Novel Synthesis and Characterization of Some Pyrimidine Derivatives of Oxadiazoles, Triazole and 1,3,4-Thiadiazoles

In the present investigation, synthetic methods of 4-aryl-6-methyl-2-oxo-1,2,3,4-tetrahydro pyrimidine-(5)-1,3,4-thiadiazole-2-amine (3) and 4-aryl-6-methyl-2-oxo-1,2,3,4-tetrahydro pyrimidine-(5)-1,3,4-oxadiazole-2-amine (3a) and 4-aryl-6-methyl-2-oxo-1,2,3,4-tetrahydro pyrimidine-(5)-1,3,4-triazole-2-thiol derivative (3b) are described. Compound 1 is converted to carbothiamide 2 by the reaction with ethyl ester followed by thiosemicarbazide. Compound 2 acts as key intermediate for all series of the final compounds. In one pathway, 2 is converted to corresponding thiadiazole 3 by treatment with conc. H2SO4 and NH3 and compound 3a by treatment with I-2 followed by KI and NaOH and compound 3b by treatment with 10 % of NaOH to furnish the final compound. Structural elucidation is accomplished by IR, H-1 NMR and mass spectral data of the synthesized compounds.