To a solution of 4-bromo-5-chloro-2-nitroaniline (550 mg, 2.19 mmol) from the previous step and TFA (2.26 mL) in DCM (10 mL) at −15° C. was added NaBH(OAc)3 (1.39 g, 5.37 mmol). Then a solution of 2-(methylthio)benzo[d]oxazole-6-carbaldehyde (465 mg, 2.41 mmol) in DCM (6 mL) was added to the mixture. After complete addition, the mixture was stirred at −10° C. to 0° C. for 2 h. The reaction mixture was diluted with DCM and washed sequentially 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 5:1 to 2:1 petroleum ether/DCM to give 4-bromo-5-chloro-N-((2-(methylthio)benzo[d]oxazol-6-yl)methyl)-2-nitroaniline as a yellow solid (451 mg, 48.2%). 1H NMR (300 MHz, DMSO-d6) δ 8.81 (t, 1H), 8.34 (s, 1H), 7.66 (s, 1H), 7.60 (d, J=8.1 Hz, 1H), 7.37 (d, J=6.9 Hz, 1H), 7.19 (s, 1H), 4.76 (d, J=6.3 Hz, 2H), 2.74 (s, 3H). LCMS (ESI) m/z 428 (M+H)+.
