[CH2:1]([O:3][C:4]([C:6]1[O:7][C:8]2[CH:15]=[CH:14][C:13]([Cl:16])=[C:12]([OH:17])[C:9]=2[C:10]=1[CH3:11])=[O:5])[CH3:2].[CH:18](Br)([CH3:20])[CH3:19].C([O-])([O-])=O.[K+].[K+]>CN(C=O)C>[CH2:1]([O:3][C:4]([C:6]1[O:7][C:8]2[CH:15]=[CH:14][C:13]([Cl:16])=[C:12]([O:17][CH:18]([CH3:20])[CH3:19])[C:9]=2[C:10]=1[CH3:11])=[O:5])[CH3:2]To 5-chloro-4-hydroxy-3-methyl-benzofuran-2-carboxylic acid ethyl ester (110 mg) was added 2 mL of isopropylbromide, 150 mg of K2CO3 and 4 mL of DMF. The mixture was stirred at room temperature overnight. The mixture was washed with brine and extracted with ethyl acetate. The combined ethyl acetate layers were washed with brine. Removal of the solvent in vacuo gave 134 mg of 5-chloro-4-isopropoxy-3-methyl-benzofuran-2-carboxylic acid ethyl ester as a thick colorless oil (100% yield).
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