 (2H,d, J = 8.7 Hz, Ar–H), 7.51 (1H,d, J = 4.5

Hz, Ar–H), 7.61 (2H, s, Ar–H), 8.06 (2H, d, J = 8.7 Hz,

Ar–H), 8.25 (2H, d, J = 8.7 Hz, Ar–H), 8.47 (1H,t, J = 4

Hz, amide-NH–benzyl), 8.68 (1H, s, pyrazole CH), 8.82

7-[4-(2,4,6-Trichloro-benzoylamino)-phenyl]-pyrazolo [1,

5-a] pyrimidine-3-carboxylic acid 4-methoxybenzylamide]

(10t)

(

1H,d, J = 4.5 Hz, pyrimidine–CH), 10.55 (1H, s,

1

3

Amide–NH). C NMR (DMSO-d , 75 MHz) δ ppm: 21.28

This compound was prepared by coupling the acid (9h) and

4-methoxy benzyl amine with HATU and puriﬁed by col-

umn chromatography (Chloroform/Methanol, 96:4). It was

obtained as pale yellow solid (149 mg, 79%). MP:

274.2–275.5 °C. IR (ATR, cm ) υ: 664.12 (C-Cl), 693.90

(C-Cl), 736.92 (C-Cl), 1023.80 (C-O), 1060.54 (C-O),

1116.21 (C-O), 1181.79 (C-O), 1237.15 (C-N), 1323.79 (C-

N), 1412.07 (C-C), 1588.88 (C-C), 1509.36 (C-C), 1548.51

6

(

CH –Ar

&

CH –Ar), 40.80 (benzyl–CH₂), 55.49

3

Ar–OCH ), 105.37 (pyra zole carbon), 108.85 (pyrimidine

3

carbon), 114.28 (ArC & ArC), 120.00 (ArC & ArC ),

1

−

1

24.72 (ArC), 125.90 (ArC & ArC), 129.13 (ArC & ArC),

30.98 (ArC & ArC), 131.95 (ArC–NH–C=O & ArC

attached to pyrimidine & ArC), 133.58 {ArC –(C=O)

NH}, 135.04 (pyrazole carbon), 138.08 (ArC–CH₃

ArC–CH ), 142.81 (ArC–CH ), 146.01 (pyrimidine car-

–

&

(C-C), 1610.73 (C=O), 1696.46 (C=O), 3063.73 (C-H),

3

2

1

bon), 147.18 (pyrimidine C-Ar), 152.15 (pyrazolo pyr-

3255.36 (N-H), 3378.71 (N-H). H NMR (DMSO-d , 400

6

imidine junction carbon), 158.74 (ArC–OCH ), 161.51

MHz) δ (ppm): 3.73 (3H, s, Ar-OMe), 4.55 (2H, d, J = 4.0

3

Med Chem Res

Hz, -NH-CH -), 6.90 (2H,d, J = 8.0 Hz, Ar-H), 7.30 (2H, d,

J = 8.0 Hz, Ar-H), 7.47 (1H,d, J = 4.0 Hz, Ar–H), 7.88

7-[4-(3, 4- Dichloro-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acid 4-metho xybenzylamide]

(10 v)

2

(

1H, s, Ar–H), 7.91 (2H, d, J = 8.7 Hz, Ar–H), 8.24 (2H, d,

J = 8.0 Hz, Ar–H), 8.45 (1H, t, J = 8.0 Hz,

amide–NH–benzyl), 8.66 (1H,s, pyrazole CH), 8.81 (1H, d,

J = 4.0 Hz, pyrimidine–CH), 11.17 (s, 1H, Amide–NH).

This compound was prepared by coupling the acid (9f) and

4-methoxy benzyl amine with HATU and puriﬁed by col-

umn chromatography (Chloroform/Methanol, 96: 4). It was

obtained as off white solid (147 mg, 77%). MP:

1

3

C

NMR (DMSO-d₆, 75 MHz)

δ

ppm: 41.90

(

benzyl–CH ), 55.47 (Ar–OCH ), 105.45 (pyrazole C),

2

3

−1

1

&

09.01 (pyrimidine C), 114.26 (ArC & ArC), 119.47 (ArC

ArC), 125.64 {ArC –(C=O) –NH}, 128.57 (ArC &

ArC), 129.12 (ArC & ArC), 131.35 (ArC & ArC), 131.91

pyrazole C), 132.54 (ArC–NH–C=O & ArC attached to

pyrimidine), 135.46 (m–ArC–Cl & m–ArC–Cl), 141.61

ArC–CH ), 146.01 (pyrimidine C), 146.99 (p–ArC–Cl),

306.9–307.8 °C. IR (ATR, cm ) υ: 744.85 (C–Cl), 770.80

(C–Cl), 1033.16 (C–O), 1113.27 (C–O), 1142.91 (C–O),

1174.97 (C–O), 1243.15 (C–N), 1334.59 (C–N), 1414.81

(C–C), 1465.80 (C–C), 1515.21 (C–C), 1548.71 (C–C),

1599.50 (C–C), 1645.22 (C=O), 1678.38 (C=O), 3063.47

(

1

(

(C–H), 3251.10 (N–H), 333.62 (N–H). H NMR (DMSO-

2

1

47.08 (pyrimidine C–Ar), 152.16 (pyrazolo pyrimidine

d₆, 400 MHz) δ (ppm): 3.73 (3H, s, Ar–OMe), 4.54 (2H, d,

junction carbon), 158.74 (ArC–OCH ), 161.48 (amide

J = 4.0 Hz, –NH–CH –), 6.91 (2H, d, J = 8.0 Hz, Ar–H),

3

2

–

C=O), 162.21 (amide –C=O attached to benzyl). LC–MS

7.31 (2H, d, J = 8.0 Hz, Ar–H), 7.50 (1H, d, J = 4.0 Hz,

Ar–H), 7.86 (2H, d, J = 8.0 Hz, Ar–H), 7.97–8.04 (3H, m,

Ar–H), 8.26 (3H, d, J = 8.0 Hz, Ar–H), 8.46 (1H, t, J = 8.0

Hz, amide–NH–benzyl), 8.67 (1H, s, pyrazole CH), 8.81

(1H, d, J = 4.0 Hz, pyrimidine–CH), 10.75 (1H, s,

(

ESI, m/z): 581.7 [M+H].

