Synthetic chemistry of pyrimidines and fused pyrimidines: A review

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

“…[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. The plausible reaction mechanism was illustrated to proceed through the initial nucleophilic attack of the imino nitrogen on the hydrazonoyl halide to provide the amidrazone intermediate via elimination of a hydrogen chloride molecule, followed by the condensation of the amino function with the carbonyl group with the subsequent loss of an ethanol molecule [41] leading to the formation of fused substituted [1,2,4]triazine derivatives. It is worth mentioning that the product 27 can occur in two tautomeric forms, namely, the hydrazone form 27A and the azo tautomeric form 27B, as presented in Figure 4.…”

“…All other chemicals in this study were purchased. 1 An equimolar mixture of compound 11 (0.35 g, 1 mmol), ethyl 2-chloroacetoacetate (0.16 g, 0.14 mL, 1 mmol) and sodium methoxide solution (prepared by dissolving sodium metal [0.023 g, 1 mmol] in methanol [6 mL]) was heated under reflux for 10 hours. The stirring was then kept for 12 hours at room temperature.…”

“…(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. 1 4.2.12 | 9-Methyl-7-phenylpyrido[3′,2′:4,5] thieno[3,2-d]pyrimidine-2,4(1H,3H)dithione (15) Excess carbon disulfide (5 mL) was added to a solution of 3-amino-2-nitrile derivative 1 (2.65 g, 10 mmol) in pyridine (10 mL), and the reaction mixture was heated under reflux for 10 hours. The reaction mixture was diluted with water, and the formed solid was filtered off, washed with water, dried, and crystallized from ethanol to give a buff powder.…”

“…The reaction mixture was concentrated and allowed to cool, and the precipitate formed was filtered off, washed three times by 15 mL of methanol, and dried. 1 6 H 4 -C 3,5 ); 114.22 (C 4 -4-OCH 3 -C 6 H 4 -C 3,5 ); 118.00 (C 8 ); 120.99 (C 2 -4-OCH 3 -C 6 H 4 -C 2,6 ); 121.28 (C 4 -4-OCH 3 -C 6 H 4 -C 2,6 ); 127.46 (C 6 H 5 -C 2,4,6 ); 128.00 (C 9a ); 129.00 (C 6 H 5 -C 3,5 ); 132.00 (C 2 -4-OCH 3 -C 6 H 4 -C 1 ); 133.16 (C 4 -4-OCH 3 -C 6 H 4 -C 1 ); 140.03 (C 6 H 5 -C 1 ); 146.98 (C 9 ); 153.36 (4-OCH 3 -C 6 H 5 -C 4 ); 154.00 (C 5a ); 155. To a stirred solution of compound 15 (3.41 g, 10 mmol) in 1 N aqueous sodium hydroxide (0.8 g, 20 mmol in 20 mL of water) at room temperature, methyl iodide (0.28 g, 0.12 mL, 20 mmol) was added portionwise, and the stirring was continued for 14 hours.…”

“…[1] Thieno[2, 3-b]pyridine derivatives possess diverse pharmacological activities, including cytotoxicity toward different cancer cell lines, [2a-c] antiviral activity, [3] anti-inflammatory activity, [4] and antimicrobial [5] activity, in addition to the treatment of central nervous system (CNS) disorders. [1] Thieno[2, 3-b]pyridine derivatives possess diverse pharmacological activities, including cytotoxicity toward different cancer cell lines, [2a-c] antiviral activity, [3] anti-inflammatory activity, [4] and antimicrobial [5] activity, in addition to the treatment of central nervous system (CNS) disorders.…”