الفهرس 
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Abstract
In the present study there is a brief literature review covering the most important biological activities and the general methods for synthesis of pyrimidine derivatives.
New class of pyrimidine derivatives were obtained starting from ethyl pyrimidine-4-carboxylate 90, which is obtained from reaction of ethyl butanoate with urea. Alkylation of compound 90 with methyl iodide and butyl bromide gave compounds 91a,b. In addition, reaction of compound 90 with hydrazine hydrate yielded the hydrazide 92. This hydrazide was utilized in the synthesis of several hydrazones 93a-g by reaction with different aldehydes. (Scheme1)
Reaction the acid hydrazide 92 with different acid chlorides produced compounds 94a-c. Oxadiazoles 95a-f were obtained from the acid hydrazide 92 by heating under reflux with substituted aromatic acids using phosphorous oxychloride. (Scheme 2)
On the other hand, triazoles 97a-c were unexpectedly obtained from the reaction of acid hydrazide 92 with substituted isothiocyanates instead of the open chained thiosemicarbazides 96a-c. (Scheme 3)
Only p-bromophenyl isothiocyanate reacted with acid hydrazide to give thiosemicarbazide 96d. Compound 96d reacted with NaOH to give triazole-5-thione 99 and reacted with concentrated sulphuric acid to give thiadiazole derivative 100. (Scheme 4)
Other synthetic method was used for the synthesis of pyrimidine derivative 101. The reaction involved the use of 4- benzyloxybenzaldehyde, ethyl cyanoacetate and thiourea. Alkylation of compound 101 with different alkyl halides and substituted phenacyl bromides afforded compounds 102 a-e.Furthermore, chlorination of compound 101 using phosphorous oxychloride produced the chloro compound 103. (Scheme5)
Nucleophilic substitution of the chloro compound 103 with different amino acids produced compounds 104 a-c.
The hydrazino compound 105 was obtained via the reaction of compound 103 with hydrazine hydrate.
Compound 105 was cyclized either to triazolopyrimidine 106 or to tetrazolopyrimidine 107 by the reaction with formic acid or sodium nitrite and hydrochloric acid respectively.3-Methyl-5-substituted pyrazolyl-pyrimidine derivatives 108 a,b were obtained by the reaction of compound 105 with dicarbonyl compounds namely acetyl acetone and benzoyl acetone respectively.
(Scheme 6)
Furthermore, theoretical discussion and detailed survey for the experimental results attained with interpretation of data. The chemical structure of the newly synthesized compounds was confirmed by IR, 1HNMR, 13CNMR, mass spectrometry and elemental analysis.
Some of the newly synthesized pyrimidine derivatives were evaluated for their antimicrobial and anticancer activities.
Considering antimicrobial activity, we observed that most of the targets exhibited broad spectrum activity. However, compounds 90, 92, 93c and 96d represented the highest potency compared to the reference drugs Sulfamethoxazole, Cefotaxime as antimicrobial agents and Nystatin as antifungal agent. On the other hand, compound 93c showed excellent antibacterial activity against gram positive and gram negative bacterial strains and has the highest antifungal activity.