7

5

-[4-(2,4,6-Trichloro-benzoylamino)-phenyl]-pyrazolo [1,

-a] pyrimidine-3-carboxylic acid 4-ﬂuorobenzylamide]

1

3

(

10u)

Amide–NH). C NMR (DMSO–d , 75 MHz) δ ppm: 41.89

6

(

benzyl–CH ), 55.49 (ArC–OCH ), 105.51 (pyrazole C),

2 3

This compound was prepared by coupling the acid (9h) and

-ﬂuoro benzyl amine with HATU and puriﬁed by column

chromatography (Chloroform/Methanol, 97: 3). It was

109.09 (pyrimidine C), 114.43 (ArC & ArC), 119.43 (Ar

C), 125.66 {ArC –(C=O) –NH}, 128.63 (ArC & ArC),

129.34 (ArC & ArC), 131.45 (ArC & ArC), 131.98 (Ar C),

132.12 (ArC attached to pyrimidine), 132.61

(ArC–NH–C=O), 134.10 (m–ArC–Cl), 136.13 (pyrazole

4

obtained as pale yellow solid (155 mg, 84%). MP:

1

2

58.6–259.8 °C. IR (ATR, cm⁻) υ: 612.14 (C–Cl), 639.72

(

1

(

1

C–Cl), 670.82 (C–Cl), 1070.53 (C–F), 1118.28 (C–O),

158.75 (C–O), 1240.2 (C–O), 1190.33 (C–O), 1233.66

C–N), 1326.20 (C–N), 1415.97 (C–C), 1434.91 (C–C),

510.47 (C–C), 1522.99 (C–C), 1545.37 (C–C), 1638.38

C=O), 1691.40 (C=O), 3093.94 (C–H), 3227.80 (N–H),

carbon), 141.68 (ArC–CH ), 146.09 (p–ArC–Cl), 147.03

2

(pyrimidine C), 147.34 (pyrimidine C–Ar), 152.26 (pyr-

azolo pyrimidine junction carbon), 158.83 (ArC–OCH₃),

161.51 (amide –C=O), 162.67 (amide –C=O attached to

benzyl). LC–MS (ESI, m/z): 547.4 [M+H].

(

1

3

4

2

7

322.80 (N–H). H NMR (DMSO-d , 400 MHz) δ (ppm):

6

.60 (2H, d, J = 4.0 Hz, –NH–CH –), 7.16 (2H, dt, J =

7-[4-(3, 4- Dichloro-benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acid 4-ﬂuoro benzylamide] (10

w)

2

1

.0 Hz, J = 8.0 Hz, Ar-H), 7.42 (2H, t, J = 4.0 Hz, Ar–H),

2

.48 (1H, d, J = 4.0 Hz, Ar–H), 7.88 (1H, s, Ar–H), 7.92

(

8

2H, d, J = 8.7 Hz, Ar–H), 8.24 (2H, d, J = 8.0 Hz, Ar–H),

.56 (1H, t, J = 8.0 Hz, amide–NH–benzyl), 8.66 (1H, s,

pyrazole CH), 8.83(1H, d, J = 8.0 Hz, pyrimidine–CH),

This compound was prepared by coupling the acid (9f) and

4-ﬂuoro benzyl amine with HATU and puriﬁed by column

chromatography (chloroform/methanol, 97:3). It was

obtained as pale yellow solid (142 mg, 76%). MP:

1

3

1

1.18 (1H, s, Amide–NH). C NMR (DMSO-d , 100

6

MHz) δ ppm: 41.87 (benzyl–CH ), 105.76 (pyrazole C),

2

−1

1

09.27 (pyrimidine C), 114.33 (ArC & ArC), 114.51 &

313.5–314.6 °C. IR (ATR, cm ) υ: 747.14 (C–Cl), 768.35

(C–Cl), 1032.98 (C–F), 1099.91 (C–O), 1130.31 (C–O),

1178.28 (C–O), 1198.24 (C–O), 1238.29 (C–N), 1278.01

(C–N), 1416.16 (C–C), 1469.64 (C–C), 1514.46 (C–C),

1523.10 (C–C), 1552.39 (C–C), 1647.20 (C=O), 1683.66

2

14.71 (d, J = 22 Hz, ArC & ArC), 126.99 {ArC –

CF

(

C=O) –NH}, 128.47 (ArC & ArC), 129.85 & 129.93 (d,

3

J_C_F= 8 Hz, ArC & ArC), 131.75 (ArC & ArC), 132.08

pyrazole C), 132.50 (ArC-NH-C=O & ArC attached to

pyrimidine), 136.39 (m–ArC–Cl & m–ArC–Cl), 141.68

ArC–CH ), 146.07 (pyrimidine C), 146.89 (p–ArC–Cl),

(

1

(C=O), 3061.78 (C–H), 3228.9 (N–H), 3324.04 (N–H). H

(

NMR (DMSO-d , 400 MHz) δ (ppm): 4.60 (2H, d, J = 4.0

2

6

1

47.18 (pyrimidine C–Ar), 152.15 (pyrazolo pyrimidine

Hz, –NH–CH –), 7.17 (2H, dt, J = 2.3 Hz, J = 8.0 Hz,

2

1

2

1

junction carbon), 158.57 & 160.98 (d, J_C_F= 241.43 Hz,

ArC–F), 161.40 (amide –C=O), 162.29 (amide –C=O

attached to benzyl). LC–MS (ESI, m/z): 569.8 [M+H].

Ar–H), 7.42 (2H, t, J = 4.0 Hz, Ar–H), 7.51 (1H,d, J = 4.0

Hz, Ar–H), 7.86 (1H, d, J = 8.0 Hz, Ar–H), 7.97–8.04 (3H,

m, Ar–H), 8.26 (2H, d, J = 8.0 Hz, Ar–H), 8.57 (1H, t, J =

Med Chem Res

4

.0 Hz, amide–NH–benzyl), 8.67 (1H, s, pyrazole CH), 8.82

medium was replaced with MTT solution (100 µL, 5 mg/mL

in MEM medium) for further 4 h. The supernatant was

carefully aspirated and the precipitated crystals of Formazan

blue were solubilized by adding DMSO (200 µL) and

optical density was measured at wavelength of 570 nm

using LISA microplate reader. The results were represented

out in triplicates for each concentration. Concentration at

which the optical density (O.D) of treated cells was reduced

by 50% with respect to the untreated control. Calculation of

the percentage of lyses of cells was done by comparing the

O.D of sample to that of the control and also by microscopic

analysis.

