[Cl:1][C:2]1[CH:3]=[CH:4][C:5]([N+:9]([O-:11])=[O:10])=[C:6]([CH:8]=1)[NH2:7].CO[C:14](OC)([CH3:16])[CH3:15].FC(F)(F)C(O)=O>C1(C)C=CC=CC=1.N1C=CC=CC=1.CCOC(C)=O.CCCCCC>[Cl:1][C:2]1[CH:3]=[CH:4][C:5]([N+:9]([O-:11])=[O:10])=[C:6]([CH:8]=1)[NH:7][CH:14]([CH3:16])[CH3:15]
5-chloro-2-nitroaniline (8.6 g; 0.05 mole), 2,2-dimethoxypropane (10.0 ml; 0.09 mole) and trifluoroacetic acid [TFA] (4.0 ml; 0.005 moles) were dissolved in toluene (100 ml) and stirred for 1 hr. A boron/pyridine complex (hereinafter BH3 * pyridine) (5.0 ml; 0.05 moles) was added in 1.0 ml increments. The reaction was exothermic, and the reaction progress was monitored by tlc (40% EtOAc/hexane). Additional TFA, BH3 * pyridine and 2,2-dimethoxypropane were added until the tlc indicated that the 5-chloro-2-nitroaniline was consumed. The reaction mixture was placed on a bed of silica and eluted with toluene. The product was the first major component to elute, which produced 6.6 g (61%) of a yellow crystalline solid.
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