Synthesis of some new pyrazolopyridines, pyrazolothienopyridines, pyrazolopyridothienopyrimidines and pyrazolopyridothienotriazines

Article abstract of DOI:10.1080/10426500307843

Pyrazolo[3,4-b]pyridine derivative 3a was prepared and reacted with methyl iodide to give 4 or 5 depending on reaction conditions. Oxidation of 3a with iodine produced the corresponding disulphide derivative 6, whereas oxidation with KMnO₄ gave the corresponding oxo derivative 7. Oxidation of 4 afforded the corresponding sulphone derivative 8, which on boiling in NaOH solution gave 7. The reaction of compound 3a with chloroacetonitrile, ethyl chloroacetate, phenacyl bromide, and chloroacetanilide afforded 9a,b, 11, and 12 respectively. Cyclication of the products 9a,b, 11, and 12 yielded 10a,b, 13, and 14 respectively. The reaction of compound 14 with ethyl orthoformate, nitrous acid, acetic anhydride, benzaldehyde, urea, CS₂, and phenyl isothiocyanate afforded compounds 15-21 respectively.

Full text of DOI:10.1080/10426500307843

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Synthesis of Some New Pyrazolopyridines,
Pyrazolothienopyridines,
Pyrazolopyridothienopyrimidines and
Pyrazolopyridothienotriazines
A.-B. A. G. Ghattas a , A. Khodairy a , M. A. Abd-Rahman a & S. Younes a
a Sohag, Egypt
Published online: 27 Oct 2010.
To cite this article: A.-B. A. G. Ghattas , A. Khodairy , M. A. Abd-Rahman & S. Younes (2003) Synthesis of Some New
Pyrazolopyridines, Pyrazolothienopyridines, Pyrazolopyridothienopyrimidines and Pyrazolopyridothienotriazines, Phosphorus,
Sulfur, and Silicon and the Related Elements, 178:8, 1781-1794, DOI: 10.1080/10426500307843
To link to this article: http://dx.doi.org/10.1080/10426500307843
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Phosphorus, Sulfur, and Silicon, 178:1781–1794, 2003
ꢀC
Copyright Taylor & Francis Inc.
ISSN: 1042-6507 print
DOI: 10.1080/10426500390221113
SYNTHESIS OF SOME NEW PYRAZOLOPYRIDINES,
PYRAZOLOTHIENOPYRIDINES,
PYRAZOLOPYRIDOTHIENOPYRIMIDINES
AND PYRAZOLOPYRIDOTHIENOTRIAZINES
A.-B. A. G. Ghattas, A. Khodairy, M. A. Abd-Rahman,
and S. Younes
Sohag, Egypt
(Received December 1, 2002; accepted March 14, 2003)
Pyrazolo[3,4-b]pyridine derivative 3a was prepared and reacted with
methyl iodide to give 4 or 5 depending on reaction conditions. Ox-
idation of 3a with iodine produced the corresponding disulphide
derivative 6, whereas oxidation with KMnO4 gave the correspond-
ing oxo derivative 7. Oxidation of 4 afforded the corresponding sul-
phone derivative 8, which on boiling in NaOH solution gave 7.
The reaction of compound 3a with chloroacetonitrile, ethyl chloroac-
etate, phenacyl bromide, and chloroacetanilide afforded 9a,b, 11,
and 12 respectively. Cyclication of the products 9a,b, 11, and 12
yielded 10a,b, 13, and 14 respectively. The reaction of compound
14 with ethyl orthoformate, nitrous acid, acetic anhydride, benzalde-
hyde, urea, CS2, and phenyl isothiocyanate afforded compounds 15–21
respectively.
Keywords: Pyrazolopyridines; pyrazolopyridothienopyrimidines; pyra-
zolopyridothienotriazines; pyrazolothienopyridines
It has been reported that thieno[2,3-b]pyridine1–3 derivatives possess
good antibacterial,4–6 antihypertensive,7 and gonadotropin-releasing
hormone antagonizing activity.8,9 Pyridothienopyrimidine derivatives
have been used as analgesics,10 antipyritics,11 and antiinflamma-
tories.12 Also, some pyridothienotriazines exhibit antianaphylactic13
and antiallergic14 activity. This prompted us to synthesize the ti-
tle compounds searching for better pharmacological and biological
properties.
Address correspondence to A.-B. A. G. Ghattas, Chemistry Department, Faculty of
Science, Sohag 82524, Egypt. E-mail: sabry youns@yahoo.com
1781

