Nitric Acid → 3-Nitro-4-trifluoromethyl-6-(2-trifluoromethyl-phenyl)-pyridin-2-ylamine

Sulfuric acid (10 mL) was placed in a 100 mL two-necked round-bottomed flask fitted with a magnetic stir bar and an internal thermometer and cooled to 0° C. 4-Trifluoromethyl-6-(2-trifluoromethyl-phenyl)-pyridin-2-ylamine (720 mg, 2.35 mmol, prepared as described in STEP C above) was added portion wise so that the internal temperature did not exceed 5° C. The resulting mixture was stirred at 0° C. for 1 h. Nitric acid (106 μL, 2.35 mmol) was added slowly, keeping the internal temperature below 10° C. The mixture was stirred an additional 2 h at 0° C., poured over ice water (100 mL), treated with 6 M aqueous NaOH to pH 10, and extracted twice with EtOAc (100 mL). The combined organic extracts were dried over MgSO4 and concentrated in vacuo. The residue was purified on a 24-g SEPRA Si 50 SPE column (Flow rate=20 mL/min; Eluent=EtOAc-hexanes, 1:99 for 10 min, then 1:99 to 1:3 over 40 min) to yield 3-nitro-4-trifluoromethyl-6-(2-trifluoromethyl-phenyl)-pyridin-2-ylamine as a bright yellow solid. Mass Spectrum (LCMS, APCI pos.): Calculated for C13H7N3O2F6: 352.0 (M+H); Measured: 352.0.