[F:1][C:2]1[CH:11]=[C:10]2[C:5]([CH:6]([C:12]([OH:14])=[O:13])[CH2:7][CH2:8][O:9]2)=[CH:4][CH:3]=1.[CH2:15]1COCC1>CO.S(=O)(=O)(O)O.C(OCC)(=O)C.C(=O)(O)[O-].[Na+]>[F:1][C:2]1[CH:11]=[C:10]2[C:5]([CH:6]([C:12]([O:14][CH3:15])=[O:13])[CH2:7][CH2:8][O:9]2)=[CH:4][CH:3]=17-Fluoro-3,4-dihydro-2H-chromene-4-carboxylic acid (346 mg, 1.76 mmol) was diluted with (THF) 2 mL, methanol (2 mL) and 4 drops of sulfuric acid. The reaction was heated at 55° C. and stirred for 12 hours. The reaction was cooled to ambient temperature, diluted with ethyl acetate and saturated sodium bicarbonate. The layers were separated and the organic layer was dried over MgSO4, filtered and concentrated to yield the title compound (366 mg, 98.7% yield).
불러오는 중…