[F:1][C:2]1[C:11]([OH:12])=[CH:10][C:5]([C:6]([O:8][CH3:9])=[O:7])=[C:4]([N+:13]([O-])=O)[CH:3]=1.CO.[H][H]>[Pd].C1COCC1>[NH2:13][C:4]1[CH:3]=[C:2]([F:1])[C:11]([OH:12])=[CH:10][C:5]=1[C:6]([O:8][CH3:9])=[O:7]
Palladium on carbon (2.5 wt. %, wet, 8.5 g, 0.005 eq) was charged into a 1 L Parr bomb. Then, methyl 4-fluoro-5-hydroxy-2-nitrobenzoate, 62 g, 0.29 mol, 1 eq) and MeOH (300 mL) were charged. The bomb was sealed, and pressurized/vented three times with hydrogen, and pressured with 100 psi hydrogen. The reaction mixture was stirred, until the hydrogen pressure was not dropping. The bomb was opened, and an HPLC sample showed that the reaction was complete. The mixture was diluted with 400 ml of THF and filtered through a Celite pad. The solution was concentrated under vacuum and solvent was switched to MeOH. To the thick suspension in MeOH, water (150 mL) was added in about 30 min. The slurry was filtered. The desired product, methyl 2-amino-4-fluoro-5-hydroxybenzoate, was obtained as off-white solid after drying under vacuum (45.5 g, 85% yield). NMR (DMSO-d6, 400 MHz) δ 9.05 (s, 1H), 7.28 (d, J=10.0 Hz, 1H), 6.54 (d, J=13.4 Hz, 1H), 6.30 (s, 2H), 3.74 (s, 3H). 13C NMR (DMSO-d6, 100 MHz) δ 167.0, 157.0, 154.5, 146.2, 146.1, 134.5, 134.4, 118.2, 104.7, 103.3, 51.4.
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