[CH:1]([C:3]([CH3:5])=[O:4])=[CH2:2].N12CCCN=C1CCCCC2.[CH2:17]([CH:21]1[CH2:29][C:28]2[C:23](=[CH:24][CH:25]=[C:26]([O:31][CH3:32])[C:27]=2[CH3:30])[C:22]1=[O:33])[CH2:18][CH2:19][CH3:20]>O1CCCC1.CCOCC>[CH2:17]([C:21]1([CH2:2][CH2:1][C:3](=[O:4])[CH3:5])[CH2:29][C:28]2[C:23](=[CH:24][CH:25]=[C:26]([O:31][CH3:32])[C:27]=2[CH3:30])[C:22]1=[O:33])[CH2:18][CH2:19][CH3:20]
Methyl vinyl ketone (MVK, 0.49 mL, 5.9 mmol) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, 0.12 mL, 0.8 mmol) were added to a solution of impure 2-butyl-5-methoxy-4-methyl-1-indanone (0.90 g, 3.9 mmol) in anhydrous tetrahydrofuran (THF, 3.9 mL). The resulting solution was stirred at room temperature for 30 hours, then diluted with Et2O (50 mL), washed with water (20 mL), 1N HCl (20 mL), and brine (20 mL), dried over MgSO4, filtered, and evaporated under vacuum to an amber oil (1.23 g). The crude product was purified by chromatography on EM silica gel 60 (230-400 mesh, 125 mL dry, packed under 4:1 hexanes-EtOAc). The column was eluted with 4:1 hexanes-EtOAc, collecting 25 mL fractions. Fractions 14-27 gave a 93:2:5 mixture (0.96 g) of 2-butyl-5-methoxy-4-methyl-2-(3-oxo-butyl)-1-indanone, the 6-methyl isomer, and the desmethyl product. This material was used in the next step.
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