Synthesis
To a solution of 3-phenylpiperidin-4-one (3.47 g) and triethylamine (2.76 ml) in acetonitrile (50 ml) prepared in Method 4 was added di-tert-butyl dicarbonate (6.55 g) and the reaction mixture was stirred for 14 hours at room temperature. After completion of the reaction, the mixture was poured into water and the product was extracted with ethyl acetate. The organic phase was washed sequentially with 10% aqueous citric acid and saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent. The crude product obtained was separated and purified by silica gel column chromatography (eluent: hexane/ethyl acetate=10:1) to give tert-butyl 4-oxo-3-phenylpiperidine-1-carboxylate as a white powder (3.90 g, 71% yield). The product can be used directly in the subsequent reaction without further purification.
References
[1] European Journal of Organic Chemistry, 2007, # 26, p. 4376 - 4382
[2] Patent: EP1553084, 2005, A1. Location in patent: Page/Page column 44
