Utility of thieno[2,3-b] pyridine derivatives in the synthesis of some condensed heterocyclic compounds with expected biological activity

Synthesis and antitumor evaluation of some new derivatives and fused heterocyclic compounds derived from thieno[2,3‐b]pyridine: Part 2

“…Synthesis of pyrimido [3,4-b][1,2,4]triazin-3(4H)-one derivative 27 was achieved by the reaction of 3-amino-4iminopyrimidine derivative [19] 26 with ethyl 2-chloro-2-[2-(4-chlorophenyl)hydrazono]acetate (16b) [30] in refluxing absolute ethanol containing a catalytic drops of triethylamine. [41] The 1 H NMR spectrum of compound 27 displayed four deuterium oxide exchangeable singlet signals at δ 10.69, δ 11.57, and δ 12.98 ppm corresponding to triazine-NH, hydrazone-NH, and tautomeric OH protons, respectively.…”

“…[19] However, reagents (16a), [29] (16b), [30] and (20) [37] were prepared according to the reported methods. (9) An ice-cold solution of compound 8 [19] (0.62 g, 2 mmol) in a mixture of concentrated sulfuric acid (3 mL) and glacial acetic acid (15 mL) was treated with sodium nitrite solution (0.42 g, 6 mmol in 10 mL of H 2 O) portionwise over a period 30 minutes while stirring at 0-5°C. (9) An ice-cold solution of compound 8 [19] (0.62 g, 2 mmol) in a mixture of concentrated sulfuric acid (3 mL) and glacial acetic acid (15 mL) was treated with sodium nitrite solution (0.42 g, 6 mmol in 10 mL of H 2 O) portionwise over a period 30 minutes while stirring at 0-5°C.…”

“…The crude product was purified by crystallization from ethanol. 45 (24) To a solution of compound 23 [19] (1.61 g, 5 mmol) in absolute ethanol (20 mL), a solution of benzohydrazide 20 [37] (0.68 g, 5 mmol) in absolute ethanol (10 mL) was added and stirred at room temperature for 3 hours. The reaction mixture was poured onto ice-cold water, and the separated solid was filtered, washed with water, dried, and crystallized from EtOH/DMF mixture (3:1) to afford chocolate brown crystals.…”

“…The reaction mixture was poured onto ice-cold water, and the separated solid was filtered, washed with water, dried, and crystallized from EtOH/DMF mixture (3:1) to afford chocolate brown crystals. (27) An equimolar mixture of compound 26 [19] (1.54 g, 5 mmol), ethyl 2-chloro-2-[2-(4-chlorophenyl)hydrazono] acetate (16b) [30] (1.31 g, 5 mmol), and triethylamine (0.51 g, 0.70 mL, 5 mmol) was heated under reflux in absolute ethanol (40 mL) for 13 hours. 1 A mixture of compound 18 (0.74 g, 2 mmol) and an equimolar amount of benzohydrazide (20) [37] (0.27 g, 2 mmol) was heated under reflux in pyridine (10 mL) for 24 hours.…”

Synthesis and Anticancer Activity Study of Some Novel Substituted and Fused Pyridotriazepine Derivatives

“…Cyanothioacetamide was reported to be utilized in various reactions involving the synthesis of different 4‐amino‐2‐thioxopyridine‐3‐carbonitrile derivatives ; therefore, compound 11 was prepared by refluxing equivalent amounts of compound 2 and cyanothioacetamide in dimethylformamide containing catalytic amount of triethylamine. 1 H NMR spectrum of compound 11 showed deuterium oxide exchangeable singlet signals at δ 7.06 and 8.12 ppm attributed to pyridine–NH and SH–tautomeric protons, respectively.…”