Hydrochloric Acid → 4-(1-Methyl-4-phenyl-1H-imidazol-2-yl)-piperidin-4-ol dihydrochloride

Participants

Reaction Conditions

Reaction Steps

Dissolve 1-methyl-4-phenyl-1H-imidazole (9.05 mmoles; 1.43 g) in anhydrous tetrahydrofuran (30.00 mL) and the mixture cooled to −78° C. Slowly add n-butyl lithium (1.30 equiv; 11.77 mmoles; 7.35 mL) (1.6M in hexanes) and the reaction stirs at −78° C. for 30 minutes then add a THF (20 mL) solution of N-T-butoxycarbonyl-4-piperidone (11.77 mmoles; 2.34 g) dropwise over 20 min. Allow to stir overnight with warming to room temperature. Dilute with DCM and saturated aq. sodium chloride/water (50/50), (2×DCM), then dry over MgSO4. Filter and concentrate to 3.8 g crude yellow oil. Purify the reaction by using ISCO chromatography over a Biotage 40M column eluting with 50:50 EtOAc:Hex at a flow rate of 40 mL/min. Concentrate product fractions to 2.00 g of 4-hydroxy-4-(1-methyl-4-phenyl-1H-imidazol-2-yl)-piperidine-1-carboxylic acid tert-butyl ester as a white solid. ES-MS (M+H)=358.3. Dissolve it in 5 mL dichloromethane and add hydrogen chloride (20.00 mmoles; 5.00 mL)(4M in dioxane) slowly at room temperature. After approximately 5 min the solution becomes cloudy and add 3 mL of methanol to get the reaction back into solution. After 1 h the reaction is 95% complete. Add 1 mL of 4M HCl in dioxane and stir 15 min. Concentrate to 2.1 g of 4-(1-Methyl-4-phenyl-1H-imidazol-2-yl)-piperidin-4-ol dihydrochloride as a light yellow solid. MS(ES): (m/z)=258.3 [M+H].

Provenance & Evidence