[CH2:1]([O:3][C:4]([C:6]1[O:7][C:8]2[CH:14]=[C:13]([OH:15])[CH:12]=[CH:11][C:9]=2[CH:10]=1)=[O:5])[CH3:2].[H-].[Na+].Br[CH2:19][C:20]#[C:21][CH3:22].O>O1CCCC1.CN(C)C=O>[CH2:1]([O:3][C:4]([C:6]1[O:7][C:8]2[CH:14]=[C:13]([O:15][CH2:19][C:20]#[C:21][CH3:22])[CH:12]=[CH:11][C:9]=2[CH:10]=1)=[O:5])[CH3:2]To a mixed solution of 6-hydroxy-benzofuran-2-carboxylic acid ethyl ester (250 mg, 1.21 mmol) in tetrahydrofuran (5 mL) and N,N-dimethylformamide (5 mL) were added sodium hydride (58 mg, 2.42 mmol) and 1-bromo-2-butyne (127 μL) at room temperature, which was stirred at room temperature for 1 hour. Water was added to the reaction solution followed by extraction with ethyl acetate. The organic layer was washed with water and sat. NaCl followed by drying over anhydrous magnesium sulfate and filtering. The filtrate was concentrated under a reduced pressure and the residue was purified by silica gel column chromatography (heptane:ethyl acetate=5:1) to obtain the title compound (254 mg, 81%) as a white solid.
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