Synthesis of pyrazolo[3,4-b]pyridines using ammonium acetate as green reagent in multi-component reactions

Article abstract of DOI:10.1002/jhet.5570450447

(Chemical Equation Presented) Several new pyrazolo[3,4-b]pyridine derivatives were synthesized by one pot cyclocondensation of the components; 5-amino-3-aryl-1H-phenylpyrazoles, p-substituted benzoylacetonitriles and some aldehydes. The condensations were most effective by using ammonium acetate as the base catalyst; triethylamine was also studied as a catalyst.

Full text of DOI:10.1002/jhet.5570450447

Jul-Aug 2008
1221
Synthesis of Pyrazolo[3,4-b]pyridines Using Ammonium Acetate as
Green Reagent in Multi-component Reactions
Madhukar N. Jachak* Appasaheb B. Avhale, Bhausaheb K. Ghotekar, Dhananjay B. Kendre and
Raghunath B.Toche
Organic Chemistry Research Center, Department of Chemistry, K. R. T. Arts, B. H. Commerce and A. M. Science College, Gangapur Road,
Nashik-422002, (M. S.) India
e-mail: mn_jachak@hotmail.com
Received July 2, 2007
R1
R3
R1
R3
N
O
H
CN
CN
+
N
N
N
N
NH2
O
R2
R2
Several new pyrazolo[3,4-b]pyridine derivatives were synthesized by one pot cyclocondensation of the
components; 5-amino-3-aryl-1H-phenylpyrazoles, p-substituted benzoylacetonitriles and some aldehydes. The
condensations were most effective by using ammonium acetate as the base catalyst; triethylamine was also studied
as a catalyst.
J. Heterocyclic Chem., 45, 1221 (2008).
INTRODUCTION
sized in one pot in which the synthesis of chalcone is not
required. A literature survey showed few reports on the
synthesis of pyrazolo[3,4-b]pyridines using Michael
addition [14,15] however with substitution patterns
different from ours. As 5-amino-3-aryl-1-phenyl-1H-
pyrazole was already in hand [16] we performed the one
pot synthesis of the title compounds. Thus cycloconden-
sation of 5-amino-3-aryl-1-phenyl-1H-pyrazole 1, p-
substituted benzoylacetonitriles 2 and aryl/H aldehydes 3
on fusion in ammonium acetate at 120 °C gave
pyrazolo[3,4-b]pyridine derivatives 4 in 80-85 % yield
(Scheme 1). This reaction did not require any solvent and
the aqueous work up of the reaction allowed for the
isolation of 100 % of the product. During heating, the
acetate ion serves as the base in this condensation reaction
and the condensation products were obtained in pure state
without the need for further purification. Compounds 4
were also synthesized by using solvent and catalyst,
however low yields of products were obtained and further
purification was necessary.
Multi-component reactions (MCRs) are of increasing
importance in organic and medicinal chemistry. MCR
strategies offer significant advantages over conventional
linear type synthesis [1]. Ugi reported a three component
condensation with heterocyclic amine, various aldehydes
and nitriles or isocynate [2] and Tsai et al. reported that
this condensation speeds up in a sealed vessel under
microwave heating [3].
Today chemists are in search of environmentally
friendly reagents to furnish clean reactions with high yield
of a single product and easy to work up. Previously [6] we
have successfully synthesized pyranofused quinolines,
coumarins/pyridones by using cyclic ꢀ-ketoesters and 4-
hydroxy quinoline/coumarin/pyridones with ammonium
acetate. We have also synthesed fused pyrimidines [7] by
fusion of 2-aminoheterocycles and ꢀ-ketoester in
ammonium acetate at 120 °C. The pyrazolo[3,4-b]-
pyridine derivatives show promising biological activities
[8-13]. These reports prompted us to study the synthesis
of pyrazolo[3,4-b]pyridines using multicomponent
reactions.
EXPERIMENTAL
Melting points were determined on a Gallenkamp melting
points apparatus in capillaries and are uncorrected. H NMR
RESULTS AND DISCUSSION
1
spectra were recorded on Varian XL-300 MHz spectrometer and
chemical shifts are expressed in ppm with reference to TMS as
an internal standard. IR spectra were obtained on Shimadzu IR-
408 as potassium bromide pellets unless otherwise stated.
Elemental analyses were determined on Hosli C, H Analyzer.
