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0 °C

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.

1. washwashed with brine
2. customThe organic phase was dried
3. concentrationconcentrated
4. dissolutionThe residue was dissolved in 7:1 benzene
5. additionmethanol (10 mL) and treated with TMSCHN2 (1.0 M in hexane) until gas evolution
6. customRemoval of the solvent
7. customgave a residue which
8. customwas chromatographed on silica gel eluting with 7:3 hexane