[OH:1][C:2]1[C:9]([CH:10]=O)=[CH:8][C:7]([CH3:12])=[CH:6][C:3]=1[CH:4]=[O:5].C(=O)([O-])[O-].[K+].[K+].Br[CH:20](C(OCC)=O)[C:21]([O:23][CH2:24][CH3:25])=[O:22]>CN(C=O)C>[CH2:24]([O:23][C:21]([C:20]1[O:1][C:2]2[C:3]([CH:4]=[O:5])=[CH:6][C:7]([CH3:12])=[CH:8][C:9]=2[CH:10]=1)=[O:22])[CH3:25]A solution of 2-hydroxy-5-methylisophtalaldehyde (1 g) in DMF (10 ml) was treated under an Argon atmorphere with potassium carbonate (1.01 g) and diethyl bromomalonate (1.60 g). The reaction mixture was heated to 100° C. for 20 hrs, then cooled to r.t., quenched with water and extracted with EtOAc. The organics were dried over MgSO4, filtrated and concentrated to obtain 7-formyl-5-methyl-benzofuran-2-carboxylic acid ethyl ester (1.34 g) as off-white solid. MS (ISP): 233.1 ((M+H)+.). The crude product was used in the next reaction step without further purification.
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