[CH3:1][O:2][C:3]([C:5]1([CH3:16])[CH2:9][C:8]2[CH:10]=[C:11]([O:14]C)[CH:12]=[CH:13][C:7]=2[O:6]1)=[O:4].B(Br)(Br)Br>ClCCl>[CH3:1][O:2][C:3]([C:5]1([CH3:16])[CH2:9][C:8]2[CH:10]=[C:11]([OH:14])[CH:12]=[CH:13][C:7]=2[O:6]1)=[O:4]5-methoxy-2-methyl-2,3-dihydro-benzofuran-2-carboxylic acid methyl ester (0.32 g, 1.4 mmol) was dissolved in dichloromethane (10 mL) and cooled to 0° C. A solution of boron tribromide in dichloromethane (1.0 M, 3.5 mL, 3.5 mmol) was added. After 1 hr at 0° C., the reaction was diluted with dichloromethane and washed with brine. The organic phase was dried and concentrated. The residue was dissolved in 7:1 benzene:methanol (10 mL) and treated with TMSCHN2 (1.0 M in hexane) until gas evolution ceased. Removal of the solvent gave a residue which was chromatographed on silica gel eluting with 7:3 hexane:ethyl acetate to give the title compound.
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