Step 23a: 3-bromo-5-fluoro-2-methylaniline (Compound 0104-69) was added to a solution of trifluoroacetic acid (40 mL) containing 4-fluoro-2-nitrotoluene (10.0 g, 64.4 mmol). Subsequently, sulfuric acid (12.5 mL) was added slowly and N-bromosuccinimide (NBS, 17.2 g, 96.6 mmol) was added in batches. The reaction mixture was stirred at room temperature for 16 hours. After completion of the reaction, the mixture was slowly poured into ice water and stirring was continued for 15 min. Extraction was carried out with ethyl acetate, the organic layers were combined, washed with saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure to give the target product 1-bromo-5-fluoro-2-methyl-3-nitrobenzene (15.0 g, 100% yield) as a yellow oil. The product was characterized by 1H NMR (400 MHz, DMSO-d6): δ 2.41 (s, 3H), 7.96 (dd, J = 8.0,2.4Hz, 1H), 8.02 (dd, J = 8.0,2.4Hz, 1H).
