Reaktion #59117

Reaktionsgleichung

2-[2-(4-bromophenyl)-2-oxoethyl]-2-propylmalonate

acetone

sodium hydroxide

→

ethyl 2-[2-(4-bromophenyl)-2-oxoethyl]pentanoate

Ausbeute 20.0%

Lösungsmittel

ethanol

Reaktionsbedingungen

Aufarbeitung

1. 1
   EinengenThe clear, orange-red reaction mixture was then concentrated under reduced pressure
2. 2
   workup.DISSOLUTIONthe residue was redissolved in dimethoxyethane (30 mL)
3. 3
   TemperaturThe mixture was heated to 80° C. for 3 h
4. 4
   TemperaturThe reaction mixture was cooled to rt
5. 5
   workup.ADDITIONdiluted with ethyl acetate (100 mL) and water (100 mL)
6. 6
   Extraktionwas extracted into the organic layer
7. 7
   SonstigeThe layers were separated
8. 8
   Extraktionthe aqueous layer extracted with additional ethyl acetate (75 mL)
9. 9
   WaschenThe combined organic layers were washed with saturated aqueous sodium chloride solution (75 mL)
10. 10
    Trocknendried over anhydrous sodium sulfate
11. 11
    Einengenconcentrated under reduced pressure
12. 12
    Sonstigeto afford an orange oil
13. 13
    SonstigeThe crude product was purified by flash chromatography (10:1 hexane:ethyl acetate)

Vorschrift

To a 200 mL flask was added crude 2-[2-(4-bromophenyl)-2-oxoethyl]-2-propylmalonate (7.62 g, 19.2 mmol), acetone (21 mL), and ethanol (19 mL), followed by addition of 1 N aqueous sodium hydroxide solution (19.1 mL). The reaction mixture was heated to 55° C. for 3 h. The clear, orange-red reaction mixture was then concentrated under reduced pressure and the residue was redissolved in dimethoxyethane (30 mL). The mixture was heated to 80° C. for 3 h. The reaction mixture was cooled to rt, diluted with ethyl acetate (100 mL) and water (100 mL), and stirred for 15 minutes until almost all color was extracted into the organic layer. The layers were separated and the aqueous layer extracted with additional ethyl acetate (75 mL). The combined organic layers were washed with saturated aqueous sodium chloride solution (75 mL), dried over anhydrous sodium sulfate, and concentrated under reduced pressure to afford an orange oil. The crude product was purified by flash chromatography (10:1 hexane:ethyl acetate) to afford ethyl 2-[2-(4-bromophenyl)-2-oxoethyl]pentanoate (1.33 g, 20%). LC-MS ret. time 3.60 min, m/z 326.05 (MH+); 1H NMR (300 MHz, CDCl3) δ 0.87 (t, 3H), 1.25 (t, 3H), 1.29-1.43 (m, 2H), 1.57-1.73 (m, 2H), 2.90-3.08 (m, 2H), 3.34-3.47 (m, 2H), 4.15 (q, 2H), 7.59 (d, 4H), 7.82 (d, 2H).

Quelle