[F:1][C:2]1[N:7]=[C:6]([C:8]([OH:10])=O)[CH:5]=[CH:4][CH:3]=1.[CH3:11][NH:12][O:13][CH3:14].CCN(CC)CC.CCCP1(OP(CCC)(=O)OP(CCC)(=O)O1)=O>C(Cl)Cl>[CH3:14][O:13][N:12]([CH3:11])[C:8]([C:6]1[CH:5]=[CH:4][CH:3]=[C:2]([F:1])[N:7]=1)=[O:10]To a cooled mixture of 6-fluoro picolinic acid (1.19 g, 8.43 mmol), N,O-dimethylhydroxylamine (860 mg, 8.82 mmol) and Et3N (3.27 mL, 23.52 mmol) in CH2Cl2 (10 mL) was added 1-propane phosphonic acid cyclic anhydride (4.49 mL, 7.05 mmol; 50 wt % solution in EtOAc) dropwise and stirred at room temperature for 3 h. The reaction mixture was filtered, washed with CH2Cl2 (2×10 mL), evaporated to dryness, and subjected to column chromatography (SiO2, 40% EtOAc-hexanes) to obtain 6-fluoro-pyridine-2-carboxylic acid methoxy-methyl-amide (1.19 g) in 73% yield. ESMS m/z (relative intensity): 185 (M+H)+ (100).
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