1782
A.-B. A. G. Ghattas et al.
RESULTS AND DISCUSSION
4-Aryl-5-cyano-6-mercapto-3-oxo-1-phenyl-1,2,3-trihydropyrazolo[3,4-
b]-pyridines 3a–d were synthesized from the reaction of compound 115
with arylidenecyanothioacetamide or by the reaction of 4-arylidene-1-
phenyl-3,5-pyrazolidinediones 2a–d16 with cyanothioacetamide.
SCHEME 1 Ar; a, Ph; b, chlorophenyl; c, flourophenyl; d, Thienyl.
P
P
Methylation of compound 3a with methyl iodide (1:1 molar ratio)
in an alkaline medium afforded 5-cyano-1,4-diphenyl-6-methylthio-3-
oxo-1,2,3-trihydropyrazolo[3,4-b]pyridine (4), but when the reaction is
carried out using 2 mmol of methyl iodide (1:2 molar ratio), the prod-
uct is identified as 5-cyano-1,4-diphenyl-2-methyl-6-methylthio-3-oxo-
1,2,3-trihydropyrazolo[3,4-b]pyridine (5).
SCHEME 2

Synthesis of Some New Pyrazolopyridines, Pyrazolothienopyridines
1783
Oxidation of compound 3a with iodine in an alkaline medium gave
the corresponding disulphide derivative 6, whereas oxidation with
potassium permanganate in an acidic medium afforded 5-cyano-1,4-
diphenyl-3,6-dioxo-1,2,3-trihydropyrazolo[3,4-b]pyridine (7).
SCHEME 3
Oxidation of compound 4 with potassium permanganate in an acidic
medium afforded the corresponding sulphone derivative 8, which on
hydrolysis with 10% sodium hydroxide solution afforded a compound
identical in all respects with compound 7.
SCHEME 4
Compound 3a was used as starting material for the synthe-
sis of thienopyridines. Thus, the reaction of compound 3a with

1784
A.-B. A. G. Ghattas et al.
chloroacetonitrile or ethyl chloroacetate in ethanol containing
sodium acetate, gave the corresponding 2-(5-cyano-3-oxo-1,4-diphe-
nyl-1,2,3-trihydropyrazolo[3,4-b]pyridin-6-ylthio)acetonitrile (9a) and
ethyl[5-cyano-3-oxo-1,4-diphenyl-1,2,3-trihydropyrazolo[3,4-b]pyridin-
6-ylthio]acetate (10a). On refluxing of these compounds in ethanol in
the presence of catalytic amount of sodium ethoxide, they underwent
intramolecular Thorpe-Ziegler cyclization to furnish the correspo-
nding 5-amino-6-cyano-3-oxo-1,4-diphenyl-1,2,3-trihydropyrazolo[3,4-
b]thieno[3,2-e]pyridine (9b) and 5-amino-6-carbethoxy-1,4-diphenyl-
3-oxo-1,2,3-trihydropyrazolo[3,4-b]thieno[3,2-e]pyridine (10b). The
latter compounds also were synthesized via direct interaction of
compound 3a with the appropriate chloro compound in the presence of
sodium ethoxide.
SCHEME 5
Similarly, the pyrazolopyridine derivative 3a reacted with
phenacyl bromide or N-chloroacetanilide in presence of sodium
acetate to give 5-cyano-1,4-diphenyl-3-oxo-6-phenacylthio)-1,2,3-
trihydropyrazolo[3,4-b]pyridine (11) and 5-cyano-1,4-diphenyl-3-oxo-6-
acetanilidethio-1,2,3-trihydropyrazolo[3,4-b]pyridine (13) respectively.
When the above reaction was carried out using sodium ethoxide, 5-
amino-1,4-diphenyl-3-oxo-6-benzoyl-1,2,3-trihydropyrazolo[3,4-b]thie-
no[3,2-e]-pyridine (12), and 5-amino-1,4-diphenyl-3-oxo-6-phenylcar-
bamoyl-1,2,3-trihydro-pyrazolo[3,4-b]-thieno[3,2-e]pyridine (14) were

