With the rapid development and complex challenges of chemical substances, new drug synthesis pathways are usually the most effective.36725-28-7,6-(4-Aminophenyl)-5-methyl-4,5-dihydropyridazin-3(2H)-one,as a common compound, the synthetic route is as follows.
Example 1 (Intermediate Compound) (R)-6-(4-hydrazino-phenyl)-5-methyl-4,5-dihydro-2H-pyridazin-3-one A slight modification on the procedure described in J.Med.Chem. (1990), 33(10), 2870-2875 was used as follows. A solution of sodium nitrite (1.7 g) in water (12.5 ml) was added slowly at 0-5 C. to a solution of (R)-6-(4-aminophenyl)-5-methyl-4,5-dihydro-2H-pyridazin-3-one (5 g) in 1 M hydrochloric acid (75 ml). The resulting solution was stirred on ice bath for five minutes and then added slowly to a solution of tin(II)chloride dihydrate (17 g) in 1 M hydrochloric acid (150 ml) keeping the reaction temperature below 5 C. This solution was stirred on ice for forty minutes and then a solution of 50% NaOH (75 ml) was quickly added. The resulting mixture was stirred on ice bath until the temperature reached zero degrees Celsius. The crystals were filtered and washed with dilute ammonia. Yield: 5.0 g, 93%. HPLC: enantiomerically pure. 1H NMR (400 MHz, DMSO-d6): delta=1.04 (d, 3H, CH3), 2.17 (d, 1H, J=16 Hz), 2.60 (m, 1H), 3.29 (m, 1H), 4.04 (s, 2H, NH2), 6.77 (d, 2H, J=8 Hz), 7.09 (b, 1H, NH), 7.54 (d, 2H, J=8 Hz), 10.66 (s, 1H, NHCO)., 36725-28-7
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Reference：
Patent; Pystynen, Jarmo; Pippuri, Aino; Luiro, Anne; Nore, Pentii; Backstrom, Reijo; Lonnberg, Kari; Haikala, Heimo; Levijoki, Jouko; Kaheinen, Petri; Kaivola, Juha; US2003/158200; (2003); A1;,
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