Phosphoric Acid → Ethyl 5-bromo-6-methoxybenzo[b]thiophene-3-carboxylate

Participants

Reaction Steps

Ethyl 3-(3-methoxy-4-bromophenylthio)-2-oxopropanoate (D3) (3.7 g, 11 mmoles) in chlorobenzene (25 ml) was treated with phosphorus pentoxide (11.1 g, 78 mmoles) and 85% phosphoric acid (5.5 ml). The mixture was heated under reflux for 6 hrs. The mixture was allowed to cool and then partitioned between water (150 ml) and dichloromethane. The organics were washed several times with water then dried (Na2SO4). Evaporation to dryness followed by flash chromatography on TLC silica gel eluting with dichloromethane/60-80 petrol-ether 1:1 gave the title compound (D4) (0.94 g, 27%).

Provenance & Evidence