Synthesis of Some New Pyrazolopyridines, Pyrazolothienopyridines
1785
produced respectively. The latter compounds were obtained also upon
refluxing of compounds 11 and 13 with sodium ethoxide in ethanol.
SCHEME 6
The cyclocondensation of compound 14 with ethyl orthoformate by
refluxing in acetic anhydride led to 1,4,7-triphenyl-2,3,7,8-tetrahy-
dro-1H-pyrazolo-[4ꢁꢁ,3ꢁꢁ:-5ꢁ,6ꢁ ]pyrido[3ꢁ,2ꢁ:4,5]thieno[3,2-d]pyrimidine-
3,8-dione 15. 3,7,10-Triphenyl-4,7,8,9-tetrahydro-3H-pyrazolo-[4ꢁꢁ,3ꢁꢁ:
5ꢁ,6ꢁ]pyrido[3ꢁ,2ꢁ:4,5]thieno[3,2-d] [1,2,3]triazine 4,9-dione 16 was obtai-
ned upon treatment of compound 14 with nitrous acid.
When compond 14 was refluxed in acetic anhydride, 6-methyl-
1,4,7-triphenyl-2,3,7,8-tetrahydro-1H-pyrazolo[4ꢁꢁ ,3ꢁꢁ :5ꢁ,6ꢁ]pyrido[3ꢁ,2ꢁ :
4,5]thieno[3,2-d]pyrimidine 3,8-dione (17) was obtained.
Treatment of compound 14 with benzaldehyde in boiling acetic acid
afforded 1,4,6,7-tetraphenyl-2,3,5,6,7,8-hexahydro-1H-pyrazolo[4ꢁꢁ,3ꢁꢁ:
5ꢁ,6ꢁ]pyrido[3ꢁ,2ꢁ:4,5] thieno[3,2-d]pyrimidine-3,8-dione (18).

1786
A.-B. A. G. Ghattas et al.
SCHEME 7
SCHEME 8
SCHEME 9
The reaction of compound 14 with urea in boiling decalin
led to the formation of 1,4,7-triphenyl-2,3,5,6,7,8-hexahydro-1H-
pyrazolo[4ꢁꢁ ,3ꢁꢁ :5ꢁ,6ꢁ ]pyrido[3ꢁ,2ꢁ:4,5]thieno[3,2-d]pyrimidine-3,6,8-tri-
one (19). The thiono analogue 1,4,7-triphenyl-6-thioxo-2,3,5,6,7,8-
hexahydro-1H-pyrazolo[4ꢁꢁ,3ꢁꢁ :5ꢁ,6ꢁ ]pyrido[3ꢁ,2ꢁ:4,5]thieno-[3,2-d]pyri-
midine-3,8-dione (20) was obtained by refluxing compound 14 with
carbon disulfide in pyridine.

Synthesis of Some New Pyrazolopyridines, Pyrazolothienopyridines
1787
SCHEME 10
1,4,7-Triphenyl-6-aminophenyl-2,3,5,6,7,8-hexahydro-1H-pyrazolo-
[4ꢁꢁ,3ꢁꢁ:5ꢁ,6ꢁ]pyrido[3ꢁ,2ꢁ:4,5]thieno[3,2-d]pyrimidine-3,8-dione (21) was
obtained via the reaction of compound 14 with phenyl isothiocyanate
in pyridine.
SCHEME 11
EXPERIMENTAL
All melting points were determined on a Koffler melting points appa-
ratus and are uncorrected. IR spectra were obtained on a Nicolet 710
FT-IR spectrometer. H-NMR spectra were recorded on a Varian EM 360
at 60 MHz using TMS as an internal reference. Elemental analyses
were carried out with an elemental analyzer model 240 C. Satisfactory
microanalysis (C 0.4, H 0.4, N 0.3%) were obtained for all newly
prepared compounds.

