Hydrochloric Acid → 3,4-Dimethoxycinnamic acid

Participants

Reaction Conditions

Reaction Steps

A solution of 3,4-dimethoxybenzaldehyde (5.0 g, 30 mmol) and malonic acid (4.7 g, 45 mmol) in a mixture of piperidine (0.5 mL) and pyridine (15 mL) was heated to 120° C. and stirred overnight. The mixture was cooled to rt and acidified with conc. HCl. The resulting precipitate was filtered and washed with water to give (E)-3-(3,4-dimethoxyphenyl)-2-propenoic acid (5.1 g, 81%) as a pale brown solid; δH (400 MHz, DMSO-d6) 3.78 (s, 3H, OCH3), 3.79 (s, 3H, OCH3), 6.42 (d, J=16.0 Hz, 1H, CH═CHCO2H), 6.96 (d, J5,6=8.0 Hz, 1H, H5), 7.19 (d, J5,6=8.0 Hz, 1H, H6), 7.30 (s, 1H, H2), 7.51 (d, J=16.0 Hz, 1H, CH═CHCO2H).

Provenance & Evidence