Abstract: Methylation of 4-amino-6-methyl-3,5-dithio[1,2,4]-triazine (1) gave its -3-methylthio-analogue (2) which on treatment with hydrazine hydrate afforded the corresponding hydrazino derivative 3  Reacting 3 with triethyl orthformate furnished 4. Refluxing 3 with phenyl isothiocyanate afforded 5, which could be cyclized on boiling in Py/DMF to furnish 6. Treatment of 5 with malonic acid in acetyl chloride gave 7. Heating 3 with 1,3-dioxo-1,3-dihydro-isoindol-2-yl alkyl acetic acid derivatives in POCl3 furnished 11a,b.  Hydrolysis of 11a,b with HCl afforded 12a,b. Warming 3 with some 4-toluenesulphonylamino (acetic and/or propionic) acid gave 14a,b. Hydrolysis of 14a gave 12a. Refluxing 3 with 6,8-dibromo-3,1-benzoxazin-4H-one afforded 16a-c. 18 could be obtained by condensation of 3 with benzylidene-1,3-oxazolin-5-one. Refluxing 3 with benzaldehyde and trialkyl phosphites gave 20a,b. 23a,b were obtained by reacting 3 with some aromatic aldehydes.

Keywords: 1,2,4-Triazines, isothiocyanate, 3,1-benzoxazin-4H-ones,  antimicrobial.