1788
A.-B. A. G. Ghattas et al.
Synthesis of Compounds 3a–d
Method A: From 1-phenyl-3,5-pyrazolidinedione (1): A mixture of
1-phenyl-3,5-pyrazolidinedione 1 (0.01 mmol, 1.76 g), the appropri-
ate arylidenecyanothioacetamide (0.01 mmol), and catalytic amount of
piperidine was refluxed in dioxane (20 mL) for 2 h, the formed pre-
cipitate was recrystallized from appropriate solvent to give compounds
3a–d (cf. Table I).
Method B: From 4-arylidene-1-phenyl-3,5-pyrazolidinediones (2a–d):
A mixture of the appropriate arylidene derivative 2a–d (0.01 mmol),
cyanothioacetamide (0.01 mmol), and catalytic amount of piperidine
was refluxed in ethanol (30 mL) for 2 h, the solid that formed was
collected and recrystallized from appropriate solvent to give compounds
3a–d (cf. Table I).
Synthesis of 5-cyano-1,4-diphenyl-6-methylthio-3-oxo-1,2,3-trihydro-
pyrazolo[3,4-b]pyridine (4): A mixture of compound 3a (0.005 mmol,
1.72 g) in ethanol (20 mL), methyl iodide (0.005 mmol, 0.15 mL), and
sodium hydroxide solution (0.005 mmol, 0.2 g in 5 mL water) were
added. The reaction mixture was stirred at room temperature for 2 h,
the precipitate was collected, washed with water, and recrystallized
from ethanol to give compound 4 (cf. Table I).
Synthesis of 5-cyano-1,4-diphenyl-2-methyl-6-methylthio-3-oxo-1,2,
3-trihydropyrazolo[3,4-b]pyridine (5): A mixture of compound 3a
(0.005 mmol, 1.72 g) in ethanol (20 mL), methyl iodide (0.01 mmol,
0.3 mL), and sodium hydroxide solution (0.01 mmol, 0.4 g in 5 mL wa-
ter) were added. The reaction mixture was stirred at room temperature
for 2 h, the precipitate was collected, washed with water, and recrystal-
lized from ethanol to give compound 5 (cf. Table I).
Synthesis of (5-cyano-3-oxo-1,4-diphenyl-2,3-dihydro-1H-pyrazolo[3,
4-b]-pyridin-6-ylthio)-3-oxo-1,4-diphenyl-2,3-dihydro-1H-pyrazolo[3,4-
b]pyridine (6): A solution of iodine (0.005 mmol, 0.32 g) in potassium
iodide solution (0.005 mmol, 0.5 g in 2 mL water) was added to
compound 3a (0.005 mmol, 1.72 g) in 10% sodium hydroxide solution
(20 mL) with stirring at room temperature for 2 h, the precipitate was
collected and recrystallized from methanol to give compound 6 (cf.
Table I).
Synthesis of compounds 5-cyano-1,4-diphenyl-3,6-dioxo-1,2,3-trihy-
dropyrazolo[3,4-b]pyridine (7) and 5-cyano-1,4-diphenyl-2,3-dihydro-
6-methylsulfonyl-3-oxo-1H-pyrazolo[3,4-b]pyridine (8): Potassium per-
manganate solution (0.008 mmol in 1.26 g, 2 mL water) was added
dropwise to compound 3a (0.005 mmol, 1.72 g) or 4 (0.005 mmol, 1.79 g)
in acetic acid (20 mL) with stirring at room temperature for 2 h, the pre-
cipitate was collected and recrystallized from the appropriate solvent
to give the products 7 and 8 respectively (cf. Table I).

