Benzyl 2,4-dibromobutanoate

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

Procedure: To a solution of 4-fluoropyrazole (125 mg, 1.45 mmol) in tetrahydrofuran (4 mL) at 0° C. was added sodium hydride (60% suspension in mineral oil, 116 mg, 2.90 mmol). The mixture was stirred at 0° C. for 40 min before benzyl 2,4-dibromobutyrate (0.30 mL, 1.50 mmol) was added dropwise. The reaction mixture was stirred at room temperature for 18 h. The reaction mixture was diluted with ethyl acetate and washed with water and brine. The organics were dried over sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified via flash chromatography to afford benzyl 1-(4-fluoro-1H-pyrazol-1-yl)cyclopropanecarboxylate as a clear oil (115 mg, 30.4%). 1H NMR (400 MHz, CDCl3) δ 1.64-1.70 (m, 2H), 1.81-1.86 (m, 2H), 5.14 (s, 2H), 7.22-7.26 (m, 2H), 7.31-7.36 (m, 3H), 7.40 (td, 2H). was added dropwise washed with water and brine The organics were dried over sodium sulfate filtered concentrated under reduced pressure The residue was purified via flash chromatography

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

Procedure: To a solution of 4-fluoropyrazole (125 mg, 1.45 mmol) in tetrahydrofuran (4 mL) at 0° C. was added sodium hydride (60% suspension in mineral oil, 116 mg, 2.90 mmol). The mixture was stirred at 0° C. for 40 min before benzyl 2,4-dibromobutyrate (0.30 mL, 1.50 mmol) was added dropwise. The reaction mixture was stirred at room temperature for 18 h. The reaction mixture was diluted with ethyl acetate and washed with water and brine. The organics were dried over sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified via flash chromatography to afford benzyl 1-(4-fluoro-1H-pyrazol-1-yl)cyclopropanecarboxylate as a clear oil (115 mg, 30.4%). 1H NMR (400 MHz, CDCl3) δ 1.64-1.70 (m, 2H), 1.81-1.86 (m, 2H), 5.14 (s, 2H), 7.22-7.26 (m, 2H), 7.31-7.36 (m, 3H), 7.40 (td, 2H). was added dropwise washed with water and brine The organics were dried over sodium sulfate filtered concentrated under reduced pressure The residue was purified via flash chromatography

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

Procedure: To a solution of 4-fluoropyrazole (125 mg, 1.45 mmol) in tetrahydrofuran (4 mL) at 0° C. was added sodium hydride (60% suspension in mineral oil, 116 mg, 2.90 mmol). The mixture was stirred at 0° C. for 40 min before benzyl 2,4-dibromobutyrate (0.30 mL, 1.50 mmol) was added dropwise. The reaction mixture was stirred at room temperature for 18 h. The reaction mixture was diluted with ethyl acetate and washed with water and brine. The organics were dried over sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified via flash chromatography to afford benzyl 1-(4-fluoro-1H-pyrazol-1-yl)cyclopropanecarboxylate as a clear oil (115 mg, 30.4%). 1H NMR (400 MHz, CDCl3) δ 1.64-1.70 (m, 2H), 1.81-1.86 (m, 2H), 5.14 (s, 2H), 7.22-7.26 (m, 2H), 7.31-7.36 (m, 3H), 7.40 (td, 2H). was added dropwise washed with water and brine The organics were dried over sodium sulfate filtered concentrated under reduced pressure The residue was purified via flash chromatography