反应详情

4-(1-Fmoc-piperidin-4-yl)-piperazine-1-carboxylic acid tert-butyl ester (0.3 g, 0.61 mmol) was stirred with 20% piperidine in methylene chloride for 40 min. The mixture was concentrated to dryness to give 4-piperidin-4-yl-piperazine-1-carboxylic acid tert-butyl ester. It was then dissolved in tetrahydrofuran (5 mL), and triethylamine (308 mg, 3.05 mmol) and acetic anhydride (86 mg, 0.9 mmol) were added, respectively. After the reaction mixture was stirred for 2 h, water and ethyl acetate were added. The layers were separated, and the aqueous layer was extracted with ethyl acetate. The combined organic extracts were dried over anhydrous sodium sulfate. The solids were filtered off, and the filtrate was concentrated to give 4-(1-acetyl-piperidin-4-yl)-piperazine-1-carboxylic acid tert-butyl ester. It was dissolved in methylene chloride (7 mL), cooled with an ice bath and trifluoroacetic acid was added. The reaction mixture was stirred for 30 min, and the solvent was removed. The residue was triturated with diethyl ether and the solvent was removed to give 1-(4-piperazin-1-yl-piperidin-1-yl)-ethanone trifluoroacetate as a light-yellow foam (151 mg, 76%). LR-MS: 212 [(M+H)+]

1. concentrationThe mixture was concentrated to dryness