1-(1-Benzylpiperidin-4-yl)-2-(2-chlorophenyl)ethanone → 4-(2-Chlorophenylacetyl)piperidine hydrochloride
Reaction equation
C([N:8]1[CH2:13][CH2:12][CH:11]([C:14](=[O:23])[CH2:15][C:16]2[CH:21]=[CH:20][CH:19]=[CH:18][C:17]=2[Cl:22])[CH2:10][CH2:9]1)C1C=CC=CC=1>ClCCCl.ClC(OC(Cl)C)=O>[ClH:22].[Cl:22][C:17]1[CH:18]=[CH:19][CH:20]=[CH:21][C:16]=1[CH2:15][C:14]([CH:11]1[CH2:10][CH2:9][NH:8][CH2:13][CH2:12]1)=[O:23]Participants
4
Procedure
After dissolving 252 mg of 1-(1-benzylpiperidin-4-yl)-2-(2-chlorophenyl)ethanone in 3 ml of 1,2-dichloroethane, 0.1 ml of 1-chloroethyl chloroformate was added while stirring on ice, and the mixture was heated to reflux for 1 hour. The reaction solution was concentrated under reduced pressure, 3 ml of methanol was added to the residue, and heating to reflux was continued for 30 minutes. The reaction solution was concentrated under reduced pressure, ethyl acetate was added to the residue and the precipitate was filtered out to obtain 171 mg of 4-(2-chlorophenylacetyl)piperidine hydrochloride. After then suspending 98 mg of the 4-(2-chlorophenylacetyl)piperidine hydrochloride in 3 ml of dichloromethane, 77 mg of 3-tert-butoxypyrazine-2-carboxaldehyde and 114 mg of sodium triacetoxyborohydride were added while stirring on ice, and the stirring was continued overnight at room temperature. A 1N sodium hydroxide solution was added to the reaction mixture to render it alkaline, and then extraction was performed with ethyl acetate. The organic layer was washed with saturated brine and dried over anhydrous magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was purified by silica gel column chromatography (solvent: n-hexane/ethyl acetate) to obtain the title compound (112 mg, 78% yield).