Hydrochloric Acid → (4-(3,5-Bis(trifluoromethyl)phenyl)piperidin-1-yl)(6-methoxy-[1,2,4]triazolo[4,3-a]pyridin-3-yl) methanone

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Reaction Steps

To a solution of ethyl 6-methoxy-[1,2,4]triazolo[4,3-a]pyridine-3-carboxylate (66 mg, 0.30 mmol) in THF (2.5 mL) was added a solution of LiOH monohydrate (25 mg, 0.60 mmol) in H2O (1.6 mL). The mixture stirred for 20 min and was neutralized with 2 N HCl. The mixture was concentrated under reduced pressure. The obtained residue was diluted in DMF (3.3 mL) under an atmosphere of N2. To this mixture was added 4-(3,5-bis(trifluoromethyl)phenyl)piperidine hydrochloride (20, 100 mg, 0.30 mmol), benzotriazole-1-yl-oxy-tris-(dimethylamino)-phosphonium hexafluorophosphate (266 mg, 0.60 mmol), and diisopropylethylamine (0.16 mL, 0.90 mmol). The mixture was stirred at ambient temperature for 18 h. The resulting mixture was diluted with H2O (20 mL) and extracted with EtOAc (4×30 mL). The combined organic extracts were washed with a saturated brine solution (3×30 ml) and concentrated under reduced pressure. The obtained residue was chromatographed over silica gel (Isco CombiFlash Rf unit, 24 g Redisep column, 0% to 2% MeOH in CH2Cl2 with 0.1% NH4OH in CH2Cl2). The obtained residue was dissolved in CH2Cl2 (10 mL) and hexanes (100 mL). The solution was partially concentrated and the resulting solids were collected by filtration to provide (4-(3,5-bis(trifluoromethyl)phenyl)piperidin-1-yl)(6-methoxy-[1,2,4]triazolo[4,3-a]pyridin-3-yl) methanone as an off-white solid (80 mg, 56%): mp 146-149° C.; 1H NMR (500 MHz, DMSO-d6) δ 8.55 (d, J=2.0 Hz, 1H), 8.03 (s, 2H), 7.95-7.89 (m, 2H), 7.38 (dd, J=10, 2.5 Hz, 1H), 5.40-5.33 (m, 1H), 4.81-4.73 (m, 1H), 3.85 (s, 3H), 3.39-3.31 (m, 1H, overlaps with H2O), 3.26-3.16 (m, 1H), 3.02-2.93 (m, 1H), 2.03-1.77 (m, 4H); ESI MS m/z 473 [M+H]+.

Provenance & Evidence