5-Bromo-2-ethylbenzofuran synthesis

Yield:-

Reaction Conditions:

Stage #1: 2-acetyl-5-bromobenzo[b]furanwith potassium hydroxide in ethylene glycol at 150; for 2 h;
Stage #2: in ethylene glycol at 150; for 2 h;

Steps:

32.2 Preparation Example 32-2 5-Bromo-2-ethylbenzo[b]furan

Preparation Example 32-2 5-Bromo-2-ethylbenzo[b]furan 2-Acetyl-5-bromobenzo[b]furan (10.00 g) and hydrazine monohydrate (8.00 g) were stirred in ethylene glycol (60 ml) at 150° C. for 2 hr.. After cooling, potassium hydroxide (9.00 g) was added and the mixture was stirred at 150° C. for 2 hr.. After cooling, toluene (200 ml) and water (100 ml) were added and the separated toluene layer was washed with 10% aqueous solution (100 ml) of ammonium chloride, dried over magnesium sulfate and concentrated to give the objective compound (8.30 g). 1H-NMR(CDCl3, δ ppm): 1.33(3H, t, J=7.5 Hz), 2.79(2H, quartet, J=7.5 Hz), 6.32(1H, s), 7.24-7.31(2H, m), 7.59(1H, d, J=1.8 Hz)

References:

US6348474,2002,B1 Location in patent:Page column 70