Synthesis of dipyridazino[3,4-b:4′, 5′-e]pyrazine

Coupling of C-nitro-NH-azoles with arylboronic acids. A route to N-aryl-C-nitroazoles

“…The melting point of the product synthesized by us is 98–99 °C, which is consistent with results obtained by Coburn [18], who oxidized 3-amino-1-phenyl-1 H -pyrazole (Scheme 1, method A), while Chertkov et al determined a value of 127 °C (Scheme 1, method B), which on the other hand fits with the data published by Predvoditeleva [17] (Scheme 1, method D).…”

“…It may be a product of oxidation of 3-amino-1-phenyl-1 H -pyrazole [18], a product of coupling of diaryliodonium salts with 3-nitro-1 H -pyrazole [20], a product of Ullman phenylation of 3-nitro-1 H -pyrazole [34], or a byproduct in the synthesis of 1-phenyl-4-amino-5-methylaminopyridazin-6-one [17] (Scheme 1). …”

“…Very recently, we reviewed the syntheses of N -phenyl- C -nitroazoles [12], and syntheses of their derivatives will be reviewed soon. The range of methods of N -aryl- C -nitroazoles synthesis includes nitration [13], ring closure [14–15], degenerated ANRORC reactions [16], transformation of other cyclic molecules [17], oxidation of aminoazoles [18], and introduction of an aryl substituent at the ring nitrogen atom in starting nitroazole [19–20]. Many of these methods suffer due to the inconvenient conditions of reactions, lack of selectivity, or low yields of the products.…”

(Het)aroylpyruvic acids and their derivatives as promising building blocks for organic synthesis

“…163 The reaction of the acid 4a with 4,5-diamino-1-phenyl-(105a) and 4-amino-5-methylamino-1-phenyl-1,6-dihydropyridazin-6ones (105b) in boiling ethanol has been described. 158 In the case of the diamine 105a, the reaction gives the product of cycloaddition at the a-oxocarboxy group of the acid, 3-benzoylmethyl-6-phenyl-1,2,5,6-tetrahydropyrazino [2,3-d]pyridazine-2,5-dione (106), while the reaction with 105b gives benzoylpyruvic acid N-(5-methylamino-6-oxo-1-phenyl-1,6-dihydropyridazinyl)amide (107). 158 The reaction of the APA 4 with 1,2-diaminobenzimidazole in boiling AcOH occurs chemo-and regioselectively to yield 2-aroylmethyl-3,4-dihydro-1,2,4-triazino[2,3-a]benzimidazol-3-ones 108.…”

Reactions of aroylpyruvic acids withS-methylisothiosemicarbazide hydroiodide and studies of the crystal structures of the reaction products

“…The reactions of heterocyclic 1,2-diamines with aroylpyruvic acids afford fused 1,4-diazine and 1,2,4-triazine systems. [5][6][7][8][9] S-Methylisothiosemicarbazide hydroiodide (1) can be involved in the reaction with p-chlorobenzoylpyruvic acid (2) as a hydrazine, amidine, or 1,2-diamine. Boiling of a mixture of these reagents in EtOH gave a colorless crystalline compound in a yield of 59%.…”