(

1H, d, J = 4.0 Hz, pyrimidine CH), 10.75 (1H, s,

1

3

Amide–NH). C NMR (DMSO-d , 75 MHz) δ ppm: 41.87

6

(

benzyl–CH ), 105.88 (pyrazole C), 109.65 (pyrimidine C),

2

1

14.51 & 114.71 (d, J = 22 Hz, ArC & ArC), 119.13

CF

(

ArC), 125.86 {ArC –(C=O) –NH}, 128.33 (ArC & ArC),

3

1

29.85 & 129.93 (d, J = 8 Hz, ArC & ArC), 131.42

CF

(

ArC & ArC), 131.78 (ArC), 132.42 (ArC attached to

pyrimidine), 132.81 (ArC–NH-C=O), 134.44 (m–ArC–Cl),

36.73 (pyrazole carbon), 141.98 (ArC–CH ), 146.19

1

2

(p–ArC–Cl), 147.23 (pyrimidine C), 147.74 (pyrimidine

C–Ar), 152.06 (pyrazolo pyrimidine junction carbon),

1

58.57 & 160.98 (d, J_C_F= 241.43 Hz, ArC-F), 161.41

(

amide –C=O), 162.77 (amide –C=O attached to benzyl).

LC–MS (ESI, m/z): 535.4 [M+H].

Results and discussion

Chemistry

Anticancer activity

All compounds were screened for their in vitro anticancer

activity against representative human cancer cell line (HeLa

cell line) by MTT assay (Chiruvella et al. 2008; Edmondson

et al. 1988; Prasad et al. 2005). This is a colorimetric assay

that measures the reduction of yellow 3-(4, 5-dimethythia-

zol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) by

mitochondrial succinate dehydrogenase. The MTT enters

the cells and passes into the mitochondria where it is

reduced to an insoluble, colored (dark purple) formazan

product. The cells are then solubilized with an organic

solvent (eg, Dimethylsulfoxide, Isopropanol) and then

released solubilized formazan reagent is measured spectro-

photometrically. Since reduction of MTT can only occur in

metabolically active cells, the level of activity is a measure

of the viability of these cells.

The 3-(4, 5-dimethythiazol-2-yl)-2, 5-diphenyl tetra-

zolium bromide (MTT) was made a solution in such a way

that 10 mg was dissolved in 10 mL of Hank’s balanced

solution. The cell lines were maintained in 96 wells micro

titer plate containing MEM media supplemented with 10%

heat inactivated fetal calf serum, containing 5% of mixture

of Gentamycin, Penicillin (100 Units/mL) and Streptomycin

Substituted pyrazolo [1, 5-a] pyrimidine amide derivatives

described herein were synthesized by the convergent

approach of three consecutive schemes. First part involves

the synthesis of 7-(substituted amino-phenyl)-pyrazolo [1,

5-a] pyrimidine-3-carboxylic acid methyl ester fragment

(7a-c) by the following procedures as shown in Scheme 1.

The syntheses of ﬁrst two steps were carried out as per the

reported procedure (Gopalaswamy et al. 2009). (i) Synthesis

of enamine derivatives were achieved by condensing the

corresponding acetophenones (1a–c) with dimethylforma-

0

mide dimethylacetal at 110 C for 6–8 h. The products were

isolated by removing the excess amount of reagents under

reduced pressure followed by crystallization using appro-

priate solvents. (ii) Pyrazolo [1, 5-a] pyrimidine cyclization

was achieved by treating the enamine derivative with ethyl

5-amino-1-H-pyrazole-4-carboxylate (4) in acetic acid

medium under mild heating (Zhang et al. 2014). These

compounds were puriﬁed by ﬂash column chromatography

over silica gel using 2–5% of methanol in chloroform as

eluent to get brown colour material followed by an ethyl

acetate slurry process to get pale yellow solid. Then, our

initial attempts to convert the bromo functional group to

amine were not successful by conventional methods. Our

detailed literature survey revealed that this conversion can

also be achieved by coupling benzophenone imine with

bromo derivative under Buchwald –Hartwig condition

(Louie and Hartwig 1995). The above literature protocol

was adopted with slight modiﬁcation by through screening

on base, ligand and palladium analogues to get moderate

yield. The optimum yield was observed with dibenzylidine

acetone palladium as the catalyst and xanthphos as the

ligand with cesium carbonate as base in 1, 4-dioxane sol-

vent under reﬂux condition. The imines 6a–c were isolated

by ﬂash column chromatography using 40–60% of ethyl

acetate in hexanes as eluent followed by crystallization

(

100 µg / mL) in presence of 5% CO at 37 °C for 3–4 days.

2

Then after, remove the supernatant and replace MEM media

with Hank’s balanced solution and the cells were incubated

overnight. The in-vitro growth inhibitions of test com-

pounds were assessed by calorimetric or spectrophotometric

method. This helps to determine the conversion of MTT

into formazan blue by living cells. Remove the supernatant

from the plate, add fresh Hank’s balanced salt solution and

treated with different concent ration of compound (approx

diluted with DMSO). The marketed anticancer drug cis-

platin was tested as a reference compound in the assay. The

control group contains only DMSO. After 24 h of incuba-

tion at 37 °C in a humidiﬁed atmosphere of 5% CO , the

2

Med Chem Res

F

Br

O

1

a

0

DMF-DMA, 110 C, 5h

Step -1

F

O

F

O

Step-2

O

Step-4

N

Br

Step - 3

AcOH,

O

N

+

N

NH₂

N

Pd dba ,Xanthphos

Br

O

2

3

DMF-DMA, AcOH,

DMF

H

N

0

N

7

2 C,4h

0

O

Cs CO , 1,4-Dioxane, 110 C, 5h

2

3

O

3

O

NH -NH .H O,

4

2

a

₀0_C_,₂_h

6a

5

a

O

Cl

F

R1

O

F

O

N

Step- 8

R1

H N

H

2

Step- 6

Step- 7

N

Step- 5

N

R1

N

H

R1

N

H

N

H N

2

H

LiOH

DMAc

N

R2

6

N HCl, EtOH, RT, 1 h

O

R2

O

N

O

OH

O

HATU

10a-i

9

a-c

7

a

8a-c

R1

-Trifluoromethyl

,4-Dichloro

,5-Difluoro

R2

3

2- Chloro

4-Methoxy

4-Fluoro

3

Scheme 1 Synthetic route to synthesize of derivatives 10 a–i

either with ethanol or methanol. Finally, the amines 7a–c

were synthesized by hydrolyzing the imines under acidic

condition as per the reported procedure (Xin et al. 2011).

