[O:1]1[CH2:6][CH2:5][CH:4]([O:7][C:8]2[N:13]=[CH:12][C:11]([C:14]([O:16]CC)=[O:15])=[CH:10][CH:9]=2)[CH2:3][CH2:2]1.[OH-].[Na+]>CCO>[O:1]1[CH2:2][CH2:3][CH:4]([O:7][C:8]2[N:13]=[CH:12][C:11]([C:14]([OH:16])=[O:15])=[CH:10][CH:9]=2)[CH2:5][CH2:6]1Ethyl 6-(oxan-4-yloxy)pyridine-3-carboxylate (Intermediate 236, 0.239 g, 0.95 mmol) was dissolved in EtOH (5 mL), 2M aq. sodium hydroxide (1.43 mL, 2.85 mmol) was added and the mixture was stirred at room temperature for 4 h. The mixture was concentrated under vacuum and the residue acidified to pH 6 by adding 2M aq. hydrochloric acid. The mixture was then extracted with DCM, followed by chloroform/isopropanol. The organic layer was separated using a hydrophobic frit and concentrated under vacuum to afford the title compound as a white solid (0.162 g, 47%), which was used directly in the next step without further purification. Method C HPLC-MS: MH+ requires m/z=224 Found: m/z=224, Rt=1.06 min (91%).
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