反应详情

温度

65 °C

3.00 g (10.52 mmol) of 4-(3-bromo-phenyl)-2,4-dioxo-butyric acid methyl ester were suspended in 16 ml of EtOH and 0.485 g (10.52 mmol) of methylhydrazine were added. The reaction was heated under reflux (65° C.) for 5 h. Then the solvent was evaporated and the residue was partitioned between aqueous 1N HCl/EtOAc (3×). The organic phases were washed with aqueous sat. NaCl, dried (Na2SO4) and evaporated. The crude product was purified by flash chromatography (SiO2, n-heptane/EtOAc 99:1) to give 1.64 g (37%) of 5-(3-bromo-phenyl)-2-methyl-2H-pyrazole-3-carboxylic acid methyl ester (and ethyl ester) as white powder (MS: methyl ester 295.1 MH+, 1 Br; ethyl ester 309.1 MH+, 1 Br) and 1.11 g (28%) of 5-(3-bromo-phenyl)-1-methyl-1H-pyrazole-3-carboxylic acid methyl ester (and ethyl ester) as yellow oil (MS: methyl ester 295.1 MH+, 1 Br; ethyl ester 309.1 MH+, 1 Br).

1. temperatureThe reaction was heated
2. customThen the solvent was evaporated
3. customthe residue was partitioned between aqueous 1N HCl/EtOAc (3×)
4. washThe organic phases were washed with aqueous sat. NaCl
5. dry with materialdried (Na2SO4)
6. customevaporated
7. customThe crude product was purified by flash chromatography (SiO2, n-heptane/EtOAc 99:1)