The second sequence in the synthesis of substituted

pyrazolo [1, 5-a] pyrimidine amide derivatives involved the

synthesis of 7-[aryl (benzoylamino)-phenyl]-pyrazolo [1, 5-

a] pyrimidine-3-carboxylic acids 9 a–h in two steps as

shown in Scheme 2. The amines obtained by the above

synthetic approach were further derivatised to the corre-

sponding amides 8 a–h by reacting with substituted acid

chlorides. All the amides were puriﬁed by ﬂash column

chromatography and then crystallized using appropriate

solvents. Our initial attempts for the hydrolysis of the above

esters with sodium hydroxide heating gave rise to the

cleaved amide product. Finally, the saponiﬁcations of these

amide esters were achieved by using lithium hydroxide as a

base under mild heating to yield the corresponding acid

derivatives 9 a–h.

the required product because of solubility problem of the

acid. Finally, the above acid derivatives were coupled with

substituted amines to form a series of amide derivatives 10

a–w in good yields using HATU as coupling agent as

shown in Scheme 3.

The structures of all the newly synthesized compounds

1

13

were conﬁrmed by IR, H NMR and C NMR and LC MS

spectral studies. The IR spectrum of 2c revealed the pre-

sence of carbonyl group due to the appearance of strong

−

1

band at 1634.29 cm , while that of =C-H bend from

−

1

enamine were observed at 752.72 cm and 889.29 cm-

respectively. In addition to that, the –C=C– stretch values

1

were observed at 1533.69 and 1574.08 cm- , while that of

-

1

–C–N– stretch were observed at 1231.55 and 1268.39 cm ,

1

respectively. In its H NMR spectrum, the N-substituted

methyl groups were observed as two singlets at δ 2.92 and δ

3.10 ppm. The structure of ethyl 5-amino-1H-pyrazole-4-

carboxylate 4 was conﬁrmed by a series of spectral studies.

−

1

The third sequence in the synthesis of the target com-

pounds involved the synthesis of 10 a-w, as shown in

Scheme 3. Our initial trials were based on making the

corresponding acid chloride and coupling with substituted

amines. However, this attempt resulted in low conversion to

FTIR spectrum showed a broad band at 3193.79 cm

indicating the stretching of the –NH in the pyrazole ring.

−1

Also, the peaks were observed at 1615.86 cm for N–H

−

1

bend and 1337.61 cm for C–N stretch respectively. H

NMR spectrum showed a singlet with a chemical shift of

Med Chem Res

Br

O

1

b

DMF-DMA,110 C, 5h

Step -1

O

Step- 2

O

Step - 3

Step-4

Br

N

O

N

+

N

NH

N

H

N

DMF-DMA, AcOH, DMF

NH -NH .H O, 50 C,2h

Br

O

N

Pd dba ,Xanthphos

2

b

AcOH, 72 C,4h

O

N

4

O

Cs CO , 1,4-Dioxane, 110 C, 5h

O

3

O

5

b

6b

O

N

H N

Step- 8

R1

R2

H

Step- 5

Step- 7

N

Step- 6

N

H

R1

H

R1

N

H

N

O

H N

N

LiOH

O

6

N HCl, EtOH, RT,

O

N

R2

O

Cl

R1

DMAc

OH

O

HATU

10j-q

7

b

8d-e

9

d-e

R1

,4-Dichloro

,5-Difluoro

R2

3

2- Chloro

3

4-Methoxy

-Fluoro

,4 -Dichloro

4

3

Scheme 2 Synthetic route to synthesize of derivatives 10 j–q

7

.45 ppm for the proton in the pyrazole ring. In addition to

presence of the pyrazolo pyrimidine junction carbon in the

molecule. The structure of 5a was further conﬁrmed by LC

MS. It showed the molecular ion peak at m/z 367.0 (M

+2H), which conforms to its molecular formula. The for-

mations of the corresponding imine compounds 6 a–c were

that, the broad singlet at δ 11.84 ppm conﬁrmed the pre-

sence of the –NH proton in the pyrazole ring. We have

observed signals at 94.00, 139.93 and 151.86 ppm in

NMR spectrum, which were consistent with the aromatic

carbons of the pyrazole ring. The structure of compound 4

was further conﬁrmed by its mass spectrum, which showed

a molecular ion peak with an m/z value of 156.7 for (M+H),

which was consistent with the molecular formula

C H N O . The formation of pyrazolo [1, 5-a] pyrimidine

1

3

C

1

13

interpreted by their IR, H and C NMR and LC MS

analyses. The IR spectrums of imine derivative 6a revealed

−

1

the presence of C–N stretch at 1227.70 cm and 1193.72

−

1

cm , respectively. The H NMR spectrum of showed their

characteristic peaks of benzophenonimine and the signal at

6

9 3 2

1

13

compounds 5 a–c were interpreted by their IR, H and

NMR and LC MS analyses. The IR spectrum of compound

a showed a strong band at 3069.21 cm-1 due to the

appearance of –CH stretch of pyrimidine ring whereas the

C=O stretch of ester group was observed at 1700.63 cm-1

C

168.89 ppm in C NMR corresponds to the presence of the

imine carbon in the molecule. The structure of the imine

compound was further conﬁrmed by LC MS. The structures

of the amine derivatives 7 a–c were elucidated by their IR,

5

1

13

–

H NMR and C NMR and LC MS analyses. The IR

1

respectively. In its H NMR spectrum the appearance of two

doublets at δ 7.43 ppm and δ 8.97 ppm conﬁrmed the

presence of pyrimidine protons in the molecule. Also, a

singlet at δ 8.62 ppm conﬁrmed the presence of pyrazole

proton in the molecule. In addition to the above, the signal

spectrum of 7a derivative revealed the presence of amine

group due to the appearance of absorbance bands at

−

1

1545.42 cm for the –N-H bend while the –N-H stretch

−

1

was observed at 3237.19 cm . Also, a strong peak was

−1

observed at 1676.53 cm , which corresponds to the –C=O

1

3

1

at δ 153.62 ppm in the

C NMR corresponds to the

of ester group. The H NMR spectrum of 7a showed the

Med Chem Res

Br

O

1

c

Step -1

DMF-DMA, 110 C, 5h

Br

N

O

Step - 3

Step-4

Step- 2

O

Br

+

N

O

N

NH

AcOH,

72 C,4h

N

Pd dba ,Xanthphos

N

DMF-DMA, AcOH, DMF

NH -NH .H O, 50 C,2h

H

O

Cs CO , 1,4-Dioxane, 110 C, 5h

3

4

O

2

c

O

5

c

6

c

NH

O

NH

R1

NH

Step- 6

R1

Step- 8

R2

Step- 5

R1

R2

O

Step- 7

H

N

HN

N

O

6

N HCl, EtOH, RT, 1 h

N

LiOH

N

O

Cl

O

R1

N

H N

N

O

N

O

HATU

O

N

1

0r-w

OH

7

c

8f-h

O

9

f-h

R1

,5 -Dimethyl

,4,6 -Trichloro

,4 -Dichloro

R2

3

4-Methoxy

4-Fluoro

2

3

Scheme 3 Synthetic route to synthesize of derivatives 10 r–w

characteristic peak viz. the two protons from the aromatic

amine at δ 5.13 ppm. In addition to the above, the signal at δ

The physicochemical characteristics of these inter-

mediates are presented in Table 1.

