[Mn]([O-])(=O)(=O)=[O:2].[K+].[C:7]([C:9]1[CH:27]=[CH:26][C:12]([CH2:13][O:14][C:15]2[CH:16]=[CH:17][C:18]([N+:23]([O-:25])=[O:24])=[C:19]([CH:22]=2)[CH:20]=[O:21])=[CH:11][CH:10]=1)#[N:8]>[Br-].C([N+](CCCC)(CCCC)CCCC)CCC.N1C=CC=CC=1>[C:7]([C:9]1[CH:10]=[CH:11][C:12]([CH2:13][O:14][C:15]2[CH:16]=[CH:17][C:18]([N+:23]([O-:25])=[O:24])=[C:19]([CH:22]=2)[C:20]([OH:2])=[O:21])=[CH:26][CH:27]=1)#[N:8]Potassium permanganate (638 g, 39.1 mmol) was added in portions to a stirred solution of 13.8 g (48.9 mmol) of 5-(4-cyanobenzyloxy)-2-nitrobenzaldehyde and 1.58 g (4.89 mmol) of tetrabutylammonium bromide in 70 mL of pyridine. After 1 h, the solvent was removed in vacuo and the residue was partitioned between ethyl acetate and water. Sodium hydrogen sulfite was added to destroy excess permanganate and the aqueous phase was separated and extracted with ethyl acetate. The combined organics were washed with 1N sodium hydrogen sulfate, brine, dried over anhydrous magnesium sulfate, and concentrated to give 14.6 g of 5-(4-cyanobenzyloxy)-2-nitrobenzoic acid as a powder, used without further purification. 1H NMR (300 MHz, d6 -acetone) d 8.07 (1H, d, J=8.8 Hz, O--Ar--H), 7.86 (2H, d, J=8.3 Hz, NC--Ar--H2), 7.78 (2H, d, J=8.3 Hz, NC--Ar--H2), 7.39 (1H, d, J=2.9 Hz, O--Ar--H), 7.36 (1H, dd, J=8.8, 2.9 Hz, O--Ar--H), 5.48 (2H, s, ArCH2O).
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