1789

1790

1791

1792
A.-B. A. G. Ghattas et al.
Synthesis of compounds 9a, 10a, 11, and 13 (General procedure): A
mixture of compound 3a (0.005 mmol, 1.72 g), (0.005 mmol) from the ap-
propriate chloro compound [chloroacetonitrile (0.31 mL), ethyl chloroac-
etate (0.54 mL), phenacyl bromide (0.93 g), or N-chloroacetanilide (0.85
g)] and sodium acetate (0.05 mmol, 0.41 g) in ethanol (20 mL) was re-
fluxed for 2 h, the precipitate was collected, washed with water, and
recrystallized from the appropriate solvent to give the compounds 9a,
10a, 11, and 13 respectively (cf. Table I).
Synthesis of compounds 9b, 10b, 12, and 14 (General procedure—
Method A): Compound 9a, 10a, 11, or 13 was suspended in sodium
ethoxide solution (0.35 g Na. in 30 mL absolute ethanol) and refluxed for
3 h, the solid that formed after cooling was collected, washed with water,
and recrystallized from the appropriate solvent to give the compounds
9b, 10b, 12, and 14 respectively (cf. Table I).
Synthesis of compounds 9b, 10b, 12, and 14 (General procedure—
Method B): To a suspension of compound 3a (0.005 mmol, 1.72 g) in
sodium ethoxide solution (0.15 g Na. in 30 mL absolute ethanol), the
appropriate chloro compound (0.01 mmol) was added. The reaction mix-
ture was refluxed for 2 h, and was allowed to cool. The precipitate was
collected, washed with water, dried, and recrystallized from the appro-
priate solvent to give the compounds 9b, 10b, 12, and 14 respectively
(cf. Table I).
Synthesis of 1,4,7-triphenyl-2,3,7,8-tetrahydro-1H-pyrazolo[4ꢁꢁ,3ꢁꢁ:
5ꢁ,6ꢁ]pyrido[3ꢁ,2ꢁ:4,5]thieno[3,2-d]pyrimidine-3,8-dione (15): A mixture
of compond 14 (0.003 mmol, 1.43 g) and ethyl orthoformate (0.003 mmol,
0.5 mL) in acetic anhydride (20 mL) was refluxed for 3 h, The solid
that formed was recrystallized from methanol to give compound 15 (cf.
Table I).
Synthesis of 3,7,10-triphenyl-4,7,8,9-tetrahydro-3H-pyrazolo[4ꢁꢁ,3ꢁꢁ:
5ꢁ,6ꢁ]pyrido[3ꢁ,2ꢁ:4,5]thieno[3,2-d][1,2,3]triazine-4,9-dione (16): Sodium
nitrite solution (0.005 mmol, 0.35 g in 5 mL water) was added dropwise
to compound 14 (0.003 mmol, 1.43 g) in conc. H2SO4 (5 mL) and glacial
acetic acid (5 mL) at 0–5◦C with stirring. The solid that formed, washed
with water, dried, and crystallized from ethanol to give compound 16
(cf. Table I).
Synthesis of 6-methyl-1,4,7-triphenyl-2,3,7,8-tetrahydro-1H-pyra-
zolo[4ꢁꢁ,3ꢁꢁ:5ꢁ,6ꢁ]pyrido[3ꢁ,2ꢁ:4,5]thieno[3,2-d]pyrimidine-3,8-dione (17):
Compound 14 (0.003 mmol, 1.43 g) in redistilled acetic anhydride
(20 mL) was refluxed for 8 h. The solid that precipitated after cool-
ing was filtered off, washed with water, dried, and recrystallized from
ethanol to give compound 17 (cf. Table I).
Synthesis of 1,4,6,7-tetraphenyl-2,3,5,6,7,8-hexahydro-1H-pyrazolo-
[4ꢁꢁ,3ꢁꢁ:5ꢁ,6ꢁ]pyrido[3ꢁ,2ꢁ:4,5]thieno[3,2-d]pyrimidine-3,8-dione (18):
A

