反应详情

温度

65 °C

4.00 g (8.02 mmol) of 4-(3-bromo-phenyl)-3-methyl-2,4-dioxo-butyric acid ethyl ester (synthesized from 3′-bromopropiophenone and diethyl oxalate, following a procedure described in Ksander, Gary M.; McMurry, John E.; Johnson, Mark. A method for the synthesis of unsaturated carbonyl compounds. Journal of Organic Chemistry (1977), 42(7), 1180-5) were dissolved in 12.20 ml of MeOH and 0.37 g (8.02 mmol) of methylhydrazine were added. The reaction was heated under reflux (65° C.) for 1 h. Then the reaction was partitioned between chilled aqueous 1N HCl/EtOAc (3×). The organic phase was washed with aqueous 1N HCl, with aqueous sat. NaCl, dried (Na2SO4) and evaporated. The crude product was purified by flash chromatography (SiO2, n-heptane/EtOAc 99:1) to give 0.61 g of 5-(3-bromo-phenyl)-2,4-dimethyl-2H-pyrazole-3-carboxylic acid ethyl ester as yellow oil (MS: 323.2 MH+, Br) and 1.731 g of 5-(3-bromo-phenyl)-1,4-dimethyl-1H-pyrazole-3-carboxylic acid ethyl ester as yellow oil (MS: 323.2 MH+, Br).

1. temperatureThe reaction was heated
2. customThen the reaction was partitioned
3. temperaturebetween chilled aqueous 1N HCl/EtOAc (3×)
4. washThe organic phase was washed with aqueous 1N HCl, 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)