[CH:1](/[C:5]1([CH2:17][CH2:18][C:19](=[O:22])[CH2:20][CH3:21])[CH2:13][C:12]2[C:7](=[CH:8][CH:9]=[C:10]([O:14][CH3:15])[CH:11]=2)[C:6]1=O)=[CH:2]\[CH2:3][CH3:4].[OH-].[Na+]>CO>[CH:1](/[C:5]12[CH2:17][CH2:18][C:19](=[O:22])[C:20]([CH3:21])=[C:6]1[C:7]1[C:12](=[CH:11][C:10]([O:14][CH3:15])=[CH:9][CH:8]=1)[CH2:13]2)=[CH:2]\[CH2:3][CH3:4]A solution of 2-[(1E)-1-butenyl]-5-methoxy-2-(3-oxopentyl)-1-indanone (199 mg, 0.663 mmol) in methanol (5 mL) was treated with 2N aqueous NaOH (1.6 mL) and the resulting mixture was stirred and heated in an oil bath at 85° C. for 7 hours. After cooling to room temperature, the brown solution was partitioned between EtOAc (20 mL) and 0.4N HCl (10 mL). The organic phase was separated, washed with brine (15 ml), dried over MgSO4, filtered, and evaporated under vacuum to a brown oil (208 mg). The crude product was purified by silica gel chromatography on a Biotage FLASH 12S column (1.2×7.5 cm), eluting with 5:1 hexanes:EtOAc, to afford 9a-[(1E)-1-butenyl]-7-methoxy-4-methyl-1,2,9,9a-tetrahydro-3H-fluoren-3-one (67 mg) as an oil.
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