Condensed 1.2,4-triazines: I. Fused

Condensed 1,2,4-Triazines I. Fused to Heterocycles with Three-, Four-, and Five-Membered Rings... 

Condensed thiophene systems, tetra- and pentacyclic, 32, 127 Condensed 1,2,4-triazines I. Fused to heterocycles with three-, four-, and five-membered rings, 59, 39 Condensed l,2,4-triazolo[3,4-z] heterocycles, synthesis, 49, 277... 

El Ashry, E. S. H., Rashed, N., Taha, M., Ramadan, E., Condensed 1,2,4-Triazines I. Fused to Heterocycles with Three-, Four-, and Five-membered Rings, 59, 39. 

The final chapter is Part II of the survey of condensed 1,2,4-triazines and is authored by E. S. H. El Ashry, N. Rashed, A. Mousaad, and E. Ramadan of Alexandria University, Egypt. The same group wrote Part I in Volume 59, which covered 1,2,4-triazines fused to heterocycles with 3-, 4-, and 5-membered rings. Part II continues the survey to cover 1,2,4-triazines fused to 6- and 7-membered rings and also those fused to two heterocyclic rings. 

Isoxazolo[5,4-, [l,2,4]triazine-4-ones are prepared by six-membered cyclizations of diazonium salts onto adjacent ester or amide substituents on the isoxazole ring (Section 10.13.9.1.2(i)). [l,2,5]Oxadiazolo[3,4- ]pyrazines (Section 10.13.9.1.2(ii)) and [l,2,5]oxadiazolo[3,4- pyridazines (Section 10.13.9.1.2(iii)) are traditionally accessed by reliable six-membered condensation reactions to give the fused pyrazine and pyridazine rings, respectively. 

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