Boron tribromide → 6-Hydroxy-2-methylbenzo[b]thiophene-3-carboxylic acid

Participants

Reaction Steps

To a solution of 6-methoxy-2-methyl-1-benzothiophene-3-carboxylic acid 48-A (5 g, 22.5 mmol) in CH2Cl2 (50 ml) was added BBr3 (33 ml, 1M CH2Cl2 solution) at −78° C. After being stirred for 1 hour the cooling bath was removed. The reaction was stirred at room temperature overnight. The reaction was quenched with water at 0° C. The mixture was extracted with EtOAc. Insoluble was collected by filtration to yield 2.1 g of 6-hydroxy-2-methyl-1-benzothiophene-3-carboxylic acid (B). The organic layer was washed with brine, dried (MgSO4) and concentrated to give 2.7 g of 48-B.

Provenance & Evidence