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Abstract 1,3-thiazine 3 was obtained from the base induced reaction of thiourea, benzaldehyde and ethyl cyanoacetate. Hydrazonolysis of1,3-thiazine 3 with hydrazine or phenyhydrazine gave pyrimidine ring derivatives 8, 13 respectively. Compound 13 was cyclized with carbon disulphide or formaldehyde to produce triazolopyrimidine 15 and 18, respectively. The synthesis of N-phenylamino pyrimidine derivative 21 was obtained as a result of the reaction of aniline with cyano-1,3-thiazine derivative 3. Compound 21 suffer acid induced ring opening upon treatment with HCl to produce the acid derivative 23. Also oxidative ring opening of cyanopyrimidine 3 was achieved by treating of 21 with H2O2 in the presence of NaOH to produce oxazine 25. Triazolopyrimidine 28 was prepared upon the reaction of thiazine derivative 3 with thiosemicarbazide in basic medium. Compound 28 was transformed to sulphonic acid derivative 29 by the effect of I2 /AcOH. Compound 3 undergo ring transformation upon the effect of NH2OH.HCl to produce pyrimidine derivative 30. Refluxing of amino-1,3-thiazine derivative 3 and ethyl bromoacetate in TEA produce the alkylated pyrimidine product 32. N-alkylation of compound 3 was achieved by reaction of 3 with ethyl iodide to give the alkylated thiazine 33 which in turn undergo ring transformation when subjected to react with hydrazine hydrate to give pyrazole derivative 34. The structure of newly synthesized compounds was elucidated by IR, NMR and elemental analysis. Some of the synthesized compounds are tested for anticancer activities and significant results were found for some compounds. |