71916-73-9

91830-17-0

General procedure for the synthesis of 5-bromo-3H-spiro[benzofuran-2(3H),4'-piperidine] from spiro[benzofuran-2(3H),4'-piperidine]: 1. Synthesis of intermediates 1-5: N-bromosuccinimide (13.9 g, 78.7 mmol) was added to a methanol solution of 1-4 (7.44 g, 39.4 mmol) at 0 °C, and the reaction mixture was stirred at 0 °C for 6 hours. After completion of the reaction, the reaction mixture was concentrated under reduced pressure and the residue was diluted with water and ethyl acetate. The organic layer was separated and the aqueous phase was alkalized with saturated sodium bicarbonate solution to pH 8. The aqueous layer was extracted with ethyl acetate and the combined organic phases were dried with anhydrous sodium sulfate, filtered to remove the solids, and the filtrate was concentrated to give 1-5 as a brown solid (6 g, 62%). 1H NMR (400MHz, CD3OD) δ: 7.39 (s, 1H), 7.29 (d, J = 8.4Hz, 1H), 6.75 (d, J = 8.4Hz, 1H), 3.43-3.40 (m, 4H), 3.19 (s, 2H), 2.22-2.19 (m, 2H), 2.12-2.04 (m, 2H). MS (ESI): m/z 268.2, 270 (M + H)+.