1

3

1

53.09 ppm in the

C NMR of 7b corresponds to the

The structures of acid derivatives 9 a–h were interpreted

1

13

presence of the pyrazolo pyrimidine junction carbon in the

molecule. The structure of 7b was further conﬁrmed by LC

MS. It showed the molecular ion peak at m/z 283.4 (M+H),

which conforms to its molecular formula.

by their IR, H NMR, and C NMR and LC MS analyses.

The IR spectrum of compound 9e showed a strong band at

−

1

3259.43 cm due to the appearance of –N–H stretch from

−1

the amide and another one at 3083.18 cm due to the

appearance of—O–H stretch from the carboxylic acid. In

addition to that, the presence of two different carbonyl

The formations of amide compounds 8 a–h were inter-

1

13

preted by their IR, H, and C NMR and LC MS analyses.

The IR spectrum of compound 8a showed a strong band at

functional groups in the molecule was identiﬁed due to the

-

1

−1

3

313.13 cm due to the appearance of –NH stretch whereas

appearance of two strong bands at 1683.30 cm

and

−

1

the –C–N stretch was observed at 1330.90 cm-1 respec-

tively. The presence of –C=O of amide group was observed

1599.83 cm , respectively. In its H NMR spectrum the

appearance of a singlet at δ10.36 ppm conﬁrmed the pre-

sence of amide –NH proton. Also, the signals at 163.47

-1

1

by the presence of a strong band at 1667.94 cm . In its H

1

3

NMR spectrum the appearance of a singlet at δ 10.36 ppm

(amide –C=O) and 163.58 (acid –C=O) in the C NMR

signals corresponds to the presence of two different car-

bonyl functional groups in the molecule. The structure of 9e

was further conﬁrmed by LC MS. It showed the molecular

ion peak at m/z 395.3 (M+H), which conforms to its

molecular formula.

1

3

conﬁrmed the presence of amide –NH proton. Also, the

NMR signals at δ 162.62 (amide –C=O) and 164.77 ppm

ester –C=O) corresponds to the presence of two different

carbonyl functional groups in the molecule. The structure of

a was further conﬁrmed by LC MS. It showed the mole-

C

(

8

cular ion peak at m/z 459.3 (M+H), which conforms to its

molecular formula.

The physicochemical characteristics of newly synthe-

sized compounds are presented in Table 2.

Med Chem Res

Table 1 Physicochemical characteristics of substituted derivatives (8a–h)

a

Compound

R1

MF / M.Wt

23 16 4 4 3

C H F N O / 472.40

Yield (%)

80

MP (°C)

8

a

188.1–189.2

F

CF

3

F

O

F

O

H N

2

O

N

H

N

Cl

N

O

8

b

C

22

H15Cl

2

FN

O

4 3

/ 473.29

82

198.3–199.2

Cl

O

Cl

F

Cl

O

N

H

N

O

8

c

C

22

H

15

F

3

N

4

O

3

/ 440.39

81

80

206.6–207.7

218.7–219.6

F

O

F

Cl

O

N

F

H

N

O

8

d

22

H16Cl

2

N

4

O

3

/ 455.30

Cl

O

Cl

H N

2

Cl

N

O

N

H

N

O

8

e

C

22

H

16

F

2

N

4

O

3

/ 422.39

79

81

202.4–203.3

255.4–256.6

F

O

N

H

Cl

F

N

O

f

22

H16Cl

2

N

4

O

3

/ 455.30

Cl

NH₂

Cl

O

Cl

O

NH

N

O

8

g

C

24 22 4

H N O

3

/ 414.47

83

212.0–212.9

O

NH

Cl

N

O

Med Chem Res

Table 1 continued

a

Compound

R1

MF / M.Wt

Yield (%)

78

MP (°C)

8

h

C

22

H15Cl

3

N

4

O

3

/ 489.75

220.3–221.4

Cl

O

Cl

NH

Cl

O

N

O

Table 2 Physicochemical characteristics of substituted derivatives (9 a–h)

a

Compound

R1

MF/M. Wt

Yield (%)

MP (°C)

9a

9b

9c

C

21

H

12

F

4

N

4

O

3

/ 444.35

83

85

83

233.4–234.2

232.5–233.7

246.0–247.1

F

O

F

O

F

N

F

N

H

N

O

OH

O

20

11Cl

2

FN

4

O

3

/ 445.24

F

O

Cl

N

H

N

O

OH

O

20

11

F

N

3 4

O

3

/ 412.33

F

O

F

N

H

N

F

N

O

OH

O

9

d

e

C

20

H

12Cl

2

N

4

O

3

/ 427.25

84

81

258.1–259.2

261.3–262.5

O

Cl

N

H

N

O

OH

O

20 12 2 4 3

H F N O / 394.34

O

F

N

H

N

F

N

OH

O

9

f

C

20

H12Cl

2

N

O

4 3

/ 427.25

80

Cl

HN

O

N

HN

O

N

O

N

O

OH

O

Med Chem Res

Table 2 continued

2

83.4–284.5

a

Compound

R1

R2

MF/M. Wt

C H

Yield (%)

81

MP (°C)

9

g

22

18

N

4

3

O / 386.41

274.9–276.0

HN

O

N

HN

O

N

O

OH

O

9

h

C

20

H11Cl

3 4 3

N O / 461.69

80

284.9–286.1

Cl

HN

O

HN

O

N

O

OH

O

a

Melting point of compounds at their decomposition

The structures of compounds 10 a–w were interpreted by

Anticancer evaluation

1

13

their IR, H NMR, and C NMR and LC MS analyses. The

IR spectrum of 10d revealed the presence of –C=O of amide

group from the benzene attached due to the appearance of

absorbance bands at 1667.24 cm⁻, while that of –C=O of

All compounds were screened for their in vitro anti-cancer

activity against representative human cervical cancer cell

line called HeLa. Cisplatin was used as a reference

standard. The data generated from this study in Table 4

showed that some of the target compounds exhibit good

potency in inhibiting the growth of HeLa cell line.

Compounds 10f, 10k, 10q, 10u, and 10w were showed

good anti proliferative activity against HeLa cell line.

