Condensed l,2,4-triazolo

On heating the condensed [l,2,4]-triazolo[4,3- ]pyridazine-6(577)-one-3(27/)-thione 91 with dialkyl acetylenedi-carboxylates in DMF, the subsequent ring transformations yielded the novel tetracyclic 1,3-diazepine cis-92, which can further be converted to 93 in a number of steps involving elimination, decarboxylation, and cyclization oxidation upon heating (Scheme 15) <2001T7191>. 

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... 

Synthesis, set also Heterocyclic synthesis and biological activities of condensed heterocycloln.m-tj, b, or cjquinazolines. 52, I and reactions of l-azirines, 13, 45 of condensed l,2,4-triazolo[3,4-z)heterocycles, 49, 277 by ring-closure of o-substituted t-anilines, 14, 211... 

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