[CH3:1][C:2]1([CH3:16])[CH2:6][C:5]2[C:7]([CH3:15])=[C:8]([CH3:14])[C:9]([CH:12]=O)=[C:10]([CH3:11])[C:4]=2[O:3]1.O.[OH-].[Na+].[CH3:20][C:21]([CH3:23])=[O:22]>>[CH3:1][C:2]1([CH3:16])[CH2:6][C:5]2[C:7]([CH3:15])=[C:8]([CH3:14])[C:9]([CH:12]=[CH:20][C:21](=[O:22])[CH3:23])=[C:10]([CH3:11])[C:4]=2[O:3]1To a solution of 37 g of the 2,3-dihydro-2,2,4,5,7-pentamethylbenzofuran-6-carboxaldehyde in 125 ml of acetone was added 60 ml of water and 68 g of 2% aqueous solution of sodium hydroxide. After refluxing for 20 hours, the reaction mixture was quenched with 10 ml of 2N aqueous solution of hydrochloric acid and the aqueous layer was extracted with dichloromethane. The combined organic extracts were dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to afford a crude product. Final purification was carried by recrystallization to afford 42.4 g of 4-(2,3-dihydro-2,2,4,5,7-pentamethylbenzofuran-6-yl)-3-butene-2-one.
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