الفهرس 
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Abstract
A new series of pyrido[2,3-d]pyrimidine derivatives were synthesized from hydrazinyl pyrido[2,3-d] pyrimidine derivative (8). Firstly , Cyclocondensation of the hydrazinyl derivative 8 with bielectrophilic species such as ethyl acetoacetate, ethyl cayanoacetate, acetylacetone and chloro acetylacetone afforded the pyrazole derivatives (9-12) respectively by fusion an equimolar amount with few drops of acetic acid (Scheme 1)
(Scheme 1)
Cyclization of compound 8 with phenyl isothiocyanate, potassium isothiocyanate and carbone disulphide afforded the triazolopyrimidine derivatives 13-15 through the elimination of H2S molecule in case of 13, 15 and H2O in formation of 14 (Scheme 2).
The reaction of hydrazinopyrido[2,3-d]pyrimidine 8 with acetic acid, formic, and trifloroacetic acid in the presence of drops of HCl afforded the products 16-18 (Scheme 3).
(Scheme 3)
On the other hand, when hydrazinopyrido[2,3-d]pyrimidine 8 was submitted to react with bromoacetophenone scheme 4. It yielded the pyrimidine derivative 19A rather than the expected product 19B. This is because the carbonyl group in bromoacetophenone formed schiff base with the amino group followed by elimination of HBr gas. So, reaction precedes via nucleophilic substitution reaction in the interimedate cyclized in basic medium afforded pyrimidine derivative proceeds 19A.
(Scheme 4)
Moreover, the nucleophilicity of NH2 in precursor 8 was investigated towards the formation of triazole derivatives by reaction of compound 8 with different carbonyl compounds in as shown scheme (5). So, reactions of hydrazinopyrimidine 8 with different aldehyde compounds namely, 5-Methyl furfural, 2-Thiophene carboxaldehyde, and 4-Formyl-antipyrine, give compounds 20-22 respectively. Compounds 20-22 were formed through condensation followed by cyclization afforded triazole derivatives.
(Scheme 5)
A green synthesis of pyridopyrimidine derivatives 25 A,B was prepared
(Scheme 6)
Reaction of compound 25 with one mole methyl iodide , Chloroacetic acid and ethyl chloroacetate by stiring at room tempreture to give the S-alkylated products 26 and 30a, 30b respectively. N,N dialkylated derivatves 29a, b and 31a,b were obtained also by using two equivalent moles of different alkyl halides by refluxing.
(Scheme 7)
The reaction of 25A,B with hydrazine hydrate under different conditions to yielded 2-hydrazino derivatives 32 A,B and 33B
(Scheme 8)
Treatment of 32B with two moles of benzoyl isothiocyante , ,diethyl oxalate, pyruvic acid ,2,4-pentanedione, and ethyl bromoacetoacetate afforded the corresponding triazolopyridopyrimidine benzamide 34 triazine pyridopyrimido 37, oxadiazine pyridopyrimidotriazine 38 ,pyrazolo pyridopyrimidotriazine 39 , oxoethylhydrazinyl-pyrido[2,3-d]pyrimidine 40 while one mole of parahydroxy benzaldyde and glucose with the hydrazine 32B gave pyridopyrimidinecarbohydrazide derivatives 35 and 41.
(Scheme 9)