C[O:2][C:3](=O)[C:4]1[CH:9]=[C:8]([F:10])[C:7]([N+:11]([O-:13])=[O:12])=[C:6]([F:14])[CH:5]=1.CC(C[AlH]CC(C)C)C.CCCCCC.C(C(C(C([O-])=O)O)O)([O-])=O.[K+].[K+]>C1COCC1>[F:10][C:8]1[CH:9]=[C:4]([CH2:3][OH:2])[CH:5]=[C:6]([F:14])[C:7]=1[N+:11]([O-:13])=[O:12]To a solution of 3,5-difluoro-4-nitro-benzoic acid methyl ester (10.95 g, 50 mmol) in THF (250 mL) was added at 0-5° C. under argon a 1M DIBAL solution in hexane (165 mL, 165 mmol) within 1.5 h. The reaction mixture was stirred for 2.5 h at 0-5° C. before it was added to 200 mL cold 1M aq. potassium tartrate solution under ice-cooling. After stirring the reaction mixture for 0.5 h at 25° C. the aqueous phase was extracted with EtOAc. Combined organic extracts were washed with brine, dried over MgSO4, filtered and evaporated to provide the title compound as a yellow solid: TLC (hexane-EtOAc 1.1) Rf=0.35; HPLC RtA=1.31 min; 1H NMR (400 MHz, CDCl3): δ 7.12 (d, 2H), 4.77 (s, 2H).
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