Acetic Anhydride → Tert-butyl 5-amino-1-(4-methoxycarbonylphenyl)pyrazole-4-carboxylate

Participants

Reaction Conditions

Reaction Steps

t-Butyl cyanoacetate (14.1 g, 100 mmol) was dissolved in triethyl orthoformate (24.8 mL, 150 mmol). Acetic anhydride (9.625 mL, 100 mL) was added and the mixture heated to 125° C. for 3 h and then volatiles were removed by evaporation under reduced pressure. The residue was dissolved in ethanol (100 mL) and methyl 4-hydrazinylbenzoate hydrochloride (Intermediate #123) (6.06 g, 30 mmol) and DIPEA (5.23 mL, 30 mmol) was added. The mixture was heated to reflux for 5 h and then evaporated under reduced pressure to leave a brown oil which was dissolved in ethyl acetate (300 mL) and washed with water (2×100 mL) and brine (100 mL), dried (MgSO4) and evaporated. The residue was purified by chromatography on silica gel (120 g silica, EtOAc/Hexane 0-50%) to give the title compound as a yellow solid. (7.1 g)

Provenance & Evidence