Reaktion #9878

Reaktionsgleichung

HCl

benzylmalonic acid

paraformaldehyde

diethylamine

→

compound 17

Ausbeute 90.0%

2-methylene-3-phenylpropanoic acid

Ausbeute 90.0%

Lösungsmittel

water

ethyl acetate

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigethe reaction temperature below 20° C. (see FIG. 6)
2. 2
   TemperaturThe reaction was then warmed
3. 3
   Temperaturto reflux for 90 min
4. 4
   Temperaturcooled again on ice
5. 5
   Sonstigethe reaction temperature below 10° C
6. 6
   SonstigeThe phases were then separated
7. 7
   WaschenThe organic layer was washed with brine (100 mL)
8. 8
   Trocknendried over sodium sulfate
9. 9
   Filtrationfiltered
10. 10
    Einengenthe filtrate concentrated under vacuum

Vorschrift

A solution of benzylmalonic acid (20.0 g, 0.103 mol, 1 eq) and paraformaldehyde (4.94 g, 0.164 mol, 1.6 eq) in ethyl acetate (150 mL) was cooled (0° C.) and treated with diethylamine (10.65 mL, 0.103 mol, 1 eq) drop wise, keeping the reaction temperature below 20° C. (see FIG. 6). The reaction was then warmed to reflux for 90 min and cooled again on ice. The homogeneous solution was treated with water (20 mL) and concentrated aqueous HCl (12N) (9.0 mL, 0.108 mol) drop wise, keeping the reaction temperature below 10° C. The phases were then separated. The organic layer was washed with brine (100 mL), dried over sodium sulfate, filtered, and the filtrate concentrated under vacuum giving compound 17 as a white solid (15 g, 90%). Rf 0.46 (hexane/EtOAc=7:3). 1H NMR (300 MHz, CDCl3) δ 7.28 (m, 5H), 6.42 (s, 1H), 5.62 (s, 1H), 3.67 (s, 2H). [M−H]− 161.0: tR=2.53 min; purity: 99%.

Quelle