Thionyl Chloride → 3-Methoxycinnamoyl Chloride

Participants

Reaction Steps

A solution of 3-methoxycinnamic acid (75.0 g, 0.42 mol) in thionyl chloride (250 mL) was heated at reflux for 1 h. The majority of the the thionyl chloride was then distilled off and the resulting residue was treated with dichloromethane and residual thionyl chloride was removed by codistillation to give 3-methoxycinnamic acid chloride of sufficient purity to be used without further purification. Pyridine (186 mL, 2.3 mol) and N,O-dimethylhydroxylamine hydrochloride (45.17 g, 0.46 mol) were added to a 0° C. solution of 3-methoxycinnamic acid chloride(0.42 mol) in dry dichloromethane (500 mL). The solution was stirred for 18 h at room temperature, diluted with dichloromethane (200 mL), and washed sequentially with 1N HCl, saturated sodium bicarbonate, and brine. It was then dried over MgSO4 and concentrated in vacuo to give the title compound as a dark oil (88.43 g, 95%): 1H NMR (300 MHz, CDCl3) δ3.25 (s, 3H), 3.68 (s, 3H), 3.84 (s, 3H), 6.82-6.86 (m, 1H), 7.00 (d, J=16.1 Hz, 1H), 7.10 (br s, 1H), 7.15-7.20 (m, 1H), 7.32 (t, J=6.6 Hz, 1H), 7.72 (d, J=16.0 Hz, 1H).

Provenance & Evidence