Dimethylamine → 2-Methylene-4-phenylbutyric acid

Beteiligte Stoffe

Reaktionsschritte

A mixture of 2-phenylethylmalonic acid (1.8 g), 40% aqueous dimethylamine (1.08 ml, 1 eq) and 37% aqueous formaldehyde (0.64 ml, 1 eq) in water (10 ml) was stirred at room temperature overnight. After cooling at 0° C. the solid was filtered off, washed with water and dried. The white solid was heated at 170° C. for 10 minutes and cooled to room temperature. The resulting gum was dissolved in ethyl acetate (20 ml), washed with 10% potassium hydrogen sulphate solution (10 ml), water (2×10 ml), saturated brine (10 ml), dried (MgSO4) and evaporated to give crude 2-methylene4-phenylbutanoic acid. δH (CDCl3) 2.55-2.90 (4 H, m, 2×CH2), 5.65, 6.85 (2 H, 2×s, ##STR8## 7.25 (5 H, m, Ph). The solid was dissolved in thioacetic acid (1 ml) and heated at 100° C. for 1 hour. After evaporation the gum was dissolved in ethyl acetate (10 ml) and extracted with saturated sodium hydrogen carbonate solution (2×10 ml). The combined extracts were washed with ethyl acetate (2×10 ml) and acidified with 10% potassium hydrogen sulphate solution (pH 3). The aqueous layer was extracted with ethyl acetate (2×10 ml) and the combined extracts washed with water (2×10 ml), dried (MgSO4) and evaporated to yield the title compound as a yellow oil (0.52 g, 24%); δH (CDCl3) 2.00 (2 H, m, CH2), 2.71 (3 H, m, CH2, CH), 3.14 (2 H, m, CH2), 7.24 (5 H, m, Ph). EIMS M+ 252 DCIMS MNH4+ 270.

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