[Br:1][C:2]1[CH:8]=[CH:7][C:5]([NH2:6])=[C:4]([N+:9]([O-:11])=[O:10])[CH:3]=1.C(O)(C(F)(F)F)=O.[BH-](OC(C)=O)(OC(C)=O)OC(C)=O.[Na+].[CH3:33][S:34][C:35]1[O:36][C:37]2[CH:43]=[C:42]([CH:44]=O)[CH:41]=[CH:40][C:38]=2[N:39]=1>C(Cl)Cl>[Br:1][C:2]1[CH:8]=[CH:7][C:5]([NH:6][CH2:44][C:42]2[CH:41]=[CH:40][C:38]3[N:39]=[C:35]([S:34][CH3:33])[O:36][C:37]=3[CH:43]=2)=[C:4]([N+:9]([O-:11])=[O:10])[CH:3]=1
To a solution of 4-bromo-2-nitroaniline (400 mg, 1.84 mmol) and TFA (1.89 mL) in DCM (8 mL) at −5° C. was added NaBH(OAc)3 (1.17 g, 5.52 mmol). Then to the mixture at 0° C. was added a solution of 2-(methylthio)benzo[d]oxazole-6-carbaldehyde (391 mg, 2.03 mmol) in DCM (7 mL), and the mixture was stirred at 0° C. for 2 h. The mixture was diluted with DCM and washed with H2O, aq NaHCO3 and brine. The organic layer was dried over Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by silica gel chromatography eluting with 20:1 to 10:1 petroleum ether/ethyl acetate to give 4-bromo-N-((2-(methylthio)benzo[d]oxazol-6-yl)methyl)-2-nitroaniline as a yellow solid (704 mg, 97.4%). 1H NMR (300 MHz, DMSO-d6) δ 8.80 (t, 1H), 8.15 (s, 1H), 7.64 (s, 1H), 7.50-7.60 (m, 2H), 7.35 (d, J=8.4 Hz, 1H), 6.90 (d, J=9.3 Hz, 1H), 4.72 (d, J=6.6 Hz, 1H), 2.73 (s, 3H). LCMS (ESI) m/z 394 (M+H)+.
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