methyl 4-(2-bromophenyl)-2,4-dioxobutanoate

Conditions: temp:130.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of methyl 4-(2-bromophenyl)-2,4-dioxobutanoate (540 mg, 0.0019 mol) in AcOH (4 mL) was added hydrazine monohydrate (67 mg, 0.00208 mol). The reaction mixture was allowed to stir at 130° C. overnight and then concentrated. The residue was dissolved in EtOAc, washed with aq. NaHCO3 and brine, dried over Na2SO4, filtered and concentrated to give methyl 3-(2-bromophenyl)-1H-pyrazole-5-carboxylate (0.516 g, 97%) as a white solid. LCMS: (FA) ES+ 283.2, ES-281.2. concentrated The residue was dissolved in EtOAc washed with aq. NaHCO3 and brine dried over Na2SO4 filtered concentrated

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Sodium (120 mg, 0.0051 mol) was added slowly to MeOH (2.5 mL, 0.062 mol) at −5° C. To this solution were added dimethyl oxalate (500 mg, 0.0042 mol) and 1-(2-bromophenyl)ethanone (840 mg, 0.0042 mol) in Et2O (5 mL). The reaction mixture was allowed to stir for 12 h and then concentrated and partitioned between Et2O and water. The aqueous solution was separated and cooled in an ice bath. AcOH was added followed by 1N HCl until the solution was acidic. The mixture was extracted with Et2O, and organic solution was dried over Na2SO4, filtered and concentrated to afford methyl 4-(2-bromophenyl)-2,4-dioxobutanoate (1.08 g, 89%) which was used without purification in the next step. LCMS: (FA) ES+ 287.0 concentrated partitioned between Et2O and water The aqueous solution was separated cooled in an ice bath AcOH was added The mixture was extracted with Et2O, and organic solution was dried over Na2SO4 filtered concentrated