[F:1][C:2]1[CH:3]=[C:4]([CH2:11][C:12]([O:14][CH2:15][CH3:16])=[O:13])[C:5]2[O:9][CH:8]=[CH:7][C:6]=2[CH:10]=1.[CH:17]([N-]C(C)C)(C)C.[Li+].IC>O1CCCC1.C(OCC)(=O)C>[F:1][C:2]1[CH:3]=[C:4]([CH:11]([CH3:17])[C:12]([O:14][CH2:15][CH3:16])=[O:13])[C:5]2[O:9][CH:8]=[CH:7][C:6]=2[CH:10]=1A solution of 1.09 gm (4.90 mMol) ethyl 2-(5-fluorobenzofur-7-yl)acetate in 5 mL tetrahydrofuran was cooled to −78° C. To this solution were slowly added 6.1 mL (6.13 mMol) lithium diisopropylamide (1.0 M in tetrahydrofuran) and the mixture was stirred at −78° C. for 1 hour. To this solution were then added 0.76 mL (12.25 mMol) iodomethane and the mixture was allowed to warm to room temperature over 1 hour. The reaction mixture was then diluted with ethyl acetate and the resulting solution washed sequentially with water, saturated aqueous sodium bicarbonate, and saturated aqueous sodium chloride. The remaining organic phase was concentrated under reduced pressure and the residue subjected to flash silica gel chromatography, eluting with hexane containing 20% ethyl acetate. Fractions containing product were combined and concentrated under reduced pressure to provide 0.723 gm (62%) of the desired compound.
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