The reactions were checked with thin layer chromatography
Synthesis of pyrazolo[3,4-b]pyridine derivatives has
been reported by J. Quiroga and coworker [14,15] using
5-amino-3-methyl/phenyl-1-phenyl/H-1H-pyrazole
and
chalcone of benzoylacetonitrile/malanonitrile with
aromatic aldehydes. The title compounds could be synthe-

1222
M. Jachak, A. Avhale, B. Ghotekar, D. Kendre, R. Toche
Vol 45
Scheme 1
R3
R1
O
R1
H
R3
3
Method A:
CN
CN
NH4OAc, 120°C, 20-25 min
+
N
N
N
N
O
N
NH2
Method B: Et3N, EtOH, 1 hr.
R2
R2
2
4a-t
1
Product
Color & Physical State
Yield (%)
(Crystallization Solvent)
Mp (°C)
R1
R2
R3
Method
Method
B
72
A
4a
4b
4c
4d
4e
4f
4g
4h
4i
Cl
Cl
Cl
Cl
Br
Br
Cl
CH3
CH3
Cl
CH3
CH3
CH3
p-FC6H4
p-FC6H4
p-CNC6H4
p-ClC6H4
H
p-FC6H4
p-ClC6H4
C4H3S (2-Thienyl)
C4H3 (Furyl)
C15H10ClN2 (4-{3-(4-
chlorophenyl) pyrazoyl}
p-ClC6H4
p-ClC6H4
p-ClC6H4
p-CNC6H4
p-BrC6H4
p-OMeC6H4
m-OMeC6H4
p-MeC6H4
C6H5
C15H10ClN2 (4-{3-(4-
chlorophenyl) pyrazoyl}
Colorless (DMF)
Colorless (DMF)
Colorless (DMF)
Colorless (DMF)
Colorless (DMF)
Colorless (DMF)
Colorless (DMF)
Colorless (DMF)
Colorless (DMF)
Colorless (DMF)
280-281
284-285
326-327
280-281
235-237
234-235
258-259
221-222
238-239
244-245
82
85
81
79
80
82
81
84
82
83
74
69
66
70
71
69
73
71
Cl
CH3
CH3
CH3
CH3
CH3
CH3
4j
70
4k
4l
Cl
Br
Br
Br
Cl
Br
Br
Br
Br
Cl
Br
Br
Cl
Cl
Br
Cl
Cl
Cl
Br
CH3
Colorless (DMF)
263-264
315-316
302-303
331-332
289-290
245-247
234-235
270-272
245-246
278-279
88
82
86
79
89
83
78
77
88
85
77
73
75
78
76
67
68
72
71
73
Yellow (ethanol /DMF)
Yellow (ethanol /DMF)
Colorless (DMF)
4m
4n
4o
4p
4q
4r
4s
Colorless (DMF)
Yellow (ethanol /DMF)
Yellow (ethanol /DMF)
Yellow (ethanol /DMF)
Yellow (ethanol /DMF)
Colorless (DMF)
4t
using UV light. All Compounds were synthesized by both,
methods A and B.
of triethylamine (1 mL) for one hour. The solid obtained was
collected by filtration, washed with ethanol, dried and
recrystallized from a suitable solvent to furnish the compounds 4
in good yield.
General Procedure Synthesis of 3,4 6-triaryl-1-phenyl-1H-
pyrazolo[3,4-b]pyridine-5-carbonitrile (4).
3,6-Bis(4-chlorophenyl)-4-(4-fluorophenyl)-1-phenyl-1H-
pyrazolo[3,4-b]pyridine-5-carbonitrile (4a). ir: (Potassium
Method-A. A mixture of 5-aminopyrazole 1 (2 mmole),
aroylacetonitrile 2 (2 mmole) and aryl/H aldehyde 3 (2 mmole)
and ammonium acetate (5 mole) was placed in a reaction flask
with a short condenser or vigreaux column attached to the flask.
The reaction mixture was heated in an oil bath at 120° C for 20-
25 minutes (TLC Check). Reaction mixture after cooling was
stirred in 100 mL cold water to remove excess of ammonium
acetate and impurities formed during the reaction. The solid
obtained was collected by filtration washed with water, dried
and recrystallized from a suitable solvent to furnish the
compounds 4 in good yield.
