[BH4-].[Na+].[F:3][C:4]1[C:9]([F:10])=[CH:8][CH:7]=[C:6]([N+:11]([O-:13])=[O:12])[C:5]=1[CH2:14][C:15](O)=[O:16].C(Cl)Cl.C([O-])(O)=O.[Na+]>C1COCC1.O>[F:3][C:4]1[C:9]([F:10])=[CH:8][CH:7]=[C:6]([N+:11]([O-:13])=[O:12])[C:5]=1[CH2:14][CH2:15][OH:16]
To a mixture of NaBH4 (3.60 g, 95.4 mmol) in THF (12 mL) cooled below 10° C. was added a solution of 2-(2,3-difluoro-6-nitrophenyl)acetic acid (10.9 g, 50.2 mmol), as prepared in the preceding step, in THF (4 mL) over a period of 1 hour. To this mixture was added a solution of boron trifluoride diethyl etherate complex (16.5 mL, 131 mmol) in THF (24 mL) over a period of 1 hour, keeping the reaction temperature below 10° C. After the addition the reaction was continued to stir on ice for 15 minutes, and then at ambient temperature for 20 minutes. To a mixture of DCM (180 mL) and H2O (140 mL) was added NaHCO3 (15 g, 179 mmol). The reaction mixture was slowly added to the above NaHCO3 solution and stirred overnight. The organic layer was separated, dried over Na2SO4, and concentrated to give the title compound (10.1 g, 99% yield) as light brown oil. 1H NMR (400 MHz, CDCl3) δ 7.82 (dd, J=9.1, 4.4 Hz, 1H), 7.27-7.18 (m, 1H), 3.95 (t, J=6.3 Hz, 2H), 3.30-3.27 (m, 2H), 1.82 (s, 1H).
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