Interestingly, among these compounds, the in-vitro

anticancer activity of compounds 10q, 10u, and

10w are superior to the marketed anticancer drug cispla-

tin. However, some of the synthesized compounds in this

study showed lower levels of anticancer activity than

cisplatin.

1

amide group from the –N–CH attached was observed at

2

−1

1

627.55 cm , respectively. The H NMR spectrum of 10d

showed doublet at δ 4.52–4.53 ppm, for two protons which

correspond to –N–CH – from the molecule. Also, appear-

2

ance of a triplet at δ 8.3 ppm corresponds to –NH proton of

the amide attached to the –N–CH – from the molecule. In

2

addition to the above values, appearance of a singlet at δ

0.31 ppm corresponds to the –NH proton of the amide,

which attached to the benzene ring from the molecule. The

1

signals at δ 161.57 ppm (amide –C=O attached to –N–CH )

2

1

3

and δ 164.76 ppm (amide –C=O attached to benzyl) in

C

NMR corresponds to the presence of two different carbonyl

functional groups in the molecule and also a signal at δ

The anticancer activity of these novel compounds 10a–

w suggested that introduction of the ﬂuoro group in the

para position to the benzyl ring increased the anticancer

activity when compared to the methoxy substituted com-

pounds. Similar observation was found when chloro group

was present in the ortho position of the phenethylamine

ring compared to the methoxy and ﬂuoro group in the para

position of the benzyl ring.

4

1.85 ppm conﬁrms the presence of –N–CH group The

2 .

structure of 10d was further conﬁrmed by LC MS. It showed

the molecular ion peak at m/z 564.2 (M+H), which con-

forms to its molecular formula.

The physicochemical characteristics of newly synthe-

sized compounds are presented in Table 3.

Med Chem Res

Table 3 Physicochemical characteristics of derivatives (10 a–w)

Compound R2

a

R

1

MF/M. Wt

Yield (%)

81

MP (°C)

1

0a

C

28

H18ClF

4

N

5

O

2

/ 567.93

179.1–180.5

F

R1

F

Cl

O

N

H

F

N

F

N

H

N

O

R2

1

0b

0c

0d

C

29

28

H

21

F

4

N

5

O

3

/ 563.52

/ 551.48

83

85

83

157.3–158.4

161.9–163.2

184.1–185.3

F

O

18

5 5 2

F N O

F

20Cl

17Cl

2

3

5 3

FN O / 564.41

Cl

O

Cl

1

0e

0f

C

27

H

F

2

N

5

O

2

/ 552.37

/ 568.83

/ 535.92

88

84

174.8–176.1

185.2–186.6

Cl

F

27

FN

5

O

2

Cl

1

0g

0h

C

27

H17ClF

3

N

5

2

82

84

195.4–196.7

235.1–235.9

F

28

H

20

F

3

N

5

O

3

/ 531.50

/ 519.46

O

1

0i

C

27

H

17

4

N

5

O

2

81

252.4–253.9

F

Med Chem Res

Table 3 continued

a

Compound

R

1

R2

MF/M. Wt

Yield (%)

84

MP (°C)

1

0j

C

27

H18Cl

3

N

5

O

2

/ 550.84

194.2–195.4

R1

Cl

O

N

H

N

Cl

N

H

N

Cl

O

R2

1

0k

C

27

H18Cl

2

FN

5

O

2

/ 534.38

86

188.2–189.1

F

Cl

1

0l

C

28

H

21Cl

2

N

5

O

3

/ 546.42

88

83

207.1–208.4

212.6–213.8

Cl

F

O

1

0m

28

H

21

F

2

N

5

O

3

/ 513.51

F

1

0n

0o

C

27

H

18ClF

2

N

5

O

2

/ 517.93

80

76

217.4–218.8

232.1–233.3

Cl

F

1

27

H17Cl

2

F

2

N

5

O

2

/ 552.37

Cl

1

0p

C

27

H26Cl

2

N

6

O

3

/ 553.45

87

227.2–228.3

Cl

N

Cl

O

1

0q

0r

C

28

H

20Cl

3

N

5

O

2

/ 564.86

78

83

198.2–199.1

257.2–258.7

Cl

30

27 5 3

H N O / 505.58

R1

O

NH

O

N

H

N

O

R2

Med Chem Res

Table 3 continued

a

Compound

R

1

R2

MF/M. Wt

Yield (%)

80

MP (°C)

1

0s

C

29

H

24FN

5

O

2

/ 493.55

268.4–269.8

274.2–275.5

258.6–259.8

306.9–307.8

313.5–314.6

F

0t

28

20Cl

17Cl

21Cl

18Cl

3

N

5

O

3

/ 580.86

79

84

77

76

Cl

O

0u

0v

0w

27

3

FN

5

O

2

/ 568.83

F

28

2

N

5

O

3

/ 546.42

Cl

O

27

2

FN

5

O

2

/ 534.38

Cl

F

a

Melting point of compounds at their decomposition

Structure–activity relationship

lesser antiproliferative activity compared to the less elec-

tronegative chlorine.

The results from the antiproliferative assay showed that at

least one compound from three sets of acids were potent

against HeLa cell line. The compound 10f from the ﬁrst set

contains a ﬂuorine atom in the para position with respect to

amide group in the benzene ring. The compounds 10k and

Conclusion

1

0q from the second set contains no ﬂuorine atom with

A series of 23 novel substituted pyrazolo [1, 5-a] pyrimidine

amide derivatives have been designed and synthesized

using a linear mode multistep synthesis. The synthesized

respect to amide group in the benzene ring. In the same

way, the compounds 10u and 10w from the third set also

contains no ﬂuorine atom with respect to amide group in the

benzene ring, wherein the amide group was placed in para

position with respect to the pyrazolo [1,5-a] pyrimidine

pharmacophore against ortho position in other two sets of

compounds.

The above results gave us an insight to the positioning of

halogen atoms in either of the benzene rings of amides for

getting better potency. All the active compounds contain

minimum of three halogen atoms. We can conclude that the

positioning of more electronegative ﬂuorine gave slightly

1

13

compounds were characterized by H NMR, C NMR,

electrospray ionisation mass spectrometry and infrared

analyses. These new compounds were subsequently

screened for their in vitro antiproliferative activity by MTT

assay. Out of these 23 derivatives synthesized in the current

study, compounds 10q, 10u, and 10w showed good antic-

ancer activity against HeLa cell line. Furthermore, all three

of these compounds are superior with growth inhibition

(IC ) of 10 µM when compared to the marketed anticancer

5

0

drug cis-platin (17.83 µM).

