[Cl:1][C:2]1[O:25][C:5]2=[C:6]([N:10](C(OC(C)(C)C)=O)C(OC(C)(C)C)=O)[N:7]=[CH:8][CH:9]=[C:4]2[CH:3]=1.Cl.O1CCOCC1>C(Cl)Cl>[Cl:1][C:2]1[O:25][C:5]2=[C:6]([NH2:10])[N:7]=[CH:8][CH:9]=[C:4]2[CH:3]=1Di-tert-butyl (2-chlorofuro[2,3-c]pyridin-7-yl)imidodicarbonate (18.0 g, 49.1 mmol) in DCM (100 mL) was cooled in an ice bath and treated with 4 N HCl in 1,4-dioxane (75 mL, 300 mmol) added slowly over several minutes. The reaction was removed from the cooling bath and heated at 55° C. for 16 h. The mixture was concentrated in vacuo. The residue was suspended in DCM and treated with saturated NaHCO3 until the pH reached ˜8.5. The organic layer was washed with water and brine and then dried over anhydrous Na2SO4. The material was purified by flash chromatography (50% EtOAc:DCM) to provide 8.2 g (100%) of the title compound as a white solid. 1H NMR (CDCl3, 400 MHz): δ 4.75 (br s, 2H), 6.54 (s, 1H), 6.85 (d, J=5.3 Hz, 1H), 7.86 (d, J=5.3 Hz, 1H); MS (ESI): 169.12 [M+H]+.
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