Pyridazine Derivatives and Related Compounds, Part 4. Pyrrolo[2,3-c]pyridazines and Furo[2,3-c]pyndazines, Synthesis and Some Reactions

Six‐Membered Heterocycles: 1,2‐, 1,3‐, and 1,4‐Diazines and Related Systems

“…However, since many pyridazines possess potential therapeutic or plant growth inhibitory effects, a wide variety of new syntheses have been developed more recently. 19 As an example (Scheme 19.2), a 1,2-diketone, a cyanoacetate, and hydrazine combine under basic alcoholic conditions to afford 5,6-disubstituted pyridazine-3 (2H)-ones 36 bearing a nitrile group at position 4 [20], a versatile precursor to fused pyridazines [21,22]. Similarly, the reaction of 1-aryl-2-nitroprop-1-enes with an acetoacetate ester and hydrazine offers 3,6-dimethylpyridazines 37 bearing an aryl group at position 5 and a carbohydrazide at position 4 [23,24].…”

Synthesis of Furo[2,3-c]pyridazines via Tandem Transition-Metal Catalysis

“…There are only a handful of reports in the literature describing methods to prepare the furo­[2,3- c ]­pyridazine ring system. In general, these reports rely on one of two approaches: a Dieckmann-type condensation − (Scheme , eq 1) or a Wittig-based strategy , (Scheme , eq 2). While only a few examples of each reaction manifold have been published, these strategies suffer from a tedious starting material preparation and a lack of functional group tolerance.…”

Synthesis of New Thieno- and Pyrazolo- pyridazine Derivatives

“…In continuation of our studies [1][2][3][4][5][6] directed towards synthesis of new pyridazines annelated with various five and six membered heterocycles, we report here the synthesis of thieno-and pyrazolo-pyridazines likely to possess biologically active compounds. The starting material 3-oxo-5,6-di(pyridin-2yl)-2,3-dihydropyridazine-4-carbonitrile 1 has been prepared via the reaction of 2,2'-pyridil monohydrazone with ethyl cyanoacetate in refluxing sodium ethoxide.…”