1
bromide): 2221, 1453, 1520, 1166 864, 843, 731cm-1; H nmr:
(CDCl3) ꢀ 7.02-7.50 (m, 9H, Ar-H), 7.62 (d, 2H, J = 8.4 Hz, Ar-
H), 7.76 (d, 2H, J = 8.7 Hz, Ar-H), 7.98 (d, 2H, J = 8.4 Hz, Ar-
H), 8.42 (d, 2H, J = 8.7 Hz, Ar-H); Anal. Calcd. for
C31H17Cl2FN4: C, 69.54; H, 3.20; N, 10.46. Found: C, 69.70; H,
3.45; N, 10.58.
6-(4-Bromophenyl)-3-(4-chlorophenyl)-4-(4-fluorophenyl)-
1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile (4b). ir:
(Potassium bromide): 2223,1453, 1520, 1166 cm-1; 1H nmr:
(CDCl3) ꢀ 7.02-7.63 (m, 11H, Ar-H), 7.74 (d, 2H, J = 8.7 Hz,
Ar-H), 7.94 (d, 2H, J = 8.4 Hz, Ar-H), 8.35 (d, 2H, J = 8.7 Hz,
Ar-H), 8.42 (d, 2H, Ar-H); Anal. Calcd. for C31H17BrClFN4: C,
64.21; H, 2.95; N, 9.66 Found: C, 64.38; H, 2.67; N, 9.79.
Method-B. A mixture of 5-aminopyrazole 1 (2 mmole),
aroylacetonitrile 2 (2 mmole) and aryl/H aldehyde 3 (2 mmole)
was refluxed in ethanol (10 mL) in presence of catalytic amount

Jul-Aug 2008
Synthesis of Pyrazolo[3,4-b]pyridines Using Ammonium Acetate as Green Reagent
1223
6-(4-Bromophenyl)-3-(4-chlorophenyl)-4-(4-cyanophenyl)-
1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile (4c).
ir: (Potassium bromide): 2219, 1453, 1515, 1169 cm-1; 1H
nmr: (DMSO-d6) ꢀ 7.03-7.14 (m, 4H, Ar-H), 7.39-7.74 (m,
8H, Ar-H), 7.89-8.24(m, 5H, Ar-H); Anal. Calcd. for
C32H17BrClN5: C, 65.49; H, 2.92; N, 11.93 Found: C, 65.71;
H, 3.17; N, 12.18.
H), 7.96 (d, 2H, J = 8.4 Hz, Ar-H), 8.29 (d, 2H, J = 7.8 Hz, Ar-
H); Anal. Calcd. for C21H17BrCl2N4: C,62.44; H, 2.87; N,9.40.
Found: C, 62.52; H, 2.91; N, 9.36.
3,6-Bis(4-bromophenyl)-4-(4-chlorophenyl)-1-phenyl-1H-
pyrazolo[3,4-b]pyridine-5-carbonitrile (4l).; ir: (Potassium
1
bromide): 2230,1462, 1520, 1167 cm-1; H nmr: (CDCl3) ꢀ 7.01
(d, 2H, J = 8.7 Hz, Ar-H), 7.11 (d, 2H, J = 8.4 Hz, Ar-H), 7.20
(m, 4H, Ar-H), 7.29 (t, 1H, J = 7.2 Hz, Ar-H), 7.52 (m, 4H, Ar-
H), 7.95 (d, 2H, J = 8.4 Hz, Ar-H), 8.28 (d, 2H, J = 7.8 Hz, Ar-
H); Anal. Calcd. for C21H17Br2ClN4: C,58.11; H, 2.67; N, 8.74.
Found: C, 58.22; H, 2.58; N, 8.70.
3,4,6-Tri(4-chlorophenyl)-1-phenyl-1H-pyrazolo[3,4-b]-
pyridine-5-carbonitrile (4d). ir: (Potassium bromide):
1
2220,1453, 1515, 1169 cm-1; H nmr: (DMSO-d6), ꢀ 7.15-7.74
(m, 11H, Ar-H), 7.84-8.24 (m, 6H, Ar-H); Anal. Calcd. for
C31H17Cl3N4: C,67.47; H, 3.10; N, 10.15 Found: C, 67.65; H,
3.27; N, 10.36.
3-(4-Bromophenyl)-4,6-bis(4-chlorophenyl)-1-phenyl-1H-
pyrazolo[3,4-b]pyridine-5-carbonitrile (4m). ir: (Potassium
1
bromide): 2232,1462, 1512, 1157 cm-1; H nmr: (CDCl3) ꢀ 7.01
3,6-Bis(4-Methylphenyl)-1-phenyl-1H-pyrazolo[3,4-b]-
pyridine-5-carbonitrile (4e). ir: (Potassium bromide):
(d, 2H, J = 8.7 Hz, Ar-H), 7.13 (d, 2H, J = 8.4 Hz, Ar-H), 7.20
(m, 4H, Ar-H), 7.36 (t, 1H, J = 7.2 Hz, ArH), 7.53 (m, 4H, Ar-
H), 7.98 (d, 2H, J = 8.4 Hz, Ar-H), 8.29 (d, 2H, J = 7.8 Hz, Ar-
H); Anal. Calcd. for C21H17BrCl2N4: C, 62.44; H, 2.87; N, 9.40.
