60% Sodium hydride in mineral oil (60 mg, 1.50 mmol) was added in one portion to (S)-3-cyclobutoxy-2-hydroxy-N-(5-methylpyrazin-2-yl)propanamide (Intermediate R1) (251 mg, 1.00 mmol) in anhydrous THF (5 mL) at 0° C. under nitrogen. The resulting suspension was stirred at 0° C. for 10 minutes and then 4-chloro-1-(5-chloro-3-(trifluoromethyl)pyridin-2-yl)-1H-pyrazolo[3,4-d]pyrimidine (Intermediate K3) (334 mg, 1.00 mmol) as suspension in dry THF (2.5 mL) added dropwise over 1 minute. The mixture was stirred at 0° C. for 15 mins, allowed to warm to ambient temperature and stirred for 6 hours. 1M Citric acid (10 mL) was added and the mixture extracted with ethyl acetate (2×25 mL). The combined organic extracts were washed with water (25 mL) and brine (25 mL), dried (MgSO4) and evaporated. The residue was purified by flash silica chromatography, eluting with 50 to 100% ethyl acetate in isohexane to give the product (550 mg, 100%). 1H NMR (400 MHz, CDCl3) δ 1.46-1.54 (1H, m), 1.66-1.74 (1H, m), 1.89-2.01 (2H, m), 2.18-2.25 (2H, m), 2.54 (3H, s), 3.98-4.08 (3H, m), 6.04 (1H, t), 8.12 (1H, d), 8.25 (1H, d), 8.43 (1H, s), 8.62 (1H, s), 8.63-8.65 (1H, m), 8.82 (1H, d), 9.44 (1H, d); m/z (ESI+) (M+H)+=549; HPLC tR=2.56 min.
