To a three-necked flask were charged potassium thiocyanate (5.0 g, 50.4 mmol), and tetrahydrofuran (110 mL). 2-Fluoro-5-(trifluoromethyl)benzoyl chloride (10.39 g, 41.7 mmol) was added into the flask slowly at room temperature. The reaction mixture was stirred at room temperature for 3 hours or until less than 1% of the acid chloride remains. The reaction mixture was filtered to remove potassium chloride by-product, and rinsed with tetrahydrofuran (10 mL). The combined solution of 2-fluoro-5-(trifluoromethyl)benzoyl isothiocyanate was charged back to the three-necked flask, followed by addition of N-butyl-2-chloropyridin-3-amine (6.91 g, 37.4 mmol) and tetrahydrofuran (100 mL). The reaction mixture was heated to approximately 50° C., and stirred vigorously for 2 days. The product suspension was then cooled to room temperature, and the product collected by filtration. The wet cake was washed with tetrahydrofuran (50 mL), and dried under vacuum at 50° C. to give the desired product (7.83 g, 48% isolated yield). MS-ESI: 398 (M+1); 1H-NMR (DMSO-d6) δ 0.96 (3H, t, J=7.4 Hz), 1.42 (2H, m), 1.81 (2H, m), 4.51 (2H, t, J=7.6 Hz), 7.53-7.64 (2H, m), 7.97-8.05 (1H, m), 8.21 (1H, dd, J=8.3, 1.2 Hz), 8.46 (1H, dd, J=6.7, 2.3 Hz), 8.52 (1H, dd, J=4.7, 1.2 Hz).
