Methanol → 5-(3-Amino-2-hydroxy-phenyl)-thiophene-2-carboxylic acid hydrobromide

Participants

Reaction Steps

5-(3-Amino-2-methoxy-phenyl)-thiophene-2-carboxylic acid 12b (2.2 g, 8.83 mmol) was dissolved in 20 mL of dichloromethane followed by dropwise addition of boron tribromide (35 mL, 35.32 mmol/L). The reaction mixture was reacted at room temperature for 1.5 hours. The reaction was monitored by TLC until the disappearance of the starting materials. Then 5 mL of methanol was added and the mixture was concentrated under reduced pressure. The residue was diluted with 100 mL of ethyl acetate and stirred for 1.5 hours. The mixture was filtered and the filter cake was dried to obtain the title compound 5-(3-amino-2-hydroxy-phenyl)-thiophene-2-carboxylic acid hydrobromide 12c (1.2 g, yield 57.1%) as a grey solid.

Provenance & Evidence