3-Methoxycinnamic acid (8) (3.56 g, 19.98 mmol) was dissolved in methanol (100 mL) and 10% Pd/C catalyst (0.44 g) was added. The mixture was stirred in a hydrogen (balloon) atmosphere for 12 h at room temperature. Upon completion of the reaction, the reaction mixture was filtered through diatomaceous earth (Celite) and the diatomaceous earth was washed with ethyl acetate (3 x 30 mL). The filtrates were combined and the ethyl acetate and methanol were removed by evaporation under reduced pressure to give 3-(3-methoxyphenyl)propionic acid (10) (3.59 g, 19.7 mmol, quantitative yield). The product was characterized by 1H NMR (CDCl3, 600 MHz) and 13C NMR (CDCl3, 150 MHz) with the following data: 1H NMR δ 11.93 (1H, s), 7.27 (1H, t, J = 7.5 Hz), 6.88 (2H, m), 6.83 (1H, d, J = 8 Hz), 3.79 (3H, s), 3.79 (3H, s) 2.99 (2H, t, J = 7 Hz), 2.73 (2H, t, J = 7 Hz); 13C NMR δ 179.2, 159.9, 142.0, 129.6, 120.7, 114.2, 111.6, 54.9, 35.5, 30.6.
