[CH3:1][O:2][C:3]1[CH:11]=[CH:10][C:9]([O:12][CH3:13])=[C:8]2[C:4]=1[CH2:5][CH2:6][C:7]2=O.Cl(O)(=O)(=O)=O.[H][H].C([O-])(=O)C.[K+]>[Pd].C(O)(=O)C>[CH3:13][O:12][C:9]1[CH:10]=[CH:11][C:3]([O:2][CH3:1])=[C:4]2[C:8]=1[CH2:7][CH2:6][CH2:5]2
A mixture of intermediate A (19 g, 99 mmole), perchloric acid (2.5 ml of a 70% aqueous solution) and 10% palladium on carbon catalyst (2 g) in acetic acid (250 ml) was placed in a Paar bottle and shaken under 40 psi (2.75 bars) of hydrogen in a Paar shaker apparatus for 15 hours. Solid potassium acetate was added, and the mixture was filtered through a Celite pad. The Celite pad was washed with tetrahydrofuran, and the combined filtrates were poured into ice water (2 liters). The resulting white solid was isolated by filtration, washed with water, and dried under vacuum. Chromatography (silica, dichloromethane) afforded the desired product, 4,7-dimethoxyindane (intermediate B) as a white solid (8.5 g). White needles were obtained from ethanol:water (1:1), mp 82°-84°.
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