Step 1. Synthesis of tert-butyl 4-(4-bromobenzoyl)-piperidine-1-carboxylate. To a 250 mL round bottom flask was added 4-(4-bromobenzoyl)piperidine (5 g, 20 mmol), tetrahydrofuran (30 mL), water (30 mL), sodium carbonate (10 g, 90 mmol) and di-tert-butyl dicarbonate (4.35 g, 20.0 mmol). The reaction mixture was stirred at room temperature for 2 h and then partitioned with ethyl acetate and water. The aqueous layer was extracted twice with ethyl acetate, the organic phases were combined, washed with brine, dried, filtered and concentrated to give 7.1 g (100% yield) of tert-butyl 4-(4-bromobenzoyl)-piperidine-1-carboxylate.
