Study with thienopyridazines: synthesis of new thieno [3,4-d] pyridazines and exploration of their reactivity toward electron poor olefins

It has been found that III, prepared via condensing II with ethyl cyanoacetate in presence of ammonium acetate, give the thienopyridazine thioamide VIII on treatment with sulfur in ethanolic triethylamine. The mechanism of formation of this product is discussed. Compound VIII reacts with maleic anhydride to yield the phthalazine X

Nitriles in organic synthesis: synthesis of some new Polyfunctionally substituted pyrazines and pyrazine derivatives

It has been found that alpha-tosyloximinomalononitrile [Ib] reacted with benzoylacetonitrile to yield the pyridinium salt II. Compound II reacted with hydrazine hydrate and hydroxylamine hydrochloride to give VII and VIII, respectively. On the other hand, compound II undergoes cyclization by boiling in acetic acid/hydrochloric acid mixture to give VI. When Ib reacted with cyanoacetamide and pyridine it yielded the pyridinium salt III which on reacting with hydrazine hydrate, hydroxylamine hydrochloride and thiourea yielded X, XI and XII, respectively. III also undergoes cyclization by boiling in acetic acid/hydrochloric acid mixture to yield the pyrazine derivative V. Compound Ib reacted with cyanoacetamide by boiling in pyridine to give IV