Several 2-arylimino-benzo (4,5-a)-2,3-dihydro-1,3, thiazin-6-one(IV) have been prepared by refluxing 1-aryl-3(1’- benzene carboxylic acid) thio carbamides (III) in ethane for 1.5 hours. These 1-aryl- 3(1’-benzene carboxylic acid)- thio carbamides(III), in turn have been prepared by refluxing different aryl isothio cyanates(II) with anthranilic acid(I) in chloroform medium. The 1,3-thiazines (IV) have been successfully isomerized into their 1,3-pyrimidine analogues (V) using 5% aqueous ethanolic sodium hydroxides solution. The 1, 3-thiazines (IV) are also converted into their benzoyl analogues (VI) by reacting them with benzoyl chloride.