[F:1][C:2]1[CH:3]=[CH:4][C:5]([C:15]([NH2:17])=[O:16])=[C:6]2[C:11]=1[O:10][CH2:9][C:8]([N+:12]([O-:14])=[O:13])=[CH:7]2.[BH4-].[Na+]>C(Cl)(Cl)Cl.C(O)(C)C>[F:1][C:2]1[CH:3]=[CH:4][C:5]([C:15]([NH2:17])=[O:16])=[C:6]2[C:11]=1[O:10][CH2:9][CH:8]([N+:12]([O-:14])=[O:13])[CH2:7]28-Fluoro-3-nitro-2H-1-benzopyran-5-carboxamide (730 mg, 3.1 mmol) was slurried in chloroform (75 mL) and isopropyl alcohol (25 mL). To the stirred mixture, silica gel (2.2 g, 230-400 mesh ASTM) was added followed by powdered sodium borohydride (255 mg, 6.2 mmol) portionwise over a period of 15 min. After the addition was complete, the reaction was stirred for 20 min. and the reaction was then quenched by the addition of acetic acid (2 mL) and stirred for an additional 30 min. The insoluble material was filtered off and the solvent removed in vacuo. The residue was partitioned between ethyl acetate and water. The aqueous phase was extracted with ethyl acetate, the combined ethyl acetate phases were treated with brine, dried with MgSO4, filtered, and the solvent was removed in vacuo to give 0.67 g (91% yield) of an off-white solid as the title compound (mp 191.0-191.5° C.). EIMS (70 eV) m/z (relative intensity) 240 (1, M+), 195 (17), 194 (100), 193 (17), 177 (26), 151 (44), 149 (27), 148 (18), 123 (23), 103 (48), 102 (11), 101 (29), 96 (13), 95 (15), 94 (11), 88 (41), 83 (14), 77 (25), 76 (11), 75 (39), 74(23), 70 (10), 63 (11), 60 (11), 51 (17), 50 (10).
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