Found: C, 62.55; H, 2.92; N, 9.39.
3-(4-Bromophenyl)-6-(4-chlorophenyl)-4-(4-cyanophenyl)-
1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile (4n). ir:
(Potassium bromide): 2230,1462, 1596, 1157 cm-1; 1H nmr:
(CDCl3) ꢀ 7.07 (d, 2H, J = 8.4 Hz, Ar-H), 7.11 (d, 2H, J = 8.7
Hz, Ar-H), 7.30 (t, 1H, Ar-H), 7.41 (d, 2H, J = 8.4 Hz, Ar-H),
7.70 (d, 2H, J = 8.4 Hz, Ar-H), 7.54 (m, 4H, Ar-H), 7.89 (d, 2H,
J = 8.7 Hz, Ar-H), 8.29 (d, 2H, J = 7.8 Hz, Ar-H); Anal. Calcd.
for C32H17BrClN5: C, 65.49; H, 2.92; N, 11.93 Found: C, 65.26;
H, 2.88; N, 11.96.
1
2227,1453, 1519, 1170 cm-1; H nmr: (DMSO-d6) ꢀ 2.54 (s, 6H,
2CH3), 7.39 (m, 5H, Ar-H), 7.55 (m, 2H, Ar-H), 7.95 (m, 2H,
Ar-H), 8.42 (d, 2H, J = 8.4 Hz, Ar-H), 8.83 (s, 1H, C4H); Anal.
Calcd. for C21H17ClN2O2: C,80.97; H, 5.03; N, 13.99 Found: C,
80..98; H, 5.24; N, 14.23.
3,6-Bis(4-Methylphenyl)-4-(4-fluorophenyl)-1-phenyl-1H-
pyrazolo[3,4-b]pyridine-5-carbonitrile (4f). ir: (Potassium
1
bromide): 2224,1453, 1519, 1170 cm-1; H nmr: (CDCl3) ꢀ 2.56
(s, 6H, 2CH3), 7.39-7.51 (m, 9H, Ar-H), 7.55 (m, 2H, Ar-H),
7.74 (d, 2H, J = 8.4 Hz, Ar-H), 7.95 (d, 2H, J = 8.4 Hz, Ar-H),
8.42 (d, 2H, J = 8.6 Hz, Ar-H); Anal. Calcd. for C33H23FN4:
C,80.14; H, 4.69; N, 11.33 Found: C, 80.11; H, 4.67; N, 11.48
4,6-Bis(4-Chlorophenyl)-3-(4-methylphenyl)-1-phenyl-1H-
pyrazolo[3,4-b]pyridine-5-carbonitrile (4g). ir: (Potassium
4,6-Bis(4-bromophenyl)-3-(4-chlorophenyl)-1-phenyl-1H-
pyrazolo[3,4-b]pyridine-5-carbonitrile (4o). ir: (Potassium
1
bromide): 2223,1453, 1519, 1170 cm-1; H nmr: (CDCl3) ꢀ 2.48
1
bromide): 2230,1462, 1596, 1157 cm-1; H nmr: (CDCl3) ꢀ 7.01
(s, 3H, CH3), 7.02-7.63 (m, 11H, Ar-H), 7.74 (d, 2H, J = 8.4 Hz,
Ar-H), 7.94 (d, 2H, J = 8.7 Hz, Ar-H), 8.35 (d, 2H, J = 8.4 Hz,
Ar-H); Anal. Calcd. for C32H20Cl2N4: C,72.32; H, 3.79; N,8.07.
Found: C, 72.5; H, 3.97; N, 8.22.
(d, 2H, J = 8.4 Hz, Ar-H), 7.11 (d, 2H, J = 8.7 Hz, Ar-H), 7.20
(m, 4H, Ar-H), 7.37 (t, 1H, J = 7.2 Hz, Ar-H), 7.52 (m, 4H, Ar-
H), 7.98 (d, 2H, J = 8.7 Hz, Ar-H), 8.28 (d, 2H, J = 7.8 Hz, Ar-
H); Anal. Calcd. for C21H17Br2ClN4: C,58.11; H, 2.67; N, 8.74.
