[CH3:1][O:2][C:3]1[CH:8]=[CH:7][C:6]([NH2:9])=[CH:5][CH:4]=1.C(N(CC)CC)C.[C:17](O)(=[O:24])[C:18]1[CH:23]=[CH:22][N:21]=[CH:20][CH:19]=1.CCCP1(OP(CCC)(=O)OP(CCC)(=O)O1)=O>C(OCC)(=O)C>[CH3:1][O:2][C:3]1[CH:8]=[CH:7][C:6]([NH:9][C:17](=[O:24])[C:18]2[CH:23]=[CH:22][N:21]=[CH:20][CH:19]=2)=[CH:5][CH:4]=1A solution of p-anisidine (2.46 g, 20 mmol) and triethylamine (13.9 mL, 100 mmol) in ethyl acetate (200 mL) was treated with isonicotinic acid (2.46 g, 20 mmol) followed by 1-propanephosphonic acid cyclic anhydride (50% in ethyl acetate, 15.1 mL, 24 mmol). After stirring at 23° C. for 4 h, the reaction mixture was diluted with ethyl acetate, was washed with water and with brine, and the organic layer was dried (MgSO4), was filtered, and was concentrated in vacuo. Purification by silica gel chromatography with chloroform-methanol (40:1) gave 4 g (88% yield) of the title compound; diagnostic 13C NMR signals (100 MHz, CD3OD/CDCl3) δ 164.825, 157.213, 149.758, 143.349, 130.989, 123.085, 122.068, 55.285; MS (AP/Cl) 229.3 (M+H)+.
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