Reaktion #1018246

Reaktionsgleichung

benzyl 2,4-dibromobutyrate

4-fluoropyrazole

sodium hydride

→

benzyl 1-(4-fluoro-1H-pyrazol-1-yl)cyclopropanecarboxylate

Ausbeute 30.5%

Lösungsmittel

ethyl acetate

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONwas added dropwise
2. 2
   Waschenwashed with water and brine
3. 3
   TrocknenThe organics were dried over sodium sulfate
4. 4
   Filtrationfiltered
5. 5
   Einengenconcentrated under reduced pressure
6. 6
   SonstigeThe residue was purified via flash chromatography

Vorschrift

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).

Quelle