Boron tribromide → 5-Hydroxybenzofuran-2-carboxylic acid
Reaction equation
C[O:2][C:3]1[CH:4]=[CH:5][C:6]2[O:10][C:9]([C:11]([OH:13])=[O:12])=[CH:8][C:7]=2[CH:14]=1.B(Br)(Br)Br.[NH4+].[Cl-]>C(Cl)Cl>[OH:2][C:3]1[CH:4]=[CH:5][C:6]2[O:10][C:9]([C:11]([OH:13])=[O:12])=[CH:8][C:7]=2[CH:14]=1Participants
5
Reactant 3
Product 1
Reagents, catalysts & solvents 1
Procedure
To a cooled (−78° C.) solution of 5-methoxy-benzofuran-2-carboxylic acid (5.0 g, 26.0 mmol) in DCM (100 mL) was added BBr3 (7.4 mL, 19.5 g, 78.0 mmol) and the reaction mixture was stirred (2 h). The reaction mixture was warmed (rt) and subsequently cooled (0° C.) and treated with saturated NH4Cl (100 mL). The resultant biphasic mixture was partitioned and the aqueous layer was extracted with EtOAc (3×100 mL), dried, filtered and concentrated in vacuo to afford the title compound (4.6 g, 100%).