Allyl bromide → 3-(3,5-Dimethoxyphenyl)-1-propene

Participants

Reaction Steps

To a stirred solution of 1.49 g (16.5 mmol) of copper (I) cyanide and 1.39 g (33 mmol) of lithium chloride in 40 mL of THF was added dropwise 15 mL of a 1 M solution of 3,5-dimethoxyphenylmagnesium chloride in THF at −78° C. After stirring for 5 min, 2.5 mL (3.6 g, 30 mmol) of allyl bromide was added dropwise, and the resulting solution was stirred for 16 h while slowly warming to room temperature. The reaction mixture was quenched by slowly adding saturated NH4Cl(aq) and stirring for 5 min. The layers were separated and the aqueous phase was extracted three times with 50-mL portions ethyl acetate. The combined organic fractions were dried (Na2SO4), filtered through a pad of silica gel (eluted with ethyl acetate) and concentrated in vacuo. The residue was chromatographed over silica gel (eluted with 50:1 hexanes-ethyl acetate) to afford 2.59 g of a pale-yellow oil as a 6:1 mixture of 2:3. The mixture was suitable for further reactions without additional purification: 1H NMR (400 MHz, CDCl3) δ 6.36 (d, J=2.4 Hz, 2H), 6.32 (t, J=2.4 Hz, 1H), 6.81-5.87 (m, 1 H), 5.10 (dd, J=16.8, 1.6 Hz, 1 H), 5.07 (dd, J=9.6, 1.6 Hz, 1H), 3.78 (s, 6H), 3.33 (d, J=6.8 Hz, 2H).

Provenance & Evidence