On the Synthesis of New 2-Alkyl/Arylamino-4H-pyrimidino(4,5-e)(1,3,4) thiadiazine-6,8-(5H,7H)diones and 2-Alkyl/Arylimino-3-anilino-2,3- dihydropyrimidino(4,5-d)thiazole-5,7-(4H,6H)-diones.