N-bromobutanimide → tert-Butyl 3-(7-bromo-2H-benzo[b][1,4]thiazin-4(3H)-yl)pyrrolidine-1-carboxylate

Participants

Reaction Steps

A solution of tert-butyl 3-(2H-benzo[b][1,4]thiazin-4(3H)-yl)pyrrolidine-1-carboxylate (0.41 g, 1.302 mmol) in DMF (5 mL), was cooled to 0° C. and treated dropwise with N-bromosuccinimide (0.17 g, 0.977 mmol) in DMF (5 mL) for 15 minutes. The reaction was kept at 0° C. and was stirred for 1 hour at this temperature. At this time, N-bromosuccinimide (0.023 g, 0.130 mmol) in DMF (1 mL) was added dropwise to the reaction, which was then stirred for 1 hour at 0° C. The solution was treated again with N-bromosuccinimide (0.023 g, 0.130 mmol) in DMF (1 mL) and was stirred for 1 hour at 0° C. The solution was diluted in water (100 mL) and extracted with EtOAc (2×100 mL). The aqueous phase was washed once with EtOAc (50 mL). The organic solutions were combined, washed with water (100 mL) and brine (50 mL), and dried (Na2SO4). The crude material was filtered through a silica pad (20% EtOAc/hexanes) and concentrated to give clear oil (0.47 g, 90%). 1H NMR (CDCl3) δ 7.18 (d, J=2.4 Hz, 1H), 7.07 (d, J=8.7 Hz, 1H), 6.62 (d, J=8.7 Hz, 1H), 4.34-4.28 (m, 1H), 3.71-3.23 (m, 6H), 3.03-3.04 (m, 2H), 2.19-1.95 (m, 2H), 1.47 (s, 9H); ESI-MS (m/z, %): 423, 421 (M+Na, 8), 401, 399 (MH+, 2), 343, 345 (100).

Provenance & Evidence