Synthesis of novel fused ring and spiro heterocyclic compounds

The interaction of 4-bromo-3-aryl-isoxazol-5(4H)-ones 1 with 3-alkyl/aryl-4 -amino-5-mercapto-1,2,4-triazoles 3 in ethanol in the presence of pyridine afford 3,8-disubstituted-5H-s-triazolo[3,4-b]isoxazolo[5,4-e]-1,3,4-thiadia zines 4. The synthesis of 3,3'-disubstituted-5'-phenyl-s-triazolo[3,4-b]-1, 3,4-thiadizolidine-spiro[6'.4]isoxazol-5-one 8 is reported by reacting 1 wi th 4-anilino-5-mercapto-3-substituted-1,2,4-triazoles 5. An alternate unamb iguous systhesis of 8 by the interaction of 3-aryl-4,4-dibromo-isoxazol-5-o ne 2 with 5 has been described. The compounds have been characterised by sp ectral data.