Found: C, 58.30; H, 2.70; N, 8.78.
3,6-Bis(4-Methylphenyl)-1-phenyl-4-thien-2-yl-1H-pyra-
zolo[3,4-b]pyridine-5-carbonitrile (4h). ir: (Potassium
1
bromide): 2219,1453, 1519, 1170 cm-1; H nmr: (CDCl3) ꢀ 2.47
3-(4-Bromophenyl)-6-(4-chlorophenyl)-4-(4-methoxyph-
enyl)-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile (4p).
(s, 6H, 2CH3), 6.99-7.56 (m, 12H, Ar-H), 7.92 (d, 2H, J = 8.4
Hz, Ar-H), 8.32 (d, 2H, J = 8.4 Hz, Ar-H); Anal. Calcd. for
C31H22N4S: C, 77.15; H, 4.59; N,11.61 Found: C, 77.34; H, 4.68;
N,11.68.
1
ir: (Potassium bromide): 2231,1462, 1596, 1157 cm-1; H nmr:
(CDCl3) ꢀ 3.22 (s, 3H, OCH3), 7.04 (d, 2H, J = 8.4 Hz, Ar-H),
7.15 (d, 2H, J = 8.7 Hz, Ar-H), 7.22 (m, 4H, ArH), 7.37 (t, 1H, J
= 7.2 Hz, Ar-H), 7.52 (m, 4H, Ar-H), 7.99 (d, 2H, J = 8.7 Hz,
Ar-H), 8.30 (d, 2H, J = 7.8 Hz, Ar-H); Anal.Calcd. for C32H20
BrClN4O: C, 64.94; H, 3.41; N, 9.47. Found: C, 65.10; H, 3.70;
N, 9.78.
3,6-Bis(4-Methylphenyl)-4-(2-furyl)-1-phenyl-1H-pyra-
zolo[3,4-b]pyridine-5-carbonitrile (4i). ir: (Potassium
1
bromide): 2218,1453, 1519, 1170 cm-1; H nmr: (CDCl3) ꢀ 2.49
(s, 6H, 2CH3), 6.54 (m, 1H, Ar-H), 7.10 (m, 1H, Ar-H), 7.17-
7.55 (m, 8H, Ar-H), 7.67 (d, 2H, J = 8.4 Hz, Ar-H), 7.85 (d, 2H,
J = 8.6 Hz, Ar-H), 8.25 (d, 2H, J = 8.3 Hz, ArH); Anal. Calcd.
for C31H22N4O: C,79.81; H, 4.75; N,12.01 Found: C, 79.94; H,
4.85; N, 12.08.
3-(4-Bromophenyl)-6-(4-chlorophenyl)-4-(3-methoxyph-
enyl)-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile (4q).
1
ir: (Potassium bromide): 2231,1462, 1596, 1157 cm-1; H nmr:
(CDCl3) ꢀ 3.26 (s, 3H, OCH3) 7.06 (d, 2H, J = 8.4 Hz, ArH),
7.17 (d, 2H, J = 8.7 Hz, ArH), 7.23 (m, 4H, ArH), 7.38 (t, 1H, J
= 7.2 Hz, ArH), 7.50 (m, 4H, ArH), 7.99 (d, 2H, J = 8.7 Hz,
ArH), 8.32 (d, 2H, J = 7.8 Hz, ArH); Anal. Calcd. for
C32H20BrClN4O: C, 64.94; H, 3.41; N, 9.47. Found: C, 65.17; H,
3.21; N, 9.17.
3,6-Bis(4-Methylphenyl)-4-[3-(4-chlorophenyl)-1-phenyl-
1H-pyrazol-4-yl]-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile
1
(4j). ir: (Potassium bromide): 2218,1453, 1519, 1170 cm-1; H
nmr: (CDCl3) ꢀ 2.41 (s, 6H, 2CH3), 6.97 (d, 2H, Ar-H), 6.97 (d,
2H, Ar-H), 7.12-7.57 (m, 14H, Ar-H), 7.67 (d, 2H, J = 8.4 Hz,
Ar-H), 7.84 (m, 3H, Ar-H), 8.31 (d, 2H, J = 8.4 Hz, Ar-H); Anal.
Calcd. for C42H29ClN6: C,77.23; H, 4.47; N,12.87 Found: C,
77.43; H, 4.64; N,12.94.