Med Chem Res

Table 4 Anticancer activity of ﬁnal derivatives (10 a–w)

Table 4 continued

Percentage growth inhibition in HeLa cervical cell line

a, b

Compound Concentration

µM)

O.D.

at 492 inhibition

nm

% of growth IC50 (µM)

a, b

Compound Concentration

µM)

O.D.

at 492 inhibition

nm

% of growth IC50 (µM)

(

observed

c

1

0a

0b

0c

0d

0e

0f

10

0.781

0.721

0.681

0.742

0.714

0.618

0.800

0.788

0.784

1.26

2.83

7.09

2.39

3.23

7.41

0.28

1.34

ND

1

0p

0q

0r

10

0.688

0.654

7.27

7.88

39.9 ± 3.4

2

3

0

2

3

0

0.638 12.90

0.236 61.85

0.220 64.64

0.211 67.41

0.543 26.81

0.490 30.98

0.464 25.16

10

51.6 ± 2.8

10

9.1 ± 0.80

29.8 ± 2.4

48.9 ± 3.7

28.7 ± 2.3

8.7 ± 0.76

27.8 ± 2.1

9.6 ± 0.8

2

3

0

2

3

0

c

10

ND

10

2

3

0

2

3

0

10

0.562 24.25

0.428 39.71

0.416 32.90

0.489 34.09

0.431 39.29

0.419 32.41

0.406 40.97

0.386 45.63

0.339 50.48

23.8 ± 1.5

22.6 ± 1.8

10.7 ± 0.9

48.4 ± 3.1

32.6 ± 2.7

24.9 ± 2.1

20.9 ± 1.7

10.3 ± 0.9

44.3 ± 3.1

43.6 ± 2.6

41.1 ± 3.3

31.1 ± 2.5

0s

0t

10

0.739

0.707

0.617

0.779

0.40

0.42

0.48

4.98

2

3

0

2

3

0

10

2

3

0

2

3

0

0.623 12.25

0.421 32.09

0.368 50.40

0.346 51.26

0.317 54.67

10

0u

0v

0w

10

2

3

0

2

3

0

0g

0h

0i

10

0.680

0.646

8.35

9.01

10

0.742

7.68

2

3

0

2

3

0

0.626 11.83

0.423 31.77

0.241 67.52

0.225 68.30

0.216 65.16

0.512 32.34

0.484 41.69

0.401 50.32

0.630 11.61

0.782 5.39

10

2

3

0

0.626 11.83

0.424 31.61

0.552 25.60

0.418 41.12

0.416 32.90

0.552 25.60

0.418 41.12

0.406 34.51

0.402 45.82

0.382 50.28

0.341 56.93

2

3

0

10

Cis-platin 10

17.8 ± 1.4

2

3

0

2

3

0

0j

10

a

Values are averages of three independent experiments, SD < 10%

IC 50—is the concentration of compound required to inhibit the cell

2

3

0

b

growth by 50% compared to an untreated control. The values were

determined from logarithmic concentration—inhibitions curves (ten

points) and are given as means of at least three separate experiments

0k

0l

10

2

3

0

c

ND—Not Determined

10

0.710

0.680

0.618

0.742

0.710

0.620

0.691

0.683

0.641

4.31

4.22

0.32

2.56

1.69

9.03

6.87

3.80

5.38

2

3

0

0m

0n

0o

10

The results of our in-vitro anticancer studies revealed that

majority of these derivatives are very potent against HeLa

cervical cancer cell line. Hence, further structure–activity

relationship studies on these compounds are in progress in

our laboratory.

2

3

0

10

2

3

0

Acknowledgements We would like to thank the Management Team

at Anthem Biosciences Pvt. Ltd., Bangalore, India, for their valuable

support and allocation of proper resources to allow for the completion

of this work. We would also like to thank the Analytical Chemistry

Team at the Department of Analytical Chemistry, Anthem

10

0.538 27.49

0.484 31.83

0.463 25.32

2

3

0

Med Chem Res

Biosciences, Bangalore, India, for carried out all the analytical work

mentioned in this study. Finally, we would like to thank the Molecular

Biology Team at the Maratha Mandal Institute of Technology, Bela-

gavi, Karnataka, India, for conducting the anti-proliferative studies by

MTT assay.

(2009) Identiﬁcation of pyrazolo [1, 5-a] pyrimidine-3-

carboxylates as B-Raf kinase inhibitors. Bioorg Med Chem Lett

19:2735–2738

Gouhar RS, Fathalla OA, Abd El-Karim SS (2013) Synthesis and

anticancer screening of some novel substituted pyrazole deriva-

tives. Der Pharma Chemica 5(6):225–233

Hardtmann GE, Koletar G, Pﬁster OR, Gogerty JH, Iorio LC (1975)

Synthesis and biological evaluation of some 10-substituted -2, 3-

dihydroimidazo [2, 1-b] quinazolin-5[10H]-ones, a new class of

bronchodilators. J Med Chem 18(5):447–453

Compliance with Ethical Standards

Conﬂict of interests The authors declare no competing interests.

Hartwig JF, Motoi K, Hauck SI, Shaughnessy KH, Alcazar- Roman

LM (1999) Room- temperature palladium catalyzed amination of

aryl bromides and chlorides and extended scope of aromatic C- N

bond formation with a commercial ligand. J Org Chem 64

References

(

15):5575 –5580

Ali HI, Fujita T, Akaho E, Nagamatsu T (2010) A comparative study

of autodock and PMF scoring perform ances, and SAR of 2-

substituted pyrazolotriazolopyrimidines and 4-substituted pyr-

azolopyrimidines as potent xanthine oxidase inhibitors. J Comput

Aided Mol Des 24(1):57–75

Aly AA (2006) Synthesis of polyfunctionally substituted pyr-

azolonaphthyridine, pentaza naphthalene and heptaazaphenan-

threne derivatives. Phosphorus Sulfur Silicon Relat Elem 181

Hillebrand S, Tsuchiya T, Hoffman S, Cristau P, Wasnaire P, Seitz T,

Benting J, Wachendorff- Neumann U, Schmidt PJ (2014)

Piperidine pyrazoles as fungicides. US 20140228404 A1

Kamal El-Dean AM, Elkhawaga AM, Radwan ShM, Ahmed MM

(2009) Synthesis of some pyridotheinopyrazolo pyrimido pyr-

imidine and mercaptomethylpyrazolopyrimidine derivatives.

