4,4-二氟-3-氧代丁酸甲酯

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To a solution of methyl 4,4-difluoro-3-oxobutanoate (64 g, 0.38 mol) in methanol (500 mL) was added methylhydrazine (20.5 mL, 0.38 mol). The reaction mixture was left to stir overnight at room temperature. The volatiles were removed in vacuo, toluene was added (400 mL), the mixture was evaporated again, and this procedure was repeated. The resulting solid residue was purified chromatographically on silica gel using ethyl acetate/dichloromethane mixture (1:2, Rf=0.35). The resulting oil was crystallized from ether (200 mL) and dried under the vacuum of a membrane pump (10 mm Hg) for 3 h to give 28 g (49.8%) of the title product. The reaction mixture was left The volatiles were removed in vacuo, toluene was added (400 mL) the mixture was evaporated again The resulting solid residue was purified chromatographically on silica gel The resulting oil was crystallized from ether (200 mL) dried under the vacuum of a membrane pump (10 mm Hg) for 3 h

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To a solution of methyl 4,4-difluoro-3-oxobutanoate (64 g, 0.38 mol) in methanol (500 mL) was added methylhydrazine (20.5 mL, 0.38 mol). The reaction mixture was left to stir overnight at room temperature. The volatiles were removed in vacuo, toluene was added (400 mL), the mixture was evaporated again, and this procedure was repeated. The resulting solid residue was purified chromatographically on silica gel using ethyl acetate/dichloromethane mixture (1:2, Rf=0.35). The resulting oil was crystallized from ether (200 mL) and dried under the vacuum of a membrane pump (10 mm Hg) for 3 h to give 28 g (49.8%) of the title product. The reaction mixture was left The volatiles were removed in vacuo, toluene was added (400 mL) the mixture was evaporated again The resulting solid residue was purified chromatographically on silica gel The resulting oil was crystallized from ether (200 mL) dried under the vacuum of a membrane pump (10 mm Hg) for 3 h

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: The procedure of Example 4 was repeated using methanol instead of ethanol. After distillation the methyl ester was obtained as a colorless liquid. According to the 1H NMR data the product was a tautomeric mixture of ca. 60% keto form and ca. 40% enol form (methyl 4,4-difluoro-3-hydroxybut-2-enoate). After distillation the methyl ester was obtained as a colorless liquid