Synthesis of Some New Pyrazolopyridines, Pyrazolothienopyridines
1793
mixture of compound 14 (0.003 mmol, 1.43 g) and benzaldehyde
(0.003 mmol, 0.32 mL) in glacial acetic acid (15 mL) was refluxed for
3 h, the product was collected and recrystallized from dioxane to give
compound 18 (cf. Table I).
Synthesis of 1,4,7-triphenyl-2,3,5,6,7,8-hexahydro-1H-pyrazolo-
[4ꢁꢁ,3ꢁꢁ:5ꢁ,6ꢁ]pyrido[3ꢁ,2ꢁ:4,5]thieno[3,2-d]pyrimidine-3,6,8-trione (19): A
mixture of compound 14 (0.003 mmol, 1.43 g) and urea (0.003 mmol,
0.18 g) in decalin (30 mL) was refluxed for 4 h, the product was collected
and crystallized from dioxane to give compound 19 (cf. Table I).
Synthesis of 1,4,7-Triphenyl-6-thioxo-2,3,5,6,7,8-hexahydro-1H-pyr-
azolo[4ꢁꢁ,3ꢁꢁ:5ꢁ,6ꢁ]pyrido[3ꢁ,2ꢁ:4,5]thieno[3,2-d]pyrimidine-3,8-dione (20):
A mixture of compound 14 (0.003 mmol, 1.43 g) and CS2 (0.003 mmol,
0.23 mL) in dry pyridine (30 mL), was refluxed for 20 h, the solvent was
removed by evaporation under reduced pressure and the residue was
crystallized from ethanol to give compound 20 (cf. Table I).
Synthesis of 1,4,7-triphenyl-6-phenylamino-2,3,5,6,7,8-hexahydro-
1H-pyrazolo[4ꢁꢁ,3ꢁꢁ :5ꢁ,6ꢁ ]pyrido[3ꢁ,2ꢁ :4,5]thieno[3,2-d]pyrimidine-3,8-
dione (21): A mixture of 14 (0.003 mmol, 1.43 g) and phenyl isothio-
cyanate (0.003 mmol, 0.4 mL) in dry pyridine (30 mL), was refluxed
for 20 h, the solvent was evaporated and the residue was crystallized
from ethanol to give compound 21 (cf. Table I).
REFERENCES
[1] A. E. Abdel-Rahman, E. A. Bakhite, and E. A. Al-Taifi, J. Chinese Chem. Soc., 49,
223 (2002).
[2] E. A. Bakhite, A. E. Abdel-Rahman, O. S. Mohamed, and E. A. Thabet, Pharmazie,
55, 577 (2000).
[3] E. A. Bakhite, A. E. Abdel-Rahman, O. S. Mohamed, and E. A. Thabet, Phosphorus,
Sulfur and Silicon, 166, 149 (2000).
[4] Z. Shraideh and A.-K. Sallal, Biomed. Lett., 54, 233 (1997).
[5] P. M. Gilis, A. Haemers, and W. Bollaeert, Eur. J. Med. Chem., 15, 185 (1980).
[6] J. Bompart, L. Giral, G. Malicorne, and M. Puygerenier, Eur. J. Med. Chem., 22, 139
(1987).
[7] I. Adachi and Y. Hirramatsu, Jap. Pat. 03, 52, 890 (1991); Chem. Abstr., 115, 71573
(1991).
[8] S. Furuya, N. Takeyru, and H. Matsumoto, Jap. Pat. 09, 169, 766 (1997); Chem.
Abstr., 127, 176416 (1997).
[9] S. Furuya, N. Choh, N. Suzuki, and T. Imada, PCT Int. Appl. WO. 000, 00. 493
(2000); Chem. Abstr., 132, 64179 (2000).
[10] C. G. Dave, P. R. Shah, K. C. Dave, and V. J. Patel, J. Indian Chem. Soc., 66, 48
(1989).
[11] E. Bousquent, G. Romero, F. Guerrera, A. Caruso, and M. A. Roxas, Farmaco Ed.
Sci., 40, 869 (1985).
[12] S. Leistner, G. Wagener, M. Guestscharo, and E. Glusa, Pharmazie, 41, 54 (1986).

1794
A.-B. A. G. Ghattas et al.
[13] G. Wagener, S. Leistner, H. Vieweg, U. Krasselt, and J. Prantz, Pharmazie, 48, 514
(1993).
[14] R. D. Youssefyeh, R. E. Brown, J. Wilson, et al., J. Med. Chem., 27, 1639
(1984).
[15] A. Moustafa, A. Sammour, M. Kira, et al., Arch. Pharm., 298(8), 516 (1965).
[16] D. Preliez and B. Arct, Acta Pol. Pharm., 25(2), 207 (1968).