4-Bromo-1-[(2,2-dimethoxyethyl)oxy]-2-methylbenzene → 5-Bromo-7-methylbenzofuran

Participants

Reaction Steps

Polyphosphoric acid (2.0 g) was added to a solution of 4-bromo-1-[(2,2-dimethyloxyethyl)oxy]-2-methylbenzene (6.24 g) in toluene (100 ml) and the resulting mixture was warmed to reflux for 4 hours. The reaction mixture was cooled to room temperature and the supernatant organic layer decanted off. The black residue was basified with 2N aqueous Na2CO3 and extracted with ethyl acetate (100 ml). The organic layers were combined, washed with brine (2×100 ml), dried over MgSO4, ifitered, and the solvent removed under reduced pressure. Purification by MPLC (2% ethyl acetatein-hexane) gave 5-bromo-7-methyl-benzofaran as a colourless oil (2.77 g). 1H NMR (360 MHz,CDCl3)δ2.48 (3H, s), 6.68 (1H, d, J=3.6 Hz), 7.13 (1H, s), 7.53 (1H, s), 7.60 (1H, d, J=3.6 Hz).

Provenance & Evidence