Reaction Steps
3-Hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(piperidin-1-yl)ethyl]pyridin-4(1H)-one (Apo7054) was prepared from the reaction of 5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,2-dimethylpyridin-4(1H)-one hydrochloride (304 mg, 1.0 mmol) and piperidine (2.0 mL, 20.3 mmol). The reaction was completed within 20 min, and Apo7054 was obtained as a solid product (232 mg). Yield=73%; HPLC Method 1, purity (AUC)=99.4% at 280 nm; 1H NMR (DMSO-D6) δ (ppm): 7.66 (s, 1H), 4.83-4.94 (m, 1H), 3.71 (s, 3H), 2.56 (m, 2H), 2.41 (m, 2H), 2.27 (s, 3H), 1.46 (br, 4H), 1.28 (br, 2H); MS-ESI m/z 305 [M+1]+ (100%), 220. (ii) 3-Hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(1H-imidazol-1-yl)ethyl]pyridin-4(1H)-one (Apo7055) was prepared from 5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,2-dimethylpyridin-4(1H)-one hydrochloride (505 mg, 1.7 mmol) and imidazole (3.5 g, 51.4 mmol). The reaction was stopped when analysis of the HPLC chromatogram (Method 1) of the reaction mixture indicated higher than 98% conversion. The reaction mixture was concentrated to give a solid. The solid was dissolved in de-ionized water (4 mL), and the pH of the solution was adjusted to 6.5 with a 6.00 N hydrochloric acid solution. The resulting solution was repeatedly extracted with dichloromethane (15 mL×4, 30 mL×2). The organic fractions were combined, dried over sodium sulfate, filtered, and concentrated. The desired compound Apo7055 was obtained as a solid from dichloromethane (320 mg). Yield=64%; HPLC purity (AUC): 99.7% at 280 nm); 1H NMR (DMSO-D6) δ (ppm): 8.15 (s, 1H), 7.98 (s, 1H), 7.52 (s, 1H), 6.96 (s, 1H), 6.66 (q, J=9.1 Hz, 1H), 3.76 (s, 3H), 2.29 (s, 3H). MS-ESI m/z 288 [M+1]+, 220 (100%). (iii) 3-Hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(methylamino)ethyl]pyridin-4(1H)-one (Apo7056) was prepared from 5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,2-dimethylpyridin-4(1H)-one hydrochloride (400 mg, 1.4 mmol) and methylamine (3.0 mL, 34.4 mmol). The reaction was essentially completed within 15 min. The reaction mixture was concentrated to give a solid. A sample of salt free Apo7056 product was obtained by purification using the Biotage instrument (C18 reversed phase; eluant: water and acetonitrile; gradient, 100:0 to 100:4). (48 mg).
