Potassium Carbonate → (R)-[3-oxo-1-(2,4,5-trifluoro-benzyl)-3-(1-bromo-3-trifluoromethyl-5,6-dihydro-8H-imidazo[1,5-a]pyrazin-7-yl)-propyl]-carbamic acid tert-butyl ester

Participants

Reaction Steps

tert-Butyl(R)-[3-oxo-1-(2,4,5-trifluoro-benzyl)-3-(3-trifluoromethyl-5,6-dihydro-8H-imidazo[1,5-a]pyrazin-7-yl)-propyl]-carbamate 1m (20.0 g, 39.6 mmol) was dissolved in 300 mL of anhydrous ethanol, and N-bromosuccinimide (14.1 g, 79.2 mmol) was then added to the solution. After stirring for an hour, potassium carbonate (10.9 g, 79.2 mmol) and di-tert-butyl dicarbonate (8.6 g, 39.6 mmol) were added to the mixture, and the mixture was stirred for another one hour. The reaction mixture was filtered through a pad of coarse silica gel, and then the filtrate was concentrated under reduced pressure. The resulting residues were purified by silica gel column chromatography with system B as eluant to obtain the title compound tert-butyl (R)-[3-oxo-1-(2,4,5-trifluoro-benzyl)-3-(1-bromo-3-trifluoromethyl-5,6-dihydro-8H-imidazo[1,5-a]pyrazin-7-yl)-propyl]-carbamate 1n (20.0 g, yield 86%) as a white solid. 1HNMR (400 MHz, CDCl3, ppm): δ 7.063 (m, 1H), 6.88 (m, 1H), 4.72 (s, 1H), 4.56 (s, 1H), 4.13 (m, 3H), 3.88 (m, 2H), 2.94 (m, 2H), 2.62 (m, 2H), 1.36 (s, 9H).

Provenance & Evidence