N-bromobutanimide → 10-Bromo-3,4,6,7,8,9-hexahydropyrazino[1,2-a]indol-1(2H)-one

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Reaction Steps

Into a 250-mL 3-necked round-bottom flask was placed a solution of 1H,2H,3H,4H,6H,7H,8H,9H-pyrazino[1,2-a]indol-1-one 104j (9.5 g, 49.94 mmol, 1.00 equiv) in N,N-dimethylformamide (100 mL), followed by the addition of N-bromosuccinimide (9.8 g, 55.06 mmol, 1.10 equiv) in several batches at 0° C. The resulting solution was stirred at room temperature for 2 h and diluted with 500 mL of water. The precipitate was filtered and dried in a vacuum oven to afford 9.5 g (71%) of 119a as a light brown solid.

Provenance & Evidence