Phosphorous Sulfur Silicon Relat Elem 184(8):2034–2048

Kim I, Song JH, Park CM, Jeong JW, Kim HR, Ha JR, No Z, Hyun

YL, Cho YS, Kang NS, Jeon DJ (2010) Design, synthesis and

evaluation of 2-aryl-7- (3’, 4’- Dialkoxy phenyl)-pyrazolo [1, 5-a]

pyrimidines as novel PDE -4 inhibitors. Bioorg Med Chem Lett

(

10):2395–2409

Austen MA, John KN, Henri JF, George BA(2001) Qinazoline deri-

vatives and their use as pharmaceuticals.WO2001021596

Bagley MC, Baashen M, Paddock VL, Kipling D, Davis T (2013)

Regiocontrolled synthesis of 3- and 5-amino pyrazoles, pyrazolo

2

0(3):922–926

Ley SV, Thomas AW (2003) Modern synthetic methods for copper-

mediated C (aryl)-O, C (aryl)-N and C (aryl) -S bond formation.

Angew Chem Int Ed 42(44):5400–5449

Louie J, Hartwig JF (1995) Palladium—catalyzed synthesis of aryl

amines from aryl halides. Mechanistic studies lead to

coupling in the absence of tin reagents. Tetrahedron Lett 36

[

4

(

3, 4-d] pyrimidines, pyrazolo [3, 4-b] pyridines and pyrazolo [3,

b] quinolinones as MAPK inhibitors. Tetrahedron 69

39):8429–8438

-

Bakavoli M, Bagherzadeh G, Vaseghifar M, Shiri A, Pordel M,

Mashreghi M, Pordeli P, Araghi M (2010) Molecular iodine

promoted synthesis of new pyrazolo [3, 4-d] pyrimidine deriva-

tives as potential antibacterial agents. Eur J Med Chem 45

(21):3609–3612

Maeda H, Akaike T, Miyamoto Y, Yoshida M (1997) Pyrazolopyr-

imidines as antihyperten sive agents. EP 0759298 A2

Nag S, Mishra A, Batra S (2008) A facile route to the synthesis of

pyrimido [2, 1-b] quina zoline core from the primary allyl amines

afforded from Baylis—Hilman adducts. Tetrahedron 64

(

2):647–650

Chauhan M, Kumar R (2013) Medicinal attributes of pyrazolo [3, 4-d]

pyrimidines: a Review. Bioorg Med Chem 21(18):5657–5668

Chiruvella KK, Kari V, Choudhary B, Nambiar M, Ghanta RG,

Raghavan SC (2008) Methyl angolensate, a natural tetra-

nortriterpenoid induces intrinsic apoptotic pathway in leukemic

cells. FEBS Lett 582(29):4066–4076

Curran KJ, Verheijen JC, Kaplan J, Richard DJ, Toral-Barza L, Hol-

lander I, Lucas J, Ayral–Kaloustian S, Yu K, Zask A (2010)

Pyrazolopyrimidines as highly potent and selective, ATP- com-

petitive inhibitors of the mammalian target of rapamycin

(44):10162–10171

Nitulescu GM, Paunescu H, Draghici C, Missir AV, Coman OA, Fulga

I (2010) Synthesis and pharmacological evaluation of some new

pyrazole derivatives. Farmacia 58(2):190 –197

Oslob JD, Romanowski MJ, Allen DA, Baskaran S, Bui M, Elling RA,

Flanagan WM, Fung AD, Hanan EJ, Harris S, Heumann SA,

Hoch U, Jacobs JW, Lam J, Lawrence CE, McDowell RS,

Nannini MA, Shen W, Silverman JA, Sopko MM, Tangonan BT,

Teague J, Yoburn JC, Yu CH, Zhong M, Zimmerman KM,

O’Brien T, Lew W (2008) Discovery of a potent and selective

Aurora kinase inhibitor. Bioorg Med Chem Lett 18

(

mTOR): Optimization of the 1- substituent. Bioorg Med Chem

Lett 20(4):1440–1444

Dinakaran VS, Bomma B, Srinivasan KK (2012) Fused pyrimidines:

The heterocycle of diverse biological and pharmacological sig-

niﬁcance. Der Pharma Chem 4(1):255 –265

Edmondson JM, Armstrong LS, Martinez AO (1988) A rapid and

simple MTT-based spectro photometric assay for determining

drug sensitivity in monolayer cultures. J Tissue Cult Methods

(17):4880–4884

Prasad KN, Ashok G, Raghu C, Shivamurthy GR, Vijayan P, Ardhya

SM (2005) In vitro cytotoxic properties of Ipomoea aquatic leaf.

Indian J Pharmacol 37(6):397–398

Rashad AE, Hegab MI, Abdel–Megeid RE, Fathalla N, Abdel-Megeid

FME (2009) Synthesis and anti –HSV-1-evaluation of some

pyrazoles and fused pyrazolopyrimidines. Eur J Med Chem 44

1

1:15–17

El-Sherief HA, Mahmoud AM, Ismaiel AA (1997) Studies on the

synthesis and cyclization reactions of 2- (5-Amino-3-Arylpyr-

azol-1-yl)-3-methylquinoxalines. J Chem Res 9:322–323

(8):3285–3292

Ge M, Cline E, Yang L (2006) A general method for the preparation of

Schenone S, Brullo C, Bruno O, Bondavalli F, Mosti L, Maga G,

Crespan E, Carraro F, Manetti F, Tintori C, Botta M (2008)

Synthesis, biological evaluation and docking studies of 4- amino

substituted 1H- pyrazolo [3, 4-d] pyrimidines. Eur J Med Chem

3

-acyl-4-cyano-5-amino- pyrazoles. Tetrahedron Lett 47

(

32):5797–5799

Gonclaves MST, Oliveira-Campos AMF, Rodrigues LM, Proenca

MFRP (2012) Synthesis of 4-Amino- 3, 5- dicyano-arylpyrazoles.

Part 2: Isolation and characterization of by-products. Synth

Commun 42(11):1695–1703

Gopalaswamy A, Ciszewski G, Hu Y, Lee F, Feldberg L,

Frommer E, Kim S, Collins K, Wojciechowicz D, Mallon R

4

3(12):2665–2676

Soliman AMM, Abd El-Aleem M, El-Remaily AA, Sultan AA, Abdel-

Ghany H (2014) Synthesis of some novel imidazopyrazole and

Article Doi

Design, synthesis and anti-cancer evaluation of a novel series of pyrazolo [1, 5-a] pyrimidine substituted diamide derivatives

DOI: 10.1007/s00044-016-1770-0

Source and publish data:

Authors:

Article abstract of DOI:10.1007/s00044-016-1770-0

Full text of DOI:10.1007/s00044-016-1770-0

Products guided by the article

R&D Labs maybe for 1203608-45-0

Relevant to this article

Hot Product