Synthesis of Pyrimidines Fused with Azaheterocyclic Five and Six Membered Rings | ||
| Tikrit Journal of Pure Science | ||
| Article 1, Volume 17, Issue 4, December 2012, Pages 103-110 | ||
| Authors | ||
| Shakir M. Saied; ; Rana A. Al-Obaidy; Moayed S. AL. Gawady | ||
| Abstract | ||
| 5-Arylidine barbituric acid derivatives 1(a-h) were prepared from the reaction of this acid with proper aromatic aldehydes in present of acetic acid (also, 5-benzylidine barbituric acid 1a was prepared as an authentic sample from the reaction of benzaldehyde with 1,3-diphenyl-2-propen-1-one in present of pyrimidine).To increase the yields of these derivatives a modified procedure was followed using solvent – free grindstone technique. These arylidines were used as synthons in preparation of the titled compounds by 1,4-Michael addition, thus 2-aryl-5-spirooxiran-1-yl-barbituric acid 2(a-h) were obtained via epoxidation of the proper arylidine by hydrogen peroxide in presence of anhydrous sodium carbonate. The reaction of these oxirans with hydrazine hydrate gave 3-aryl-pyrazolo[3,4-d]pyrimidine-4,6-diones3(a-h).The refluxing of compound(1h) with hydrazine hydrate in presence of pyridine gave 3-(2,6-dichlorophenyl) pyrazolino[3,4-d] pyrimidin- 4,6-dione(4), which on oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) gave the authentic sample of compound(3h). Also, 3-aryl-dihydroisoxazolo[3,4-d]pyrimidine - 4,6-diones 6(a-b and g ) were prepared by the reaction of proper arylidine with hydroxyl amine salt in pyridine and oxidation of the products 3-aryl-3,3a-dihydroisoxazolo [3,4-d] pyrimidine-4,6-diones 5(a-b and g) with (DDQ) . 7- Amino-5-arylpyrimido[4,5-d]pyrimidine-2,4-diones 7(a-b and g) were prepared by the reaction of proper arylidine and guanidine hydrochloride in ethanol. Finally, 5-arylpyrimido[4,5-d] pyrimidine-2,4,7-trione 8(a-c) and 5-arylpyrimido[4,5-d]pyrimidine-2,4-dione -7-thione 9(a) were prepared by the reaction of proper arylidine with urea or thiourea in refluxing ethanol. This procedure was modified to increase the yield using phase-transfer catalytic (PTC) technique using catalytic amount of tetraethylammmonium iodide and aqueous sodium hydroxide solution . The structures of these compounds were confirmed by H1NMR of representative samples in addition to IR ,UV Spectra and authentic samples . | ||
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