Sodium hydride (44.4 mg, 1.11 mmol) was added to (S)-3-cyclobutoxy-2-hydroxy-N-(5-methylpyrazin-2-yl)propanamide (Intermediate R1) (186 mg, 0.74 mmol) in anhydrous THF (5 mL) at 0° C. under nitrogen. The resulting mixture was stirred for 10 minutes at 0° C. and 4-chloro-1-(2-chlorophenyl)-1H-pyrazolo[3,4-d]pyrimidine (Intermediate B1) (255 mg, 0.96 mmol) was added and the reaction was allowed to warm up to room temperature and stirred for 30 minutes. The reaction mixture was diluted with ethyl acetate (20 mL), and washed sequentially with water (10 mL) and saturated brine (5 mL). The organic layer was dried (MgSO4) and evaporated. The crude product was purified by flash silica chromatography, eluting with 0-100% ethyl acetate in isohexane to afford the product (262 mg, 73.8%). 1H NMR (400 MHz, DMSO) δ 1.39-1.52 (m, 1H), 1.56-1.67 (m, 1H), 1.77-1.91 (m, 2H), 2.13-2.24 (m, 2H), 2.44 (s, 3H), 3.88-4.02 (m, 2H), 4.06-4.15 (m, 1H), 5.89-5.94 (m, 1H), 7.56-7.70 (m, 3H), 7.73-7.78 (m, 1H), 8.31-8.33 (m, 1H), 8.54 (s, 1H), 8.63 (s, 1H), 9.10 (s, 1H), 11.17 (s, 1H). m/z (ESI+) (M+H)+=480.33; HPLC tR=2.45 min.
