Reaktion #1018244

Reaktionsgleichung

sodium hydride

4-methylpyrazole

tert-butyl 2,4-dibromobutanoate

→

tert-butyl 1-(4-methyl-1H-pyrazol-1-yl)cyclopropanecarboxylate

Ausbeute 44.6%

Lösungsmittel

tetrahydrofuran

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONwas added
2. 2
   workup.ADDITIONwas added dropwise at 0° C
3. 3
   workup.WAITat room temperature for 18 h
4. 4
   SonstigeThe solvent was removed under reduced pressure and water and ethyl acetate
5. 5
   workup.ADDITIONwere added to the residue
6. 6
   SonstigeThe layers were separated
7. 7
   Extraktionthe aqueous layer was extracted with ethyl acetate (3×)
8. 8
   TrocknenThe combined organics were dried over magnesium sulfate
9. 9
   Filtrationfiltered
10. 10
    Einengenconcentrated under reduced pressure
11. 11
    SonstigeThe crude material was purified via flash chromatography (0-50% ethyl acetate in heptanes)

Vorschrift

Into a 25 mL round bottom flask were added sodium hydride (60% dispersion in mineral oil, 164.3 mg, 4.1 mmol) and anhydrous tetrahydrofuran (8 mL). The mixture was cooled with an ice-water bath before a solution of 4-methylpyrazole (204.2 mg, 2.487 mmol) in anhydrous tetrahydrofuran (2 mL) was added. The mixture was stirred in the ice-water bath for 30 minutes before tert-butyl 2,4-dibromobutanoate (0.48 mL, 2.2 mmol) was added dropwise at 0° C. The reaction mixture was stirred at 0° C. for 30 minutes and then at room temperature for 18 h. The solvent was removed under reduced pressure and water and ethyl acetate were added to the residue. The layers were separated and the aqueous layer was extracted with ethyl acetate (3×). The combined organics were dried over magnesium sulfate, filtered and concentrated under reduced pressure. The crude material was purified via flash chromatography (0-50% ethyl acetate in heptanes) to afford tert-butyl 1-(4-methyl-1H-pyrazol-1-yl)cyclopropanecarboxylate (218 mg, 44%). 1H NMR (400 MHz, CDCl3) δ 1.33 (s, 9H), 1.45-1.51 (m, 2H), 1.61-1.67 (m, 2H)H), 1.98-2.01 (m, 3H)H), 7.21 (s, 1H), 7.23-7.26 (m, 1H).

Quelle