1,3-Dibromobenzene → tert-Butyl 4-(3-bromophenyl)piperazine-1-carboxylate

Participants

Reaction Steps

Into a 250-mL round-bottom flask purged and maintained with an inert atmosphere of nitrogen, was placed copper(I) iodide (1.0 g, 5.26 mmol, 0.20 equiv), L-proline (930 mg, 8.09 mmol, 0.30 equiv) in DMSO (50 mL). The resulting solution was stirred for 15 min at room temperature. Then, tert-butyl piperazine-1-carboxylate (5 g, 26.88 mmol, 1.00 equiv), 1,3-dibromobenzene (9.5 g, 40.25 mmol, 1.50 equiv), potassium carbonate (7.4 g, 53.62 mmol, 1.99 equiv) was added. The resulting solution was stirred overnight at 90° C. The reaction was then quenched by the addition of 100 mL of water. The resulting solution was extracted with 2×100 mL of ethyl acetate and the organic layers combined and dried over anhydrous sodium sulfate and concentrated under vacuum. The residue was applied onto a silica gel column with ethyl acetate/petroleum ether (1:6). This resulted in 2.9 g of tert-butyl 4-(3-bromophenyl)piperazine-1-carboxylate as a white solid.

Provenance & Evidence