Trifluoroacetic acid → 5-Bromo-1-methyl-3-(1,2,3,4-tetrahydroisoquinolin-6-ylamino)pyrazin-2(1H)-one

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Reaction Steps

A 100-mL single-neck round-bottomed flask equipped with a magnetic stirrer and nitrogen inlet was purged with nitrogen and charged with 120a (1.14 g, 2.62 mmol), methylene chloride (10 mL) and trifluoroacetic acid (10 mL). The solution was stirred for 2 h at room temperature. After this time, the solution was concentrated under reduced pressure. The residue was partitioned between methylene chloride (100 mL) and 1 M aqueous dibasic potassium phosphate (30 mL). The aqueous layer was extracted with a 20% (v/v) solution of methanol in methylene chloride (3×100 mL). The organic extracts were combined, washed with brine (20 mL) and dried over sodium sulfate. The drying agent was removed by filtration, and the filtrate was concentrated under reduced pressure to afford a 68% yield (600 mg) of 153a as an off-white solid: mp 170-171° C.; 1H NMR (300 MHz, DMSO-d6) d 9.30 (s, 1H), 7.62 (m, 2H), 7.31 (s, 1H), 6.97 (d, 1H, J=7.8 Hz), 4.10 (br s, 1H), 3.83 (s, 2H), 3.43 (s, 3H), 2.96 (t, 2H, J=5.7 Hz), 2.68 (t, 2H, J=5.7 Hz); MS (ESI+) m/z 334.0 (M+H).

Provenance & Evidence