P(Cl)(Cl)(Cl)=O.CN(C)[CH:8]=[O:9].[CH3:11][C:12]1[CH:16]=[C:15]([C:17]2[CH:22]=[CH:21][C:20]([CH3:23])=[CH:19][CH:18]=2)[O:14][CH:13]=1.[OH-].[Na+]>ClC(Cl)C>[CH:8]([C:13]1[O:14][C:15]([C:17]2[CH:22]=[CH:21][C:20]([CH3:23])=[CH:19][CH:18]=2)=[CH:16][C:12]=1[CH3:11])=[O:9]Phosphorus oxychloride (12 ml) was added slowly to dimethylformamide (9.85 ml) with stirring at 0° C., and the mixture stirred at 0° C. for 30 minutes. A solution of 3-methyl-5-(4-methylphenyl)furan (22 g) in 50 ml of dichloroethane was added dropwise over a period of 15 minutes, maintaining the temperature at 0° C. The mixture was then stirred at room temperature for 11/2 hours. Ice water was then added, and the pH of the aqueous layer adjusted to about 8 with dilute sodium hydroxide. The organic layer was separated, the aqueous layer extracted with dichloromethane, the organic portions combined and solvent removed under reduced pressure. The solvent was removed from the filtrate under reduced pressure, and the residue flash chromatographed on silica gel, eluting with 10% ethyl acetate in heptane, to yield 19.2 g of 2-formyl-3-methyl-5-(4-methylphenyl)furan.
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