[CH3:1][O:2][C:3]1[CH:4]=[CH:5][CH:6]=[C:7]2[C:12]=1[O:11][CH2:10][C:9]([C:13]([OH:15])=O)=[CH:8]2.[CH2:16]([N:18](CC)[CH2:19][CH3:20])[CH3:17].P(C#N)(OCC)(OCC)=[O:24].O>CN(C=O)C>[CH3:1][O:2][C:3]1[CH:4]=[CH:5][CH:6]=[C:7]2[C:12]=1[O:11][CH2:10][C:9]([C:13]([N:18]1[CH2:19][CH2:20][O:24][CH2:17][CH2:16]1)=[O:15])=[CH:8]2To a solution (200 ml) of 8-methoxy-2H-chromene-3-carboxylic acid (10.0 g) in DMF were added triethylamine (8.6 ml) and diethyl cyanophosphate (10.0 ml) and the mixture was stirred at room temperature for 3 hr. The reaction mixture was poured into water and extracted with ethyl acetate. The organic layer was washed with water and dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure and the residue was purified by silica gel column chromatography (chloroform/ethyl acetate) to give the title compound (3.5 g) as a brown oil.
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