الفهرس 
Chemistry of PyridinesOnly 14 pages are availabe for public view
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Abstract
In view of the significant biological activities of pyridine derivatives, the present investigation
deals with the synthesis of some new pyridine derivatives as antimicrobial agents using 4-(
p-chlorophenyl )-3-cyano-6-( p-hydroxyphenyl )-2( 1H ) pyridone (1), as starting material .
Treatment of 4-(p-chlorophenyl)-3-cyano-6-( p-hydroxy
phenyl)-2(1H)-pyridone (1) with POCh- PCls mixture in the presence of
N,N-dimethylaniline gave 2-chloropyridine derivative ( 2 ). Reaction of 2 with hydrazine
hydrate in ethanol produced 1H-3-amino-4-(p-chlorophenyl)-6-(p-hydroxyphenyl)
pyrazolo[3,4-b]pyridine ( 3 ). Also, interaction of 2 with semicarbazide
hydrochloride, thiosemicarb· ·azide and benzo hydrazide afforded 4a,b and 5 ,
respectively. Similarly, 2 reacted with glycine to give 6, which on treatment with acetic
anhydride and sodium acetate gave 7.
2 also, reacted with active methylene reagents such as
ethyl cyanoacetate and malononitrile to yield the respective
pyridine derivatives 8a,b. A similar reaction of 2 with malonic acid afforded 9 ,which underwent
ring closure on heating with thiourea or phenyl thiourea to give 10 a,b, respectively.
Reaction of 2 with sodium azide gave tetrazolo[ 1,5-a ] pyridine derivative (12) , which on
thermolysis in boiling toluene and in the presence of PPh3 afforded 14. In addition, the
triphenylphosphoranylidenearnino group of 14 was readily replaced by amino group on hydrolysis
with aqueous acetic
acid to give 15 .
lH-3-Amino-4-( p-chlorophenyl )-6-( p-hydroxyphenyl )- pyrazolo[3,4-b]pyridine(3) reacted with
phenacyl bromide and a-dicarbonyl compounds such as ethyl pyruvate and diethyl oxalate to give 16 ,
17 and 18, respectively. Treatment of 18 with o-phenylene diarnine and semicarbazide hydrochloride
yielded the respective polycyclic systems 19 and 20 .
A similar treatment of 3 with 13-dicarbonyl compounds
such as acetylacetone , dibenzoylmethane and diethyl makmate afforded 21a,b and 22 , respectively
Furthermore, condensation of 22 with p-chlorobenzaldehyde yielded 23 .
Addition of phenyl isothiocyanate to 3 afforded 24 ,
which reacted with phenacyl bromide yielding 25 . Also , condensation of 3 with p-nitobenzaldehyde
gave 26, which underwent cycloaddition with thioglycolic acid giving 27.
When compound 3 was submitted to react with acrylonitrile in pyridine, cyanoethylation takes
place affording
28 , which on acid hydrolysis yielded 29.
2-Amino-4-( p-chlorophenyl )-3-cyano-6-( p-hydroxy phenyl)pyridine( 15 ) reacted with active
methylene compounds such as malononitrile and ethyl cyanoacetate to give 30 and 31
, respectively . While cyclocondensation of 15 with phenyl isothiocyanate gave 32. Further,
compound 15 has been cyclized with formamide to give 33.
Hydrolysis of 15 with ethanolic KOH afforded 34 , while its hydrolysis with aqueous KOH gave 35 .On
the other hand, compound 34 underwent cyclocondensation with formamide yielding 36. In addition,
the synthesis of 36 could also be achieved through cyclocondensation of 15 with formic acid.
Treatment of 34 with nitrous acid at 0° C afforded 37 .
34 also, has been cyclized with a mixture of acetic anhydride and acetic acid to give 38.
Furthermore, compound 34 reacted with urea , ethyl chloroformate or diethyl carbonate to give 39 ,
which underwent alkylation with dimethyl sulphate in NaOH yielding 40 , while its alkylation using
methanolic KOH afforded 41 •
Moreover, when compound 35 was treated with acetic anhydride , acetylation and ring closure
occurred to form 4 .2..