The document describes the preparation and reactions of 6-Aryl-1,5-dihydro-3-phenyl-4H-pyrazolo[4,3-c]pyridin-4-ones. It details a method for synthesizing these compounds from 5-aryl-2-phenylpyrazolo[1,5-c]pyrimidine-7(6H)-thiones using reaction with thiosemicarbazide. These pyrazolo[4,3]pyridines have biological activities including fungicidal, antibacterial, anti-inflammatory, and antiasthmatic. Their structures were elucidated using IR and 1H NMR spectroscopy. The compounds undergo several substitution

1. 1
Preparation and Reactions of 6-Aryl-1,5-dihydro-3-
phenyl-4H-pyrazolo[4,3-c]pyridin-4-ones

2. 2
Preparation of 6-Aryl-1,5-dihydro-3-phenyl-4H-pyrazolo[4,3-c]pyridin-4-ones
In the present study, a new method for the synthesis of 6-Aryl-1,5-dihydro-3-phenyl-4H-
pyrazolo[4,3-c]pyridin-4-ones from 5-aryl-2-phenylpyrazolo[1,5-c]pyrimidine-7(6H)-thiones
has been developed. The latter compounds, which are also useful as starting materials for the
synthesis of some derivatives of the pyrazolo[1,5-c]pyrimidine ring system , were prepared
by
reaction of 1,5-diaryl-4-pentyne-1,3-diones with thiosemicarbazide.
Application and biological activities :-
Pyrazolo[4,3]pyridines have continued to attract interest owing to their structural
relationship to antagonistic purine bases and guanines as well as biological interest . Thus
,some of these compounds show fungicidal and antibactrial ,antiinflammatory, tranquilizing
,and antiasthmatic activities.

3. 3

4. 4
Elcucidation of product by IR and 1HNMR
The IR spectra of the pyrazolopyridones exhibited, besides a strong carbonyl-stretching band in
the region 1713-1740 cm-1, a strong C=N absorption in the range 1621-1632 cm-1 as well as C=C
and NH absorptions . The absence of absorption in their spectra indicates that in the solid state
the lactam form predominates over the lactim one .
The 1HNMR spectra of compound showed a singlet at δ=7.33-7.50 for the H-7 ring proton , in
the almost the same region reported for several pyrazolo[4,3-c]pyridine, and an exchangeable
singlet at δ=13.00-13.30 for the pyrazole proton. Moreover , besides the pyridine ring NH proton
at δ=11.15-11.53, a broad singlet signal (δ=8.46-8.55) which may suggest some contribution of
the enol form was observed .

5. Reactions of 6-Aryl-1,5-dihydro-3-phenyl-4H-pyrazolo[4,3-c]pyridin-4-ones
1- refluxed with phosphorus pentasulifide in dry benzene
5
2-Iodination with iodine monochloride

6. 6
3-Bromination by bromine
4-Nitration bynitric acid and sulfric acids in hot glacial acetic acid

7. 7
5-Nitrosiation by sodium nitrite in hot glacial acetic acid
6-sulfonation by fuming sulfric acid

8. 8
7- Electrophikic substitution (phenylazo) by benzenediazaonium chloride
in the presence of sodium hydroxide

9. 9