3-(4-Bromophenyl)-6-(4-chlorophenyl)-1-phenyl-4-p-tolyl-
1H-pyrazolo[3,4-b]pyridine-5-carbonitrile (4r). ir: (Potassium
1
bromide): 2238, 1462, 1596, 1157 cm-1; H nmr: (CDCl3) ꢀ 2.9
6-(4-Bromophenyl)-3,4-bis(4-chlorophenyl)-1-phenyl-1H-
pyrazolo[3,4-b]pyridine-5-carbonitrile (4k). ir: (Potassium
(s, 3H, CH3), 7.03 (d, 2H, J = 8.4 Hz, Ar-H), 7.18 (d, 2H, J = 8.7
Hz, Ar-H), 7.25 (m, 4H, Ar-H), 7.40 (t, 1H, J = 7.2 Hz, Ar-H),
7.50 (m, 4H, Ar-H), 7.99 (d, 2H, J = 8.7 Hz, Ar-H), 8.26 (d, 2H,
J = 7.8 Hz, Ar-H); Anal. Calcd. for C32H20BrClN4: C, 66.74; H,
3.50; N, 9.73. Found: C, 66.46; H, 3.21; N, 9.52.
1
bromide): 2214,1453, 1519, 1170 cm-1; H nmr: (CDCl3) ꢀ 7.02
(d, 2H, J = 8.7 Hz, Ar-H), 7.12 (d, 2H, J = 8.4 Hz, Ar-H), 7.21
(m, 4H, Ar-H), 7.36 (t, 1H, J = 7.2 Hz, Ar-H), 7.53 (m, 4H, Ar-

1224
M. Jachak, A. Avhale, B. Ghotekar, D. Kendre, R. Toche
Vol 45
[2] Ugi I.; Pure Appl. Chem. 2001, 73, 187-191.
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1999, 36, 467.
3,6-Bis(4-bromophenyl)-1,4-diphenyl-1H-pyrazolo[3,4-b]-
pyridine-5-carbonitrile (4s). ir: (Potassium bromide): 2236,
1
1462, 1596, 1157 cm-1; H nmr: (CDCl3) ꢀ 7.03 (d, 2H, J = 8.4
Hz, Ar-H), 7.18 (d, 2H, J = 8.7 Hz, Ar-H), 7.25 (m, 4H, Ar-H),
7.40 (t, 1H, J = 7.2 Hz, Ar-H), 7.50 (m, 5H, Ar-H), 7.99 (d, 2H,
J = 8.7 Hz, Ar-H), 8.26 (d, 2H, J = 7.8 Hz, Ar-H); Anal. Calcd.
for C31H18Br2N4: C, 61.41; H, 2.99; N, 9.24. Found: C, 61.31; H,
2.71; N, 9.52.
3-(4-Chlorophenyl-6-(4-Methylphenyl)-4-[3-(4-chlorophenyl)-
1-phenyl-1H-pyrazol-4-yl]-1H-pyrazolo[3,4-b]pyridine-5-
carbonitrile (4t). ir: (Potassium bromide): 2221,1453, 1569,
[7] Toche R.; Ghotekar B.; Kazi M.; Kendre D.; and Jachak M.;
Teterahedrone, 2007, 63, 8157.
[8] Hardy C.; Adv. Heterocyclic Chem. 1984, 36, 343.
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(1968)
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1
1160 cm-1; H nmr: (DMSO-d6) ꢀ 2.41 (s, 6H, 2CH3), 6.97 (d,
2H, Ar-H), 6.97 (d, 2H, Ar-H), 7.12-7.57 (m, 14H, Ar-H), 7.67
(d, 2H, J = 8.4 Hz, Ar-H), 7.84 (m, 3H, Ar-H), 8.31 (d, 2H, J =
8.4 Hz, Ar-H); Anal. Calcd. for C41H26Cl2N6: C,73.11; H, 3.89;
N, 12.48. Found: C, 73.26; H, 3.96; N, 12.64.
Acknowledgement. The authors highly obligated to UGC New
Delhi for financial Support and that of our institute K.T.H.M.
College, Nashik for co-operation shown during the research
work.
[12] Chen Y.; International Patent WO 9534563 Al 1995, Chem.
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Ueda M.; Drug. Dev. Res., 1990, 20, 453.
[14] Quiroga J.; Alvarado M.; Insuasty B.; and Moreno R.; J.
Heterocyclic Chem. 1999, 36, 1311
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