Acetic Anhydride → Methyl 1-acetyl-1H-thieno[3,2-c]pyrazole-5-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a solution of methyl 4-amino-5-methylthiophene-2-carboxylate (F-4) (5.1 g, 30 mmol) in toluene (120 mL) were added acetic anhydride (16.0 g, 0.12 mol) and potassium acetate (1.5 g, 15.1 mmol). The reaction mixture was stirred at 100° C. for 3 h. After cooled to room temperature, the reaction mixture was treated with isobutyl nitrite (10.5 g, 90.0 mmol), and then stirred at 100° C. overnight. Water was added, and then the mixture was extracted with ethyl acetate. The combined organic layers were washed with brine, dried over Na2SO4 and concentrated. The residue was purified by chromatography eluting with Pet/EtOAc=10/1 to afford the title compound (5.3 g) as the product.

Provenance & Evidence