Synthesis
The general procedure for the synthesis of 5-bromo-6-phenylpyridazin-3(2H)-one from 3,4-dibromo-5-phenylfuran-2(5H)-one was as follows: to a solution of 3,4-dibromo-5-phenylfuran-2(5H)-one (600 mg, 1.887 mmol) in ethanol (5 mL) at 0 °C, hydrazine hydrate (0.102 mL, 2.076 mmol). The reaction mixture was stirred at room temperature for 10 min, followed by heating to reflux and kept for 2 h. The reaction was carried out on a cooled surface with the addition of hydrazine hydrate (1.076 mmol). Upon completion of the reaction, the mixture was cooled to room temperature, at which time a precipitate was generated. The precipitate was collected by filtration and washed with cold ethanol to give the final 5-bromo-6-phenylpyridazin-3(2H)-one (458 mg, 99% yield) as a light orange solid.LCMS analysis showed m/z = 251 [M + H]+ .
References
[1] Bioorganic and Medicinal Chemistry Letters, 2015, vol. 25, # 5, p. 1030 - 1035
[2] Journal of Heterocyclic Chemistry, 1998, vol. 35, # 6, p. 1421 - 1428
[3] Bioorganic and Medicinal Chemistry, 2002, vol. 10, # 9, p. 2873 - 2882
[4] Patent: WO2010/77275, 2010, A1. Location in patent: Page/Page column 95
