[F:1][C:2]1[CH:7]=[C:6]([N+:8]([O-:10])=[O:9])[CH:5]=[C:4]([F:11])[C:3]=1[N:12]1[CH2:21][CH2:20][C:15]2(OCC[O:16]2)[CH2:14][CH2:13]1.O.Cl>CC(C)=O>[F:1][C:2]1[CH:7]=[C:6]([N+:8]([O-:10])=[O:9])[CH:5]=[C:4]([F:11])[C:3]=1[N:12]1[CH2:21][CH2:20][C:15](=[O:16])[CH2:14][CH2:13]1The crude 8-(2,6-difluoro-4-nitrophenyl)-1,4-dioxa-8-azaspiro[4.5]decane from the preceding procedure was dissolved in 4:1 acetone:water (100 mL). Concentrated HCl (5 mL) was added, and the resulting mixture was stirred at 50° C. for 8 hours and then cooled to room temperature. The mixture was concentrated in vacuo to approximately 20 mL, which was carefully added to concentrated aq. NaHCO3 (100 mL) and extracted with EtOAc (2×100 mL). The combined organic extracts were dried over Na2SO4, filtered and concentrated in vacuo. The crude product was triturated with Et2O and hexanes to give a bright-yellow solid that was collected and dried to provide the title compound (7.13 g, 81%).
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